海拔梯度模拟气候变暖对高山森林土壤微生物生物量碳氮磷的影响

Effects of simulated climate warming on soil microbial biomass carbon, nitrogen and phosphorus of alpine forest

土壤微生物生物量在陆地生态系统碳氮磷循环中起着重要作用,是森林生态系统物质循环和能量流动的重要组成部分.以青藏高原东缘的川西高山森林土壤为研究对象,将暗针叶林土壤(3 900 m)沿海拔上移到高山林线(4 000 m),模拟气候变暖对土壤有机层和矿质土壤层微生物生物量的影响.结果表明,海拔上升导致土壤温度升高,但增温并未对雪被期高山森林土壤微生物生物量及其比值产生显著影响.方差分析表明,土壤层次对微生物生物量碳(MBC)、微生物生物量氮(MBN)、微生物生物量磷(MBP)影响都极显著(P<0.01),对MBC/MBN、MBN/MBP影响显著(P<0.05),雪被不同时期对MBN、MBP、MBC/MBN、MBC/MBP、MBN/MBP影响极显著(P<0.01);相关分析表明,MBC、MBN、MBP与土壤温度和土壤湿度呈现显著正相关(P<0.05);MBN、MBP与冻融次数之间呈现极显著正相关(P<0.01);MBC/MBN、MBN/MBP、MBC/MBP与温度和雪被厚度呈现极显著正相关(P<0.01).从长远来看,未来气候变暖对高山森林生态系统碳氮磷平衡的影响将取决于土壤微生物生物量和群落结构对这些环境因子的响应和反馈.

As a main component of the terrestrial ecosystem, soil microorganisms play an important role in its carbon, nitrogen and phosphorus cycle and energy flow. The alpine forest soil samples were taken in the alpine forest at 3 900 m and then moved to the timberline at 4 000 m, to study with natural gradient experiment the effect of simulated warming on the soil microbial biomass of soil organic layer （OL） and mineral soil layer （ML） in snow-covered season. The results showed that simulated warming increased soil temperature, but did not have a significant impact on soil microbial biomass or its ratio. The variance analysis showed that soil layers significantly impacted soil microbial biomass carbon, nitrogen and phosphorus, MBC/MBN, MBN/MBP （P 〈 0.05）; snow had a significant impact on soil microbial biomass nitrogen and phosphorus, MBC/MBN, MBC/ MBP, MBN/MBP （P 〈 0.01）. The correlation analysis showed that soil microbial biomass carbon, nitrogen and phosphorus had significant correlations with soil moisture and temperature （P 〈 0.05）; soil microbial biomass nitrogen and phosphorus had significant correlations with freeze-thaw cycles （P 〈 0.01）; MBC/MBN, MBN/MBP, MBC/MBP had significant correlations with soil temperature and snow depth （P 〈 0.01）. In the long run, the carbon, nitrogen and phosphorus balance of alpine forest ecosystem will depend on the response of soil microbial biomass and community structure to the climate warming.