Temporal And Spatial Characteristics Of Soil Water And Its Relationship With Plant Community In Tiantong Evergreen Broad-leaved Forest

The microclimate formed by specific microtopography and vegetation is often quite different from the regional climate.Therefore,the effect of microclimate on plant community will be different from that of regional climate,however,these differences are often neglected in community ecology.As a part of microclimate,soil water content may also vary with microtopography and vegetation in small scales,thus influencing plant growth and species distribution in forest.Owing to the lack of monitoring capacity,we still know little about the soil water characteristics caused by microclimate in subtropical evergreen broad-leaved forest,especially in Tiantong area.Based on the newly built soil moisture observation network in Tiantong forest dynamic plot,combined with the plant community survey data,microtopography data and precipitation data in Tiantong area,our study aimed to explore the variation of soil water in the forest and its relationship with microtopography and vegetation.Results showed that:(1)Microtopography have effects on soil water status,among which there is significant positive relationship between soil moisture and elevation in some months;(2)In the process of precipitation event,soil moisture and its variation under different microtopography are significantly different: soil moisture in high altitude is significantly higher than that in low altitude;soil moisture and its maximum rising rate in valley are significantly higher than that in ridge;(3)In small scale,soil moisture is also affected by biotic factors,among which soil moisture of evergreen tree species' distribution area is mainly significant negatively related to neighborhood density and the influence of heterospecific neighbors,as regard to deciduous tree species,soil moisture is mainly positively affected by relative growth rates of deciduous tree individuals while negatively influenced by neighborhood density and the influence of heterospecific neighbors;(4)Significant differences are detected in soil moisture status between the distribution areas of evergreen and deciduous tree species.Our study laid a foundation for the future researches which focus on the variation of environmental factors affected by forest microclimate and species distribution as well as coexistence driven by environmental factors.