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Yelenik SG, Rehm EM, D'Antonio CM. Can the impact of canopy trees on soil and understory be altered using litter additions? ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e02477. [PMID: 34657347 DOI: 10.1002/eap.2477] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/13/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
Trees can have large effects on soil nutrients in ways that alter succession, particularly in the case of nitrogen-(N)-fixing trees. In Hawai'i, forest restoration relies heavily on use of a native N-fixing tree, Acacia koa (koa), but this species increases soil-available N and likely facilitates competitive dominance of exotic pasture grasses. In contrast, Metrosideros polymorpha ('ōhi'a), the dominant native tree in Hawai'i, is less often planted because it is slow growing; yet it is typically associated with lower soil N and grass biomass, and greater native understory recruitment. We experimentally tested whether it is possible to reverse high soil N under koa by adding 'ōhi'a litter, using additions of koa litter or no litter as controls, over 2.5 yr. We then quantified natural litterfall and decomposition rates of 'ōhi'a and koa litter to place litter additions in perspective. Finally, we quantified whether litter additions altered grass biomass and if this had effects on native outplants. Adding 'ōhi'a litter increased soil carbon, but increased rather than decreased inorganic soil N pools. Contrary to expectations, koa litter decomposed more slowly than 'ōhi'a, although it released more N per unit of litter. We saw no reduction in grass biomass due to 'ōhi'a litter addition, and no change in native outplanted understory survival or growth. We conclude that the high N soil conditions under koa are difficult to reverse. However, we also found that outplanted native woody species were able to decrease exotic grass biomass over time, regardless of the litter environment, making this a better strategy for lowering exotic species impacts.
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Affiliation(s)
- Stephanie G Yelenik
- U.S. Geological Survey, Pacific Island Ecosystems Research Center, Hawai'i National Park, Hawai'i, 96718, USA
| | - Evan M Rehm
- Department of Ecology, Evolution and Marine Biology, University of California at Santa Barbara, Santa Barbara, California, 93106, USA
| | - Carla M D'Antonio
- Department of Ecology, Evolution and Marine Biology, University of California at Santa Barbara, Santa Barbara, California, 93106, USA
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Abstract
Symbiotic nitrogen (N)-fixing trees supply significant N inputs to forest ecosystems, leading to increased soil fertility, forest growth, and carbon storage. Rapid growth and stoichiometric constraints of N fixers also create high demands for rock-derived nutrients such as phosphorus (P), while excess fixed N can generate acidity and accelerate leaching of rock-derived nutrients such as calcium (Ca). This ability of N-fixing trees to accelerate cycles of Ca, P, and other rock-derived nutrients has fostered speculation of a direct link between N fixation and mineral weathering in terrestrial ecosystems. However, field evidence that N-fixing trees have enhanced access to rock-derived nutrients is lacking. Here we use strontium (Sr) isotopes as a tracer of nutrient sources in a mixed-species temperate rainforest to show that N-fixing trees access more rock-derived nutrients than nonfixing trees. The N-fixing tree red alder (Alnus rubra), on average, took up 8 to 18% more rock-derived Sr than five co-occurring nonfixing tree species, including two with high requirements for rock-derived nutrients. The increased access to rock-derived nutrients occurred despite spatial variation in community-wide Sr sources across the forest, and only N fixers had foliar Sr isotopes that differed significantly from soil exchangeable pools. We calculate that increased uptake of rock-derived nutrients by N-fixing alder requires a 64% increase in weathering supply of nutrients over nonfixing trees. These findings provide direct evidence that an N-fixing tree species can also accelerate nutrient inputs from rock weathering, thus increasing supplies of multiple nutrients that limit carbon uptake and storage in forest ecosystems.
