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Elrys AS, Abo El-Maati MF, Dan X, Wen Y, Mou J, Abdelghany AE, Uwiragiye Y, Shuirong T, Yanzheng W, Meng L, Zhang J, Müller C. Aridity creates global thresholds in soil nitrogen retention and availability. GLOBAL CHANGE BIOLOGY 2024; 30:e17003. [PMID: 37943245 DOI: 10.1111/gcb.17003] [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: 07/31/2023] [Revised: 10/12/2023] [Accepted: 10/12/2023] [Indexed: 11/10/2023]
Abstract
Identifying tipping points in the relationship between aridity and gross nitrogen (N) cycling rates could show critical vulnerabilities of terrestrial ecosystems to climate change. Yet, the global pattern of gross N cycling response to aridity across terrestrial ecosystems remains unknown. Here, we collected 14,144 observations from 451 15 N-labeled studies and used segmented regression to identify the global threshold responses of soil gross N cycling rates and soil process-related variables to aridity index (AI), which decreases as aridity increases. We found on a global scale that increasing aridity reduced soil gross nitrate consumption but increased soil nitrification capacity, mainly due to reduced soil microbial biomass carbon (MBC) and N (MBN) and increased soil pH. Threshold response of gross N production and retention to aridity was observed across terrestrial ecosystems. In croplands, gross nitrification and extractable nitrate were inhibited with increasing aridity below the threshold AI ~0.8-0.9 due to inhibited ammonia-oxidizing archaea and bacteria, while the opposite was favored above this threshold. In grasslands, gross N mineralization and immobilization decreased with increasing aridity below the threshold AI ~0.5 due to decreased MBN, but the opposite was true above this threshold. In forests, increased aridity stimulated nitrate immobilization below the threshold AI ~1.0 due to increased soil C/N ratio, but inhibited ammonium immobilization above the threshold AI ~1.3 due to decreased soil total N and increased MBC/MBN ratio. Soil dissimilatory nitrate reduction to ammonium decreased with increasing aridity globally and in forests when the threshold AI ~1.4 was passed. Overall, we suggest that any projected increase in aridity in response to climate change is likely to reduce plant N availability in arid regions while enhancing it in humid regions, affecting the provision of ecosystem services and functions.
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Affiliation(s)
- Ahmed S Elrys
- College of Tropical Crops, Hainan University, Haikou, China
- Soil Science Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
- Liebig Centre for Agroecology and Climate Impact Research, Justus Liebig University, Giessen, Germany
| | - Mohamed F Abo El-Maati
- Agriculture Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Xiaoqian Dan
- College of Tropical Crops, Hainan University, Haikou, China
| | - YuHong Wen
- College of Tropical Crops, Hainan University, Haikou, China
| | - Jinxia Mou
- College of Tropical Crops, Hainan University, Haikou, China
| | - Ahmed Elsayed Abdelghany
- Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid, Areas of Ministry of Education, Northwest A&F University, Yangling, China
- Water Relation and Field Irrigation Department, Agriculture and Biological Institute, National Research Centre, Cairo, Egypt
| | - Yves Uwiragiye
- Department of Agriculture, Faculty of Agriculture, Environmental Management and Renewable Energy, University of Technology and Arts of Byumba, Byumba, Rwanda
- School of Geography, Nanjing Normal University, Nanjing, China
| | - Tang Shuirong
- College of Tropical Crops, Hainan University, Haikou, China
| | - Wu Yanzheng
- College of Tropical Crops, Hainan University, Haikou, China
| | - Lei Meng
- College of Tropical Crops, Hainan University, Haikou, China
| | - JinBo Zhang
- College of Tropical Crops, Hainan University, Haikou, China
- Liebig Centre for Agroecology and Climate Impact Research, Justus Liebig University, Giessen, Germany
- School of Geography, Nanjing Normal University, Nanjing, China
| | - Christoph Müller
- Liebig Centre for Agroecology and Climate Impact Research, Justus Liebig University, Giessen, Germany
- Institute of Plant Ecology, Justus Liebig University Giessen, Giessen, Germany
- School of Biology and Environmental Science and Earth Institute, University College Dublin, Dublin, Ireland
