• Journal of Ecology and Environment
• /
• v.44 no.2
• /
• pp.81-89
• /
• 2020

In the forest ecosystems, litterfall is an important component of the nutrient cycle that regulates the accumulation of soil organic matter (SOM), the input and output of the nutrients, nutrient replenishment, biodiversity conservation, and other ecosystem functions. Therefore, a profound understanding of the major processes (litterfall production and its decomposition rate) in the cycle is vital for sustainable forest management (SFM). Despite these facts, there is still a limited knowledge in tropical forest ecosystems, and further researches are highly needed. This shortfall of research-based knowledge, especially in tropical forest ecosystems, may be a contributing factor to the lack of understanding of the role of plant litter in the forest ecosystem function for sustainable forest management, particularly in the tropical forest landscapes. Therefore, in this paper, I review the role of plant litter in tropical forest ecosystems with the aims of assessing the importance of plant litter in forest ecosystems for the biogeochemical cycle. Then, the major factors that affect the plant litter production and decomposition were identified, which could direct and contribute to future research. The small set of studies reviewed in this paper demonstrated the potential of plant litter to improve the biogeochemical cycle and nutrients in the forest ecosystems. However, further researches are needed particularly on the effect of species, forest structures, seasons, and climate factors on the plant litter production and decomposition in various types of forest ecosystems.

• Journal of Forest and Environmental Science
• /
• v.33 no.4
• /
• pp.281-294
• /
• 2017

Tropical forests constitute almost half of the global forest cover, account for 35% of the global net primary productivity and thereby have potential to contribute substantially to sequester atmospheric $CO_2$ and offset climate change impact. However, deforestation and degradation lead by unsustainable management of tropical forests contribute to the unprecedented species losses and limit ecosystem services including carbon sequestration. Sustainable forest management (SFM) in the tropics may tackle and rectify such deleterious impacts of anthropogenic disturbances and climatic changes. However, the existing dilemma on the definition of SFM and lack of understanding of how tropical forest sustainability can be achieved lead to increasing debate on whether climate change mitigation initiatives would be successful. We reviewed the available literature with a view to clarify the concept of sustainability and provide with a framework towards the sustainability of tropical forests for enhanced carbon stock and climate change mitigation. We argue that along with securing forest tenure and thereby reducing deforestation, application of reduced impact logging (RIL) and appropriate silvicultural system can enhance tropical forest carbon stock and help mitigate climate change.

• Journal of Forest and Environmental Science
• /
• v.32 no.3
• /
• pp.302-310
• /
• 2016

The loss and degradation in tropical forest region are some of the current global concern. Hence, these issues elevated the role of rehabilitated forests in providing ecological products and services. The information on the carbon stock is important in relation to global carbon and biomass use, but lacking from the tropical region. This paper reports the assessment of tree and soil carbon stock in a chronosequence rehabilitated tropical forest stands in Malaysia. The study site was at the UPM-Mitsubishi Forest Rehabilitation Project, UPMKB. $20{\times}20m$ plot was established each and assessed in 2009 at 1-, 10- and 19-year-old sites while an adjacent ${\pm}23-year-old$ natural regenerating secondary forest plot was established for comparison. The overall total carbon stock was in the order of 19-year-old>${\pm}23-year-old$>10-year-old>1-year-old. When forest carbon stock is low, the soil component plays an important role in the carbon storage. The forest carbon recovery is crucial to increase soil carbon stock. The variations in the carbon stock showed the different stages of the forest recovery. Species survived after 19-years of planting are potential species for carbon sequestration activities in rehabilitated forest. Human intervention in rehabilitating degraded forest areas through tree planting initiatives is crucial towards recovering the forest ecological role especially in forest carbon stock capacity.

