Department of Geosciences and Geography, University of Helsinki, Helsinki, FI-00014, Finland.
Glob Chang Biol. 2013 Oct;19(10):2965-75. doi: 10.1111/gcb.12286. Epub 2013 Aug 13.
Shifts in precipitation regimes are an inherent component of climate change, but in low-energy systems are often assumed to be less important than changes in temperature. Because soil moisture is the hydrological variable most proximally linked to plant performance during the growing season in arctic-alpine habitats, it may offer the most useful perspective on the influence of changes in precipitation on vegetation. Here we quantify the influence of soil moisture for multiple vegetation properties at fine spatial scales, to determine the potential importance of soil moisture under changing climatic conditions. A fine-scale data set, comprising vascular species cover and field-quantified ecologically relevant environmental parameters, was analysed to determine the influence of soil moisture relative to other key abiotic predictors. Soil moisture was strongly related to community composition, species richness and the occurrence patterns of individual species, having a similar or greater influence than soil temperature, pH and solar radiation. Soil moisture varied considerably over short distances, and this fine-scale heterogeneity may contribute to offsetting the ecological impacts of changes in precipitation for species not limited to extreme soil moisture conditions. In conclusion, soil moisture is a key driver of vegetation properties, both at the species and community level, even in this low-energy system. Soil moisture conditions represent an important mechanism through which changing climatic conditions impact vegetation, and advancing our predictive capability will therefore require a better understanding of how soil moisture mediates the effects of climate change on biota.
降水格局的变化是气候变化的固有组成部分，但在低能量系统中，通常被认为不如温度变化重要。由于土壤湿度是在北极高山生境中与植物生长季节表现最接近的水文变量，因此它可能为降水变化对植被的影响提供最有用的视角。在这里，我们在精细的空间尺度上量化了土壤湿度对多种植被特性的影响，以确定在不断变化的气候条件下土壤湿度的潜在重要性。一个精细尺度的数据集中包含了血管物种的覆盖范围和现场量化的生态相关环境参数，用于分析以确定土壤湿度相对于其他关键非生物预测因子的影响。土壤湿度与群落组成、物种丰富度以及个别物种的出现模式密切相关，其影响与土壤温度、pH 值和太阳辐射相似或更大。土壤湿度在短距离内变化很大，这种精细尺度的异质性可能有助于抵消降水变化对非极端土壤湿度条件物种的生态影响。总之，即使在这个低能量系统中，土壤湿度也是植被特性（包括物种和群落水平）的关键驱动因素。土壤湿度条件代表了气候变化影响植被的一个重要机制，因此，要提高我们的预测能力，就需要更好地了解土壤湿度如何调节气候变化对生物群的影响。
