乌裕尔河-双阳河流域湿地景观格局演变及其驱动机制

Landscape pattern evolution of wetland and its driving mechanism in Wuyuer-Shuangyang River Basin

明确湿地格局演变特征与驱动机制是开展湿地管理与保护工作的重要前提。利用1980—2015年7期土地遥感解译数据,运用空间分析、景观指数、转移概率矩阵和增强回归树模型定量分析乌裕尔河-双阳河流域湿地格局演变特征与驱动机制。结果表明:(1)1980—2015年间湿地面积持续减少,减少了738 km^2,较1980年减少了16.43%;沼泽地占湿地的75%以上,面积也持续减少。1990—1995年是湿地面积减少速率最大的时段。(2)1980—2015年间湿地景观变化趋势为最大斑块的优势地位降低,破碎度加剧,且空间分布趋于离散,连通性减弱。沼泽地的景观变化特征与湿地相似,而水域与之相异。(3)1980—2015年间湿地损失集中分布在乌裕尔河两岸、双阳河中游及流域尾闾,主要转出为水田、旱地、草地和盐碱地,总的转移概率约为20%。(4)气候因素是导致湿地损失的主要因素,贡献率达到50%。道路修建对湿地损失的影响范围约为1.8 km;高海拔会增加湿地损失的风险;耕地周围2 km的湿地易被开垦;自然保护区的建立有效遏制了湿地损失。未来湿地损失风险较大的区域为乌裕尔河中游、双阳河中下游及流域尾闾。

It is an important premise for wetland management and protection to clarify the evolution characteristics of wetland pattern and its driving mechanism. Based on the remote sensing interpretation data of seven phases from 1980 to 2015, the evolution characteristics and driving mechanism of wetland pattern in Wuyuer-Shuangyang River Basin were quantitatively analyzed by spatial analysis, landscape index, transfer probability matrix, and boosted regression tree model in this study. The results are as follows:(1) from 1980 to 2015, the wetland area continuously decreased 738 km^2 by a reduction of 16.43% and the marsh accounted for more than 75% of the wetland with the continuous decrease. In 1990—1995, the wetland area reduction rate was the largest.(2) From 1980 to 2015, the landscape change trend of wetland was the dominant position of the largest patch decreased, the degree of fragmentation increased, the spatial distribution tended to be discrete, and the landscape connectivity weakened. The change characteristics of the marsh were similar to those of wetland, while the change characteristics of waters were different.(3) From 1980 to 2015, the wetland loss was mainly distributed on both sides of Wuyuer River, middle reaches of Shuangyang River, and the tail of the basin, which was mainly transformed into paddy field, dry land, grassland and saline-alkali land, with a total transfer probability of about 20%.(4) The climatic factors were the main factors leading to the loss of wetland, with 50% contribution rate. Precipitation was negatively correlated with wetland loss, and its impact was greater on wetland loss when annual precipitation was less than 450 mm. There was a positive correlation between temperature improvement and wetland loss, and its impact was greater on wetland loss when temperature improvement exceeded 1.4 ℃. The impact of road construction on wetland loss was within 1.8 km. The high altitude increased the risk of wetland loss. Wetlands within 2 km around cultivated land were easy to be reclaimed but the establishment of natural reserves effectively curbed the wetland loss. The areas with high risk of wetland loss in the future are the middle reaches of Wuyuer River, the middle and lower reaches of Shuangyang River and the tail of the basin.