Wang Zhao, Li Deng Ke
Shaanxi Remote Sensing Information Center for Agriculture, Xi'an 710014, China.
Ying Yong Sheng Tai Xue Bao. 2018 Jun;29(6):1876-1884. doi: 10.13287/j.1001-9332.201806.029.
Using MOD17A3 NPP time series data, surface cover type data, weather data, MOD16 evapotranspiration products and terrain data, the temporal and spatial variability of vegetation net primary productivity (NPP) in Shaanxi Province from 2000 to 2015 was analyzed, and its response to each influencing factor were discussed. The results showed that the NPP of Shaanxi had a significant upward trend in the past 16 years with a slope of 5.02 g C·m·a. The annual average of NPP was 344 g C·m·a with a range from 247 to 390 g C·m·a. The NPP at 61.2% area of Shaanxi Province showed a significant increasing trend, which were mainly distributed at northern part of Shaanxi, Weibei area and western part of Qinba Mountain. There was a decrease trend of NPP for the area around Xi'an and Baoji City, accounting for only 2.5% of the whole province. During the study period, the variation of annual mean temperature and annual precipitation in Shaanxi showed no significance. The temperature showed a increase trend and the precipitation showed a decrease trend, implying a drier and warmer climate trend in Shaanxi Province. The areas with significant correlation between NPP and precipitation and temperature accounted for 9.4% and 1.5% of the total area of the province. The frequent intervention of human activities reduced the impact of climate on the changes of NPP, so human activity had gradually become the dominant factor. NPP in northern Shaanxi and Guanzhong areas was significantly correlated with evapotranspiration. The increases of NPP in these areas would have great influence on the water and heat balance. The average NPP at different land cover was farmland > forestland > grassland > garden, increasing rate of NPP at different land cover was garden > grassland > forestland > farmland, and proportional changes of NPP was grassland > garden > forestland > farmland. The increasing percentage of NPP at three gradient ranges were 14.6% (0°-5°), 25.7% (5°-25°) and 35.9% (>25°), respectively.
利用MOD17A3净初级生产力（NPP）时间序列数据、地表覆盖类型数据、气象数据、MOD16蒸散产品以及地形数据，分析了2000—2015年陕西省植被净初级生产力（NPP）的时空变化特征，并探讨了其对各影响因子的响应。结果表明，陕西省NPP在过去16年呈显著上升趋势，斜率为5.02 g C·m⁻²·a⁻¹。NPP年均值为344 g C·m⁻²·a⁻¹，范围在247390 g C·m⁻²·a⁻¹之间。陕西省61.2%区域的NPP呈显著增加趋势，主要分布在陕北地区、渭北地区和秦巴山区西部。西安市和宝鸡市周边区域NPP呈下降趋势，仅占全省面积的2.5%。研究期内，陕西省年平均气温和年降水量变化均不显著。气温呈上升趋势，降水呈下降趋势，意味着陕西省气候有暖干化趋势。NPP与降水和气温显著相关的区域分别占全省总面积的9.4%和1.5%。人类活动的频繁干预降低了气候对NPP变化的影响，人类活动逐渐成为主导因素。陕北和关中地区的NPP与蒸散显著相关。这些地区NPP的增加对水热平衡有很大影响。不同土地覆盖类型的平均NPP表现为农田>林地>草地>园地，不同土地覆盖类型的NPP增加速率表现为园地>草地>林地>农田，NPP的比例变化表现为草地>园地>林地>农田。三个坡度范围的NPP增加百分比分别为14.6%（0°5°）、25.7%（5°~25°）和35.9%（>25°）。
