Forests Of Southeast Asia Research Articles

Impacts of climate change on reproductive phenology in tropical rainforests of Southeast Asia

In humid forests in Southeast Asia, many species from dozens of plant families flower gregariously and fruit synchronously at irregular multi-year intervals1–4. Little is known about how climate change will impact these community-wide mass reproductive events. Here, we perform a comprehensive analysis of reproductive phenology and its environmental drivers based on a monthly reproductive phenology record from 210 species in 41 families in Peninsular Malaysia. We find that the proportion of flowering and fruiting species decreased from 1976 to 2010. Using a phenology model, we find that 57% of species in the Dipterocarpaceae family respond to both drought and low-temperature cues for flowering. We show that low-temperature flowering cues will become less available in the future in the RCP2.6 and 8.5 scenarios, leading to decreased flowering opportunities of these species in a wide region from Thailand to the island of Borneo. Our results highlight the vulnerability of and variability in phenological responses across species in tropical ecosystems that differ from temperate and boreal biomes.

Spatial patterns and drivers of smallholder oil palm expansion within peat swamp forests of Riau, Indonesia

Protecting the tropical peat swamp forests in Southeast Asia is critical for addressing global sustainability challenges such as climate change and biodiversity loss. However, more than half of these forests have been lost since 1990 due to the rapid expansion of drainage-based agriculture and forestry. Within the oil palm sector, the number of regional smallholder oil palm plantings on peat soils has risen quickly. These activities are challenging to govern and manage, due to their fragmented nature and the numerous farmers involved. It is imperative to understand the spatial distribution and drivers of the smallholder oil palm-related conversion of peat swamp forests. In contrast to existing studies based on farm surveys, we used state-of-art maps of smallholder oil palm plantings, derived from 2019 remote sensing data. Spatial data about socioeconomic and biophysical factors (e.g. mills, roads, water ways, and concessions) was then used to develop logistic regression models to investigate the relative influence of these factors. We show that the spatial patterns of smallholder oil palm plantings are distinct from those of industrial oil palm plantations, revealing the critical roles of roads, especially service roads, residential roads and tracks, in driving smallholder oil palm expansion within peatlands. We found that 90% of smallholder oil palm areas were located within 2 km of roads and 25 km of mills. The mean likelihood of a given land area being converted from peat swamp forests to smallholder oil palm declined rapidly with increasing distance from roads and mills. In addition to roads and mills, land use zones (e.g. the setting of concessions and migration settlements) and other environmental factors (e.g. precipitation and elevation) were identified as important drivers of smallholder oil palm expansion on peatland. Based on these findings, we identify priority regions for the protection of the remaining peat swamp forests in Indonesia and discuss strategies for tackling these sustainability challenges on local and global scales.

Tetracera loureiri Extract Regulates Lipopolysaccharide-Induced Inflammatory Response Via Nuclear Factor-κB and Mitogen Activated Protein Kinase Signaling Pathways.

Tetracera loureiri (T. loureiri) is a woody climber inhabiting open deciduous or evergreen forests in Southeast Asia. A decoction comprising its stem and other herbs is a traditional Thai remedy for fatigue and jaundice, as well as to promote overall health. Anti-inflammatory effects induced by T. loureiri extract have not been reported. In this study, we investigated the anti-inflammatory effect of an ethanol extract of T. loureiri (ETL) on lipopolysaccharide (LPS)-induced inflammatory response in RAW264.7 macrophages. We found that ETL treatment inhibited the production of nitric oxide (NO) in LPS-stimulated RAW264.7 cells, without affecting cell viability. The effect of ETL on the expression of various pro-inflammatory mediators was analyzed using reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and enzyme-linked immunosorbent assay (ELISA). We observed that ETL inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the mRNA and protein levels and decreased the production of prostaglandin E2 (PGE2) by COX-2 in RAW264.7 macrophages. ETL dose-dependently reduced the production of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in LPS-induced RAW264.7 cells, in a dose-dependent manner. Furthermore, ETL suppressed the LPS-induced nuclear translocation of the nuclear factor, NF-κB. Additionally, ETL was found to inhibit the activation of mitogen-activated protein kinases (MAPK), such as extracellular signal-regulated kinase, c-Jun-N-terminal kinase, and p38 MAPK. In conclusion, our findings demonstrate that ETL inhibits the expression of pro-inflammatory mediators and cytokines, thereby downregulating NF-κB and MAPK signaling pathways in LPS-stimulated macrophages, Consequently, ETL is a potential therapeutic agent for the treatment of inflammatory diseases.

