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Luu H, Ris Lambers JH, Lutz JA, Metz M, Snell RS. The importance of regeneration processes on forest biodiversity in old-growth forests in the Pacific Northwest. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230016. [PMID: 38583471 PMCID: PMC10999264 DOI: 10.1098/rstb.2023.0016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 12/08/2023] [Indexed: 04/09/2024] Open
Abstract
Forest diversity is the outcome of multiple species-specific processes and tolerances, from regeneration, growth, competition and mortality of trees. Predicting diversity thus requires a comprehensive understanding of those processes. Regeneration processes have traditionally been overlooked, due to high stochasticity and assumptions that recruitment is not limiting for forests. Thus, we investigated the importance of seed production and seedling survival on forest diversity in the Pacific Northwest (PNW) using a forest gap model (ForClim). Equations for regeneration processes were fit to empirical data and added into the model, followed by simulations where regeneration processes and parameter values varied. Adding regeneration processes into ForClim improved the simulation of species composition, compared to Forest Inventory Analysis data. We also found that seed production was not as important as seedling survival, and the time it took for seedlings to grow into saplings was a critical recruitment parameter for accurately capturing tree species diversity in PNW forest stands. However, our simulations considered historical climate only. Due to the sensitivity of seed production and seedling survival to weather, future climate change may alter seed production or seedling survival and future climate change simulations should include these regeneration processes to predict future forest dynamics in the PNW. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.
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Affiliation(s)
- Hoang Luu
- Environmental and Plant Biology, Ohio University, Athens, OH 45701-2978, USA
| | | | - James A. Lutz
- Wildland Resources, Utah State University, Logan, UT 84322, USA
| | | | - Rebecca S. Snell
- Environmental and Plant Biology, Ohio University, Athens, OH 45701-2978, USA
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2
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Phillips ML, Lauria C, Spector T, Bradford JB, Gehring C, Osborne BB, Howell A, Grote EE, Rondeau RJ, Trimber GM, Robinson B, Reed SC. Trajectories and tipping points of piñon-juniper woodlands after fire and thinning. GLOBAL CHANGE BIOLOGY 2024; 30:e17149. [PMID: 38342970 DOI: 10.1111/gcb.17149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/29/2023] [Accepted: 12/04/2023] [Indexed: 02/13/2024]
Abstract
Piñon-juniper (PJ) woodlands are a dominant community type across the Intermountain West, comprising over a million acres and experiencing critical effects from increasing wildfire. Large PJ mortality and regeneration failure after catastrophic wildfire have elevated concerns about the long-term viability of PJ woodlands. Thinning is increasingly used to safeguard forests from fire and in an attempt to increase climate resilience. We have only a limited understanding of how fire and thinning will affect the structure and function of PJ ecosystems. Here, we examined vegetation structure, microclimate conditions, and PJ regeneration dynamics following ~20 years post-fire and thinning treatments. We found that burned areas had undergone a state shift that did not show signs of returning to their previous state. This shift was characterized by (1) distinct plant community composition dominated by grasses; (2) a lack of PJ recruitment; (3) a decrease in the sizes of interspaces in between plants; (4) lower abundance of late successional biological soil crusts; (5) lower mean and minimum daily soil moisture values; (6) lower minimum daily vapor pressure deficit; and (7) higher photosynthetically active radiation. Thinning created distinct plant communities and served as an intermediate between intact and burned communities. More intensive thinning decreased PJ recruitment and late successional biocrust cover. Our results indicate that fire has the potential to create drier and more stressful microsite conditions, and that, in the absence of active management following fire, there may be shifts to persistent ecological states dominated by grasses. Additionally, more intensive thinning had a larger impact on community structure and recruitment than less intensive thinning, suggesting that careful consideration of goals could help avoid unintended consequences. While our results indicate the vulnerability of PJ ecosystems to fire, they also highlight management actions that could be adapted to create conditions that promote PJ re-establishment.
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Affiliation(s)
- Michala L Phillips
- U.S. Geological Survey, Pacific Island Ecosystems Research Center, Hawai'i Volcanoes National Park, Hawai'i, USA
| | - Cara Lauria
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, USA
| | - Tova Spector
- U.S. Forest Service, Intermountain Region 4, Ogden, Utah, USA
| | - John B Bradford
- U.S. Geological Survey, Southwest Biological Science Center, Flagstaff, Arizona, USA
| | - Catherine Gehring
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Brooke B Osborne
- Department of Environment and Society, Utah State University, Moab, Utah, USA
| | - Armin Howell
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, USA
| | - Edmund E Grote
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, USA
| | - Renee J Rondeau
- Colorado State University, Colorado Natural Heritage Program, Hesperus, Colorado, USA
| | - Gillian M Trimber
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | | | - Sasha C Reed
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, USA
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3
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Vasey GL, Urza AK, Chambers JC, Pringle EG, Weisberg PJ. Clinal variations in seedling traits and responses to water availability correspond to seed-source environmental gradients in a foundational dryland tree species. ANNALS OF BOTANY 2023; 132:203-216. [PMID: 36905361 PMCID: PMC10583205 DOI: 10.1093/aob/mcad041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 03/10/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND AND AIMS In dryland ecosystems, conifer species are threatened by more frequent and severe droughts, which can push species beyond their physiological limits. Adequate seedling establishment will be critical for future resilience to global change. We used a common garden glasshouse experiment to determine how seedling functional trait expression and plasticity varied among seed sources in response to a gradient of water availability, focusing on a foundational dryland tree species of the western USA, Pinus monophylla. We hypothesized that the expression of growth-related seedling traits would show patterns consistent with local adaptation, given clinal variation among seed source environments. METHODS We collected P. monophylla seeds from 23 sites distributed across rangewide gradients of aridity and seasonal moisture availability. A total of 3320 seedlings were propagated with four watering treatments representing progressively decreasing water availability. Above- and below-ground growth-related traits of first-year seedlings were measured. Trait values and trait plasticity, here representing the degree of variation among watering treatments, were modelled as a function of watering treatment and environmental conditions at the seed source locations (i.e. water availability, precipitation seasonality). KEY RESULTS We found that, under all treatments, seedlings from more arid climates had larger above- and below-ground biomass compared to seedlings from sites experiencing lower growing-season water limitation, even after accounting for differences in seed size. Additionally, trait plasticity in response to watering treatments was greatest for seedlings from summer-wet sites that experience periodic monsoonal rain events. CONCLUSIONS Our results show that P. monophylla seedlings respond to drought through plasticity in multiple traits, but variation in trait responses suggests that different populations are likely to respond uniquely to changes in local climate. Such trait diversity will probably influence the potential for future seedling recruitment in woodlands that are projected to experience extensive drought-related tree mortality.
