1985—2010年太湖流域粮食产能隐性增减评估研究

耕地占补制度旨在缓解耕地的增减失衡，但事实导致粮食产能的隐性增减。构建耕地数量-质量关联的粮食产能隐性增减评估系数F（耕地综合隐性增减折算系数）和TR（耕地隐性增减相对显性增减的折算面积），揭示太湖流域25 a 来粮食产能隐性增减特征及机制。1985—2000 年流域耕地增减失衡并存在粮食产能隐性流失，耕地年均递减率为0.33%，而耕地新增极少，F系数、TR系数比例分别为-1.044、7.42%；2000—2010 年耕地增减失衡加剧，但粮食产能隐性流失减缓，耕地年均流失率增至1.50%，但耕地新增显著，F 系数、TR 系数比例分别降至-0.515、2.07%。产能隐性增减特征归于耕地增减区的土壤质量等级差异，而这差异又与流域发展及耕地政策影响下耕地增减转换过程的响应特征有关：2000 年前流失耕地比新增耕地的土壤肥力略优，而2000 年后新增耕地土壤肥力显著提升，城市及开发区周边的建设用地扩展是肥力优良耕地流失的主因，而耕地占补制度提升了耕地新增数量和质量。贯彻耕地占补制度并将数量-质量挂钩，优化耕地增减质量结构以减少耕地隐性流失是提高未来太湖流域粮食生产能力的根本出路。

Measuring the Invisible Increase and Decrease of the Grain Productivity in Taihu Lake Watershed during 1985-2010

As we known, the policy of cultivated land occupation and supplement aims to mitigate the imbalance between cultivated land increase and decrease. But in fact, it led to invisible increase and decrease of grain productivity in many places of China. By use of establishing the invisible increase and decrease evaluation coefficient F and TR of grain productivity, which connected with variation of cultivated land quantity and quality, this paper reveals the characteristics and mechanism of invisible increase and decrease of grain productivity in Taihu Lake Watershed in the past 25 years. During 1985 and 2000, an imbalance between increase and decrease of cultivated land area in Taihu Lake Watershed existed, as well as the invisible reduction of grain productivity, the annual decline rate of cultivated land area was 0.33%, but the newly supplied cultivated area was rare, and the evaluation coefficient F and TR ratio were -1.044 and 7.42% respectively. However, during 2000 and 2010, the imbalance was aggravated, but the invisible reduction was mitigated. The annual decline rate of cultivated land area increased to 1.50%, but the newly supplied cultivated land area augmented significantly and the evaluation coefficient F and TR ratio were dropped to -0.515 and 2.07% respectively. The invisible change characteristics of grain productivity attributed to the soil quality level differences of varied cultivated land regions, while the differences were related to the response characteristics of the transformation process between cultivated land increase and decrease, which was affected by basin development and cultivated land policy: before 2000 the cultivated land occupation area had higher soil fertility than the cultivated land supplement area, but after 2000 the soil fertility of cultivated land supplement area was raised significantly; the construction activities around cities and developing zones was the primary cause for the erosion of the highly fertilized cultivated land, while the cultivated land occupation and supplement policy had improved quantity and quality of newly increased cultivated land. Finally, the comparison of the method and the existing relative methods showed that the evaluation coefficient F involved in the connection between the quantity and quality of cultivated land and especially revealed the part of invisible increase and decrease of cultivated land change, but farmland-grain elasticity coefficient revealed the relationship between the quality and yield of cultivated land despite of the invisible part of grain yield capacity and the cases of graduation coefficient method is similar with this method and does not pay attention to the dynamic change of grain yield and cultivated land quality graduation. Therefore, under the background of urbanization and industrialization development, executing the cultivated land occupation and supplement policy and connecting cultivated land area quantity with its quality, optimizing the quality structure of increased and decreased farmland to reduce the invisible loss of cultivated land are the fundamental solutions to enhance the crop productivity of Taihu LakeWatershed in the future.