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Buma B, Thompson T. Long-term exposure to more frequent disturbances increases baseline carbon in some ecosystems: Mapping and quantifying the disturbance frequency-ecosystem C relationship. PLoS One 2019; 14:e0212526. [PMID: 30789951 PMCID: PMC6383921 DOI: 10.1371/journal.pone.0212526] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 02/04/2019] [Indexed: 11/25/2022] Open
Abstract
Disturbance regimes have a major influence on the baseline carbon that characterizes any particular ecosystem. Often regimes result in lower average regional baseline C (compared to those same systems if the disturbance processes were lessened/removed). However, in infrequently disturbed systems the role of disturbance as a “background” process that influences broad-scale, baseline C levels is often neglected. Long-term chronosequences suggest disturbances in these systems may serve to increase regional biomass C stocks by maintaining productivity. However, that inference has not been tested spatially. Here, the large forested system of southeast Alaska, USA, is utilized to 1) estimate baseline regional C stocks, 2) test the fundamental disturbance-ecosystem C relationship, 3) estimate the cumulative impact of disturbances on baseline C. Using 1491 ground points with carbon measurements and a novel way of mapping disturbance regimes, the relationship between total biomass C, disturbance exposure, and climate was analyzed statistically. A spatial model was created to determine regional C and compare different disturbance scenarios. In this infrequently disturbed ecosystem, higher disturbance exposure is correlated with higher biomass C, supporting the hypothesis that disturbances maintain productivity at broad scales. The region is estimated to potentially contain a baseline 1.21–1.52 Pg biomass C (when unmanaged). Removal of wind and landslides from the model resulted in lower net C stocks (-2 to -19% reduction), though the effect was heterogeneous on finer scales. There removal of landslides alone had a larger effect then landslide and wind combined removal. The relationship between higher disturbance exposure and higher biomass within the broad ecosystem (which, on average, has a very low disturbance frequency) suggest that disturbances can serve maintain higher levels of productivity in infrequently disturbed but very C dense ecosystems. Carbon research in other systems, especially those where disturbances are infrequent relative to successional processes, should consider the role of disturbances in maintaining baseline ecosystem productivity.
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Affiliation(s)
- Brian Buma
- Department of Integrative Biology, University of Colorado, Denver, United States of America
- * E-mail:
| | - Thomas Thompson
- USDA Forest Service, Resource Monitoring and Assessment Program, PNW Research Station, Anchorage, AK, United States of America
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4
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Wilcots ME, Taylor BN, Kuprewicz EK, Menge DNL. Small traits with big consequences: how seed traits of nitrogen‐fixing plants might influence ecosystem nutrient cycling. OIKOS 2018. [DOI: 10.1111/oik.05798] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Megan E. Wilcots
- Ecology, Evolution and Environmental Biology, Columbia Univ., 1200 Amsterdam Ave New York NY 10027 USA
| | - Benton N. Taylor
- Ecology, Evolution and Environmental Biology, Columbia Univ., 1200 Amsterdam Ave New York NY 10027 USA
| | - Erin K. Kuprewicz
- Ecology and Evolutionary Biology, Univ. of Connecticut Storrs CT USA
| | - Duncan N. L. Menge
- Ecology, Evolution and Environmental Biology, Columbia Univ., 1200 Amsterdam Ave New York NY 10027 USA
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5
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Isotopic evidence for oligotrophication of terrestrial ecosystems. Nat Ecol Evol 2018; 2:1735-1744. [DOI: 10.1038/s41559-018-0694-0] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 09/12/2018] [Indexed: 11/09/2022]
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6
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Meghdadi A, Javar N. Evaluation of nitrate sources and the percent contribution of bacterial denitrification in hyporheic zone using isotope fractionation technique and multi-linear regression analysis. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2018; 222:54-65. [PMID: 29802986 DOI: 10.1016/j.jenvman.2018.05.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 06/08/2023]
Abstract
Denitrification has documented as a promising pathway to permanently remove nitrate from a system. Numerous studies have used the isotope fractionation technique (IFT) to evaluate the denitrification rate in the constructed wetlands (CWs), but the potential of IFT method to quantify the denitrification rate in hyporheic zone (saturated sediments beneath a stream) is still challenging. Thus, more studies are required to investigate that if measurements of the natural abundance of δ15N-NO3- and δ18O-NO3- (IFT) can be employed to calculate the fate of nitrate in hyporheic zone. Therefore, in this study, the possibility of the IFT to quantify the hyporheic-denitrification rate was investigated. Then, the results were verified by the combined application of the pre-established net Sediment N2 flux and multi-linear regression analysis (p < 0.01). Finally, the groundwater bacterial groups (Fecal coliform (FC) and Escherichia coli (EC)), and the mass balance isotope mixing model were used to investigate the dominant sources of hyporheic-nitrate. The IFT reveals that denitrification contributes 74.1% and 29.1% of the hyporheic-nitrate removal during dry and wet seasons, respectively. The multi-linear regression analysis, considering at 99% confidence interval (R2 = 92.1%; n = 44; p < 0.01), slightly overestimates the rate and the percent contribution of denitrification in the dry season (475.15 ± 101.18 μmol/m2d; 80.7%) and underestimates it during the wet season (205.072 ± 35.39 μmol/m2d; 24.01%). The analysis of EC and FC demonstrates that manure (41.9 ± 4.2%) and sewage (54.1 ± 8.9%) are the dominant contributors of the hyporheic-nitrate load. In addition, the results achieved by the analysis of the fecal bacterial indicators (EC and FC) were confirmed by NO3-/Cl- vs Cl- diagram. This study provides an alternative-initiative framework to accurately quantify the spatio-seasonal variations in the hyporheic-nitrate sources and hyporheic-denitrification rate that enables decision-makers to apply appropriate and targeted strategies to regulate nitrate load in river-aquifer systems.
