Study On The Biodiversity And Niche Of Natural Secondary Forest Communities In The Northern Mountain Of Hebei Province

We analysis the species diversity and niche in tree,shrub and grass layers in secondary forests in north Hebei, here are the major conclusions:(1)We checked out the dominant species in each layers according to its important values. We find that the dominant species in tree layers are Quercus mongolica,Pinus tabuliformis,Larix gmelinii,Betula dahurica,Betula platyphylla and so on; Spiraea salicifolia,Corylus mandshurica,Lespedeza bicolor and Cornus alba are the dominant species in shrub layers; while in grass layers, Elymus dahuricus,Dendranthema chanetii,Iris dichotoma,Polygonatum odoratum,Thalictrum squarrosum and Artemisia tanacetifolia are dominant species. In regenerate layers, the dominant species are Pinus tabuliformis,Acer pictum subsp and Quercus mongolica. Larix gmelinii,Betula dahurica and Betula platyphylla are dominant species in tree layers, but they were not found in regenerate layers, which indicate that these species have less regenerate capacity and may be the losers in community succession, on the contrary, Quercus mongolica and Pinus tabuliformis which dominated both in tree layer and regenerate layer may be winners and the potential dominant species of the whole community.(2)we clarified the vegetation in this area into 7 kinds of communities according to the dominant species in tree layer: predominate by Quercus mongolica,predominate by Populus davidiana,predominate by Betula platyphylla,predominate by Betula dahurica,Larix gmelinii- Betula platyphylla-Betula dahurica,Pinus tabuliformis-Quercus mongolica,Acer pictum subsp-Quercus mongolica-Betula dahurica. What's more, we analysis the species richness,diversity,evenness of the different communities.As for the species richness in tree layers,the species richness:Acer pictum subsp-Quercus mongolica-Betula dahurica>predominate by Populus davidiana>Larix gmelinii- Betula platyphylla-Betula dahurica > predominate by Quercus mongolica > predominate by Betula platyphylla > Pinus tabuliformis-Quercus mongolica>predominate by Betula dahurica;diversity:Acer pictum subsp-Quercus mongolica-Betula dahurica>Larix gmelinii- Betula platyphylla-Betula dahurica>predominate by Betula platyphylla > Pinus tabuliformis-Quercus mongolica > predominate by Quercus mongolica > predominate by Populus davidiana >predominate by Betula dahurica;evenness of the different communities:Acer pictum subsp-Quercus mongolica-Betula dahurica>Pinus tabuliformis-Quercus mongolica>predominate by Betula platyphylla>Larix gmelinii- Betula platyphylla-Betula dahurica>predominate by Quercus mongolica>predominate by Populus davidiana>predominate by Betula dahurica。As for the species richness in shrub layers,the species richness:predominate by Populus davidiana > predominate by Betula platyphylla > Acer pictum subsp-Quercus mongolica-Betula dahurica>predominate by Betula dahurica>Larix gmelinii- Betula platyphylla-Betula dahurica > predominate by Quercus mongolica>Pinus tabuliformis-Quercus mongolica;diversity:predominate by Betula platyphylla > predominate by Populus davidiana > Acer pictum subsp-Quercus mongolica-Betula dahurica>predominate by Betula dahurica>Larix gmelinii- Betula platyphylla-Betula dahurica > predominate by Quercus mongolica>Pinus tabuliformis-Quercus mongolica;evenness of the different communities:predominate by Betula platyphylla>predominate by Betula dahurica>Acer pictum subsp-Quercus mongolica-Betula dahurica>predominate by Populus davidiana > predominate by Quercus mongolica > Larix gmelinii- Betula platyphylla-Betula dahurica>Pinus tabuliformis-Quercus mongolica。As for the species richness in grass layers,the species richness:predominate by Betula platyphylla > Larix gmelinii- Betula platyphylla-Betula dahurica >predominate by Betula dahurica > predominate by Quercus mongolica >predominate by Populus davidiana>Pinus tabuliformis-Quercus mongolica>Acer pictum subsp-Quercus mongolica-Betula dahurica;diversity:predominate by Betula platyphylla > predominate by Betula dahurica > Larix gmelinii- Betula platyphylla-Betula dahurica>predominate by Quercus mongolica>predominate by Populus davidiana > Pinus tabuliformis-Quercus mongolica > Acer pictum subsp-Quercus mongolica-Betula dahurica;evenness of the different communities:predominate by Betula dahurica > predominate by Quercus mongolica >predominate by Populus davidiana>predominate by Betula platyphylla=Larix gmelinii- Betula platyphylla-Betula dahurica > Pinus tabuliformis-Quercus mongolica>Acer pictum subsp-Quercus mongolica-Betula dahurica。