海南省松涛水库消落区植被恢复适宜物种的筛选及耐水淹机制研究

The screening of the suitable plant species is critical for the vegetation restoration in the water level fluctuation zone (WLFZ). The field investigations of riparian vegetation and the studies of seed germination of riparian soil seed bank are beneficial and effective methods to screen the majority suitable plant species. The studies on flooding tolerance mechanisms of riparian plant species are beneficial to elucidate the self-maintaining mechanism of the riparian vegetation, and provide the guidance for riparian vegetation restoration. The studies on suitable plant species screening and flooding tolerance mechanisms for vegetation restoration in the water level fluctuation zone of Songtao Reservoir in Hainan province will be performed based on the ecological, physiological and restoration ecological principle and methods. Firstly, some assumed suitable plant species can be selected from the results of the field investigations of riparian vegetation and seed germination of riparian soil seed bank. Secondly, the suitable plant species can be determined from those assumed species through the flooding tolerance test experiments. Finally, the flooding tolerance mechanisms of some suitable plant species possessed high ecological and economic values will be elucidated based on the studies of morphological growth, photosynthetic efficiency, activities of antioxidant enzymes, carbohydrate and polyamine metabolism, reactive oxygen species accumulation, and membrane lipid peroxidation level and so on. The flooding tolerance mechanisms help explain the self-maintaining mechanism of the riparian vegetation. This research intends to cope with the key scientific difficulties for vegetation restoration in the WLFZ of Songtao reservoirs, including lack of suitable plant species and low survival rate. At the same time, it will also provide certain technological sustainment and scientific instructions for the demonstration and popularization of the large area vegetation restoration in the WLFZ, especially for the WLFZ of large reservoirs located in the tropical and subtropical regions.

适宜物种的筛选是消落区植被恢复的关键，消落区植被调查、土壤种子库研究能有效筛选到大部分的适宜物种。适宜植物的耐水淹机制研究有利于阐明消落区植物群落自我维持机制，指导植被恢复。本项目利用植物生态生理学和恢复生态学的基本原理和方法，开展松涛水库消落区植被恢复适宜物种的筛选及耐水淹机制研究。项目首先从消落区植被调查和消落区土壤种子库萌发实验研究出发，根据生长型和表型推断出消落区植被恢复的适宜植物；然后对拟定的适宜植物进行水淹耐受性检验，最终筛选出消落区植被恢复的适宜物种。对有生态和经济价值的适宜植物在形态生长、光合效率、抗氧化酶活性、碳水化合物、多胺及活性氧积累、膜脂过氧化水平等方面开展耐水淹机制研究，阐明消落区植物群落自我维持机制。研究成果可解决松涛水库消落区植被恢复中适宜物种缺乏、成活率低的关键科学难题；为热带亚热带地区大型水库消落区植被恢复大面积示范、推广提供技术支撑和科学指导。

适宜物种的筛选是消落区植被恢复的关键；适宜植物的耐水淹机制研究有利于阐明消落区植物群落自我维持机制。松涛消落区植被调查结果显示水库消落区共有维管植物40科101属115种，有利于适宜物种的筛选。消落区土壤种子库蕴含的基本为一年生草本植物，不能为适宜物种筛选提供实质性帮助。结合植被调查、文献分析以及海南本地情况，该项目选择乌墨、降香黄檀、水翁、芒果、油茶、桑树、美洲黑杨等木本植物作为研究对象，在形态生长、光合效率、氧化还原平衡等方面开展了耐水淹机制方面的研究；并且分别对降香黄檀、乌墨、桑树开展了水淹胁迫下的代谢组、转录组及蛋白质组学方面的相关研究。研究结果表明：1）降香黄檀、水翁、乌墨、桑树、美洲黑杨都具备较强的耐水淹能力，尤其是水翁和乌墨；2）外源亚精胺、脱落酸能够提高油茶和水翁的水淹耐受性；3）经历130 d水淹的降香黄檀完全成活；代谢组学分析表明降香黄檀幼苗受6 d水淹的差异代谢产物有113种，其中61种上调，52种下调。显著大幅度上调的为黄酮类化合物、苯丙素和原花青素A1等；4）转录组学析表明在经历100 d的水淹的乌墨叶片中共鉴定出708个差异基因，其中570个上调，138个下调。差异基因在植物-病原体互作、苯丙素生物合成、光合作用等KEGG通路上显著富集；5）蛋白质组学分析表明经历40 d半淹的桑树雌、雄株中分别有113和158个差异表达蛋白，其中有54个和91个蛋白分别在雌、雄植株中表达上调；这些差异蛋白主要参与能量生产与转化、碳水化合物运输代谢、次生代谢物的生物合成、信号传导、防御机制反应等途径；6）美洲黑杨对水淹胁迫具有较强的耐受性，但对盐钙胁迫较为敏感；钠钙充足情况下，水淹胁迫能显著刺激钠离子的吸收，但对钙离子的吸收促进作用不明显。该项目的研究成果较好地揭示了几种木本植物的水淹适应特征，可为降香黄檀、乌墨、水翁在热带地区消落区植被恢复的应用提供科学指导。