@article {5023, title = {Soil biota sensitivity to hydroclimate variability in a polar desert ecosystem}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {57}, year = {2025}, month = {05/2025}, abstract = {

An anomalous warm weather event in the Antarctic McMurdo Dry Valleys on 18 March 2022 created an opportunity to characterize soil biota communities most sensitive to freeze\–thaw stress. This event caused unseasonal melt within Taylor Valley, activating stream water and microbial mats around Canada Stream. Liquid water availability in this polar desert is a driver of soil biota distribution and activity. Because climate change impacts hydrological regimes, we aimed to determine the effect on soil communities. We sampled soils identified from this event that experienced thaw, nearby hyper-arid areas, and wetted areas that did not experience thaw to compare soil bacterial and invertebrate communities. Areas that exhibited evidence of freeze\–thaw supported the highest live and dead nematode counts and were composed of soil taxa from hyper-arid landscapes and wetted areas. They received water inputs from snowpacks, hyporheic water, or glacial melt, contributing to community differences associated with organic matter and salinity gradients. Inundated soils had higher organic matter and lower conductivity (p \<\ .02) and hosted the most diverse microbial and invertebrate communities on average. Our findings suggest that as liquid water becomes more available under predicted climate change, soil communities adapted to the hyper-arid landscape will shift toward diverse, wetted soil communities.

}, keywords = {LTER-MCM, climate variation, extreme weather, McMurdo Dry Valleys, microbial community, soil invertebrates}, issn = {1523-0430}, doi = {10.1080/15230430.2025.2485283}, url = {https://www.tandfonline.com/doi/full/10.1080/15230430.2025.2485283}, author = {Snyder, Meredith D. and Adams, Byron J. and Borgmeier, Abigail and Jorna, Jesse and Power, Sarah N. and Salvatore, Mark R. and John E. Barrett} } @article {4080, title = {Soil biological responses to C, N and P fertilization in a polar desert of Antarctica}, journal = {Soil Biology and Biochemistry}, volume = {122}, year = {2018}, month = {07/2018}, chapter = {7}, abstract = {

In the polar desert ecosystem of the McMurdo Dry Valleys of Antarctica, biology is constrained by available liquid water, low temperatures, as well as the availability of organic matter and nutrient elements. These soil ecosystems are climate-sensitive, where projected future warming may have profound effects on biological communities and biogeochemical cycling. Warmer temperatures will mobilize meltwater from permafrost and glaciers, may increase precipitation and may be accompanied by pulses of nutrient availability. Enhanced water and nutrient availability have the potential to greatly influence desert soil biology and ecosystem processes. The objectives of this 5-year study were to determine which nutrient elements (C, N, P) are most limiting to dry valley soil communities and whether landscape history (i.e.,\ in situ\ soil type and stoichiometry) influences soil community response to nutrient additions. After 3 years of no noticeable response, soil CO2\ flux was significantly higher under addition of C+ N than the other treatments, regardless of\ in situ\ soil stoichiometry, but microbial biomass and invertebrate abundance were variable and not influenced in the same manner. A stable isotope incubation suggests that fertilization increases C and N mineralization from organic matter via stimulating microbial activity, with loss of both the applied treatments as well\ in situ\ C and N. However, these responses are relatively short-lived, suggesting long-term impacts on C and N cycling would only occur if meltwater and nutrient pulses are sustained over time, a scenario that is increasingly likely for the dry valleys.

}, keywords = {LTER-MCM}, issn = {00380717}, doi = {10.1016/j.soilbio.2018.03.025}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0038071718301081}, author = {Ball, Becky and Byron Adams and John E. Barrett and Diana H. Wall and Ross A. Virginia} } @article {4059, title = {Stable C and N isotope ratios reveal soil food web structure and identify the nematode Eudorylaimus antarcticus as an omnivore{\textendash}predator in~Taylor Valley, Antarctica}, journal = {Polar Biology}, volume = {41}, year = {2018}, month = {05/2018}, pages = {1013{\textendash}1018}, abstract = {

