植被混凝土生态防护工程岩面-基材-植被养分循环研究

Degradation of slope ecological protection engineering is due to poor nutrient circulation in the ecosystem. According to the whole line of “mastering regulation, revealing mechanism, proposing strengthening method and evaluating efficacy”, this project takes vegetation-concrete as research object to study mechanism and promoting method of rockface-substrate-plant nutrient circulation. Through conducting controlled experiments, analyzing the biomass distribution and the biomass dynamic changes in the plant roots, stems, leaves and litter of the typical grass irrigation plant, circulation rules of nutrients within the plant and its contribution to the nutrient use efficiency in ecological protection engineering could be explained. The project establishes the rockface-substrate-plant nutrient circulation compartment model, selects and builds nutrient circulation parameters. According to monitoring data, impact of nutrient circulation process on microbial properties of the substrate and environmental factors, such as rainfall, slope, lithology, season and year will be identified. By evaluating situation of nutrient circulation, starting from improving the level of available nutrients in substrate, the formula and dosage of functional microbial agents can be defined. Therefore, the study provides explanation for function degradation of ecological protection engineering in theory and supports for elevating project sustainability in application.

边坡生态防护工程出现功能退化的实质是生态系统内养分循环不畅。项目融合土壤学与植物学理论，按照“掌握规律→揭示机理→提出调控方法→评价功效”的整体思路，以植被混凝土生态防护为对象，开展岩面-基材-植被养分循环机理与调控方法研究。通过控制性实验，分析典型草灌植物根、茎、叶及其凋落物的生物量分布与养分浓度变化动态，阐明植物养分内循环规律及其对生态防护工程养分利用效率的贡献；建立岩面-基材-植被养分循环分室模型，遴选、构造养分循环特征参数；依据多样地监测数据，明确养分循环过程对降水量、坡度、岩性、季节、年份等环境因子和基材微生物特性的响应特征，揭示养分循环机理。开展各样地养分循环状况综合评价，从提升基材速效养分水平出发，确定功能微生物菌剂配方、施用量与施用时机，提出养分循环调控方法并评估功效。从而，在理论上为解释生态防护工程功能退化提供依据；在应用上为提升工程持续性提供支持。

重建生态系统的养分循环流通能力直接影响植被生态恢复工程的持续性，开展人工植被恢复后边坡生态系统养分循环监测和评价具有重要意义。本研究以植被混凝土边坡生态防护系统为研究对象，基于植被类型、坡度、降水量不同环境模式，从生态系统水平定量研究了不同环境模式下“植被-基材-岩面”系统养分循环特征及其协同护坡效应，综合评价了生态防护工程的健康状况。结果表明：（1）植被类型、坡度、降水量均影响植物生物量积累和养分转移存储状况且随季节变化明显，整体表现为提升积累。草灌结合、低坡度、高水分下植物生物量的累积存储相对较高。草灌结合模式和低坡度下植物全磷积累效果最优，而较高水分含量均有利于植物各养分元素的积累存储；护坡植物具有适应贫养环境的养分转移生态策略，转移率以钾元素的最高，且以纯草本、高坡度、低水量转移程度较大。（2）环境模式均可改良土壤结构，不同程度的改善了土壤理化性质和养分状况，提升改善效果以草灌结合、低坡度及适中降水量模式最优。植被、坡度、水分均是制约植被恢复进程的限制因子，合理选择配置可以加速扰动系统生态功能的恢复。（3）不同环境恢复模式均影响岩面养分的存储和释放，可改善岩面在植被恢复过程中的养分参与度，且养分储量为积累上升。植被混播、低坡度、适量水分较有利于岩面养分的积累供给。（4）环境模式均影响系统养分归还流通状况且随元素和季节变化明显，系统养分净输入量以全氮最高，全磷最低，整体分别以草灌结合坡、45°坡、10 mm降水坡的养分净输入最大。（5）植被混凝土技术可提高和改善边坡恢复系统的养分循环状况，促进系统生态功能及水土保持功能的恢复，系统养分状况处于良好的流通积累状态，可自我维持发展。（6）外源接种AM真菌对植物生长和基材理化特性有正面影响，植被混凝土防护技术与菌根技术互补协同。研究结果可有效指导实施针对性的生态调控及建立植被恢复监测评价的长效机制。