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Affiliation(s)
- Aminreza Meghdadi
- Science and Engineering Faculty, School of Earth Environmental and Biological Science, Queensland University of Technology, GPO Box 2434, Brisbane, 4001, QLD, Australia.
| | - Narmin Javar
- School of Environmental and Biological Science (SEBS), Islamic Azad University, Zanjan Branch, Zanjan, Iran.
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Burton JI, Perakis SS, McKenzie SC, Lawrence CE, Puettmann KJ. Intraspecific variability and reaction norms of forest understorey plant species traits. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12898] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Julia I. Burton
- Department of Wildland Resources Utah State University Logan UT USA
| | - Steven S. Perakis
- U.S. Geological Survey Forest and Rangeland Ecosystem Science Center Corvallis OR USA
| | - Sean C. McKenzie
- Department of Land Resources and Environmental Sciences Montana State University Bozeman MT USA
| | | | - Klaus J. Puettmann
- Department of Forest Ecosystems and Society Oregon State University Corvallis OR USA
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8
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Creutzburg MK, Scheller RM, Lucash MS, LeDuc SD, Johnson MG. Forest management scenarios in a changing climate: trade-offs between carbon, timber, and old forest. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:503-518. [PMID: 27767233 DOI: 10.1002/eap.1460] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 09/07/2016] [Accepted: 09/12/2016] [Indexed: 05/13/2023]
Abstract
Balancing economic, ecological, and social values has long been a challenge in the forests of the Pacific Northwest, where conflict over timber harvest and old-growth habitat on public lands has been contentious for the past several decades. The Northwest Forest Plan, adopted two decades ago to guide management on federal lands, is currently being revised as the region searches for a balance between sustainable timber yields and habitat for sensitive species. In addition, climate change imposes a high degree of uncertainty on future forest productivity, sustainability of timber harvest, wildfire risk, and species habitat. We evaluated the long-term, landscape-scale trade-offs among carbon (C) storage, timber yield, and old forest habitat given projected climate change and shifts in forest management policy across 2.1 million hectares of forests in the Oregon Coast Range. Projections highlight the divergence between private and public lands under business-as-usual forest management, where private industrial forests are heavily harvested and many public (especially federal) lands increase C and old forest over time but provide little timber. Three alternative management scenarios altering the amount and type of timber harvest show widely varying levels of ecosystem C and old-forest habitat. On federal lands, ecological forestry practices also allowed a simultaneous increase in old forest and natural early-seral habitat. The ecosystem C implications of shifts away from current practices were large, with current practices retaining up to 105 Tg more C than the alternative scenarios by the end of the century. Our results suggest climate change is likely to increase forest productivity by 30-41% and total ecosystem C storage by 11-15% over the next century as warmer winter temperatures allow greater forest productivity in cooler months. These gains in C storage are unlikely to be offset by wildfire under climate change, due to the legacy of management and effective fire suppression. Our scenarios of future conditions can inform policy makers, land managers, and the public about the potential effects of land management alternatives, climate change, and the trade-offs that are inherent to management and policy in the region.
