<?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%">Kevin M. Geyer</style></author><author><style face="normal" font="default" size="100%">Cristina D. Takacs-Vesbach</style></author><author><style face="normal" font="default" size="100%">Michael N. Gooseff</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%">Primary productivity as a control over soil microbial diversity along environmental gradients in a polar desert ecosystem</style></title><secondary-title><style face="normal" font="default" size="100%">PeerJ</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2017</style></year><pub-dates><date><style  face="normal" font="default" size="100%">07/2017</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://peerj.com/articles/3377/</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">5</style></volume><pages><style face="normal" font="default" size="100%">e3377</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvP7627;&quot;&gt;Primary production is the fundamental source of energy to foodwebs and ecosystems, and is thus an important constraint on soil communities. This coupling is particularly evident in polar terrestrial ecosystems where biological diversity and activity is tightly constrained by edaphic gradients of productivity (e.g., soil moisture, organic carbon availability) and geochemical severity (e.g., pH, electrical conductivity). In the McMurdo Dry Valleys of Antarctica, environmental gradients determine numerous properties of soil communities and yet relatively few estimates of gross or net primary productivity (GPP, NPP) exist for this region. Here we describe a survey utilizing pulse amplitude modulation (PAM) fluorometry to estimate rates of GPP across a broad environmental gradient along with belowground microbial diversity and decomposition. PAM estimates of GPP ranged from an average of 0.27 &lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvPS7DA6;&quot;&gt;m&lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvP7627;&quot;&gt;mol O&lt;/span&gt;&lt;span style=&quot;font-size: 8pt; font-family: AdvP7627; vertical-align: -2pt;&quot;&gt;2&lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvP7627;&quot;&gt;/m&lt;/span&gt;&lt;span style=&quot;font-size: 8pt; font-family: AdvP7627; vertical-align: 5pt;&quot;&gt;2&lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvP7627;&quot;&gt;/s in the most arid soils to an average of 6.97 &lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvPS7DA6;&quot;&gt;m&lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvP7627;&quot;&gt;mol O&lt;/span&gt;&lt;span style=&quot;font-size: 8pt; font-family: AdvP7627; vertical-align: -2pt;&quot;&gt;2&lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvP7627;&quot;&gt;/m&lt;/span&gt;&lt;span style=&quot;font-size: 8pt; font-family: AdvP7627; vertical-align: 5pt;&quot;&gt;2&lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvP7627;&quot;&gt;/s in the most productive soils, the latter equivalent to 217 g C/m&lt;/span&gt;&lt;span style=&quot;font-size: 8pt; font-family: AdvP7627; vertical-align: 5pt;&quot;&gt;2&lt;/span&gt;&lt;span style=&quot;font-size: 11pt; font-family: AdvP7627;&quot;&gt;/y in annual NPP assuming a 60 day growing season. A diversity index of four carbon-acquiring enzyme activities also increased with soil productivity, suggesting that the diversity of organic substrates in mesic environments may be an additional driver of microbial diversity. Overall, soil productivity was a stronger predictor of microbial diversity and enzymatic activity than any estimate of geochemical severity. These results highlight the fundamental role of environmental gradients to control community diversity and the dynamics of ecosystem-scale carbon pools in arid systems.&amp;nbsp;&lt;/span&gt;&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">10</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%">David J. Van Horn</style></author><author><style face="normal" font="default" size="100%">Wolf, Caitlin R.</style></author><author><style face="normal" font="default" size="100%">Colman, Daniel R.</style></author><author><style face="normal" font="default" size="100%">Jiang, Xiaoben</style></author><author><style face="normal" font="default" size="100%">Tyler J. Kohler</style></author><author><style face="normal" font="default" size="100%">Diane M. McKnight</style></author><author><style face="normal" font="default" size="100%">Lee F. Stanish</style></author><author><style face="normal" font="default" size="100%">Yazzie, Terrill</style></author><author><style face="normal" font="default" size="100%">Cristina D. Takacs-Vesbach</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Patterns of bacterial biodiversity in the glacial meltwater streams of the McMurdo Dry Valleys, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">FEMS Microbiology Ecology</style></secondary-title><short-title><style face="normal" font="default" size="100%">FEMS Microbiology Ecology</style></short-title></titles><dates><year><style  face="normal" font="default" size="100%">2016</style></year><pub-dates><date><style  face="normal" font="default" size="100%">08/2016</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://femsec.oxfordjournals.org/lookup/doi/10.1093/femsec/fiw148</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">92</style></volume><pages><style face="normal" font="default" size="100%">fiw148</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 consortia dominate glacial meltwater streams from polar regions, including the McMurdo Dry Valleys (MDV), where they thrive under physiologically stressful conditions. In this study, we examined microbial mat types and sediments found in 12 hydrologically diverse streams to describe the community diversity and composition within and across sites. Sequencing of the 16S rRNA gene from 129 samples revealed &amp;sim;24 000 operational taxonomic units (&amp;lt;97% DNA similarity), making streams the most biodiverse habitat in the MDV. Principal coordinate analyses revealed significant but weak clustering by mat type across all streams (ANOSIM R-statistic = 0.28) but stronger clustering within streams (ANOSIM R-statistic from 0.28 to 0.94). Significant relationships (P &amp;lt; 0.05) were found between bacterial diversity and mat ash-free dry mass, suggesting that diversity is related to the hydrologic regimes of the various streams, which are predictive of mat biomass. However, correlations between stream chemistry and community members were weak, possibly reflecting the importance of internal processes and hydrologic conditions. Collectively, these results suggest that localized conditions dictate bacterial community composition of the same mat types and sediments from different streams, and while MDV streams are hotspots of biodiversity in an otherwise depauperate landscape, controls on community structure are complex and site specific.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">10</style></issue></record></records></xml>