1. There is a weak evidence base supporting the effective management of riparian ecosystems within tropical agriculture. Policies to protect riparian buffers-strips of non-cultivated land alongside waterways-are vague and vary greatly between countries.2. From a rapid evidence appraisal, we find that riparian buffers are beneficial to hydrology, water quality, biodiversity and some ecosystem functions in tropical landscapes. However, effects on connectivity, carbon storage and emissions reduction remain understudied. Riparian functions are mediated by buffer width and habitat quality, but explicit threshold recommendations are rare. Policy implications.A one-size fits all width criterion, commonly applied, will be insufficient to provide all riparian functions in all circumstances. Context-specific guidelines for allocating, restoring and managing riparian buffers are necessary to minimise continued degradation of biodiversity and ecosystem functioning in tropical agriculture.

Conservation planning tends to focus on protecting species' ranges or landscape connectivity but seldom both-particularly in the case of diverse taxonomic assemblages and multiple planning goals. Therefore, information on potential trade-offs between maintaining landscape connectivity and achieving other conservation objectives is lacking. We developed an optimization approach to prioritize the maximal protection of species' ranges, ecosystem types, and forest carbon stocks, while also including habitat connectivity for range-shifting species and dispersal corridors to link protected area. We applied our approach to Sabah, Malaysia, where the state government mandated an increase in protected-area coverage of approximately 305,000 ha but did not specify where new protected areas should be. Compared with a conservation planning approach that did not incorporate the 2 connectivity features, our approach increased the protection of dispersal corridors and elevational connectivity by 13% and 21%, respectively. Coverage of vertebrate and plant species' ranges and forest types were the same whether connectivity was included or excluded. Our approach protected 2% less forest carbon and 3% less butterfly range than when connectivity features were not included. Hence, the inclusion of connectivity into conservation planning can generate large increases in the protection of landscape connectivity with minimal loss of representation of other conservation targets.

Sabah in Malaysian Borneo contains a range of diverse ecosystems and some of the richest concentrations of biodiversity in the world. Yet the state's existing protected area network is too fragmented and of insufficient size to safeguard biodiversity in the long term. Experts have emphasised the need for a landscape level approach to shore up conservation areas through the creation of ecological corridors of compatible mixed use. In light of the 2003 Durban Accord which signalled a shift towards greater levels of community participation in conservation, this article features the efforts made by the state to explore the potential role of Indigenous and Community-Conserved Areas (ICCAs) in strengthening biodiversity conservation. Selected case studies are used to showcase some of the ways ICCAs are already making important contributions to safeguarding ecological services and maintaining habitat connectivity in the state. Recognising the role of indigenous and local communities in sustaining Sabah's unique biocultural landscapes is a critical component of a long-term approach to sustaining irreplaceable natural heritage. Sabah's legal framework actually contains sufficient provision for greater synergy between community and statebased governance of biodiversity areas, yet aspects of Sabah's political economy must be addressed before this ideal can be realised.

Rain forests on Borneo support exceptional concentrations of endemic insect biodiversity, but many of these forest‐dependent species are threatened by land‐use change. Totally protected areas (TPAs) of forest are key for conserving biodiversity, and we examined the effectiveness of the current TPA network for conserving range‐restricted butterflies in Sabah (Malaysian Borneo). We found that mean diurnal temperature range and precipitation of the wettest quarter of the year were the most important predictors of butterfly distributions (N = 77 range‐restricted species), and that species richness increased with elevation and aboveground forest carbon. On average across all species, TPAs were effective at conserving ~43% of species’ ranges, but encompassed only ~40% of areas with high species richness (i.e., containing at least 50% of our study species). The TPA network also included only 33%–40% of areas identified as high priority for conserving range‐restricted species, as determined by a systematic conservation prioritization analysis. Hence, the current TPA network is reasonably effective at conserving range‐restricted butterflies, although considerable areas of high species richness (6,565 km2) and high conservation priority (11,152–12,531 km2) are not currently protected. Sabah's remaining forests, and the range‐restricted species they support, are under continued threat from agricultural expansion and urban development, and our study highlights important areas of rain forest that require enhanced protection. Abstract in Malay is available with online material.

Agricultural expansion is the primary driver of ecological degradation across the tropics. Set-asides—uncultivated parts of agricultural landscapes, often on steep slopes and alongside rivers—may alleviate environmental impacts but can reduce the area cultivated. Here we model an approach to configuring set-asides aimed at optimizing ecological outcomes (biodiversity, above-ground carbon storage and nutrient cycling) without reducing net cultivation area. We compare set-asides in an oil palm landscape where all plantations adopt the same configuration (‘uniform’ approach) with a scenario where there can be variation in configuration among plantations (‘variable’ approach). We find that all set-aside configurations support substantial ecological values but that the best strategies involve set-asides, particularly alongside rivers, that are spatially targeted and variable among plantations. This ‘variable’ approach can increase ecological outcomes twofold over the ‘uniform’ approach without reducing net cultivation area. Our findings underscore the potential importance of well-planned set-asides for enhancing agricultural sustainability.