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Affiliation(s)
- Megan K Creutzburg
- Department of Environmental Science and Management, Portland State University, P.O. Box 751, Portland, Oregon, 97207, USA
| | - Robert M Scheller
- Department of Environmental Science and Management, Portland State University, P.O. Box 751, Portland, Oregon, 97207, USA
| | - Melissa S Lucash
- Department of Environmental Science and Management, Portland State University, P.O. Box 751, Portland, Oregon, 97207, USA
| | - Stephen D LeDuc
- National Center for Environmental Assessment, U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW (8623P), Washington, D.C., 20460, USA
| | - Mark G Johnson
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, Oregon, 97333, USA
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Hynicka JD, Pett-Ridge JC, Perakis SS. Nitrogen enrichment regulates calcium sources in forests. GLOBAL CHANGE BIOLOGY 2016; 22:4067-4079. [PMID: 27135298 DOI: 10.1111/gcb.13335] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 04/15/2016] [Accepted: 04/20/2016] [Indexed: 06/05/2023]
Abstract
Nitrogen (N) is a key nutrient that shapes cycles of other essential elements in forests, including calcium (Ca). When N availability exceeds ecosystem demands, excess N can stimulate Ca leaching and deplete Ca from soils. Over the long term, these processes may alter the proportion of available Ca that is derived from atmospheric deposition vs. bedrock weathering, which has fundamental consequences for ecosystem properties and nutrient supply. We evaluated how landscape variation in soil N, reflecting long-term legacies of biological N fixation, influenced plant and soil Ca availability and ecosystem Ca sources across 22 temperate forests in Oregon. We also examined interactions between soil N and bedrock Ca using soil N gradients on contrasting basaltic vs. sedimentary bedrock that differed 17-fold in underlying Ca content. We found that low-N forests on Ca-rich basaltic bedrock relied strongly on Ca from weathering, but that soil N enrichment depleted readily weatherable mineral Ca and shifted forest reliance toward atmospheric Ca. Forests on Ca-poor sedimentary bedrock relied more consistently on atmospheric Ca across all levels of soil N enrichment. The broad importance of atmospheric Ca was unexpected given active regional uplift and erosion that are thought to rejuvenate weathering supply of soil minerals. Despite different Ca sources to forests on basaltic vs. sedimentary bedrock, we observed consistent declines in plant and soil Ca availability with increasing N, regardless of the Ca content of underlying bedrock. Thus, traditional measures of Ca availability in foliage and soil exchangeable pools may poorly reflect long-term Ca sources that sustain soil fertility. We conclude that long-term soil N enrichment can deplete available Ca and cause forests to rely increasingly on Ca from atmospheric deposition, which may limit ecosystem Ca supply in an increasingly N-rich world.
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Affiliation(s)
- Justin D Hynicka
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR, 97331, USA
- Department of Crop and Soil Science, Oregon State University, Corvallis, OR, 97331, USA
| | - Julie C Pett-Ridge
- Department of Crop and Soil Science, Oregon State University, Corvallis, OR, 97331, USA
| | - Steven S Perakis
- Forest and Rangeland Ecosystem Science Center, U.S. Geological Survey, Corvallis, OR, 97331, USA
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10
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Riparian Soil Development Linked to Forest Succession Above and Below Dams Along the Elwha River, Washington, USA. Ecosystems 2016. [DOI: 10.1007/s10021-016-0080-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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Gautam MK, Lee KS, Song BY, Lee D, Bong YS. Early-stage changes in natural (13)C and (15)N abundance and nutrient dynamics during different litter decomposition. JOURNAL OF PLANT RESEARCH 2016; 129:463-476. [PMID: 26915037 DOI: 10.1007/s10265-016-0798-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 12/04/2015] [Indexed: 06/05/2023]
Abstract
Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems.
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Affiliation(s)
- Mukesh Kumar Gautam
- Division of Earth and Environmental Science, Korea Basic Science Institute (KBSI), 162 Yeongudanji-ro, Ochang-eup, Cheongju, Chungcheongbuk-do, 363-886, Republic of Korea
- , 2081 Wallace Avenue, Bronx, NY, 10462, USA
| | - Kwang-Sik Lee
- Division of Earth and Environmental Science, Korea Basic Science Institute (KBSI), 162 Yeongudanji-ro, Ochang-eup, Cheongju, Chungcheongbuk-do, 363-886, Republic of Korea.
