Polygon Study: Variability in soil biogeochemistry and biodiversity

In the Antarctic Dry Valleys, soil polygons are prominent features of the landscape
and may be key units for scaling local ecological information to the greater region. We examined
polygon soils in each of the 3 basins of Taylor Valley, Antarctica. Our objectives were to characterize
variability in soil biogeochemistry and biodiversity at local to regional scales, and to test the
influence of soil properties upon invertebrate communities. We found that soil biogeochemical
properties and biodiversity vary over multiple spatial scales from fine (less than 10 m) to broad
(greater than 10 km) scales. Differences in biogeochemistry were most pronounced at broad
scales among the major lake basins of Taylor Valley corresponding to differences in geology
and microclimate, while variation in invertebrate biodiversity and abundance occurred at
landscape scales of 10-500 m, and within individual soil polygons. Variation in biogeochemistry
and invertebrate communities across these scales reflects the influence of physical processes
and landscape development over ecosystem structure in the dry valleys. The development of
soil polygons influences the spatial patterning of soil properties such as soil organic matter,
salinity, moisture, and invertebrate habitat suitability. Nematode abundance and life history data
indicate that polygon interiors are more suitable habitats than soils in the troughs at the edges
of polygons. These data suggest that physical processes (i.e. polygon development) and
biogeochemistry are an important influence on the spatial variability of biotic communities in
dry valley soil ecosystems.

南极干谷中，土壤多边形（soil polygons）是该区域显著的景观特征，亦是将局地生态信息外推至更大区域的关键单元。本研究针对南极泰勒谷（Taylor Valley）的3个湖盆分别开展了多边形土壤调查，研究目标在于刻画局地至区域尺度下土壤生物地球化学与生物多样性的变异特征，并探究土壤属性对无脊椎动物群落的调控作用。研究发现，土壤生物地球化学属性与生物多样性在多个空间尺度上存在变异，尺度范围涵盖细尺度（小于10米）至广尺度（大于10千米）。生物地球化学属性的差异在泰勒谷各主要湖盆的广尺度上最为显著，这与区域地质条件与微气候的差异高度契合；而无脊椎动物的生物多样性与丰度变异则出现在10-500米的景观尺度，以及单个土壤多边形内部。不同尺度下生物地球化学属性与无脊椎动物群落的变异，反映了干谷区域物理过程与景观演化对生态系统结构的调控效应。土壤多边形的发育过程会塑造土壤属性的空间格局，涉及土壤有机质、盐度、含水量及无脊椎动物栖息地适宜性等指标。线虫（nematode）丰度与生活史数据显示，土壤多边形内部相较于其边缘槽沟内的土壤，是更优质的栖息生境。上述研究数据表明，物理过程（即土壤多边形发育）与生物地球化学过程，是调控干谷土壤生态系统中生物群落空间变异的核心驱动因素。