Soil food webs of the McMurdo Dry Valleys, Antarctica are simple. These include primary trophic levels of mosses, algae, cyanobacteria, bacteria, archaea, and fungi, and their protozoan and metazoan consumers (including relatively few species of nematodes, tardigrades, rotifers, and microarthropods). These biota are patchily distributed across the landscape, with greatest faunal biodiversity associated with wet soil. Understanding trophic structure is critical to studies of biotic interactions and distribution; yet, McMurdo Dry Valley soil food web structure has been inferred from limited laboratory culturing and micro- scopic observations. To address this, we measured stable isotope natural abundance ratios of C (13C/12C) and N (15N/14N) for di erent metazoan taxa (using whole body biomass) to determine soil food web structure in Taylor Valley, Antarctica. Nitrogen isotopes were most useful in di erentiating trophic levels because they fractionated predictably at higher trophic levels. Using 15N/14N, we found that three trophic levels were present in wet soil habitats. While cyanobacterial mats were the primary trophic level, the nematode Plectus murrayi, tardigrade Acutuncus antarcticus, and rotifers composed a secondary trophic level of grazers. Eudorylaimus antarcticus had a 15N/14N ratio that was 2\–4\‰ higher than that of grazers, indicating that this species is the sole member of a tertiary trophic level. Understanding the trophic positions of soil fauna is critical to predictions of current and future species interactions and their distributions for the McMurdo Dry Valleys, Antarctica.

}, keywords = {LTER-MCM}, doi = {10.1007/s00300-017-2243-8}, url = {http://link.springer.com/10.1007/s00300-017-2243-8}, author = {Shaw, E. Ashley and Byron Adams and John E. Barrett and W. Berry Lyons and Ross A. Virginia and Diana H. Wall} } @article {4139, title = {Stoichiometric Shifts in Soil C:N:P Promote Bacterial Taxa Dominance, Maintain Biodiversity, and Deconstruct Community Assemblages}, journal = {Frontiers in Microbiology}, volume = {9}, year = {2018}, month = {07/2018}, abstract = {

Imbalances in C:N:P supply ratios may cause bacterial resource limitations and constrain biogeochemical processes, but the importance of shifts in soil stoichiometry are complicated by the nearly limitless interactions between an immensely rich species pool and a multiple chemical resource forms. To more clearly identify the impact of soil C:N:P on bacteria, we evaluated the cumulative effects of single and coupled long-term nutrient additions (i.e., C as mannitol, N as equal concentrations NH4 + and NO3 \− , and P as Na3PO4) and water on communities in an Antarctic polar desert, Taylor Valley. Untreated soils possessed relatively low bacterial diversity, simplified organic C sources due to the absence of plants, limited inorganic N, and excess soil P potentially attenuating links between C:N:P. After 6 years of adding resources, an alleviation of C and N colimitation allowed one rare Micrococcaceae, an Arthrobacter species, to dominate, comprising 47\% of the total community abundance and elevating soil respiration by 136\% relative to untreated soils. The addition of N alone reduced C:N ratios, elevated bacterial richness and diversity, and allowed rare taxa relying on ammonium and nitrite for metabolism to become more abundant [e.g., nitrite oxidizing Nitrospira species (Nitrosomonadaceae), denitrifiers utilizing nitrite (Gemmatimonadaceae) and members of Rhodobacteraceae with a high affinity for ammonium]. Based on community co-occurrence networks, lower C:P ratios in soils following P and CP additions created more diffuse and less connected communities by disrupting 73\% of species interactions and selecting for taxa potentially exploiting abundant P. Unlike amended nutrients, water additions alone elicited no lasting impact on communities. Our results suggest that as soils become nutrient rich a wide array of outcomes are possible from species dominance and the deconstruction of species interconnectedness to the maintenance of biodiversity.

}, keywords = {LTER-MCM, ecological stoichiometry, Lake Fryxell Basin, McMurdo Dry Valleys, network community modeling, nutrient colimitation, Solirubrobacteriaceae}, doi = {10.3389/fmicb.2018.01401}, url = {https://www.frontiersin.org/article/10.3389/fmicb.2018.01401/full}, author = {Aanderud, Zachary T. and Saurey, Sabrina D. and Ball, Becky and Diana H. Wall and John E. Barrett and Muscarella, Mario E. and Griffin, Natasha A. and Ross A. Virginia and Byron Adams} } @article {3965, title = {A simulation-based approach to understand how metacommunity characteristics influence emergent biodiversity patterns}, journal = {Oikos}, volume = {126}, year = {2017}, month = {05/2017}, pages = {723-737}, abstract = {

