Responses Of Sandstone Peak Forest Plant Communities To Habitat Factors

The vegetation community is an important component of the ecosystem,and the decrease of plant diversity is the most significant manifestation of vegetation degradation,while habitat conditions are the key factors affecting plant species diversity.Therefore,it is important to understand the habitat characteristics of plant communities and to investigate the evolution of the species composition of vegetation communities and their diversity under different habitat-s,to reveal the operation mechanism of plant species diversity maintenance and the conservation and stability of plant diversity.In this paper,the relationship between plant community diversity and soil factors(carbon,nitrogen,phosphorus,potassium,calcium,magnesium,pH)and topographic factors(elevation,slope orientation,slope position)in sandstone peak forest landscapes was investigated in Zhangjiajie National Forest Park.The results showed that:(1)A total of 315 plant species were surveyed.The plants in the tree layer are mainly legumes and Magnoliidae,the plants in the shrub layer are mainly Rosaceae and Leguminosae,and the plants in the herb layer are mainly Asteraceae and Labiatae.The geographical composition of plant families is Pantropic,and the geographical composition of genera is dominated by three distribution types:Pantropic distribution,North temperate distribution and East Asian distribution,and there are relict plants such as Eucommia,dove,and gooseberry.(2)Response of plant diversity to topographic factors.For the 400-1 220 m elevation range in Zhangjiajie National Forest Park,the study showed that:①the differences in TCa,TMg and TP were significant(P<0.05)between groups at different Elevation gradients,while the differences in soil factors were not significant(P>0.05)at different slope directions and slope positions.②The overall plant diversity index gradually increased with elevation,and the plant diversity index of tree layer showed a "U" shape change with elevation,while the differences of plant diversity of shrub layer and herb layer were not significant at different elevation gradients.③The differences of plant diversity in different slope directions and slope positions were not significant.(3)Regression analysis of plant diversity and soil factors.①Simpson’s index was negatively correlated with TC content at 400-600 m elevation gradient(P<0.05).Simpson and Pielou indices were negatively and significantly correlated with TC,TN,and TP,and the Shannon-Wiener index was negatively and significantly correlated with TN and TP at the 800-1 000 m elevation gradient;the species richness index was negatively and significantly correlated with TK,TMg.The species richness index was significantly and positively correlated with TK and TMg content on the 1 000-1 220 m elevation gradient.②On the east slope gradient,the species richness index,Simpson index,and Shannon-Wiener index were significantly and negatively correlated with pH,and the Simpson index was significantly and negatively correlated with TCa;on the south slope gradient,the plant diversity index was significantly and negatively correlated with TN,and the Simpson index,Shannon-Wiener index,and Pielou index and TC were significantly negatively correlated;on the north slope gradient,Simpson index,Shannon-Wiener index,Pielou index and TP were significantly negatively correlated.③On the downslope position.species richness was significantly and negatively correlated with pH,Simpson index was significantly and positively correlated with TMg,and Pielou index was significantly and negatively correlated with TP;on the mid-slope position,species richness,Simpson index,and Shannon-Wiener index were significantly and positively correlated with TK;on the upslope position,Simpson index,Shannon-Wiener index and Pielou index were significantly and negatively correlated with TK and TP.(4)Analysis of variance decomposition of various habitat factors.Topographic factors explained the highest plant diversity,followed by pH,and the lowest soil nutrients.The overall plant diversity index was significantly(P<0.05)influenced by elevation and pH,while the plant diversity of tree layer was not significantly influenced by habitat factors,the plant diversity index of shrub layer was significantly influenced by slope direction and Mg content,and the plant diversity of herb layer was also significantly influenced by elevation.In summary,for the area of Zhangjiajie National Forest Park,elevation has the most significant effect on the overall plant diversity and the plant diversity of the herbaceous layer,and the overall plant diversity is also influenced by pH,while the plant diversity index of the shrub layer is significantly influenced by slope orientation and total magnesium content.Therefore,in the conservation and restoration of plant diversity in the subtropical peak forest landscape represented by Zhangjiajie National Forest Park,priority should be given to elevation and soil pH in general,and priority should be given to slope orientation and TMg content in the construction of shrub layer,based on the pattern of plant community diversity along the habitat factors,and suitable trees for the land,so as to realize the scenery that is better than natural although artificial.