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Affiliation(s)
- Georgia L Vasey
- Department of Natural Resources and Environmental Science, University of Nevada Reno, 1664 N. Virginia Street, Mail Stop 186, Reno, NV 89557, USA
| | - Alexandra K Urza
- USDA Forest Service, Rocky Mountain Research Station, 920 Valley Road, Reno, NV 89512, USA
| | - Jeanne C Chambers
- USDA Forest Service, Rocky Mountain Research Station, 920 Valley Road, Reno, NV 89512, USA
| | - Elizabeth G Pringle
- Department of Biology, Program in Ecology, Evolution and Conservation Biology, University of Nevada Reno, 1664 N. Virginia Street, Mail Stop 0314, Reno, NV 89557, USA
| | - Peter J Weisberg
- Department of Natural Resources and Environmental Science, University of Nevada Reno, 1664 N. Virginia Street, Mail Stop 186, Reno, NV 89557, USA
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4
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The aboveground and belowground growth characteristics of juvenile conifers in the southwestern United States. Ecosphere 2021. [DOI: 10.1002/ecs2.3839] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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5
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Dimitri LA, Longland WS. Pilfering of western juniper seed caches by scatter-hoarding rodents varies by microsite and canopy type. Integr Zool 2021; 17:192-205. [PMID: 33433951 DOI: 10.1111/1749-4877.12517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Scatter-hoarding rodents store seeds throughout their home ranges in superficially buried caches which, unlike seeds larder-hoarded in burrows, are difficult to defend. Cached seeds are often pilfered by other scatter-hoarders and either re-cached, eaten or larder-hoarded. Such seed movements can influence seedling recruitment, because only seeds remaining in caches are likely to germinate. Although the importance of scatter-hoarding rodents in the dispersal of western juniper seeds has recently been revealed, the level of pilfering that occurs after initial burial is unknown. Seed traits, soil moisture, and substrate can influence pilfering processes, but less is known about how pilfering varies among caches placed in open versus canopy microsites, or how cache discovery and removal varies among different canopy-types, tree versus shrub. We compared the removal of artificial caches between open and canopy microsites and between tree and shrub canopies at two sites in northeastern California during late spring and fall. We also used trail cameras at one site to monitor artificial cache removal, identify potential pilferers, and illuminate microsite use by scatter-hoarders. Removal of artificial caches was faster in open microsites at both sites during both seasons, and more caches were removed from shrub than tree canopies. California kangaroo rats were the species observed most on cameras, foraging most often in open microsites, which could explain the observed pilfering patterns. This is the first study to document pilfering of western juniper seeds, providing further evidence of the importance of scatter-hoarding rodent foraging behavior in understanding seedling recruitment processes in juniper woodlands.
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Affiliation(s)
- Lindsay A Dimitri
- Agricultural Research Service, Great Basin Rangeland Research, USDA, USA
| | - William S Longland
- Agricultural Research Service, Great Basin Rangeland Research, USDA, USA
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Huang L, Zhou L, Wang J, Jin C, Hu S, Qian S, Lin D, Zhao L, Yang Y. Short-term decline of Castanopsis fargesii adult trees promotes conspecific seedling regeneration: The complete process from seed production to seedling establishment. Ecol Evol 2020; 10:10657-10671. [PMID: 33072287 PMCID: PMC7548161 DOI: 10.1002/ece3.6719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 11/05/2022] Open
Abstract
Declining forests usually face uncertain regeneration dynamics and recovery trajectories, which are challenging to forest management. In this study, we investigated the decline pattern of Castanopsis fargesii and examined the effects on conspecific seedling regeneration. We found that 61.45% of adult individuals were in decline and the smaller DBH size classes of trees (10–40 cm) had a greater probability of decline. Most of the intermediate decline (94.52%) and nondecline individuals (95.23%) did not worsen, and the crowns of 21.91% of the intermediate decline trees were recovered during 2013–2018. Adult tree decline had a negative effect on seed production (mean mature seed density of nondecline, intermediate decline, and high decline individuals was 167.3, 63.3, and 2.1 seeds/m2, respectively), but no effect on key seed traits. The seed survival rate of declining trees was greater than that of nondeclining trees at both the seed production and seed dispersal stages. The seed to seedling transition rates in canopy gaps, decline habitats, and nondecline habitats were 7.94%, 9.47%, and 109.24%, respectively. The survival rate and height growth of newly germinated seedlings were positively correlated with the light condition, which was notably accelerated in the canopy gaps. Taken together, these results indicate that the reduction in seed production of some adult trees had a weakly negative effect on new seedling recruitment, while the improved environmental condition after the decline significantly enhanced the survival and growth of both advanced and new germinated seedlings. Looking at the overall life history, the short‐term defoliation and mortality of some C. fargesii adult trees can be regarded as a natural forest disturbance that favors conspecific seedling regeneration. High‐intensity management measures would be unnecessary in cases of an emerging intermediate decline in this forest.
