青藏高原高寒沼泽化草甸群落生物量及地下CNP对积雪增加的响应

Responses of plant community biomass and below-ground CNP stocks to snow addition in alpine swamp meadow on the Tibetan Plateau

以青藏高原多年冻土区高寒沼泽化草甸为研究对象,采用雪栅栏诱导方式模拟积雪厚度增加,结合植物地上、地下根系以及土壤养分变化,分析了高寒沼泽化草甸对积雪厚度增加的响应。结果表明:积雪厚度增加后,0~20cm浅层土壤温度和水分含量增加;植物群落高度和土壤表层0~10cm根系生物量显著增加,植物群落组成和地上生物量没有变化;地下0~20cm土壤碳(C)、氮(N)、磷(P)总储量降低,根系中C、N、P储量增加;土壤表层0~10cm总N∶P比显著增加,但是有效磷含量在0~10cm和10~20cm土层均显著增加。可见,积雪厚度增加并不影响沼泽化草甸植物群落的组成和地上生物量,仅增加植被高度;增加土壤表层总N∶P比意味着积雪厚度增加可能会减轻沼泽化草甸土壤中氮限制,从而减缓沼泽化草甸的氮匮乏状况。结论可为高寒生态系统响应积雪变化研究提供样地尺度的观测数据,并为冰冻圈生态系统应对未来气候变化的模型估算提供数据支撑。

In this study,snow fence was employed to simulate artificial snow addition in an alpine swamp of permafrost region on the Tibetan Plateau. We aimed to investigate the responses of alpine swamp ecosystem to snow addition. Our results showed that:Increased snow would increase both soil moisture and temperature at the depth of 0~20 cm;Increased snow would increase vegetation height and root biomass at depth of 0~10 cm;Increased snow would decrease below-ground pools in total carbon(C),total nitrogen(N)and total phosphorus(P)at the depth of 0~20 cm,although the C,N,P pools had increased in the roots;Increased snow also increased soil total N:P ratio with increasing available phosphorus concentration at the depth of 0~10 cm and 10~20 cm. Our results suggested that short-term snow addition had no effected community composition and above-ground biomass,but significantly increased vegetation height. Moreover,increased N:P ratio in the soil surface had indicated that snow addition could alleviate N limitation in the study region,thereby relieve the soil N deficiency for plant growth in this area. These findings provide observation data at the plot-scale for alpine ecosystem under snow change,as well as a dataset for modeling permafrost ecosystem under future climate change.