| On the basis of the field investigation, the plant communities in Pangquangou Nature Reserve, Shanxi were studied by the method of quantitative vegetation ecology, including the classification and ordination, plant functional groups of plant communities and carbon density of the forest communities. The research purposes of this study were to understand the species composition of the plant communities and ecological relationships between species and environment, the function characteristics of the plant communities, the relationships between the forest communities carbon density and variety of biological and environmental factors, carbon sequestration capacity of the different forest conmmunities. These results could be regarded as some theoretical basis for biodiversity protection and forest carbon management in this area.The185quadrats in the plant communities of this area were classified into20Associations by TWINSPAN, including:Ⅰ. Ass.Spiraea trichocarpa-Circaea alpina; Ⅱ. Ass. Rosa xanthina-Artemisia brachyloba+Puccinellia distans; Ⅲ. Ass. Quercus wutaishanica-Rosa bella-Thalictrum petaloideum; Ⅳ. Ass. Pinus tabulaeformis+Quercus wutaishanica-Rosaxanthina+Cotoneaster acutifolius-Carex stenophylloides;Ⅴ. Ass. Populus davidiana+Betula platyphylla-Spiraea pubescens-Carex stenophylloides;Ⅵ. Ass. Betula platyphylla-Corylus mandshurica-Carex stenophylloides; Ⅶ. Ass. Larix principis-rupprechtii-Rosa bella+Spiraea pubescens-Carex stenophylloides; Ⅷ. Ass. Picea meyeri+Larix principis-rupprechtii-Ranunculus japonicus+Carex stenophylloides;Ⅸ. Ass. Hippophae rhamnoides+Ribes burejense-Fragaria orientalis;Ⅺ. Ass. Larix principis-rupprechtii-Fragaria orientalis; Ⅺ Ass. Hippophae rhamnoides-Fragaria orientalis;Ⅻ. Ass. Hippophae rhamnoides+Rosa xanthina-Fragaria orientalis+Geranium carolinianum; ⅩⅢ. Ass. Hippophae rhamnoides-Deyeuxia arundinacea; ⅩⅣ. Ass. Artemisia brachyloba;ⅩⅤ. Ass. Rosa xanthina-Poa nemoralis;ⅩⅥ. Ass. Festuca rubra+Potentilla fragarioides;ⅩⅦ. Ass. Kobrecia pygmaea;ⅩⅧ. Ass. Taraxacum mongolicum+Potentilla multicaulis;ⅩⅨ. Ass. Caragana jubata-Carex stenophylloides+Taraxacum nutans;ⅩⅩ. Ass. Daucus car ota+Polygonum viviparum+Anaphalis hancockii. The ordination results of the communities from DCA were as following:the first axis of the DCA ordination from left to right was the forest communities, shrub communities, herbaceous communities and then to the subalpine shrub communities and it reflected the change of the dominant species’life form; the second axis reflected the change of altitude which gradually increased from the bottom to the upper boundary of the ordination diagram. Moreover, the results of the70species’and185quadrats’ordination showed the same trend.Combined with the results of the interspecific association and cluster analysis, the plant functional groups in this area based on the constuctive and dominant species of the forest communities, shrub communities and herb communities were identified. The interspecific relationships were analyzed by using Fisher’s exact test and Spearman’s rank correlation coefficient. The results showed that the species of forest communities and herb communities were negatively associated and communities relationships were not very close, the species of shrub communities were positively associated and communities relations were close. Combined with the results of cluster analysis, the8constuctive and dominant species of the forest communities were classified into4plant functional groups(PFGs), the9constuctive and dominant species of the shrub communities were classified into4PFGs, the16constuctive and dominant species of the herb communities were classified into5PFGs. Species within each plant functional groups showed a significant positive association basically and the correlation between each plant functional groups was relatively small.The carbon density of the forest communities in this area were intended to study from four aspects:(1) The111quadrats of the forest communities were classified into8formations by TWINSPAN, including:Form. Picea meyeri+Larix principis-rupprechtii; Form. Picea wilsonii; Form. Larix principis-rupprechtii; Form. Picea wilsonii+Picea meyer; Form. Betula platyphylla+Populus davidiana; Form.Pinus tabulaeformis+Quercus wutaishanica; Form. Quercus wutaishanica+Populus davidiana; Form.Betula platyphylla. The forest carbon density of different formations were estimated by using the variable BEF (Biomass Expansion Factor) method. The results showed that different forest formations had different carbon sequestration capacity. The biggest average carbon density was Form.Picea wilsonii+Picea meyeri and its average carbon density was94.08t/hm2, the smallest average carbon density was Form.Quercus wutaishanica+Populus davidiana and its average carbon density was38.73t/hm2. The average carbon density of the coniferous forest formations(79.22t/hm2)was bigger than the average carbon density of the broad-leaved forest formations(48.75t/hm2);(2) The forest vegetation carbon density of different altitude, slope position, aspect, slope gradient were estimated by using the variable BEF method. The results showed that the forest carbon density increased firstly and then decreased along with the increasing of elevation, the maximum value was81.45t/hm2which at an altitude of2000-2200m; the forest carbon density was the highest in the flat area which was105.48t/hm2, while it was the lowest in the valley which was49.97t/hm; the forest carbon density was the highest at shady slope which was82.12t/hm2, while it was the lowest at sunny slope which was52.65t/hm2; the steep slope forest carbon density was the highest and it was124.76t/hm2, while the acute slope forest carbon density was the lowest and it was53.38t/hm2;(3) The relationships between forest carbon density and variety of biological factors and environmental factors were analyzed by using DCCA. The results indicated that the environmental factors such as slope gradient, latitude, slope position, elevation played a major role for the quadrats carbon density and dominant species carbon density of the forest communities. The biological factors such as diameter at breast height (DBH), height, density also played a major role;(4) Based on the multiple linear regression model, the various biological factors and environmental factors which affecting forest carbon density were analyzed quantitatively. Multiple linear regression equation of forest carbon density was: Y=14088.534+23.968X1+1.595X2-0.019X3+40.5271nX3+49.6241nX4-245.220X5-46.259X6, the equation showed that the forest carbon density and canopy density(P=0.01), height(P<0.05), DBH(P<0.01) were positively correlated, while the forest carbon density and latitude(P<0.05), longitude(P<0.05) were negatively correlated,, the partial correlation of forest carbon density and elevation, aspect, slope gradient, slope position were not significant(P>0.05), the forest carbon density increased firstly and then decreased along with the increasing of density, when the density of more than1495trees per hectare, the carbon density started to decrease. The partial correlation coefficient of carbon density and density logarithm was the highest(P<0.01)and then DBH logarithm and density(P<0.01), it suggested that density(density logarithm and density) played more important role than the other factors for forest carbon density. |
PDF Full Text Request