Biology subjects

Sheil, D.

Publications and source records attributed to Sheil, D..

7 recordsLinked to original sources

bioRxiv2025

Predictors of extinction risk in large tropical forest mammals: from global to local

Studies can only guide conservation if their findings are informative at the scales at which practitioners and policymakers operate. Yet, it is rarely tested whether large-scale studies reach similar conclusions to the smaller-scale studies on which conservation traditionally relies. We examine whether predictors of extinction risk are consistent across global, regional, and local scales, for 210 tropical forest mammal species ([≥] 1 kg) that existed during the last 130,000 years, in 64 tropical forests, across three biogeographical realms. We found consistent predictors of extinction risk (body mass, generation length, diet, brain volume and scansoriality) when analyses differed only in their spatial resolution. However, predictors differed when analyses also varied in their temporal extent. Macroecological findings about extinction risk can, thus, inform conservation at smaller scales, but they risk misidentifying threatened species if differences in temporal extent are not recognised.

ecology↗

bioRxiv2025

Lightning-caused disturbance frequency and severity varies with topography in an Afromontane forest

Lightning is an important agent of tropical tree mortality, but we know little about lightning-caused disturbances beyond one lowland tropical forest in Panama. Here we quantified variation in the frequency and severity of visually-detectable lightning-caused disturbances across topography in the montane forests of Nyungwe National Park, Rwanda. This was the first systematic assessment of lightning-caused disturbance in Africa and a preliminary test of the hypothesis that forest tolerance to lightning is higher where lightning disturbances are more common. Lightning-caused disturbances were observed six-times more frequently on ridges than in valleys, but lightning-caused disturbances in valleys tended to cause more tree-level damage than those on ridges. Overall, lightning disturbances tended to kill a lower proportion of trees in this Afromontane forest than in previously documented lightning disturbances in tropical America. We also observed less tree-level damage to Syzygium spp.(Myrtaceae) compared to the community-wide average, providing support for taxonomic differences in lightning tolerance. Our results indicate that lightning disturbance severity differs within and among sites, mediated in part by differences in lightning tolerance among tree species, and provide some support for the hypothesis that disturbance severity declines with disturbance frequency.

ecology↗

bioRxiv2025

Forest structure, timber species regeneration, and timber volume dynamics along a logging gradient in a lowland tropical rainforest in Africa: Implications for biodiversity conservation and sustainable timber management

Timber production, cutting and extraction is impacting vast areas of tropical forests, highlighting the need for management strategies to promote sustainable recovery of logged forests. However, limited information is available on how logging and enrichment planting affect forest structure, commercial tree species, and timber volume recovery. In this study, we assessed the effects of timber cutting and extraction ("logging") on forest structure, regeneration of key timber species, and volume recovery across different logging intensities. We compared the effects of enrichment planting, initiated over 60 years ago, versus natural regeneration on timber volume recovery of Khaya anthotheca (Welw.) C.DC., a highly targeted species. We inventoried all live stems with a diameter at breast height (DBH) of [≥]2 cm across 9 compartments using 45 plots of 0.5 ha each: heavily logged forests (25 plots, totaling 12.5 ha), lightly logged forests (15 plots, totaling 7.5 ha), and unlogged forest (5 plots, totaling 2.5 ha). Our results suggest that timber production has impacted on tree regeneration of harvested timber species such Entandrophragma species, Milicia excelsa (Welw.) C. Berg, Olea capensis L. subsp. welwitschii (Knobl.) Friis & Green and Ricinodendron heudelotii (Baill.) Heckel; Timber volume recovery of harvested species was 61.3% lower in heavily logged and 51.7% lower in lightly logged forests compared to unlogged forest. Stem density, basal area, and timber volume recovery of mahogany species were influenced by time since last logging. Notably, heavily logged forest that were enriched with K. anthotheca had significantly higher stem density and timber volumes of this species compared to logged forests without such enrichment. In conclusion, our study suggests that passive regeneration in Budongos logged compartments has been inadequate for achieving timber volume recovery of high-value commercial species. If an economic assessment proves favorable we recommend further trials of enrichment planting of high-value timber species (Mahogany spp., Milicia excelsa, and Olea capensis) alongside fast-growing species (Maesopsis eminii Engl., Albizia spp.). As well as Reduced Impact Logging and broader species selection from classes II and III, to reduce damage and enhance timber yields in production forests.

