Forest In Thailand Research Articles

Contrasting seasonal leaf habits of canopy trees between tropical dry-deciduous and evergreen forests in Thailand

We compared differences in leaf properties, leaf gas exchange and photochemical properties between drought-deciduous and evergreen trees in tropical dry forests, where soil nutrients differed but rainfall was similar. Three canopy trees (Shorea siamensis Miq., Xylia xylocarpa (Roxb.) W. Theob. and Vitex peduncularis Wall. ex Schauer) in a drought-deciduous forest and a canopy tree (Hopea ferrea Lanessan) in an evergreen forest were selected. Soil nutrient availability is lower in the evergreen forest than in the deciduous forest. Compared with the evergreen tree, the deciduous trees had shorter leaf life spans, lower leaf masses per area, higher leaf mass-based nitrogen (N) contents, higher leaf mass-based photosynthetic rates (mass-based P(n)), higher leaf N-based P(n), higher daily maximum stomatal conductance (g(s)) and wider conduits in wood xylem. Mass-based P(n) decreased from the wet to the dry season for all species. Following onset of the dry season, daily maximum g(s) and sensitivity of g(s) to leaf-to-air vapor pressure deficit remained relatively unchanged in the deciduous trees, whereas both properties decreased in the evergreen tree during the dry season. Photochemical capacity and non-photochemical quenching (NPQ) of photosystem II (PSII) also remained relatively unchanged in the deciduous trees even after the onset of the dry season. In contrast, photochemical capacity decreased and NPQ increased in the evergreen tree during the dry season, indicating that the leaves coped with prolonged drought by down-regulating PSII. Thus, the drought-avoidant deciduous species were characterized by high N allocation for leaf carbon assimilation, high water use and photoinhibition avoidance, whereas the drought-tolerant evergreen was characterized by low N allocation for leaf carbon assimilation, conservative water use and photoinhibition tolerance.

Density estimates of nine hornbill species in a lowland forest site in southern Thailand

Hornbills are useful indicators of forest condition and human disturbance because they require large tracts of unfragmented forest with large fruiting trees for feeding and nesting. They are relatively large-bodied, which makes them targets for hunting. Density estimates of such species are critical for population monitoring and serve as a baseline against which future changes can be measured. In this study we used variable-width line transect surveys to estimate the densities of nine hornbill species in the Bala portion of the Hala-Bala Wildlife Sanctuary on the Thai–Malaysia border, one of the few remaining areas of lowland forest in Thailand. The hornbill species were: Rhinoceros (Buceros rhinoceros), Great (B. bicornis), Helmeted (B. vigil), Black (Anthracoceros malayanus), Bushy-crested (Anorrhinus galeritus), White-crowned (Aceros comatus), Wrinkled (A. corrugatus), Wreathed (A. undulatus) and Plain-pouched (A. subruficollis). Between January 2001 and April 2002, 11 transects along trails, old logging roads and one paved road were surveyed once per month. A total of 1,261 observations of the nine species were made during the observation period. Estimates for Rhinoceros and Helmeted Hornbill were 2.69 and 1.21 individuals/km2, respectively, and were similar or slightly higher than densities reported elsewhere. Estimates for Great (0.12), Bushy-crested (0.64), Wrinkled (0.08), White-crowned (0.08) and Wreathed Hornbills (0.69) were generally lower than estimates from other areas in the region. It was not possible to obtain density estimates using distance sampling for Black and Plain-pouched Hornbills due to the small number of observations, but our data did suggest that their densities were also low (<0.10 individuals/km2). Potential reasons for differences between this and other areas include a scarcity of lowland habitat, habitat isolation, lower abundance of specific fruit resources and interspecific competition, but these factors require further investigation. Standardization of survey techniques among studies would significantly improve assessments of habitat requirements as well as of the effects of human disturbance on Asian hornbills, most of which are globally threatened. Our study specifically underscores the need for additional research on the Plain-pouched Hornbill, the most threatened of the species studied, as density estimates from elsewhere in its range are lacking, while more generally it highlights the need to investigate the underlying causes of the often substantial variation in hornbill densities among species and sites.