| | - Byeong-Yeol Song
- Division of Earth and Environmental Science, Korea Basic Science Institute (KBSI), 162 Yeongudanji-ro, Ochang-eup, Cheongju, Chungcheongbuk-do, 363-886, Republic of Korea
- Chemical Analysis Division, National Forensic Service, Wonju, 220-170, Republic of Korea
| | - Dongho Lee
- Division of Earth and Environmental Science, Korea Basic Science Institute (KBSI), 162 Yeongudanji-ro, Ochang-eup, Cheongju, Chungcheongbuk-do, 363-886, Republic of Korea
| | - Yeon-Sik Bong
- Division of Earth and Environmental Science, Korea Basic Science Institute (KBSI), 162 Yeongudanji-ro, Ochang-eup, Cheongju, Chungcheongbuk-do, 363-886, Republic of Korea
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Kranabetter JM, McLauchlan KK, Enders SK, Fraterrigo JM, Higuera PE, Morris JL, Rastetter EB, Barnes R, Buma B, Gavin DG, Gerhart LM, Gillson L, Hietz P, Mack MC, McNeil B, Perakis S. A Framework to Assess Biogeochemical Response to Ecosystem Disturbance Using Nutrient Partitioning Ratios. Ecosystems 2015. [DOI: 10.1007/s10021-015-9934-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Mnich ME, Houlton BZ. Evidence for a uniformly small isotope effect of nitrogen leaching loss: results from disturbed ecosystems in seasonally dry climates. Oecologia 2015; 181:323-33. [DOI: 10.1007/s00442-015-3433-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 08/17/2015] [Indexed: 11/24/2022]
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14
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Perakis SS, Tepley AJ, Compton JE. Disturbance and Topography Shape Nitrogen Availability and δ15N over Long-Term Forest Succession. Ecosystems 2015. [DOI: 10.1007/s10021-015-9847-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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Convergence of soil nitrogen isotopes across global climate gradients. Sci Rep 2015; 5:8280. [PMID: 25655192 PMCID: PMC4319163 DOI: 10.1038/srep08280] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 01/06/2015] [Indexed: 12/03/2022] Open
Abstract
Quantifying global patterns of terrestrial nitrogen (N) cycling is central to predicting future patterns of primary productivity, carbon sequestration, nutrient fluxes to aquatic systems, and climate forcing. With limited direct measures of soil N cycling at the global scale, syntheses of the 15N:14N ratio of soil organic matter across climate gradients provide key insights into understanding global patterns of N cycling. In synthesizing data from over 6000 soil samples, we show strong global relationships among soil N isotopes, mean annual temperature (MAT), mean annual precipitation (MAP), and the concentrations of organic carbon and clay in soil. In both hot ecosystems and dry ecosystems, soil organic matter was more enriched in 15N than in corresponding cold ecosystems or wet ecosystems. Below a MAT of 9.8°C, soil δ15N was invariant with MAT. At the global scale, soil organic C concentrations also declined with increasing MAT and decreasing MAP. After standardizing for variation among mineral soils in soil C and clay concentrations, soil δ15N showed no consistent trends across global climate and latitudinal gradients. Our analyses could place new constraints on interpretations of patterns of ecosystem N cycling and global budgets of gaseous N loss.
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Dunnette PV, Higuera PE, McLauchlan KK, Derr KM, Briles CE, Keefe MH. Biogeochemical impacts of wildfires over four millennia in a Rocky Mountain subalpine watershed. THE NEW PHYTOLOGIST 2014; 203:900-912. [PMID: 24803372 DOI: 10.1111/nph.12828] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/31/2014] [Indexed: 06/03/2023]
Abstract
Wildfires can significantly alter forest carbon (C) storage and nitrogen (N) availability, but the long-term biogeochemical legacy of wildfires is poorly understood. We obtained a lake-sediment record of fire and biogeochemistry from a subalpine forest in Colorado, USA, to examine the nature, magnitude, and duration of decadal-scale, fire-induced ecosystem change over the past c. 4250 yr. The high-resolution record contained 34 fires, including 13 high-severity events within the watershed. High-severity fires were followed by increased sedimentary N stable isotope ratios (δ15N) and bulk density, and decreased C and N concentrations--reflecting forest floor destruction, terrestrial C and N losses, and erosion. Sustained low sediment C : N c. 20-50 yr post-fire indicates reduced terrestrial organic matter subsidies to the lake. Low sedimentary δ15N c. 50-70 yr post-fire, coincident with C and N recovery, suggests diminishing terrestrial N availability during stand development. The magnitude of post-fire changes generally scaled directly with inferred fire severity. Our results support modern studies of forest successional C and N accumulation and indicate pronounced, long-lasting biogeochemical impacts of wildfires in subalpine forests. However, even repeated high-severity fires over millennia probably did not deplete C or N stocks, because centuries between high-severity fires allowed for sufficient biomass recovery.
