Simulation on the dynamics of forest area changes in Northeast China

There is plenty of forests in Northeast China which contributes a lot to the conservation of water and land resources, produces timber products, and provides habitats for a huge number of wild animals and plants. With changes of socio-economic factors as well as the geophysical conditions, there are dramatic changes on the spatial patterns of forest area. In this sense, it is of great significance to shed light on the dynamics of forest area changes to find the underlining reasons for shaping the changing patterns of forest area in Northeast China. To explore the dynamics of forest area change in Northeast China, an econometric model is developed which is composed of three equations identifying forestry production, conversion from open forest to closed forest and conversion from other land uses to closed forest so as to explore the impacts on the forest area changes from demographic, social, economic, location and geophysical factors. On this basis, we employ the Dynamics of Land System （DLS） model to simulate land-use conversions between forest area and non-forest cover and the land-use conversions within the sub-classes of forest area for the period 2000-2020 under business as usual scenario, environmental protection scenario and economic growth scenario. The simulation results show that forest area will expand continuously and there exist various kinds of changing patterns for the sub-classes of forest area, for example, closed forest will expand continuously and open forest and shrub will decrease a little bit, while area of other forest will keep intact. The research results provide meaningful decision-making information for conserving and exploiting the forest resources and makJng out the planning for forestry production Jn the Northeast China region.

Estimation of Land Production and Its Response to Cultivated Land Conversion in North China Plain

Food safety and its related influencing factors in China are the hot research topics currently,and cultivated land conversion is one of the significant factors influencing food safety in China.Taking the North China Plain as the study area,this paper examines the changes of cultivated land area using satellite images,estimates land productivity from 1985 to 2005 using the model of Estimation System for Land Productivity(ESLP),and analyzes the impact of cultivated land conversion on the land production.Compared with the grain yield data from statistical yearbooks,the results indicate that ESLP model is an effective tool for estimating land productivity.Land productivity in the North China Plain showed a slight decreasing trend from 1985 to 2005,spatially,increased from the north to the south gradu-ally,and the net changes varied in different areas.Cultivated land area recorded a marginal decrease of 8.0 × 105 ha,mainly converted to other land uses.Cultivated land conversion had more significant negative impacts on land produc-tion than land productivity did.Land production decreased by about 6.48 × 106 t caused by cultivated land conversion between 1985 and 2005,accounting for 91.9% of the total land production reduction.Although the land productivity increased in Anhui and Jiangsu provinces,it can not offset the overall adverse effects caused by cultivated land con-version.Therefore,there are significant meanings to control the cultivated land conversion and improve the land pro-ductivity for ensuring the land production in the North China Plain.

张承地区植被指数时空演变特征及其与气候因子的关系

为研究对张承地区生态环境质量改善具有重要现实意义的植被动态变化及其与气候影响因素间的关系,本研究解析张承地区2000—2014年气候因子与植被指数(NDVI)的时空演变特征,进而揭示该区域气候因子与植被指数的相关关系。结果表明:1)2000—2014年张承地区NDVI整体呈现增长趋势,年际波动较大,季节差异和空间分异特征显著。2)对于气候要素,15年间光合有效辐射与气温呈下降趋势,而年降水量呈现出增长趋势,且具有明显季节差异。3)在季节尺度上,夏季NDVI与降水量的相关性最显著,而在冬季NDVI与气温和光合有效辐射的相关性更显著;在年际尺度上,NDVI与光合有效辐射相关性较低,但却与降水量呈显著正相关,与气温呈显著负相关。4)不同植被类型的NDVI与气候因子的相关程度存在差异,但对于同一植被类型,NDVI与降水量的相关性最高。这些研究结论将为张承地区应对气候变化、改善生态环境提供重要参考信息。