Dispersal of Canarium euphyllum (Burseraceae), a large-seeded tree species, in a moist evergreen forest in Thailand

We investigated the dispersal of a large-seeded tree species, Canarium euphyllum (Burseraceae), in the moist evergreen forests of the Khao Yai National Park in Thailand. By combining direct observations of fruit consumption in tree canopies (543 h) and the camera-trapping observations of fallen fruit consumption on the forest floor (175 camera-days), we identified the frugivore assemblage that foraged on the fruits of C. euphyllum and assessed their role in seed dispersal and seed predation. In the canopy, our results showed that seeds were dispersed by a limited set of frugivores, one pigeon and four hornbill species, and predated by two species of squirrel. On the forest floor, seven mammal species consumed fallen fruits. A combination of high rates of fruit removal and short visiting times of mountain imperial pigeons (Ducula badia) and hornbills (Buceros bicornis, Aceros undulatus, Anorrhinus austeni and Anthracoceros albirostris) led us to conclude that these large frugivorous birds provide effective seed dispersal for this tree species, in terms of quantity. These frugivorous species often have low tolerance to negative human impacts and loss of these dispersers would have severe deleterious consequences for the successful regeneration of C. euphyllum.

Farmers in Degraded Forest in Thailand : Their Behavior and Socio-economic Conditions

Farmers in Degraded Forest in Thailand : Their Behavior and Socio-economic Conditions

Characteristics of hornbill-dispersed fruits in a tropical seasonal forest in Thailand

Asian hornbills are primarily frugivorous. We studied the characteristics of fruits consumed by four sympatric hornbill species in Thailand: Great Hornbill (Buceros bicornis), Wreathed Hornbill (Aceros undulatus), Austin's Brown Hornbill (Anorrhinus austeni) and Oriental Pied Hornbill (Anthracoceros albirostris). We compared the frequency of distribution of 11 variables for all fruit species collected in the study area (n = 259) and fruit species consumed by hornbills (n = 73). Our analysis revealed that fruits consumed by hornbills are: (1) large, (2) easily accessible within the canopy, (3) red, purple or black and (4) dehiscent or indehiscent with a thin husk. The range of fruit sizes eaten by hornbills in our study is comparable to that reported from other sites in Southeast Asia and Africa. The large gape width of hornbills enables them to consume large fruits that small frugivores would find difficult to consume.

Pattern and impact of hornbill seed dispersal at nest trees in a moist evergreen forest in Thailand

Following the entire process of frugivore seed dispersal, from intake of seeds to seed deposition, is a difficult task. One alternative is to monitor areas of heavy seed rain deposited by animals. We quantified the number of seeds deposited by hornbills and followed the fates of these seedlings for 3 y to evaluate the effectiveness of hornbill seed dispersal at nest trees, on the basis of seedling survival. For 14 mo, fallen fruits and seeds were collected in traps established around four nest trees of each of two hornbill species (Aceros undulatus and Anthracoceros albirostris) and the seedlings were monitored in adjacent quadrats. Seedfall and seedlings of species represented in hornbill diets occurred at significantly higher densities in the traps/quadrats in front of nest cavities than in other traps/quadrats. Fewer seedling species and individuals germinated under nest trees than expected from the composition of the seedfall. Our results suggest that the quality of hornbill seed dispersal might be poor at nest trees due to the highly concentrated seedfall, which results in high seed and seedling mortality. Although seed deposition at nest trees is a useful guide to hornbill diet during the breeding season, it is clearly not of benefit to the plants involved. However, the pattern and consequences of hornbill seed dispersal at nest sites is likely very different from that during the non-breeding season.

