Studies On Population Ecology Of Subalpine Birch Forests In The Northeast Border Of The Qinghai-Xizang Plateau

The subalpine of the northeast border of the Qinghai-Xizang Plateau locates in the ecotone among the monsoon region of east China,arid region of west China and alpine and cold region of the Qinghai-Xizang Plateau. Birch forest,as one of the transitional forests in the succession series of subalpine,middle mountain and hill,is an important component of the forests in this region. The study of population ecology of birch forests in this region can make us know more about birch population growth and community characteristics,offering theoretical basis of ecosystem management of secondary forest and its restoration and rehabilitation in the ecotone among the monsoon region of east China,arid region of west China and alpine and cold region of Qinghai-Xizang plateau and accumulating the basal information for the vegetation succession.Based on the plant community ecology and population ecology,species composition and quantitative characteristics,species diversity,community similarity and cluster analysis,population structure,population spatial distribution pattern and interspecific association of different sample stand of 10 birch forests in the northwest border of Qinghai-Xizang plateau were analyzed. The results showed as follows:1. The tree and shrub of subalpine of the northwest border of Qinghai-Xizang plateau was consist of 67 species,belonging to 21 families and 37 genera. Rosaceae(17 species), Caprifoliaceae(12 species), Salicaceae(9 species), Pinaceae(6 species) had more species. Salix(10 species) and Lonicera(8 species) had more species.2. The total diversity indexes of DS,H',HB and DMC showed the same rule that the diversity indexes of Betula platyphylla—Populus davidiana—Quercus wutaishanica mixed forest,Betula platyphylla—Fargesa nitida forest and Betula platyphylla—Populus davidiana forest were higher;the diversity indexes in tree layer of the sample plot(sQi) also showed the same rule that Q4>Q8>Q6>Q2>Q5>Q1>Q10>Q7>Q9>Q3;the diversity indexes in shrub layer showed the same rule that Q4>Q8>Q6>Q2>Q5>Q1>Q10>Q7>Q9>Q2.3. On the basis similar coefficient and dissimilar coefficient,the birch forests in the...