Understanding how selective logging affects biodiversity is crucial to planning cost-effective conservation strategies in tropical forests, yet there is limited understanding of its impacts on fauna functional diversity in the tropical Americas. We assessed how selective logging intensification and time since logging influence multiple metrics of fauna functional integrity in the Brazilian Amazon by collecting bird and dung beetle data within 48 logging management units that had experienced varying exploitation intensities between 1.5–2.0 and 5.0–6.0 years before the faunal surveys. We investigated assemblage responses and used functional attributes to assess changes in functional diversity, specialization, originality and species rarity. Using point counts and pitfall traps, we collected 5081 records of 182 bird species and 7892 dung beetles from 45 species. Logging intensification led to significant declines in most dung beetle responses and bird body mass, whereas time since logging was a key driver of dung beetle and bird functional and taxonomic diversity. Our study presents novel empirical evidence of how logging intensification effects vary across taxa, ecological metrics and time since logging, which is key to informing forest conservation and further investigating environmental degradation impacts on tropical biodiversity.

The prehensile-tailed skink Corucia zebrata is endemic to the Solomon Islands. It is the most traded reptile from the country. During 2000–2019, CITES reported the legal export of 10,567 individuals. Although the level of this trade is well documented, impacts on the skink's survival in its native range are comparatively unknown. During January–May 2020, we surveyed 146 people on 12 islands to collect information on the habitats preferred by the prehensile-tailed skink, to understand perceptions of the species' conservation status and identify any potential threats. Respondents reported lowland and hill forests as being favoured habitats, with low proportions of respondents identifying coastal and montane forests as suitable habitat. Habitat loss (72%), hunting (17%), and predation (6%) were identified as the main threats. People younger than 30 years of age reported killing the skinks more frequently than did people over the age of 30. Prehensile-tailed skinks have a relatively small home range, long reproductive cycle, and are vulnerable to numerous threats. We thus recommend a halt to the current practice of exporting wild-caught prehensile-tailed skinks, and replacement by a well-regulated captive breeding programme.

Selective logging in tropical forests may lead to deforestation and forest degradation, so accurate mapping of it will assist in forest restoration, among other ecological applications. This study aimed to track canopy tree loss due to illegal logging of the important hardwood tree Ocotea usambarensis in a closed-canopy submontane tropical forest by evaluating the mapping potential of the very-high-resolution WorldView-3 multispectral dataset using random forest (RF) and support vector machine (SVM) with radial basis function kernel classifiers. The results show average overall accuracies of 92.3 ± 2.6% and 94.0 ± 2.1% for the RF and SVM models, respectively. Average kappa coefficients were 0.88 ± 0.03 for RF and 0.90 ± 0.02 for SVM. The user’s and producer’s accuracies for both classifiers were in the range of 84–100%. This study further indicates that vegetation indices derived from bands 5 and 6 helped detect canopy gaps in the study area. Both variable importance measurement in the RF algorithm and pairwise feature selection proved useful in identifying the most pertinent variables in the classification of canopy gaps. These findings could allow forest managers to improve methods of detecting canopy gaps at larger scales using remote sensing data and relatively little additional fieldwork.

Research demonstrates substantial urban consumption of wildmeat and the existence of trade networks in the Brazilian Amazon. Yet rural–urban mobility persists in this urbanized region, with the circulation of people, goods and ideas, blurring boundaries between rural and urban lives. Here we examined the relationships between rural–urban mobility and wildmeat access in highly forested areas of central Brazilian Amazonia. We surveyed 798 urban households in four towns and 311 rural households in 63 riverine communities. Rural–urban mobility was common amongst urban households: 49.7% maintained rural livelihoods and 57.3% were headed by rural in-migrants. Although many urban consumers purchased wildmeat, gifting was equally important. Urban households with greater rural–urban mobility consumed more wildmeat and were less likely to purchase it. Buying wildmeat was rare in rural areas but emergent in larger rural communities. Rural consumption was greater in remote areas, non-floodplain communities and during the high-water season. Urban populations placed particular pressure on three preferred species: the lowland paca Cuniculus paca, tapir Tapirus terrestris and white-lipped peccary Tayassu pecari. Rural consumption was more diverse, and per-capita wildmeat consumption was four times greater in rural than urban households (21 vs 5 kg/person/year). Total estimated annual wildmeat consumption was 3,732 t across 43 riverine urban centres compared to 11,351 t in surrounding rural areas. Because of poverty in these towns and socially mediated wildmeat acquisition, it is debatable whether urban consumers should or could be denied access to wildmeat. Nonetheless, the probable future increase in urban demand and related risks to sustainable, equitable resource use necessitate the monitoring and management of rural–urban wildmeat flows.