• Journal of Forest and Environmental Science
• /
• v.30 no.2
• /
• pp.233-242
• /
• 2014

Estimating above-ground biomass is important in establishing an applicable methodology of Measurement, Reporting and Verification (MRV) System for Reducing Emissions from Deforestation and Forest Degradation-Plus (REDD+). We developed an estimation model of diameter at breast height (DBH) from IKONOS-2 image that led to above-ground biomass estimation (AGB). The IKONOS image was preprocessed with dark object subtraction and topographic effect correction prior to watershed segmentation for tree crown delineation. Compared to the field observation, the overall segmentation accuracy was 64%. Crown detection percent had a strong negative correlation to tree density. In addition, satellite-based crown area had the highest correlation with the field measured DBH. We then developed the DBH allometric model that explained 74% of the data variance. In average, the estimated DBH was very similar to the measured DBH as well as for AGB. Overall, this method can potentially be applied to estimate AGB over a relatively large and remote tropical forest in Northern Borneo.

• Journal of Ecology and Environment
• /
• v.38 no.1
• /
• pp.75-84
• /
• 2015

Tropical forests play a critical role in mitigating climate change, and therefore, an accurate and precise estimation of tropical forest carbon (C) is needed. However, there are many uncertainties associated with C stock estimation in a tropical forest, mainly due to its large variations in biomass. Hence, we quantified C stocks in an intact lowland mixed dipterocarp forest (MDF) in Brunei, and investigated variations in biomass and topography. Tree, deadwood, and soil C stocks were estimated by using the allometric equation method, the line intersect method, and the sampling method, respectively. Understory vegetation and litter were also sampled. We then analyzed spatial variations in tree and deadwood biomass in relation to topography. The total C stock was 321.4 Mg C $ha^{-1}$, and living biomass, dead organic matter, and soil C stocks accounted for 67%, 11%, and 23%, respectively, of the total. The results reveal that there was a relatively high C stock, even compared to other tropical forests, and that there was no significant relationship between biomass and topography. Our results provide useful reference data and a greater understanding of biomass variations in lowland MDFs, which could be used for greenhouse gas emission-reduction projects.

• Journal of Forest and Environmental Science
• /
• v.30 no.4
• /
• pp.370-377
• /
• 2014

There are very few studies about soil chemical and biological properties under tropical dry evergreen forest Coromandel Coast, India. The present study was conducted in six tropical dry evergreen forests sites such as Oorani, Puthupet, Vadaagram, Kotthatai, Sendrakillai and Palvathunnan. We measured the quantity of soil chemical, biological properties and selected soil microorganisms for investigating the impacts of soil microbial populations on soil chemical and biological properties. The result showed that total N, P, Ca, S, Fe, Mn, Cu, Co, exchangeable K, Olson P, extractable Ca and phosphobacterial population were higher in the soil from Kothattai forest site. Organic carbon, total Mg, extractable Na, soil respiration, ${\beta}$-glucosidase activity, bacterial population, fungi population and actinomycetes population were higher in the soil from Palvathunn forest site. Total K, $NH_4{^+}$-N, $NO_3{^-}$-N, exchangeable K, extractable Ca, extractable Na, azotobacter population, bacillus population and rhizobacteria population were higher in the soil from Sendrakillai. Beijerinckia population, rhizobacteria and soluble sodium were higher in Puthupet forest soil. Total Si, total Na and exchangeable K were higher in soil from Oorani forest site. Total Mo and exchangeable K were higher in the soil from Vadaagaram forest site. The results showed that organic carbon, total N, $NH_4{^+}$-N, $NO_3{^-}$-N, extractable P, extractable Ca, soil respiration and ${\beta}$-glucosidase were significantly correlated with soil microbial populations. Therefore soil microorganisms are important factor for maintaining soil quality in tropical dry evergreen forest.

• Journal of Forest and Environmental Science
• /
• v.28 no.3
• /
• pp.152-157
• /
• 2012

Sarawak is the largest state in Malaysia that covers 37.5% of the total land area. Multitemporal satellite images of Landsat and SPOT were used to examine deforestation and forest fragmentation in Sarawak between 1990 and 2009. Supervised classification with maximum likelihood classifier was used to classify the land cover types in Sarawak. The overall accuracies of all classifications were more than 80%. Our results showed that forests were reduced at 0.62% annually during the two decades. The peat swamp forest suffered a tremendous loss of almost 50% between 1990 and 2009 especially at coastal divisions due to intensified oil palm plantation development. Fragmentation analysis revealed the loss of about 65% of the core area of intact forest during the change period. The core area of peat swamp forest had almost completely disappeared during the two decades.

