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Barton AM, Poulos HM, Koch GW, Kolb TE, Thode AE. Detecting patterns of post-fire pine regeneration in a Madrean Sky Island with field surveys and remote sensing. Sci Total Environ 2023; 867:161517. [PMID: 36638974 DOI: 10.1016/j.scitotenv.2023.161517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 06/17/2023]
Abstract
The American Southwest is experiencing drastic increases in aridity and wildfire incidence, triggering conversion of some frequent surface forests to non-forest. Extensive research has focused on these dynamics in regional ponderosa pine forests, but we know much less about Madrean pine-oak forests, which are broadly distributed from the Sierra Madre in Mexico to the Sky Island mountain ranges in the U.S. Increased fire incidence and drought in these forests are limiting pine regeneration and driving conversion of biodiverse forests to oak shrublands. We investigated regeneration patterns in Pinus engelmannii and P. leiophylla during severe drought 10 years after the Horseshoe Two Megafire in the Chiricahua Mountains, Arizona-a follow-up to an assessment five years post-fire. In long-term plots, we examined changes in pine seedling and resprout recruitment. Past research demonstrated that topography and fire severity influenced pine recruitment across environmental gradients. We investigated here whether Landsat-8 normalized difference vegetation index (NDVI) and evapotranspiration estimated by the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) added explanatory value to our understanding of these patterns. Conversion of Madrean pine-oak forest to oak shrublands continued 6-10 years post-fire. A dense, low oak canopy continued to coalesce in sites subject to severe fire. The importance of resprouts in P. leiophylla regeneration accelerated because these plants outgrew competing oak resprouts. Topography and fire severity (dNBR) were important predictors of 2021 patterns of pine recruitment. NDVI added explanatory value to these models, suggesting its potential in tracking forest dynamics. Evapotranspiration did not add value, likely because ECOSTRESS' larger pixel sizes and moving pixel locations created excessive subpixel heterogeneity in this highly dissected landscape. These models suggest that P. engelmannii is more drought sensitive, was more negatively affected by drought and fire, and is more at risk to shifts in climate and wildfires than P. leiophylla.
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Affiliation(s)
- Andrew M Barton
- Department of Biology, University of Maine at Farmington, Farmington, ME 04938, USA.
| | - Helen M Poulos
- Wesleyan University, College of the Environment and Earth and Environmental Sciences, Middletown, CT 06459, USA.
| | - George W Koch
- Department of Biological Sciences and the Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA.
| | - Thomas E Kolb
- School of Forestry, Northern Arizona University, Flagstaff, AZ 86011, USA.
| | - Andrea E Thode
- School of Forestry, Northern Arizona University, Flagstaff, AZ 86011, USA.
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2
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Koch GW, Schwartz E. Isotopic labeling of metabolic water with 18 O 2. Rapid Commun Mass Spectrom 2023; 37:e9447. [PMID: 36464810 DOI: 10.1002/rcm.9447] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/23/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
RATIONALE Water is the medium of life, is involved in biochemical reactions, and is exchanged among internal pools and with the water in the external environment of organisms. Understanding these processes can be improved by isotopically labeling the metabolic water that is produced inside the cells of organisms during aerobic respiration. METHODS Here we describe a new method for isotopically labeling cellular water by incubating microbes and plant tissues in air enriched in 18 O2 . As oxygen gas is reduced during respiration, H2 18 O is produced. The rate of H2 18 O production and the synthesis of biomolecules that incorporate 18 O from H2 18 O can be quantified using cavity ringdown spectrometry and isotope ratio mass spectrometry. RESULTS For Escherichia coli in solution culture, soil microbial communities, and respiring tissues of plants, the amount of H2 18 O produced was strongly correlated with that of 18 O2 consumed during incubations. Measurements of 18 O in DNA, microbial biomass, and CO2 showed that metabolic water was an important substrate in biosynthesis reactions. CONCLUSIONS Any organism with aerobic respiration is amenable to labeling with 18 O2 , and the method described here enables a new approach to investigate questions regarding plant and microbial physiology. In plants, 18 O introduced as metabolic water could be tracked as it moves between living cells and exchanges with external water. For probing soil microbial physiology, the method described here has the advantage over the application of exogenous H2 18 O of not increasing the soil moisture, a disturbance that can affect microbial metabolism.
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Affiliation(s)
- George W Koch
- Department of Biological Sciences and Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Egbert Schwartz
- Department of Biological Sciences and Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
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3
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Richardson AD, Kong GV, Taylor KM, Le Moine JM, Bowker MA, Barber JJ, Basler D, Carbone MS, Hayer M, Koch GW, Salvatore MR, Sonnemaker AW, Trilling DE. Soil-atmosphere fluxes of CO2, CH4, and N2O across an experimentally-grown, successional gradient of biocrust community types. Front Microbiol 2022; 13:979825. [PMID: 36225383 PMCID: PMC9549369 DOI: 10.3389/fmicb.2022.979825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 09/07/2022] [Indexed: 11/13/2022] Open
Abstract
Biological soil crusts (biocrusts) are critical components of dryland and other ecosystems worldwide, and are increasingly recognized as novel model ecosystems from which more general principles of ecology can be elucidated. Biocrusts are often diverse communities, comprised of both eukaryotic and prokaryotic organisms with a range of metabolic lifestyles that enable the fixation of atmospheric carbon and nitrogen. However, how the function of these biocrust communities varies with succession is incompletely characterized, especially in comparison to more familiar terrestrial ecosystem types such as forests. We conducted a greenhouse experiment to investigate how community composition and soil-atmosphere trace gas fluxes of CO2, CH4, and N2O varied from early-successional light cyanobacterial biocrusts to mid-successional dark cyanobacteria biocrusts and late-successional moss-lichen biocrusts and as biocrusts of each successional stage matured. Cover type richness increased as biocrusts developed, and richness was generally highest in the late-successional moss-lichen biocrusts. Microbial community composition varied in relation to successional stage, but microbial diversity did not differ significantly among stages. Net photosynthetic uptake of CO2 by each biocrust type also increased as biocrusts developed but tended to be moderately greater (by up to ≈25%) for the mid-successional dark cyanobacteria biocrusts than the light cyanobacterial biocrusts or the moss-lichen biocrusts. Rates of soil C accumulation were highest for the dark cyanobacteria biocrusts and light cyanobacteria biocrusts, and lowest for the moss-lichen biocrusts and bare soil controls. Biocrust CH4 and N2O fluxes were not consistently distinguishable from the same fluxes measured from bare soil controls; the measured rates were also substantially lower than have been reported in previous biocrust studies. Our experiment, which uniquely used greenhouse-grown biocrusts to manipulate community composition and accelerate biocrust development, shows how biocrust function varies along a dynamic gradient of biocrust successional stages.
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Affiliation(s)
- Andrew D. Richardson
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, United States
- *Correspondence: Andrew D. Richardson,
| | - Gary V. Kong
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, United States
- University of California, Santa Barbara, CA, United States
| | - Katrina M. Taylor
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, United States
- Department of Astronomy and Astrophysics, The Pennsylvania State University, State College, PA, United States
| | - James M. Le Moine
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, United States
| | - Matthew A. Bowker
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
- School of Forestry, Northern Arizona University, Flagstaff, AZ, United States
| | - Jarrett J. Barber
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, United States
| | - David Basler
- Department of Environmental Sciences–Botany, University of Basel, Basel, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Mariah S. Carbone
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
| | - Michaela Hayer
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
| | - George W. Koch
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
| | - Mark R. Salvatore
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, United States
| | - A. Wesley Sonnemaker
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, United States
- Lowell Observatory, Flagstaff, AZ, United States
| | - David E. Trilling
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, United States
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Peltier DMP, Guo J, Nguyen P, Bangs M, Wilson M, Samuels-Crow K, Yocom LL, Liu Y, Fell MK, Shaw JD, Auty D, Schwalm C, Anderegg WRL, Koch GW, Litvak ME, Ogle K. Temperature memory and non-structural carbohydrates mediate legacies of a hot drought in trees across the southwestern USA. Tree Physiol 2022; 42:71-85. [PMID: 34302167 DOI: 10.1093/treephys/tpab091] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 07/16/2021] [Indexed: 06/13/2023]
Abstract
Trees are long-lived organisms that integrate climate conditions across years or decades to produce secondary growth. This integration process is sometimes referred to as 'climatic memory.' While widely perceived, the physiological processes underlying this temporal integration, such as the storage and remobilization of non-structural carbohydrates (NSC), are rarely explicitly studied. This is perhaps most apparent when considering drought legacies (perturbed post-drought growth responses to climate), and the physiological mechanisms underlying these lagged responses to climatic extremes. Yet, drought legacies are likely to become more common if warming climate brings more frequent drought. To quantify the linkages between drought legacies, climate memory and NSC, we measured tree growth (via tree ring widths) and NSC concentrations in three dominant species across the southwestern USA. We analyzed these data with a hierarchical mixed effects model to evaluate the time-scales of influence of past climate (memory) on tree growth. We then evaluated the role of climate memory and the degree to which variation in NSC concentrations were related to forward-predicted growth during the hot 2011-2012 drought and subsequent 4-year recovery period. Populus tremuloides exhibited longer climatic memory compared to either Pinus edulis or Juniperus osteosperma, but following the 2011-2012 drought, P. tremuloides trees with relatively longer memory of temperature conditions showed larger (more negative) drought legacies. Conversely, Pinus edulis trees with longer temperature memory had smaller (less negative) drought legacies. For both species, higher NSC concentrations followed more negative (larger) drought legacies, though the relevant NSC fraction differed between P. tremuloides and P. edulis. Our results suggest that differences in tree NSC are also imprinted upon tree growth responses to climate across long time scales, which also underlie tree resilience to increasingly frequent drought events under climate change.
