<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Power, Sarah N.</style></author><author><style face="normal" font="default" size="100%">Osburn, Ernest D.</style></author><author><style face="normal" font="default" size="100%">John E. Barrett</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Microbial mat activity and soil biogeochemistry across variable phosphorus availability in Taylor Valley, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">Antarctic Science</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">carbon</style></keyword><keyword><style  face="normal" font="default" size="100%">cyanobacteria</style></keyword><keyword><style  face="normal" font="default" size="100%">nitrogen fixation</style></keyword><keyword><style  face="normal" font="default" size="100%">phosphorus</style></keyword><keyword><style  face="normal" font="default" size="100%">pigments</style></keyword><keyword><style  face="normal" font="default" size="100%">soil ecology</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2025</style></year><pub-dates><date><style  face="normal" font="default" size="100%">05/2025</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://www.cambridge.org/core/journals/antarctic-science/article/microbial-mat-activity-and-soil-biogeochemistry-across-variable-phosphorus-availability-in-taylor-valley-antarctica/0655E2F09B8D6961618B8F396BA692F2</style></url></web-urls></urls><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Primary production is fundamental to ecosystems, and in many extreme environments production is facilitated by microbial mats. Microbial mats are complex assemblages of photo- and heterotrophic microorganisms colonizing sediment and soil surfaces. These communities are the dominant producers of the McMurdo Dry Valleys, Antarctica, where they occupy lentic and lotic environments as well as intermittently wet soils. While the influence of microbial mats on stream nutrient dynamics and lake organic matter cycling is well documented, the influence of microbial mats on underlying soil is less well understood, particularly the effects of microbial mat nitrogen and carbon fixation. Taylor Valley soils occur across variable levels of inorganic phosphorus availability, with the Ross Sea drift containing four times that of the Taylor drifts, providing opportunities to examine how soil geochemistry influences microbial mats and the ecological functions they regulate. We found that inorganic phosphorus availability is positively correlated with microbial mat biomass, pigment concentration and nitrogen fixation potential. Additionally, our results demonstrate that dense microbial mats influence the ecological functioning of underlying soils by enriching organic carbon and total nitrogen stocks (two times higher). This work contributes to ongoing questions regarding the sources of energy fuelling soil food webs and the regional carbon balance in the McMurdo Dry Valleys.&lt;/p&gt;</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Power, Sarah N.</style></author><author><style face="normal" font="default" size="100%">Thomas, Valerie A.</style></author><author><style face="normal" font="default" size="100%">Salvatore, Mark R.</style></author><author><style face="normal" font="default" size="100%">John E. Barrett</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Habitat suitability of biocrust communities in a cold desert ecosystem</style></title><secondary-title><style face="normal" font="default" size="100%">Ecology and Evolution</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">biocrust</style></keyword><keyword><style  face="normal" font="default" size="100%">carbon</style></keyword><keyword><style  face="normal" font="default" size="100%">dryland</style></keyword><keyword><style  face="normal" font="default" size="100%">habitat suitability</style></keyword><keyword><style  face="normal" font="default" size="100%">remote sensing</style></keyword><keyword><style  face="normal" font="default" size="100%">soil ecology</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2024</style></year><pub-dates><date><style  face="normal" font="default" size="100%">07/2024</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://onlinelibrary.wiley.com/toc/20457758/14/7</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">14</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Drylands are unique among terrestrial ecosystems in that they have a significant proportion of primary production facilitated by non-vascular plants such as colonial cyanobacteria, moss, and lichens, i.e., biocrusts, which occur on and in the surface soil. Biocrusts inhabit all continents, including Antarctica, an increasingly dynamic continent on the precipice of change. Here, we describe in-situ field surveying and sampling, remote sensing, and modeling approaches to assess the habitat suitability of biocrusts in the Lake Fryxell basin of Taylor Valley, Antarctica, which is the main site of the McMurdo Dry Valleys Long-Term Ecological Research Program. Soils suitable for the development of biocrusts are typically wetter, less alkaline, and less saline compared to unvegetated soils. Using random forest models, we show that gravimetric water content, electrical conductivity, and snow frequency are the top predictors of biocrust presence and biomass. Areas most suitable for the growth of dense biocrusts are soils associated with seasonal snow patches. Using geospatial data to extrapolate our habitat suitability model to the whole basin predicts that biocrusts are present in 2.7 &amp;times; 10&lt;sup&gt;5&lt;/sup&gt;&amp;nbsp;m&lt;sup&gt;2&lt;/sup&gt; and contain 11&amp;ndash;72 Mg of aboveground carbon, based on the 90% probability of occurrence. Our study illustrates the synergistic effect of combining field and remote sensing data for understanding the distribution and biomass of biocrusts, a foundational community in the carbon balance of this region. Extreme weather events and changing climate conditions in this region, especially those influencing snow accumulation and persistence, could have significant effects on the future distribution and abundance of biocrusts and therefore soil organic carbon storage in the McMurdo Dry Valleys.