SEV-LTER Mean - Variance Experiment Plains Grassland Soil Moisture and Temperature

We designed novel field experimental infrastructure to resolve the relative importance of changes in the climate mean and variance in regulating the structure and function of dryland populations, communities, and ecosystem processes. The Mean - Variance Experiment (MVE) adds three novel elements to prior designs that have manipulated interannual variance in climate in the field (Gherardi & Sala, 2013) by (i) determining interactive effects of mean and variance with a factorial design that crosses reduced mean with increased variance, (ii) studying multiple dryland biomes to compare their susceptibility to transition under interactive climate drivers, and (iii) adding stochasticity to our treatments to permit the antecedent effects that occur under natural climate variability. This new infrastructure enables direct experimental tests of the hypothesis that interactions between the mean and variance of precipitation will have larger ecological impacts than either the mean or variance in precipitation alone. A subset of plots have soil moisture and temperature sensors to evaluate treatment effectiveness by addressing, How do MVE manipulations alter the mean and variance in soil moisture and temperature? And How does micro-environmental variation among plots influence how treatments alter soil moisture profiles over three soil depths? This data package includes sensor data from the Mean x Variance experiment in the Plains grassland ecosystem at the Sevilleta National Wildlife Refuge, Socorro, NM, which is dominated by the grass species Bouteloua gracilis (blue grama).

我们构建了一套全新的野外实验基础设施，旨在厘清气候均值与方差的变化在调控旱地种群、群落及生态系统过程的结构与功能时所发挥的相对重要性。本研究的均值-方差实验（Mean-Variance Experiment, MVE）在既往针对野外气候年际方差开展调控的实验设计（Gherardi & Sala, 2013）基础上，新增三项创新要素：其一，采用析因设计探究气候均值与方差的交互效应，将降低后的气候均值与升高后的气候方差进行交叉组合；其二，针对多个旱地生物群系展开研究，以对比它们在交互气候驱动因子作用下发生转变的易感性；其三，为实验处理引入随机性，以还原自然气候变率下存在的前期遗留效应。这套新型实验基础设施可直接验证下述假说：降水均值与降水方差之间的交互作用，其生态影响将大于单独改变降水均值或单独调控降水方差所产生的生态效应。部分样地配备了土壤湿度与温度传感器，用于评估实验处理的有效性，具体围绕两个科学问题展开：一是均值-方差实验的操控手段如何改变土壤湿度与温度的均值与方差？二是样地间的微环境差异如何影响实验处理在三个土壤深度上对土壤湿度剖面的改变作用？本数据集包含位于美国新墨西哥州索科罗市塞维利亚塔国家野生动物保护区的平原草地生态系统中开展的均值×方差实验的传感器监测数据，该草地的优势草本物种为格兰马草（Bouteloua gracilis, blue grama）。