古尔班通古特沙漠南缘固沙植被斑块格局对降水脉动的响应研究

One challenge facing recovering and stabilizing sand-binding vegetation eco-system is that the understanding of mechanism on precipitation response to vegetation patches pattern in the desert is still weak. Not only is it showed up as deficient accumulation of desert ecosystem research, but also expresses as the theory and method are in the exploration stage. Under the background of desertification in arid region, the project considers sand-binding vegetation patch pattern as the study materials, and employs means of controlled test, belt-transects investigation, remote sensing inversion and numerical simulation, aiming at revealing the distribution rules of stabilizing sand-binding vegetation patches and soil water, elaborating precipitation impulse rules, resolving redistribution rules of soil water on the land surface, analyzing the influences of soil water on individual, community and patch pattern of vegetation, as well as describing the influencing relationship by parameters. We plan to analyze temporal and spatial changing characteristics and to discuss the mechanism on response of sand-binding vegetation patch pattern to precipitation impulse and the process. To carry out this study will increase research accumulation on mechanisms about response of sand-binding vegetation patch pattern to precipitation impulse, and supply reliable theory basis for vegetation restoration, ecological reconstruction and management.

沙漠固沙植被斑块格局对降水响应机制认识的薄弱已经成为恢复、稳定沙漠固沙植被生态系统的瓶颈。这种薄弱不仅表现在对沙漠生态系统研究积累不足，而且表现在理论和方法上仍处于探索阶段。在干旱区沙漠化的背景下，以古尔班通古沙漠（古漠）南缘固沙植被斑块格局为研究对象，采用控制试验、样带调查、遥感反演和数值模拟的方法，阐述降水脉动规律特征，解析土壤水在陆面再分配规律，揭示土壤水与固沙植被斑块空间格局及其分异规律，分析土壤水对个体、群落和植被斑块格局特征的影响且进行参数化表达，结合固沙植被格局时空变化特征，探讨固沙植被斑块格局对降水脉动响应的机理和过程。开展本项研究将增加国内固沙植被斑块格局和过程对降水响应机制方面积累，以期为干旱区的固沙植被恢复和生态重建及管理提供可靠的理论依据。

固沙植被斑块格局对降水响应机制是恢复、稳定沙漠的研究热点。在干旱区沙漠化的背景下，以古尔班通古沙漠南缘固沙植被斑块格局为研究对象，采用控样带调查、遥感反演和模型模拟的方法，阐述降水脉动规律特征，解析土壤水在陆面再分配规律，揭示土壤水与固沙植被斑块空间格局及其分异规律，分析土壤水对固沙植被斑块格局特征的影响，结合固沙植被格局时空变化特征，探讨固沙植被斑块格局对降水脉动响应的机理和过程。近55年降水量处于递增趋势(8 mm•10a-1)，中等量级( (5-10]mm、(10-15]mm)降水增加明显(3mm•10a-1)，夏季(0.3mm•a-1)、冬季(0.2mm•a-1)和春季(0.2mm•a-1)降水增加明显。降水对固沙植被演化具有明显正效应(r=0.458～0.561)，尤其是夏季大降水事件(r=0.439～0.476）影响深根系植被，春季小降水事件影响短命植被(r=0.367～0.612)。夏季高温对固沙植被生长具有负效应(r=-0.337～-0.387)，而生长季起(r=0.174～0.397)止(r=0.128-0.266）期低温对固沙植被生长具有正效应。固沙植被随降水脉动呈“恢复—退化—恢复”交替变化趋势，群落不断演替，但总体处于恢复趋势中。景观水平沙地植被破碎度处于增加趋势，中、高盖度植被的优势地位和连通性增强，植被斑块向沙漠腹地东北方向扩张。降水脉动对土壤水有明显正效应。个体尺度上土壤水在水平和垂直方向存在不同程度的分异。补水期固沙植被对表层(0-40cm) 土壤水空间格局约束，耗水期固沙植被对深层(40-100cm)土壤水空间格局约束。土壤水大尺度上受降水控制，在小尺度上受地形、植被和生物结皮控制。降水增加，固沙植被分布呈丘间地(固定沙丘)-丘间地、丘坡(半固定沙丘)-顶部和坡部(流动沙丘)，植被斑块大小—频率分布呈由截断幂函数向幂函数偏移分布。固沙植被斑块通过调整斑块大小分布策略来适应不同环境特征，239.46±101.62m2以上大斑块锐减，流动沙丘开始向裸地演化，固沙植被生态系统奔溃。为干旱区的固沙植被恢复和生态重建及管理提供可靠的理论依据，对理解干旱区固沙植被格局响应气候变化具有重要理论意义。