美国西部国有森林破碎化模式及其管理含义

摘要

以美国西部3个著名的国家公园(黄石、洛基山和大峡谷)及其缓冲区为研究对象,以空间分辨率30m的3期美国国家土地覆盖数据库(National Land Cover Databases,NLCD 19922001 2006)为数据源,采用森林破碎化分析模型与景观指数相结合的方法刻画国家公园及其缓冲区内森林破碎化及干扰模式的时空差异,并有效分离导致森林破碎化的人为干扰和自然干扰贡献份额.结果表明:美国西部国家公园内森林因严格保护而破碎化程度较低且森林状态保持稳定,主要的干扰形式是自然干扰并伴有少量的城市土地利用类型的空间交互.而在缓冲区,由于存在相对宽松的森林经营活动森林破碎化程度较高,森林受自然干扰和人为干扰共同作用,其中农业土地利用扮演主要角色.这些差异主要归因于美国西部陡峻的地形、土地所有权及民众的生活方式.为了有效改善中国森林及国家公园的管理水平,可充分借鉴美国国家公园管理过程中的先进的经营理念、法律依据、管理机制、资金机制和监督机制等,并应在森林经营实践中确保森林保护政策有效执行.%A forest fragmentation model in concert with geospatial metrics was employed to characterize the spatio-temporal variability in forest fragmentation and disturbance patterns within three national parks (Yellow Stone, Rocky Mountains and Grand Canyon) and their transition zones in the western United States based on the triple-temporal national land cover databases (NLCD1992/2001/2006) in a spatial resolution of 30 meters. Contributions of anthropogenic and natural disturbances to fragmentation were effectively separated via the fragmentation model to highlight areas with high priority of conservation or remediation. Results showed that the forest in the national parks had a low fragmentation due to its rigorous forest conservation practice and the forest status remained relatively stable over time. Natural disturbances were identified as the major agent within the parks, and few interactions between forest class and urban land use were also observed. In contrast, in the transition zones, forests had a relatively high fragmentation thanks to the existence of relatively loose management activities, and the coexistence of natural and anthropogenic disturbances was responsible for forest fragmentation, especially, agricultural land uses played a critical role in interacting with forest class. These findings may principally attribute to its steep slopes of the western United States, tenure of lands and life styles of the local residents. To effectively manage China ' s forests and national parks, the advanced management philosophy, legislative authority, management mechanism, and financial surveillance mechanisms of the national parks in the western United States should be used as references. More importantly, the forest protection policies should be put into effect forcefully during the practices of forest management.