Tree regeneration characteristics in limestone forests of the Cat Ba National Park, Vietnam

BackgroundThe ability of overstory tree species to regenerate successfully is important for the preservation of tree species diversity and its associated flora and fauna. This study investigated forest regeneration dynamics in the Cat Ba National Park, a biodiversity hotspot in Vietnam. Data was collected from 90 sample plots (500 m2) and 450 sub-sample plots (25 m2) in regional limestone forests. We evaluated the regeneration status of tree species by developing five ratios relating overstory and regeneration richness and diversity. By examining the effect of environmental factors on these ratios, we aimed to identify the main drivers for maintaining tree species diversity or for potential diversity gaps between the regeneration and the overstory layer. Our results can help to increase the understanding of regeneration patterns in tropical forests of Southeast Asia and to develop successful conservation strategies.ResultsWe found 97 tree species in the regeneration layer compared to 136 species in the overstory layer. The average regeneration density was 3764 ± 1601 per ha. Around 70% of the overstory tree species generated offspring. According to the International Union for Conservation of Nature’s Red List, only 36% of threatened tree species were found in the regeneration layer. A principal component analysis provided evidence that the regeneration of tree species was slightly negatively correlated to terrain factors (percentage of rock surface, slope) and soil properties (cation exchange capacity, pH, humus content, soil moisture, soil depth). Contrary to our expectations, traces of human impact and the prevailing light conditions (total site factor, gap fraction, openness, indirect site factor, direct site factor) had no influence on regeneration density and composition, probably due to the small gradient in light availability.ConclusionWe conclude that the tree species richness in Cat Ba National Park appears to be declining at present. We suggest similar investigations in other biodiversity hotspots to learn whether the observed trend is a global phenomenon. In any case, a conservation strategy for the threatened tree species in the Cat Ba National Park needs to be developed if tree species diversity is to be maintained.

Comparative population genomics reveals glacial cycles to drive diversifications in tropical montane birds (Aves, Timaliidae)

Many bird species are specialized to live in the broadleaved, evergreen forests in the mountain regions in Southeast Asia. These mountain habitats are not continuously distributed as the different mountain areas are separated by lowlands, which has restricted gene flow and thus contributed to the high biological diversity in this region. The degree of connectivity between mountain areas has fluctuated with the Pleistocene glacial cycles, being largest during the glaciations when the mountain forests spread to lower elevations. Here we study how the intermittent periods of restricted gene flow and connectivity between the populations of five montane species of babblers (Aves, Timaliidae) in Vietnam may be traced in their genomes. The results suggest that the babbler species in the Central Highlands have been isolated from their sister-populations in northern Vietnam for between ca. 585 and 380 ky. For two species with populations in both the Central Highlands and the Da Lat region, we found that these split at more or less the same time (440–340 kya). We also found a significant statistical correlation between the time of the splits of these populations and the lowest altitude at which they are known to occur (no similar correlation was found with the geographic distances between populations). The populations in northern Vietnam show higher genetic variation than their counterparts in South-Central Vietnam, supporting the postulate that smaller populations may have lower genetic variation than larger. In accordance with this, we found the lowest genetic variation in the two species with the smallest populations in the Central Highlands. These two populations also show low levels of genomic heterozygosity. Our results show that the south-central populations of the studied babbler species are genetically distinct from their sister-populations in northern Vietnam, providing additional argument for the long-term protection of the evergreen mountain forests in Southeast Asia.

Forest biosecurity laws in South-East Asia: a review

To ensure the protection of natural and planted forests in South-East Asia, it is vital that the risks posed by invasive and local pests are minimised and that effective mitigation and response plans are in place. To do so, forest biosecurity laws need to be developed to coordinate policy, direct on-ground activities to prepare the region to respond to an incursion and empower relevant agencies to act. In this review, we outline the current laws and legislations relevant to the forestry sector in six ASEAN countries and make suggestions on forest biosecurity laws that could be developed. We put forward general recommendations on how these laws may be developed, with a focus on a regional approach to forest biosecurity. This could be implemented through the formation of a forest biosecurity working group as a sub-committee to the ASEAN Forest Products Industry Club, to promote global safety in invasive pests of native and planted forests of member countries.

