Dry Deciduous Dipterocarp Forest Research Articles

Multitemporal Landsat Imagery with Optimum Band Ratio Techniques for Deciduous Forest Classification

The objective of the study is to evaluate optimum band ratio combinations data set derived from monthly Landsat 8 imageries for forest type classification around the Sirikit dam reservoir using supervised classification with Maximum Likelihood Classifier (MLC). In this study, imageries data acquired from January 2014 to November 2017 were used to create the monthly band ratio data set of Normalized Difference Vegetation Indices (NDVI), Normalized Difference Moisture Indices (NDMI), and Normalized Burn Ratios (NBR) and used to create the monthly multispectral (MS) data set represented as a case of without applying band ratio techniques. In classifying deciduous forest type, four data sets were used to classify two classes of deciduous forests, namely mixed deciduous forest and dry deciduous dipterocarp forest. After the accuracy assessment, the result showed that the overall accuracy and kappa coefficient of all data sets were between 78.33% – 86.21% and between 44.32% – 62.83%, respectively. Herein, the monthly NDVI multitemporal data set provided the highest overall accuracy and kappa coefficient which were better than the monthly MS multitemporal data set about 4% and 8%, respectively. In conclusion, applying monthly multitemporal data of Landsat 8 with band ratio technique, especially NDVI, can increase the accuracy of deciduous forest type classification.

Assessment of enrichment planting of teak (Tectona grandis) in degraded dry deciduous dipterocarp forest in the Central Highlands, Vietnam

After years of unsustainable logging, dry deciduous dipterocarp forest (DDDF) has become poor in timber stocks and has been converted to industrial crops such as rubber. The objectives of this study were to assess teak (Tectona grandis L.f.) tree establishment under degraded DDDF conditions and to determine factors that influence the suitability of teak as a forest enrichment tree species. A set of 64 experimental plots of 4 900 m2 each was set up and observed for 4–5 years for testing enrichment planting with teak under various combinations of two groups of factors: ecological conditions and forest status. Weighted, non-linear, multivariate regression models were used to detect key factors that influenced the suitability of teak. The results showed that at the age of 4 years the average dominant tree height (defined as 20% of the tallest trees in the experimental plot) reached 11.2, 7.8, 5.3 and 3.8 m for very good, good, average and poor suitability levels, respectively. Survival rates of planted teak from average to very good suitability levels were over 90%. Six key factors that affected the suitability of teak were waterlogging during the rainy season, altitude, stand volume of the degraded DDDF, soil type, percentage of sand and concentration of P2O5 in the soil. Under the extreme ecological and environmental conditions of the DDDF, enrichment planting with teak gave promising results.

Mapping Threatened Dry Deciduous Dipterocarp Forest in South-East Asia for Conservation Management

Habitat loss is the primary reason for species extinction, making habitat conservation a critical strategy for maintaining global biodiversity. Major habitat types, such as lowland tropical evergreen forests or mangrove forests, are already well represented in many conservation priorities, while others are underrepresented. This is particularly true for dry deciduous dipterocarp forests (DDF), a key forest type in Asia that extends from the tropical to the subtropical regions in South-east Asia (SE Asia), where high temperatures and pronounced seasonal precipitation patterns are predominant. DDF are a unique forest ecosystem type harboring a wide range of important and endemic species and need to be adequately represented in global biodiversity conservation strategies. One of the greatest challenges in DDF conservation is the lack of detailed and accurate maps of their distribution due to inaccurate open-canopy seasonal forest mapping methods. Conventional land cover maps therefore tend to perform inadequately with DDF. Our study accurately delineates DDF on a continental scale based on remote sensing approaches by integrating the strong, characteristic seasonality of DDF. We also determine the current conservation status of DDF throughout SE Asia. We chose SE Asia for our research because its remaining DDF are extensive in some areas but are currently degrading and under increasing pressure from significant socio-economic changes throughout the region. Phenological indices, derived from MODIS vegetation index time series, served as input variables for a Random Forest classifier and were used to predict the spatial distribution of DDF. The resulting continuous fields maps of DDF had accuracies ranging from R2 = 0.56 to 0.78. We identified three hotspots in SE Asia with a total area of 156,000 km2, and found Myanmar to have more remaining DDF than the countries in SE Asia. Our approach proved to be a reliable method for mapping DDF and other seasonally influenced ecosystems on continental and regional scales, and is very valuable for conservation management in this region.

