2000-2018年京津冀地区植被净初级生产力时空演变及其驱动因素

基于MODIS-NDVI(Moderate-Resolution Imaging Spectroradiometer, Normalized Difference Vegetation Index)、气象站点及植被类型数据, 采用改进的CASA(Carnegie-Ames-Stanford Approach) 模型估算了2000-2018年京津冀地区NPP (Net Primary Productivity), 并采用趋势分析、相关分析等方法对该地区NPP时空分布特征及其影响因素进行了分析。结果表明: 1)时间上, 2000-2018年京津冀地区NPP整体呈增加趋势(slope=0.6535 gC·(m2·a)-1), 其中草地增速最快(slope=1.5123 gC·(m2·a)-1); 2)空间上, 2000-2018年年均NPP为349.96 gC·(m2·a)-1, 高值区主要集中在燕山山脉及太行山脉等地, 低值区主要集中在西北部高原以及东部沿海地区。西北高原及山地地区植被恢复显著, 中部及沿海区域NPP退化严重; 3)地形上, NPP随海拔升高呈“增加-减少-增加”的变化趋势, 随地形起伏度整体呈增加趋势, 不同植被NPP随地形的变化大致相同; 4)就相关性来看, NPP与气温整体呈负相关关系(r=-0.03), 与降水整体呈正相关关系(r=0.36), 降水对NPP影响更大; 5)就不同地形的NPP变化来看, 中海拔地区、丘陵及山地地区绿化趋势显著, 耕地、草地和林地恢复显著, NPP显著增加; 低海拔、低起伏度处, 受耕地NPP显著减少影响, 植被退化严重。

Spatio-temporal evolution of vegetation net primary productivity and its driving factors in Beijing-Tianjin-Hebei region from 2000 to 2018

Based on Moderate-Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index(MODISNDVI),meteorological stations and vegetation type data,the Net Primary Productivity(NPP)of Beijing-Tianjin-Hebei region from 2000 to 2018 was estimated by using an improved Carnegie-Ames-Stanford Approach(CASA)model.The temporal and spatial distribution characteristics of NPP and its driving factors were analyzed by regression analysis and correlation analysis.Results showed that:1)From the view of temporal variation,the NPP in Beijing-Tianjin-Hebei region showed an increasing trend from 2000 to 2018(slope=0.6535 gC·(m²·a)^-1),and grassland with the fastest growth rate(slope=1.5123 gC·(m²·a)^-1).2)In terms of spatial distribution,the average NPP from 2000 to 2018 was 349.96 gC·(m²·a)^-1.High NPP values were mainly located in the Yan Mountains and the Taihang Mountain,while the low-value areas were mainly concentrated in the northwest plateau and the coastal areas in the east.The vegetation restoration in the northwest plateau and mountainous area was remarkable,and the NPP in the central and coastal areas was seriously degraded.3)Topographically,the NPP showed an"increase-decrease-increase"trend with altitude and an increasing trend with topographic relief.The NPP of different vegetation types had a similar change trend with the terrain.4)The correlation analysis showed that the NPP had a negative correlation with temperature(r=-0.03),and a positive correlation with precipitation(r=0.36).The NPP was mainly affected by precipitation.5)In terms of NPP changes over different terrains,there was a significant recovery of cultivated land,grassland and woodland at mid-altitude and hilly,mountainous areas.At low elevation and low fluctuation,affected by the significant reduction in NPP of cultivated land,vegetation degraded significantly.