Historical data guides restoration of degraded peat swamp forests in Southeast Asia

Peat swamp forests in Southeast Asia are under heavy pressure. Deforestation, forest degradation, wildfires, and drainage have damaged or destroyed substantial areas of the once extensive peat swamp forest formations. Several efforts are underway to rehabilitate degraded peat forests areas in order to restore some of the valuable ecosystem services these forested areas once provided. However, these efforts often result in (mixed)-plantations that only partly resemble the original peat forests. Information about these peat swamp forests’ complex origin and ecology is needed to improve restoration outcomes further. Our paper analyses historical data from coastal peat swamp forests in Sarawak and Brunei and discusses the potential to use this as the reference value for intact peat forests. We describe the observed stand structure and species composition for pristine peat swamp forest, and we analyze the population structure of three dominant peat swamp forest species: Gonystylus bancanus (ramin), Dactylocladus stenostachys (jongkong) and Shorea albida (alan batu). We compare the historical data with data from recently measured, degraded peat swamp forests. We discuss our results in relation to processes of peat dome formation, nutrient availability and hydrology, and give recommendations for peat swamp forest management and restoration.

The genome of Shorea leprosula (Dipterocarpaceae) highlights the ecological relevance of drought in aseasonal tropical rainforests

Hyperdiverse tropical rainforests, such as the aseasonal forests in Southeast Asia, are supported by high annual rainfall. Its canopy is dominated by the species-rich tree family of Dipterocarpaceae (Asian dipterocarps), which has both ecological (e.g., supports flora and fauna) and economical (e.g., timber production) importance. Recent ecological studies suggested that rare irregular drought events may be an environmental stress and signal for the tropical trees. We assembled the genome of a widespread but near threatened dipterocarp, Shorea leprosula, and analyzed the transcriptome sequences of ten dipterocarp species representing seven genera. Comparative genomic and molecular dating analyses suggested a whole-genome duplication close to the Cretaceous-Paleogene extinction event followed by the diversification of major dipterocarp lineages (i.e. Dipterocarpoideae). Interestingly, the retained duplicated genes were enriched for genes upregulated by no-irrigation treatment. These findings provide molecular support for the relevance of drought for tropical trees despite the lack of an annual dry season.

Courtship and underwater communication in the Sunda gharial (Tomistoma schlegelii)

ABSTRACT Many threatened crocodilians are shy and difficult to observe in the wild, limiting the current knowledge of their behaviour and ecology. Although acoustic communication is commonly used by adults during courtship and territory defence, the signals produced vary between taxa. Here we provide the first classification of adult vocalisations in Tomistoma schlegelii – a rare gavialid inhabiting swamp forests in Southeast Asia – and describe the behaviour produced during courtship. Using video and passive underwater acoustic monitoring we recorded a breeding captive pair of T. schlegelii housed indoors, as well as monitored 12 captive adults kept in a semi-natural outdoor enclosure over a period of two months. Courtship behaviour during 18 recorded mating events followed that observed in other crocodilians, but acoustic signals were restricted to mating activity and were only recorded in the two animals housed indoors. We identified seven signal types produced by T. schlegelii, which differed in duration, dominant frequency, and the presence of harmonic structure. These results suggest the species uses short-range, underwater acoustic signals during courtship and mating, with little vocal activity outside of those events, and provide foundation for future studies of this rare crocodilian.

Mapping smallholder forest plantations in Andhra Pradesh, India using multitemporal harmonized landsat sentinel‐2 S10 data

