| The objective of this study is to examine the effects of global warming on the community structure and diversity of soil organisms in an alpine meadow ecosystems.Twenty Open-topped chambers of 2 m(length)× 2 m(width)× 2 m(height)spacing not less than 5 m were randomly set up in Hongyuan County,northwest Sichuan,in late May 2009.Ten samples were surrounded by a numerical solar panel with a light transmittance of more than 90%,Which were used as OTC.And the other 10 samples are surrounded by steel mesh with pore size is 0.2 mm×0.2 mm,as controls.In August 2019,investigations were conducted on the epigeic arthropods,soil arthropods,soil nematodes and soil environmental factors in 20 plots to study the effects of long-term warming on the soil faunas.The main results were the followings:1.When the soil depth is 0-10 cm,long-term warmings significantly increased the soil temperature and carbon to nitrogen ratio,reduce soil moisture and organic matter content with controls(P<0.05);When the soil depth is 10-20 cm,long-term warmings significantly increased soil moisture and phosphorus content,the soil pH,organic matter content,total nitrogen content in the deep soil layer are significantly reduced(P<0.05).2.A total of 29524 epigeic arthropods were collected,which attached to 3 classes,22 orders,107 families and 124 taxonomic groups,Entomobrya was dominant groups.A total of 285 soil arthropods were collected,which attached to 4 classes,10 orders,39 families and 51 taxonomic groups;Folsomia and Galumnella were dominant groups.A total of 14029 soil nematodes were collected,which attached to 2 classes,7 orders,38 families and 80 taxonomic groups;the community abundance was 1073 individuals 100g-1 dry soil and no dominant groups.3.The Principal Component Analysis(PCA)results showed that there were significant differences in the community composition of epigeic arthropods,soil arthropods,and soil nematodes between the long-term warming and control plots;and the difference in the composition of soil arthropod and soil nematode communities becomes more obvious with the increase of soil depth.4.The community density and diversity of epigeic arthropods,soil arthropods and soil nematodes respond differently to long-term warming.Long-term warming has significantly reduced the taxonomic richness of epigeic arthropods and soil nematode communities,but the Shannon diversity index of epigeic arthropods has increased significantly(P<0.05).However,taxonomic richness,density,and Shannon index of soil arthropods and soil nematodes did not decrease significantly(P>0.05).5.Long-term warming significantly reduced the density of bacterivorous nematodes and fungivores nematodes,but had no significant effect on plant parasitic nematodes,predator-omnivorous nematodes.The study showed that long-term warming inhibited the function of soil microorganism decomposition pathways in the soil food web.6.The results of Principal Redundancy analysis(RDA)showed that the main factors affecting the composition of soil faunas are pH and ST.Relationships between soil nematodes and environmental factors showed that soil pH,soil moisture,available phosphorus content,total phosphorus content and organic matter content were the main factors affected the diversity of epigeic arthropods,soil arthropods,soil nematodes communities.The diversity of different groups of soil animals significantly and positively correlated with soil pH and phosphorus content.The resulted of the study show that long-term warming could affect the community composition,diversity and nutritional structure of soil faunas in alpine meadows,but epigeic arthropods and soil nematodes are more sensitive than soil arthropods to the long-term warming.The adverse effect of global warming on soil faunas community can be mitigated by adjusting soil pH and phosphorus content in alpine meadows.The above research results can provide a scientific basis for strengthening the utilization and management of alpine meadow ecosystems under the background of global change. |
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