| As an important part of forest ecosystem,the decomposition process of fallen logs promotes the nutrient cycle of forest ecosystem and maintains forest productivity.The formation of fallen logs also helps to increase the diversity of wood-decaying fungi and protect the precious resources of medicinal wood-decaying fungi.In order to know the existing reserves of fallen logs and the species composition of wood-decaying fungi in Guanshan Nature Reserve.Our study was based on Guanshan Evergreen Broad-Leaved Forest Monitoring Plot which lagre in 12 hectares.Firstly,the quantitative characteristics,decay class and diameter class of fallen logs and snags in the large sample plot were investigated.Then,we also investigated the species diversity of wood-decaying fungi growing on fallen logs.The main results are as follows:(1)In the Guanshan Monitoring Plot with an area of 12 hectares,the stock of fallen logs and snags was 12.69 t/hm~2,of which the stock of fallen logs is 10.54 t/hm~2,which was significantly higher than that of snags(2.15 t/hm~2).The number of fallen logs and snags with diameter of 10-20 cm was large,accounting for 70.8%of the total.The decay class of fallen logs was mainly class III and IV,accounting for 30.55%and 36.64%respectively;Snags are mostly in class II and III decomposition state,accounting for 34.75%and29.43%respectively.(2)The contents of carbon,nitrogen and phosphorus of fallen logs increased with the increase of decay class and diameter class.Changes in stock of three nutrient elements:C(4297.09 kg/hm~2)>N(28.46 kg/hm~2)>P(4.02 kg/hm~2);The carbon and nitrogen contents of snags increased with the increase of decay class and diameter class.There was no significant change in phosphorus of snags among all decay class and diameter class,the stock of three nutrient elements:C(1266.24 kg/hm~2)>N(4.93 kg/hm~2)>P(1.31 kg/hm~2).(3)With the increase of decay class of fallen logs,The species of wood-decaying fungi growing on fallen logs first increased and then decreased.In the decay class IV,the species are the most,with a total of 16 species,and in the decay class V,the species are the least,with only 4 species.The number of wood-decaying fungi growing on fallen logs of different diameter classes:10-20 cm>20-30 cm>>40 cm>30-40 cm.The same species appeared on several fallen logs with different decay classes or different diameter classes.And then,Microporus vernicipes and Xylobolus princeps are the dominant species.The above results show that fallen logs is the main input component of coarse woody debris in evergreen broad-leaved forest in Guanshan Mountain.From the decay class of fallen logs and snags,the decay class of fallen logs belongs to the middle to late stage,while snags are mainly in the early stage of decomposition,which is slower than that of fallen logs.From the change of nutrient content,the nutrient content of fallen logs and snags increased during the decomposition process,which can promote the activities of microorganisms and increase soil nutrients.Wood-decaying fungi are the main microbial groups that decompose wood fiber materials.The change of wood fiber content of fallen logs has a corresponding relationship with the distribution law of wood-decaying fungi.This paper provides reference for the study of nutrient cycle,ecological function and the decomposition relationship between fallen logs and wood-decaying fungi in subtropical evergreen broad-leaved forest. |