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Affiliation(s)
- Li Huang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China
| | - Lihua Zhou
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China
| | - Jingmei Wang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China
| | - Cheng Jin
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China
| | - Siwei Hu
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China
| | - Shenhua Qian
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China
| | - Dunmei Lin
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China
| | - Liang Zhao
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China
| | - Yongchuan Yang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing China.,Joint International Research Laboratory of Green Building and Built Environment Ministry of Education Chongqing University Chongqing China
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7
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Andrus RA, Harvey BJ, Hoffman A, Veblen TT. Reproductive maturity and cone abundance vary with tree size and stand basal area for two widely distributed conifers. Ecosphere 2020. [DOI: 10.1002/ecs2.3092] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Robert A. Andrus
- Department of Geography University of Colorado Boulder Boulder Colorado 80309 USA
| | - Brian J. Harvey
- School of Environmental and Forest Sciences University of Washington Seattle Washington 98195 USA
| | - Ashley Hoffman
- Department of Geography University of Colorado Boulder Boulder Colorado 80309 USA
| | - Thomas T. Veblen
- Department of Geography University of Colorado Boulder Boulder Colorado 80309 USA
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8
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Young DJN, Meyer M, Estes B, Gross S, Wuenschel A, Restaino C, Safford HD. Forest recovery following extreme drought in California, USA: natural patterns and effects of pre-drought management. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02002. [PMID: 31519065 DOI: 10.1002/eap.2002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 06/14/2019] [Accepted: 07/17/2019] [Indexed: 06/10/2023]
Abstract
Rising temperatures and more frequent and severe droughts are driving increases in tree mortality in forests around the globe. However, in many cases, the likely trajectories of forest recovery following drought-related mortality are poorly understood. In many fire-suppressed western U.S. forests, management is applied to reverse densification and restore natural forest structure and species composition, but it is unclear how such management affects post-mortality recovery. We addressed these uncertainties by examining forest stands that experienced mortality during the severe drought of 2012-2016 in California, USA. We surveyed post-drought vegetation along a gradient of overstory mortality severity in paired treated (mechanically thinned or prescribed-burned) and untreated areas in the Sierra Nevada. Treatment substantially reduced tree density, particularly in smaller tree size classes, and these effects persisted through severe drought-related overstory mortality. However, even in treated areas with severe mortality (>67% basal area mortality), the combined density of residual (surviving) trees (mean 44 trees/ha) and saplings (mean 189 saplings/ha) frequently (86% of plots) fell within or exceeded the natural range of variation (NRV) of tree density, suggesting little need for reforestation intervention to increase density. Residual tree densities in untreated high-mortality plots were significantly higher (mean 192 trees/ha and 506 saplings/ha), and 96% of these plots met or exceeded the NRV. Treatment disproportionately removed shade-tolerant conifer species, while mortality in the drought event was concentrated in pines (Pinus ponderosa and P. lambertiana); as a consequence, the residual trees, saplings, and seedlings in treated areas, particularly those that had experienced moderate or high drought-related mortality, were more heavily dominated by broadleaf ("hardwood") trees (particularly Quercus kelloggii and Q. chrysolepis). In contrast, residual trees and regeneration in untreated stands were heavily dominated by shade-tolerant conifer species (Abies concolor and Calocedrus decurrens), suggesting a need for future treatment. Because increased dominance of hardwoods brings benefits for plant and animal diversity and stand resilience, the ecological advantages of mechanical thinning and prescribed fire treatments may, depending on the management perspective, extend even to stands that ultimately experience high drought-related mortality following treatment.
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Affiliation(s)
- Derek J N Young
- Department of Environmental Science and Policy, University of California, Davis, Davis, California, 95616, USA
| | - Marc Meyer
- USDA Forest Service, Pacific Southwest Region, Southern Sierra Province, Bishop, California, 93514, USA
| | - Becky Estes
- USDA Forest Service, Pacific Southwest Region, Central Sierra Province, Placerville, California, 95667, USA
| | - Shana Gross
- USDA Forest Service, Pacific Southwest Region, Central Sierra Province, South Lake Tahoe, California, 96150, USA
| | - Amarina Wuenschel
- USDA Forest Service, Pacific Southwest Region, Southern Sierra Province, Clovis, California, 93611, USA
| | - Christina Restaino
- Department of Environmental Science and Policy, University of California, Davis, Davis, California, 95616, USA
| | - Hugh D Safford
- Department of Environmental Science and Policy, University of California, Davis, Davis, California, 95616, USA
- USDA Forest Service, Pacific Southwest Region, Vallejo, California, 94592, USA
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9
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Mueller RC, Scudder CM, Whitham TG, Gehring CA. Legacy effects of tree mortality mediated by ectomycorrhizal fungal communities. THE NEW PHYTOLOGIST 2019; 224:155-165. [PMID: 31209891 DOI: 10.1111/nph.15993] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 05/31/2019] [Indexed: 05/16/2023]
Abstract
Successive droughts have resulted in extensive tree mortality in the southwestern United States. Recovery of these areas is dependent on the survival and recruitment of young trees. For trees that rely on ectomycorrhizal fungi (EMF) for survival and growth, changes in soil fungal communities following tree mortality could negatively affect seedling establishment. We used tree-focused and stand-scale measurements to examine the impact of pinyon pine mortality on the performance of surviving juvenile trees and the potential for mutualism limitation of seedling establishment via altered EMF communities. Mature pinyon mortality did not affect the survival of juvenile pinyons, but increased their growth. At both tree and stand scales, high pinyon mortality had no effect on the abundance of EMF inocula, but led to altered EMF community composition including increased abundance of Geopora and reduced abundance of Tuber. Seedling biomass was strongly positively associated with Tuber abundance, suggesting that reductions in this genus with pinyon mortality could have negative consequences for establishing seedlings. These findings suggest that whereas mature pinyon mortality led to competitive release for established juvenile pinyons, changes in EMF community composition with mortality could limit successful seedling establishment and growth in high-mortality sites.