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Affiliation(s)
- Drew M P Peltier
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Jessica Guo
- Communications and Cyber Technologies, University of Arizona, Tucson, AZ 85721, USA
| | - Phiyen Nguyen
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Michael Bangs
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Michelle Wilson
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Kimberly Samuels-Crow
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Larissa L Yocom
- Department of Wildland Resources and the Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Yao Liu
- Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Michael K Fell
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - John D Shaw
- USDA Forest Service, Rocky Mountain Research Station, Ogden, UT 84401, USA
| | - David Auty
- School of Forestry, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Christopher Schwalm
- Woods Hole Research Center, Falmouth, MA 02540, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - George W Koch
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Marcy E Litvak
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Kiona Ogle
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
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5
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Williams CB, Reese Næsborg R, Ambrose AR, Baxter WL, Koch GW, Dawson TE. The dynamics of stem water storage in the tops of Earth's largest trees-Sequoiadendron giganteum. Tree Physiol 2021; 41:2262-2278. [PMID: 34104960 DOI: 10.1093/treephys/tpab078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 05/31/2021] [Indexed: 06/12/2023]
Abstract
Water stored in tree stems (i.e., trunks and branches) is an important contributor to transpiration that can improve photosynthetic carbon gain and reduce the probability of cavitation. However, in tall trees, the capacity to store water may decline with height because of chronically low water potentials associated with the gravitational potential gradient. We quantified the importance of elastic stem water storage in the top 5-6 m of large (4.2-5.0 m diameter at breast height, 82.1-86.3 m tall) Sequoiadendron giganteum (Lindley) J. Buchholz (giant sequoia) trees using a combination of architectural measurements and automated sensors that monitored summertime diel rhythms in sap flow, stem diameter and water potential. Stem water storage contributed 1.5-1.8% of water transpired at the tree tops, and hydraulic capacitance ranged from 2.6 to 4.1 l MPa-1 m-3. These values, which are considerably smaller than reported for shorter trees, may be associated with persistently low water potentials imposed by gravity and could indicate a trend of decreasing water storage dynamics with height in tree. Branch diameter contraction and expansion consistently and substantially lagged behind fluxes in water potential and sap flow, which occurred in sync. This lag suggests that the inner bark, which consists mostly of live secondary phloem tissue, was an important hydraulic capacitor, and that hydraulic resistance between xylem and phloem retards water transfer between these tissues. We also measured tree-base sap flux, which lagged behind that measured in trunks near the tree tops, indicating additional storage in the large trunks between these measurement positions. Whole-tree sap flow ranged from 2227 to 3752 l day-1, corroborating previous records for similar-sized giant sequoia and representing the largest yet reported for any individual tree. Despite such extraordinarily high daily water use, we estimate that water stored in tree-top stems contributes minimally to transpiration on typical summer days.
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Affiliation(s)
- Cameron B Williams
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- Channel Islands National Park, Ventura, CA 93001, USA
- Santa Barbara Botanic Garden, Santa Barbara, CA 93105, USA
| | - Rikke Reese Næsborg
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- Santa Barbara Botanic Garden, Santa Barbara, CA 93105, USA
| | - Anthony R Ambrose
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- The Marmot Society, South Lake Tahoe, CA 96150, USA
| | - Wendy L Baxter
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- The Marmot Society, South Lake Tahoe, CA 96150, USA
| | - George W Koch
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Todd E Dawson
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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6
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Peltier DMP, Guo J, Nguyen P, Bangs M, Gear L, Wilson M, Jefferys S, Samuels-Crow K, Yocom LL, Liu Y, Fell MK, Auty D, Schwalm C, Anderegg WRL, Koch GW, Litvak ME, Ogle K. Temporal controls on crown nonstructural carbohydrates in southwestern US tree species. Tree Physiol 2021; 41:388-402. [PMID: 33147630 DOI: 10.1093/treephys/tpaa149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
In trees, large uncertainties remain in how nonstructural carbohydrates (NSCs) respond to variation in water availability in natural, intact ecosystems. Variation in NSC pools reflects temporal fluctuations in supply and demand, as well as physiological coordination across tree organs in ways that differ across species and NSC fractions (e.g., soluble sugars vs starch). Using landscape-scale crown (leaves and twigs) NSC concentration measurements in three foundation tree species (Populus tremuloides, Pinus edulis, Juniperus osteosperma), we evaluated in situ, seasonal variation in NSC responses to moisture stress on three timescales: short-term (via predawn water potential), seasonal (via leaf δ13C) and annual (via current year's ring width index). Crown NSC responses to moisture stress appeared to depend on hydraulic strategy, where J. osteosperma appears to regulate osmotic potentials (via higher sugar concentrations), P. edulis NSC responses suggest respiratory depletion and P. tremuloides responses were consistent with direct sink limitations. We also show that overly simplistic models can mask seasonal and tissue variation in NSC responses, as well as strong interactions among moisture stress at different timescales. In general, our results suggest large seasonal variation in crown NSC concentrations reflecting the multiple cofunctions of NSCs in plant tissues, including storage, growth and osmotic regulation of hydraulically vulnerable leaves. We emphasize that crown NSC pool size cannot be viewed as a simple physiological metric of stress; in situ NSC dynamics are complex, varying temporally, across species, among NSC fractions and among tissue types.
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Affiliation(s)
- Drew M P Peltier
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Jessica Guo
- Geology and Geophysics, University of Utah, Salt Lake City, UT 84112, USA
| | - Phiyen Nguyen
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Michael Bangs
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Linnea Gear
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Michelle Wilson
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Stacy Jefferys
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Kimberly Samuels-Crow
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Larissa L Yocom
- Department of Wildland Resources and the Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Yao Liu
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Michael K Fell
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - David Auty
- School of Forestry, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Christopher Schwalm
- Woods Hole Research Center, Falmouth, MA 02540, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - George W Koch
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Marcy E Litvak
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Kiona Ogle
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
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7
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Duffy KA, Schwalm CR, Arcus VL, Koch GW, Liang LL, Schipper LA. How close are we to the temperature tipping point of the terrestrial biosphere? Sci Adv 2021; 7:7/3/eaay1052. [PMID: 33523891 PMCID: PMC7806211 DOI: 10.1126/sciadv.aay1052] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 11/20/2020] [Indexed: 05/19/2023]
Abstract
The temperature dependence of global photosynthesis and respiration determine land carbon sink strength. While the land sink currently mitigates ~30% of anthropogenic carbon emissions, it is unclear whether this ecosystem service will persist and, more specifically, what hard temperature limits, if any, regulate carbon uptake. Here, we use the largest continuous carbon flux monitoring network to construct the first observationally derived temperature response curves for global land carbon uptake. We show that the mean temperature of the warmest quarter (3-month period) passed the thermal maximum for photosynthesis during the past decade. At higher temperatures, respiration rates continue to rise in contrast to sharply declining rates of photosynthesis. Under business-as-usual emissions, this divergence elicits a near halving of the land sink strength by as early as 2040.
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Affiliation(s)
- Katharyn A Duffy
- School of Informatics, Computing and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA.