To understand controls over biodiversity, it is necessary to take a multi-scale approach to understand how local and regional factors a ect the community assembly processes that drive emergent patterns. \ is need is re ected in the growing use of the metacommunity concept to interpret multi-scale measures of biodiversity, including metrics derived from diversity partitioning (e.g. a, b and g diversity) and variation partitioning (e.g. spatial and environmental components of compositional turnover) techniques. However, studies have shown limited success using these metrics to characterize underlying community assembly dynamics. Here we demonstrate how a metacommunity simulation package (MCSim) can be used to evaluate when and how biodiversity metrics can be used to make inferences about metacommunity characteristics. We examined a wide range of parameter settings representing ecologically relevant scenarios. We used artificial neural networks (ANNs) to assess the sensitivity of diversity and variation partitioning metrics (calculated from simulation outcomes) to metacommunity parameter settings. In the scenarios examined in this study, the niche-neutral gradient strongly in uenced most biodiversity metrics, metacommunity size exhibited a marginal influence over some metrics, and dispersal dynamics only a ected a subset of variation partitioning outcomes. Variation partitioning response curves along the niche-neutral gradient were not monotonic; however, simulation outcomes suggest other biodiversity metrics (e.g. dissimilarity saturation) can be used in combination with variation partitioning metrics to make inferences about metacommunity properties. With the growing availability of archived ecological data, we expect future work will apply simulation-based techniques to better understand links between biodiversity and the metacommunity characteristics that are presumed to control the underlying community assembly processes.