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Affiliation(s)
- Paul V Dunnette
- College of Natural Resources, University of Idaho, PO Box 441133, Moscow, ID, 83844-1133, USA
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17
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McLauchlan KK, Higuera PE, Gavin DG, Perakis SS, Mack MC, Alexander H, Battles J, Biondi F, Buma B, Colombaroli D, Enders SK, Engstrom DR, Hu FS, Marlon JR, Marshall J, McGlone M, Morris JL, Nave LE, Shuman B, Smithwick EAH, Urrego DH, Wardle DA, Williams CJ, Williams JJ. Reconstructing Disturbances and Their Biogeochemical Consequences over Multiple Timescales. Bioscience 2014. [DOI: 10.1093/biosci/bit017] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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18
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Perakis SS, Sinkhorn ER, Catricala CE, Bullen TD, Fitzpatrick JA, Hynicka JD, Cromack K. Forest calcium depletion and biotic retention along a soil nitrogen gradient. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2013; 23:1947-1961. [PMID: 24555320 DOI: 10.1890/12-2204.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
High nitrogen (N) accumulation in terrestrial ecosystems can shift patterns of nutrient limitation and deficiency beyond N toward other nutrients, most notably phosphorus (P) and base cations (calcium [Ca], magnesium [Mg], and potassium [K]). We examined how naturally high N accumulation from a legacy of symbiotic N fixation shaped P and base cation cycling across a gradient of nine temperate conifer forests in the Oregon Coast Range. We were particularly interested in whether long-term legacies of symbiotic N fixation promoted coupled N and organic P accumulation in soils, and whether biotic demands by non-fixing vegetation could conserve ecosystem base cations as N accumulated. Total soil N (0-100 cm) pools increased nearly threefold across the N gradient, leading to increased nitrate leaching, declines in soil pH from 5.8 to 4.2, 10-fold declines in soil exchangeable Ca, Mg, and K, and increased mobilization of aluminum. These results suggest that long-term N enrichment had acidified soils and depleted much of the readily weatherable base cation pool. Soil organic P increased with both soil N and C across the gradient, but soil inorganic P, biomass P, and P leaching loss did not vary with N, implying that historic symbiotic N fixation promoted soil organic P accumulation and P sufficiency for non-fixers. Even though soil pools of Ca, Mg, and K all declined as soil N increased, only Ca declined in biomass pools, suggesting the emergence of Ca deficiency at high N. Biotic conservation and tight recycling of Ca increased in response to whole-ecosystem Ca depletion, as indicated by preferential accumulation of Ca in biomass and surface soil. Our findings support a hierarchical model of coupled N-Ca cycling under long-term soil N enrichment, whereby ecosystem-level N saturation and nitrate leaching deplete readily available soil Ca, stimulating biotic Ca conservation as overall supply diminishes. We conclude that a legacy of biological N fixation can increase N and P accumulation in soil organic matter to the point that neither nutrient is limiting to subsequent non-fixers, while also resulting in natural N saturation that intensifies base cation depletion and deficiency.
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Affiliation(s)
- Steven S Perakis
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon 97331, USA.
| | - Emily R Sinkhorn
- Oregon State University, Department of Forest Ecosystems and Society, Corvallis, Oregon 97331, USA
| | - Christina E Catricala
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon 97331, USA
| | - Thomas D Bullen
- U.S. Geological Survey, National Research Program, Menlo Park, California 94025, USA
| | - John A Fitzpatrick
- U.S. Geological Survey, National Research Program, Menlo Park, California 94025, USA
| | - Justin D Hynicka
- Oregon State University, Department of Forest Ecosystems and Society, Corvallis, Oregon 97331, USA
| | - Kermit Cromack
- Oregon State University, Department of Forest Ecosystems and Society, Corvallis, Oregon 97331, USA
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19
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Yelenik S, Perakis S, Hibbs D. Regional constraints to biological nitrogen fixation in post-fire forest communities. Ecology 2013; 94:739-50. [PMID: 23687899 DOI: 10.1890/12-0278.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Biological nitrogen fixation (BNF) is a key ecological process that can restore nitrogen (N) lost in wildfire and shape the pace and pattern of post-fire forest recovery. To date, there is limited information on how climate and soil fertility interact to influence different pathways of BNF in early forest succession. We studied asymbiotic (forest floor and soil) and symbiotic (the shrub Ceanothus integerrimus) BNF rates across six sites in the Klamath National Forest, California, USA. We used combined gradient and experimental phosphorus (P) fertilization studies to explore cross-site variation in BNF rates and then related these rates to abiotic and biotic variables. We estimate that our measured BNF rates 22 years after wildfire (6.1-12.1 kg N x ha(-1) x yr(-1)) are unlikely to fully replace wildfire N losses. We found that asymbiotic BNF is P limited, although this is not the case for symbiotic BNF in Ceanothus. In contrast, Ceanothus BNF is largely driven by competition from other vegetation: in high-productivity sites with high potential evapotranspiration (Et), shrub biomass is suppressed as tree biomass increases. Because shrub biomass governed cross-site variation in Ceanothus BNF, this competitive interaction led to lower BNF in sites with high productivity and Et. Overall, these results suggest that the effects of nutrients play a larger role in driving asymbiotic than symbiotic fixation across our post-fire sites. However, because symbiotic BNF is 8-90x greater than asymbiotic BNF, it is interspecific plant competition that governs overall BNF inputs in these forests.