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Affiliation(s)
- Rebecca C Mueller
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, 617 S. Beaver Street, Flagstaff, AZ, 86011, USA
- Chemical and Biological Engineering Department, Montana State University, Bozeman, MT, 59717, USA
| | - Crescent M Scudder
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, 617 S. Beaver Street, Flagstaff, AZ, 86011, USA
| | - Thomas G Whitham
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, 617 S. Beaver Street, Flagstaff, AZ, 86011, USA
| | - Catherine A Gehring
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, 617 S. Beaver Street, Flagstaff, AZ, 86011, USA
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10
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Urza AK, Weisberg PJ, Chambers JC, Sullivan BW. Shrub facilitation of tree establishment varies with ontogenetic stage across environmental gradients. THE NEW PHYTOLOGIST 2019; 223:1795-1808. [PMID: 31125432 DOI: 10.1111/nph.15957] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 05/19/2019] [Indexed: 06/09/2023]
Abstract
Plant-plant interactions are important drivers of ecosystem structure and function, yet predicting interaction outcomes across environmental gradients remains challenging. Understanding how interactions are affected by ontogenetic shifts in plant characteristics can provide insight into the drivers of interactions and improve our ability to anticipate ecosystem responses to environmental change. We developed a conceptual framework of nurse shrub facilitation of tree establishment. We used a combination of field experiments and environmental measurements to test the framework with a shrub (Artemisia tridentata) and a tree (Pinus monophylla), two foundation species in a semiarid environment. Shrub microsites allowed trees to overcome an early population bottleneck and successfully establish in areas without tree cover. Shrubs facilitated trees at multiple ontogenetic stages, but the net outcome of the interaction shifted from strongly positive to neutral after the transition of P. monophylla from juvenile to adult foliage. Microhabitat conditions varied across a broad elevational gradient, but interaction outcomes were not strongly related to elevation. Favorable microsites provided by A. tridentata cover are crucial for P. monophylla recovery after stand-replacing disturbance. Models of vegetation response to rapid global environmental change should incorporate the critically important role of nurse shrub interactions for ameliorating population bottlenecks in tree establishment.
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Affiliation(s)
- Alexandra K Urza
- USDA Forest Service, Rocky Mountain Research Station, 920 Valley Rd, Reno, NV, 89512, USA
- Program in Ecology, Evolution and Conservation Biology, University of Nevada-Reno, 1664 N. Virginia St., Reno, NV, 89557, USA
| | - Peter J Weisberg
- Program in Ecology, Evolution and Conservation Biology, University of Nevada-Reno, 1664 N. Virginia St., Reno, NV, 89557, USA
- Department of Natural Resources and Environmental Science, University of Nevada-Reno, 1664 N. Virginia St., Reno, NV, 89557, USA
| | - Jeanne C Chambers
- USDA Forest Service, Rocky Mountain Research Station, 920 Valley Rd, Reno, NV, 89512, USA
- Program in Ecology, Evolution and Conservation Biology, University of Nevada-Reno, 1664 N. Virginia St., Reno, NV, 89557, USA
| | - Benjamin W Sullivan
- Program in Ecology, Evolution and Conservation Biology, University of Nevada-Reno, 1664 N. Virginia St., Reno, NV, 89557, USA
- Department of Natural Resources and Environmental Science, University of Nevada-Reno, 1664 N. Virginia St., Reno, NV, 89557, USA
- Global Water Center, University of Nevada-Reno, 1664 N. Virginia St, Reno, NV, 89557, USA
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Whipple AV, Cobb NS, Gehring CA, Mopper S, Flores-Rentería L, Whitham TG. Long-Term Studies Reveal Differential Responses to Climate Change for Trees Under Soil- or Herbivore-Related Stress. FRONTIERS IN PLANT SCIENCE 2019; 10:132. [PMID: 30833952 PMCID: PMC6387935 DOI: 10.3389/fpls.2019.00132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 01/25/2019] [Indexed: 06/09/2023]
Abstract
Worldwide, trees are confronting increased temperature and aridity, exacerbating susceptibility to herbivory. Long-term studies comparing patterns of plant performance through drought can help identify variation among and within populations in vulnerability to climate change and herbivory. We use long-term monitoring data to examine our overarching hypothesis that the negative impacts of poor soil and herbivore susceptibility would be compounded by severe drought. We studied pinyon pine, Pinus edulis, a widespread southwestern tree species that has suffered extensive climate-change related mortality. We analyzed data on mortality, growth, male reproduction, and herbivory collected for 14-32 years in three areas with distinct soil-types. We used standardized precipitation-evapotranspiration index (SPEI) as a climate proxy that summarizes the impacts of drought due to precipitation and temperature variation on semi-arid forests. Several key findings emerged: (1) Plant performance measurements did not support our hypothesis that trees growing in stressful, coarse-textured soils would suffer more than trees growing in finer-textured soils. Stem growth at the area with coarse, young cinder soils (area one) responded only weakly to drought, while stem growth on more developed soils with sedimentary (area two) and volcanic (area three) substrates, was strongly negatively affected by drought. Male reproduction declined less with drought at area one and more at areas two and three. Overall mortality was 30% on coarse cinder soils (area one) and averaged 55% on finer soil types (areas two and three). (2) Although moth herbivore susceptible trees were hypothesized to suffer more with drought than moth resistant trees, the opposite occurred. Annual stem growth was negatively affected by drought for moth resistant trees, but much less strongly for moth susceptible trees. (3) In contrast to our hypothesis, moths declined with drought. Overall, chronically water-stressed and herbivore-susceptible trees had smaller declines in performance relative to less-stressed trees during drought years. These long-term findings support the idea that stressed trees might be more resistant to drought since they may have adapted or acclimated to resist drought-related mortality.
