Effects Of Natural Enclosure On Phyllostachys Pubescens Stand Structure,Plant Diversity,Soil Physical And Chemical Properties,and Bacterial And Fungal Communities

Currently,the economic profit of Moso bamboo(Phyllostachys pubescens)decreased,which influenced the anthropogenic effort to manage Moso bamboo plantation such as fertilizer application.Therefore,a large area of the bamboo plantation was out of management for the past few years,and was in a state of natural exclosure.To explore the effects of natural exclosure on Moso bamboo forest,in this study,two types of moso bamboo forest(human-manage forest and natural exclosure forest)were chosen in Yuhang District,Hangzhou City.Using the method of space-for-time,4 different plots(0 years,10 years,20 years,and 30 years)were set up,according to the age of natural exclosure.The stand structure of bamboo,understory vegetations,soil physical and chemical properties,soil bacterial and fungal communities under different exclosure duration were studied,and the effects of soil properties on microbial communities were analyzed.The main results are follows:(1)The culm density of bamboos increased gradually with increase of exclosure age,while the average DBH of bamboo decreased significantly(P<0.05).(2)Affected by natural exclosure,the diversity of shrub increased firstly and then decreased which reached its maximum at 20 years,and the diversity of herb decreased with increasing years of exclosure.(3)Because of the lack of trample,soil bulk density(SBD)significantly decreased(P<0.05)with increasing years of exclosure.The vegetation restoration promotes humus accumulation,the concentration of soil organic C(SOC)significantly increased(P<0.05).Affected by the increase of soil organic matter,soil p H decreased significantly in the second decade(P<0.05).In addition,the concentration of available phosphorus(AP),available potassium(AK)and available nitrogen(AN)increased in varying degrees.(4)Affected by natural exclosure,the diversity and richness of soil bacterial community increased firstly and then decreased which reached the maximum at 10 years.The diversity and richness of fungus community increased under condition of excolsure.And the results of ? diversity analysis showed that soil bacterial and fungal communities tended to be stable after 20 years of excolsure.(5)Soil bacterial and fungus communities had a strong correlation with soil nutrients including AK,AP and AN.It indicated that soil nutrients promote the growth of bacteria and fungi.There is a time lag between the increase in soil nutrients and the recovery of soil bacterial and fungal communities,indicating that the response of the microbial community to natural enclosure has a hysteresis.