滇西北高原湿地景观变化与人为、自然因子的相关性

人为活动的干扰与自然因子的变化共同作用于湿地生态系统,但两者对湿地生态系统作用的贡献率存在差异,目前尚缺乏进一步的研究。本研究基于面向对象分割和目视解译相结合的技术方法,研究了滇西北高原典型湿地纳帕海汇水区内28年来(1987—2015年)的湿地类型、分布及其空间格局的变化特征,并探讨其与当地人为活动的干扰(主要社会经济发展指标)、自然因子(主要气候因子)之间的相互关系。结果表明:(1)湿地总面积共计减少2456.46 hm~2,其中,原生沼泽、沼泽化草甸和草甸面积分别减少了1152.07,1257.72,202.74 hm~2,湖泊面积增加了156.07 hm~2;(2)湿地景观多样性发生显著变化,其中,斑块数量(NP)由1987年的221增加到2005年的299,随后减少到2015年的260;香农多样性指数(SHDI)由1987年的1.81增加到1999年的1.84,随后减少到2015年的1.75;聚集度指数(contagion index)由1987年的52.82减少到1999年的52.02,随后增加到2015年的53.49;(3)湿地分布面积和香农多样性指数与第一、二、三产业值,以及年均温度呈负相关,与降水量呈正相关;斑块数量、聚集度指数均与第一、二、三产业值,以及年均温度呈正相关,与降水量呈负相关;(4)社会经济发展主要指标对湿地面积和景观多样性指数变化的解释度为63.50%,气候因子对其的解释度为36.50%。整体上,人为活动的干扰是导致该区域湿地不断萎缩、景观多样性改变的关键驱动力。减缓人为活动对湿地生态系统的过度影响,是当地保护湿地资源、维护湿地生态功能的关键。

The correlations between wetland landscape and social-natural factors on Northwestern Yunnan Plateau

Interference from human activities and changes in natural factors work together to co-affect wetland ecosystems, but the different rates of their contributions to wetland ecosystems still lack adequate research. This research studied variations of the types, distributions, and spatial patterns of wetlands over 28 years, from 1987 to 2015, in the water catchment area of Napahai watershed, Northwestern Yunnan plateau, based on the methods of object-oriented segmentation and visual interpretation. The study also explored the interrelationships between wetland variations and human activities (i.e., socio-economic development indicators) together with natural factors (i.e., climatic factors). The results showed that (1) the total wetland area was reduced by 2456.46 hm², out of which the primary swamp, swamp meadows, and meadows were reduced by 1152.07, 1257.72, and 202.74 hm², respectively, and lake area increased by 156.07 hm². (2) The diversity of wetland landscapes changed over the years. Specifically, the number of patches (NP) increased from 221 in 1987 to 299 in 2005, and then decreased to 260 in 2015; the Shannon diversity index (SHDI) increased from 1.81 in 1987 to 1.84 in 1999, and then decreased to 1.75 in 2015; the contagion index decreased from 52.82 in 1987 to 52.02 in 1999, and then increased to 53.49 in 2015. (3) Wetland distribution area and SHDI were negatively correlated with the three industry values and mean annual temperature, and they were positively correlated with mean annual precipitation. However, unlike wetland distribution area and SHDI, NP and contagion index exhibited positive correlations with the three industry values but negative correlations with mean annual precipitation. (4) The main socio-economic development index contributed 63.50% of the variations in the wetland area and landscape diversity index, while climatic factors contributed 36.5%. Overall, the study showed that disturbance by human activity is the critical driving force for shrinking wetlands and landscape diversity changes. Thus, mitigating the excessive impact of human activities on wetland ecosystems is the key to protect the resources and maintain the functions of wetland ecosystems.