采用偏最小二乘回归方法估测森林郁闭度

以遥感数据与森林资源一类清查数据为基础,探讨了用Bootstrap方法筛选最优郁闭度估测变量,用偏最小二乘回归方法建立模型估测森林郁闭度的可行性.结果表明：无论是用所有变量构造的模型还是用所选最优变量构造的模型,郁闭度估测的相对偏差在5%左右.筛选出的最优变量与其他地区的研究结论差异很大,说明除了筛选方法,地带性植被和地形地貌的不同也会造成估测郁闭度最优变量的差异.

An approach to the ecological rehabilitation modes of Mentougou District in Beijing

Ecological rehabilitation was previously emphasized on the restoration of natural ecosystem, with the stress on the recovery of damaged ecosystem to primary ecosystem via various techniques and means, but nowadays, it integrates the restoration of natural ecosystem and the construction of artificial ecosystem. The conjugated ecological rehabilitation based on complex ecosystem theory is to rehabilitate the damaged ecosystem structure, function and process, and to construct and maintain the ecosystem to provide human with ecosystem services. Taking the Mentougou District in Beijing as an example, a comparative study was made on the three modes of ecological rehabilitation, i. e. , gradual ecological rehabilitation based on realistic ability, ecological rehabilitation based on government dominancy, and conjugated ecological rehabilitation based on complex ecosystem theory. Scenario analysis indicated that conjugated ecological rehabilitation could achieve maximal ecological and social benefits with least socio-economic costs.