Tropical Forestry

Smallholder eucalyptus growers’ perception of the causes and symptoms of soil degradation in Central Vietnam

Thinh Trieu Dang — 2026-06-24

This study investigates local perceptions of soil degradation in eucalyptus plantations in Central Vietnam, where rapid plantation expansion has raised concerns about long‑term environmental sustainability. Using semi‑structured interviews and focus group discussions with 60 plantation growers, the study reveals an almost universal perception of soil decline: 93.3% of respondents reported degradation and 87.5% rated its severity as moderate or severe. Farmers identified monoculture forestry as the principal anthropogenic driver (87.5%), together with management practices such as clear‑cutting, residue burning, short rotation cycles, and removal of harvest residues. Reported manifestations of degradation included reduced forest productivity (100% of respondents), soil compaction and loss of friability, decreased surface organic matter, rapid soil drying, and increased erosion. While natural factors such as intense and irregular rainfall were acknowledged as contributing to degradation, respondents emphasized that human management plays the decisive role, implying that soil decline can be mitigated through improved silvicultural practices. The findings highlight the importance of integrating local ecological knowledge with scientific evidence to design multi‑level management strategies aimed at restoring soil health, enhancing the sustainability of eucalyptus plantation systems, and supporting rural livelihoods in Central Vietnam.

Impact of tree age and grain orientation on the shrinkage and swelling of Acacia mangium wood from Sabah, Malaysia

Thamer A Thabet Thabet — 2026-05-27

The aim of this study was to determine the impact of tree age and grain orientation on the shrinkage and swelling of Acacia mangium wood. The specimens from eight ages of tree 3, 5, 7, 9, 11, 13, and 15 year-old were tested for water absorption, swelling, shrinkage, Volumetric Shrinkage and Swelling according to the ASTM D 143-94. Results show that Acacia mangium wood swells in both radial and tangential directions, indicating that a linear relationship can be established with increasing water content over time. At a grain angle of β = 90.0°, a significant negative correlation (R² = 0.98) was observed between the percentage of dimensional change and longitudinal shrinkage. There was no strong correlation (R² = 0.50) between the longitudinal swelling time and the dimensional change. However, a relationship (R² = 0.66) was indicated between the percentage of tangential and radial swelling over time at an angle of β = 0.0°. Additionally, it was investigated that the tangential shrinkage percentage of Acacia mangium wood increased from 0.10% to 2.758%, while the radial shrinkage increased from 0.095% to 2.385%. The longitudinal shrinkage increases dramatically from 1.548% to 3.105%. Micrograph images obtained using scanning electron microscopy (SEM) and 3D optical microscopy were included in this study to improve the results by offering detailed visual insights into fibre orientation and the structure of the cell wall.

Diel activity pattern of mousedeer in response to human activity at Kinarut Eco Forest Park

Andy Russel Mojiol — 2026-04-04

The fragmented lowland forest of Kinarut Eco Forest Park, which serves as a habitat for mousedeer (Tragulus spp.), is heavily impacted by human activity, though the extent of its impact on this species remains unexplored. This study conducted a camera trap survey at 20 systematically established sampling points along local gravel roads and forest trails to examine the diel activity pattern of mousedeer in response to human activity on these pathways. Over 1,275 nights of camera trapping, 43 independent detections of mousedeer and 302 independent sightings of humans were documented. The present findings validated that mousedeer exhibited a nocturnal behavior, while humans showed a diurnal behavior, contributing to a very low similarity in their diel activity patterns along local human pathways (∆₁ = 0.1086). The observed temporal partitioning between humans and mousedeer highlights the ability of this terrestrial mammal species to adapt to disturbances resulting from frequent human visits to these pathways, as well as the prominent impact of high human activity levels, which have triggered the shift from crepuscular to nocturnal behavior in mousedeer within the fragmented lowland forest ecosystem of this reserve.

