扎龙湿地生态环境变化及其对白鹤迁徙的影响

分析了1986-2002年扎龙湿地自然和社会生态环境变化及其对春季白鹤迁徙活动的影响.研究表明:在区域气候干旱化背景下,流域中上游水土资源的开发利用、大型工程建设等影响使扎龙湿地生态环境发生很大的改变,鸟类栖息繁殖的生境遭到破坏.近17年来,湿地总面积减少了21.33 km2,芦苇沼泽和明水沼泽面积分别下降6.14 km2和6.27 km2,湿地分布重心向西北方向偏移了771.1 m.沼泽斑块数量增加,平均规模缩小,大块沼泽湿地不断被蚕食,栖息地破碎化程度增大.保护区生态环境趋于恶化,珍稀水禽的栖息空间萎缩,取食条件变差,在扎龙湿地停歇的白鹤数量减少,停留时间缩短.1998年嫩江流域大洪水过后,连续3年严重干旱,2002年白鹤的数量锐减到仅126只.2002年以来大规模的生态补水使扎龙湿地生态功能得到一定恢复,迁徙停歇的白鹤种群数量明显增加,分布范围扩大.

Ecological environment change and its effect on Siberian White Crane migration in Zhalong Nature Reserve

The effect of wetland ecological environment change in Zhalong Nature Reserve on migration number and distribution of Siberian White Crane is analyzed.Based on remote sensing data and GIS technology,the landscape dynamic patterns of Zhalong wetland reserve during recent 17 years are obtained.Results show that the area of wetland has reduced 21.33 km2,of which lake and pond 8.92 km2,reed marshes 6.14 km2 and carex swamp 6.27 km2.The annual decreasing rate of the lake and pond is 0.51%,while the reedy marshes and carex swamp decrease 0.05 and 0.06 a.p.r.respectively.From 1986 to 2002,the number of marsh patch increases 29,lake and pond decreases 9,and average size of reed marshes and carex swamp patches shrunk.The shape of patch tended to be more irregular.Large area wetlands are gradually destroyed fragmentally.The centroid of wetland distribution has been moving to the northwest by 771.1 m.Due to the warmer and drier regional climate,together with intensive and irrational human activities including reclamation,water conservancy,road construction,discharge of industrial pollutants and fertilizer and reed fires,the ecological environment in Zhalong has been more vulnerable thereby the number of Siberian White Cranes decreased greatly.Since 2002,the complementing water projects have been implemented in the Zhalong wetland.With the ecological environment restoring,the population of the Siberian White Crane resting in spring tends to increase gradually.