As for the species richness in regenerate layers,the species richness:predominate by Populus davidiana>Acer pictum subsp-Quercus mongolica-Betula dahurica>predominate by Betula dahurica>predominate by Betula platyphylla>Pinus tabuliformis-Quercus mongolica>predominate by Quercus mongolica>Larix gmelinii- Betula platyphylla-Betula dahurica;diversity:predominate by Populus davidiana>Acer pictum subsp-Quercus mongolica-Betula dahurica>predominate by Betula dahurica > predominate by Betula platyphylla > Pinus tabuliformis-Quercus mongolica > Larix gmelinii- Betula platyphylla-Betula dahurica > predominate by Quercus mongolica ; evenness of the different communities : Larix gmelinii- Betula platyphylla-Betula dahurica > Pinus tabuliformis-Quercus mongolica>predominate by Betula dahurica>predominate by Betula platyphylla > predominate by Quercus mongolica > Acer pictum subsp-Quercus mongolica-Betula dahurica>predominate by Populus davidiana。(3)We investigated theβdiversity e.g. the similarity of species composition in different communities of the degraded forests. According to our result, the average similarity in tree,shrub,grass and regenerate layer is 0.489, 0.492,0.509 and 0.583 respectively.(4)Species ability to adapt to the environment and to capture the resources can be reflected by its niche breath. We calculated the Levins and Hurlbert niche breath of species living in north Hebei.In the tree layer, Quercus mongolica and Pinus tabuliformis possess the widest niche breath, their LNB is 0.983 and 0.844 respectively, Sorbus pohuashanensis and Malus baccata occurred only in one plot and their LNB is 0, the remaining species posesse a LNB ranged from 0.140 to 0.721. in the shrub layer, Spiraea salicifolia posses the widest niche breath, its LNB is 1.077, while Ulmus davidiana occurred only in one plot, the LNB of remaining species ranged from 0.220 to 0.882. In grass layers, Elymus dahuricus and Polygonatum odoratum posses the widest niche breath, and their LNB are 1.169 and 1.165 respectively, Plantago asiatica,Roegneria kamoji,Potentilla chinensis occurred only in one plot and their LNB is 0, the LNB of remaining species ranged from 0.002 to 1.139.(5)As for the overlap of niche, grass layer have the biggest niche overlap, its value is 0.662, the niche overlap in shrub and tree layers are 0.192 and 0.147 respectively. Two different cases may result in high niche overlap: both the two species have large niche breath; species have small niche breath but occurred in the same resource dimension. While as for the species which have narrower niche breath or they belong to different resource dimension, the niche overlap will be small. In the tree layer, Quercus mongolica,Pinus tabuliformis and Tilia tuan have wild niche breath, and the niche overlap among these species are very huge. While the niche breath of Sorbus pohuashanensis and Populus davidiana are very narrow, but they also have niche overlap; In the shrub layer, niche overlap among some wild-niche breath species such as Spiraea salicifolia,Lespedeza bicolor,Weigela florida are very huge, in the contrary, some narrow-niche breath species such as Ulmus macrocarpa and Ulmus davidiana also have a huge niche overlap.(6)As for the niche similarity, grass layer have the biggest similarity, its value is 0.562. While the niche similarity in shrub and grass layers are much smaller, its values is 0.144 and 0.143 respectively, and there are no significant variation in these two layers. In tree layer, Sorbus pohuashanensis×Populus davidiana,Ulmus davidiana×Acer pictum subsp,Betula platyphylla×Larix gmelinii,Tilia tuan×Acer pictum subsp showed a relatively higher similarity, while in the shrub layer, Spiraea salicifolia×Lespedeza bicolor,Eleutherococcus senticosus×Lonicera chrysantha,Ulmus macrocarpa×Ulmus davidiana,Weigela florida×Corylus mandshurica,Lonicera chrysantha×Corylus mandshurica showed a relatively higher similarity, Polygonatum odoratum×Elymus dahuricus,Polygonatum odoratum×Saussurea japonica,Artemisia lavandulifolia×Elymus dahuricus,Artemisia lavandulifolia×Saussurea japonica showed a relatively higher similarity in grass layer. These species have the same priority in resource, the wild niche breath and its biology character may result in their co-occurring.