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Christopher R Schwalm
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
- Woods Hole Research Center, Falmouth, MA 02540, USA
| | - Vickery L Arcus
- School of Science, University of Waikato, Hamilton 3216, New Zealand
| | - George W Koch
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Liyin L Liang
- School of Science, University of Waikato, Hamilton 3216, New Zealand
- Manaaki Whenua-Landcare Research, Private Bag 11052, Palmerston North 4442, New Zealand
| | - Louis A Schipper
- School of Science, University of Waikato, Hamilton 3216, New Zealand
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8
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Guo JS, Gear L, Hultine KR, Koch GW, Ogle K. Non-structural carbohydrate dynamics associated with antecedent stem water potential and air temperature in a dominant desert shrub. Plant Cell Environ 2020; 43:1467-1483. [PMID: 32112440 DOI: 10.1111/pce.13749] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 02/14/2020] [Accepted: 02/21/2020] [Indexed: 06/10/2023]
Abstract
Non-structural carbohydrates (NSCs) are necessary for plant growth and affected by plant water status, but the temporal dynamics of water stress impacts on NSC are not well understood. We evaluated how seasonal NSC concentrations varied with plant water status (predawn xylem water potential, Ψ) and air temperature (T) in the evergreen desert shrub Larrea tridentata. Aboveground sugar and starch concentrations were measured weekly or monthly for ~1.5 years on 6-12 shrubs simultaneously instrumented with automated stem psychrometers; leaf photosynthesis (Anet ) was measured monthly for 1 year. Leaf sugar increased during the dry, premonsoon period, associated with lower Ψ (greater water stress) and high T. Leaf sugar accumulation coincided with declines in leaf starch and stem sugar, suggesting the prioritization of leaf sugar during low photosynthetic uptake. Leaf starch was strongly correlated with Anet and peaked during the spring and monsoon seasons, while stem starch remained relatively constant except for depletion during the monsoon. Recent photosynthate appeared sufficient to support spring growth, while monsoon growth required the remobilization of stem starch reserves. The coordinated responses of different NSC fractions to water status, photosynthesis, and growth demands suggest that NSCs serve multiple functions under extreme environmental conditions, including severe drought.
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Affiliation(s)
- Jessica S Guo
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Linnea Gear
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, Arizona, USA
| | - Kevin R Hultine
- Department of Research, Conservation, and Collections, Desert Botanical Garden, Phoenix, Arizona, USA
| | - George W Koch
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Kiona Ogle
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, Arizona, USA
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Guo JS, Hultine KR, Koch GW, Kropp H, Ogle K. Temporal shifts in iso/anisohydry revealed from daily observations of plant water potential in a dominant desert shrub. New Phytol 2020; 225:713-726. [PMID: 31519032 DOI: 10.1111/nph.16196] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 09/06/2019] [Indexed: 05/25/2023]
Abstract
Plant species are characterized along a spectrum of isohydry to anisohydry depending on their regulation of water potential (Ψ), but the plasticity of hydraulic strategies is largely unknown. The role of environmental drivers was evaluated in the hydraulic behavior of Larrea tridentata, a drought-tolerant desert shrub that withstands a wide range of environmental conditions. With a 1.5 yr time-series of 2324 in situ measurements of daily predawn and midday Ψ, the temporal variability of hydraulic behavior was explored in relation to soil water supply, atmospheric demand and temperature. Hydraulic behavior in Larrea was highly dynamic, ranging from partial isohydry to extreme anisohydry. Larrea exhibited extreme anisohydry under wet soil conditions corresponding to periods of high productivity, whereas partial isohydry was exhibited after prolonged dry or cold conditions, when productivity was low. Environmental conditions can strongly influence plant hydraulic behavior at relatively fast timescales, which enhances our understanding of plant drought responses. Although species may exhibit a dominant hydraulic behavior, variable environmental conditions can prompt plasticity in Ψ regulation, particularly for species in seasonally dry climates.
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Affiliation(s)
- Jessica S Guo
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Kevin R Hultine
- Department of Research, Conservation, and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA
| | - George W Koch
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Heather Kropp
- Department of Geography, Colgate University, Hamilton, NY, 13346, USA
| | - Kiona Ogle
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, 86011, USA
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Rubin RL, Koch GW, Martinez A, Mau RL, Bowker MA, Hungate BA. Developing climate-smart restoration: Can plant microbiomes be hardened against heat waves? Ecol Appl 2018; 28:1594-1605. [PMID: 29989265 DOI: 10.1002/eap.1763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 04/24/2018] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
Heat waves are increasing in frequency and intensity, presenting a challenge for the already difficult practice of ecological restoration. We investigated whether pre-heating locally sourced rhizosphere soil (inoculum) could acclimatize plants to a field-imposed heat wave in a restoration setting. Soil heating in the laboratory caused a marked shift in rhizosphere bacterial community composition, accompanied by an increase in species evenness. Furthermore, pre-heated rhizosphere soil reduced plant height, number of leaves, and shoot mass of the C4 grass, blue grama (Bouteloua gracilis), and it reduced the shoot mass of the C3 grass, Arizona fescue (Festuca arizonica) in the glasshouse. Following transplantation and the application of a field heat wave, pre-heated inoculum did not influence heat wave survival for either plant species. However, there were strong species-level responses to the field heat wave. For instance, heat wave survivorship was over four times higher in blue grama (92%) than in Arizona fescue (22%). These results suggest that the use of C4 seeds may be preferable for sites exhibiting high heat wave risk. Further research is needed to understand whether inocula are more effective in highly degraded soil in comparison with partially degraded soils.
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Affiliation(s)
- Rachel L Rubin
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, 86011, USA
| | - George W Koch
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, 86011, USA
| | - Ayla Martinez
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, 86011, USA
| | - Rebecca L Mau
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, 86011, USA
| | - Matthew A Bowker
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, 86011, USA
| | - Bruce A Hungate
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, 86011, USA
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11
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Siders AC, Compson ZG, Hungate BA, Dijkstra P, Koch GW, Wymore AS, Grandy AS, Marks JC. Litter identity affects assimilation of carbon and nitrogen by a shredding caddisfly. Ecosphere 2018. [DOI: 10.1002/ecs2.2340] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Adam C. Siders
- Center for Ecosystem Science and Society; Northern Arizona University; Flagstaff Arizona 86001 USA
- Department of Biological Sciences; Northern Arizona University; Flagstaff Arizona 86011 USA
| | - Zacchaeus G. Compson
- Canadian Rivers Institute; Department of Biology; University of New Brunswick; Fredericton NB E3B 5A3 Canada
- Environment and Climate Change Canada at Canadian Rivers Institute; Department of Biology; University of New Brunswick; Fredericton E3B 5A3 Canada
| | - Bruce A. Hungate
- Center for Ecosystem Science and Society; Northern Arizona University; Flagstaff Arizona 86001 USA
- Department of Biological Sciences; Northern Arizona University; Flagstaff Arizona 86011 USA
| | - Paul Dijkstra
- Center for Ecosystem Science and Society; Northern Arizona University; Flagstaff Arizona 86001 USA
- Department of Biological Sciences; Northern Arizona University; Flagstaff Arizona 86011 USA
| | - George W. Koch
- Center for Ecosystem Science and Society; Northern Arizona University; Flagstaff Arizona 86001 USA
- Department of Biological Sciences; Northern Arizona University; Flagstaff Arizona 86011 USA