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Song Z, Wang X, Liu Y, Luo Y, Li Z. Allocation Strategies of Carbon, Nitrogen, and Phosphorus at Species and Community Levels With Recovery After Wildfire. FRONTIERS IN PLANT SCIENCE 2022; 13:850353. [PMID: 35481138 PMCID: PMC9037545 DOI: 10.3389/fpls.2022.850353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
Plant stoichiometry and nutrient allocation can reflect a plant's adaptation to environmental nutrient changes. However, the allocation strategies of carbon (C), nitrogen (N), and phosphorus (P) between leaf and fine root in response to wildfire have been poorly studied. Our primary objective was to elucidate the trade-off of elemental allocation between above- and belowground parts in response to the soil nutrient changes after a wildfire. We explored the allocation sloping exponents of C, N, and P between leaf and fine root at the species and community levels at four recovery periods (year 2, 10, 20, and 30) after moderately severe wildfire and one unburned treatment in boreal forests in Great Xing'an Mountains, northeast China. Compared with the unburned treatment, leaf C concentration decreased and fine root C increased at year 2 after recovery. The leaf N concentration at year 10 after recovery was higher than that of unburned treatment. Plant growth tended to be limited by P concentration at year 10 after recovery. Nutrient allocation between leaf and fine root differed between species and community levels, especially in the early recovery periods (i.e., 2 and 10 years). At the community level, the nutrient concentrations of the leaf changed more as compared to that of the fine root at year 2 after recovery when the fine root nutrients changed more than those of the leaf. The different C, N, and P allocation strategies advanced the understanding of plant adaptation to soil nutrient changes during the postfire ecosystem restoration.
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Affiliation(s)
- Zhaopeng Song
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, China
- College of Urban and Environmental Sciences, and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, China
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
| | - Xuemei Wang
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, China
| | - Yanhong Liu
- College of Urban and Environmental Sciences, and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, China
| | - Yiqi Luo
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
| | - Zhaolei Li
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, and Academy of Agricultural Sciences, Southwest University, Chongqing, China
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Fire Intensity Affects the Relationship between Species Diversity and the N Utilization Stability of Dominant Species. FORESTS 2019. [DOI: 10.3390/f10030207] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Stabilizing the local elemental stoichiometry is an important step toward restoring species diversity in a damaged ecosystem, especially those affected by wildfire. Stability of nitrogen (N) utilization is mainly affected by wildfire through restoration, which is one of the most important parts of stoichiometric utilization. However, the mechanisms underlying the relationship between N utilization stability and species diversity are not well understood in burned areas. We investigated variation in species diversity and in the stability of leaf N utilization of locally dominant tree species in a series of burned areas during early community restoration following wildfires of different intensities. This study shows that low fire intensity led to an increase in the soil N concentration, and significantly affected the utilization of leaf N. With higher fire intensity, the leaf N concentration first decreased, and then increased as fire intensity increased. The dominant trees showed more stable N utilization at a medium intensity, compared with other intensities, but the stability of N utilization was overall higher for the dominant species than for the regenerating pioneer species. We also concluded that other soil nutrients altered the stability of plant N utilization, which we found was closely related to species diversity during restoration. The Shannon index and N utilization stability in burned areas were most significantly correlated. The N utilization stability regulation between soil total nitrogen (STN) and leaf total nitrogen (LTN) (HSTN-LTN) of Betula platyphylla Suk (BPS) correlated significantly and positively with the increase of the Shannon index (H), but the HSMN-LTN of the dominant species correlated significantly and negatively with H.
