BGD Biogeosciences Discussions BGD Biogeosciences Discuss. 1810-6285 Göttingen, Germany 10.5194/bg-2021-303 Effects of tropical rainforest conversion to rubber plantation on soil quality in Hainan Island, China Sun Rui https://orcid.org/0000-0002-0865-5066 1 2 Lan Guoyu https://orcid.org/0000-0003-4019-4252 1 2 Yang Chuan 1 2 Wu Zhixiang https://orcid.org/0000-0002-7344-8717 1 2 Chen Banqian 1 2 Fraedrich Klaus 3 Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China Hainan Danzhou Agro-ecosystem National Observation and Research Station, Danzhou 571737, China Max Planck Institute for Meteorology, Hamburg 20146, Germany National Natural Science Foundation of China 31770661 Earmarked Fund for China Agriculture Research System CARS-33-ZP3 08 12 2021 2021 1 44 Copyright: © 2021 Rui Sun et al. 2021 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://bg.copernicus.org/preprints/bg-2021-303/ The full text article is available as a PDF file from https://bg.copernicus.org/preprints/bg-2021-303/bg-2021-303.pdf

<p>Land-use changes can alter soil properties and thus affect soil quality. Our understanding of how forest conversion (from tropical rainforest to rubber plantations) affects soil properties and soil quality is limited. An ideal testing ground for analyzing such land-use change and its impacts is Hainan Island, the largest tropical island in China. Based on 21 soil physicochemical and biological properties, a soil quality index (SQI) employed principal component analysis to assess soil quality changes from the conversion of tropical rainforests to rubber plantations. The results showed that (i) soil available potassium, available phosphorus, microbial biomass carbon, cellulose decomposition, acid phosphatase, and urease were vital soil properties for soil quality assessment on Hainan Island. (ii) The SQI of rubber plantations decreased by 26.48 % compared to tropical rainforests, while four investigated soil properties (soil pH, total phosphorus, cellulose decomposition, and actinomyces) increased. (iii) The SQI of both the tropical rainforests and rubber plantations showed significant spatial differences, which, under tropical rainforests, was more sensitive to seasonal changes than those under rubber plantations. (iv) Structural equation modeling suggested that forest conversion directly impacted soil quality and, indirectly impacted soil qualities' spatial variation by their interaction with soil types and geographical positions. Overall, though the conversion of tropical rainforest to rubber plantation did not decrease all soil properties, the tropical rainforest with its high soil quality should be protected.</p>