云南省典型人工植被的时空演变及其生态需水与区域性干旱的关系

Extraordinary drought disaster occurred in five parties of Southwest China in 2010. In these drought areas social economy, production and life activities confronted great influence and the point that the drought was man-made disaster attracted a wide spread attention the main point of which was that planting eucalyptus and rubber trees might affect regional ecological environment. The idea has become a hot scientific problem discussed for a long time and explored untiringly in academic circles. In this project, basic theories and calculation methods of ecological water requirement were used from multi-crossed disciplines point. Technical means combined research on species scale and regional scale was adopted to explore temporal-spatial variation of the typical artificial vegetation in Yunnan province and relationship between its ecological water requirement and regional drought. These points were studied emphatically: ①historic evolution and distribution pattern of the typical artificial vegetation in Yunnan province; ②water consumption characteristics, water-saving and drought-resistance function, and soil and water conservation effect of the typical artificial vegetation; ③relationship between ecological water requirement of the typical artificial vegetation and regional drought. This study will reveal the typical artificial vegetation's practical ecological effect, and the correlation degree between temporal-spatial variation of its ecological water requirement and regional drought in Yunnan province. The results of this study may not only provide important scientific basis for identifying cause of regional drought and reasonable allocation of water resources, but also be profound guiding meaning to restoration and reconstruction of regional artificial vegetations.

2010年发生在我国西南五省区的特大干旱灾害不仅给灾区社会经济及生产、生活活动造成巨大影响，也使干旱成因"人祸"论（桉树、橡胶树种植对区域生态环境的影响）受到广泛关注，已成为学术界长期讨论和不懈探索的热点科学问题。本项目选择从多学科交叉的角度、应用生态需水基本理论与计算方法、采取物种尺度研究和区域尺度研究相结合的技术手段探索云南省典型人工植被的时空演变及其生态需水与区域性干旱的关系。重点研究：①云南省典型人工植被类型的历史演变及其分布格局；②典型人工植被的蒸腾耗水特性、节水抗旱性能和水土保持效应；③典型人工植被生态需水与区域性干旱的关系。该研究旨在揭示云南典型人工植被的实际生态效应及其生态需水的时空演变与区域性干旱的关联程度。研究成果不仅能为区域干旱成因的准确识别和水资源的合理配置提供重要科学依据，而且对于区域人工植被恢复与重建等具有深远指导意义。

选择西双版纳、楚雄州南华县等地为研究区，应用遥感技术手段研究了云南省典型植被的历史演变与分布格局。 以西双版纳为例，1976-2010年期间该地区植被演变研究结果显示：①研究期内研究区主要植被类型的数量波动。主要植被总面积未出现大幅起伏，其波动于1257984.18-1469874.90 hm2之间，年平均值为1366447.95 hm2，波动比例为-7.94%-7.57%；天然植被（热带雨林、热带季节性湿润林、热带季雨林、热带山地常绿阔叶林）面积先增加后减少，其占主要植被总面积的比例逐年下降，尤其是近期2个年份（2005、2010）该比例大幅下降；人工植被（橡胶林）的分布面积及其占主要植被总面积的比例均呈现逐步增加的变化趋势，尤其是近期2个年份（2005、2010）其面积和比例均大幅增加；人工植被（橡胶林）的建植不仅牺牲了天然植被364116.28 hm2，而且占据了其他土地类型34366.30 hm2。②研究期内研究区主要植被类型的分布演变。在研究期后期（1999年以后），天然植被在研究区不同区域（景洪市、勐海县、勐腊县）、不同海拔（<600 m、600-800 m、800-1000 m、1000-1200 m、1200-1400 m、>1400 m）、不同坡度（0-5°、5-8°、8-15°、15-25°、25-35°、>35°）、不同坡向（平地、阳坡、阴坡）的分布范围较研究期早期（1999年以前）均有缩减，而人工植被（橡胶林）在研究区不同区域、不同海拔、不同坡度、不同坡向的分布范围则保持快速扩增的态势。表明橡胶人工林建植已打破西双版纳地区原有的生态格局，将直接威胁区域生态安全和环境健康发展。需要尽快采取切实行动以遏制事态扩大化发展。 同样的研究显示：楚雄州南华县的植被演变也表现出相似的发展轨迹，即桉树人工林建植已破坏该地区原有的生态平衡，且危及区域生态安全和环境健康，亟待开展积极有效的自然保护行动。