Effects of thinning on soil nutrients and rhizosphere microbial communities of a Cryptomeria fortunei plantation in western Sichuan,China
In this study,we explored the effects of different thinning intensities on soil nutrients,enzyme activities,and community structure and functions of rhizosphere microorganisms to provide scientific guidance for the sustainable management of improved quality and efficiency of Cryptomeria fortunei plantations.Three thining treatments,CK(0％),T36(36.9％),and T49(49.0％),were used to investigate the effects of different thinning intensities on soil nutrients,enzyme activities,and rhizospheric microbial diversity of a 9-year-old C.fortunei plantation in the middle mountain area of western Sichuan.Five main results were obtained.First,thinning increased the content of soil organic carbon,total nitrogen,and hydrolyzed nitrogen in soil collected from the 0-20 cm surface soil layer.The loss of available phosphorus was the greatest for the T49(49.0％)treatment.Second,soil sucrase activity significantly increased after thinning(P＜0.05).The T36(36.9％)treatment significantly increased cellulase activity by 36.9％in the 0-20 cm surface soil layer(P＜0.05).Third,thinning changed the relative abundance of the dominant bacteria in the rhizosphere soil.The relative abundance of Ascomycota in the rhizosphere soil was significantly higher than that in the CK(0％)treatment(P＜0.05).Bacterial richness was not significantly affected.However,the Ace and Chao indices of fungal richness significantly decreased(P＜0.05).Fourth,the relative abundance of bacteria in membrane transport under the T36(36.9％)and T49(49.0％)treatments was significantly higher than that under the CK(0％)treatment(P＜0.05).In contrast,the relative abundance of bacteria in energy metabolism under the CK(0％)treatment was significantly lower than that under the T36(36.9％)treatment(P＜0.05).Fifth,lichenized-undefined saprotrophs were the highest in the T36(36.9％)treatment(P＜0.05).Plant saprotroph-wood saprotrophs,plant pathogens,and animal pathogens in this treatment were significantly lower than those in the CK(0％)treatment(P＜0.05).The collective findings indicate that proper thinning can improve forest quality,promote soil nutrient cycling,increase the relative abundance of beneficial microorganisms,and reduce disease risk.It is recommended to select 1 725±116 trees per ha for C.fortunei plantations in the middle mountains in area of western Sichuan,which can improve the forest quality and maintain the healthy stand environment.
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