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Moon JB, Wardrop DH, Smithwick EAH, Naithani KJ. Fine-scale spatial homogenization of microbial habitats: a multivariate index of headwater wetland complex condition. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01816. [PMID: 30326550 DOI: 10.1002/eap.1816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 07/11/2018] [Accepted: 09/05/2018] [Indexed: 06/08/2023]
Abstract
With growing public awareness that wetlands are important to society, there are intensifying efforts to understand the ecological condition of those wetlands that remain, and to develop indicators of wetland condition. Indicators based on soils are not well developed and are absent in some current assessment protocols; these could be advantageous, particularly for soils, which are complex habitats for plants, invertebrates, and microbial communities. In this study, we examine whether multivariate soil indicators, correlated with microbial biomass and community composition, can be used to distinguish reference standard (i.e., high condition) headwater wetland complexes from impacted headwater wetland complexes in central Pennsylvania, USA. Our reference standard sites existed in forested landscapes, while our impacted sites were situated in multi-use landscapes and were affected by a range of land-use legacies in the 1900s. We found that current assessment protocols are likely underrepresenting sampling needs to accurately represent site mean soil properties. On average, more samples were required to represent soil property means in reference standard sites compared to impacted sites. Reference standard and impacted sites also had noticeably different types of microbial habitats for the two multivariate soil indices assessed, and impacted sites were more homogenized in terms of the fine-scale (i.e., 1 and 5 m) spatial variability of these indices. Our study shows promise for the use of multivariate soil indices as indicators of wetland condition and provides insights into the sample sizes and scales at which soil sampling should occur during assessments. Future work is needed to test the generalizability of these findings across wetland types and ecoregions and establish definitive links between structural changes in microbial habitats and changes in wetland soil functioning.
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Affiliation(s)
- Jessica B Moon
- Riparia Center, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, 72701, USA
| | - Denice H Wardrop
- Riparia Center, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
- Department of Geography, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Erica A H Smithwick
- Department of Geography, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Kusum J Naithani
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, 72701, USA
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The Effect of Re-Planting Trees on Soil Microbial Communities in a Wildfire-Induced Subalpine Grassland. FORESTS 2017. [DOI: 10.3390/f8100385] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Smithwick EA, Baldwin DC, Naithani KJ. Grassland productivity in response to nutrient additions and herbivory is scale-dependent. PeerJ 2016; 4:e2745. [PMID: 27920956 PMCID: PMC5136131 DOI: 10.7717/peerj.2745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 11/01/2016] [Indexed: 11/20/2022] Open
Abstract
Vegetation response to nutrient addition can vary across space, yet studies that explicitly incorporate spatial pattern into experimental approaches are rare. To explore whether there are unique spatial scales (grains) at which grass response to nutrients and herbivory is best expressed, we imposed a large (∼3.75 ha) experiment in a South African coastal grassland ecosystem. In two of six 60 × 60 m grassland plots, we imposed a scaled sampling design in which fertilizer was added in replicated sub-plots (1 × 1 m, 2 × 2 m, and 4 × 4 m). The remaining plots either received no additions or were fertilized evenly across the entire area. Three of the six plots were fenced to exclude herbivory. We calculated empirical semivariograms for all plots one year following nutrient additions to determine whether the scale of grass response (biomass and nutrient concentrations) corresponded to the scale of the sub-plot additions and compared these results to reference plots (unfertilized or unscaled) and to plots with and without herbivory. We compared empirical semivariogram parameters to parameters from semivariograms derived from a set of simulated landscapes (neutral models). Empirical semivariograms showed spatial structure in plots that received multi-scaled nutrient additions, particularly at the 2 × 2 m grain. The level of biomass response was predicted by foliar P concentration and, to a lesser extent, N, with the treatment effect of herbivory having a minimal influence. Neutral models confirmed the length scale of the biomass response and indicated few differences due to herbivory. Overall, we conclude that interpretation of nutrient limitation in grasslands is dependent on the grain used to measure grass response and that herbivory had a secondary effect.
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Affiliation(s)
- Erica A.H. Smithwick
- Department of Geography and Intercollege Graduate Degree Program in Ecology, Pennsylvania State University, University Park, PA, United States
| | - Douglas C. Baldwin
- Department of Geography, Pennsylvania State University, University Park, PA, United States
| | - Kusum J. Naithani
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, United States
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Sun H, Santalahti M, Pumpanen J, Köster K, Berninger F, Raffaello T, Asiegbu FO, Heinonsalo J. Bacterial community structure and function shift across a northern boreal forest fire chronosequence. Sci Rep 2016; 6:32411. [PMID: 27573440 PMCID: PMC5004109 DOI: 10.1038/srep32411] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/09/2016] [Indexed: 11/09/2022] Open
Abstract
Soil microbial responses to fire are likely to change over the course of forest recovery. Investigations on long-term changes in bacterial dynamics following fire are rare. We characterized the soil bacterial communities across three different times post fire in a 2 to 152-year fire chronosequence by Illumina MiSeq sequencing, coupled with a functional gene array (GeoChip). The results showed that the bacterial diversity did not differ between the recently and older burned areas, suggesting a concomitant recovery in the bacterial diversity after fire. The differences in bacterial communities over time were mainly driven by the rare operational taxonomic units (OTUs < 0.1%). Proteobacteria (39%), Acidobacteria (34%) and Actinobacteria (17%) were the most abundant phyla across all sites. Genes involved in C and N cycling pathways were present in all sites showing high redundancy in the gene profiles. However, hierarchical cluster analysis using gene signal intensity revealed that the sites with different fire histories formed separate clusters, suggesting potential differences in maintaining essential biogeochemical soil processes. Soil temperature, pH and water contents were the most important factors in shaping the bacterial community structures and function. This study provides functional insight on the impact of fire disturbance on soil bacterial community.
