Effects of Land Cover Changes on Net Primary Productivity in the Terrestrial Ecosystems of China from 2001 to 2012

Hanwei Li,Changhui Peng,Bin Yang,Juhua Ding,Qiuan Zhu,Zhenan Yang,Jiang Zhang

doi:10.3390/land9120480

Abstract

The 2001–2012 MODIS MCD12Q1 land cover data and MOD17A3 NPP data were used to calculate changes in land cover in China and annual changes in net primary productivity (NPP) during a 12-year period and to quantitatively analyze the effects of land cover change on the NPP of China’s terrestrial ecosystems. The results revealed that during the study period, no changes in land cover type occurred in 7447.31 thousand km2 of China, while the area of vegetation cover increased by 160.97 thousand km2 in the rest of the country. Forest cover increased to 20.91%, which was mainly due to the conversion of large areas of savanna (345.19 thousand km2) and cropland (178.96 thousand km2) to forest. During the 12-year study period, the annual mean NPP of China was 2.70 PgC and increased by 0.25 PgC, from 2.50 to 2.75 PgC. Of this change, 0.21 PgC occurred in areas where there was no land cover change, while 0.04 PgC occurred in areas where there was land cover change. The contributions of forest and cropland to NPP exhibited increasing trends, while the contributions of shrubland and grassland to NPP decreased. Among these land cover types, the contributions of forest and cropland to the national NPP were the greatest, accounting for 40.97% and 27.95%, respectively, of the annual total NPP. There was no significant correlation between changes in forest area and changes in total annual NPP (R2 < 0.1), while the correlation coefficient for changes in cropland area and total annual NPP was 0.48. Additionally, the area of cropland converted to other land cover types was negatively correlated with the changes in NPP, and the loss of cropland caused a reduction in the national NPP.

Highlights

Net primary production (NPP) represents the total amount of organic matter accumulated by vegetation per unit area and time and is the difference between the carbon absorbed by photosynthesis and the carbon released by autotrophic respiration [1]
0.21 PgC occurred in areas where there was no land cover change, while 0.04 PgC occurred in areas where there was land cover change
We found that during the 12-year period, the vegetation cover in China has increased, of which forest area displayed the largest increase

Summary

Introduction

Net primary production (NPP) represents the total amount of organic matter accumulated by vegetation per unit area and time and is the difference between the carbon absorbed by photosynthesis and the carbon released by autotrophic respiration [1]. Land 2020, 9, 480 of different vegetation types, there are differences in NPP per unit area [3]. Land use and land cover change (LUCC) is a popular topic in global research and is one of the important factors by which human activities can induce changes in total NPP in terrestrial ecosystems. Against the background of the increasing impact of global changes and human activities on the ecological environment, several international studies have employed terrestrial ecosystem models to investigate the effects of land use and land cover change on NPP [6]. Since the 19th century, international researchers have obtained many important results on the relationship between global or regional ecosystem NPP and climatic factors, precipitation and temperature. The driving mechanisms behind the spatiotemporal heterogeneity of NPP at the regional level remain unclear [3]

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Discussion

Conclusion