The Responses Of Soil Nematode To Warming And Precipitation Pattern Change In An Alpine Meadow On The Tibetan Plateau

In recent years,global temperature and precipitation pattern have changed significantly.Over the past 50 years,the average temperature of the Tibetan Plateau has increased by 0.2 ° C every 10 years,and this trend has further intensified since 2000.With the warming and precipitation pattern change,grassland degradation on alpine meadow ecosystems has become increasingly serious,which is a widespread concerned problem.Soil nematodes are important part of belowground biological communities.Soil nematodes are considered biological indicators for monitoring environmental disturbances because of playing a key role in regulating carbon and nutritional dynamics.In the context of global climate change,much research focused on how climate change influence on aboveground vegetation and soil microbial community,however,research on soil nematodes is still scarce.In this research,long-term field control experiments were used to investigate the effects of aboveground plant community,soil microbial community,as well as soil chemical properties on soil nematode community,which can provide direct evidence for the responses of soil nematodes to changes in warming and precipitation pattern in an alpine meadow of the Tibetan Plateau in the context of future global climate changes.This study was conducted at the Ministry of Education Field Scientific Observation and Research Station of Gannan Grassland Ecosystem(Azi).This study was conducted under two long-term control experimental platforms,including 1)warming and precipitation change experiment,and 2)warming and precipitation interannual variation experiment(began in May 2017).From August to September 2018,we sampled and analyzed plant community,soil nematode community,soil microbial community,and soil chemical properties under two experimental platforms.Nonmetric multidimensional scaling(NMDS)was used to analyze the changes of soil nematode community composition among experimental treatments.The relationships between biotic and abiotic factors and soil nematode community and different trophic groups was analyzed by Redundancy analysis(RDA).The results are mainly as follows:1)After the two-year warming treatment,the abundance,richness,diversity index,trophic groups,and community composition of soil nematodes did not respond significantly to the warming treatment,however,warming treatment significantly reduced the EI,and increased Channel Index(CI).2)Soil nematode abundance was significantly higher in the treatment of precipitation increase;the precipitation increase and decrease had no significant effect on soil nematode community composition.Precipitation increase and decrease significantly reduced Enrichment Index(EI),and precipitation decrease significantly increased Channel Index(CI).3)The interaction between warming precipitation increase or decrease caused significantly change soil nematode community composition,and reduced Maturity Index(MI)and Structure Index(SI),however significantly increased Basal Index(BI).Warming and precipitation increase treatment significantly reduced Enrichment Index(EI).4)In the experiment of warming and precipitation interannual variation,whether it was first to increase precipitation then decrease precipitation treatment,or first to decrease precipitation then increase precipitation treatment,soil nematodes had no significant changes.5)In the warming and precipitation interannual variation experiment,the interaction between warming and precipitation variation only affected soil nematode abundance and evenness as well as the cp-1 group,but had no significant effect on the trophic groups and the ecological function index.This study provides an important scientific basis for the research of the restoration of degraded grassland ecosystem,protection of soil biodiversity,and soil nutrient cycling in an alpine meadow ecosystem of the Tibetan Plateau.