Desert Microbial Activity in the Rhizosphere Oasis

在沙漠生态系统中，植物的生长和繁殖受到水供应的限制，但也受到氮和其他土壤养分的限制。土壤真菌和细菌负责将死亡物质中的养分回收到植物可以利用的形式，但水分利用率低可能会限制土壤微生物进行这种转化的能力。有趣的是，一些根深蒂固的沙漠植物的根部可以充当被动水分从潮湿的土层进入更浅、更干燥的土层的管道，在那里碎屑丰富，这一过程被称为水力再分配。这种水分进入干燥土壤的运动可能会刺激根部周围的微生物活动。这项研究项目将包括综合温室和实地研究，利用三齿艾草(普通鼠尾草)将水从美国西部景观中较湿的土层重新分配到较干燥的土层的能力。在温室实验中使用微生物传感器，以及在犹他州田间场地进行土壤、植物和微生物分析，将检验山艾根对水的水力再分配，以了解其促进土壤养分循环和养分有效性的能力。养分供应的增强反过来可能导致植物光合作用、生长和繁殖产量的提高，这些植物积极地重新分配水分。作为这项研究的配套，伍斯特生态馆将开发一个展览，提供几个主要信息，包括：1.土壤中有有益的微生物；2.根是双向的街道，既可以吸收水分，也可以释放水分。

In desert ecosystems, plant growth and reproduction are limited by water availability, but also by nitrogen and other soil nutrients. Soil fungi and bacteria are responsible for recycling nutrients from dead material into forms that plants can use, but low water availability can limit the ability of soil microbes to carry out such transformations. Interestingly, the roots of some deep-rooted desert plants can act as conduits for passive water movement from moist soil layers into shallow, drier layers where detritus is abundant, in a process called hydraulic redistribution. Microbial activity may be stimulated around roots by this movement of water into dry soil. This research project will include integrated greenhouse and field studies that take advantage of the ability of Artemisia tridentata (common sagebrush) to redistribute water from wetter to drier soil layers in Western U.S. landscapes. Using microbiosensors in greenhouse experiments, and soil, plant, and microbial assays in Utah field sites, hydraulic redistribution of water by sagebrush roots will be examined for its ability to promote soil nutrient cycling and nutrient availability. Enhanced nutrient availability may in turn lead to enhanced photosynthesis, growth, and reproductive yield of plants actively redistributing water. As a companion to the research, an exhibit will be developed at the Worcester Ecotarium that provides several primary messages, including: 1. Soil is alive with beneficial microbes, and 2. Roots are two-way streets which can both take up and release water.