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Affiliation(s)
- Hui Sun
- Collaborative Innovation Center of Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing, 210037, China.,Department of Food and Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland
| | - Minna Santalahti
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland
| | - Jukka Pumpanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, 70210, Finland
| | - Kajar Köster
- Department of Forest Sciences, University of Helsinki, Helsinki, 00790, Finland.,Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Tartu, 51014, Estonia
| | - Frank Berninger
- Department of Forest Sciences, University of Helsinki, Helsinki, 00790, Finland
| | - Tommaso Raffaello
- Department of Forest Sciences, University of Helsinki, Helsinki, 00790, Finland
| | - Fred O Asiegbu
- Department of Forest Sciences, University of Helsinki, Helsinki, 00790, Finland
| | - Jussi Heinonsalo
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland
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8
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Stephan K, Kavanagh KL, Koyama A. Comparing the influence of wildfire and prescribed burns on watershed nitrogen biogeochemistry using 15N natural abundance in terrestrial and aquatic ecosystem components. PLoS One 2015; 10:e0119560. [PMID: 25885257 PMCID: PMC4401779 DOI: 10.1371/journal.pone.0119560] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 01/14/2015] [Indexed: 11/19/2022] Open
Abstract
We evaluated differences in the effects of three low-severity spring prescribed burns and four wildfires on nitrogen (N) biogeochemistry in Rocky Mountain headwater watersheds. We compared paired (burned/unburned) watersheds of four wildfires and three spring prescribed burns for three growing seasons post-fire. To better understand fire effects on the entire watershed ecosystem, we measured N concentrations and δ15N in both the terrestrial and aquatic ecosystems components, i.e., soil, understory plants in upland and riparian areas, streamwater, and in-stream moss. In addition, we measured nitrate reductase activity in foliage of Spiraea betulifolia, a dominant understory species. We found increases of δ15N and N concentrations in both terrestrial and aquatic ecosystem N pools after wildfire, but responses were limited to terrestrial N pools after prescribed burns indicating that N transfer from terrestrial to aquatic ecosystem components did not occur in low-severity prescribed burns. Foliar δ15N differed between wildfire and prescribed burn sites; the δ15N of foliage of upland plants was enriched by 2.9 ‰ (difference between burned and unburned watersheds) in the first two years after wildfire, but only 1.3 ‰ after prescribed burns. In-stream moss δ15N in wildfire-burned watersheds was enriched by 1.3 ‰, but there was no response by moss in prescription-burned watersheds, mirroring patterns of streamwater nitrate concentrations. S. betulifolia showed significantly higher nitrate reductase activity two years after wildfires relative to corresponding unburned watersheds, but no such difference was found after prescribed burns. These responses are consistent with less altered N biogeochemistry after prescribed burns relative to wildfire. We concluded that δ15N values in terrestrial and aquatic plants and streamwater nitrate concentrations after fire can be useful indicators of the magnitude and duration of fire effects and the fate of post-fire available N.
