Mapping the structure of Borneo's tropical forests across a degradation gradient

South East Asia has the highest rate of lowland forest loss of any tropical region, with logging and deforestation for conversion to plantation agriculture being flagged as the most urgent threats. Detecting and mapping logging impacts on forest structure is a primary conservation concern, as these impacts feed through to changes in biodiversity and ecosystem functions. Here, we test whether high-spatial resolution satellite remote sensing can be used to map the responses of aboveground live tree biomass (AGB), canopy leaf area index (LAI) and fractional vegetation cover (FCover) to selective logging and deforestation in Malaysian Borneo. We measured these attributes in permanent vegetation plots in rainforest and oil palm plantations across the degradation landscape of the Stability of Altered Forest Ecosystems project. We found significant mathematical relationships between field-measured structure and satellite-derived spectral and texture information, explaining up to 62% of variation in biophysical structure across forest and oil palm plots. These relationships held at different aggregation levels from plots to forest disturbance types and oil palms allowing us to map aboveground biomass and canopy structure across the degradation landscape. The maps reveal considerable spatial variation in the impacts of previous logging, a pattern that was less clear when considering field data alone. Up-scaled maps revealed a pronounced decline in aboveground live tree biomass with increasing disturbance, impacts which are also clearly visible in the field data even a decade after logging. Field data demonstrate a rapid recovery in forest canopy structure with the canopy recovering to pre-disturbance levels a decade after logging. Yet, up-scaled maps show that both LAI and FCover are still reduced in logged compared to primary forest stands and markedly lower in oil palm stands. While uncertainties remain, these maps can now be utilised to identify conservation win–wins, especially when combining them with ongoing biodiversity surveys and measurements of carbon sequestration, hydrological cycles and microclimate

Firefly distribution and abundance on mangrove vegetation assemblages in Sepetang estuary, Peninsular Malaysia

Pteroptyx fireflies are commonly reported to congregate in large numbers in mangroves. Not much is known about the relationships between firefly distribution and abundance with specific mangrove vegetation assemblages. We conducted a study to investigate the vegetation assemblages that structure the distribution and abundance of Pteroptyx tener in Peninsular Malaysia. The distribution and abundance of fireflies were assessed along an 8 km stretch of mangroves in Sepetang estuary using visual assessment. Statistical analysis was carried out to test the correlation between length of display section and percentage cover of P. tener colonies and the relationship between percentage cover of fireflies with different vegetation assemblages. Five distinct vegetation assemblages were identified comprising different combination of four mangrove species. It was found that shorter display sections had higher percentage cover of P. tener colonies. In addition, vegetation assemblage which consisting of mainly Sonneratia caseolaris and Nypa fruticans was the most preferred type. The results of this study point to the necessity to consider not only a single mangrove species but the entire vegetation assemblage for firefly conservation

Thresholds for adding degraded tropical forest to the conservation estate

Logged and disturbed forests are often viewed as degraded and depauperate environments compared with primary forest. However, they are dynamic ecosystems1 that provide refugia for large amounts of biodiversity2,3, so we cannot afford to underestimate their conservation value4. Here we present empirically defined thresholds for categorizing the conservation value of logged forests, using one of the most comprehensive assessments of taxon responses to habitat degradation in any tropical forest environment. We analysed the impact of logging intensity on the individual occurrence patterns of 1,681 taxa belonging to 86 taxonomic orders and 126 functional groups in Sabah, Malaysia. Our results demonstrate the existence of two conservation-relevant thresholds. First, lightly logged forests (68%) of their biomass removed, and these are likely to require more expensive measures to recover their biodiversity value. Overall, our data confirm that primary forests are irreplaceable5, but they also reinforce the message that logged forests retain considerable conservation value that should not be overlooked

Length–biomass 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 Weis‐Fogh 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

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

Tropical forest fragments contribute to species richness in adjacent oil palm plantations

In Southeast Asia, large-scale conversion of rainforest to oil palm plantations is one of the major causes of biodiversity declines. Recommendations for reducing species losses and increasing the sustainability of palm oil production advocate the retention of natural forest patches within plantations, but there is little evidence for the effectiveness of this strategy. Here, we examine to what extent rainforest remnants with different characteristics contribute to biodiversity within surrounding plantations. We sampled ground-dwelling ants in Sabah (Malaysian Borneo) using unbaited pit-fall traps along 1. km transects spanning forest-plantation ecotones of 10 forest fragments (area 5. ha-500. ha) and two continuous forest sites which bordered plantations. Ant species richness in plantations varied according to richness in adjacent forest fragments, which increased with fragment size. A trend of declining species richness in plantations with distance from the forest ecotone was consistent with spillover of forest species into plantations adjacent to forest remnants. Ant assemblages in plantations also contained more carnivorous species adjacent to large forest fragments, suggesting large fragments may have benefits for pest control in plantations, as well as benefits for local biodiversity. Our results indicate that large forest fragments support distinctive ant assemblages and increase diversity within the planted area, but small fragments (<~200. ha) contribute little to plantation diversity. Thus retaining large fragments of forest may help mitigate the loss of species within oil palm plantations