Diversity and community composition of ectomycorrhizal fungi in a dry deciduous dipterocarp forest in Thailand

Large forest areas of South-East Asia, are dominated by the Dipterocarpaceae tree family, which contains many important timber species. Unlike many other tropical trees, Dipterocarpaceae rely on ectomycorrhizal (ECM) root symbiosis for their mineral nutrition. This study aims to document the richness and community composition of ECM fungi in a dry deciduous forest in Thailand. Combining morphological and molecular identification methods revealed 69 species of ECM fungi that belong to 17 phylogenetic lineages. The /russula-lactarius, /tomentella-thelephora, /sordariales, /sebacina and /cantharellus lineages were the most species-rich. The fungal richness is comparable to other tropical rain forest sites, but the phylogenetic community structure has elements of both tropical and temperate ecosystems. Unlike tropical rain forests, the Cenococcum geophilum complex was one of the most frequent fungal taxa that had a relatively high ITS genetic diversity over the small sampling area. This study provides the first snapshot insight into the fungal community of dry dipterocarp forests. However, it is necessary to broaden the spatial and temporal scales of sampling to improve our understanding of the below-ground relations of dry and humid tropical forests.

Genetic structure and diversity of Shorea obtusa (Dipterocarpaceae) in Thailand

Abstract Shorea obtusa is a keystone species of the dry deciduous dipterocarp forest in Thailand. In this study, the genetic structure and diversity of this species were evaluated by means of five microsatellite markers. A total of 146 trees were collected from five populations encompassing major forest regions of Thailand. High levels of genetic diversity were found among the five populations with the average He of 0.664. Genetic differentiations between populations, although significant, were low with approximately 3% of genetic variation partitioned among populations. This may indicate that the populations sampled were recently part of a continuous population. A tree constructed using the unweighted pair group method with arithmetic average, based on Nei's genetic distance, divided the populations into three groups. This separation was consistent with the altitudinal zonation of the populations, thus indicating that altitude might play a significant role in the genetic structure of S. obtusa. Areas of high genetic diversity were identified which could be considered priorities for conservation.

Site requirements of the endangered rosewood Dalbergiaoliveri in a tropical deciduous forest in northern Thailand

Planting native trees may complement and accelerate natural regeneration and support recovery of biodiversity in degraded forests. Before planting trees, however, there is a need for species-specific site selection criteria. This study investigates the site requirements of a valuable but endangered rosewood species, Dalbergia oliveri, with the purpose of restoring degraded deciduous forest in northern Thailand. The study was conducted in the Ban Pong Forest near Chiang Mai in northern Thailand. We determined site characteristics of plant communities where D. oliveri occurred with indirect gradient analysis and used the importance value index (IVI) to determine the social position of D. oliveri compared to the dominant tree species. The forest was dominated by fire-tolerant dipterocarps. D. oliveri was a co-dominant component in two communities, mixed deciduous forest and the mesic phase of the deciduous dipterocarp forest, on deeper soils of the foothills and on less sun-exposed slopes. In dry deciduous dipterocarp forest, on the driest or steepest slopes with shallow soil, D. oliveri was an emergent or canopy tree with exceptionally well-developed crowns compared to the much smaller, but numerous dipterocarps. In conclusion, D. oliveri existed across a range of environmental limiting factors within various forest facies of deciduous forest in northern Thailand, and therefore, is likely a suitable candidate for restoration of degraded forests. On highly degraded sites the species can assist in restoring a more mesic forest microclimate. Planting or sowing D. oliveri in degraded forests may help to reduce pressure on the remaining wild rosewood populations, and serves in both conservation of biodiversity and economic production.

Fine root decomposition in tropical dry evergreen and dry deciduous forests in Thailand

Dry evergreen forest (DEF) and dry deciduous dipterocarp forest (DDF) are major forest types extensively distributed in northeastern Thailand, exhibiting different nutrient cycling properties. This study aims to improve our understanding on the pattern of mass loss and nitrogen release from two categories of roots (fine, <2 mm and small, 2–5 mm) of Hopea ferrea at DEF and fine roots of mixed trees and dwarf bamboo (Arundinaria pusilla) at DDF sites. Decomposition experiment was performed for more than 12 months using buried litter bag technique. Initial chemistry was significantly different among the four root litters; fine root of H. ferrea exhibited a low ratios of C:N and acid-insoluble:N. The fine root of dwarf bamboo was characterized by high contents of total carbohydrate and ash. Decomposition rate constants (year−1) of ash-free weight remaining were 1.27 and 0.55 for fine and small roots of H. ferrea, and 0.73 and 0.66 for fine root of mixed trees and dwarf bamboo, respectively. At the end of the experiment, the N concentration in fine and small roots of H. ferrea increased to 1.5 times the initial concentration. Whereas, N mass of dwarf bamboo decreased during the experiment. This suggests a different pattern of root decomposition and N release in two forest ecosystems. Generally, the fine root decomposition was faster in the DEF than in the DDF. The role of initial litter chemistry was more pronounced than the climatic seasonality on the belowground decomposition pattern in our study.

