Landscape Agroforestry Modeling for a Sufficiency Economy in Huai Raeng-Klong Peed Watershed, Trat Province, Thailand

This research focused on land use modeling at the landscape scale based on the sufficiency economy philosophy (SE). Using land suitability and pair-wise comparison methods, the study aimed to determine key performance indicators of agroforestry under the SE, to develop a landscape agroforestry model under the SE and to apply the derived model to evaluate the suitability of existing land uses within the study area. The key performance indicators were: the agroforestry indices (AFI)-organic matter, soil erosion, species diversity, income distribution, net present value, resources used, land holding size and acceptance of land use; and the landscape agroforestry indices (LAFI)-soil type, slope, distance to water resource, ability to access to main road, watershed class and conservation area. The AFI and LAFI were weighted based on expert judgment and used in weighted linear combinations to develop the landscape agroforestry model based on an AFI equation and an LAFI equation. The AFI equation was obtained from the land use types based on the SE level, and the LAFI equation was determined from the land suitability level (LS level). The final step showed that most land use types were categorized as being at the highest and high LS levels

SITE INDEX OF SIAMESE ROSEWOOD (Dalbergia cochinchinensis Pierre) IN PLANTATIONS OF THAILAND

Currently, decreased productivity of Siamese rosewood (Dalbergia cochinchinensis Pierre) is a problem due to illegal logging and the guidelines to manage this prevention being may be insufficient. Forest plantations should be promoted to achieve sustainable wood production for this species. Site index (SI) is a measure that can be used to predict forest productivity to identify appropriate sites for planting Siamese rosewood. The objective of the current study was to predict the SI for Siamese rosewood in Thailand. A sample of 78 temporary plots at 26 sites in 16 provinces of Thailand was selected to construct a site index curve with a base age of 30 years. The results showed that the mean age of Siamese rosewood was 28 years (between 13 and 55 years), the mean diameter at breast height (DBH) was 20.03 cm (between 7.99 and 33.80 cm), and the mean dominant height was 20.79 m (between 7.32 and 24.82 m). The SI equation was: SI = e(lnHdo-12.476(A-1-Ab-1)) with an R2 value of 0.406 at p < 0.0001 (chosen as 30 years in the present study). The equation indicated that 14, 18, 22, 26, and 30 m trees belonged to site classes Ι, ΙΙ, ΙΙΙ, ΙV, and V, respectively. Although in natural forest, Siamese rosewood is distributed in dry evergreen and mixed deciduous forests, in the present study, several sites in areas under both in situ and ex situ conservation were in the good and very good site categories. Thus, both areas can be used to plant Siamese rosewood and increase its productivity

Legacy effects of canopy gaps on liana abundance 25 years later in a seasonal tropical evergreen forest in northeastern Thailand

Lianas require host trees to reach and stay in the forest canopy, but as seedlings and juveniles, they benefit from canopy gaps created by treefalls. Here, we evaluated the relative importance of these two aspects, that is, the availability of potential hosts vs. the legacy effect of past treefall gaps, on the local abundance of liana stems in a seasonal tropical evergreen forest in the Sakaerat Biosphere Reserve in northeastern Thailand. Within a 2.5-ha plot for forest dynamics monitoring, canopy height was measured in 1993 and 2018 at 5-m intervals to distinguish areas of mature (canopy height ≥ 20 m), building (10–20 m), and gap phases (< 10 m). In 2017–2018, we surveyed all liana stems ≥ 1 cm in diameter at breast height within 50 subplots (10 m × 10 m each) and recorded their diameter and the diameter of the host tree. Of a total of 445 liana individuals, 242 could be identified at least to the family level, while the others had clear morphological traits of climbing mechanisms. The number of liana stems was higher in areas that had been at the building/gap phase than those at the mature phase in 1993. When this 25-year-old legacy of past gap locations was considered, there was a positive association of local abundance between lianas and trees in areas at the mature phase in 2018. In conclusion, liana abundance reflected a long-term legacy of past treefall gaps more than 25 years earlier in this seasonal evergreen forest

