Study On Early Community And Habitat Dynamics Of Differently Damaged Evergreen Broad-leaved Forests In Tiantong National Forests Park

Ever green broad-leaf forest(EBLF)is a main zonal vegetation in eastern China. The destruction of the EBLF get worse and worse due to the rapid population growing and the fast economic growth.We could see no more original EBLF but secondary ones in this area now,many forests degrade to shrub and even to bald land.It's very important to learn the degradation mechanism and make sense of how to rebuild EBLF.We set 5 ever plots of whichever the size is 20m×20m in Tiantong National Forest Park,Zhejiang province in 2002,this park is one of well-preserved regions of typical evergreen broad-leaved forest.On the consideration of local disturbance,we carry out different treatments in 4 plots to different degradation degrees,leaving one as the comparison in 2003.4 different treatments as follows:plotⅠ,the canopy trees are all selectively cut and the shrubs and herbs are reserved;plotⅡ,all the plants are also clear cut,but the surface soil and the forest floor are reserved;plotⅢ,all of the plants and the surface soil(0～10cm)are removed;plotⅣthe shrubs and herbs are all selectively cut but the canopy trees are reserved;plotⅤ,no treatment as a comparison.In each plot,the habitat factors are inspected,including air temperature and humidity in the height of 0.3m,1.5m and 8.0m,soil temperature and humidity in the depth of 5cm and 20cm,light intension in different height.In the natural restoration part of each plot,the floristic composition and community structure were investigated every season.After 3 years' research,the results indicate:1)Four plots can be divided to 3 different patterns after 3 years' restoration according to the vegetation status:①plotⅠdominated by pre-dominant species, evergreen species like Castanopsis carlesii,Castanopsis fargesii which are dominant in untreated plot become dominant species again.②plotⅡandⅢdominated by new pioneer species such as Litsea cubeba,Choerospondias axiliaris,Clerodendrum cyrtophyllum,and ever green trees grow slowly in these area③PlotⅢdominated by herbage such as Lophantherum gracile,Woodwardia japonica,Hicriopteris glauca,trees regeneration being restrained.2)The daily range of air temperature in each plot at each level during the first 3 years present a descending trend,and in the same year,the rank of daily fluctuate presentedⅡ,Ⅲ＞Ⅰ＞Ⅳ＞Ⅴ.The diurnal variation of the air temperature shows a single peak type curve in each plot,and the peak got samller with rest-orating.The daily rangeof soil temperature(DRST)at two depths in each plot during the 3 years presented a descending trend.In the first year,DRST of each plot at both 5cm depth and 20cm depth ranks as:Ⅲ＞Ⅱ＞Ⅰ＞Ⅳ＞Ⅴ,and in the second year:Ⅱ＞Ⅰ＞Ⅲ＞Ⅳ＞Ⅴ.The diurnal variation of light intensity,in the first year,show a single peak type curve at 0.3m and 1.5m level in 4 damaged plots,and the light intensity ranks as:Ⅲ＞Ⅱ＞Ⅰ＞Ⅳ＞Ⅴ.In the second year,there is only plotⅢkeeping a clear single peak type at 0.3m level,and onlyⅡandⅢat 1.5m level.In the third year, 4 plots exceptⅢshow a gently trend.There's no clear change during 3 years of the plotⅣat 8m level3)Light and soil are two main habitat factors which effect restoration. sufficient light and good soil situation would greatly accelerate the regeneration.4)Four differently damaged plot show different restoration traits,and these could be divided to 4 types:accelerated regeneration,plotⅠ,the ever green species and shrub species grow rapidly after treatment,the community restored quickly;restrained regeneration,plotⅣ,the remain trees and ground layer plants restrain the regeneration of trees;accelerated succession,plot,good soil and light situation do accelerate the succession;delayed succession,comopared toⅡ, plants grow slowly in plotⅢdure to poor seed source and nutrient.5)Many evergreen trees can regenerate througth resprouting.This research proves that resprouting persistence niche do a accelerate affection on 4 damaged plots,and this makes a situation of climax species and accompanying species coexist in plotⅠ,climax species and pioneer species coexist in plotⅡ,Ⅲ, which accelerate the restoration forward climax community.