Litter production plays an important role in the functioning of the ecosystem, providing several ecosystem services, such as nutrients cycling and carbon storage. We studied litter production patterns and its relationship with forest structure over a chronosequence of secondary forests in southern Bahia, Brazil. In the study area, 15 pairs of mature and secondary forest were used, in a chronological sequence, being 10, 25 and 40-year-old secondary forests and mature forests. Plots were created for the collection of aboveground biomass data, and within these plots, litter collectors were installed and monitored for 1 year. The results showed that litter production was lower in 10-year-old secondary forests when compared with older forests. On the other hand, in the 10-year-old forests, annual litter production represents 47.8% of the stored biomass, while in mature forests annual litter production represents only 4%. We found that structural variables (basal area, number of stems and canopy opening) influence significantly litter production, as well as litter as percentage of forest biomass. The study emphasizes the importance of biomass production through litterfall in regenerating tropical forests, and its importance for carbon storage and for the maintenance of ecosystem services.

Land-use changes and forest management decisions can profoundly alter soil organic carbon (SOC) stocks. Therefore, the objective of this study was to investigate whether existing SOC stocks in the forests of Singapore can be related to successional stages of forest vegetation following disturbances. A forest classification system was developed using information about land use history and vegetation data from 21 inventory plots collected within the framework of Singapore’s IPCC-compatible greenhouse gas reporting system. The forest successional classes obtained were related to SOC stocks (0–50 cm) determined on the same plots. The inventory plots were assigned to four classes. Primary forests (Class 1) were dominated by late succession native species. Secondary forests representing natural forest succession (Class 2) contained younger native trees and a few large trees. Secondary forests after tree plantation/fruit orchard (Class 3) and after agricultural crop cultivation (Class 4) were characterised by large proportions of exotic tree species. Maximum stocks of SOC declined from Class 1 (127.7 Mg ha−1) to Class 4 (35.2 Mg ha−1). The results of a principal component analysis confirmed our forest classification. Plant-related parameters can be successfully used to classify the forests in Singapore, which also show clear differences in SOC.

This study quantified CO2 emissions from tropical peat swamp soils in Brunei Darussalam. At each site, soil was collected from areas of intact and degraded peat and CO2 flux, and total organic content were measured ex situ. Soil organic content (~20–99%) was not significantly different between intact and degraded forest samples. CO2 flux was higher for intact forest samples than degraded forest samples (~1.0 vs. ~0.6 μmol CO2 m−2 s−1, respectively) but did not differ among forest locations. From our laboratory experiments, we estimated a potential emissions of ~10–20 t CO2 ha−1 y−1 which is in the lower range of values reported for other tropical peat swamps. However, our results are likely affected by unmeasured variation in root respiration and the lability of resident carbon. Overall, these findings provide experimental evidence to support that clearance of tropical peat swamp forests can increase CO2 emissions due to faster rates of decomposition.

Paramos are high-elevation tropical Andean ecosystems above the tree line that display variable temperature and frequent freezing spells. Because a significant anuran community lives in this environment, physiological protection against freezing must characterise individuals in this community. Antifreeze protection has been studied in amphibians from other communities, and it is likely that Paramo anurans rely on the same underlying molecules that convey such protection to Nearctic species. However, given the pervasive presence of freezing spells in the Paramos year-round, the processes of activating protection mechanisms may differ from that of seasonal counterparts. Accordingly, this study investigated cryoprotection strategies in high-elevation tropical frogs, using as a model the terrestrial and nocturnal genus Pristimantis, specifically P. bogotensis, P. elegans and P. nervicus from Paramos, and the warm ecosystem counterparts P. insignitus, P. megalops and P. sanctaemartae. We focused on freeze tolerance and its relationship with glucose accumulation and ice formation. Under field conditions, the highest elevation P. nervicus exhibited higher glucose concentration at dawn compared to noon (1.7 ± 0.6 mmol/L versus 3.5 ± 1.32 mmol/L). Under experimental thermal freeze exposure for 2 hours between −2 and −4 ºC, the glucose concentration of the three Paramo species increased but physiological diversity was evident (P. nervicus 126%; P. bogotensis 100%; and P. elegans 55%). During this test, body ice formation was assessed calorimetrically. The species with the highest body ice formation was P. bogotensis (17% ± 5.37; maximum value: 63%; n = 8), followed by P. nervicus (5% ± 3.27; maximum value: 11%; n = 5) and P. elegans (0.34% ± 0.09; maximum value: 1%; n = 4). The study shows physiological diversity both within a genus and across the amphibian community around the freezing contour. Overall, Paramo species differ in freezing physiology from their low-elevation counterparts. Thus, climate shifts increasing freezing spells may affect the structure of communities in this zone.