Alien Abduction: Disruption of Native Plant‐Pollinator Interactions by Invasive Species

ABSTRACTThe indirect impacts of Shorea siamensis‐logging on the reproductive ecology of Dipterocarpus obtusifolius, a self‐incompatible butterfly‐, moth‐, and bird‐pollinated tree, were studied in tropical dry forest in Thailand. Pollinator activity at D. obtusifolius trees and subsequent seed production were recorded in three forest areas subject to differing intensities of S. siamensis extraction. The pollinator and plant understory communities in these areas were also noted. Forest areas subject to high S. siamensis extraction intensities had very high understory flowering plant cover, dominated by the exotic invader Chromolaena odorata. Activity of butterfly pollinators at D. obtusifolius trees decreased in these disturbed areas, although their abundance remained comparable to other forest areas subject to only moderate or no extraction. For sphingid moth pollinators, there was no difference across differentially disturbed forest areas in either abundance or in the proportion bearing pollen. Pollinator activity by birds increased at highly disturbed locations but was not sufficient to offset a decline in overall pollinator activity at D. obtusifolius canopies in areas of heavy 5. siamensis extraction. Thus, extraction of S. siamensis indirectly affected the pollination of D. obtusifolius, primarily by causing changes in the foraging behavior of butterfly pollinators rather than their abundance. A shift in the relative abundance of floral nectar resources from the canopy to the understory, a consequence of 5. siamensis extraction and invasion by C. odorata, led to a parallel shift in foraging location of the principal diurnal pollinators, the butterflies, toward the understory. Despite reduced pollination at disturbed sites, behavioral changes did not translate into a D. obtusifolius seed set effect, possibly because pollination by birds (or moths) at the disturbed site compensated for reduced butterfly pollination.

Research needs for restoring seasonal tropical forests in Thailand: accelerated natural regeneration

Accelerated natural regeneration (ANR) is a relatively cheap method of reforestation, which encourages natural establishment of indigenous trees and shrubs. It requires a low input of labour, but a high input of ecological information. In this paper, the knowledge required to predict and manipulate the natural regeneration of seasonal tropical forest is reviewed and areas in need of further research are identified. Regeneration will be influenced by five groups of potentially limiting factors; site resources (soil and microclimate); competition with weeds; site disturbance; occurrence of established woody plants or their propagules; seed dispersal by wild animals and birds. This paper considers each of these, their interactions with seasons, and each other. Collation of existing information on these topics, combined with the suggested further research, should facilitate the creation of tools that will enable practitioners to judge the regeneration potential of sites and to select the most appropriate ANR techniques.

Estimation of buffering capacity of mangrove soils by using hydrophobic organic compounds, atrazine and linuron

Samples of two soils and two sediments collected at sites originating from mangrove forests in Thailand, were examined in terms of buffering capacity to organic compounds. Atrazine and linuron were used as representative hydrophobic organic compounds for estimating the buffering capacity by observing their adsorptive and desorptive behavior. The buffering capacity could be represented by the distribution of the adsorption ratio (AR) and desorption ratio (DR) as follows: AR (%) = (amount of herbicide adsorbed per unit weight of soil)/(initial amount of herbicide) x 100, and DR (%) = (amount of herbicide desorbed per unit weight of soil after herbicide desorption experiments) / (initial amount of adsorbed herbicide on soil) x 100. The soil under mangrove forests displayed a larger buffering capacity to atrazine and linuron. Compared with 42 soils from Japan, in terms of the adsorption proparty of atrazine and linuron, the mangrove soil ranked in a higher category on the classification of the Japanese soils. Thus, the importance of maintaining or recovering the mangrove forests to promote environmental conservation was emphasized.

Two new genera of Zodariidae (Araneae) from Southeast Asia

Two new genera of Zodariidae, belonging to the Zodariinae and strongly related to Mallinella Strand, are reported from evergreen forests in Thailand and Malaysia. Euryeidon gen. n. is represented by six species, all of which are new: E. monticola sp. n. (the type species; ♂♀), E. musicum sp. n. (♂♀), E. anthonyi sp. n. (♂♀), E. sonthichaiae sp. n. (♂), E. consideratum sp. n. (♀) and E. schwendingeri sp. n. (♀). The genus is characterized by its strongly reticulate carapace and widely spaced eyes. Heradion gen. n. is represented by five new species, all known from both sexes, which can be clustered in two species groups on the base of somatic characters. The first group, found in Thailand, consists of Heradion naiadis sp. n. (the type species) and H. peteri sp. n. The second group is restricted to Malaysia and consists of three smaller, long-legged species: H. pernix sp. n., H. damrongi sp. n. and H. luctator sp. n. Heradion is characterized by: carapace smooth, domed; chilum drawn out into a point, pointing forward; sternum with anterior concavity accommodating labium; sclerotized field in front of the spinnerets with rows of hairs; femora inflated dorsally near proximal dorsal spine; coxae I and IV elongated. Keys to the genera of Zodariinae in Southeast Asia and to the species of Euryeidon and Heradion are provided.

