河溪水文地貌异质性与物种多样性耦合机理研究

As river hydro-geomorphological heterogeneity provide basic habitats for organisms survival, it is the foundation of riverine biodiversity. Human activities lead to the serious degradation of river habitat, so we need take steps to repair river ecological status. At present the improvement of hydrogeomorphic heterogeneity is an important means of recovery biodiversity, also is one of the main purpose of river ecological restoration. Therefore it is particularly important to study the role of hydrogeomorphic heterogeneity played in the maintenance of the diversity of benthic organisms. This research will focuses on the Chishui river basin and Guijiang river basin, including micro habitat, reach, functional process zone, watershed and between watershed five different space scales. Increase perspectives of the functional group and functional diversity, and carry out benthic diatoms, macroinvertebrate diversity distribution pattern and hydrological landscape heterogeneity research pattern relevance, analyzing the relative contribution of uncertainty factors and random factors in community construction, focusing on the role of hydro-geomorphological heterogeneity. Reveal the coupling mechanism between hydrological geomorphological heterogeneity and the biological diversity. Provide ecological basis for river ecosystem restoration, monitoring and ecological evaluation, to solve the problem of lacking theoretical basis for ecological restoration. And so as provide scientific basis to alleviate the deterioration of river ecological, help coordinate water resources, social, economic and ecological environment relationship, with important scientific and practical significance.

河流水文地貌异质性为生物提供丰富的生存空间，是河流生物多样性的基础。人类活动导致河流生态状况恶化，急需采取修复措施。目前改善水文地貌异质性是河流生态修复的主要目的之一，也是恢复生物多样性的重要手段。因此研究水文地貌异质性在底栖生物多样性维持中所起的作用显得尤为重要。本研究拟在赤水河和桂江流域，从微生境、河段、功能过程区、流域到流域间5个不同空间尺度下，开展着生硅藻、底栖动物多样性分布格局与水文地貌异质性格局的关联性研究。在物种多样性的基础上，增加功能组和功能多样性的视角，辨析确定性因素和随机性因素对底栖生物群落构建贡献的相对大小；重点研究水文地貌异质性在其中的作用；揭示水文地貌异质性和生物多样性的耦合机制。本项目预期为河流生态修复及监测评价提供生态学依据，解决河流生态修复理论依据匮乏问题，有助于缓解我国河流生态系统的恶化趋势，协调水资源、社会、经济和生态环境的动态关系。

结合群落中性理论，对赤水河着生硅藻、底栖动物物种-多度格局进行检验，以解释其群落物种分布格局和生物多样性的维持机制。主要开展了以下研究：①分区域开展了着生硅藻、底栖动物多样性分布格局机理研究；发现赤水河着生硅藻和底栖动物中性理论的检验中少数区域及部分指标存在着差异，中性模型能够较好地预测6种不同空间区域中的着生硅藻、底栖动物群落的多样性分布格局。②分功能组对着生硅藻、底栖动物多样性形成机理进行了检验；由于3种不同的检验方法和区域在对赤水河底栖动物各功能组中性理论的检验中预测值和观测值存在较多差异，中性模型不适合预测着生硅藻、底栖动物功能组的多样性分布格局。③选用描述种-多度关系的生态位模型(断棍模型(broken stick model)、生态位优先占领模型(preemption model)、Zipf模型(Zipf model)、Zipf-Mandelbrot模型(Zipf-Mandelbrot model))、生物统计模型(对数正态模型(lognormal distribution model))以及中性理论模型（Volkov模型（Volkov model）、零和多项式分布模型（Zero-sum multinomial distribution model，ZMSD））, 对不同尺度下赤水河着生生物的物种数量关系进行了拟合研究，发现代表中性过程的ZMSD, Volkov模型差异较小，几乎同为最优模型；对数正态分布模型能模拟全部所选区域底栖生物的多度格局;断棍模型和生态位占优模型、Zipf模型和Zipf-Mandelbort模型拟合效果较差。④从不同尺度对着生硅藻、底栖动物多样性形成机理进行了检验；代表生态位过程的模型仅适合在微生境上拟合着生硅藻物种-多度分布，而这类模型能在微生境和河段两种尺度上拟合底栖生物物种-多度分布，随尺度增加中性过程的Volkov、ZMSD模型几乎同为最佳模型。综上所述，着生硅藻和底栖生物群落构建过程中，中性理论代表的迁移扩散等随机过程贡献较大，且随尺度增加，中性生态过程主导作用增强；对扩散能力较强的硅藻而言，尺度效应较弱。