AbstractThis study's objective was to develop a method by which smallholder forest plantations can be mapped accurately in Andhra Pradesh, India, using multitemporal visible and near‐infrared (VNIR) bands from the sentinel‐2 multispectral instruments (MSIs). Conversion to cropland, coupled with secondary dependencies on and scarcity of wood products, has driven the deforestation and degradation of natural forests in Southeast Asia. Concomitantly, forest plantations have been established both within and outside of forests, with the latter (as contiguous blocks) and are the focus of this study. Accurately mapping smallholder forest plantations in South and Southeast Asia is difficult using remotely sensed data due to the plantations' small size (average of 2 hectares), short rotation ages (4–7 years for timber species), and spectral similarities to croplands and natural forests. Cloud‐free Harmonized landsat sentinel‐2 (HLS) S10 data were acquired over six dates, from different seasons, over four years (2015–2018). Available in situ data on forest plantations was supplemented with additional training data resulting in 2230 high‐quality samples aggregated into three land cover classes: nonforest, natural forest, and forest plantations. Image classification used random forests on a thirty‐band stack consisting of the VNIR bands and NDVI images for all six dates. The median classification accuracy from the 5‐fold cross‐validation was 94.3%. Our results, predicated on high‐quality training data, demonstrate that (mostly smallholder) forest plantations can be separated from natural forests even using only the sentinel‐2 VNIR bands when multitemporal data (across both years and seasons) are used.

Conservation status of Southeast Asian natural habitat estimated using Galliformes spatio-temporal range decline

Southeast Asia has arguably the highest biodiversity loss due to the high deforestation rate and hunting pressure. In the region, 55 species of the family Phasianidae can be found in all available land habitats from lowland plains up to high-elevation mountainous areas. As ground-dwelling birds, these species are sensitive to habitat disturbance and hunting pressure, making them ideal to evaluate the status of remaining Southeast Asian forest habitats. The aims of this work are, therefore, to define for each Phasianidae species: (1) the extent of forest cover, suitable habitat and large forest patches currently available in the region and their decline over the years between 2000 and 2018 (six estimated generations) and (2) assess the threats using a Bayesian Belief Network approach combining data on forest loss hotspots and hunting pressure. Moreover, we defined the spatial distribution of Phasianidae diversity hotspots and relative threats in the region. The results show that over the 18-year study period, the forest cover, suitable habitat and Phasianidae diversity in Southeast Asia declined overall. The remaining forest habitats currently have low species diversity and face medium to high threat levels from habitat loss and hunting pressure. Population monitoring and higher protection levels both inside and outside protected areas are essential for the species’ long term survival. We recommend using Phasianidae as indicator species to monitor the overall habitat conservation status in Southeast Asia.

Timber production and carbon emission reductions through improved forest management and substitution of fossil fuels with wood biomass

Global efforts have been made to manage tropical forests for timber production and climate change mitigation. This study assessed carbon emission reductions through the improved forest management and the substitution of fossil fuels with wood biomasses under the conventional (CVL) and reduced impact logging (RIL) systems in Southeast Asia between 2000 and 2060. During this period, carbon emissions from logging and deforestation in the region were approximately 10% of carbon emissions from tropical deforestation. By adopting the RIL, 96.6 Tg CO2 of emissions can be reduced, while producing 35.1 million m3 year−1 of wood products. If woody biomasses are used to substitute the combustion of coal, diesel, or natural gas for bioenergy production, total emission reductions could be 229.9, 215.4, or 207.9 Tg CO2 annually during the Paris Agreement, respectively. Depending on chosen carbon price, management of natural forests in Southeast Asia could generate about US$2.1–2.3 billion annually over 10 years between 2020 and 2030. Although costs for bioenergy production from wood biomass remain the concern, enabling global policies, emerging sustainability markets, and financial incentives through carbon tax, environmental tax, and energy tax could materialize the sound management of tropical forests for long-term timber production and climate change mitigation.

Predicting carbon emissions, emissions reductions, and carbon removal due to deforestation and plantation forests in Southeast Asia

Periodic assessment of the forest carbon stocks is needed as part of the global efforts to reduce deforestation and forest degradation and mitigate climate change. Here, we assessed carbon stocks, carbon emissions, removals, and reductions due to deforestation and management of the natural (NFs) and plantation forests (PFs) in Southeast Asia. We found that area of NFs declined about 1.09 million ha or 0.52% yr−1 over the last 20 years but only approximately 0.29 million ha was converted to PFs. Between 2000 and 2030, Southeast Asia emitted 477.7 TgCO2 yr−1 from NFs but gained 44.0 TgCO2 yr−1 in PFs. As area of production forest continues to decline, future timber production in the region is likely to come from the PFs. Using the retrospective approach, forest reference emission level in Southeast Asia was estimated at 431.2 TgCO2 yr−1 during the implementation period of the Paris Agreement between 2020 and 2030. If REDD+ activities were implemented to reduce deforestation and forest degradation and enhance forest carbon stocks, 1922.1 TgCO2 of carbon credits could be achieved and the net carbon revenues were US$8–180 billion between 2020 and 2030 depending on the chosen carbon prices.