Alien Abduction: Disruption of Native Plant-Pollinator Interactions by Invasive Species1

ABSTRACT The indirect impacts of Shorea siamensis-logging on the reproductive ecology of Dipterocarpus obtusifolius, a self- incompatible butterfly-, moth-, and bird-pollinated tree, were studied in tropical dry forest in Thailand. Pollinator activity at D. obtusifolius trees and subsequent seed production were recorded in three forest areas subject to differing intensities of S. siamensis extraction. The pollinator and plant understory communities in these areas were also noted. Forest areas subject to high S. siamensis extraction intensities had very high understory flowering plant cover, dominated by the exotic invader Chromolaena odorata. Activity of butterfly pollinators at D. obtusifolius trees decreased in these disturbed areas, although their abundance remained comparable to other forest areas subject to only moderate or no extraction. For sphingid moth pollinators, there was no difference across differentially disturbed forest areas in either abundance or in the proportion bearing pollen. Pollina...

Micromonospora aurantionigra sp. nov., Isolated from a Peat Swamp Forest in Thailand

Actinomycete strain TT1-11T, which produces single non-motile spores on substrate hyphae, was isolated from peat swamp forest soil in Thailand. The isolate showed morphological and chemotaxonomic properties consistent with its classification in the genus Micromonospora. Phylogenetic analysis using 16S rDNA sequences supported this assignment and it formed a subclade with M. coerulea. This isolate can be distinguished from M. coerulea by its physiological and biochemical properties, and it showed a less than 53% DNA relatedness to the type strains of all the validly named Micromonospora species. On the basis of phenotypic, genotypic and phylogenetic data, strain TT1-11T (=JCM 12357T =PCU 239T =DSM 44815T=TISTR 1232T) is proposed as the type strain of a novel Micromonospora species, Micromonospora aurantionigra sp. nov.

Survival and germination of an experimental seed bank population of two species of Lauraceae in a tropical montane forest in Thailand

The survival and germination traits of two tropical species of Lauraceae, Lindera metcalfiana and Litsea cubeba, were investigated in a 2-year burial experiment and subsequent germination tests of sequentially excavated seeds. Fresh seeds extracted from fruit were packed in aluminum mesh bags and buried 5cm deep in a mature montane forest in northern Thailand (1700m altitude). No seed mortality was recorded for Litsea, but Lindera experienced 26%–48% mortality after being buried for 122 days. These seeds did not germinate in the forest soil during the 2-year experimental period. We found that fresh seeds of these two species did not germinate even under open conditions, suggesting that the seeds are initially deeply dormant after dispersal. In contrast, 29%–60% of excavated Lindera seeds germinated under open conditions after being buried for 30–753 days, and excavated Litsea seeds began to germinate after being buried for 408 days. These findings suggest that seeds enter a state of enforced dormancy. The ratio of germinable seeds peaked 184 days after burial in Lindera (33%) and 930 days after burial in Litsea (91%). The longer period of deep dormancy in Litsea prior to enforced dormancy is concordant with the fact that for regeneration Litsea requires larger-scale disturbance than Lindera.

Fire history influences on the spatial heterogeneity of soil nitrogen transformations in three adjacent stands in a dry tropical forest in Thailand

Spatial patterns of soil nitrogen (N) transformations were examined using geostatistical analysis in three adjacent stands with different fire history (0, 10 and 35 years since the latest fire, respectively) in a dry tropical forest in Thailand. A larger pool of total inorganic N and a faster rate of N mineralization were recorded in the stand with longer fire prevention. At the spatial scale analyzed, the proportion of spatially dependent variance to the total variance of N mineralization and nitrification increased from 0.39 to 0.73, and from 0.40 to 0.77, respectively, with the time since the latest fire. The spatial autocorrelation ranges of N mineralization and nitrification decreased from ≥9.0 to 3.28 m, and ≥9.0 to 2.77 m, respectively, with the time since the latest fire. These results suggested that fire history affected not only the level of available soil N, but also the spatial heterogeneity of soil N transformations, presumably due to the difference in plant influences on soil.