Termite species richness in fire-prone and fire-protected dry deciduous dipterocarp forest in Doi Suthep-Pui National Park, northern Thailand

Fire is prevalent in the dry deciduous forests of south-east Asia, the majority of fires being man-made (Stott 1988). In Thailand, the 10-19% estimated extent of annual burning of dry deciduous dipterocarp forest (1984-1986 data on total estimated area burned each year; Settarak et al. 1987) is thought to be a severe under-estimate (Kanjanavanit 1992). The interaction of fire and termites is poorly known for Asian ecosystems, but African studies show they have complementary roles in the removal of wood and leaf litter (Collins 1981, Trapnell et al. 1976). Termites are the dominant arthropod decomposers in tropical forests (Collins 1983) and savannas (Collins 1981, Holt 1987), and are important mediators of carbon flux (Jones 1990, Lawton et al. 1996). Furthermore, these functions are dependent on the species assemblage structure of the termite community (Lawton et al. 1996). To date, the only study of the effects of fire on termite species richness and abundance is from Australia (Abensperg-Traun & Milewski 1995). Here, a preliminary survey of species richness of termites in fireprotected and fire-prone deciduous forest in northern Thailand is presented. The study suggests that the fungus-growing Macrotermitinae have a greater species richness, under certain seasonal fire regimes, compared to those in areas under complete fire protection. Species richness estimates were made for two dry deciduous dipterocarp forest sites: A, fire-protected and; B, unprotected, fire-prone, in Doi Suthep-Pui National Park, near Chiang Mai, northern Thailand. Site A covered a 10 ha

Behaviour and movements of sympatric civet species in Huai Kha Khaeng Wildlife Sanctuary, Thailand

Five individuals of four civet species were captured and followed by radiotelemetry in a mosaic of dry tropical forest in Huai Kha Khaeng Wildlife Sanctuary, Thailand. Observations were made on a fifth, arboreal species which was never captured. Radio‐collared civets used overall areas ranging from 3.1 to 17 km2 with average monthly ranges from 0.72 to 5.4 km2. Average monthly ranges, home range centre shifts and activity radii showed a linear increase with weight and size of the individual, both within and between species. Despite individual differences, there were similar behavioural responses to extrinsic seasonal changes. Civets had activity levels of 50–55% and displayed nocturnal activity patterns. The four smallest civets used trees as resting sites extensively while the largest civet, Viuerra zibetha, was always located on the ground. Faecal analysis indicated that civets fed on at least 18 fruiting tree species as well as rodents, insects and crabs. At least one of the fruits found in civet faeces, Cassia fistula, was not eaten by other major frugivores in the area. The civets showed a preference for mixed deciduous and dry evergreen forest over dry deciduous dipterocarp forest, which had a lower abundance of known food items. The role that civets play as seed dispersal agents may help in the maintenance and structuring of tropical forest communities.

Notes on the Behavior and Movements of Leopard Cats, Felis bengalensis, in a Dry Tropical Forest Mosaic in Thailand

Three males and one female leopard cat were radio-collared and followed for periods of 1-13 months in Huai Kha Khaeng Wildlife Sanctuary, Thailand. The cats had overall home ranges from 1.5-7.5 km2 with core areas of 0.72 km2. A female leopard cat utilized an area of 6.6 km2 over 13 months while a male leopard cat, who shifted ranges, used 7.5 km2 over 3.5 months. Cats followed for longer periods of time generally showed larger overall ranges. The cats were active 50 percent of the time and displayed arrhythmic activity patterns. Leopard cats followed for at least several months showed seasonal variation in movement and ranging patterns. Fourteen prey items were identified in the feces of leopard cats, with small mammals, particularly Maxomys surifer, dominating the prey. Leopard cats preferred resting and moving on the ground, utilizing dry deciduous dipterocarp forest proportionally less than dry evergreen or mixed deciduous forest. Annual fires that help maintain the dry deciduous dipterocarp forest in the study area may affect both short and long term survival of leopard cats.

The Spatial Pattern of Dry Season Fires in the Savanna Forests of Thailand

This paper reports the first stage of a research project to investigate the vertical and horizontal spatial pattern of temperatures in the fires which are common throughout the dry deciduous dipterocarp forests of north and northeast Thailand from December to March every year. The work was carried out by using 'Thermocolor' mica pyrometers in experimental burns at three localities. The construction, calibration, field deployment and limitations of the pyrometers are fully described. It is shown that there are two basic types of vertical temperature profile, for which characteristic curves are provided. These occur in different forms in four main types of burn, namely: (1) typical litter burns; (2) extreme litter burns; (3) typical groundcover burns; (4) extreme groundcover burns. The fire characteristics of each are described in detail. Extreme groundcover burns may attain temperatures of between 700 and 900?C at 0.5-1 m above the ground and spread at rates exceeding 3.0 cm/s even in near windless conditions. Unfortunately, a policy of fire exclusion leads to the groundcover associations that give rise to this dangerous type of wildfire and a policy of prescribed burning is preferable. The insulating properties of both the sandy loam soils and the bark of savanna forest tree species are demonstrated and it is concluded that the dry deciduous dipterocarp forest ecosystem is well adapted to fire. Suggestions for further