| | - Adam S. Wymore
- Department of Natural Resources and the Environment; University of New Hampshire; Durham New Hampshire 03824 USA
| | - A. Stuart Grandy
- Department of Natural Resources and the Environment; University of New Hampshire; Durham New Hampshire 03824 USA
| | - Jane C. Marks
- Center for Ecosystem Science and Society; Northern Arizona University; Flagstaff Arizona 86001 USA
- Department of Biological Sciences; Northern Arizona University; Flagstaff Arizona 86011 USA
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12
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Compson ZG, Hungate BA, Whitham TG, Koch GW, Dijkstra P, Siders AC, Wojtowicz T, Jacobs R, Rakestraw DN, Allred KE, Sayer CK, Marks JC. Linking tree genetics and stream consumers: isotopic tracers elucidate controls on carbon and nitrogen assimilation. Ecology 2018; 99:1759-1770. [DOI: 10.1002/ecy.2224] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 01/30/2018] [Accepted: 02/09/2018] [Indexed: 12/27/2022]
Affiliation(s)
- Zacchaeus G. Compson
- Center for Ecosystem Science and Society; 800 S. Beaver Street, P.O. Box 5620 Flagstaff Arizona 86011-5620 USA
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Bruce A. Hungate
- Center for Ecosystem Science and Society; 800 S. Beaver Street, P.O. Box 5620 Flagstaff Arizona 86011-5620 USA
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Thomas G. Whitham
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - George W. Koch
- Center for Ecosystem Science and Society; 800 S. Beaver Street, P.O. Box 5620 Flagstaff Arizona 86011-5620 USA
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Paul Dijkstra
- Center for Ecosystem Science and Society; 800 S. Beaver Street, P.O. Box 5620 Flagstaff Arizona 86011-5620 USA
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Adam C. Siders
- Center for Ecosystem Science and Society; 800 S. Beaver Street, P.O. Box 5620 Flagstaff Arizona 86011-5620 USA
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Todd Wojtowicz
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Ryan Jacobs
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - David N. Rakestraw
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Kiel E. Allred
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Chelsea K. Sayer
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
| | - Jane C. Marks
- Center for Ecosystem Science and Society; 800 S. Beaver Street, P.O. Box 5620 Flagstaff Arizona 86011-5620 USA
- Merriam-Powell Center for Environmental Research; 800 S. Beaver Street, P.O. Box 6077 Flagstaff Arizona 86011-6077 USA
- Department of Biological Sciences; Northern Arizona University; 617 S. Beaver Street, P.O. Box 5640 Flagstaff Arizona 86011-5640 USA
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Affiliation(s)
- C. Josh Donlan
- Advanced Conservation Strategies; Córdoba Spain 14011
- Department of Ecology and Evolutionary Biology; Cornell University; Ithaca NY 14853 USA
| | | | - Chris Wilcox
- CSIRO Oceans and Atmosphere Business Unit; Hobart TAS 7000 Australia
| | - Stefan Gelcich
- Advanced Conservation Strategies; Córdoba Spain 14011
- Center of Applied Ecology and Sustainability & Centro de Conservacion Marina; Pontificia Universidad Catolica de Chile; Santiago Chile 8331150
| | - George W. Koch
- Department of Biological Sciences; Northern Arizona University; Flagstaff AZ 86011 USA
- Center for Ecosystem; Science and Society; Northern Arizona University; Flagstaff AZ 86011 USA
| | - Bruce A. Hungate
- Department of Biological Sciences; Northern Arizona University; Flagstaff AZ 86011 USA
- Center for Ecosystem; Science and Society; Northern Arizona University; Flagstaff AZ 86011 USA
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14
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Harrison JG, Forister ML, Parchman TL, Koch GW. Vertical stratification of the foliar fungal community in the world's tallest trees. Am J Bot 2016; 103:2087-2095. [PMID: 27965238 DOI: 10.3732/ajb.1600277] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 11/14/2016] [Indexed: 05/28/2023]
Abstract
PREMISE OF THE STUDY The aboveground tissues of plants host numerous, ecologically important fungi, yet patterns in the spatial distribution of these fungi remain little known. Forest canopies in particular are vast reservoirs of fungal diversity, but intracrown variation in fungal communities has rarely been explored. Knowledge of how fungi are distributed throughout tree crowns will contribute to our understanding of interactions between fungi and their host trees and is a first step toward investigating drivers of community assembly for plant-associated fungi. Here we describe spatial patterns in fungal diversity within crowns of the world's tallest trees, coast redwoods (Sequoia sempervirens). METHODS We took a culture-independent approach, using the Illumina MiSeq platform, to characterize the fungal assemblage at multiple heights within the crown across the geographical range of the coast redwood. KEY RESULTS Within each tree surveyed, we uncovered evidence for vertical stratification in the fungal community; different portions of the tree crown harbored different assemblages of fungi. We also report between-tree variation in the fungal community within redwoods. CONCLUSIONS Our results suggest the potential for vertical stratification of fungal communities in the crowns of other tall tree species and should prompt future study of the factors giving rise to this stratification.
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Affiliation(s)
- Joshua G Harrison
- Program in Ecology, Evolution, and Conservation Biology, Department of Biology, University of Nevada, Reno, 1664 North Virginia St., Nevada, USA
- Department of Biology, University of Nevada, Reno, 1664 North Virginia St., Nevada, USA
| | - Matthew L Forister
- Program in Ecology, Evolution, and Conservation Biology, Department of Biology, University of Nevada, Reno, 1664 North Virginia St., Nevada, USA
- Department of Biology, University of Nevada, Reno, 1664 North Virginia St., Nevada, USA
| | - Thomas L Parchman
- Program in Ecology, Evolution, and Conservation Biology, Department of Biology, University of Nevada, Reno, 1664 North Virginia St., Nevada, USA
- Department of Biology, University of Nevada, Reno, 1664 North Virginia St., Nevada, USA
| | - George W Koch
- Department of Biological Sciences, Northern Arizona University, 617 S. Beaver St., Flagstaff, Arizona, USA
- Center for Ecosystem Science and Society, Northern Arizona University, P.O. Box 5620, Flagstaff, Arizona, USA
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15
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Sack L, Ball MC, Brodersen C, Davis SD, Des Marais DL, Donovan LA, Givnish TJ, Hacke UG, Huxman T, Jansen S, Jacobsen AL, Johnson DM, Koch GW, Maurel C, McCulloh KA, McDowell NG, McElrone A, Meinzer FC, Melcher PJ, North G, Pellegrini M, Pockman WT, Pratt RB, Sala A, Santiago LS, Savage JA, Scoffoni C, Sevanto S, Sperry J, Tyerman SD, Way D, Holbrook NM. Plant hydraulics as a central hub integrating plant and ecosystem function: meeting report for 'Emerging Frontiers in Plant Hydraulics' (Washington, DC, May 2015). Plant Cell Environ 2016; 39:2085-94. [PMID: 27037757 DOI: 10.1111/pce.12732] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/06/2016] [Indexed: 05/25/2023]
Abstract
Water plays a central role in plant biology and the efficiency of water transport throughout the plant affects both photosynthetic rate and growth, an influence that scales up deterministically to the productivity of terrestrial ecosystems. Moreover, hydraulic traits mediate the ways in which plants interact with their abiotic and biotic environment. At landscape to global scale, plant hydraulic traits are important in describing the function of ecological communities and ecosystems. Plant hydraulics is increasingly recognized as a central hub within a network by which plant biology is connected to palaeobiology, agronomy, climatology, forestry, community and ecosystem ecology and earth-system science. Such grand challenges as anticipating and mitigating the impacts of climate change, and improving the security and sustainability of our food supply rely on our fundamental knowledge of how water behaves in the cells, tissues, organs, bodies and diverse communities of plants. A workshop, 'Emerging Frontiers in Plant Hydraulics' supported by the National Science Foundation, was held in Washington DC, 2015 to promote open discussion of new ideas, controversies regarding measurements and analyses, and especially, the potential for expansion of up-scaled and down-scaled inter-disciplinary research, and the strengthening of connections between plant hydraulic research, allied fields and global modelling efforts.
