长江中游农区洪涝灾害后鼠类数量动态

POPULATION DYNAMICS OF RODENTS AFTER FLOOD IN MIDDLE REACHES OF THE YANGTZE RIVER

1998年至2001年在湖南安乡对洪灾后的啮齿动物数量进行了监测,并以正常区为对照;与此同时,也对曾遭受过洪灾的其它地区进行了对比调查.调查发现,虽然洪灾对啮齿动物的种群影响很大,但其数量回升速度较快,退水半年左右,种群数量就会超过未发生洪灾的相邻地区.主要原因是洪灾使害鼠的生态压力减少,如害鼠数量大幅减少,而食物相对丰富,栖息空间相对较大以及天敌的数量减少等,从而使残存鼠和迁入鼠的数量得以迅速回升.洪灾后鼠密度回升到很高的地区,即使进行大面积的化学防治降低鼠密度后,其回升速度也不同于正常地区,同样具有快速反弹的特征.

Rodent population monitoring in flooded farmlands in the middle reaches of the Yangtze River was carried out during 1998-2001. The census was conducted in Anzao polder of Anxiang County in Hunan Province, where the dike burst in 1997 and vast farmland was flooded for three months. The monitoring data after the flood in 1998 indicated that most of the rodents were killed by flood. However, the rodent population increased rapidly after the flood. The rodent population was much higher than that in unflooded land half a year after flood. Census data of other area in the middle reaches of the Yangtze River also showed that the rodent population was usually much higher than that in adjacent unflooded land after flood. Another phenomenon was that the increases of rodent population were different in flooded and unflooded land after application of rodenticide. The population in flooded land also increased faster than that in adjacent unflooded land after the application of rodenticide. It was considered that the reason for fast increase of rodent population after flood was that the nature enemies of rodents were killed during the flood. Moreover, the food and habitats for rodents after the flood were relatively abundant. Fig 4, Tab 2, Ref 15