Área de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, Móstoles 28933, Spain.
Philos Trans R Soc Lond B Biol Sci. 2012 Nov 19;367(1606):3087-99. doi: 10.1098/rstb.2011.0344.
Biological soil crusts (BSCs) are key biotic components of dryland ecosystems worldwide that control many functional processes, including carbon and nitrogen cycling, soil stabilization and infiltration. Regardless of their ecological importance and prevalence in drylands, very few studies have explicitly evaluated how climate change will affect the structure and composition of BSCs, and the functioning of their constituents. Using a manipulative experiment conducted over 3 years in a semi-arid site from central Spain, we evaluated how the composition, structure and performance of lichen-dominated BSCs respond to a 2.4°C increase in temperature, and to an approximately 30 per cent reduction of total annual rainfall. In areas with well-developed BSCs, warming promoted a significant decrease in the richness and diversity of the whole BSC community. This was accompanied by important compositional changes, as the cover of lichens suffered a substantial decrease with warming (from 70 to 40% on average), while that of mosses increased slightly (from 0.3 to 7% on average). The physiological performance of the BSC community, evaluated using chlorophyll fluorescence, increased with warming during the first year of the experiment, but did not respond to rainfall reduction. Our results indicate that ongoing climate change will strongly affect the diversity and composition of BSC communities, as well as their recovery after disturbances. The expected changes in richness and composition under warming could reduce or even reverse the positive effects of BSCs on important soil processes. Thus, these changes are likely to promote an overall reduction in ecosystem processes that sustain and control nutrient cycling, soil stabilization and water dynamics.
生物土壤结皮（BSCs）是全球干旱生态系统的关键生物组成部分，控制着许多功能过程，包括碳和氮循环、土壤稳定和渗透。尽管它们在干旱地区具有重要的生态意义和普遍性，但很少有研究明确评估气候变化将如何影响 BSCs 的结构和组成，以及其组成部分的功能。本研究通过在西班牙中部半干旱地区进行的一项为期 3 年的操纵实验，评估了地衣主导的 BSCs 的组成、结构和性能如何响应温度升高 2.4°C 以及总年降雨量减少约 30%。在 BSCs 发育良好的地区，变暖促进了整个 BSC 群落丰富度和多样性的显著下降。这伴随着重要的组成变化，因为地衣的覆盖面积随着变暖而大幅减少（平均从 70%减少到 40%），而苔藓的覆盖面积略有增加（平均从 0.3%增加到 7%）。使用叶绿素荧光评估的 BSC 群落生理性能在实验的第一年随着变暖而增加，但对降雨量减少没有响应。我们的研究结果表明，正在进行的气候变化将强烈影响 BSC 群落的多样性和组成，以及它们在受到干扰后的恢复能力。在变暖条件下丰富度和组成的预期变化可能会减少甚至逆转 BSCs 对重要土壤过程的积极影响。因此，这些变化可能会导致维持和控制养分循环、土壤稳定和水动力的生态系统过程总体减少。
