Abundance And Diversity Of Soil Nematode Community In Natural Forests At Different Altitudes In Cold-temperate Climate Zone

Soil nematode is an important part of the food web,which is very important to soil nutrient cycle.The space-time distribution of community biogeographic pattern and its main driving factors have received a widespread attention.However,the previous research has mainly focused on the low and middle latitudes,and less on the high latitudes cold temperate zone.The structural characteristics and the variation rules of soil nematode community along the different seasonal dynamics and soil depth along the altitude gradient are still not clear,which hinders us to understand and compare soil nematode diversity at different space and time scale.To explore soil nematode community altitude distribution pattern and its driving mechanism in cold temperate zone,we set a total of six altitude gradient(750,830,950,1100,1300 and 1420 m),in the northern part of the Great Khingan Mountains,and collected soil samples in in May,July and September,respectively.in A total of 90 soil samples of different seasons,altitude and soil depth were collected.Illumina MiSeq sequencing method was used to investigate the community composition and structure characteristics of soil nematodes in the 0-10 cm and 10-20 cm layers along the altitude gradient under different seasonal dynamics.The results showed that:(1)The diversity of soil nematode community in cold temperate zone along the altitude gradient showed a monotone decreasing pattern.Three classes,12 orders,37 families and 58 genera were measured,including 17 genera of Bacterivores,8 genera of Fungivores,20 genera of Plant-parasites,10 genera of Omnivores-predators and 3 genera was unclassified.Bacterivores was the dominant vegetative group in this area.(2)Altitude gradient had a significant effect on soil nematode community structure.The ?diversity index of soil nematodes,such as Sobs,Shannon,Chaol and Faith's PD,was significantly different at different altitudes,and tended to decrease with the increase of altitudes.Soil pH and soluble organic nitrogen were the key factors explaining the change of nematode community composition.(3)There was no significant difference in a diversity but significant difference in ?diversity among different seasons.In May,July and September,soil nematode abundance and diversity were negatively correlated with altitude.The effect of altitude gradient on soil nematode community structure was stronger than that of seasonal variation.Soil available nutrients,such as ammonium nitrogen,soluble organic carbon and nitrogen,all played significant roles.Soil moisture content and soil temperature were also important environmental factors to explain the seasonal dynamics of soil nematode community structure.(4)The ? and ? diversity of soil nematodes were significantly different with the change of soil depth.The abundance and diversity of soil nematodes in the 0-10 cm and 10-20 cm soil layers showed a monotonically decreasing pattern along the altitude gradient.In the cold temperate forest ecosystem,the composition of some nematode communities varied at different soil depths,but altitude had a more significant effect on the structure and diversity of soil nematode communities.Redundancy analysis showed that there was no difference in the effects of various environmental factors on soil nematode community in different soil layers,but soil bulk density and soil ammonium nitrogen all had significant effects on soil nematode community.