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Affiliation(s)
- Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Marilyn C Ball
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, 0200, Australia
| | - Craig Brodersen
- School of Forestry & Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
| | - Stephen D Davis
- Natural Science Division, Pepperdine University, Malibu, CA, 90263, USA
| | - David L Des Marais
- Arnold Arboretum, Harvard University, Cambridge, MA, 02131, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Boston, MA, 02138, USA
| | - Lisa A Donovan
- Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA
| | - Thomas J Givnish
- Department of Botany, University of Wisconsin Madison, Madison, WI, 53706, USA
| | - Uwe G Hacke
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada
| | - Travis Huxman
- Ecology and Evolutionary Biology & Center for Environmental Biology, University of California, Irvine, CA, 92697, USA
| | - Steven Jansen
- Ulm University, Institute of Systematic Botany and Ecology, Albert-Einstein-Allee 11, Ulm, 89081, Germany
| | - Anna L Jacobsen
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Daniel M Johnson
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, ID, 83844, USA
| | - George W Koch
- Center for Ecosystem Science and Society, and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Christophe Maurel
- Biochimie et Physiologie Moléculaire des Plantes, UMR 5004, INRA-CNRS-Sup Agro-Université de Montpellier, 2 Place Viala, Montpellier, F-34060, France
| | | | - Nate G McDowell
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Andrew McElrone
- Department of Viticulture and Enology, University of California, Davis, CA, 95616, USA
- USDA-Agricultural Research Service, Davis, CA, 95616, USA
| | - Frederick C Meinzer
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, OR, 97331, USA
| | - Peter J Melcher
- Department of Biology, Ithaca College, Ithaca, NY, 14850, USA
| | - Gretchen North
- Department of Biology, Occidental College, Los Angeles, CA, 90041, USA
| | - Matteo Pellegrini
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - William T Pockman
- Department of Biology, MSC03 2020, University of New Mexico, Albuquerque, NM, 87131, USA
| | - R Brandon Pratt
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Anna Sala
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Louis S Santiago
- Botany and Plant Sciences, University of California, Riverside, CA, 92521, USA
| | - Jessica A Savage
- Arnold Arboretum, Harvard University, Cambridge, MA, 02131, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Boston, MA, 02138, USA
| | - Christine Scoffoni
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - John Sperry
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT, 84112, USA
| | - Stephen D Tyerman
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Precinct, The University of Adelaide, PMB 1, Glen Osmond, South Australia, 5064, Australia
| | - Danielle Way
- Department of Biology, Western University, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada
| | - N Michele Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Boston, MA, 02138, USA
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Ambrose AR, Baxter WL, Wong CS, Burgess SSO, Williams CB, Næsborg RR, Koch GW, Dawson TE. Hydraulic constraints modify optimal photosynthetic profiles in giant sequoia trees. Oecologia 2016; 182:713-30. [DOI: 10.1007/s00442-016-3705-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 08/12/2016] [Indexed: 01/09/2023]
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Hurteau MD, Liang S, Martin KL, North MP, Koch GW, Hungate BA. Restoring forest structure and process stabilizes forest carbon in wildfire-prone southwestern ponderosa pine forests. Ecol Appl 2016; 26:382-391. [PMID: 27209781 DOI: 10.1890/15-0337] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Changing climate and a legacy of fire-exclusion have increased the probability of high-severity wildfire, leading to an increased risk of forest carbon loss in ponderosa pine forests in the southwestern USA. Efforts to reduce high-severity fire risk through forest thinning and prescribed burning require both the removal and emission of carbon from these forests, and any potential carbon benefits from treatment may depend on the occurrence of wildfire. We sought to determine how forest treatments alter the effects of stochastic wildfire events on the forest carbon balance. We modeled three treatments (control, thin-only, and thin and burn) with and without the occurrence of wildfire. We evaluated how two different probabilities of wildfire occurrence, 1% and 2% per year, might alter the carbon balance of treatments. In the absence of wildfire, we found that thinning and burning treatments initially reduced total ecosystem carbon (TEC) and increased net ecosystem carbon balance (NECB). In the presence of wildfire, the thin and burn treatment TEC surpassed that of the control in year 40 at 2%/yr wildfire probability, and in year 51 at 1%/yr wildfire probability. NECB in the presence of wildfire showed a similar response to the no-wildfire scenarios: both thin-only and thin and burn treatments increased the C sink. Treatments increased TEC by reducing both mean wildfire severity and its variability. While the carbon balance of treatments may differ in more productive forest types, the carbon balance benefits from restoring forest structure and fire in southwestern ponderosa pine forests are clear.
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Martin KL, Hurteau MD, Hungate BA, Koch GW, North MP. Carbon Tradeoffs of Restoration and Provision of Endangered Species Habitat in a Fire-Maintained Forest. Ecosystems 2014. [DOI: 10.1007/s10021-014-9813-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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McHugh TA, Koch GW, Schwartz E. Minor changes in soil bacterial and fungal community composition occur in response to monsoon precipitation in a semiarid grassland. Microb Ecol 2014; 68:370-378. [PMID: 24743883 DOI: 10.1007/s00248-014-0416-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 04/01/2014] [Indexed: 06/03/2023]
Abstract
Arizona and New Mexico receive half of their annual precipitation during the summer monsoon season, making this large-scale rain event critical for ecosystem productivity. We used the monsoon rains to explore the responses of soil bacterial and fungal communities to natural moisture pulses in a semiarid grassland. Through 454 pyrosequencing of the 16S rRNA gene and ITS region, we phylogenetically characterized these communities at 22 time points during a summer season. Relative humidity increased before the rains arrived, creating conditions in soil that allowed for the growth of microorganisms. During the course of the study, the relative abundances of most bacterial phyla showed little variation, though some bacterial populations responded immediately to an increase in soil moisture once the monsoon rains arrived. The Firmicutes phylum experienced over a sixfold increase in relative abundance with increasing water availability. Conversely, Actinobacteria, the dominant taxa at our site, were negatively affected by the increase in water availability. No relationship was found between bacterial diversity and soil water potential. Bacterial community structure was unrelated to all environmental variables that we measured, with the exception of a significant relationship with atmospheric relative humidity. Relative abundances of fungal phyla fluctuated more throughout the season than bacterial abundances did. Variation in fungal community structure was unrelated to soil water potential and to most environmental variables. However, ordination analysis showed a distinct fungal community structure late in the season, probably due to plant senescence.
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Affiliation(s)
- Theresa A McHugh
- Department of Biological Sciences, Northern Arizona University, P.O. Box 5640, Flagstaff, AZ, 86011, USA,
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20
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Affiliation(s)
- Lucy P. Kerhoulas
- Department of Biological Sciences; Merriam-Powell Center for Environmental Research; Northern Arizona University; P.O. Box 5640 Flagstaff AZ 86011 USA
| | - Thomas E. Kolb
- School of Forestry; Northern Arizona University; P.O. Box 15018 Flagstaff AZ 86011 USA
| | - Matthew D. Hurteau
- Department of Ecosystem Science and Management; Pennsylvania State University; 306 Forest Resources Building University Park PA 16802 USA
| | - George W. Koch
- Department of Biological Sciences; Merriam-Powell Center for Environmental Research; Northern Arizona University; P.O. Box 5640 Flagstaff AZ 86011 USA
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21
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Classen AT, Chapman SK, Whitham TG, Hart SC, Koch GW. Long-term insect herbivory slows soil development in an arid ecosystem. Ecosphere 2013. [DOI: 10.1890/es12-00411.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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22
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Chapman SK, Newman GS, Hart SC, Schweitzer JA, Koch GW. Leaf litter mixtures alter microbial community development: mechanisms for non-additive effects in litter decomposition. PLoS One 2013; 8:e62671. [PMID: 23658639 PMCID: PMC3639160 DOI: 10.1371/journal.pone.0062671] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 03/24/2013] [Indexed: 11/19/2022] Open
Abstract
To what extent microbial community composition can explain variability in ecosystem processes remains an open question in ecology. Microbial decomposer communities can change during litter decomposition due to biotic interactions and shifting substrate availability. Though relative abundance of decomposers may change due to mixing leaf litter, linking these shifts to the non-additive patterns often recorded in mixed species litter decomposition rates has been elusive, and links community composition to ecosystem function. We extracted phospholipid fatty acids (PLFAs) from single species and mixed species leaf litterbags after 10 and 27 months of decomposition in a mixed conifer forest. Total PLFA concentrations were 70% higher on litter mixtures than single litter types after 10 months, but were only 20% higher after 27 months. Similarly, fungal-to-bacterial ratios differed between mixed and single litter types after 10 months of decomposition, but equalized over time. Microbial community composition, as indicated by principal components analyses, differed due to both litter mixing and stage of litter decomposition. PLFA biomarkers a15∶0 and cy17∶0, which indicate gram-positive and gram-negative bacteria respectively, in particular drove these shifts. Total PLFA correlated significantly with single litter mass loss early in decomposition but not at later stages. We conclude that litter mixing alters microbial community development, which can contribute to synergisms in litter decomposition. These findings advance our understanding of how changing forest biodiversity can alter microbial communities and the ecosystem processes they mediate.
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Affiliation(s)
- Samantha K Chapman
- Department of Biology, Villanova University, Villanova, Pennsylvania, USA.
