长期施加N、P肥对高寒草甸小型土壤节肢动物群落的影响

Effects of long⁃term N and P additions on the soil microarthropod communities in alpine meadows

为查明长期施肥对高寒草甸小型土壤节肢动物群落影响,2012年5月下旬在西南民族大学青藏高原畜牧业高科技研究基地内用随机区组方式设置施N、P和NP混施三种处理实验样地,每种施肥处理分别设置10 g/m^(2)、20 g/m^(2)和30 g/m^(2)三个施肥梯度,以不施肥的高寒草甸为对照样地。2017年8月对各样地内的小型土壤节肢动物、植物群落和土壤理化性质进行调查。结果表明:(1)施肥可以明显改变高寒草甸小型土壤节肢动物的群落组成结构,其中NP混施比单施N、P肥更能有效增加螨类和昆虫的类群数;(2)N、P、NP三种施肥种类的小型土壤节肢动物群落个体密度、类群数和Shannon多样性指数均显著增加(P<0.05),且当施肥量为20 g/m^(2)时,小型土壤节肢动物群落的个体密度、类群数和Shannon多样性指数均达到最大;(3)小型土壤节肢动物群落的个体密度、类群数和Shannon多样性指数均与全磷含量呈显著正相关(P<0.05)。研究表明,在高寒草甸长期施加氮、磷肥,尤其是氮磷混施,不仅能够明显改变小型土壤节肢动物群落组成结构,还能显著提高群落密度和多样性,建议按照20 g/m^(2)的总量对高寒草甸进行氮磷等量混施,以提高小型土壤节肢动物群落多样性及其生态功能。

The objective of this study was to examine the effects of long⁃term N and P addition on soil microarthropod communities in alpine meadows.Three addition treatments of N fertilizer(N),P fertilizer(P)and a NP mixed fertilizer(NP)were set up in Hongyuan County,northwest Sichuan,in late May 2012.Each treatment included three fertilization gradients of 10 g/m^(2)(N_(10),P_(10) and NP_(10)),20 g/m^(2)(N_(20),P_(20) and NP_(20)),and 30 g/m^(2)(N_(30),P_(30) and NP_(30))with six replication plots in size of 3 m×3 m.Another six plots of alpine meadow without N and P addition were used as control treatments(CK).Investigations were conducted on the soil microarthropods and environmental factors in each plot in August 2017.Soil microarthropods were extracted from the soil samples for 48 h at 38℃using the Tullgren method in the laboratory.The results showed that(1)the taxonomic composition structure of soil microarthropod communities was markedly influenced by N,P and NP additions,and the taxonomic richness of mites and insects were increased more significantly by NP mixed additions than N or P addition.(2)The individual density,taxonomic richness and Shannon diversity index of soil microarthropod communities increased significantly in the treatments of N,P and NP additions(P<0.05),and reached to maximum values at the fertilization gradient of 20 g/m^(2).(3)The individual density,taxonomic richness and Shannon diversity index significantly and positively correlated with soil total P(P<0.05).The results demonstrated that additions of N,P,especially NP,changed the taxonomic composition structure,and increased the individual density and diversity of soil microarthropod communities in alpine meadows on Qinghai⁃Tibet Plateau.We recommended to add the N and P equal mixed fertilizer to alpine meadows at total amount of 20 g/m^(2),to promote the soil microarthropod diversity and ecological functions.