Study On The Hillsides Closing Years Effected On Theunderstory Plants Diversity In Broadleav Forests Southern Anhui Area

Closing hillsides to facilitate afforestation plays an irreplaceable role in the composition of undergrowth vegetation,natural regeneration and succession of forest.In this paper,the research studied the recovery processes by selecting stands of different ages since hillside closing in moutains areas in Qiaomu village,Qingyang county,Southern Anhui province.I addressed the following research:the structure and diversity of understory vegetation in Southern Anhui province;the change law of micro-environment in forest,and the correlation between diversity of understory vegetation and microc-environment.The study examined the dynamic processes of diversity and biomass since hillside closing,aiming to provide theoretical basis for the protection of species diversity and ecosystem function stability of natural secondary forests in the Southern Anhui mountains,and it also provides data support for further relevant studies on biomass,productivity and ecological function,and it provides a theoretical guidance for wildly using of setting apart hills for forest recovery in Wannan mountains area.We came to the following conclusion.(1)Closing hillsides to facilitate afforestation could improve diversity of understory vegetation.There were a total of 88 species belonging to 42 genera and 61 families in shrub layer,a total of 135 species belonging to 68 generas and 106 families in herb layer.The diversity of undergrowth vegetation showed significant difference since hillside closing.The diversity index of shrub layer was M-shaped,and the two peaks occurred when the years of closing hillsides were 10 and 30 years.The species richness of undergrowth shrub layer gradually increased with the increase of closing time,and the species richness of old growth shrub layer decreased.The species richness of undergrowth shrub layer increased with the increase of the closing time,but the species richness of old age shrub layer decreased.The species diversity of the herb layer also showed a significant difference in different years,and its richness index and diversity index also showed a trend of increasing first and then decreasing.The evenness index and diversity index have the same change rule.(2)There were significant differences in temperature and humidity between different years.The surface temperature in the forest and the temperature at 1.3 meters showed a consistent trend of unimodal change,which increased first and then decreased,and reached the peak around 3 p.m.The highest temperature in a singleday is the highest in the forest when the years of closing hillsides was 10.The composite score of principal component analysis about main climatic factors in different closing year were sorted: 5year>10year>0 year>20 year>old>30 year.(3)The plant diversity index under shrub layer and herb layer forest was correlated with evenness,richness and air temperature and humidity.The herb layer diversity index has a significant positive correlation with the surface temperature and the temperature at 1.3 meters.The diversity index and richness of shrub layer were positively correlated with temperature and humidity,while the evenness index was negatively correlated with local climatic factors.