高寒草地植物群落地上-地下净初级生产力权衡

Trade⁃off between aboveground and belowground net primary productivity of plant communities in alpine grassland

植物生产力分配和权衡是植物生态学研究中的热点,反映植物对环境的适应性,是了解植物响应全球气候变化的关键。青藏高原作为气候变化敏感区,研究其植物地上与地下部分权衡对了解高寒草地植被生存策略和生态系统可持续发展具有重要意义。目前,生物量分配调控机制已被广泛研究,但主要使用植物根冠比和地上-地下生物量比等方法来表征植物分配模式,缺乏考虑因植物生长周期导致的差异。使用青藏高原高寒草地103个样点的地上和地下净初级生产力数据,分析高寒草甸和高寒草原两种主要草地类型的地上-地下净初级生产力权衡关系。利用气候因素和土壤因素等相关数据,结合方差分析、相关分析、相对重要性分析和结构方程模型的方法,探究环境因素对两种草地类型地上-地下净初级生产力权衡的影响机制。研究发现:(1)高寒草甸的地上净初级生产力、地下净初级生产力和土壤养分含量显著高于高寒草原(P<0.05);(2)高寒草地植被生产力均向地下权衡(0.0199),且高寒草原(0.0354)的权衡值高于高寒草甸(0.0173);(3)结构方程模型发现,年平均降水量、土壤容重和土壤速效氮含量是影响高寒草甸生产力权衡的主导因子,而年平均温度和年平均降水量是影响高寒草原生产力权衡的主导因子。研究表明高寒草甸的生产力权衡主要受气候和土壤因素共同影响,而高寒草原主要受气候因素调节。研究为理解植物地上-地下生物量分配调控机制提供了新的视角和方法,对系统了解高寒草地生物量分配模式和准确预测高寒草地植被动态过程具有指导意义。

The allocation and trade-off of plant productivity are hot topics in plant ecology.They could reflect the adaptability of plant to the environment,and also are the key to understand the response of plant to global climate change.To study the trade-off between of aboveground and belowground of plants is crucial to understand the survival strategies of vegetation and the sustainable developments of alpine grassland ecosystem on the Qinghai-Tibet Plateau,where are more sensitive to climate change.At present,the driving mechanisms of biomass allocation have been widely studied.Plant allocation patterns are generally characterized by plant root-shoot ratio and aboveground-belowground biomass ratio.However,these mainstream methods probably ignored the fact that belowground biomass of vegetation are accumulated over many years.Using aboveground and belowground net primary productivity data from 103 sample sites of alpine grassland on the Qinghai-Tibet Plateau,this study analyzed the trade-off between aboveground and belowground net primary productivity of two main grassland types,alpine meadow and alpine grassland.The influence mechanism of environmental factors on the trade-off of aboveground and belowground net primary productivity of two grassland types was explored by using relevant data such as climate factors and soil factors,combined with variance analysis,correlation analysis,dominance analysis and structural equation model.The results showed that:(1)The aboveground net primary productivity(ANPP),belowground net primary productivity(BNPP),and soil properties of the alpine meadow were significantly higher than that in alpine steppe(P<0.05);(2)In general,the trade-off of plant net primary productivity in alpine grassland tend to belowground(0.0199),and the trade-off to belowground in alpine steppe(0.0354)was higher than that in alpine meadow(0.0173);(3)The structural equation model showed that annual mean precipitation(AMP),soil bulk density(SBD),and soil available nitrogen(SAN)were the dominant factors affecting the trade-off in alpine meadow,and annual mean temperature(AMT)and AMP were the dominant factors in alpine steppe.The research showed that the productivity trade-off of alpine meadow was mainly affected by climate and soil factors,while alpine grassland was mainly regulated by climate factors.The findings of our study will provide a new insight and statistical approach for understanding the allocation between aboveground and belowground biomass of plants.In addition,our study will contribute to comprehending systematically the biomass allocation model,and predicting accurately the dynamic process of alpine grassland vegetation.