ecology↗

bioRxiv2024

The moon's influence on the activity of tropical forest mammals

Changes in lunar illumination alter the balance of risks and opportunities for animals at night, influencing activity patterns and species interactions. Our knowledge about behavioral responses to moonlight is incomplete, yet it can serve to assess and predict how species respond to environmental changes such as light pollution or loss of canopy cover. As a baseline, we wish to examine if and how wildlife responds to the lunar cycle in some of the darkest places inhabited by terrestrial mammals: the floors of tropical forests. We quantified the prevalence and direction of activity responses to the moon in tropical forest mammal communities. Using custom Bayesian multinomial logistic regression models, we analyzed long-term camera trapping data on 88 mammal species from 17 protected forests on three continents. We also tested the hypothesis that nocturnal species are more prone to avoiding moonlight, as well as quantified diel activity shifts in response to moonlight. We found that, apparent avoidance of moonlight (lunar phobia, 16% of species) is more common than apparent attraction (lunar philia, 3% of species). The three species exhibiting lunar philia followed diurnal or diurnal-crepuscular activity patterns. Lunar phobia, detected in 14 species, is more pronounced with higher degree of nocturnality, and is disproportionately common among rodents. Strongly lunar phobic species were less active during moonlit nights, which in most cases also decreases their total daily activity. Our findings indicate that moonlight influences animal behavior even beneath the forest canopy. This suggests that such impacts may be exacerbated in degraded and fragmented forests. Additionally, the effect of artificial light on wild communities is becoming increasingly apparent. Our study offers empirical data from protected tropical forests as a baseline for comparison with more disturbed areas, together with a robust approach for detecting activity shifts in response to environmental change. Open Research statement: The data and code for performing the analyses described in this article are available at https://github.com/richbi/TropicalMoon.

ecology↗

bioRxiv2022

Global disparity of research allocation and the Aichi biodiversity conservation targets

Tracking progress towards global biodiversity conservation targets requires appropriate allocation of research and monitoring efforts. We conducted a global review of camera trap research on mammals as a proxy for biodiversity research and monitoring over the last two decades. We assessed how 3395 research locations from 2324 studies tracked priority regions for attaining the 2020 Aichi Biodiversity Targets. We used a geospatial distribution modelling approach to predict the spatial allocation of biodiversity research and to identify its key drivers. We show that conservation research in the past two decades has often failed to target areas important for conservation, and that 76.8% of the global research allocation can be attributed to country income, biome, mammal richness and accessibility. We predicted lowest probabilities of research allocation in low income countries. The Amazon and Congo Forest basins -- two highly biodiverse ecosystems facing unprecedented human alteration -- received inadequate research attention. Even in the most researched regions, an average of 51.4% of the research locations were outside the top 20% most important areas for the global biodiversity Aichi Targets. To support biodiversity conservation targets, policy and practice, more research and monitoring is required in regions with high importance for conservation.

ecology↗

bioRxiv2021

Forest loss in Indonesian New Guinea: trends, drivers, and outlook

The rich forests of Indonesian New Guinea are threatened. We used satellite data to examine annual forest loss, road development and plantation expansion from 2001 to 2019, then developed a model to predict future deforestation in this understudied region. In 2019, 34.29 million hectares (Mha), or 83% of Indonesian New Guinea, supported old-growth forest. Over nineteen years, two percent (0.75 Mha) were cleared: 45% (0.34 Mha) converted to industrial plantations, roads, mine tailings, or other uses near cities; 55% (0.41 Mha) cleared by transient processes including selective natural timber extraction, inland water bodies-related processes, fires, and shifting agriculture. Industrial plantations expanded by 0.23 Mha, with the majority (0.21 Mha; 28% of forest loss) replacing forests and reaching 0.28 Mha in 2019 (97% oil palm; 3% pulpwood). The Trans-Papua Highway, a ~4,000 km national investment project, increased by 1,554 km. Positive correlations between highway and plantations expansion indicate these are linked processes. Plantations and roads grew rapidly after 2011, peaked in 2015/16, and declined thereafter. Indonesian government allocated 2.62 Mha of land for the development of industrial plantations (90% oil palm 10% pulpwood) of which 74% (1.95 Mha) remained forest in 2019. A spatial model predicts that an additional 4.5 Mha of forest could be cleared by 2036 if Indonesian New Guinea follows similar relationships to Indonesian Borneo. We highlight the opportunities for policy reform and the importance of working with indigenous communities, local leaders, and provincial government to protect the biological and cultural richness still embodied in this remarkable region.

ecology↗

bioRxiv2018

Biological control protects tropical forests

Biological control of invasive species can restore crop yields, and thus ease land pressure and contribute to forest conservation. In this study, we show how biological control against the mealybug Phenacoccus manihoti (Hemiptera) slowed deforestation across Southeast Asia. In Thailand, the newly-arrived mealybug caused an 18% decline in cassava yields over 2009-2010, a shortfall in national production and an escalation in the price of cassava products. This spurred an expansion of cassava cropping in neighboring countries from 713,000 ha in 2009 to >1 million ha by 2011: satellite imagery reveal 388%, 330%, 185% and 608% increases in peak deforestation rates in Cambodia, Lao PDR, Myanmar and Viet Nam focused in cassava crop expansion areas. Following release of the host-specific natural enemy Anagyrus lopezi (Hymenoptera) in 2010, mealybug outbreaks were reduced, cropping area contracted and associated deforestation slowed by 31-94% in individual countries. When used with due caution and according to current guidelines, biological control offers broad benefits for people and the environment.

ecology↗