Evaluation of Motor Coordination and Antidepressant Activities of Cinnamomum osmophloeum ct. Linalool Leaf Oil in Rodent Model.

Cinnamomum plants (Lauraceae) are a woody species native to South and Southeast Asia forests, and are widely used as food flavors and traditional medicines. This study aims to evaluate the chemical constituents of Cinnamomum osmophloeum ct. linalool leaf oil, and its antidepressant and motor coordination activities and the other behavioral evaluations in a rodent animal model. The major component of leaf oil is linalool, confirmed by GC-MS analysis. Leaf oil would not induce the extra body weight gain compared to the control mice at the examined doses after 6 weeks of oral administration. The present results provide the first evidence for motor coordination and antidepressant effects present in leaf oil. According to hypnotic, locomotor behavioral, and motor coordination evaluations, leaf oil would not cause side effects, including weight gain, drowsiness and a diminishment in the motor functions, at the examined doses. In summary, these results revealed C. osmophloeum ct. linalool leaf essential oil is of high potential as a therapeutic supplement for minor/medium depressive syndromes.

Increase in social interactions of wild Northern Gray gibbons (Hylobates funereus) during the mast fruiting period in the Danum Valley Conservation Area, Sabah, Malaysia

In Southeast Asian forests, there are dramatic supra-annual peaks in fruit availability known as mast fruiting, followed by low-fruit periods. Gibbons are frugivorous small apes. In this study, we investigated how gibbons varied their social and calling behaviors in response to changes in fruit availability. Activity budget, travel distance, sleeping time, and song duration of two wild Northern Gray gibbon (Hylobates funereus) groups were investigated during both mast and non-mast fruiting periods at the Danum Valley Conservation Area, Sabah, Malaysia. Gibbons traveled longer, entered the sleeping tree later, and spent more time engaged in singing, playing, and grooming behaviors during the mast fruiting period. Playing and grooming are intra-group social interactions. Gibbon songs were sung antiphonally within and among groups, indicating that singing is both an intra- and inter-group social interaction. Furthermore, copulatory behaviors that occurred during female pregnancy were observed during the mast fruiting period, suggesting this might be a social interaction behavior rather than a reproductive activity. Our results show that gibbons extended their daily activity schedules during the mast fruiting period and spent this extra time on social interactions. We examined whether male song complexity increased during the mast fruiting period by using the Levenshtein distance method, but we did not find such a trend. In the mast fruiting period, gibbons may consume more energy than in the non-mast fruiting period. Social and calling behaviors are energetically costly. Our results show that there is a link between energy intake and social and calling behaviors.

Dinomyrmex gigas (Latreille, 1802): A Potential Icon for Taman Negara Johor Endau Rompin

Dinomyrmex gigas (Latreille, 1802) is one of the largest ants in the world and the largest in Southeast Asia. It is also more commonly known as the giant forest ant. This large charismatic ant can be found in the forests of Southeast Asia, however it is not often sighted by the public due to its predominant nocturnal nature. Despite being considerably well studied compared to its smaller counterparts, most people know little about the giant forest ant beyond its large size. Most studies on this species focus on the populations found in Malaysia and Brunei characterizing many aspects of the natural history and biology of this species including its foraging behaviour, diet, territoriality, reproduction and colony structure. While much is known about the biology of this species, fragmented forest habitats may have an impact on the viability and behaviour of this majestic giant ant of the forest. This study involved insects’ viability observation and sampling of ant specimens. The results of observations showed that D. gigas is viable in Endau Rompin Johor National Park (TNJER). Then, various ecological aspects of D. gigas was investigated through field studies and secondary information. Due to its size and uniqueness this species has a potential to be developed into a nature tourism product for Malaysia. The present study elaborated to further discover its daily activity, nesting and defence behaviour which could be useful in developing it into a nature tourism product. As the species is also limited in distribution to undisturbed forest, the issue of its survival is discussed with relation to conservation of the tropical rainforest.

