Diversity Pattern Of Woody Plant Sexual System And Its Environmental Interpretation:Community To Region

Plant sexual system adopt different reproductive strategies to maintain the continuity of their populations and form a diversified distribution pattern.However,at the community and regional levels,the composition characteristics of the plant sexual system of forest community and the environmental factors driving the distribution pattern of the system are still unclear.Based on forest dynamic monitoring plots,woody plants were divided into monoecious,dioecious and hermaphroditic according to the presence or absence of functional pistils in flowers,study on the quantity rule and driving factors of woody plant sexual system from community scale and regional scale.The results are as follows:(1)In order to explore the quantitative characteristics of woody plant sexual system in temperate deciduous broad-leaved forest on community scale and its ecological relationship with environment,this study was based on the woody plant data of 5 hm2 forest community in temperate deciduous broad-leaved forest,the quantitative characteristics of woody plant sexual system in temperate deciduous broad-leaved forest and its ecological correlation with topographic factors were analyzed by using the methods of species diversity index,partial correlation analysis and partial variance decomposition.The results showed that among 93 species of woody plants,19 species(20.43%)were dioecious,20 species(21.51%)were monoecious and 54 species(58.06%)were hermaphroditic.Altitude is an important factor affecting the diversity index of monoecious,dioecious and hermaphroditic.The community-scale temperate deciduous broad-leaved forest has a large proportion of monoecious plants,and the results are consistent with the reproductive characteristics of temperate forests Diffusion restriction is an important ecological process affecting the woody plant community.(2)In order to study the variation characteristics of woody plant sexualsystem composition and its ecological relationship with the environment at different succession stages,this study was based on the woody plant data of four different successional forest communities,the composition characteristics,spatial distribution pattern and ecological correlation with topographic factors of woody plant sexual system in different successional stages were analyzed.The results showed that there were significant differences in the proportion of dioecious and monoecious species among plantation forest,twice-cut forest and once-cut forests,while the proportion of dioecious and monoecious species in old-growth forest was the same.Based on the completely random model,monoecious and hermaphroditic in different successional forest communities were clustered at the scale of 0 ~ 25 m,and dioecious plants were mainly clustered and randomly distributed.After exclusion of habitat heterogeneity,the distribution pattern of four different successional forest plot systems changed greatly under heterogeneous Poisson model.In the old-growth forest,the species richness of the plant sexual system was most affected by the average altitude and slope direction.Habitat heterogeneity may be the main reason that affects the spatial distribution of plant sexual system in different successional forest communities.(3)In order to explore the quantity change of woody plant sexual system along latitudinal gradient on regional scale and the degree of environmental influence on sexual system,this study is based on the woody plant data of dynamically monitored plots,the proportion of the plant sexual system in each forest dynamic monitoring plot was calculated,and the environmental factors affecting the distribution pattern of the plant sexual system were investigated by linear regression and SEM models.The results showed that the number of dioecious species was higher than that of monoecious species in low latitudes and that of monoecious species was higher than that of dioecious species in high latitudes.Latitude and annual mean temperature have great influence on species diversity of hermaphroditic.Annual mean temperature is the most important environmental factor affecting monoecious and dioecious.(4)In order to explore the habitat preference of plant sexual systems on regional scale and the ecological relationship between plant sexual systems and environmental factors in different climatic zones,the dynamic monitored plots were divided into three types: tropical,subtropical and temperate,as three different habitats,the network correlation diagram and torus-translation were used to test the habitat preference of plant sexual system from the perspective of community and species respectively NMDS and partial variance decomposition were used to explore the ecological relationship between intraspecific systems and environment in different climatic zones.The results showed that the distribution of plant sexual system in the three climatic zones was not random,monoecious preferred temperate zones,dioecious preferred tropical and subtropical zones.The main environmental driving factors of monoecious,dioecious and hermaphroditic were different in different climatic zones.Based on the woody plant data of forest dynamic monitoring plots at community and regional scales,this study explored the quantitative characteristics,spatial distribution pattern and ecological relevance to the environment of sexual systems at different scales,the results of this study will deepen the understanding of forest community structure,dynamics and related mechanisms from the perspective of plant reproductive characteristics,and provide theoretical basis for biodiversity conservation and species coexistence in forest communities of different scales.