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Affiliation(s)
- Amy V. Whipple
- Department of Biological Sciences, Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Neil S. Cobb
- Department of Biological Sciences, Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Catherine A. Gehring
- Department of Biological Sciences, Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Susan Mopper
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, United States
| | | | - Thomas G. Whitham
- Department of Biological Sciences, Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
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12
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Copeland SM, Bradford JB, Duniway MC, Butterfield BJ. Life history characteristics may be as important as climate projections for defining range shifts: An example for common tree species in the intermountain western US. DIVERS DISTRIB 2018. [DOI: 10.1111/ddi.12813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Stella M. Copeland
- Merriam-Powell Center for Environmental Research and Department of Biological Sciences; Northern Arizona University; Flagstaff Arizona
- U.S. Geological Survey, Southwest Biological Science Center; Flagstaff Arizona
| | - John B. Bradford
- U.S. Geological Survey, Southwest Biological Science Center; Flagstaff Arizona
| | | | - Bradley J. Butterfield
- Merriam-Powell Center for Environmental Research and Department of Biological Sciences; Northern Arizona University; Flagstaff Arizona
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13
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Flores-Rentería L, Whipple AV, Benally GJ, Patterson A, Canyon B, Gehring CA. Higher Temperature at Lower Elevation Sites Fails to Promote Acclimation or Adaptation to Heat Stress During Pollen Germination. FRONTIERS IN PLANT SCIENCE 2018; 9:536. [PMID: 29760715 PMCID: PMC5936790 DOI: 10.3389/fpls.2018.00536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 04/06/2018] [Indexed: 05/27/2023]
Abstract
High temperatures associated with climate change are expected to be detrimental for aspects of plant reproduction, such as pollen viability. We hypothesized that (1) higher peak temperatures predicted with climate change would have a minimal effect on pollen viability, while high temperatures during pollen germination would negatively affect pollen viability, (2) high temperatures during pollen dispersal would facilitate acclimation to high temperatures during pollen germination, and (3) pollen from populations at sites with warmer average temperatures would be better adapted to high temperature peaks. We tested these hypotheses in Pinus edulis, a species with demonstrated sensitivity to climate change, using populations along an elevational gradient. We tested for acclimation to high temperatures by measuring pollen viability during dispersal and germination stages in pollen subjected to 30, 35, and 40°C in a factorial design. We also characterized pollen phenology and measured pollen heat tolerance using trees from nine sites along a 200 m elevational gradient that varied 4°C in temperature. We demonstrated that this gradient is biologically meaningful by evaluating variation in vegetation composition and P. edulis performance. Male reproduction was negatively affected by high temperatures, with stronger effects during pollen germination than pollen dispersal. Populations along the elevational gradient varied in pollen phenology, vegetation composition, plant water stress, nutrient availability, and plant growth. In contrast to our hypothesis, pollen viability was highest in pinyons from mid-elevation sites rather than from lower elevation sites. We found no evidence of acclimation or adaptation of pollen to high temperatures. Maximal plant performance as measured by growth did not occur at the same elevation as maximal pollen viability. These results indicate that periods of high temperature negatively affected sexual reproduction, such that even high pollen production may not result in successful fertilization due to low germination. Acquired thermotolerance might not limit these impacts, but pinyon could avoid heat stress by phenological adjustment of pollen development. Higher pollen viability at the core of the distribution could be explained by an optimal combination of biotic and abiotic environmental factors. The disconnect between measures of growth and pollen production suggests that vigor metrics may not accurately estimate reproduction.
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Affiliation(s)
| | - Amy V. Whipple
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Gilbert J. Benally
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Adair Patterson
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Brandon Canyon
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Catherine A. Gehring
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
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Flores-Rentería L, Whipple AV, Benally GJ, Patterson A, Canyon B, Gehring CA. Higher Temperature at Lower Elevation Sites Fails to Promote Acclimation or Adaptation to Heat Stress During Pollen Germination. FRONTIERS IN PLANT SCIENCE 2018. [PMID: 29760715 DOI: 10.3389/fpls.2018.00536/full] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
High temperatures associated with climate change are expected to be detrimental for aspects of plant reproduction, such as pollen viability. We hypothesized that (1) higher peak temperatures predicted with climate change would have a minimal effect on pollen viability, while high temperatures during pollen germination would negatively affect pollen viability, (2) high temperatures during pollen dispersal would facilitate acclimation to high temperatures during pollen germination, and (3) pollen from populations at sites with warmer average temperatures would be better adapted to high temperature peaks. We tested these hypotheses in Pinus edulis, a species with demonstrated sensitivity to climate change, using populations along an elevational gradient. We tested for acclimation to high temperatures by measuring pollen viability during dispersal and germination stages in pollen subjected to 30, 35, and 40°C in a factorial design. We also characterized pollen phenology and measured pollen heat tolerance using trees from nine sites along a 200 m elevational gradient that varied 4°C in temperature. We demonstrated that this gradient is biologically meaningful by evaluating variation in vegetation composition and P. edulis performance. Male reproduction was negatively affected by high temperatures, with stronger effects during pollen germination than pollen dispersal. Populations along the elevational gradient varied in pollen phenology, vegetation composition, plant water stress, nutrient availability, and plant growth. In contrast to our hypothesis, pollen viability was highest in pinyons from mid-elevation sites rather than from lower elevation sites. We found no evidence of acclimation or adaptation of pollen to high temperatures. Maximal plant performance as measured by growth did not occur at the same elevation as maximal pollen viability. These results indicate that periods of high temperature negatively affected sexual reproduction, such that even high pollen production may not result in successful fertilization due to low germination. Acquired thermotolerance might not limit these impacts, but pinyon could avoid heat stress by phenological adjustment of pollen development. Higher pollen viability at the core of the distribution could be explained by an optimal combination of biotic and abiotic environmental factors. The disconnect between measures of growth and pollen production suggests that vigor metrics may not accurately estimate reproduction.
