@article {4942, title = {The distribution of surface soil moisture over space and time in eastern Taylor Valley, Antarctica}, journal = {Remote Sensing}, volume = {15}, year = {2023}, month = {06/2023}, pages = {3170}, abstract = {

Available soil moisture is thought to be the limiting factor for most ecosystem processes in the cold polar desert of the McMurdo Dry Valleys (MDVs) of Antarctica. Previous studies have shown that microfauna throughout the MDVs are capable of biological activity when sufficient soil moisture is available (~2\–10\% gravimetric water content), but few studies have attempted to quantify the distribution, abundance, and frequency of soil moisture on scales beyond that of traditional field work or local field investigations. In this study, we present our work to quantify the soil moisture content of soils throughout the Fryxell basin using multispectral satellite remote sensing techniques. Our efforts demonstrate that ecologically relevant abundances of liquid water are common across the landscape throughout the austral summer. On average, the Fryxell basin of Taylor Valley is modeled as containing 1.5 \± 0.5\% gravimetric water content (GWC) across its non-fluvial landscape with ~23\% of the landscape experiencing an average GWC \> 2\% throughout the study period, which is the observed limit of soil nematode activity. These results indicate that liquid water in the soils of the MDVs may be more abundant than previously thought, and that the distribution and availability of liquid water is dependent on both soil properties and the distribution of water sources. These results can also help to identify ecological hotspots in the harsh polar Antarctic environment and serve as a baseline for detecting future changes in the soil hydrological regime.

}, keywords = {LTER-MCM, Dry valleys, ecology, hydrology, remote sensing, soil moisture}, doi = {10.3390/rs15123170}, url = {https://www.mdpi.com/2072-4292/15/12/3170}, author = {Salvatore, Mark R. and Barrett, John E. and Fackrell, Laura E. and Sokol, Eric R. and Levy, Joseph S. and Kuentz, Lily C. and Gooseff, Michael N. and Adams, Byron J. and Power, Sarah N. and Knightly, J. Paul and Matul, Haley M. and Szutu, Brian and Doran, Peter T.} } @article {4945, title = {Timing and duration of ephemeral Antarctic water tracks and wetlands using high temporal{\textendash}resolution satellite imagery, high spatial{\textendash}resolution satellite imagery, and ground-based sensors in the McMurdo Dry Valleys}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {54}, year = {2022}, month = {12/2022}, pages = {538 - 561}, abstract = {

Antarctic water tracks and ephemeral wetlands are a primary location for biogeochemical soil processes driving cold desert soil formation. Though the spatial extent of water tracks and wetted soils has been mapped in the McMurdo Dry Valleys (MDV) on the basis of mapping darkened pixels in high-resolution commercial satellite imagery, the timescale over which water tracks and wetlands form and the duration of these biogeochemically active environments remain unknown. Here, we determine the start date and end dates and the duration of wetted soils at ten sites located across the MDV using a combination of in situ soil sensors and two complementary remote imaging platforms (Planet and WorldView) to understand the hydroclimatic processes that drive water track and wetland formation. Our remote sensing employs a terrain correction workflow that removes the contribution of differential direct illumination and small-scale shadowing on pixel brightness, reducing false positives (soils identified as wetted when in fact they are shadowed or darkened as a consequence of high phase angle). Our findings extend the water track and wetland hydroperiod by over a month, showing darkening occurring from November to March, suggesting hydrological contributions from ground ice thaw, snowmelt, and salt deliquescence and soil brine growth.

}, keywords = {LTER-MCM, Antarctica, hydroperiod, remote sensing, water track, wetland}, issn = {1523-0430}, doi = {10.1080/15230430.2022.2123858}, url = {https://www.tandfonline.com/doi/full/10.1080/15230430.2022.2123858}, author = {Kuentz, Lily C. and Joseph S. Levy and Salvatore, Mark R.} } @article {4691, title = {Episodic basin-scale soil moisture anomalies associated with high relative humidity events in the McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Science}, year = {2021}, month = {08/2021}, pages = {1-15}, abstract = {

Outside of hydrologically wetted active layer soils and humidity-sensitive soil brines, low soil moisture is a limiting factor controlling biogeochemical processes in the McMurdo Dry Valleys. But anecdotal field observations suggest that episodic wetting and darkening of surface soils in the absence of snowmelt occurs during high humidity conditions. Here, I analyse long-term meteorological station data to determine whether soil-darkening episodes are present in the instrumental record and whether they are, in fact, correlated with relative humidity. A strong linear correlation is found between relative humidity and soil reflectance at the Lake Bonney long-term autonomous weather station. Soil reflectance is found to decrease annually by a median of 27.7\% in response to high humidity conditions. This magnitude of darkening is consistent with soil moisture rising from typical background values of \< 0.5 wt.\% to 2\–3 wt.\%, suggesting that regional atmospheric processes may result in widespread soil moisture generation in otherwise dry surface soils. Temperature and relative humidity conditions under which darkening is observed occur for hundreds of hours per year, but are dominated by episodes occurring between midnight and 07h00 local time, suggesting that wetting events may be common, but are not widely observed during typical diel science operations.