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Dore S, Montes-Helu M, Hart SC, Hungate BA, Koch GW, Moon JB, Finkral AJ, Kolb TE. Recovery of ponderosa pine ecosystem carbon and water fluxes from thinning and stand-replacing fire. Glob Chang Biol 2012; 18:3171-3185. [PMID: 28741823 DOI: 10.1111/j.1365-2486.2012.02775.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 05/07/2012] [Indexed: 05/13/2023]
Abstract
Carbon uptake by forests is a major sink in the global carbon cycle, helping buffer the rising concentration of CO2 in the atmosphere, yet the potential for future carbon uptake by forests is uncertain. Climate warming and drought can reduce forest carbon uptake by reducing photosynthesis, increasing respiration, and by increasing the frequency and intensity of wildfires, leading to large releases of stored carbon. Five years of eddy covariance measurements in a ponderosa pine (Pinus ponderosa)-dominated ecosystem in northern Arizona showed that an intense wildfire that converted forest into sparse grassland shifted site carbon balance from sink to source for at least 15 years after burning. In contrast, recovery of carbon sink strength after thinning, a management practice used to reduce the likelihood of intense wildfires, was rapid. Comparisons between an undisturbed-control site and an experimentally thinned site showed that thinning reduced carbon sink strength only for the first two posttreatment years. In the third and fourth posttreatment years, annual carbon sink strength of the thinned site was higher than the undisturbed site because thinning reduced aridity and drought limitation to carbon uptake. As a result, annual maximum gross primary production occurred when temperature was 3 °C higher at the thinned site compared with the undisturbed site. The severe fire consistently reduced annual evapotranspiration (range of 12-30%), whereas effects of thinning were smaller and transient, and could not be detected in the fourth year after thinning. Our results show large and persistent effects of intense fire and minor and short-lived effects of thinning on southwestern ponderosa pine ecosystem carbon and water exchanges.
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Affiliation(s)
- Sabina Dore
- School of Forestry, Northern Arizona University, PO Box 15018, Flagstaff, AZ, 86011-5018, USA
| | - Mario Montes-Helu
- School of Forestry, Northern Arizona University, PO Box 15018, Flagstaff, AZ, 86011-5018, USA
| | - Stephen C Hart
- School of Natural Sciences and Sierra Nevada Research Institute, University of California, Merced, CA, 95344, USA
| | - Bruce A Hungate
- Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - George W Koch
- Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - John B Moon
- School of Forestry, Northern Arizona University, PO Box 15018, Flagstaff, AZ, 86011-5018, USA
| | - Alex J Finkral
- School of Forestry, Northern Arizona University, PO Box 15018, Flagstaff, AZ, 86011-5018, USA
| | - Thomas E Kolb
- School of Forestry, Northern Arizona University, PO Box 15018, Flagstaff, AZ, 86011-5018, USA
- Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, 86011, USA
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Ambrose AR, Sillett SC, Koch GW, Van Pelt R, Antoine ME, Dawson TE. Effects of height on treetop transpiration and stomatal conductance in coast redwood (Sequoia sempervirens). Tree Physiol 2010; 30:1260-1272. [PMID: 20631010 DOI: 10.1093/treephys/tpq064] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Treetops become increasingly constrained by gravity-induced water stress as they approach maximum height. Here we examine the effects of height on seasonal and diurnal sap flow dynamics at the tops of 12 unsuppressed Sequoia sempervirens (D. Don) Endl. (coast redwood) trees 68-113 m tall during one growing season. Average treetop sap velocity (V(S)), transpiration per unit leaf area (E(L)) and stomatal conductance per unit leaf area (G(S)) significantly decreased with increasing height. These differences in sap flow were associated with an unexpected decrease in treetop sapwood area-to-leaf area ratios (A(S):A(L)) in the tallest trees. Both E(L) and G(S) declined as soil moisture decreased and vapor pressure deficit (D) increased throughout the growing season with a greater decline in shorter trees. Under high soil moisture and light conditions, reference G(S) (G(Sref); G(S) at D = 1 kPa) and sensitivity of G(S) to D (-δ; dG(S)/dlnD) significantly decreased with increasing height. The close relationship we observed between G(Sref) and -δ is consistent with the role of stomata in regulating E(L) and leaf water potential (Ψ(L)). Our results confirm that increasing tree height reduces gas exchange of treetop foliage and thereby contributes to lower carbon assimilation and height growth rates as S. sempervirens approaches maximum height.
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Affiliation(s)
- Anthony R Ambrose
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
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Oldham AR, Sillett SC, Tomescu AMF, Koch GW. The hydrostatic gradient, not light availability, drives height-related variation in Sequoia sempervirens (Cupressaceae) leaf anatomy. Am J Bot 2010; 97:1087-1097. [PMID: 21616861 DOI: 10.3732/ajb.0900214] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
PREMISE OF THE STUDY Leaves at the tops of most trees are smaller, thicker, and in many other ways different from leaves on the lowermost branches. This height-related variation in leaf structure has been explained as acclimation to differing light environments and, alternatively, as a consequence of hydrostatic, gravitational constraints on turgor pressure that reduce leaf expansion. • METHODS To separate hydrostatic effects from those of light availability, we used anatomical analysis of height-paired samples from the inner and outer tree crowns of tall redwoods (Sequoia sempervirens). • KEY RESULTS Height above the ground correlates much more strongly with leaf anatomy than does light availability. Leaf length, width, and mesophyll porosity all decrease linearly with height and help explain increases in leaf-mass-to-area ratio and decreases in both photosynthetic capacity and internal gas-phase conductance with increasing height. Two functional traits-leaf thickness and transfusion tissue-also increase with height and may improve water-stress tolerance. Transfusion tissue area increases enough that whole-leaf vascular volume does not change significantly with height in most trees. Transfusion tracheids become deformed with height, suggesting they may collapse under water stress and act as a hydraulic buffer that improves leaf water status and reduces the likelihood of xylem dysfunction. • CONCLUSIONS That such variation in leaf structure may be caused more by gravity than by light calls into question use of the terms "sun" and "shade" to describe leaves at the tops and bottoms of tall tree crowns.
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Affiliation(s)
- Alana R Oldham
- Department of Biological Sciences, Humboldt State University, Arcata, California 95521 USA
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Dore S, Kolb TE, Montes-Helu M, Eckert SE, Sullivan BW, Hungate BA, Kaye JP, Hart SC, Koch GW, Finkral A. Carbon and water fluxes from ponderosa pine forests disturbed by wildfire and thinning. Ecol Appl 2010; 20:663-683. [PMID: 20437955 DOI: 10.1890/09-0934.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Disturbances alter ecosystem carbon dynamics, often by reducing carbon uptake and stocks. We compared the impact of two types of disturbances that represent the most likely future conditions of currently dense ponderosa pine forests of the southwestern United States: (1) high-intensity fire and (2) thinning, designed to reduce fire intensity. High-severity fire had a larger impact on ecosystem carbon uptake and storage than thinning. Total ecosystem carbon was 42% lower at the intensely burned site, 10 years after burning, than at the undisturbed site. Eddy covariance measurements over two years showed that the burned site was a net annual source of carbon to the atmosphere whereas the undisturbed site was a sink. Net primary production (NPP), evapotranspiration (ET), and water use efficiency were lower at the burned site than at the undisturbed site. In contrast, thinning decreased total ecosystem carbon by 18%, and changed the site from a carbon sink to a source in the first posttreatment year. Thinning also decreased ET, reduced the limitation of drought on carbon uptake during summer, and did not change water use efficiency. Both disturbances reduced ecosystem carbon uptake by decreasing gross primary production (55% by burning, 30% by thinning) more than total ecosystem respiration (TER; 33-47% by burning, 18% by thinning), and increased the contribution of soil carbon dioxide efflux to TER. The relationship between TER and temperature was not affected by either disturbance. Efforts to accurately estimate regional carbon budgets should consider impacts on carbon dynamics of both large disturbances, such as high-intensity fire, and the partial disturbance of thinning that is often used to prevent intense burning. Our results show that thinned forests of ponderosa pine in the southwestern United States are a desirable alternative to intensively burned forests to maintain carbon stocks and primary production.
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Affiliation(s)
- S Dore
- School of Forestry, Northern Arizona University, P.O. Box 15018, Flagstaff, Arizona 86011-5018, USA.
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Mullin LP, Sillett SC, Koch GW, Tu KP, Antoine ME. Physiological consequences of height-related morphological variation in Sequoia sempervirens foliage. Tree Physiol 2009; 29:999-1010. [PMID: 19483187 DOI: 10.1093/treephys/tpp037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This study examined relationships between foliar morphology and gas exchange characteristics as they vary with height within and among crowns of Sequoia sempervirens D. Don trees ranging from 29 to 113 m in height. Shoot mass:area (SMA) ratio increased with height and was less responsive to changes in light availability as height increased, suggesting a transition from light to water relations as the primary determinant of morphology with increasing height. Mass-based rates of maximum photosynthesis (A(max,m)), standardized photosynthesis (A(std,m)) and internal CO(2) conductance (g(i,m)) decreased with height and SMA, while the light compensation point, light saturation point, and mass and area-based rates of dark respiration (R(m)) increased with height and SMA. Among foliage from different heights, much of the variation in standardized photosynthesis was explained by variation in g(i,) consistent with increasing limitation of photosynthesis by internal conductance in foliage with higher SMA. The syndrome of lower internal and stomatal conductance to CO(2) and higher respiration may contribute to reductions in upper crown growth efficiency with increasing height in S. sempervirens trees.
