海拔梯度变化对中亚热带黄山松土壤微生物生物量和群落结构的影响

全球变暖对陆地生态系统造成一系列生态问题,使这些问题将随着全球平均气温的升高而进一步加剧。海拔梯度变化是研究气候变暖对陆地生态系统影响的一种重要手段。目前为止利用海拔梯度对微生物影响的研究尚未定论,其主要原因是忽略了植被类型的影响。因此,以中亚热带戴云山的3个海拔(1300、1450、1600 m)的黄山松(Pinus taiwanensis)林为研究对象,探究沿海拔梯度的变化,森林土壤微生物生物量和微生物群落结构的响应变化。结果表明:土壤碳氮磷养分(SOC、TN、TP)、微生物生物量氮(MBN)、微生物生物量磷(MBP)和丛枝菌根真菌(AMF)、革兰氏阴性菌(GN)、真菌(Fungi)、总磷脂脂肪酸(T_(PLFA)),细菌∶真菌(F∶B)均随海拔升高显著下降,而革兰氏阳性菌∶革兰氏阴性菌(GP∶GN)随海拔升高呈相反的趋势。冗余分析(RDA)表明,温度(T)和可溶性有机氮(DON)是影响微生物群落结构的最重要的环境因子。研究表明:与1600 m海拔相比,1300 m海拔温度较高,土壤有机质矿化作用较强,土壤速效养分及微生物生物量随之增加,从而提高(Fungi)、细菌(Bacteria)等。因此,未来气候变暖将通过改变土壤碳氮磷养分来影响本区域微生物群落组成结构。这对进一步深入了解气候变化对山地生态系统土壤养分循环过程具有重要意义。

Effect of different altitudes on soil microbial biomass and community structure of Pinus taiwanensis forest in mid-subtropical zone

Global warming has caused a series of ecological issues in terrestrial ecosystems, which will be further aggravated by increasing global average temperatures. Changes in altitude gradients are an important aspect of studying the effects of climate warming on terrestrial ecosystems. Currently, studies on the effect of altitude gradient on microorganisms have not yielded conclusive results mainly because the influence of vegetation types has not been considered. Therefore, in this study, Pinus taiwanensis at 1300, 1450, and 1600 m in the mid-subtropical Daiyun Mountain were used to study changes in soil microbial biomass and community structure at different altitudes. The results showed that soil total carbon, total nitrogen, total phosphorus, microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), arbuscular mycorrhizal fungi (AMF), gram-negative fungi (GN), fungi, total phospholipid fatty acid (T_PLFA), and bacteria:fungi (F:B) ratio all decreased significantly with altitude. However, the gram-positive bacteria:gram-negative bacteria (GP:GN) ratio increased significantly with elevation. Redundancy analysis (RDA) showed that the temperature (T) and dissolved organic nitrogen (DON) content were the most important environmental factors that determined the soil microbial community structure. Studies have shown that compared with 1600 m altitude, the temperature at 1300 m altitude was higher, which promoted the mineralization of soil organic matter, and increased the availability of nutrients and number of microbial biomass in the soil, thereby increasing microbial biomass such as fungi and bacteria. Therefore, future climate warming will likely affect the composition of microbial communities in the region by changing the soil carbon, nitrogen, and phosphorus nutrient contents. These results are of great importance to further understand the effect of climate change on soil nutrient cycling in mountain ecosystems.