}, keywords = {LTER-MCM, deliquescence, hydrology, microclimate, micrometeorology, pedology, remote sensing}, issn = {0954-1020}, doi = {10.1017/S0954102021000341}, url = {https://www.cambridge.org/core/product/identifier/S0954102021000341/type/journal_article}, author = {Joseph S. Levy} } @article {4516, title = {Estimating microbial mat biomass in the McMurdo Dry Valleys, Antarctica using satellite imagery and ground surveys}, journal = {Polar Biology}, year = {2020}, month = {09/2020}, abstract = {

Cyanobacterial mat communities are the main drivers of primary productivity in the McMurdo Dry Valleys, Antarctica. These microbial communities form laminar mats on desert pavement surfaces adjacent to glacial meltwater streams, ponds, and lakes. The low-density nature of these communities and their patchy distribution make assessments of distribution, biomass, and productivity challenging. We used satellite imagery coupled with in situ surveying, imaging, and sampling to systematically estimate microbial mat biomass in selected wetland regions in Taylor Valley, Antarctica. On January 19th, 2018, the WorldView-2 multispectral satellite acquired an image of our study areas, where we surveyed and sampled seven 100 m2 plots of microbial mats for percent ground cover, ash-free dry mass (AFDM), and pigment content (chlorophyll-a, carotenoids, and scytonemin). Multispectral analyses revealed spectral signatures consistent with photosynthetic activity (relatively strong reflection at near-infrared wavelengths and relatively strong absorption at visible wavelengths), with average normalized difference vegetation index (NDVI) values of 0.09 to 0.28. Strong correlations of microbial mat ground cover (R2\ =\ 0.84), biomass (R2\ =\ 0.74), chlorophyll-a content (R2\ =\ 0.65), and scytonemin content (R2\ =\ 0.98) with logit transformed NDVI values demonstrate that satellite imagery can detect both the presence of microbial mats and their key biological properties. Using the NDVI\—biomass correlation we developed, we estimate carbon (C) stocks of 21,715 kg (14.7 g C m\−2) in the Canada Glacier Antarctic Specially Protected Area, with an upper and lower limit of 74,871 and 6312 kg of C, respectively.

}, keywords = {LTER-MCM, Antarctica, microbial mat, multispectral imagery, NDVI, Nostocales, remote sensing}, doi = {10.1007/s00300-020-02742-y}, url = {https://link.springer.com/article/10.1007\%2Fs00300-020-02742-y}, author = {Power, Sarah N. and Salvatore, Mark R. and Eric R. Sokol and Lee F. Stanish and John E. Barrett} } @article {4449, title = {Remote characterization of photosynthetic communities in the Fryxell basin of Taylor Valley, Antarctica}, journal = {Antarctic Science}, year = {2020}, month = {03/2020}, abstract = {

We investigate the spatial distribution, spectral properties and temporal variability of primary producers (e.g. communities of microbial mats and mosses) throughout the Fryxell basin of Taylor Valley, Antarctica, using high-resolution multispectral remote-sensing data. Our results suggest that photosynthetic communities can be readily detected throughout the Fryxell basin based on their unique near-infrared spectral signatures. Observed intra- and inter-annual variability in spectral signatures are consistent with short-term variations in mat distribution, hydration and photosynthetic activity. Spectral unmixing is also implemented in order to estimate mat abundance, with the most densely vegetated regions observed from orbit correlating spatially with some of the most productive regions of the Fryxell basin. Our work establishes remote sensing as a valuable tool in the study of these ecological communities in the McMurdo Dry Valleys and demonstrates how future scientific investigations and the management of specially protected areas could benefit from these tools and techniques.

}, keywords = {LTER-MCM, ecology, hydrology, McMurdo Dry Valleys, microbiology, remote sensing, spectroscopy}, doi = {10.1017/S0954102020000176}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/remote-characterization-of-photosynthetic-communities-in-the-fryxell-basin-of-taylor-valley-antarctica/8576F6BB1BCFDCA8409F5EA96CA00C6F}, author = {Salvatore, Mark R. and Borges, Schuyler R. and John E. Barrett and Eric R. Sokol and Lee F. Stanish and Power, Sarah N. and Morin, Paul} }