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Affiliation(s)
- Lucy P Mullin
- Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ 86011, USA.
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Abstract
Here we respond to the communication in American Journal of Botany (96: 542-544 in this issue) by Netting, who proposes several ways in which our paper "The Limits to Tree Height" (Nature 428: 851-854) may have erred in estimating the biophysical limits to height growth in Sequoia sempervirens. We first explain that because embolism repair requires long time periods and is generally incomplete, xylem vulnerability characteristics offer a sound basis for estimating performance limits in woody plants. We reaffirm our earlier use of vertical gradients of foliar carbon isotope composition with new data for S. sempervirens. We support these arguments with reference to studies in other tree species. We take exception with Netting's view that the turgor pressure-cell expansion relationship for Zea mays is applicable to S. sempervirens. Finally, we second Netting's call for more work on carbon allocation vis a vis height growth limits.
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Affiliation(s)
- George W Koch
- Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011 USA
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Hurteau MD, Hungate BA, Koch GW. Accounting for risk in valuing forest carbon offsets. Carbon Balance Manag 2009; 4:1. [PMID: 19149889 PMCID: PMC2651132 DOI: 10.1186/1750-0680-4-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 01/16/2009] [Indexed: 05/27/2023]
Abstract
BACKGROUND Forests can sequester carbon dioxide, thereby reducing atmospheric concentrations and slowing global warming. In the U.S., forest carbon stocks have increased as a result of regrowth following land abandonment and in-growth due to fire suppression, and they currently sequester approximately 10% of annual US emissions. This ecosystem service is recognized in greenhouse gas protocols and cap-and-trade mechanisms, yet forest carbon is valued equally regardless of forest type, an approach that fails to account for risk of carbon loss from disturbance. RESULTS Here we show that incorporating wildfire risk reduces the value of forest carbon depending on the location and condition of the forest. There is a general trend of decreasing risk-scaled forest carbon value moving from the northern toward the southern continental U.S. CONCLUSION Because disturbance is a major ecological factor influencing long-term carbon storage and is often sensitive to human management, carbon trading mechanisms should account for the reduction in value associated with disturbance risk.
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Affiliation(s)
- Matthew D Hurteau
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, PO Box 6077, Flagstaff, AZ 86011, USA
| | - Bruce A Hungate
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, PO Box 6077, Flagstaff, AZ 86011, USA
| | - George W Koch
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, PO Box 6077, Flagstaff, AZ 86011, USA
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Cavagnaro TR, Langley AJ, Jackson LE, Smukler SM, Koch GW. Growth, nutrition, and soil respiration of a mycorrhiza-defective tomato mutant and its mycorrhizal wild-type progenitor. Funct Plant Biol 2008; 35:228-235. [PMID: 32688777 DOI: 10.1071/fp07281] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Accepted: 03/13/2008] [Indexed: 06/11/2023]
Abstract
The effects of colonisation of roots by arbuscular mycorrhizal fungi (AMF) on soil respiration, plant growth, nutrition, and soil microbial communities were assessed using a mycorrhiza-defective tomato (Solanum lycopersicum L.) mutant and its mycorrhizal wild-type progenitor. Plants were grown in rhizocosms in an automated respiration monitoring system over the course of the experiment (79 days). Soil respiration was similar in the two tomato genotypes, and between P treatments with plants. Mycorrhizal colonisation increased P and Zn content and decreased root biomass, but did not affect aboveground plant biomass. Soil microbial biomass C and soil microbial communities based on phospholipid fatty acid (PLFA) analysis were similar across all treatments, suggesting that the two genotypes differed little in their effect on soil activity. Although approximately similar amounts of C may have been expended belowground in both genotypes, they may have differed in the relative C allocation to root construction v. respiration. Further, net soil respiration did not differ between the two tomato genotypes, but root dry weight was lower in mycorrhizal roots, and respiration of mycorrhizal roots per unit dry weight was higher than nonmycorrhizal roots. This indicates that the AM contribution to soil respiration may indeed be significant, and nutrient uptake per unit C expenditure belowground in this experiment appeared to be higher in mycorrhizal plants.
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Affiliation(s)
- Timothy R Cavagnaro
- School of Biological Sciences and Australian Centre for Biodiversity, Monash University, Clayton, Vic. 3800, Australia
| | - Adam J Langley
- Smithsonian Environmental Research Centre, Edgewater, MD 21037, USA
| | - Louise E Jackson
- Department of Land, Air and Water Resources, University of California Davis, One Shields Avenue, Davis, CA 95616-8627, USA
| | - Sean M Smukler
- Department of Land, Air and Water Resources, University of California Davis, One Shields Avenue, Davis, CA 95616-8627, USA
| | - George W Koch
- National Institute for Climatic Change Research, Box 5640, Northern Arizona University, Flagstaff, AZ 86011, USA
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Ishii HT, Jennings GM, Sillett SC, Koch GW. Hydrostatic constraints on morphological exploitation of light in tall Sequoia sempervirens trees. Oecologia 2008; 156:751-63. [DOI: 10.1007/s00442-008-1032-z] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Accepted: 03/17/2008] [Indexed: 11/30/2022]
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Simonin K, Kolb TE, Montes-Helu M, Koch GW. Restoration thinning and influence of tree size and leaf area to sapwood area ratio on water relations of Pinus ponderosa. Tree Physiol 2006; 26:493-503. [PMID: 16414928 DOI: 10.1093/treephys/26.4.493] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Ponderosa pine (Pinus ponderosa Dougl. ex P. Laws) forest stand density has increased significantly over the last century (Covington et al. 1997). To understand the effect of increased intraspecific competition, tree size (height and diameter at breast height (DBH)) and leaf area to sapwood area ratio (A(L):A(S)) on water relations, we compared hydraulic conductance from soil to leaf (kl) and transpiration per unit leaf area (Q(L)) of ponderosa pine trees in an unthinned plot to trees in a thinned plot in the first and second years after thinning in a dense Arizona forest. We calculated kl and Q(L) based on whole- tree sap flux measured with heat dissipation sensors. Thinning increased tree predawn water potential within two weeks of treatment. Effects of thinning on kl and Q(L) depended on DBH, A(L):A(S) and drought severity. During severe drought in the first growing season after thinning, kl and Q(L) of trees with low A(L):A(S) (160-250 mm DBH; 9-11 m height) were lower in the thinned plot than the unthinned plot, suggesting a reduction in stomatal conductance (g(s)) or reduced sapwood specific conductivity (K(S)), or both, in response to thinning. In contrast kl and Q(L) were similar in the thinned plot and unthinned plot for trees with high A(L):A(S) (260-360 mm DBH; 13-16 m height). During non-drought periods, kl and Q(L) were greater in the thinned plot than in the unthinned plot for all but the largest trees. Contrary to previous studies of ponderosa pine, A(L):A(S) was positively correlated with tree height and DBH. Furthermore, kl and Q(L) showed a weak negative correlation with tree height and a strong negative correlation with A(S) and thus A(L):A(S) in both the thinned and unthinned plots, suggesting that trees with high A(L):A(S) had lower g(s). Our results highlight the important influence of stand competitive environment on tree-size-related variation in A(L):A(S) and the roles of A(L):A(S) and drought on whole-tree water relations in response to thinning.
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Affiliation(s)
- K Simonin
- School of Forestry, Northern Arizona University, Flagstaff AZ, 86011-5018, USA.
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Abstract
Ecologists have tried to link plant species composition and ecosystem properties since the inception of the ecosystem concept in ecology. Many have observed that biological communities could feed back to, and not simply result from, soil properties. But which group of organisms, plants or microorganisms, drive those feedback systems? Recent research asserts that soil microorganisms preclude plant species feedback to soil nitrogen (N) transformations due to strong microbial control of soil N cycling. It has been well documented that litter properties influence soil N cycling. In this review, we stress that under many circumstances plant species exert a major influence over soil N cycling rates via unique N attainment strategies, thus influencing soil N availability and their own fitness. We offer two testable mechanisms by which plants impart active control on the N cycle and thereby allow for plant-litter-soil-plant feedback. Finally, we describe the characteristics of plants and ecosystems that are most likely to exhibit feedback.
