No evidence for trade‐offs between bird diversity, yield and water table depth on oil palm smallholdings: Implications for tropical peatland landscape restoration. Issue 5 (14th March 2022)

• Record Type: Journal Article
• Authors: Warren‐Thomas, Eleanor; Agus, Fahmuddin; Akbar, Panji Gusti; Crowson, Merry; Hamer, Keith C.; Hariyadi, Bambang; Hodgson, Jenny A.; Kartika, Winda D.; Lopes, Mailys; Lucey, Jennifer M.; Mustaqim, Dedy; Pettorelli, Nathalie; Saad, Asmadi; Sari, Widia; Sukma, Gita; Stringer, Lindsay C.; Ward, Caroline; Hill, Jane K.
• Is Part Of: Journal of applied ecology. Volume 59:Issue 5(2022)
• Page Start: 1231
• Page End: 1247
• Publication Date: 2022-03-14
• Subjects: birds -- canal blocking -- deforestation -- Indonesia -- Jambi -- peat swamp forest -- peatlands -- Sumatra; Agriculture -- Periodicals; Biology, Economic -- Periodicals; Agricultural ecology -- Periodicals; Applied ecology -- Periodicals; 577
• DOI: 10.1111/1365-2664.14135
• Languages: English
• ISSNs: 0021-8901