}, keywords = {LTER-MCM}, doi = {10.1111/oik.03690}, url = {http://doi.wiley.com/10.1111/oik.03690}, author = {Eric R. Sokol and Brown, Bryan L. and John E. Barrett} } @article {1064, title = {Soil microbial responses to increased moisture and organic resources along a salinity gradient in a polar desert.}, journal = {Applied and Environmental Microbiology.}, volume = {80}, year = {2014}, month = {05/2014}, pages = {3034-3043}, chapter = {3034}, abstract = {Microbial communities in extreme environments often have low diversity and specialized physiologies suggesting a limited resistance to change. The McMurdo Dry Valleys (MDV) are a microbially dominated, extreme ecosystem currently undergoing climate change-induced disturbances, including the melting of massive buried ice, cutting through of permafrost by streams, and warming events. These processes are increasing moisture across the landscape, altering conditions for soil communities by mobilizing nutrients and salts and stimulating autotrophic carbon inputs to soils. The goal of this study was to determine the effects of resource addition (water/organic matter) on the composition and function of microbial communities in the MDV along a natural salinity gradient representing an additional gradient of stress in an already extreme environment. Soil respiration and the activity of carbon-acquiring extracellular enzymes increased significantly (P < 0.05) with the addition of resources at the low- and moderate-salinity sites but not the high-salinity site. The bacterial community composition was altered, with an increase in Proteobacteria and Firmicutes with water and organic matter additions at the low- and moderate-salinity sites and a near dominance of Firmicutes at the high-salinity site. Principal coordinate analyses of all samples using a phylogenetically informed distance matrix (UniFrac) demonstrated discrete clustering among sites (analysis of similarity [ANOSIM], P < 0.05 and R > 0.40) and among most treatments within sites. The results from this experimental work suggest that microbial communities in this environment will undergo rapid change in response to the altered resources resulting from climate change impacts occurring in this region.}, keywords = {LTER-MCM}, doi = {10.1128/AEM.03414-13}, author = {David J. Van Horn and Okie, J.G. and Heather N. Buelow and Michael N. Gooseff and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1089, title = {Seasonal controls on snow distribution and aerial ablation at the snow-patch and landscape scales, McMurdo Dry Valleys, Antarctica}, journal = {The Cryosphere}, volume = {7}, year = {2013}, month = {09/2013}, pages = {917 - 931}, keywords = {LTER-MCM}, doi = {10.5194/tc-7-917-2013}, url = {http://www.the-cryosphere.net/7/917/2013/tc-7-917-2013.html}, author = {Eveland, Jeffery and Michael N. Gooseff and Lampkin, Derrick J. and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1096, title = {Shallow groundwater systems in a polar desert, McMurdo Dry Valleys}, journal = {Hydrogeology Journal}, volume = {21}, year = {2013}, month = {02/2013}, pages = {171 - 183}, keywords = {LTER-MCM}, doi = {10.1007/s10040-012-0926-3}, url = {http://link.springer.com/article/10.1007\%2Fs10040-012-0926-3}, author = {Michael N. Gooseff and John E. Barrett and Joseph S. Levy} } @article {1090, title = {Spatial and temporal patterns of snow accumulation and aerial ablation across the McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, volume = {27}, year = {2013}, month = {09/2013}, pages = {2864 - 2875}, keywords = {LTER-MCM}, doi = {10.1002/hyp.9407}, url = {http://onlinelibrary.wiley.com/doi/10.1002/hyp.9407/pdf}, author = {Eveland, Jeffery and Michael N. Gooseff and Lampkin, Derrick J. and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1193, title = {Spatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems.}, journal = {Hydrology and Earth System Sciences}, volume = {13}, year = {2009}, pages = {2349-2358}, keywords = {LTER-MCM}, doi = {LTER}, author = {John E. Barrett and Michael N. Gooseff and Cristina D. Takacs-Vesbach} } @article {1194, title = {State of the Antarctic and the Southern Ocean climate system,}, journal = {Review of Geophysics}, volume = {47}, year = {2009}, keywords = {LTER-MCM}, doi = {LTER}, author = {Paul A. Mayewski and David Bromwich and Campbell, H and Hamilton, G and W. Berry Lyons and Maasch, K and Aoki, S and Xiao, C and van Ommen, T and Meredith, M and Summerhayes, C and Turner, J and Worby, A and John E. Barrett and Casassa, G and Bertler, N and T Bracegirdle} } @article {1233, title = {Soil phosphorus cycling in an Antarctic polar desert}, journal = {Geochimica et Cosmochimica Acta}, volume = {144}, year = {2008}, pages = {21-32}, keywords = {LTER-MCM}, doi = {LTER}, author = {D. Brad Bate and John E. Barrett and Poage, M and Ross A. Virginia} } @article {1283, title = {Salt tolerance and survival thresholds for two species of Antarctic soil nematodes}, journal = {Polar Biology}, volume = {29}, year = {2006}, pages = {643-651}, keywords = {LTER-MCM}, doi = {LTER}, author = {Johnson N. Nkem and Ross A. Virginia and John E. Barrett and Diana H. Wall and Li, G} } @article {1274, title = {Soil carbon turnover model for the McMurdo Dry Valleys, Antarctica}, journal = {Soil Biology and Biochemistry}, volume = {38}, year = {2006}, pages = {3065-3082}, keywords = {LTER-MCM}, doi = {LTER}, author = {John E. Barrett and Ross A. Virginia and Andrew N. Parsons and Diana H. Wall} } @article {1277, title = {A synthesis of soil biodiversity and ecosystem functioning in Victoria Land, Antarctica}, journal = {Soil Biology and Biochemistry}, volume = {38}, year = {2006}, pages = {3001-3002}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall and Byron Adams and John E. Barrett and D. W. Hopkins} } @article {1342, title = {Soil carbon dioxide flux from Antarctic Dry Valley soils}, journal = {Ecosystems}, volume = {7}, year = {2004}, pages = {286-295}, keywords = {LTER-MCM}, author = {Andrew N. Parsons and John E. Barrett and Diana H. Wall and Ross A. Virginia} } @article {1376, title = {Snow patch influence on soil biogeochemical processes and invertebrate distribution in the McMurdo Dry Valleys, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {35}, year = {2002}, month = {02/2003}, pages = {91-99}, type = {Journal}, keywords = {LTER-MCM, Biggie}, doi = {10.1657/1523-0430(2003)035[0091:SPIOSB]2.0.CO;2}, url = {http://instaar.metapress.com/content/r086455ju7213711/}, author = {Michael N. Gooseff and John E. Barrett and Peter T. Doran and Andrew G Fountain and W. Berry Lyons and Andrew N. Parsons and Porazinska, D and Ross A. Virginia and Diana H. Wall} }