東南アジア熱帯林の哺乳類（2）ボルネオ島の有蹄類

東南アジア熱帯林の哺乳類（2）ボルネオ島の有蹄類

New allometric equations for quantifying tree biomass and carbon sequestration in seasonally dry secondary forest in northern Thailand

As tropical deforestation and forest degradation accelerate, carbon-credit trading could provide a financial incentive to preserve and regenerate forests. Since carbon trading relies on the accurate quantification of carbon stocks, allometric equations are urgently needed to derive above-ground dry biomass (AGB) from easily measured variables. Few allometric equations have been published for regenerating secondary forests in Southeast Asia. This study established new allometric equations, to determine AGB and carbon in regenerating secondary forests on shifting cultivation fallows in northern Thailand. To develop the equations, data were collected from 78 trees (136 felled individual stems, including coppices) ranging in size from 1 to 32.9 cm diameter at breast height (D). The dependent variable was AGB. The independent variables were D, tree height (H) and wood density (WD). Wood density varied significantly among species (p < 0.05). Consequently, including WD in the function D2H × WD predicted AGB most accurately, compared with other functions that excluded it. Mean carbon concentration in stems, branches, and leaves was 44.84% ± 1.63 of dry mass, but it varied significantly among tree species (p < 0.05). The new allometric equation revealed that tree ABG was highest in secondary forest, followed by the 7-year-fallow and the 4-year-fallow: 105.3, 38.3 and 10.3 Mg ha−1, respectively, while above-ground carbon was 47.7, 17.4, and 4.6 Mg C ha−1, respectively. Natural regeneration accumulated carbon slower than reported for active restoration, suggesting that managed restoration is preferable to passive regeneration on fallows in northern Thailand. The allometric equations, derived from this study, can be used to accurately determine tree ABG and carbon storage in regenerating secondary forest, with higher precision than has hitherto been possible, thus satisfying the monitoring requirements of REDD+ and other carbon-trading schemes.

東南アジア熱帯林の哺乳類（4）リス類の進化的歴史と生態 多様多彩なリス類の創出機構を考える

東南アジア熱帯林の哺乳類（4）リス類の進化的歴史と生態 多様多彩なリス類の創出機構を考える

Drivers of Bornean Orangutan Distribution across a Multiple-Use Tropical Landscape

Logging and conversion of tropical forests in Southeast Asia have resulted in the expansion of landscapes containing a mosaic of habitats that may vary in their ability to sustain local biodiversity. However, the complexity of these landscapes makes it difficult to assess abundance and distribution of some species using ground-based surveys alone. Here, we deployed a combination of ground-transects and aerial surveys to determine drivers of the critically endangered Bornean Orangutan (Pongo pygmaeus morio) distribution across a large multiple-use landscape in Sabah, Malaysian Borneo. Ground-transects and aerial surveys using drones were conducted for orangutan nests and hemi-epiphytic strangler fig trees (Ficus spp.) (an important food resource) in 48 survey areas across 76 km2, within a study landscape of 261 km2. Orangutan nest count data were fitted to models accounting for variation in land use, above-ground carbon density (ACD, a surrogate for forest quality), strangler fig density, and elevation (between 117 and 675 m). Orangutan nest counts were significantly higher in all land uses possessing natural forest cover, regardless of degradation status, than in monoculture plantations. Within these natural forests, nest counts increased with higher ACD and strangler fig density, but not with elevation. In logged forest (ACD 14–150 Mg ha−1), strangler fig density had a significant, positive relationship with orangutan nest counts, but this relationship disappeared in a forest with higher carbon content (ACD 150–209 Mg ha−1). Based on an area-to-area comparison, orangutan nest counts from ground transects were higher than from counts derived from aerial surveys, but this did not constitute a statistically significant difference. Although the difference in nest counts was not significantly different, this analysis indicates that both methods under-sample the total number of nests present within a given area. Aerial surveys are, therefore, a useful method for assessing the orangutan habitat use over large areas. However, the under-estimation of nest counts by both methods suggests that a small number of ground surveys should be retained in future surveys using this technique, particularly in areas with dense understory vegetation. This study shows that even highly degraded forests may be a suitable orangutan habitat as long as strangler fig trees remain intact after areas of forest are logged. Enrichment planting of strangler figs may, therefore, be a valuable tool for orangutan conservation in these landscapes.