洞庭湖荻-苔草群落交错带植被动态及影响因子——以北洲子洲滩为例

近年来,受全球变化及高强度人类活动的影响,洞庭湖湿地群落分布带不断下移,引发了人们对其湿地服务功能下降的担忧.以洞庭湖北洲子洲滩为例,采用野外样带调查和室内分析相结合的方法,对洞庭湖湿地荻-苔草群落交错带植被和环境特征进行研究,以期揭示荻-苔草群落交错带动态变化和影响其变化的关键环境因子.结果表明:土壤含水量随高程增加呈逐渐降低的趋势,土壤总碳、总氮、总磷含量和p H值在样带间差异显著,但土壤电导率和总钾含量在样带间无显著差异.各样带物种丰富度和香农指数随高程增加整体上呈先降低再增加的趋势.荻生物量随高程增加呈逐渐增加的趋势,而苔草生物量呈先增加后减少的趋势.典型相关分析表明,土壤含水量与二者生物量及群落丰富度、多样性间具有很好的相关性,表明土壤含水量是调控该群落交错带植被动态变化的关键环境因子.

Vegetation dynamics of Triarrhena sacchariflora and Carex sp. community ecotone and determining factors in Lake Dongting:A case study in the Beizhouzi lake-shore

In recent years, the vegetation distribution decreased significantly in Lake Dongting due to global change and intensive human disturbance, and has induced significant concerning about the decrement of service functions. In order to reveal the vegetation dynamics and its dominant influencing factors of Triarrhena sacchariflora and Carex sp.community ecotone, we took Beizhouzi lake-shore as an example, and investigated the vegetation characteristics and soil environmental characteristics in the ecotone of T. sacchariflora and Carex sp.community in the Lake Dongting based on belt sampling method and indoor measurement. The results showed that: soil moisture decreased significantly along with increment of elevation. Total carbon, total nitrogen, total phosphorus and pH had significant difference between these belts, while conductivity and total potassium displayed similar patterns. Vegetation species richness and diversity index decreased firstly and then increased along with elevation. Biomass of T. sacchariflora increased significantly along with elevation, while biomass of Carex sp.community exhibited increase firstly, followed by decrease with elevation. Canonical correlation analysis showed that soil moisture was significantly correlated with both biomass accumulation of T. sacchariflora and Carex sp., and vegetation species richness and diversity, indicating that soil moisture is the key dominant factor influencing vegetation dynamics in this ecotone.