• Journal of Forest and Environmental Science
• /
• v.28 no.3
• /
• pp.185-193
• /
• 2012

This study was carried out in Gana Resettlement and Integrated Development (GRID) Project as a pioneer model for Community-Based Forest Management (CBFM) in Sabah, Malaysia. The GRID project is developed to improve community livelihood as well as to promote community involvement in CBFM and at the same time to lessen community encroachment and traditional farming practices inside the forest conservation area. The objectives of this study are: (i) to identify the dependency of local community on forest resources; (ii) to examine local community's roles in conserving forest resources and, (iii) to analyze their views on GRID project in conserving forest. Interviews were conducted with randomly selected 130 households at the GRID project using semi structured questionnaires comprising closed and open-ended questions. The study reveals that community dependency on forest resources have lessened after the resettlement of the GRID project. The community shows positive perspective on their contribution for conserving the forest resources. However, the community's willingness to contribute as well as their real contribution can be further improved. The study recommends the government to create more effective training and relevant activities to improve the livelihood of community as well as to increase their positive perception on forest conservation efforts. Further research to strengthen the relationship between local community and forest governance through forest conservation is also recommended.

• Journal of Forest and Environmental Science
• /
• v.31 no.3
• /
• pp.177-191
• /
• 2015

The effect of environmental variables on the presence and abundance of tree species in a tropical lowland undisturbed limestone and non-limestone forest in Ben En National Park, Vietnam was investigated. The relationships between 13 environmental variables and 29 tree species with a DBH ${\geq}10cm$, as well as between six 6 physical variables with 26 species of seedling and sapling communities were assessed by canonical correspondence analysis (CCA). Data concerning all tree species ${\geq}10cm$ DBH were collected from eighteen $400m^2$ sample plots, while the abundance of regeneration (all individuals ${\leq}5cm$ DBH) was counted in fifty $2{\times}20m$ strip-plots. The significance of species-environments correlations were tested by distribution-free Monte Carlo tests. The CCA of the 29 examined tree species and 13 environmental variables indicated that the presence and abundance of the tree species were closely related to topographic factors. We may confirm that soil properties including pH, soil moisture content, and soil textures, were the most crucial factor in tree species composition and their distribution. Several species including Pometia pinnata, Amesiodendron chinense, Gironniera cuspidate, Cinnamomum mairei, and Caryodaphnopsis tonkinensis were not controlled by soil properties and topographic variables. The CCA also indicated that the abundance of regeneration tree species at all sites had positive and significant correlations with soil depth, while the occurrence of several other tree species (such as Koilodepas longifolium and Aglaia dasyclada) was positively correlated with a higher slope and rocky outcrop.

• Journal of Forest and Environmental Science
• /
• v.28 no.3
• /
• pp.144-151
• /
• 2012

Deforestation is a major and very critical problem faced by many tropical countries including Malaysia. Sabah is the second largest state in Malaysia and its deforestation rate has been accelerating. This study was conducted to monitor the deforestation in Sabah in the last two decades with Landsat images of 1990, 2000 and 2008. Supervised classification with maximum likelihood algorithm was conducted using the Landsat data for monitoring deforestation. In total, between 1990 and 2008, Sabah lost half of its intact forest, or more than 1.85 million ha in less than two decades. Overall, the deforestation rate for all forest types combined for the last two decades was 1.6% per year. Deforestation seemed to be accelerating because the deforestation rate between 1990 and 2000 was 0.9% per year and it had increased to 2.7% per year between 2000 and 2008. The deforestation trend seemed to follow a negative exponential from 1990 to 2008. In contrast, the agricultural areas increased rapidly with a total of increment more than 1 million ha. This confirmed that agriculture especially establishment of commercial plantation was the major factor of deforestation in Sabah for the last two decades.