摘要
根据多年的气象资料和PDSI(Palmer Drought Severity Index)指数数据以及干旱年份(2002年)的水文资料,分析了南四湖区域气候变化的特征和干旱背景,并利用干旱年份的5景Landsat卫星遥感数据,计算了研究区的归一化植被指数(NDVI)和修正的归一化水体指数(MNDWI),并作为湿地对干旱响应的特征指标,研究了2002年南四湖湿地干旱特征,揭示了湿地对于极端干旱事件的响应特征,着重分析了干旱对湖泊湿地植被的影响,并讨论了极端干旱对于湖泊湿地生态系统和景观格局变化的影响。得到以下结论:①近60多年来南四湖湿地增温趋势明显(R2=0.21,P=0.0002),干旱趋势不显著。2002年是南四湖湿地自1951年以来降水最少年份,也是严重干旱年份(PDSI<-3);②干旱导致湿地水面持续减小,湿地植被NDVI和植被面积存在先升高后降低特征。在受到轻微干旱时,湿地植被NDVI略有增加;当发生中度和严重干旱时,湿地植被NDVI急剧下降,且小于多年平均值;③从空间格局看,2002年10月份南四湖中的南阳湖、独山湖和昭阳湖干涸见底。湿地干旱初期,随着水位下降植被向湖心扩展,湿地NDVI上升;而后随着湖盆出露和干旱加剧,植被开始由湖周边向湖心不断死亡,NDVI下降;④极端干旱事件对湿地生态系统和景观格局有显著影响。因此,进行景观格局年际变化分析时需要格外重视干旱等极端气候事件短时间内对湿地景观格局的影响。
Based on meteorological data,PDSI index data and hydrological data from a drought in2002,characteristics of climate change and drought at Nansi Lake were analyzed. As indicators of wetland responses to drought,NDVI and MNDWI were calculated by five Landsat remote sensing images in 2002. Characteristics of the wetland under extreme drought events were revealed,especially the impact of drought on vegetation,the effects of extreme drought on lake wetland ecosystems and landscape change. We found that a warming trend is clear but the drought trend is not significant for the Nansi Lake wetland by 60 years. The year 2002 was not only the year of least rainfall since 1951,but also a severe drought year(PDSI<-3). Drought induces a gradual decrease in surface water over the wetland,and the NDVI and vegetation area increase at beginning and then reduce. During minor droughts,the NDVI increases slightly. During moderate and severe droughts,the NDVI sharply declines and is lower than the average of many years.Nanyang Lake,Dushan Lake and Lake Zhaoyangall dried up in October. NDVI rises with the decline in water levels and vegetation expansion to the center of the lake at the beginning of the drought;the NDVI declines with further deterioration of the drought. These data show that severe drought events have a significant impact on wetland ecosystems and landscapes and we should pay extra attention to the impact of drought and other extreme weather events on wetland systems.
出处
《资源科学》
CSSCI
CSCD
北大核心
2014年第7期1519-1526,共8页
Resources Science
基金
教育部人文社会科学研究青年基金项目:"南四湖湿地生态系统服务时空演变与调控研究"(编号:12YJCZH120)
中国科学院战略性先导科技专项项目(编号:XDA05050602)
