Trends in vegetation productivity related to climate change in China’s Pearl River Delta

RESEARCH ARTICLE Trends in vegetation productivity related to climate change in China’s Pearl River Delta Sawaid Abbas1☯, Janet E. Nichol2☯, Man Sing WongID1,3* 1 Department of Land Surveying and Geo-informatics, The Hong Kong Polytechnic University, Hong Kong SAR, China, 2 Department of Geography, School of Global Studies, University of Sussex, Falmer Brighton, United Kingdom, 3 Research Institute for Sustainable Urban Development, The Hong Kong Polytechnic University, Hong Kong SAR, China ☯ These authors contributed equally to this work. * Lswong@polyu.edu.hk Abstract Climate change will be a powerful stressor on ecosystems and biodiversity in the second half of the 21st century. In this study, we used the satellite-derived Normalized Difference Vegetation Index (NDVI) to examine a 34-year trend along with the response of vegetation to climate indicators surrounding the world’s largest megacity: the Pearl River Delta (PRD) of China. An overall increasing trend is observed in vegetation productivity metrics over the study period 1982 to 2015. Increase in winter productivity in both natural ecosystems and croplands is more related to increasing temperatures (r = 0.5–0.78), than to changes in rain- fall. For growing season productivity, negative correlations with temperature were observed in cropland regions, and some forests in the northern part of PRD region, suggesting high- temperature stress on crop production and forest vegetation. However, increased winter and spring temperatures provide higher opportunities for cropping in winter. During the

decade 1995–2004, vegetation productivity metrics showed a reversal in the upward trend. The geographical and biological complexity of the region under significant climatic and development impacts suggests causative factors would be synergistic. These include our observed decrease in sunshine hours, increasing cloud cover associated with atmospheric aerosols from industrial and urban development, direct pollution effects on plant growth, and exceedance of high temperature growth thresholds. Introduction The Intergovernmental Panel on Climate Change (IPCC)’s Fifth Assessment Report (AR5), expresses high confidence that climate change will be a powerful stressor on both natural and cultivated ecosystems in the second half of the 21st century [1], especially under high-warming scenarios. The IPCC also cites impacts on global food production such as a potential 10–22% reduction in the Chinese rice yield [2], and decline in tropical plants which are already nearing their upper thermal limits [3]. In most cities of the developing world, the surrounding hinter- lands are intensively cultivated to supply urban markets, therefore more significant impacts of climate change on food production would be expected. PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0245467 February 24, 2021 1 / 20 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Abbas S, Nichol JE, Wong MS (2021) Trends in vegetation productivity related to climate change in China’s Pearl River Delta. PLoS ONE 16(2): e0245467. https://doi.org/10.1371/journal. pone.0245467

Editor: Simone Lolli, Italian National Research Council (CNR), ITALY Received: April 9, 2020 Accepted: December 31, 2020 Published: February 24, 2021 Copyright: © 2021 Abbas et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All the outputs and relevant data are within the manuscript and its Supporting Information files. All the date used in this study are available from following sources. GIMMS NDVI3g.v1 is available from http://poles. tpdc.ac.cn/en/data/9775f2b4-7370-4e5e-a537- 3482c9a83d88/ MODIS LCLU product (MCD12Q1) is available from LP DAAC, https://lpdaac.usgs.gov CHIRPS is available from https://data.chc.ucsb. edu/products/CHIRPS-2.0/ APHRODITE is available from http://aphrodite.st.hirosaki-u.ac.jp/download/ GLC30 is available from http://www. globallandcover.com/GLC30Download/ Bioclimatic