Influence Of Phyllostachys Edulis Expansion On Soil Fauna Community And Food Web In Lushan Mountain

The moso bamboo and Japanese cedar are both the typical vegetations in the Lushan Nature Reserve.In recent years,with their unique growth characteristics,moso bamboo had gradually expanded into the surrounding forest such as evergreen forest,coniferous forest or coniferous and broad-leaved mixed forest communities,then dominated and replaced them.The majority of plantation Japanese cedar pure forest had been invaded by the moso bamboos and transfer to a moso bamboo-Japanese cedar interlace forest.However,the ecological impacts of the expansion of the bamboo in the ecological community most had focused on soil fertility,environmental heterogeneity,plant diversity,and bird diversity,et al.,and little research has been done on the effects of underground organisms.The soil animal community of the underground organisms is an indispensable part of the soil ecosystem.It contributes greatly to soil formation,nutrient cycling,and energy conversion,and it make a great effect of improving forest soil fertility.But due to soil animals were sensitive to environmental changes,the composition and distribution of soil animals would change once the environment changes,directly or indirectly affecting the characteristics of forest soils.Therefore,it was of ecological significance and reference value to study the effect of bamboo expansion on soil animal community.Under the condition,the study used the Tullgren funnel method and pitfall trap method to capture soil animals,observed the effects of bamboo expansion and felling the expansive bamboo on soil animal communities and their food webs.The first experiment set three sites,moso bamboo pure forest,Japanese cedar pure forest,and Moso bamboo-Japanese cedar interlaced zone,respectively.The second experiment set two sites,undeforested area with the bamboo contained,and deforested area with bamboo cut down.Following were our results:During the process about moso bamboo expanded to Japanese cedar pure forest,soil pH and other nutrient contents in the forests had changed.The pH value in the forests gradually increased,the total potassium content,available potassium,and total phosphorus content increased.The content of organic matter and total nitrogen decreased.The content of available phosphorus did not change much,but it still decreased.The expansion of moso bamboo to pure Japanese cedar forest resulted in changes in vegetation environment and soil nutrients,the seasonal dynamics of soil animal density and biomass were also different.The soil animal diversity index did not differ significantly among the three forests,but the diversity indices of moso bamboo pure forest was lower,and the soil animal structure in the interlaced zone was more similar to the Japanese cedar pure forest.The peak soil density of moso bamboo pure forest and Japanese cedar pure forest showed a difference about a two months interval.The underground soil fauna density of moso bamboo pure forest got a highest value only in May,and lower than the Japanese cedar pure forest in other months.It was because of the lower content of soil nutrient and thin litter in moso bamboo pure forest;the above-ground soil fauna were more in spring,summer and autumn,mainly due to the increase in the number of soil animals with strong ability to fly and move.The responses of different soil animal groups to bamboo expansionwere different,which was related to the habits,feeding behavior of soil animal and the litter decomposition.Moreover,the expansion of moso bamboo did not change the trophic level of Collembola and Oribatida,but decline the trophic levels of the Mesosotigmata and Coleoptera,the trophic level of the Hymenoptera increased first and then decreased.Araneae and Pseudoscorpionidea still kept a high trophic level.The changes of trophic level was related to environmental changes,the food resources and the life history of soil animals.After deforested the moso bamboo,when compared to the undeforested area,the pH of the deforested area increased first and then decreased,the content of organic matter,total nitrogen and total phosphorus increased,the total potassium content decreased,and the available potassium showed a jagged change.The results of the study showed that the density of soil animals generally decreased after the deforestation,indicating that the environmental changes of deforestation had a greater impact on soil animals;the numbers of Acari,Collembola,Coleoptera fell after deforestation.The number of Hymenoptera,Araneae,Orthoptera increased.The results of the diversity index also showed that the diversity of soil animals in the undeforested area was slightly higher than that in the deforested areas.Changes in the composition of soil animals caused by deforesting moso bamboo also affected the trophic level of soil animals.After the implementation of the deforestation,the trophic level of soil animals was generally down.The trophic level of Prostigmata became higher,Pseudoscorpionidea and Symphyla reduced theire trophic level,Diptera,Collembola,and Hymenoptera all fell to the second grade,but Mesostigmata,Chilopoda,Diptera larvae and Coleoptera larvae kept in third grade.The alteration in trophic levels was related to the impact of deforestation on moisture,light,heat,and vegetation in the forest.