The Functional Traits And Natural Recovery Dynamics Of Woody Plant Seedlings In The Subtropical Mixed Evergreen And Deciduous Broadleaved Forests In Southwest Of Hubei Province

The subtropical evergreen-deciduous mixed broad-leaved forest is one of the most representative vegetation types in the region of Wuling Mountain, this vegetation type plays an unique role in terms of preserving the regional ecological environment. The community succession and recovery depends on the species diversity and plant functional traits of the seedlings. The seedlings from the three recovery phase after disturbed including the 20 years forest, the 35 years forest and the old-growth forest have been studied in this aticle. Based on the investigating of community ecology and the determining of plant functional traits, this article utilizes multiple research method of mathematical statistics including multiple comparison, analysis of variance and correlation analysis to reaserch the dynamic of natural recovery about the species diversity and plant functional traits of the seedlings and compare the plant functional traits between the seedlings layer and the mature trees in community, which can provide some theoretical foundations for recovering naturally and maintaining the biodiversity of the subtropical evergreen and deciduous broad-leaved mixed forest. The main results are as follows:1. The subtropical evergreen and deciduous broad-leaved mixed forest in Mulinzi natural reserve includes 33 kinds of seedings from 14 familys and 25 genus, this seedings are made up of 19 kinds of evergreen tree species and 14 deciduous tree species. The accumulated rate of the species-area curve and the species-abundance of the old-growth forest is higher than the secondary forests, which indicates that the plant species composition and the biodiversity of the secondary forest is close to the old-growth forest. The change of different functional group presents an obvious regularity that the richness and abundance of the deciduous tree species reduces gradually with the delay of recovery time, but the evergreen tree species increases gradually. The number of specise of the early succession reduces gradually, but the late succession increases gradually. The species composition of different recovery stages has a significant correlation(P < 0.05)with the total nitrogen(TN)and the totalphosphorus(TP) of the soil. The height of plant individuals in different natural recovery shows a "unimodal type" that the 35-year secondary forest communities is higher than the natural secondary forest communities and the 20 years old.2. The research about the plant functional traits of seedlings in different recovery stages in Mulinzi nature reserve indicates that the SLA, SSL and SRL of the two secondary forest(the 20 y and the 35y) is higher than the old-growth forest, but there no differences between the two secondary forests. With the delay of recovery time, LMF increasing significantly, while RMF reduceing significantly, and SMF dose not show differences significantly. Seedlings function diversity index, richness(FRic),functional evenness(FEve), function(FDis) and discrete degrees(Rao ’s) quadratic entropy change significantly. Although the functional richness(FRic), functional evenness(FEve), function(FDis) and discrete degrees(Rao ’s) secondary entropy in 20 years secondary forest, and no significant difference between 35-year secondary forest,but there was a significant difference with the old-growth forest, its change trend is rising first and fall after. The leaf area(SLA), the stem(SSL), the proportions of the substances(LMF) and dry matter of stem(SMF) of the deciduous species is greater than evergreen tree species in three different restoration stages.3. At the community level, the functional traits of the seedlings are significantly different from those of the adult trees. Specific leaf area and specific stem density of the seedlings and the adult trees are positively correlated. With the passage of time,the changes of the functional properties of the seedlings and the adult trees show a consistent trend. The specific leaf area of both the seedlings and the adult trees decreases, while the leaf dry mass content and specific stem density increases during the recovery process. These above results suggest that the patterns of change in functional traits and their relations for adult trees can be indicated in certain degree by those of the the seedlings.