Corticolous lichens in the central mountains of Sri Lanka differ with vegetation type, disturbance and climate. All growth forms of lichens were studied in 42 plots (six plots × seven vegetation types), yielding 124 species. Lichen species diversity varied with number of tree species per plot (correlations) and differed with disturbance group, vegetation type and climate zone (general linear models). Lichen community composition (estimated cover of 74 species each at ≥ 3 plots) varied along two ordination gradients secondarily correlated with disturbance (nonmetric multidimensional scaling, NMS). Undisturbed and disturbed plots (mostly grouped by vegetation type) were divided along NMS axis 1, correlating with distance to undisturbed forest. Longest-disturbed plots differed from all others along NMS axis 2 and were correlated with canopy cover. Climate was weakly reflected on the ordination as the proximity of two plot clusters in montane vegetation types. Indicator species analyses (ISA) of lichen cover by plot identified 60 strong indicator species (indicator value ≥ 50%, P < 0.015). Fifty-seven species were indicators for individual vegetation types (28 of them for undisturbed types); three were for a disturbance group only; 11 were also for a disturbance group or climate zone. Most species strongly driving ordination patterns were also ISA indicators. Most lichens were crustose (39, with 24 in the Graphidaceae). Each vegetation type had at least one indicator with trentepohliod algae (increasing for undisturbed plots) and one with chlorococcoid algae. Two visually distinct indicator species, three genera and two multi-genus groups will be useful to parataxonomists in forest evaluation.

In Africa, the early Holocene was characterized by wetter, warmer conditions than today, followed by rapid aridification at ~5.2 ka. However, a lack of lowland vegetation records has prevented a detailed evaluation of forest response to Holocene climate change. Additionally, although modern vegetation communities are linked to human disturbance, few studies have addressed how prehistoric human activities helped engineer the character of modern African ecosystems. Understanding the architecture of lowland and highland forests is important to prevent further degradation from climate/land-use change. We present an 11,000 yr fossil pollen record from Lake Edward, Uganda. We show that Guineo-Congolian forests dominated the highlands and lowlands in equatorial East Africa in the early Holocene, highlighting the importance of rainfall and temperature in controlling forest communities. These forests remained until ~5.2 ka, when the climate became drier. The lacustrine ecosystem response to aridification was abrupt; however, forest decreased gradually, replaced by deciduous woodlands. Woodlands dominated until after an arid period at 2 ka; however, forest did not recover. Increased disturbance indicators and grasses suggest that the arrival of Iron Age people resulted in the modern fire-tolerant vegetation. Although late Holocene climate played a role in vegetation opening, the modern ecosystem architecture in East Africa is linked to early human activities.

The effects of fragmentation and overstorey tree diversity on tree regeneration were assessed in tropical rain forests of the Western Ghats, India. Ninety plots were sampled for saplings (1–5 cm diameter at breast height (dbh); 5×5-m plots) and overstorey trees (>9.55 cm dbh; 20×20-m plots) within two fragments (32 ha and 18 ha) and two continuous forests. We tested the hypotheses that fragmentation and expected seed-dispersal declines (1) reduce sapling densities and species richness of all species and old-growth species, and increase recruitment of early-successional species, (2) reduce the prevalence of dispersed recruits and (3) increase influence of local overstorey on sapling densities and richness. Continuous forests and fragments had similar sapling densities and species richness overall, but density and richness of old-growth species declined by 62% and 48%, respectively, in fragments. Fragments had 39% lower densities and 24% lower richness of immigrant saplings (presumed dispersed into sites as conspecific adults were absent nearby), and immigrant densities of old-growth bird-dispersed species declined by 79%. Sapling species richness (overall and old-growth) increased with overstorey species richness in fragments, but was unrelated to overstorey richness in continuous forests. Our results show that while forest fragments retain significant sapling diversity, losses of immigrant recruits and increased overstorey influence strengthen barriers to natural regeneration of old-growth tropical rain forests.

