Characteristics Of Soil Fauna Community In Different Forest Age Chinese Fir Plantations In Rainy Zone Of West China

Chinese fir is widely cultivated in China and has important economic and ecological benefits.The rapid growth of Chinese fir consumes a lot of soil nutrients,which may cause changes in soil quality and micro-environment.Soil fauna participate in the material cycle and energy flow of forest ecosystems,which is important components of biodiversity and have an ecological indicator of soil quality.The changes of soil quality caused by Chinese fir at different growth stages may cause the response of soil fauna.The research on the influence of Chinese fir plantation in different developmental stages on soil fauna is rare.In this paper,three forest age Chinese fir plantations(10a,17 a,25a)were used as research objects.The community composition,diversity characteristics and functional groups of soil fauna in three forest ages were investigated in different seasons.Correlation analysis between vegetation,soil physical and chemical properties,soil enzyme activity,soil microbial biomass and soil fauna.Conclusion as below:(1)A total of 15 424 soil animals were collected,belonging to 5 phyla,14 classes,31 orders,and 165 families.The dominant species were Nematode and Podocinidae.The frequent species were Isotomidae,Oonopidae,Xenocaligonellidae,etc.9 families.The remaining 154 groups constituted the rare group.The average density and groups of soil fauna in three forest ages were ranked as: 17 a > 10 a > 25 a.The distribution of soil fauna in three forest ages showed surface aggregation characteristics;In the 10-year-old Chinese fir forest,the average density of soil fauna in the third soil layer was higher than that in the second soil layer,and there was a reverse distribution phenomenon.(2)The Shannon-Wiener diversity index of soil fauna in the 10-year-old Chinese fir forest was lower than the 25-year-old Chinese fir forest in January.The Margalef richness index of soil fauna in the 10-year-old Chinese fir forest was extremely significant(P < 0.01)lower than that in the 17-year-old Chinese fir forest and the 25-year-old Chinese fir forest in Apri.The Margalef richness index of soil fauna in the 25-year-old Chinese fir forest was significant(P < 0.05)lower than that in the 10-year-old Chinese fir forest and the17-year-old Chinese fir forest in October.In the seasons,the 17-year-old Chinese fir forest plantation have the highest soil fauna diversity index.The omnivorous soil fauna accounted for the majority of the soil fauna functional groups in the three forest age Chinese fir plantations.The redators soil fauna accounted for the highest proportion in the17-year-old Chinese fir forest;The saprozo soil fauna accounted for the highest proportion in the 10-year-old Chinese fir forest;The phytophage soil fauna accounted for the highest proportion in the 25-year-old Chinese fir forest.(3)The soil total phosphorus content was extremely significantlynegatively correlated with the density of the macro-soil fauna,and the soil water content was significantly negatively correlated with the group number of the macro-soil fauna.The soil microbial biomass carbon was significantly positively correlated with the group number of the meso-micro soil fauna in October.The polyphenol oxidase activity was significantly negatively correlated with the average density of soil fauna and the average density of the meso-micro soil fauna in April.The acid phosphatase activity was significantly positively correlated with the average density of soil fauna,the average density of the meso-micro soil fauna,the group number of soil fauna,the Shannon-Wiener diversity index of soil fauna,the Margalef richness index of soil fauna in July.The acid phosphatase was significantly positively correlated with the group number of soil fauna,the group number of the meso-micro soil fauna,the soil fauna Pielou evenness index,and the soil fauna Shannon-Wiener diversity index in October.The difference of forest age affected the soil fauna characteristics of Chinese fir plantation.In contrast,the 17 a plantation had higher vegetation diversity and good forest environment,which was conducive to the stability and diversity of soil fauna community.It is suggested that soil animal diversity should be used as a judgment indicator for the good diversity of plantation ecosystems in future plantation management.