Warming Effect of AsianTropical Forest Loss and Its Influence Mechanism

doi:10.3969/j.issn.1000-6362.2020.04.001

Abstract

Abstract: Tropical forest area has been decreasing in recent decades due to defores tation and wildfire. The rate of forest loss is rising. The loss of tropical forest cover modifies the surface heat, moisture and mass exchange, thus influences the tropical climate. In order to understand the impact of tropical forest loss on tropical climate, a window search method was applied by using remote sensing forest change products to identify forest cover loss from 2000 to 2017 in Asia tropics. The difference of surface temperature (LST), net surface shortwave radiation (SW) and latent heat flux (LE) between adjacent forest reduced grids and unchanged forest grids in the same window was calculated , thus evaluating the biophysical effect of forest loss on surface temperature and its influence mechanism in two different forest types, i.e. tropical rainforest and tropical monsoon forest. The results showed that:(1) the cumulative reduction of Asian tropical rainforest between 2000 and 2017 has led to warming impact (1.7±0.7℃) on daily surface temperature. Downward shortwave radiation has decreased 7.2±0.9Wm-2, and the latent heat flux has increased 8.9±4.4Wm-2 due to rainforest loss.(2) The loss of tropical monsoon forest has led to stronger warming impact (2.1±0.9℃) than tropical rainforest. Downward shortwave radiation has decreased 7.1±1.0Wm-2 due to monsoon forest loss. Latent heat flux has decreased 3.9±9.2Wm-2due to monsoon forest loss, which is opposite to the change due to rainforest loss. (3)The loss of tropical rainforest has a limited effect on the seasonal distribution of surface temperature, downward shortwave radiation and latent heat flux. However, the loss of tropical monsoon forest has caused contrasting seasonal changes in surface temperature, downward shortwave radiation, and latent heat flux. This is mainly due to contrasting seasonal precipitation in monsoon forest which determines the surface water supply for evapotranspiration. (4)The net change of downward shortwave radiation and latent heat flux (△SW-△LE) can explainthe surface temperature change of monsoon forest to some extent, but not that of tropical rainforest.Therefore, in the context of climate change, it needsto take measures to prevent forest loss in tropical areas and mitigate warming impact due to landcover change.

Key words: Forest loss, Warming effect, Energy change, Rainforest, Monsoon forest

CLC Number:

XUE Ying，XU Xi-yan,HU Zheng-hua，JIA Gen-suo，ZHANG Xiao-yan，MA Wei. Warming Effect of AsianTropical Forest Loss and Its Influence Mechanism[J]. Chinese Journal of Agrometeorology, 2020, 41(04): 191-200.

References

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