Environmental conditions of the lowland tropical forests during the last glacial maximum (LGM) between ca 20,000 and 18,000 14C yr B.P., are reevaluated in terms of dating control and lithology analyzed in seven pollen records from South America. The reevaluation shows that probably in none of the published records are LGM sediments present or abundant. This conclusion is based on the occurrence of abrupt lithologic changes coupled with changes in sedimentation rate interpolated from radiocarbon dates. These findings suggest that the LGM was represented probably by a hiatus of several thousand years, indicative of drier climates than before or after.

We studied the relationship between flower size and nectar properties of hummingbird-visited flowers in the Brazilian Atlantic Forest. We analysed the nectar volume and concentration as a function of corolla length and the average bill size of visitors for 150 plant species, using the phylogenetic generalized least squares (PGLS) to control for phylogenetic signals in the data. We found that nectar volume is positively correlated with corolla length due to phylogenetic allometry. We also demonstrated that larger flowers provide better rewards for long-billed hummingbirds. Regardless of the causal mechanisms, our results support the hypothesis that morphological floral traits that drive partitioning among hummingbirds correspond to the quantity of resources produced by the flowers in the Atlantic Forest. We demonstrate that the relationship between nectar properties and flower size is affected by phylogenetic constraints and thus future studies assessing the interaction between floral traits need to control for phylogenetic signals in the data.

This article discusses how biological conservation can benefit from an understanding of soil carbon. Protecting natural areas not only safeguards the biota but also curtails atmospheric carbon emissions. Opportunities for funding biological conservation could potentially be greater if soil carbon content is considered. In this article current knowledge concerning the magnitude and vulnerability of soil carbon stocks is reviewed and the relationship of these stocks to biological conservation values is explored. Looking at two relatively well-studied tropical regions we find that 15 of 21 animal species of conservation concern in the Virunga Landscape (Central Africa), and nine of ten such species in the Federal District of Brazil (Central Brazil), rely on carbon-rich habitats (alluvial and/or wetlands). At national scales, densities of species, endemics and threatened taxa (plants, mammals, birds, reptiles, amphibians and fish) show positive and significant relations with mean soil carbon content in all but two cases (threatened amphibians and threatened fish). Of more than 1000 threatened species in 37 selected tropical nations, 85% rely on carbon-rich habitats. This tendency is observed in plants, mammals, reptiles, amphibians and crustaceans, while birds appear more evenly distributed. Research to clarify and explore these relationships is needed. Soil carbon offers major opportunities for conservation.

Rigorous population studies on many small carnivores are lacking in India. Presence-absence models with habitat covariates were applied to estimate seasonal occupancy and abundance of nine small-carnivore species from camera-trap data in Mudumalai Tiger Reserve (2010 and 2011). We deployed 25 camera-trap stations in the deciduous forest, 21 in the semi-evergreen forest and 26 in the dry thorn forest. In total, 7380 trap-nights yielded 448 photographs of small carnivores: jungle cat (n = 72), leopard cat (n = 6), rusty-spotted cat (n = 11), small Indian civet (n = 89), common palm civet (n = 37), brown palm civet (n = 20), stripe-necked mongoose (n = 66), ruddy mongoose (n = 96) and Indian grey mongoose (n = 51). In the dry season, rusty-spotted cat was the rarest carnivore with an average abundance (λmean) of 0.24 ± 0.26, while ruddy mongoose was the most abundant (λmean = 0.90 ± 0.40). In the wet season, leopard cat was the rarest species (λmean = 0.048 ± 0.041) while grey mongoose was the most abundant (λmean = 0.68 ± 0.35). Abundance of jungle cat, common palm civet, ruddy mongoose and grey mongoose increased in the dry thorn forest whereas in the dry season abundance of small Indian civet decreased in this forest type. Abundance of leopard cat and small Indian civet was not influenced by habitat in the wet season. Deciduous forest was positively associated with abundance of rusty-spotted cat. Deciduous and semi-evergreen forests had a positive effect on abundance of stripe-necked mongoose while the latter was a positive predictor of abundance and occupancy for brown palm civet. Improved modelling approaches can account for the spatio-temporal variation in habitat use of small carnivores occupying specialized niches in heterogeneous tropical forests of southern India.

