Habitat Characteristics And Plant Species Diversity Of Dolomite Karst

Shibing karst in guizhou province has developed a typical and complete baiyunyan karst landform,which not only has unique karst natural landscape and aesthetic value,but also has a large area of native forest vegetation and diversified ecosystem,which makes this area have great ecological scientific research value.The success of the application for heritage sites has promoted the development of regional tourism,but it has also affected the species of vegetation and ecological environment.Vegetation is the most important component of the ecosystem and sensitive to human disturbance.The decrease of plant species diversity in the community is often the most obvious manifestation of the community vegetation degradation,while the change of ecological environment is the most important factor affecting the change of community species diversity.Therefore,study the grasp the eco-environmental characteristics of karst area,to explore the changes in the physical composition and diversity in different habitats,the habitat factors and species diversity,helps to reveal the maintaining mechanism of vegetation species diversity of heritage sites of ecological environment protection and the stability of the species diversity and the sustainable development of tourism management and economy is of great significance.Taking the plant community of guizhou shibing karst world natural heritage site as the research object,using the typical sample survey method,to the heritage site acquisition of plant community species composition and the habitat factors,analyzing the characteristic of the habitat of the region,the floristic characteristics of the different species composition and diversity of habitat gradient,and the correlation of habitat factors and species diversity.The results show that:(1)A total of 300 species of 208 genera of 89 families of vascular plants were recorded,including 280 species of 190 genera of 76 families of angiosperms,7 species of 6 genera of 5 families of gymnosperms and 13 species of 11 genera of 7 families of ferns.In terms of plant family composition,the few-species family(2-5)is the most abundant,with 40 families.In the composition of the genus,the largest number of single species is 153 genera.In terms of floristic composition,there are 23 families in the world.Tropical and subtropical distribution has 41 families;There are 24 families in the temperate zone,The tropical distribution occupies a large advantage,and the temperate distribution and the world distribution occupy roughly the same proportion.There are 17 genera in the world;There are 102 genera in tropical distribution.There are 88 genera in the temperate zone.In the distribution of the genus,the tropical distribution is slightly higher than the temperate distribution,the world distribution of the least proportion.(2)the slope gradient,the habitat characteristics reflected by the slope from the environmental factors are as follows: 1)In terms of water conditions,the habitats in the river valley,mountain peak and ridge are generally arid,while the habitats on the upper,middle and lower slopes are relatively humid.2)On the soil nutrient condition and under three slope positions,which the content of the soil chemical properties more homogenous,soil layer is thick,soil nutrients are relatively good,various properties of ridge area difference is bigger,the top of the mountain and valley average chemical properties of soil is lower than other several slope,and the soil is shallow;3)in terms of light conditions,the peak,uphill,ridge and valley are well illuminated,while the intensity of light in the middle and downhill is relatively weak.Habitat differences between different slopes lead to certain differences in community types and species composition.The community types of mountain tops and ridges were mainly coniferous and hard leaved forests.There were more species with drought tolerance and like light,species like Pinus massoniana Lamb.and Quercus phillyraeoides A.Gary.The community types in the middle and lower slopes were mostly evergreen or deciduous broad-leaved forest.Species such as Choerospondias axillaries(Roxb.)Burtt et Hill and Celtis sinensis Pers.have a big advantage.The climate in the valley is hot and humid,and the soil is poor in water and fertilizer retention,only the transition between the downhill and the river valley has trees,The community near the river bank is mostly beach thickets,species such as Distylium dunnianum H.Lév.have a big advantage.(3)There was no significant difference in the Margalef index of tree layer in different habitats.The Margalef index of wood layer was significantly higher than that of middle,downhill and river valley,and significantly higher than that of uphill and river valley.The Margalef index of the herb layer showed that the peak was significantly lower than the middle,lower and valley,and the ridge was significantly lower than the middle slope.There was no significant difference in shannon-wiener diversity index of tree layer.Shannon-wiener index in shrub layer was significantly higher than that in valley and slope.The shannon-wiener index of the herb layer was significantly lower than that of the middle,downhill and valley.The Pielou index of tree layer was significantly lower than that of other slopes.There was no significant difference in Pielou index between shrub layer and herb layer.The Simpson index of tree layer was significantly higher than that of hilltop.The Simpson index of shrub layer was significantly lower than that of mountain peak.The Simpson index of the herb layer was significantly higher than that of the middle slope,the downhill slope and the valley.In the comparison of community overall diversity,the four indices of the ridge are significantly different from other slopes.Margalef index is significantly lower than other slopes except the ridge.Shannon-wiener index showed that the ridge was significantly lower than other slopes.Pielou index shows that the ridge and peak are significantly lower than other slopes.Simpson index shows that the ridge is significantly lower than other slopes and the peak is significantly higher than other slopes.(4)By analyzing the relationship between habitat factors and species diversity,it was found that slope position and disturbance degree had significant effects on species distribution in tree layer.Slope position,litter thickness,disturbance degree,soil organic matter,humus thickness,total nitrogen,slope and total phosphorus had significant effects on shrub species distribution.Litter thickness,total phosphorus,slope position,humus thickness,soil organic matter,light intensity,total nitrogen and slope had significant effects on herb species distribution.In the total community,slope position,disturbance degree,litter thickness and humus thickness had significant effects on the overall species distribution.Other factors also have different effects on different levels,but this effect is not significant.(5)Slope position and disturbance degree have significant effects on almost every level.As far as shi bingkarst is concerned,slope position and anthropogenic disturbance may be the main factors affecting the distribution pattern of species and play an important role in the maintenance of species diversity.Heritage site in the process of development of tourism,want to consider the impact of human disturbance,the scenic area planning and construction is not only to reasonable,to prevent damage to the ecological constructive destruction,also should consider factors for a long time,have enough perfect management mechanism to cope with the increasing number of visitors,reduce the influence of tourist behavior of vegetation and ecological environment,guarantee the sustainable development of ecological and economic development.