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Affiliation(s)
| | - Amy V Whipple
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Gilbert J Benally
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Adair Patterson
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Brandon Canyon
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
| | - Catherine A Gehring
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, United States
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15
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Cone and seed traits of two Juniperus species influence roles of frugivores and scatter-hoarding rodents as seed dispersal agents. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2017. [DOI: 10.1016/j.actao.2017.09.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Dimitri LA, Longland WS. Distribution of Western Juniper Seeds Across an Ecotone and Implications for Dispersal. WEST N AM NATURALIST 2017. [DOI: 10.3398/064.077.0209] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Lindsay A. Dimitri
- USDA, Agricultural Research Service, Great Basin Rangelands Research Unit, 920 Valley Road, Reno, NV 89512
| | - William S. Longland
- USDA, Agricultural Research Service, Great Basin Rangelands Research Unit, 920 Valley Road, Reno, NV 89512
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17
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Redmond MD, Kelsey KC, Urza AK, Barger NN. Interacting effects of climate and landscape physiography on piñon pine growth using an individual‐based approach. Ecosphere 2017. [DOI: 10.1002/ecs2.1681] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Miranda D. Redmond
- Department of Forest and Rangeland Stewardship Colorado State University 1472 Campus Delivery Fort Collins Colorado 80523 USA
- Ecology and Evolutionary Biology Department University of Colorado Boulder Campus Box 334, 2200 Colorado Avenue Boulder Colorado 80309 USA
| | - Katharine C. Kelsey
- Environmental Studies Program University of Colorado Boulder Campus Box 399, 2200 Colorado Avenue Boulder Colorado 80309 USA
| | - Alexandra K. Urza
- Department of Natural Resources and Environmental Science Program in Ecology, Evolution and Conservation Biology University of Nevada Reno Nevada 89557 USA
| | - Nichole N. Barger
- Ecology and Evolutionary Biology Department University of Colorado Boulder Campus Box 334, 2200 Colorado Avenue Boulder Colorado 80309 USA
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18
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Molowny-Horas R, Suarez ML, Lloret F. Changes in the natural dynamics of Nothofagus dombeyi
forests: population modeling with increasing drought frequencies. Ecosphere 2017. [DOI: 10.1002/ecs2.1708] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
| | - Maria Laura Suarez
- Laboratorio Ecotono; INIBIOMA; CONICET; Universidad Nacional del Comahue; Quintral 1250 8400 Bariloche Argentina
| | - Francisco Lloret
- CREAF; Cerdanyola del Vallès 08193 Spain
- Univ Autònoma Barcelona; Cerdanyola del Vallès 08193 Spain
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19
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Ibáñez B, Gómez-Aparicio L, Ávila JM, Pérez-Ramos IM, Marañón T. Effects of Quercus suber Decline on Woody Plant Regeneration: Potential Implications for Successional Dynamics in Mediterranean Forests. Ecosystems 2016. [DOI: 10.1007/s10021-016-0044-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Clark JS, Iverson L, Woodall CW, Allen CD, Bell DM, Bragg DC, D'Amato AW, Davis FW, Hersh MH, Ibanez I, Jackson ST, Matthews S, Pederson N, Peters M, Schwartz MW, Waring KM, Zimmermann NE. The impacts of increasing drought on forest dynamics, structure, and biodiversity in the United States. GLOBAL CHANGE BIOLOGY 2016; 22:2329-2352. [PMID: 26898361 DOI: 10.1111/gcb.13160] [Citation(s) in RCA: 162] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 10/02/2015] [Accepted: 10/05/2015] [Indexed: 06/05/2023]
Abstract
We synthesize insights from current understanding of drought impacts at stand-to-biogeographic scales, including management options, and we identify challenges to be addressed with new research. Large stand-level shifts underway in western forests already are showing the importance of interactions involving drought, insects, and fire. Diebacks, changes in composition and structure, and shifting range limits are widely observed. In the eastern US, the effects of increasing drought are becoming better understood at the level of individual trees, but this knowledge cannot yet be confidently translated to predictions of changing structure and diversity of forest stands. While eastern forests have not experienced the types of changes seen in western forests in recent decades, they too are vulnerable to drought and could experience significant changes with increased severity, frequency, or duration in drought. Throughout the continental United States, the combination of projected large climate-induced shifts in suitable habitat from modeling studies and limited potential for the rapid migration of tree populations suggests that changing tree and forest biogeography could substantially lag habitat shifts already underway. Forest management practices can partially ameliorate drought impacts through reductions in stand density, selection of drought-tolerant species and genotypes, artificial regeneration, and the development of multistructured stands. However, silvicultural treatments also could exacerbate drought impacts unless implemented with careful attention to site and stand characteristics. Gaps in our understanding should motivate new research on the effects of interactions involving climate and other species at the stand scale and how interactions and multiple responses are represented in models. This assessment indicates that, without a stronger empirical basis for drought impacts at the stand scale, more complex models may provide limited guidance.
