陕南地区植被净第一性生产力时空动态演变

植被净第一性生产力(NPP)是生态系统服务功能的物质基础,也是生态安全、生态风险评价的重要指标。利用2000—2010年SPORT—NDVI数据、气象数据及土地利用数据,选取改进后的CASA模型,模拟了陕南地区植被净第一性生产力时间变化规律及空间分布特征。结果表明,2000—2010年,研究区各种土地利用类型的年均NPP均呈曲折上升趋势,各类土地利用类型NPP均值排列顺序为:林地灌丛草地耕地其它类型。年内变化表现为各个土地利用类型的NPP在每年的2月开始增长,同年7月达到峰值,11月开始明显减少,在次年的1月达到最小值。汉中市的西部、商洛市的东部和西部地区年均NPP增长比较明显,汉中市的中部以及安康市中部大部分地区年均NPP的增长量保持平稳,汉中市城固县与西乡县的交界处年均NPP值的减少比较明显,其它地区的年均NPP变化不明显。年内各月空间NPP的变化趋势与年际变化有一定的差别。

Spatiotemporal Dynamics of Net Primary Productivity in Southern Shaanxi Province

Net primary productivity(NPP) is a material basis of ecosystem services. NPP plays a key role in the eco-security assessment and ecological risk assessment. The data of SPORT-NDVI, meteorology and landuse from 2000 to 2010 were used to estimate the temporal variation and spatial distribution of the NPP in Southern Shaanxi Province with improved CASA model. Results indicated that the annual average NPP of various landuse types all showed an upward trend from 2000 to 2010. The land-use types, in order of decreasing NPP, were forestland, shrub land, grassland, cultivated land and other types. During the years, the NPP of various landuse types increased in February and reached a peak in July. The NPP significantly declined in November and the minimum value appeared in following January. For the spatial distribution, the annual average NPP increased significantly in western Hanzhong City and the eastern and western regions of Shangluo City, increased steadily in the center of Hanzhong City and the most parts of central Ankang City, declined obviously at the juncture of Chenggu and Xixiang Counties, but did not change obviously in other regions of Southern Shaanxi Province. The NPP differences between monthly and annual change trends were apparent.