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Affiliation(s)
- Samantha K Chapman
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA.
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Huxman TE, Smith MD, Fay PA, Knapp AK, Shaw MR, Loik ME, Smith SD, Tissue DT, Zak JC, Weltzin JF, Pockman WT, Sala OE, Haddad BM, Harte J, Koch GW, Schwinning S, Small EE, Williams DG. Convergence across biomes to a common rain-use efficiency. Nature 2004; 429:651-4. [PMID: 15190350 DOI: 10.1038/nature02561] [Citation(s) in RCA: 386] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2004] [Accepted: 04/15/2004] [Indexed: 11/08/2022]
Abstract
Water availability limits plant growth and production in almost all terrestrial ecosystems. However, biomes differ substantially in sensitivity of aboveground net primary production (ANPP) to between-year variation in precipitation. Average rain-use efficiency (RUE; ANPP/precipitation) also varies between biomes, supposedly because of differences in vegetation structure and/or biogeochemical constraints. Here we show that RUE decreases across biomes as mean annual precipitation increases. However, during the driest years at each site, there is convergence to a common maximum RUE (RUE(max)) that is typical of arid ecosystems. RUE(max) was also identified by experimentally altering the degree of limitation by water and other resources. Thus, in years when water is most limiting, deserts, grasslands and forests all exhibit the same rate of biomass production per unit rainfall, despite differences in physiognomy and site-level RUE. Global climate models predict increased between-year variability in precipitation, more frequent extreme drought events, and changes in temperature. Forecasts of future ecosystem behaviour should take into account this convergent feature of terrestrial biomes.
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Affiliation(s)
- Travis E Huxman
- Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
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Abstract
Trees grow tall where resources are abundant, stresses are minor, and competition for light places a premium on height growth. The height to which trees can grow and the biophysical determinants of maximum height are poorly understood. Some models predict heights of up to 120 m in the absence of mechanical damage, but there are historical accounts of taller trees. Current hypotheses of height limitation focus on increasing water transport constraints in taller trees and the resulting reductions in leaf photosynthesis. We studied redwoods (Sequoia sempervirens), including the tallest known tree on Earth (112.7 m), in wet temperate forests of northern California. Our regression analyses of height gradients in leaf functional characteristics estimate a maximum tree height of 122-130 m barring mechanical damage, similar to the tallest recorded trees of the past. As trees grow taller, increasing leaf water stress due to gravity and path length resistance may ultimately limit leaf expansion and photosynthesis for further height growth, even with ample soil moisture.
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Affiliation(s)
- George W Koch
- Department of Biological Sciences and the Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, Arizona 86011, USA.
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Chapman SK, Hart SC, Cobb NS, Whitham TG, Koch GW. INSECT HERBIVORY INCREASES LITTER QUALITY AND DECOMPOSITION: AN EXTENSION OF THE ACCELERATION HYPOTHESIS. Ecology 2003. [DOI: 10.1890/02-0046] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Palermo BL, Clancy KM, Koch GW. The potential role of ectomycorrhizal fungi in determining Douglas-fir resistance to defoliation by the western spruce budworm (Lepidoptera: Tortricidae). J Econ Entomol 2003; 96:783-791. [PMID: 12852617 DOI: 10.1603/0022-0493-96.3.783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
There is phenotypic variation among individual trees of interior Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) in their resistance to defoliation by the western spruce budworm (Choristoneura occidentalis Freeman). We evaluated the potential role of ectomycorrhizal fungi in determining this resistance using half-sib seedlings derived from parent trees that are resistant versus susceptible to budworm defoliation in the field. The seedlings were inoculated with Laccaria bicolor ectomycorrhizal fungi, fertilized, or untreated. Approximately 48 d after treatment, late-instar larvae from a nondiapausing laboratory colony of C. occidentalis were allowed to feed on pairs of resistant versus susceptible seedlings for 1 wk. Chemical analyses of current-year shoots for nitrogen (N), phosphorus (P), magnesium (Mg), and zinc (Zn) indicated that the fungus increased foliar concentrations of P and Mg in resistant seedlings, but it did not increase their growth rate. However, L. bicolor had no effect on foliar concentrations of P or Mg in susceptible seedlings, even though seedling growth rates increased slightly in response to the inoculation. L. bicolor had no effect on foliar levels of N or Zn in any of the seedlings. As expected, fertilization increased levels of N and P in the foliage of both resistant and susceptible seedlings, but it did not affect levels of Mg and Zn. Surprisingly, the fertilizer treatment had no effect on seedling growth rates. Despite these differences, late-instar budworms showed no feeding preference among untreated, mycorrhizal, or fertilized seedlings. The fact that seedlings from resistant versus susceptible Douglas-firs responded differently to the L. bicolor treatment lends preliminary support to the hypothesis that ecotmycorrhizae might play a role in Douglas-fir resistance to damage from the western spruce budworm. Finally, differences in foliar concentrations of N and P among untreated seedlings from different maternal trees suggested that foliar nutritional chemistry is influenced by the tree's genotype.
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Affiliation(s)
- Barbara L Palermo
- Department of Biological Sciences, Northern Arizona University, P.O. Box 5640, Flagstaff, AZ 86011-5640, USA
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Abstract
Elevated CO(2), in the dark, is sometimes reported to inhibit leaf respiration, with respiration usually measured as CO(2) efflux. Oxygen uptake may be a better gauge of respiration because non-respiratory processes can affect dark CO(2) efflux in elevated CO(2). Two methods of quantifying O(2) uptake indicated that leaf respiration was unaffected by coincident CO(2) level in the dark.
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Affiliation(s)
- J S Amthor
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Koch GW, Vitousek PM, Steffen WL, Walker BH. Terrestrial transects for global change research. Global change and terrestrial ecosystems in monsoon Asia 1995. [DOI: 10.1007/978-94-011-0343-5_6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Koch GW, Amthor JS, Goulden ML. Diurnal patterns of leaf photosynthesis, conductance and water potential at the top of a lowland rain forest canopy in Cameroon: measurements from the Radeau des Cimes. Tree Physiol 1994; 14:347-360. [PMID: 14967691 DOI: 10.1093/treephys/14.4.347] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Diurnal patterns of leaf conductance, net photosynthesis and water potential of five tree species were measured at the top of the canopy in a tropical lowland rain forest in southwestern Cameroon. Access to the 40 m canopy was by a large canopy-supported raft, the Radeau des Cimes. The measurements were made under ambient conditions, but the raft altered the local energy balance at times, resulting in elevated leaf temperatures. Leaf water potential was equal to or greater than the gravitational potential at 40 m in the early morning, falling to values as low as -3.0 MPa near midday. Net photosynthesis and conductance were typically highest during midmorning, with values of about 10-12 micro mol CO(2) m(-2) s(-1) and 0.2-0.3 mol H(2)O m(-2) s(-1), respectively. Leaf conductance and net photosynthesis commonly declined through midday with occasional recovery late in the day. Photosynthesis was negatively related to leaf temperature above midday air temperature maxima. These patterns were similar to those observed in other seasonally droughted evergreen communities, such as Mediterranean-climate shrubs, and indicate that environmental factors may cause stomatal closure and limit photosynthesis in tropical rain forests during the midday period.
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Affiliation(s)
- G W Koch
- Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA
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Abstract
Curly dock (Rumex crispus L.) was grown from seed in a glasshouse at an ambient CO(2) partial pressure of about 35 pascals. Apparent respiration rate (CO(2) efflux in the dark) of expanded leaves was then measured at ambient CO(2) partial pressure of 5 to 95 pascals. Calculated intercellular CO(2) partial pressure was proportional to ambient CO(2) partial pressure in these short-term experiments. The CO(2) level strongly affected apparent respiration rate: a doubling of the partial pressure of CO(2) typically inhibited respiration by 25 to 30%, whereas a decrease in CO(2) elicited a corresponding increase in respiration. These responses were readily reversible. A flexible, sensitive regulatory interaction between CO(2) (a byproduct of respiration) and some component(s) of heterotrophic metabolism is indicated.
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Affiliation(s)
- J S Amthor
- Department of Agronomy and Range Science, University of California, Davis, California 95616
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Koch GW, Bloom AJ, Chapin FS. Ammonium and nitrate as nitrogen sources in two Eriophorum species. Oecologia 1991; 88:570-573. [DOI: 10.1007/bf00317721] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/1990] [Accepted: 07/30/1991] [Indexed: 11/25/2022]
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