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Affiliation(s)
- Stephanie Yelenik
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, Oregon 97331, USA.
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20
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Vitousek PM, Menge DNL, Reed SC, Cleveland CC. Biological nitrogen fixation: rates, patterns and ecological controls in terrestrial ecosystems. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130119. [PMID: 23713117 DOI: 10.1098/rstb.2013.0119] [Citation(s) in RCA: 255] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
New techniques have identified a wide range of organisms with the capacity to carry out biological nitrogen fixation (BNF)-greatly expanding our appreciation of the diversity and ubiquity of N fixers-but our understanding of the rates and controls of BNF at ecosystem and global scales has not advanced at the same pace. Nevertheless, determining rates and controls of BNF is crucial to placing anthropogenic changes to the N cycle in context, and to understanding, predicting and managing many aspects of global environmental change. Here, we estimate terrestrial BNF for a pre-industrial world by combining information on N fluxes with (15)N relative abundance data for terrestrial ecosystems. Our estimate is that pre-industrial N fixation was 58 (range of 40-100) Tg N fixed yr(-1); adding conservative assumptions for geological N reduces our best estimate to 44 Tg N yr(-1). This approach yields substantially lower estimates than most recent calculations; it suggests that the magnitude of human alternation of the N cycle is substantially larger than has been assumed.
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Affiliation(s)
- Peter M Vitousek
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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21
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Changes in global nitrogen cycling during the Holocene epoch. Nature 2013; 495:352-5. [PMID: 23518563 DOI: 10.1038/nature11916] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 01/15/2013] [Indexed: 11/08/2022]
Abstract
Human activities have doubled the pre-industrial supply of reactive nitrogen on Earth, and future rates of increase are expected to accelerate. Yet little is known about the capacity of the biosphere to buffer increased nitrogen influx. Past changes in global ecosystems following deglaciation at the end of the Pleistocene epoch provide an opportunity to understand better how nitrogen cycling in the terrestrial biosphere responded to changes in carbon cycling. We analysed published records of stable nitrogen isotopic values (δ(15)N) in sediments from 86 lakes on six continents. Here we show that the value of sedimentary δ(15)N declined from 15,000 years before present to 7,056 ± 597 years before present, a period of increasing atmospheric carbon dioxide concentrations and terrestrial carbon accumulation. Comparison of the nitrogen isotope record with concomitant carbon accumulation on land and nitrous oxide in the atmosphere suggests millennia of declining nitrogen availability in terrestrial ecosystems during the Pleistocene-Holocene transition around 11,000 years before present. In contrast, we do not observe a consistent change in global sedimentary δ(15)N values during the past 500 years, despite the potential effects of changing temperature and nitrogen influx from anthropogenic sources. We propose that the lack of a single response may indicate that modern increases in atmospheric carbon dioxide and net carbon sequestration in the biosphere have the potential to offset recent increased supplies of reactive nitrogen in some ecosystems.
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22
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Perakis SS, Matkins JJ, Hibbs DE. N2-Fixing Red Alder Indirectly Accelerates Ecosystem Nitrogen Cycling. Ecosystems 2012. [DOI: 10.1007/s10021-012-9579-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Perakis SS, Matkins JJ, Hibbs DE. Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin-rich conifer litter. Ecosphere 2012. [DOI: 10.1890/es11-00340.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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