Recently, the research team of associate professor Zhenzhong Zeng ( School of Environmental Science and Engineering, SUSTech) has made important progress in the study of the biophysical feedback mechanism of tropical mountain deforestation in the field of global change. The research is published online in Nature Geoscience (IF=13.566).

The rapid growth of the global population has intensified human demand for food. The World Resource Institute report pointed out that human demand for food in 2050 will be 1.5 times the demand in 2010 (Searchinger et al., 2019). To meet the growing demand for food, humans are cutting down tropical lowland forests for farmland expansion. A large number of studies have analyzed the impact of the land transformation, from tropical lowland forest into agricultural land, on the climate. Recent studies have shown that a large number of tropical mountain forests are also experiencing damage caused by farmland expansion (Zeng et al., 2018). Affected by topography, the biophysical feedback caused by mountain forest loss differs significantly from that of lowland forest loss. However, there are currently few reports on the interaction between mountain deforestation and climate change. In his research, Zhenzhong and his team investigate how elevation regulates the biophysical climate impacts of deforestation over tropical mountainous areas by integrating satellite-observed forest cover changes into a high-resolution land-atmosphere coupled model.

Mountain deforestation and farmland expansion（Zeng et al., 2018）

The research results show that recent forest conversion increases regional warming rate by 0.025 ±0.003 ℃ in the Southeast Asian Massif, 0.010±0.007℃ in the Barisan Mountains, 0.047±0.008℃ in the Albertine Rift Mountains, and 0.042±0.010℃ in the Serra da Espinhaco. Locally where forests are almost entirely converted, the deforestation-driven local temperature anomaly is as large as 2℃.

The effect of deforestation in tropical mountains on surface temperature in different regions

The biophysical net warming from mountain deforestation depends on elevation, through the intertwined and opposing effects of cooling caused by increased-albedo and warming caused by decreased-evapotranspiration. As elevation increases, the effect of albedo becomes greater and the deforestation-induced warming effect weakens, analogous to previously highlighted decreases of deforestation warming as a result of increasing latitude. Since most new cropland areas are encroaching land at low to moderate elevations, deforestation results in higher warming from suppressed evapotranspiration.

Analysis of the Mechanism of net warming from mountain deforestation

This research has several implications for regional environmental risk evaluation. Mountains are hotspots of biodiversity, inhabiting a large number of species. The continued mountain deforestation and the combined environmental changes such as warming will increase the extinction risk of these species. The higher temperature may also increase the risk of extreme heat that threatens human health. In addition, higher temperatures potentially increase the risk of longer fire seasons and reduce crop yields. Therefore, the impacts of this additional warming on crop yields, land degradation, and biodiversity of nearby intact ecosystems need to be accounted for in future assessments.

SUSTech is the first correspondent unit of the paper, and Zhenzhong Zeng is the first author and the only corresponding author. The project was supported by Lamsam–Thailand Sustain Development, SUSTech, and the Chinese Academy of Sciences. In addition to Prof. Zeng, researchers involved in the project included: Dashan Wang, Jie Wu, Yu Feng and Chunmiao Zheng, of SUSTech, Timothy D. Searchinger, Maofeng Liu, Ming Pan, Liqing Peng, Peirong Lin, Drew Gower and Eric F. Wood, of Princeton University, Long Yang of Nanjing University, Alan D. Ziegler of Mae Jo University, Philippe Ciais of Laboratoire des Sciences du Climat et de l’Environnement, Zong-Liang Yang of University of Texas at Austin, Deliang Chen of University of Gothenburg, Anping Chen of Colorado State University, Laurent Z. X. Li of Sorbonne Université, Shilong Piao and Xu Lian of Peking University, David Taylor of National University of Singapore, Xitian Cai of Lawrence Berkeley National Laboratory, Kaiyu Guan of University of Illinois at Urbana Champaign, Tao Wang of Chinese Academy of Sciences, Lang Wang of The Chinese University of Hong Kong, Su-Jong Jeong of Seoul National University, Zhongwang Wei of University of Tokyo, Justin Sheffield of University of Southampton, and Kelly Caylor of University of California – Santa Barbara.

Paper link: https://www.nature.com/articles/s41561-020-00666-0.

Reference

Zeng, Z. et al. Highland cropland expansion and forest loss in Southeast Asia in the twenty-first century. Nat. Geosci. 11, 556–562 (2018).

Searchinger, T. et al. Creating a sustainable food future: Final report. World Resource Institute. Washington D.C. USA (accessed: https://wrr-food.wri.org/; 2019).