4 research outputs found
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Managing Oil Palm Plantations More Sustainably: Large-Scale Experiments Within the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme
Conversion of tropical forest to agriculture results in reduced habitat heterogeneity, and associated declines in biodiversity and ecosystem functions. Management strategies to increase biodiversity in agricultural landscapes have therefore often focused on increasing habitat complexity; however, the large-scale, long-term ecological experiments that are needed to test the effects of these strategies are rare in tropical systems. Oil palm (Elaeis guineensis Jacq.)âone of the most widespread and important tropical cropsâoffers substantial potential for developing wildlife-friendly management strategies because of its long rotation cycles and tree-like structure. Although there is awareness of the need to increase sustainability, practical options for how best to manage oil palm plantations, for benefits to both the environment and crop productivity, have received little research attention.
In this paper we introduce the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme: a long-term research collaboration between academia and industry in Sumatra, Indonesia. The BEFTA Programme aims to better understand the oil palm agroecosystem and test sustainability strategies. We hypothesise that adjustments to oil palm management could increase structural complexity, stabilize microclimate, and reduce reliance on chemical inputs, thereby helping to improve levels of biodiversity and ecosystem functions. The Programme has established four major components: (1) assessing variability within the plantation under business-as-usual conditions; (2) the BEFTA Understory Vegetation Project, which tests the effects of varying herbicide regimes; (3) the Riparian Ecosystem Restoration in Tropical Agriculture (RERTA) Project, which tests strategies for restoring riparian habitat; and (4) support for additional collaborative projects within the Programme landscape. Across all projects, we are measuring environmental conditions, biodiversity, and ecosystem functions. We also measure oil palm yield and production costs, in order to assess whether suggested sustainability strategies are feasible from an agronomic perspective.
Early results show that oil palm plantation habitat is more variable than might be expected from a monoculture crop, and that everyday vegetation management decisions have significant impacts on habitat structure. The BEFTA Programme highlights the value of large-scale collaborative projects for understanding tropical agricultural systems, and offers a highly valuable experimental set-up for improving our understanding of practices to manage oil palm more sustainably.This work was funded by The Isaac Newton Trust Cambridge, Golden Agri Resources, ICOPE (the International Conference on Oil Palm and the Environment), and the Natural Environment Research Council [grant number NE/P00458X/1]
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How do management decisions impact butterfly assemblages in smallholding oil palm plantations in Peninsular Malaysia?
1. In the worldâs leading palm oil producing countries (Indonesia and Malaysia), smallholders make up about 40 percent of total oil palm plantation area. Management in smallholdings can be highly variable, ranging from intensive monoculture to polyculture systems, especially in the earlier years of cultivation when open canopies allow a variety of understory crop types to be grown alongside oil palm. Currently, many plantations in the region are mature and due to be replanted, which is likely to have substantial impacts on the ecosystems within them, but studies investigating the impacts of alternative post-replanting management strategies in smallholder plantations are lacking.
2. We investigated the impacts of replanting and choice of crop management following replanting (growing oil palm as a monoculture or polyculture) on habitat structure and complexity, and on the abundance, richness, and composition of butterfly assemblages in smallholding oil palm plantations in Banting, Selangor, Malaysia. We also assessed the direct effects of habitat structure and complexity on butterfly assemblages. Butterflies are likely to be a valuable indicator group for monitoring impacts of management practices on biodiversity as butterfly species also show a range of sensitivities to habitat disturbance, with some being vulnerable to change, but others being common in plantations. They are also a functionally important group that pollinate wild plants, are prey for larger species, and are common in tropical systems.
3. Across 27 plantations, we recorded 1227 butterflies from 5 families, 46 genera, and 56 species. Habitat structure and complexity differed between management decisions (mature monoculture, immature monoculture, immature polyculture), although many environmental parameters overlapped. We found no significant differences in species richness, density, and assemblage composition of butterflies between management decisions. However, changes in local environmental conditions, such as an increase in the coverage of understory vegetation, increased the abundance of butterflies.
4. Synthesis and applications: Our findings suggest that replanting oil palm and choice of mono or polyculture have relatively few effects on butterflies, but management for specific features in plantations could benefit butterfly assemblages
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The effects of land-use change on semi-aquatic bugs (Gerromorpha, Hemiptera) in rainforest streams in Sabah, Malaysia
1. Land-use change and agricultural expansion have caused marked biodiversity loss in Southeast Asia, but impacts on freshwater communities have been very little studied. Semi-aquatic bugs are abundant in streams, provide prey for many other animals, and are sensitive to environmental change, making them a relevant group for studying land-use change.
