荒漠河岸林水盐梯度上植物功能性状格局与群落构建机制研究

Desert riparian forest in Tarim basin was be as the research objective. The distribution patterns of functional traits, functional diversities(α、β) of community multidimension(leaf, stem, root, seed,plant height) and different life forms along the soil water-salinity gradient, and their relationships between environment and space scales were investigated with combining the methods of community ecology, functional ecology and soil science. This research explored the response mechanisms of community functional traits, functional diversity to soil water-salinity gradient and environment driving mechanism, relationships of plant functional traits and trade-off strategy, and the main functional traits affecting functional diversity. At the same time, predicting the applicability of deterministic process and stochastic process of community assembly theory in desert riparian forest were explored with building null model, trait-gradient analysis, redundancy analysis. The relative contribution of the environment filtering and limiting similarity(interspecific interaction) of controlling the community functional traits change in community assembly process along the soil water-salinity gradient were analyzed with the internal and external factors. To illuminate the change rule of community functional traits and ecological strategy along the soil water-salinity gradient, and community assembly process, further to reveal the potential driving forces of plant ecological strategy and community assembly mechanism of desert riparian forest along the soil water-salinity gradient, and community evolution mechanism. In order to enrich the functional ecology of arid region and community assembly theory, and provide scientific theoretical basis for biodiversity conservation, vegetation restoration and reconstruction of degraded desert ecosystem in Tarim extreme arid region.

以塔里木荒漠河岸林为研究对象，采用样带法运用群落生态学、功能生态学与土壤学方法，研究水盐梯度上群落多维(叶、茎、根、种子)与不同生活型的功能性状、功能多样性(α、β)分布格局与空间尺度、环境的关系，结合群落特征、物种多样性探讨群落功能属性对水盐梯度的响应机理和环境驱动机制，功能性状间的关联、权衡与资源利用策略，及影响功能多样性的主要性状。通过构建零(随机)模型、性状梯度分析、RDA等方法，检验基于确定性过程、随机性过程的群落构建理论预测的适用性，结合内外因素分析水盐梯度上主导群落功能属性变化的环境过滤、限制相似性在群落构建中的相对贡献。阐明群落功能属性沿水盐梯度的变化规律与生态适应策略及群落装配过程，揭示水盐梯度上荒漠河岸林群落构建机制和生态策略变化的潜在驱动力及群落演化机制，充实干旱区功能生态学与群落构建理论，为塔里木极端干旱区生物多样性保护、植被恢复和退化生态系统恢复重建提供理论依据。

塔里木荒漠河岸林是保障绿洲生态安全的天然屏障，受全球气候变化与人为干扰逐年退化，拯救脆弱荒漠河岸林迫在眉睫。项目以新疆塔里木河上中游荒漠河岸林为研究对象，通过野外群落调查与植物、土壤样品采集化验及数据分析，阐明塔里木荒漠河岸林群落功能性状与其多样性格局动态、功能适应策略，及地下水埋深(土壤水分)是调控植物功能性状与植物-土壤养分循环的关键要素。揭示荒漠河岸林土壤缺氮少磷，植物生长主要受磷素限制，且水力路径长度(地下水埋深、树高)在调节株高、叶枝异速生长与枝叶量纲的标度关系方面的重要作用；荒漠植物通过枝叶性状的异速生长权衡与通过内稳态调节来改变自身养分利用策略与化学计量比，以小叶、低展叶效率来拓展生态幅，以保守型策略适应日益旱化的贫瘠荒漠环境，这增进对荒漠植物功能(策略)多样性驱动机制的认知。中性过程在荒漠河岸林群落构建中发挥着主导作用，且生态位过程(水分养分限制)与中性过程共同作用于荒漠植物群落构建过程，提出维持塔里木荒漠河岸林物种-功能多样性和生态系统功能的合理地下水埋深为4.5 m左右，生态管理中应注意土壤水分、磷的供应与活化及生境改善。这为预测全球气候变化对该区域未来植被影响、物种适应进化提供理论基础，也为荒漠河岸林保育复壮与生态功能提升提供科学依据。