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Affiliation(s)
- Kirsten Stephan
- Forest, Rangeland, and Fire Sciences, University of Idaho, Moscow, ID, United States of America
- Department of Life and Physical Sciences and Cooperative Research, Lincoln University, Jefferson City, Missouri, United States of America
| | - Kathleen L. Kavanagh
- Forest, Rangeland, and Fire Sciences, University of Idaho, Moscow, ID, United States of America
| | - Akihiro Koyama
- Forest, Rangeland, and Fire Sciences, University of Idaho, Moscow, ID, United States of America
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Wang C, Xiao H, Liu J, Wang L, Du D. Insights into Ecological Effects of Invasive Plants on Soil Nitrogen Cycles. ACTA ACUST UNITED AC 2015. [DOI: 10.4236/ajps.2015.61005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Naithani KJ, Ewers BE, Adelman JD, Siemens DH. Abiotic and biotic controls on local spatial distribution and performance of Boechera stricta. FRONTIERS IN PLANT SCIENCE 2014; 5:348. [PMID: 25101102 PMCID: PMC4106276 DOI: 10.3389/fpls.2014.00348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 06/28/2014] [Indexed: 06/03/2023]
Abstract
This study investigates the relative influence of biotic and abiotic factors on community dynamics using an integrated approach and highlights the influence of space on genotypic and phenotypic traits in plant community structure. We examined the relative influence of topography, environment, spatial distance, and intra- and interspecific interactions on spatial distribution and performance of Boechera stricta (rockcress), a close perennial relative of model plant Arabidopsis. First, using Bayesian kriging, we mapped the topography and environmental gradients and explored the spatial distribution of naturally occurring rockcress plants and two neighbors, Taraxacum officinale (dandelion) and Solidago missouriensis (goldenrod) found in close proximity within a typical diverse meadow community across topographic and environmental gradients. We then evaluated direct and indirect relationships among variables using Mantel path analysis and developed a network displaying abiotic and biotic interactions in this community. We found significant spatial autocorrelation among rockcress individuals, either because of common microhabitats as displayed by high density of individuals at lower elevation and high soil moisture area, or limited dispersal as shown by significant spatial autocorrelation of naturally occurring inbred lines, or a combination of both. Goldenrod and dandelion density around rockcress does not show any direct relationship with rockcress fecundity, possibly due to spatial segregation of resources. However, dandelion density around rockcress shows an indirect negative influence on rockcress fecundity via herbivory, indicating interspecific competition. Overall, we suggest that common microhabitat preference and limited dispersal are the main drivers for spatial distribution. However, intra-specific interactions and insect herbivory are the main drivers of rockcress performance in the meadow community.
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Affiliation(s)
- Kusum J. Naithani
- Program in Ecology, University of WyomingLaramie, WY, USA
- Department of Botany, University of WyomingLaramie, WY, USA
| | - Brent E. Ewers
- Program in Ecology, University of WyomingLaramie, WY, USA
- Department of Botany, University of WyomingLaramie, WY, USA
| | | | - David H. Siemens
- Department of Biology, Black Hills State UniversitySpearfish, SD, USA
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Buscardo E, Rodríguez-Echeverría S, Freitas H, De Angelis P, Pereira JS, Muller LAH. Contrasting soil fungal communities in Mediterranean pine forests subjected to different wildfire frequencies. FUNGAL DIVERS 2014. [DOI: 10.1007/s13225-014-0294-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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12
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Rapid recovery of soil bacterial communities after wildfire in a Chinese boreal forest. Sci Rep 2014; 4:3829. [PMID: 24452061 PMCID: PMC3899593 DOI: 10.1038/srep03829] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 01/06/2014] [Indexed: 11/08/2022] Open
Abstract
Fires affect hundreds of millions of hectares annually. Above-ground community composition and diversity after fire have been studied extensively, but effects of fire on soil bacterial communities remain largely unexamined despite the central role of bacteria in ecosystem recovery and functioning. We investigated responses of bacterial community to forest fire in the Greater Khingan Mountains, China, using tagged pyrosequencing. Fire altered soil bacterial community composition substantially and high-intensity fire significantly decreased bacterial diversity 1-year-after-burn site. Bacterial community composition and diversity returned to similar levels as observed in controls (no fire) after 11 years. The understory vegetation community typically takes 20-100 years to reach pre-fire states in boreal forest, so our results suggest that soil bacteria could recover much faster than plant communities. Finally, soil bacterial community composition significantly co-varied with soil pH, moisture content, NH4(+) content and carbon/nitrogen ratio (P < 0.05 in all cases) in wildfire-perturbed soils, suggesting that fire could indirectly affect bacterial communities by altering soil edaphic properties.
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