北京城市扩展过程中耕地自然生产功能损失研究

研究目的：评估城市扩展过程中耕地的生产功能损失。研究方法：以北京为例，在遥感影像生成的1991、1997、2000和2004年4期土地利用数据支持下分析了耕地损失特征；利用气象数据结合桑斯维特纪念模型计算了作物生产潜力；从点、线、面和各区县角度分析了1991 — 2004年耕地损失对作物生产潜力的影响。研究结果：北京耕地由1991年的6158.9 km2减少为1997年的5598.9 km2，2000年的5121.4 km2以及2004年的4387.8 km2；由中心城市周围的面状耕地损失、次级城区周围的点状耕地损失和交通干线周围的线状耕地损失导致的作物生产潜力损失总量分别约为14.52×104 t、20.67×104 t和103.76×104 t；1991 — 2004年，北京各区县作物生产潜力损失总量约为223.6×104 t，其中密云区损失最大，门头沟区最小。研究结论：快速城市扩展过程中耕地生产功能损失明显，制定耕地保护策略时要兼顾耕地损失的数量、格局以及功能。

Production Capacity Loss of Farmland duringUrbanization in Beijing, China

The purpose of this paper is to assess the production capacity loss of farmland during urbanization in Beijing according to the crop potential productivity（CPP）, which is an important issue of farmland resource protection. Land use data of 1991, 1997, 2000, and 2004 obtained by remote sensing image were employed to calculate the farmland loss. Historical meteorological data were used in Thornthwaite-Memorial model to find out the average CPP from 1991 to 2004. Finally, the impacts of farmland loss on CPP were assessed. The results showed that the farmland decreased from 6158.9km2 in 1991 to 5598.9km2 in 1997, from 5121.4km2 in 2000 to 4387.8km2 in 2004. The CPP loss with three basic farmland loss models, which were polygon-farmland loss, point-farmland loss and line-farmland loss were 145.2, 206.7 and 1037.6 thousand tons respectively. From 1991 to 2004, the total CPP loss of all counties was 2236 thousand tons. The CPP loss in Miyun county was the biggest, while that in Mentougou district was the smallest. It indicates that the production capacity loss of farmland in urbanization process is obvious. Both farmland loss and its impacts on production capacity loss should be given enough attention in the policy making process of farmland preservation