Spatio-temporal variation of vegetation net primary productivity and its driving factors in the Haihe River Basin

Abstract

To reveal the spatio-temporal variation characteristics of vegetation net primary productivity (NPP) in the Haihe River Basin and the driving mechanisms of its spatio-temporal heterogeneity, we studied the spatio-temporal pattern evolution characteristics of vegetation NPP in the Haihe River Basin from 2000 to 2020 using coefficient of variation, trend analysis, and Hurst index, based on MOD17A3HGF dataset. Driving factors from natural and human aspects and their influence were also quantitatively explored for vegetation NPP variations using correlation analysis and the Geodetector model. The results were as follows: (1) The temporal variation of vegetation NPP in the Haihe River Basin presented a significant growth trend form 2000 to 2020, with a rate of 1.73 Tg C·a-1, and the annual average NPP was 326.75 g C·m-2·a-1; the average NPP of coniferous forests, broad-leaved forest, shrub, grassland and farmland were 313.59, 385.28, 353.03, 320.12, 295.22 g C·m-2·a-1. (2) In terms of spatial distribution, the high-value areas of vegetation NPP were mainly located in the northwest mountains, and the low-value areas were mainly located in the southeast plain; the overall situation of vegetation NPP was relatively stable, with an average coefficient of variation of 0.17; the future trend of NPP was anti-continuity and might decrease. (3) The correlation analysis showed that vegetation NPP was negatively correlated with temperature, and positively correlated with precipitation that was the main climate factor; NPP showed an “increase-decrease” trend with elevation and slope increasing; the conversion of farmland to grassland resulted in the largest increment of NPP at 732.22×10-3 Tg C. (4) From 2000 to 2020, the average influence value of different drivers was 0.2, and the order was precipitation > elevation > slope > humidity > temperature > sunshine duration > land use > wind speed. Overall, the results indicated that vegetation NPP in the Haihe River Basin was improving during the study period; productivity varied among different vegetation types, with the strongest being broad-leaved forest and shrubland; the dominant factors affecting the spatial distribution of vegetation NPP were precipitation, elevation and slope, and the influence of human factors was lower than that of natural factors. The results of this study provide some scientific reference and decision basis for the treatment of ecological environment such as soil erosion and vegetation degradation in the Haihe River Basin.

Keywords

• net primary productivity(npp)
• mod17a3hgf
• spatio-temporal variation
• driving factors
• the haihe river basin