Selva Dhandapani
Catherine M. Yule
Julia Drewer- 1Soil Biogeochemistry and Terrestrial Ecology Research Programme, Agri-Food Biosciences Institute (AFBI), Belfast, United Kingdom
- 2School of Science, Technology and Engineering, University of the Sunshine Coast, Maroochydore, QLD, Australia
- 3Biosphere Atmosphere Exchange and Effects (BAEE) Group, UK Centre for Ecology and Hydrology, Penicuik, United Kingdom
Editorial on the Research Topic
Biogeochemical and biodiversity impacts of oil palm land-use in Southeast Asia
Rationale
Southeast Asia is home to one of the oldest and most consistent rainforests in the world, with high endemic biodiversity and carbon storage, and the largest cover of carbon-rich tropical peat swamp forests (Yule, 2010; Xu et al., 2018). However, these tropical forests are becoming increasingly disturbed by anthropogenic land-use changes, particularly the expansion of oil palm agriculture (Miettinen et al., 2016; Dhandapani et al., 2023). Oil palm currently stands as the fastest expanding equatorial crop and the most traded vegetable oil in the world (USDA, 2023), and 85% of the world's oil palm production comes from Malaysia and Indonesia (USDA, 2023). The rapid expansion of oil palm plantations in the last few decades has directly coincided with rapid deforestation (Hansen et al., 2013; Shevade and Loboda, 2019). Between 1990 and 2010, forest cover in the region reduced from 268 to 236 million ha (Stibig et al., 2014), and is predicted to shrink a further 5.2 million ha by 2050 (Estoque et al., 2019), which has been disastrous for global biodiversity and climate (Sodhi et al., 2004; Dhandapani, 2015; Cooper et al., 2020).
A greater understanding of the environmental impacts of forest conversion and different oil palm management practices would support improved management of oil palm plantations that already cover large areas of Southeast Asia. It is a crucial time to understand their impacts in detail, considering the further expansion of oil palm in its native Africa, and other tropical regions such as South America and Papua New Guinea (Sayer et al., 2012; Pashkevich et al., 2024). For example, there are some indications that oil palm intercropping ameliorates the impact of oil palm plantations on both biodiversity and biogeochemical cycling in Southeast Asia (Dhandapani et al., 2020, 2022), however, research has been lacking on the environmental impacts of different oil palm cropping systems and management practices. This Research Topic therefore brings together a diverse and wide range of new research on subjects from soil microbial communities, soil physics and biogeochemistry, greenhouse gas emissions, terrestrial and semiaquatic invertebrate biodiversity in oil palm plantations on peat and mineral soils. There is a common thematic focus on oil palm management practices to mitigate GHG emissions and biodiversity loss, such as soil compaction to reduce impact of fire disturbance (Samuel and Evers), management of diverse habitat features (Manning et al.) such as understorey vegetation (Reiss-Woolever et al.; Drewer et al.) and riparian buffers (Drewer et al.; Harianja et al.).
Novel findings
An important disturbance in Southeast Asian tropical peatlands is fire which follows draining and clearing for oil palm cropping. Fires dramatically increase greenhouse gas (GHG) emissions and reduce air quality even past incidence of the fire event (Dhandapani and Evers, 2020). There is a lack of evidence based mitigation strategies for controlling and reducing carbon (C) losses from fire. Samuel and Evers suggest that in the absence of groundwater influence, compaction could be one of the solutions in mitigating carbon loss from fire in their controlled study, however they acknowledge the complexity in the field and the vital role groundwater level plays in tropical peatland management. Nevertheless, it is a first step in understanding the influence of compaction on GHG emissions and potential for mitigation of C emissions from fire related disturbances. The degradation in soil health of already established oil palm plantations (Guillaume et al., 2016; Woittiez et al., 2018) will result in farmers moving to productive soil necessitating further forest encroachments and deforestation (Pramudya et al., 2018).
Soil microbes play an important role in soil functions, particularly in nutrient cycling and decomposition of organic matter, hence in maintaining soil health, however soil microbial communities in oil palm plantations are understudied (Drewer et al., 2021). Azizan et al. found significant differences between microbial communities on peat in oil palm plantations and forest with respect to notable changes in specific bacterial groups in the deeper layers which are likely to influence carbon sequestration and nitrogen cycling.
The preparation of oil palm planting sites negatively impacts soil and particularly peat properties with increased heterotrophic carbon dioxide (CO2) emissions, resulting in increased carbon loss and accelerating climate change (Tonks et al., 2017). Manning et al. showed significant spatial variation and the difference between autotrophic and heterotrophic regions, adding new findings to previous research on this subject (Dhandapani et al., 2022). Manning et al. further presented a more accurate way of estimating plantation level CO2 emissions from soil, by performing area-weighted upscaling and accounting for variations in soil CO2 emissions from different spatial features. Accurate estimations of the impacts are critical to develop effective solutions.
Reiss-Woolever et al. and Harianja et al. showed the importance of enhancing habitat complexity to mitigate biodiversity loss with no significant negative impact on GHG emissions (Drewer et al.). The management features that benefit biodiversity also generally benefit biogeochemistry of peat and biogeochemical cycles, similar to what is observed in intercropping systems (Dhandapani et al., 2019). Considering the large cover of oil palm plantations in Southeast Asia, and importance of oil palm in serving global food and energy needs as well as improving local economies, there is a need to investigate sustainable management practices for biodiversity conservation, in addition to protecting forests. Reiss-Woolever et al. emphasize the importance of limiting vegetation clearance in oil palm plantations to maintain habitat complexity and conserve biodiversity. Despite finding 55 species of Lepidoptera in this study, no forest specialist species were found in oil palm plantations with or without intensive management of ground vegetation, emphasizing the relative importance of forest habitats for biodiversity conservation. Further, no pest species were found in less intensive understorey management, indicating minimal risks for farm productivity. Drewer et al. add to this by showing no difference in GHG emissions with increased ground vegetation. So, the current studies show no negative impact from less intensive management of ground vegetation, but many proven benefits for biodiversity (Hood et al., 2020; Reiss-Woolever et al.) and biogeochemistry (Ashton-Butt et al., 2018).
Conclusions
To reduce the adverse impacts of the continued expansion of oil palm plantations in Southeast Asia, and more recently into Central and South America, and West Africa, it is crucial to draw on the lessons learned from over a century of oil palm cultivation in Malaysia and Indonesia. By implementing sustainable practices such as limiting forest loss and less intensive management, biodiversity loss and greenhouse gas emissions can be mitigated.
Author contributions
SD: Conceptualization, Writing – original draft, Writing – review & editing. CY: Writing – original draft, Writing – review & editing. JD: Writing – original draft, Writing – review & editing.
Funding
The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher's note
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Keywords: tropical agro-ecology, tropical peatlands, greenhouse gas emissions, peat fire, riparian buffers, understorey vegetation, sustainable agriculture, land-use change
Citation: Dhandapani S, Yule CM and Drewer J (2024) Editorial: Biogeochemical and biodiversity impacts of oil palm land-use in Southeast Asia. Front. For. Glob. Change 7:1441266. doi: 10.3389/ffgc.2024.1441266
Received: 30 May 2024; Accepted: 28 June 2024;
Published: 09 July 2024.
Edited and reviewed by: Geertje M. F. Van Der Heijden, University of Nottingham, United Kingdom
Copyright © 2024 Dhandapani, Yule and Drewer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Selva Dhandapani, selvakumar.dhadnapani@afbini.gov.uk; sccalva@gmail.com