Visitor insects of Ooia spp. (Araceae) at Kinabalu UNESCO Global Geopark, Sabah, Malaysia

Mohd Naufal Wafi Jimran — 2026-01-30

The study was conducted at Kinabalu UNESCO Global Geopark (Kinabalu Geopark), Sayap Substation and Poring Substation to study the visiting insect’s interactions with two species of Ooia (Araceae). This study aimed to observe and identified the visitor insects for both Ooia species, analyzed the overlap of visiting insects between the two plant species of Ooia sayapensis and O. kinabaluensis, and to determine the difference in the number of the two species receiving visits from insects. Total of 124 individual insects were recorded, consists of six families including Staphylinidae, Erotylidae, Blattidae, Formicidae, Vespidae, and Drosophilidae. The Wilcoxon data analysis showed no significant difference (p>0.05) for the overlap of visiting insects in the two species of Ooia. However, the number of insect visits on O. sayapensis Kartini was higher (Day-1= 32% and Day-2= 33%) than O. kinabaluensis (Bogner) S.Y.Wong & P.C.Boyce (Day-1= 23% and Day-2= 16%) respectively. The difference of insect visitation rates between the two Ooia species suggest there is multiple factors influence their ability to attract insects. This study will add fundamental data on visitor insects of Ooia sayapensis within its habitat.

Spatial distribution and visitor satisfaction in a low-visitation protection forest in northern Borneo, Malaysia

Nur Atiqah Ag Damit — 2026-04-09

The aim of the study was to examine the spatial distribution, travel distance effects, and visitor satisfaction patterns associated with the Taliwas River Conservation Area (TRCA) in Sabah, Malaysia. Taliwas River Conservation Area (TRCA) was the study area located in Lahad Datu Districts, Sabah, Malaysia. Visitor data from 2011 to 2017 were analyzed by district of origin to assess spatial trends and distance decay using regression analysis. A structured questionnaire was distributed via social media to assess visitor experiences and satisfaction (n = 30). Most visitors originated from nearby districts, especially Lahad Datu (44.8%). Travel distance had a strong inverse effect on visitor number (R² = 0.6752). Visitor feedback indicated high appreciation for natural features (e.g., waterfalls, Pandan Lake), occasional wildlife encounters, and service quality. Cleanliness of facilities and staff friendliness were commonly mentioned as contributing to a positive experience. Spatial proximity is the dominant factor shaping visitor distribution in the TRCA, but demand and group visits from urban institutions can offset distance effects. Visitor experiences centered on natural features, occasional wildlife sightings, and service quality, underscoring key areas for improving low-visitation protected areas.

Riparian soil and hydrological variations in Imbak Canyon and SFERA@UMS under contrasting tropical forest land-uses

Nurul Fatihah — 2026-04-09

This study presents a comparative baseline assessment of soil characteristics and hydrological properties across three riparian forest types in Sabah, Malaysia: Primary Forest (PF), Old Regrowth Forest (ORF), and Logged Forest (LF). Conducted in the Imbak Canyon Conservation Area and SFERA@UMS, measurements focused on soil texture, bulk density, soil moisture, and unsaturated hydraulic conductivity. PF and ORF exhibited higher clay content, greater soil moisture retention, and moderate infiltration rates, indicating superior hydrological function. In contrast, LF plots, dominated by sandier textures and reduced canopy cover, showed lower moisture retention and markedly diminished hydraulic conductivity. While bulk density patterns did not strictly follow expected trends—PF and ORF had slightly higher mean values than LF—results may reflect natural variability and structural recovery stages. Relationships between soil texture and hydrological parameters highlight the influence of disturbance and forest regeneration on riparian ecohydrology. The study provides essential baseline data for future monitoring, reinforces the ecological value of undisturbed and recovering forests, and supports the prioritization of PF and ORF zones in riparian buffer planning and watershed conservation.

Camera-trap insights into wildlife diversity in SFERA@UMS urban forest, Sabah

Jephte Sompud — 2026-04-21

Urban forest remnants contribute to biodiversity conservation in rapidly developing cities. The Sustainable Forest for Education and Research Area (SFERA@UMS), a 25-ha forest fragment within Universiti Malaysia Sabah, has undergone restoration, but information on its wildlife is limited. We conducted a camera-trap survey from April to September 2023 to document mammals and birds present in the area. Nine camera traps were deployed continuously and periodically relocated, generating 1,620 camera-trap nights. Seven wildlife species were detected, including six mammals and one bird. Long-tailed macaques (Macaca fascicularis; Endangered) accounted for the majority of detections, indicating high tolerance to urban disturbance. The confirmed presence of the Critically Endangered Sunda pangolin (Manis javanica), along with the Greater mousedeer (Tragulus napu) and Asian palm civet (Paradoxurus hermaphroditus), highlights the ecological importance of this small forest patch. These results provide baseline data and demonstrate that small forest remnants, such as SFERA@UMS, remain vital refuges for wildlife in Kota Kinabalu.