2. We investigated the effects of logging and conversion of forest to oil palm plantations on semi-aquatic bugs in Sabah, Malaysia, and the potential value of retaining riparian buffer strips in plantations, by sampling across 12 rivers along an existing land-use gradient. We recorded catchment, riparian, and stream-scale environmental variables and surveyed semi-aquatic bugs within streams in old-growth forest, logged forest, and oil palm plantation with (OPB) and without buffer strips (OP). We recorded the abundance, richness, total biomass, and proportion of juveniles and winged adult individuals of all species, together with the sex ratio of a common morphospecies (Ptilomera sp.), as possible indicators of disturbance effects.
3. Average abundance and average richness, but not total biomass, of all semi-aquatic bugs were lower in areas with higher habitat disturbance. In particular, average abundance in old-growth forest was more than twice, four, and six times higher than that in logged forest, OPB, and OP, respectively. Average richness in old-growth forest was higher than in logged forest by two species, but more than twice and three times higher than in OPB and OP, respectively.
4. The presence of riparian buffer strips in oil palm had little effect on the abundance and richness of semi-aquatic bugs. We found no significant differences in the proportion of juveniles, winged adult individuals, or the sex ratio of Ptilomera sp. along the disturbance gradient.
5. In conclusion, oil palm plantations were associated with lower average abundance and richness of semi-aquatic bugs than forest sites, but community composition did not differ markedly between logged and old-growth forests. We also found that the forested buffer strips maintained within our oil palm plantation study sites did not protect forest species of semi-aquatic bugs. Maintaining forest may therefore provide the best option for the conservation of semi-aquatic bugs, but further studies of the effects of land-use change and management options are needed across Southeast Asia
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Lengthâbiomass equations to allow rapid assessment of semi-aquatic bug biomass in tropical streams
Funder: Cambridge Trust; Id: http://dx.doi.org/10.13039/501100003343Funder: Cambridge University Commonwealth FundFunder: Hanne and Torkel WeisâFogh FundFunder: Jardine FoundationFunder: Panton TrustFunder: ProforestFunder: S.T. Lee FundFunder: Tim Whitmore FundFunder: Varley Gradwell Travelling Fellowship1. Length-biomass equations are relatively easy and cost-effective for deriving insect biomass. However, the exact relationship can vary between taxa and geographical regions.
2. Semi-aquatic bugs are abundant and are indicators of freshwater quality, but there are no studies investigating the effect of habitat disturbance on their biomass, although it is useful in assessing ecological processes.
3. We identified the best-fit length-biomass models to predict the biomass of semi-aquatic bugs (Gerromorpha, Hemiptera) collected from streams in Sabah, Malaysia.
4. We used 259 juvenile and adult semi-aquatic bugs to compare a range of plausible length-biomass functions, and to assess whether relationships differed across the following families and body forms: a.Cylindrostethinae, Gerrinae, and Ptilomerinae, which are subfamilies within Gerridae consisting of small to large bugs that have long and slender bodies, b. Halobatinae, a subfamily within Gerridae, consisting of small to medium-sized bugs with wide heads and thoraxes as well as short abdomens, and c. Veliidae, which are small bugs with stout bodies.
5. Estimation used five fitting functions (linear regression; polynomial regression order two, three, and four; and power regression) on the following groupings: three body forms combined; each body form with life stages (juvenile and adult) combined; and each body form with life stages separated.
6. Power regressions were the best fit in predicting the biomass of semi-aquatic bugs across life stages and body forms, and the predictive power of models was higher when the biomass of different body forms was calculated separately (specifically for Halobatinae and Veliidae). Splitting by life stages did not always result in additional improvement.
7. The equations from this study expand the scope of possible future ecological research on semi-aquatic bugs, particularly in Southeast Asia, by allowing more studies to consider biomass-related questions.Jardine Foundation, the Cambridge Trust, Proforest, the Varley Gradwell Travelling Fellowship, the Tim Whitmore Fund, the Panton Trust, the Cambridge University Commonwealth Fund, the Hanne and Torkel Weis-Fogh Fund, the S.T. Lee Fun