Interactions between fleshy fruits and frugivores in a tropical seasonal forest in Thailand.

Large frugivores are considered to be important seed dispersers for many tropical plant species. Their roles as seed dispersers are not well known in Southeast Asia, where degraded landscapes typically lack these animals. Interactions between 259 (65 families) vertebrate-dispersed fruits and frugivorous animals (including 7 species of bulbul, 1 species of pigeon, 4 species of hornbill, 2 species of squirrel, 3 species of civet, 2 species of gibbon, 1 species of macaque, 2 species of bear, 2 species of deer, and 1 species of elephant) were studied for 3years in a tropical seasonal forest in Khao Yai National Park, Thailand. The purpose was to examine the dietary overlaps among the large frugivores and the characteristics of fruits they consumed. Most fruit species are eaten by various kinds of frugivores; no close relationship between a particular fruit and a frugivore was found. The number of frugivore groups that served a given plant species was negatively correlated with seed size. Additionally, the fruit/seed diameters consumed by bulbuls were significantly smaller than consumed by the other nine groups. These trends of fruit characteristics were consistent with those observed elsewhere in Southeast Asia: small fruits and large, soft fruits with many small seeds are consumed by a wide spectrum of frugivores while larger fruits with a single large seed are consumed by relatively few potential dispersers. Importantly, these large, single-seed fruits are not consumed by the small frugivores that thrive in small forest fragments and degraded areas in Southeast Asia. To insure the natural seed dispersal process in the forest, an evaluation of all frugivore groups in the forest is urgently needed in Southeast Asia.

Termite ecology in a dry evergreen forest in Thailand in terms of stable (δ13C and δ15N) and radio (14C, 137Cs and 210Pb) isotopes

Stable (δ13C and δ15N) and radio‐ (14C, 137Cs and 210Pb) isotopes were determined for termites that have been sampled from a dry evergreen forest in Thailand. A wood‐feeding termite, Microcerotermes crassus, was separated from soil‐feeders: Termes propinquus, Termes comis and Dicuspiditermes makhamensis by δ13C and δ15N values. The Termes group in Thailand had less diverse values in δ13C and δ15N than those in Australia, where the feeding habits of the ‘Termes’ group are more diverse. Other soil‐feeding termites produced similar δ13C values, but a larger range in δ15N values. 14C‐percent modern carbon (pMC) values suggest that the soil‐feeding termites used younger carbon than the wood‐feeding termites, and this was consistent with the termites from Cameroon, central Africa. Values of δ13C and 14C‐pMC indicate that surface soil was used by a soil‐feeding termite, D. makhamensis, in making the nest mounds, and deeper soil (10–30 cm) by a fungus‐growing termite, Macrotermes carbonarius. 210Pb and 137Cs were scarcely incorporated into the termites, although 214Pb was recovered from the workers. The results suggest that stable‐ and radioisotopes are useful in the study of detritivorous animals, organic matter decomposition and ecosystem engineering.

Kockovaella barringtoniae sp. nov., a new basidiomycetous yeast species isolated from a plant leaf collected in a tropical rain forest in Thailand.

One yeast strain characterized by the proliferation of non-ballistosporous stalked conidia, budding cells and ballistoconidia, the presence of xylose in whole-cell hydrolysates, the presence of Q-10 as the major ubiquinone isoprenologue, the inability to ferment sugars and positive diazonium blue B (DBB) and urease reactions was isolated from a plant sample collected in a tropical rain forest in Thailand. The isolate clustered with Kockovaella species in the 18S rDNA-based tree. On the basis of the morphological, biochemical and molecular phylogenetic characteristics, the isolate was assigned to the genus Kockovaella. DNA complementarity experiments showed that the isolate was genetically distinct from known species of the genus Kockovaella. The isolate is described as Kockovaella barringtoniae sp. nov. The type strain is strain TY-278T (= JCM 10998T = TISTR 5770T).