Abstract

Abstract: Tropical peat swamp forests retain large carbon stocks and support unique biodiversity, but clearance and drainage for agriculture have resulted in fires, carbon emissions and biodiversity losses. Initiatives to re‐wet cultivated peatlands may benefit biodiversity if this protects remaining forests from fire and agricultural encroachment, but there are concerns that re‐wetting could reduce yields and damage livelihoods, as relationships between drainage, on‐farm biodiversity, and crop yields have not been studied. We examined oil palm fruit yields and bird diversity on 41 smallholder farms in Jambi (Sumatra, Indonesia), which varied in drainage intensity (12‐month mean water table per plot from August 2018 to August 2019: −52 to −3 cm below‐ground). We also compared farm bird diversity with a neighbouring area of protected peat swamp forest (11, 000 ha, 21 plots; mean water table per plot −3 to +15 cm). Bird species richness (3–18 species per plot), species composition and oil palm yields (4.5–19.2 t fresh fruit bunch ha −1 year −1 ) varied among farms, but were not detectably affected by water table depth, although ground‐level vegetation was more complex on wetter farms. Bird richness in oil palm (mean = 10.3 species per plot) was <50% of that in forest (26 species per plot), and only 3 of 35 conservation‐priority species found in forest were recorded in oil palm. Synthesis and applications . Tropical peatlands in Indonesia have been drained to allow farmer access and improve farm yields, but we found no trade‐offs between drainage depth, yields and bird diversity on smallholder oil palm farms in our study landscape within the studied range of drainage depths. Current restoration initiatives to re‐wet peat may benefit farmers by reducing fire risk, without affecting yields. Wetter farms had increased understorey vegetation complexity, but this did not affect bird diversity, so we find no evidence that re‐wetting improves on‐farm biodiversity. However, on‐farm fire reduction efforts in cultivated peatlands, including re‐wetting, will be vital for reducing the risk of fires escaping into nearby forests, which contain unique and diverse bird species assemblages. Protection of remaining peatland forests from fire and clearance is key for biodiversity conservation, and for providing a source of seed dispersers and genetic material for future forest and landscape restoration efforts. Restoration of more biodiversity‐friendly land covers will improve landscape permeability and help conserve species and the ecosystem services they deliver. Abstract : Tropical peatlands in Indonesia have been drained to allow farmer access and improve farm yields, but we found no trade‐offs between drainage depth, yields and bird diversity on smallholder oil palm farms in our study landscape within the studied range of drainage depths. Current restoration initiatives to re‐wet peat may benefit farmers by reducing fire risk, without affecting yields. Wetter farms had increased understorey vegetation complexity, but this did not affect bird diversity, so we find no evidence that re‐wetting improves on‐farm biodiversity. However, on‐farm fire reduction efforts in cultivated peatlands, including re‐wetting, will be vital for reducing the risk of fires escaping into nearby forests, which contain unique and diverse bird species assemblages. Protection of remaining peatland forests from fire and clearance is key for biodiversity conservation, and for providing a source of seed dispersers and genetic material for future forest and landscape restoration efforts. Restoration of more biodiversity‐friendly land covers will improve landscape permeability and help conserve species and the ecosystem services they deliver. Abstrak: Hutan rawa gambut tropis menyimpan cadangan karbon yang besar dan mendukung keanekaragaman hayati yang unik, namun pembukaan dan pengeringannya untuk pertanian telah mengakibatkan kebakaran, emisi karbon dan hilangnya keanekaragaman hayati. Inisiatif untuk membasahi kembali lahan gambut yang dibudidayakan dapat menguntungkan keanekaragaman hayati jika ini melindungi hutan yang tersisa dari kebakaran dan perluasan pertanian, tetapi ada kekhawatiran bahwa pembasahan kembali dapat mengurangi hasil dan merusak mata pencaharian, karena hubungan antara drainase, keanekaragaman hayati di lahan pertanian, dan hasil panen belum dipelajari. Kami mengevaluasi hasil buah kelapa sawit dan keanekaragaman burung di 41 perkebunan rakyat di Jambi (Sumatera, Indonesia), yang bervariasi dalam intensitas drainase (muka air tanah rata‐rata 12 bulan per plot dari Agustus 2018 hingga Agustus 2019: ‐52 hingga ‐3 cm di bawah permukaan tanah). Kami juga membandingkan keanekaragaman unggas peternakan sekitar kawasan hutan lindung di sekitarnya (11.000 ha, 21 plot; rata‐rata muka air tanah per petak ‐3 sampai +15 cm). Kekayaan spesies burung (3‐18 spesies per plot), komposisi spesies, dan hasil kelapa sawit (4, 5‐19, 2 t tandan buah segar ha‐1 thn‐1) bervariasi antar kebun, tetapi tidak terpengaruh oleh kedalaman muka air tanah, meskipun vegetasi lebih kompleks pada lahan yang lebih basah. Kekayaan jenis burung di kebun kelapa sawit (rata‐rata = 10, 3 spesies per plot) adalah <50% dibandingkan di hutan (26 spesies per plot), dan hanya tiga dari 35 spesies prioritas konservasi yang ditemukan di hutan, tercatat di kebun kelapa sawit, menegaskan pentingnya mempertahankan hutan alam. Sintesis & aplikasi . Lahan gambut telah dikeringkan untuk meningkatkan hasil panen dan akses petani, tetapi kami tidak menemukan tarik‐ulur antara drainase, hasil kelapa sawit petani kecil, atau keanekaragaman burung di lanskap studi kami. Inisiatif pembasahan gambut belakangan ini dapat menguntungkan petani dengan mengurangi risiko kebakaran, tanpa mempengaruhi hasil panen. Kebun yang lebih basah telah meningkatkan kompleksitas vegetasi tumbuhan herba bawah pohon, tetapi ini tidak mempengaruhi keanekaragaman burung, jadi kami tidak menemukan bukti bahwa pembasahan ulang meningkatkan keanekaragaman hayati. Namun, upaya pengurangan kebakaran di lahan pertanian di lahan gambut yang dibudidayakan, termasuk pembasahan kembali, akan sangat penting untuk mengurangi risiko kebakaran yang dapat meluas ke hutan terdekat. Perlindungan hutan lahan gambut yang tersisa dari kebakaran dan penebangan adalah kunci untuk konservasi keanekaragaman hayati, dan untuk menyediakan sumber penyebar benih dan materi genetik untuk upaya restorasi hutan dan lanskap di masa depan. Restorasi tutupan lahan yang lebih ramah terhadap keanekaragaman hayati akan meningkatkan permeabilitas lanskap [terhadap burung] dan membantu melestarikan spesies dan jasa ekosistem yang mereka berikan.