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">7</style></issue></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Power, Sarah N.</style></author><author><style face="normal" font="default" size="100%">Salvatore, Mark R.</style></author><author><style face="normal" font="default" size="100%">Eric R. Sokol</style></author><author><style face="normal" font="default" size="100%">Lee F. Stanish</style></author><author><style face="normal" font="default" size="100%">Borges, Schuyler R.</style></author><author><style face="normal" font="default" size="100%">Byron Adams</style></author><author><style face="normal" font="default" size="100%">John E. Barrett</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Remotely characterizing photosynthetic biocrust in snowpack-fed microhabitats of Taylor Valley, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">Science of Remote Sensing</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Antarctica</style></keyword><keyword><style  face="normal" font="default" size="100%">biocrust</style></keyword><keyword><style  face="normal" font="default" size="100%">carbon</style></keyword><keyword><style  face="normal" font="default" size="100%">reflectance spectroscopy</style></keyword><keyword><style  face="normal" font="default" size="100%">snow</style></keyword><keyword><style  face="normal" font="default" size="100%">soil ecology</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2024</style></year><pub-dates><date><style  face="normal" font="default" size="100%">02/2024</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://www.sciencedirect.com/science/article/pii/S266601722400004X</style></url></web-urls></urls><pages><style face="normal" font="default" size="100%">100120</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Microbial communities are the primary drivers of carbon cycling in the McMurdo Dry Valleys of Antarctica. Dense microbial mats, consisting mainly of photosynthetic cyanobacteria, occupy aquatic areas associated with streams and lakes. Other microbial communities also occur at lower densities as patchy surface biological soil crusts (hereafter, biocrusts) across the terrestrial landscape. Multispectral satellite data have been used to model microbial mat abundance in high-density areas like stream and lake margins, but no previous studies have investigated the lower detection limits of biocrusts. Here, we describe remote sensing and field-based survey and sampling approaches to study the detectability and distribution of biocrusts in the McMurdo Dry Valleys. Using a combination of multi- and hyperspectral tools and spectral linear unmixing, we modeled the abundances of biocrust in eastern Taylor Valley. Our spectral approaches can detect low masses of biocrust material in laboratory microcosms down to biocrust concentrations of 1% by mass. These techniques also distinguish the spectra of biocrust from both surface rock and mineral signatures from orbit. We found that biocrusts are present throughout the soils of eastern Taylor Valley and are associated with diverse underlying soil communities. The densest biocrust communities identified in this study had total organic carbon 5x greater than the content of typical arid soils. The most productive biocrusts were located downslope of melting snowpacks in unique soil ecosystems that are distinct from the surrounding arid landscape. There are similarities between the snowpack and stream sediment communities (high diversity of soil invertebrates) as well as their ecosystem properties (e.g., persistence of liquid water, high transfer of available nutrients, lower salinity from flushing) compared to the typical arid terrestrial ecosystem of the dry valleys. Our approach extends the capability of orbital remote sensing of photosynthetic communities out of the aquatic margins and into the drier soils which comprise most of this landscape. This interdisciplinary work is critical for measuring and monitoring terrestrial carbon stocks and predicting future ecosystem dynamics in this currently water-limited but increasingly dynamic Antarctic landscape, which is particularly climate-sensitive and difficult to access.&lt;/p&gt;</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Risteca, Paul J.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">John E. Barrett</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Influence of landscape-variation in geochemistry on taxonomic and functional composition of microbial mat communities in the McMurdo Dry Valleys, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">Biological Sciences</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">carbon</style></keyword><keyword><style  face="normal" font="default" size="100%">microbial community</style></keyword><keyword><style  face="normal" font="default" size="100%">microbial mat</style></keyword><keyword><style  face="normal" font="default" size="100%">nitrogen</style></keyword><keyword><style  face="normal" font="default" size="100%">phosphorus</style></keyword><keyword><style  face="normal" font="default" size="100%">polar desert</style></keyword><keyword><style  face="normal" font="default" size="100%">soil</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2023</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://hdl.handle.net/10919/115384</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">Virginia Tech</style></publisher><pub-location><style face="normal" font="default" size="100%">Blacksburg, VA</style></pub-location><volume><style face="normal" font="default" size="100%">M.S.