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Affiliation(s)
- James S Clark
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
| | - Louis Iverson
- Forest Service, Northern Research Station, 359 Main Road, Delaware, OH, 43015, USA
| | | | - Craig D Allen
- U.S. Geological Survey, Fort Collins Science Center, Jemez Mountains Field Station, Los Alamos, NM, 87544, USA
| | - David M Bell
- Forest Service, Pacific Northwest Research Station, Corvallis, OR, 97331, USA
| | - Don C Bragg
- Forest Service, Southern Research Station, Monticello, AR, 71656, USA
| | - Anthony W D'Amato
- Rubenstein School of Environment and Natural Resources, University of Vermont, 04E Aiken Center, 81 Carrigan Dr., Burlington, VT, 05405, USA
| | - Frank W Davis
- Bren School of Environmental Science and Management, University of California, Santa Barbara, CA, 93106, USA
| | - Michelle H Hersh
- Department of Biology, Sarah Lawrence College, New York, NY, 10708, USA
| | - Ines Ibanez
- School of Natural Resources and Environment, University of Michigan, 2546 Dana Building, Ann Arbor, MI, 48109, USA
| | - Stephen T Jackson
- U.S. Geological Survey, Southwest Climate Science Center and Department of Geosciences, University of Arizona, 1064 E. Lowell St., PO Box 210137, Tucson, AZ, 85721, USA
| | - Stephen Matthews
- School of Environment and Natural Resources, Ohio State University, Columbus, OH, 43210, USA
| | | | - Matthew Peters
- Forest Service, Northern Research Station, Delaware, OH, 43015, USA
| | - Mark W Schwartz
- Department of Environmental Science and Policy, UC Davis, Davis, CA, 93106, USA
| | - Kristen M Waring
- School of Forestry, Northern Arizona University, Flagstaff, AZ, 86001, USA
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21
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Mitchell PJ, O'Grady AP, Pinkard EA, Brodribb TJ, Arndt SK, Blackman CJ, Duursma RA, Fensham RJ, Hilbert DW, Nitschke CR, Norris J, Roxburgh SH, Ruthrof KX, Tissue DT. An ecoclimatic framework for evaluating the resilience of vegetation to water deficit. GLOBAL CHANGE BIOLOGY 2016; 22:1677-1689. [PMID: 26643922 DOI: 10.1111/gcb.13177] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 11/18/2015] [Indexed: 06/05/2023]
Abstract
The surge in global efforts to understand the causes and consequences of drought on forest ecosystems has tended to focus on specific impacts such as mortality. We propose an ecoclimatic framework that takes a broader view of the ecological relevance of water deficits, linking elements of exposure and resilience to cumulative impacts on a range of ecosystem processes. This ecoclimatic framework is underpinned by two hypotheses: (i) exposure to water deficit can be represented probabilistically and used to estimate exposure thresholds across different vegetation types or ecosystems; and (ii) the cumulative impact of a series of water deficit events is defined by attributes governing the resistance and recovery of the affected processes. We present case studies comprising Pinus edulis and Eucalyptus globulus, tree species with contrasting ecological strategies, which demonstrate how links between exposure and resilience can be examined within our proposed framework. These examples reveal how climatic thresholds can be defined along a continuum of vegetation functional responses to water deficit regimes. The strength of this framework lies in identifying climatic thresholds on vegetation function in the absence of more complete mechanistic understanding, thereby guiding the formulation, application and benchmarking of more detailed modelling.
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Affiliation(s)
| | - Anthony P O'Grady
- CSIRO Land and Water, 15 College Rd, Sandy Bay, TAS, 7005, Australia
| | | | - Timothy J Brodribb
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7005, Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC, 3121, Australia
| | - Chris J Blackman
- Hawkesbury Institute for the Environment, Western Sydney University, Science Rd, Richmond, NSW, 2753, Australia
| | - Remko A Duursma
- Hawkesbury Institute for the Environment, Western Sydney University, Science Rd, Richmond, NSW, 2753, Australia
| | - Rod J Fensham
- Queensland Herbarium, Environmental Protection Agency, Mount Coot-tha Road, Toowong, QLD, 4066, Australia
- School of Biological Sciences, University of Queensland, Chancellors Pl., St Lucia, QLD, 4072, Australia
| | - David W Hilbert
- CSIRO Ecosystem Sciences, Tropical Forest Research Centre, Atherton, QLD, 4883, Australia
| | - Craig R Nitschke
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC, 3121, Australia
| | - Jaymie Norris
- Department of Environment, Land, Water and Planning, Victorian Government, Melbourne, VIC, 3000, Australia
| | - Stephen H Roxburgh
- CSIRO Land and Water, Clunies Ross St, Black Mountain, ACT, 2601, Australia
| | - Katinka X Ruthrof
- Centre of Excellence for Climate Change, Woodland and Forest Health, School of Veterinary and Life Sciences Murdoch University, 90 South St, Murdoch, WA, 6150, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Science Rd, Richmond, NSW, 2753, Australia
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22
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Redmond MD, Cobb NS, Clifford MJ, Barger NN. Woodland recovery following drought-induced tree mortality across an environmental stress gradient. GLOBAL CHANGE BIOLOGY 2015; 21:3685-95. [PMID: 26089027 DOI: 10.1111/gcb.12976] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 04/28/2015] [Indexed: 05/26/2023]
Abstract
Recent droughts and increasing temperatures have resulted in extensive tree mortality across the globe. Understanding the environmental controls on tree regeneration following these drought events will allow for better predictions of how these ecosystems may shift under a warmer, drier climate. Within the widely distributed piñon-juniper woodlands of the southwestern USA, a multiyear drought in 2002-2004 resulted in extensive adult piñon mortality and shifted adult woodland composition to a juniper-dominated, more savannah-type ecosystem. Here, we used pre- (1998-2001) and 10-year post- (2014) drought stand structure data of individually mapped trees at 42 sites to assess the effects of this drought on tree regeneration across a gradient of environmental stress. We found declines in piñon juvenile densities since the multiyear drought due to limited new recruitment and high (>50%) juvenile mortality. This is in contrast to juniper juvenile densities, which increased over this time period. Across the landscape, piñon recruitment was positively associated with live adult piñon densities and soil available water capacity, likely due to their respective effects on seed and water availability. Juvenile piñon survival was strongly facilitated by certain types of nurse trees and shrubs. These nurse plants also moderated the effects of environmental stress on piñon survival: Survival of interspace piñon juveniles was positively associated with soil available water capacity, whereas survival of nursed piñon juveniles was negatively associated with perennial grass cover. Thus, nurse plants had a greater facilitative effect on survival at sites with higher soil available water capacity and perennial grass cover. Notably, mean annual climatic water deficit and elevation were not associated with piñon recruitment or survival across the landscape. Our findings reveal a clear shift in successional trajectories toward a more juniper-dominated woodland and highlight the importance of incorporating biotic interactions and soil properties into species distribution modeling approaches.