Tropical forests are both important stores of carbon and among the most biodiverse ecosystems on the planet. Reducing emissions from deforestation and degradation (REDD) schemes are designed to mitigate the impacts of climate change, by conserving tropical forests threatened by deforestation or degradation. REDD schemes also have the potential to contribute significantly to biodiversity conservation efforts within tropical forests, however biodiversity conservation and carbon sequestration need to be aligned more closely for this potential to be realized. This paper analyses the relationship between tree species diversity and above-ground biomass (AGB) derived from 1-ha tree plots in Central African rainforests. There was a weakly significant correlation between tree biomass and tree species diversity (r = 0.21, p = 0.03), and a significantly higher mean species diversity in plots with larger AGB estimates (M = 44.38 species in the top eight plots, compared to M = 35.22 in the lower eight plots). In these Central African plots, the relationship between tree species diversity and AGB appeared to be highly variable; nonetheless, high species diversity may often be related to higher biomass and, in such cases, REDD schemes may enhance biodiversity by targeting species diverse forests.

Understanding the role that protected areas play in the livelihood security of local communities is essential to ensure that local people are not left shouldering the costs of what is a public good, and to help maintain robust local and national constituencies for biodiversity conservation. To provide baseline data for a longitudinal study on the effects of newly established national parks on human livelihoods in Gabon we conducted a cross-sectional study that compared livelihood indicators between communities that do, and do not, use natural resources within protected areas. We interviewed 2,035 households in 117 villages at four sites, recording income, consumption, education, health indicators and social capital, and village characteristics such as distance to markets, distance to park boundaries, and land cover within a 5-km radius. Our results indicated that closed rainforest coverage was greater around park than control villages and that this difference was associated with a greater reliance of park households on forest resources. However, we found no systematic differences in most livelihood measures between park and control households. Instead, the relationship between household livelihood measures and proximity to parks varied in idiosyncratic ways between sites, suggesting that determinants of human welfare are highly localized and cannot be generalized to larger spatial scales.

Tropical forest management is a quintessential interdisciplinary (ID) problem straddling the social-natural divide, and has attracted scholars from many disciplines. This paper is a review of the ID research on tropical forests with a view to understanding the challenges involved in doing ID environmental research in general and the manner in which they might be addressed. Research on two core interdisciplinary questions in tropical forest research, namely causes of tropical forest loss and degradation and its impacts on society, is analysed to illuminate issues facing ID researchers. The challenges stem from differences in implicit values, theories and epistemologies across disciplines, as well as the relationship between individual disciplines, the ID space and the wider applied research audience. Understanding the value-laden nature of terms such as forest loss and degradation leads to a multidimensional and multidisciplinary characterization of the impact of forest change on human well-being. The analysis of causes of change has been enriched by ID research in which forest outcomes are characterized explicitly in terms of their values, measured in terms relevant to these values and linked to chains of socioeconomic variables at the appropriate scale. Explanations from different disciplines may be reconciled to some extent by seeing each as partial and perhaps having context-specific validity, although some core tensions, especially between economists and anthropologists, remain. Insights from ID research have been unevenly internalized in the literature, pointing to the absence of a broadly shared ID space as a consequence of individual social science disciplines appropriating environment as a subject of study. Shifting from theory-driven to problem-driven research and re-engaging self-consciously in this applied ID space will be required to generate more rigorous and relevant ID research on forests.

Most research on attitudes to parks in sub-Saharan Africa has been in savannah regions and areas of low population density. Expulsion, exclusion and the imposition of external control are dominant themes, resulting in negative responses to parks, particularly those that represent hard-edged so-called fortress conservation. Our research in the densely populated area around a mid altitude forest park in western Uganda found an alternate narrative in which, despite its hard-edged fortress features, most people view Kibale National Park favourably. Based on a geographically random sample in two agricultural areas neighbouring the Park, our results indicate that most households felt they benefit from the Park and only a small proportion cited negative impacts. Rather than direct economic returns, the benefits most commonly noted by respondents can be characterized as ecosystem services. Most individual respondents and a large majority of the local political leaders said that the Park should continue to exist. Crop raiding by animals from the Park is a problem in some locations but resource restrictions and expulsion were not widely cited by our respondents. The fact that the large majority of residents migrated to the area after the Park was established may be an important explanatory factor for these responses, and this is also likely to be the case for many other mid altitude tropical forest parks, the demographic and land-use histories of which differ from those around many savannah parks.