</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Microbial communities play critical roles in biogeochemical cycles of aquatic and terrestrial ecosystems, but studies of soil microbial communities have been limited by the diversity and complexity found in most ecosystems. Here we report on work investigating the functional diversity of microbial mat and underlying soil communities in the McMurdo Dry Valleys of Antarctica across a gradient of phosphorus availability on glacial tills of distinct age and mineral composition in Taylor Valley, Antarctica. Microbial mat and soil DNA were extracted and sequenced on an Illumina NextSeq500 in a 150 bp paired end format. Raw sequences were uploaded to the MG-RAST server for processing and annotation. Community taxonomic and functional annotation were determined using the RefSeq and SEED Subsystem databases, respectively. The results revealed significant variation in microbial mat community taxonomic composition between the two tills, strongly associated with visual assessment of mat morphology, e.g., &amp;quot;black&amp;quot; and &amp;quot;orange&amp;quot; mats, and soil N:P ratios. The underlying soil microbial communities did not exhibit significant differences in diversity between the two tills, but community composition varied significantly across gradients of soil chemistry, particularly extractable-phosphate content even within tills. The relative abundance of biogeochemistry-relevant pathways determined from the SEED database varied amongst soil microbial communities between the two tills. For example, microbial mat communities exhibited significant variation in the relative abundance of key nitrogen and phosphorus metabolism associated genes strongly associated with the underlying soil N:P. These results suggest that spatial variation in geochemistry influences the distribution and activity of microbial mats, but that the microbial mats themselves also exert a significant homogenizing effect on the underlying soil communities and some of the key biogeochemical processes they facilitate.&lt;/p&gt;</style></abstract><work-type><style face="normal" font="default" size="100%">masters</style></work-type></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Koch, J.</style></author><author><style face="normal" font="default" size="100%">Diane M. McKnight</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Hydrologic and biogeochemical implications of flooding in two catchments underlain by continuous permafrost</style></title><secondary-title><style face="normal" font="default" size="100%">Department of Environmental Studies</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">carbon</style></keyword><keyword><style  face="normal" font="default" size="100%">catchments</style></keyword><keyword><style  face="normal" font="default" size="100%">earth sciences</style></keyword><keyword><style  face="normal" font="default" size="100%">flooding</style></keyword><keyword><style  face="normal" font="default" size="100%">nitrogen</style></keyword><keyword><style  face="normal" font="default" size="100%">permafrost</style></keyword><keyword><style  face="normal" font="default" size="100%">surface-groundwater interactions</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2010</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2010</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://search.proquest.com/docview/839008865</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">University of Colorado</style></publisher><pub-location><style face="normal" font="default" size="100%">Boulder, CO</style></pub-location><volume><style face="normal" font="default" size="100%">Ph.D.</style></volume><pages><style face="normal" font="default" size="100%">206</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Flooding is a critical driver of ecosystem productivity. By rapidly increasing stream stage and velocity, floods mix water and solutes from the stream, hyporheic zone, and floodplains/riparian areas. Such mixing may spur biogeochemical activity. In catchments underlain by permafrost, flooding is more common due to both the potential for rapid ice melting and minimal storage potential in frozen soils. High latitude environments are often underlain by permafrost and are also areas of biogeochemical interest, due to large stores of carbon (C) and nitrogen (N), and the potential for rapid cycling. The increased complexity in groundwater/surface water hydrology during floods requires rigorous hydrologic analysis before biogeochemical trends can be correctly interpreted. This research aims to accurately quantify the hydrology and biogeochemical cycling of C and N in two high-latitude catchments utilizing stream tracer additions, synoptic sampling, and surface water (sw), groundwater (gw), and coupled sw/gw flow models.&lt;/p&gt;&lt;p&gt;Two catchments, in Alaska and Antarctica represent very different ecosystems, both characterized by continuous permafrost and shallow aquifers. In Antarctica, coupled surface water/groundwater flow modeling and tracer additions identify sources of DOC (dissolved organic carbon) and locations of denitrification. Mass balance calculations identify heightened water/sediment interactions at high flows, and increased C and N uptake when solutes return to the stream during low flows. In Alaska, discharge correlates to DOC and nitrate concentrations, indicating leaching and flushing of organic material from the hillslope during high discharge, with a greater potential for microbial processing of this organic material during low flows. Multiple tracer additions demonstrate a seasonal trend, with the greatest C and N uptake early in the summer, potentially related to shallower flowpaths.&lt;/p&gt;&lt;p&gt;Differences between discharge, flooding, and C and N cycling in these two catchments indicate the importance of stream size and morphology. Using tracer dilution and major ion and uranium isotope chemistry, we identify preferential flow near and beneath the stream, indicating erosion of the stream bed via soil piping and thermokarsting. We propose that channel evolution will lead to decreased stream/catchment interactions and subsequently decreased C and N uptake potential in these high-latitude catchments.&lt;/p&gt;</style></abstract><work-type><style face="normal" font="default" size="100%">doctoral</style></work-type></record></records></xml>