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Affiliation(s)
- Miranda D Redmond
- Ecology and Evolutionary Biology Department, University of Colorado, Boulder, CO, 80302, USA
| | - Neil S Cobb
- Merriam Powel Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Michael J Clifford
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Las Vegas, NV, 89119, USA
| | - Nichole N Barger
- Ecology and Evolutionary Biology Department, University of Colorado, Boulder, CO, 80302, USA
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23
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Ibáñez B, Gómez-Aparicio L, Stoll P, Ávila JM, Pérez-Ramos IM, Marañón T. A neighborhood analysis of the consequences of Quercus suber decline for regeneration dynamics in Mediterranean forests. PLoS One 2015; 10:e0117827. [PMID: 25706723 PMCID: PMC4338116 DOI: 10.1371/journal.pone.0117827] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 12/31/2014] [Indexed: 11/22/2022] Open
Abstract
In forests, the vulnerable seedling stage is largely influenced by the canopy, which modifies the surrounding environment. Consequently, any alteration in the characteristics of the canopy, such as those promoted by forest dieback, might impact regeneration dynamics. Our work analyzes the interaction between canopy neighbors and seedlings in Mediterranean forests affected by the decline of their dominant species (Quercus suber). Our objective was to understand how the impacts of neighbor trees and shrubs on recruitment could affect future dynamics of these declining forests. Seeds of the three dominant tree species (Quercus suber, Olea europaea and Quercus canariensis) were sown in six sites during two consecutive years. Using a spatially-explicit, neighborhood approach we developed models that explained the observed spatial variation in seedling emergence, survival, growth and photochemical efficiency as a function of the size, identity, health, abundance and distribution of adult trees and shrubs in the neighborhood. We found strong neighborhood effects for all the performance estimators, particularly seedling emergence and survival. Tree neighbors positively affected emergence, independently of species identity or health. Alternatively, seedling survival was much lower in neighborhoods dominated by defoliated and dead Q. suber trees than in neighborhoods dominated by healthy trees. For the two oak species, these negative effects were consistent over the three years of the experimental seedlings. These results indicate that ongoing changes in species' relative abundance and canopy trees' health might alter the successional trajectories of Mediterranean oak-forests through neighbor-specific impacts on seedlings. The recruitment failure of dominant late-successional oaks in the gaps opened after Q. suber death would indirectly favor the establishment of other coexisting woody species, such as drought-tolerant shrubs. This could lead current forests to shift into open systems with lower tree cover. Adult canopy decline would therefore represent an additional factor threatening the recruitment of Quercus forests worldwide.
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Affiliation(s)
- Beatriz Ibáñez
- Instituto de Recursos Naturales y Agrobiología (IRNAS, CSIC), PO Box 1052, Sevilla 41080, Spain
| | - Lorena Gómez-Aparicio
- Instituto de Recursos Naturales y Agrobiología (IRNAS, CSIC), PO Box 1052, Sevilla 41080, Spain
| | - Peter Stoll
- Institute for Environmental Sciences, Section Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, CH-4056 Basel, Switzerland
| | - José M. Ávila
- Instituto de Recursos Naturales y Agrobiología (IRNAS, CSIC), PO Box 1052, Sevilla 41080, Spain
| | - Ignacio M. Pérez-Ramos
- Instituto de Recursos Naturales y Agrobiología (IRNAS, CSIC), PO Box 1052, Sevilla 41080, Spain
| | - Teodoro Marañón
- Instituto de Recursos Naturales y Agrobiología (IRNAS, CSIC), PO Box 1052, Sevilla 41080, Spain
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24
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Clifford MJ, Royer PD, Cobb NS, Breshears DD, Ford PL. Precipitation thresholds and drought-induced tree die-off: insights from patterns of Pinus edulis mortality along an environmental stress gradient. THE NEW PHYTOLOGIST 2013; 200:413-421. [PMID: 23772860 DOI: 10.1111/nph.12362] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 05/15/2013] [Indexed: 06/02/2023]
Abstract
Recent regional tree die-off events appear to have been triggered by a combination of drought and heat - referred to as 'global-change-type drought'. To complement experiments focused on resolving mechanisms of drought-induced tree mortality, an evaluation of how patterns of tree die-off relate to highly spatially variable precipitation is needed. Here, we explore precipitation relationships with a die-off event of pinyon pine (Pinus edulis Engelm.) in southwestern North America during the 2002-2003 global-change-type drought. Pinyon die-off and its relationship with precipitation was quantified spatially along a precipitation gradient in north-central New Mexico with standard field plot measurements of die-off combined with canopy cover derived from normalized burn ratio (NBR) from Landsat imagery. Pinyon die-off patterns revealed threshold responses to precipitation (cumulative 2002-2003) and vapor pressure deficit (VPD), with little to no mortality (< 10%) above 600 mm and below warm season VPD of c. 1.7 kPa. [Correction added after online publication 17 June 2013; in the preceding sentence, the word 'below' has been inserted.] Our results refine how precipitation patterns within a region influence pinyon die-off, revealing a precipitation and VPD threshold for tree mortality and its uncertainty band where other factors probably come into play - a response type that influences stand demography and landscape heterogeneity and is of general interest, yet has not been documented.
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Affiliation(s)
- Michael J Clifford
- Earth and Environmental Science Department, Lehigh University, Bethlehem, PA, 18015, USA
| | - Patrick D Royer
- Columbia Basin Groundwater Management Area, Kennewick, WA, 99366, USA
- Intera Geoscience and Engineering, Richland, WA, 99354, USA
| | - Neil S Cobb
- Merriam-Powell Center for Environmental Research, Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - David D Breshears
- Department of Ecology & Evolutionary Biology, School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, 85721, USA
| | - Paulette L Ford
- USDA Forest Service Rocky Mountain Research Station, Albuquerque, NM, 87102, USA
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25
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McDowell NG, Ryan MG, Zeppel MJB, Tissue DT. Feature: Improving our knowledge of drought-induced forest mortality through experiments, observations, and modeling. THE NEW PHYTOLOGIST 2013; 200:289-293. [PMID: 24050629 DOI: 10.1111/nph.12502] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- Nate G McDowell
- Earth and Environmental Sciences Division, Los Alamos National Lab, Los Alamos, NM, 87545, USA
| | - Michael G Ryan
- Natural Resource Ecology Lab, Colorado State University, Fort Collins, CO, 80523-1499, USA
- USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO, 80526, USA
| | - Melanie J B Zeppel
- Department of Biological Sciences, Macquarie University, 2109, Sydney, NSW, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, NSW, 2753, Australia
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