Escolar Cristina, Maestre Fernando T, Rey Ana
Área de Biodiversidad y Conservación, Departamento de Biología y Geología, Física y Química Inorgánica, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, E-28933 Móstoles, Spain.
Department of Biogeography and Global Change, Museo de Ciencias Naturales, C.S.I.C., Serrano 115, 28006 Madrid, Spain.
Soil Biol Biochem. 2015 Jan 1;80:9-17. doi: 10.1016/j.soilbio.2014.09.019.
Soil surface communities composed of cyanobacteria, algae, mosses, liverworts, fungi, bacteria and lichens (biocrusts) largely affect soil respiration in dryland ecosystems. Climate change is expected to have large effects on biocrusts and associated ecosystem processes. However, few studies so far have experimentally assessed how expected changes in temperature and rainfall will affect soil respiration in biocrust-dominated ecosystems. We evaluated the impacts of biocrust development, increased air temperature and decreased precipitation on soil respiration dynamics during dry (2009) and wet (2010) years, and investigated the relative importance of soil temperature and moisture as environmental drivers of soil respiration, in a semiarid grassland from central Spain. Soil respiration rates were significantly lower in the dry than during the wet year, regardless of biocrust cover. Warming increased soil respiration rates, but this response was only significant in biocrust-dominated areas (> 50% biocrust cover). Warming also increased the temperature sensitivity (Q values) of soil respiration in biocrust-dominated areas, particularly during the wet year. The combination of warming and rainfall exclusion had similar effects in low biocrust cover areas. Our results highlight the importance of biocrusts as a modulator of soil respiration responses to both warming and rainfall exclusion, and indicate that they must be explicitly considered when evaluating soil respiration responses to climate change in drylands.
由蓝藻、藻类、苔藓、地钱、真菌、细菌和地衣组成的土壤表面群落（生物结皮）在很大程度上影响着旱地生态系统中的土壤呼吸。气候变化预计会对生物结皮及相关生态系统过程产生重大影响。然而，到目前为止，很少有研究通过实验评估预期的温度和降雨变化将如何影响以生物结皮为主的生态系统中的土壤呼吸。我们评估了生物结皮发育、气温升高和降水减少对西班牙中部半干旱草原干旱年份（2009年）和湿润年份（2010年）土壤呼吸动态的影响，并研究了土壤温度和湿度作为土壤呼吸环境驱动因素的相对重要性。无论生物结皮覆盖情况如何，干旱年份的土壤呼吸速率均显著低于湿润年份。升温增加了土壤呼吸速率，但这种响应仅在生物结皮主导的区域（生物结皮覆盖率>50%）显著。升温还增加了生物结皮主导区域土壤呼吸的温度敏感性（Q值），尤其是在湿润年份。在生物结皮覆盖率低的区域，升温和降雨排除的组合具有类似的影响。我们的结果突出了生物结皮作为土壤呼吸对升温和降雨排除响应的调节因子的重要性，并表明在评估旱地土壤呼吸对气候变化的响应时，必须明确考虑生物结皮。
