太行山绿化工程油松人工林水源涵养服务形成过程与变化机理研究

Water conservation services of the Taihang mountain afforestation project have recently attracted much attention as the important carrier for the North China Plain and Beijing-Tianjin Area. This project, taking Pinus tabulaeformis plantation as the researching objective due to its pivotal role in the Taihang mountain Greening, using the method of conversion from space to time, closely revolves the key scientific issue of the forming process and changing mechanism of the water conservation services of Pinus tabulaeformis plantation. Two issues will be addressed by this project. Firstly, based on site-specific observation and experiment, the formation and change of of water conservation services at different succession stages of Pinus tabulaeformis plantation at sample plot scale will be clarified. And then, through analyzing the influencing process of Pinus tabulaeformis plantation restoration on vegetation cover and soil physical properties, and also the relationship among vegetation and soil properties change, water-holding characteristics, as well as the surface runoff yield, the forming process and changing mechanism of Pinus tabulaeformis plantation restoration on water conservation services will be revealed. In addition, spatial-temporal evolution of the water conservation services of Pinus tabulaeformis plantation at basin scale will be explored using InVEST model, by combining remote sensing data with information from field plots, and its water conservation services effect will also be discussed through sensitivity analysis. This study will be helpful to enhance the understanding of the formation and change mechanism of ecosystem services of the Taihang mountain afforestation project, and can also provide some scientific basis for the ecological construction and management policies of the Taihang mountain.

太行山绿化工程作为京津地区和华北平原水源涵养服务的重要载体，其水源涵养服务效应备受关注。本项目选择对太行山绿化工程具有举足轻重作用的油松人工林为研究对象，围绕油松人工林水源涵养服务形成过程与变化机理这一关键科学问题，采用“空间分布替代时间演替”的思想，重点开展（1）基于野外定位观测与试验，从样地尺度阐明太行山绿化工程油松人工林水源涵养服务的形成过程与变化规律；辨识油松人工林林分表征参数与其持水特性和产水量间的复杂关系，揭示其水源涵养服务形成演变的主导因子、作用机理；（2）结合样地和遥感数据，借助模型模拟，从流域尺度阐明太行山绿化工程油松人工林水源涵养服务的时空演变，并通过敏感性试验辨识其水源涵养服务效应。本项目有助于提升对太行山绿化工程生态系统服务形成与变化机制的认识，为太行山生态建设管理提供依据。

太行山绿化工程作为京津地区和华北平原水源涵养服务的重要载体，其水源涵养服务效应备受关注。项目以绿化工程主要树种油松为研究对象，围绕油松人工林水源涵养服务形成过程与变化机理这一关键科学问题，采用“空间分布替代时间演替”的思想，结合定位实验、野外调查、遥感监测以及模型模拟多种手段，阐明油松人工林水源涵养服务的变化过程与规律，揭示其水源涵养服务形成变化的影响因素与作用特征，解析太行山绿化工程油松人工林水源涵养服务效应。结果表明：（1）随着恢复年限增加，油松人工林胸径、基径、树高、土壤粉粒与粘粒含量、含水量、碱解氮含量增加，而冠幅、土壤有机质、速效钾、砂粒含量以及容重减少，各表征指标间呈现显著的相关关系；（2）油松人工林林冠截留率与降水量呈现对数函数关系，冠层最大持水量与有效拦蓄量随恢复年限增加而减小，但枯落物层最大持水量与有效拦蓄量表现出先增加后减小的规律，这与枯落物储量和结构有关；（3）油松人工林恢复过程中土壤水分供给能力呈现先增加后降低的特点，土壤最大持水量表现为33a油松人工林>45a油松人工林>49a油松人工林。总体上，土壤层是油松人工林生态系统综合持水量的最主要界面，约占总持水量的90%以上，土壤持水量、入渗率与土壤养分、水稳定性团聚体及微团聚体含量密切相关；（4）油松人工林恢复到一定阶段，>2mm粒级的土壤水稳性团聚体含量下降，土壤水稳性团聚体D和PAD波动增加，土壤黏粒会促使小粒级土壤水稳性团聚体的形成，而有机质、速效磷、速效钾、砂粒等能够促进小粒级土壤水稳性团聚体向大粒级转化，从而提高土壤团聚体稳定性；（5）0.25~0.05mm粒级土壤微团聚体含量随着油松人工林恢复先增加后减少，而<0.02mm粒级土壤微团聚体含量先减少后增加，不同恢复年限土壤微团聚体D与MWD、GMD及PCM显著相关，而且与碱解氮和全磷含量相关紧密；（6）模型模拟显示，过去30年大沙河流域产水量有所减少，气候变化是流域产水量减少的主要驱动因素，而土地利用及人工林建设在一定程度上弥补了气候变化的影响。本研究有助于提升对绿化工程生态系统服务形成与变化机理的认识，为太行山生态建设以及区域可持续发展提供强有力的科学支撑。