The effects of drought and fire on seed and seedling dynamics in a tropical seasonal forest in Thailand

Seed production and seedling dynamics were studied for 6 years(1992–1997) with particular emphasis on the effects of the drought andfire in a natural tropical seasonal forest at Mae Klong Watershed ResearchStation, Kantchanaburi, western Thailand. The number of seed produced andemerged seedlings varied greatly among years and species. Most tree speciesproduced very few seeds in 1994 and many in 1995 and 1996, particularly,Shorea siamensis Miq. which displayed the most seedinghabit. Some seedlings, Shorea, Dipterocarpus alatus Roxb.,and Dipterocarpus turbinatus Gaertn. f., emerged at theendof the dry season (late April, after the first rain but when soils still have alow soil moisture content), while the majority of seedlings emerged at thebeginning of the rainy season. After a fire disturbed the plot in April 1996,many species increased their seedling emergences, especially Berryaammonilla. Seedlings of most species less than a year old showed arelatively low mortality in the rainy season, but those ofPterocarpusmacrocarpus Kurz had high mortality. The mean survival rate for allseedling species in this forest was quite low (24.1% y−1), anddifferent values existed for the rainy and the dry season (11.5, and 6.1%month−1, respectively). This suggests that different specieshave adaptations related to the season of seedling emergence and resistance todrought in this tropical seasonal forest community. The traits of tree speciesare classified in terms of their traits in the early stages of regeneration;seed and/or seedling bank, resprouting, and drought resistance. Most specieshave adapted to fire and/or drought by resprouting, seed bank, and/or seedlingbank, although the few species which occur mainly in mesic evergreen forestshave less adapted to these environments. The demographic variations in seed andseedling stages may contribute to the coexistence of these species in thisspecies-rich dry tropical forest.

Research needs for restoring tropical forests in Southeast Asia for wildlife conservation: framework species selection and seed propagation

Some governments in Southeast Asia, such as those of Thailand and Vietnam have clear policies to restore large areas of degraded land to native forest. However, knowledge needed for the success of these ambitious programmes is still inadequate, and considerable further research is required. Furthermore, very little literature is available to conservation practitioners about the restoration of tropical forests for biodiversity conservation. This paper introduces the framework species method of forest restoration, which is being developed to restore forests in Thailand. The paper examines the potential for adoption of this technique in different forest types across the Southeast Asia region, and identifies priorities for future research needed before the method can be widely implemented. These include the identification of forest types, the selection of candidate framework species, maintenance of genetic diversity, and development of methods of seed collection and germination.

Impact of logging on the richness and diversity of forest butterflies in a tropical dry forest in Thailand

Studies on the impact of logging on tropical forest butterflies have been almost exclusively conducted in moist forest habitats. This study considers the impacts of small-scale logging on butterfly communities at three sites of varying disturbance intensity in a tropical dry forest in western Thailand. Butterfly species richness was similar at all sites, but the abundance of butterflies and diversity of the butterfly community decreased with increased logging disturbance. The recorded decrease in diversity at the relatively large sampling scale used lends further support to the hypothesis that disturbance effects are scale dependent. Species abundance data for butterflies fitted a log-normal distribution at all sites, but also a log-series distribution at the two disturbed sites. These analyses suggest a more complex butterfly community at the undisturbed site, but also that log-series and log-normal distributions may not to be sufficiently sensitive to be useful indicators of community changes following logging. Community ordination separates both the butterfly species and transect samples into three distinct regions corresponding to the three study locations. Ordination axes are correlated with tree density, understorey cover and understorey plant richness. Species with the smallest geographic ranges tend to be the least abundant and occurred most frequently in the undisturbed site. The observed diverging responses to disturbance among butterfly families diminishes the value of butterfly communities as biodiversity indicators, and forest managers should perhaps focus on restricted range species or of groups of recognized sensitive species for this purpose.