Contributions of vegetation restoration and climate change to spatiotemporal variation in the energy budget in the loess plateau of china

Abstract

Quantifying the impacts of vegetation restoration (VR) on energy exchange is essential for exploring climate-vegetation interactions. Due to the complexity of land–atmosphere energy exchange and limited observation networks, the influence of VR on the energy balance remains unclear. To improve the understanding of the energy budget change associated with VR in the Loess Plateau (LP), we performed a series of sensitivity simulation experiments using the Community Land Model within the Community Earth System Model, and the spatiotemporal responses of energy exchange to VR and the roles of VR in the variations in energy budget under climate change were investigated. The results showed that the land cover changes from 2000 to 2015 exerted a positive effect on net radiation (NR) and sensible heat (SH), and evident increases in annual mean NR and SH were found in the southeastern LP where larger-scale cropland was converted to grassland or forestland, with increasing magnitudes exceeding 2 W/m2. Latent heat (LH) increased only during May–July, particularly on the southern edge of LP. The increasing magnitudes of NR and LH under Representative Concentration Pathway (RCP)8.5 were larger than those under RCP4.5, with the greatest differences being approximately 4 W/m2 and 5 W/m2 during 2081–2100 for NR and LH, respectively. SH remained nearly stable under RCP4.5 and showed a weak decrease under RCP8.5. Under the same RCP, only slight differences in the energy budget components were detected between the land cover condition in 2015 and 2000, with the largest difference of 0.8 W/m2 in SH during 2021–2040. These results suggested that although both VR and climate warming exerted positive effects on NR, the impact of climate change was larger than that of VR in the LP, and a shift in the local surface energy budget toward LH would occur with climate warming.

Keywords

• Change detection
• Energy exchange
• Land cover change
• Loess Plateau
• Reforestation