| Plant diversity is an ecological combination formed by the interaction of plants with other organisms and the environment and related ecological processes.Comprehensive research on the diversity of species and functional traits helps to better understand the changing law of plant diversity.Karst ecosystem diversity is an important part of global ecosystem diversity,which maintains the structure and function of terrestrial ecosystem.So far,the understanding of the plant community characteristics and plant diversity pattern in the Karst area of southwest China is still very limited.According to the distribution law of karst forests in southwest China,this study selected Maolan,Sanshiliunong-Longjun,and Nonggang,three karst forests with relatively well-preserved nature reserves for investigation.15 plots(20m×20m)were established in these three protected areas,and a community survey was conducted.Through the analysis of community species ? diversity,species ? diversity and functional diversity to characterize the change of plant diversity.In this paper,seven kinds of functional characters,including chlorophyll content,leaf area,leaf size,specific leaf area,leaf dry matter content,leaf tissue density and wood density,were selected to explore the latitude pattern by analyzing the correlation between the functional characters and the law of change with latitude.This paper also uses Pearson correlation analysis method to analyze the relationship between the community species diversity index and the functional diversity index,to explore the change rule of plant diversity with latitude,so as to analyze the latitude pattern of plant diversity and functional properties in the southwest karst forest community.The results of this study attempt to provide guidance and scientific basis for community construction,vegetation restoration,and forest biodiversity protection in karst areas.The main results of this study are as follows:(1)There are 238 species of plants in Maolan Nature Reserve,belonging to 170 genera of 85 families;155 species of plants in Sanshiliunong-Longjun nature reserve,belonging to 124 genera of 82 families;232 species of plants in Nonggang nature reserve,belonging to 170 genera of 69 families.The latitudinal distribution of species composition shows that Maolan Nature Reserve is a mixed evergreen deciduous broad-leaved forest in the middle subtropical zone,with the most abundant species.The Sanshiliunong-Longjun nature reserve,which is in the transition from the south subtropical zone to the North tropical zone,is a seasonal rainforest with the least species.(2)The karst forest community structure in southwestern China shows that the dominant species have the most obvious latitude distribution pattern in the Sanshiliunong-Longjun reserve.Sanshiliunong-Longjun reserve has the highest abundance of dominant species in the arbor layer;Nonggang reserve has the highest abundance of dominant species in the shrub layer;Maolan reserve has the highest abundance of dominant species in the herbaceous layer.The diameter at breast height(DBH)class of the species,the DBH class of the arboreal community presents a single peak type,the whole community was young and middle-sized forest,the seedling reserve was sufficient,and the community renewal and development were good.In the DBH class of dominant species with woody plant important value?5,there are Cornus wilsoniana and Lindera communis in Maolan reserve,and their DBH class are close to normal distribution and single-peak type.There are 6 dominant species in the Sanshiliunong-Longjun reserve,in which the DBH class of Zenia insignis and Canthium horridum is discontinuous,the DBH class of Excentrodendron tonkinense is fluctuating,and the DBH class of Streblus tonkinensis is close to normal distribution,Diospyros siderophylla and Desmos chinensis are single-peak type.There are 3 dominant species in the Nonggang reserve,Deutzianthus tonkinensis DBH class is fluctuating,Dracontomelon duperreanum and Vitex kwangsiensis DBH class are close Normal distribution.(3)In the latitudinal pattern of species ? diversity,the overall community species ? diversity is Maolan>Nonggang>Sanshiliunong-Longjun reserve;in the vertical stratification community,the change rule is inconsistent,in the arbor layer and herbaceous layer,the species ? diversity of Nonggang reserve is the highest;in the shrub layer,the species ? diversity of Maolan reserve is the highest.In the latitude pattern of species ? diversity,the degree of species difference between communities is positively correlated with the degree of latitude difference.The species difference between Maolan and Nonggang reserve is the largest,and the difference between the Sanshiliunong-Longjun and Nonggang reserve is the smallest.Between the species diversity index and the latitude gradient,the overall species richness index and the Simpson index of the three protected areas are positively correlated,and the Jaccard index and Sorensen index are significantly positively correlated,but with the change of latitude,there is no regular correlation.The Pielou index in the arbor community was positively correlated with the species diversity index,and the species richness in the herbaceous layer community was positively correlated with the Simpson index.The species Jaccard index and Sorensen index showes a significant positive correlation with latitude gradient.(4)The correlation between the seven plant functional characters of karst forest community in southwest China is consistent.However,with the change of latitude,there are differences in the types of related functional traits.Among them,there are 7 pairs of correlated traits in Maolan reserve(2 pairs are significantly positively correlated,5 pairs are significantly negatively correlated),10 pairs of correlated traits in 36-Nong Longjun reserve(3 pairs are significantly positively correlated,1 pair is positively correlated,4 pairs are significantly negatively correlated,2 pairs are negatively correlated),and there are 17 pairs of related characters in Nonggang Reserve(9 pairs are significantly positively correlated,7 pairs are significantly negatively correlated,1 pair is significantly negatively correlated).In conclusion,the correlation between functional traits was consistent with latitude.With the increase of latitude,the content of chlorophyll,leaf area,leaf size and specific leaf area decreases gradually,and the dry matter content of leaf increases gradually.The density of leaf tissue and wood is the highest in Sanshiliunong-Longjun nature reserve.The latitudinal pattern of functional diversity,with the increase of latitudes,decreases gradually in both functional richness and functional evenness index.The functional dispersion is the largest in the middle latitudes and the smallest in the low latitudes.There is no correlation between the functional diversity indexes of karst forest communities in southwest China.(5)The relationship between species diversity and functional diversity of karst forest communities in southwestern China shows a certain regularity in latitude pattern.The Shannon-Wiener index,Simpson index,and Pielou index in the ? diversity of species are positively correlated with the functional richness index,and there is no correlation between the remaining indexes.The differences in species composition,structure,plant diversity and functional traits of karst forest communities in southwestern China increased with increasing latitude.Environmental factors caused by latitude differences,non-zonal factors caused by karst landforms,and disturbance factors all have varying degrees of influence on the community composition and structure,plant functional traits,and plant diversity of karst forests in southwest China. |
PDF Full Text Request