SITE INDICATOR SPECIES FOR PREDICTING THE PRODUCTIVITY OF TEAK PLANTATIONS IN PHRAE PROVINCE, THAILAND

Site quality assessment is critically important in any tree planting activity as it may serve a range of management functions such as, optimizing productivity estimates of forest plantations. This study aimed to evaluate the site quality, using plant indicators species, for three teak plantations located in Northern Thailand belonging to the Forest Industry Organization (FIO). Twenty-four sample plots were chosen to cover all the growth classes within the age range of 6-39 years. The site index of teak was established by using the anamorphic technique which is based on dominant height and age at a base age of 30 years, divided into 3 site index classes as 24, 21, and 18, as good, moderate, and poor site quality, respectively. Associated species, the native species that are tree and shrub habits, were surveyed in the 24 plots and indicator species were classified using the Indicator Species Analysis (ISA) and Two Way Indicator Species Analysis (TWINSPAN). The relationship between indicator species and environmental factors was analyzed by the Generalized Linear Model (GLM). The associated species was classified into 76 species with 21 families. The results of ISA indicated the significant indicator species under the good site class were Streblus ilicifolius, Lagerstroemia floribunda, Dalbergia cana and Lagerstroemia calyculata; while Schleichera oleosa and Dalbergia nigrescens were presented under poor site class, respectively. The results from TWINSPAN supported Streblus ilicifolius, Lagerstroemia floribunda and Schleichera oleosa were obvious indicators.  Each indicator species distribution influenced by various relationships with environmental factors, which soil pH and N were the main factors to distribute all indicator species to 3 relationships. First, the indicator species positively associated with soil pH and negatively associated with N were Streblus ilicifolius and Dalbergia nigrescens. Second, the indicator species positively associated with soil pH and N were Lagerstroemia floribunda and Schileichera oleosa. Third, the indicator species negatively associated with soil pH and positively associated N were Dalbergia cana and Lagerstroemia calyculata. The GLM analysis revealed P, Ca and elevation influenced indicator species distribution. As of writing, this is the first study on species indicators for suitable sites of teak in Thailand. Meanwhile, in the absence of confirmatory studies, these indicators can be used as guide for farmers interested in planting teak. In bare lands, the farmer can apply these indicator species to determine the site quality based on the species’ past appearance

Vertical Structure of Phyllosphere Fungal Communities in a Tropical Forest in Thailand Uncovered by High-Throughput Sequencing.

Phyllosphere fungi harbor a tremendous species diversity and play important ecological roles. However, little is known about their distribution patterns within forest ecosystems. We examined how species diversity and community composition of phyllosphere fungi change along a vertical structure in a tropical forest in Thailand. Fungal communities in 144 leaf samples from 19 vertical layers (1.28-34.4 m above ground) of 73 plant individuals (27 species) were investigated by metabarcoding analysis using Ion Torrent sequencing. In total, 1,524 fungal operational taxonomic units (OTUs) were detected among 890,710 reads obtained from the 144 leaf samples. Taxonomically diverse fungi belonging to as many as 24 orders of Ascomycota and 21 orders of Basidiomycota were detected, most of which inhabited limited parts of the lowest layers closest to the forest floor. Species diversity of phyllosphere fungi was the highest in the lowest layers closest to the forest floor, decreased with increasing height, and lowest in the canopy; 742 and 55 fungal OTUs were detected at the lowest and highest layer, respectively. On the layers close to the forest floor, phyllosphere fungal communities were mainly composed of low frequency OTUs and largely differentiated among plant individuals. Conversely, in the canopy, fungal communities consisted of similar OTUs across plant individuals, and as many as 86.1%-92.7% of the OTUs found in the canopy (≥22 m above ground) were also distributed in the lower layers. Overall, our study showed the variability of phyllosphere fungal communities along the vertical gradient of plant vegetation and environmental conditions, suggesting the significance of biotic and abiotic variation for the species diversity of phyllosphere fungi

Ecological Structure of a Tropical Urban Forest in the Bang Kachao Peninsula, Bangkok

Rapid urbanization has changed the structure and function of natural ecosystems, especially floodplain ecosystems in SE Asia. The ecological structure of vegetation stands and the usefulness of satellite images was investigated to characterize a disturbed tropical urban forest located in the Chao Phraya River lower floodplain, Thailand. Nine sample plots were established on the Bang Kachao Peninsula (BKP) within 4 tropical forest types in an urban area: rehabilitation forest, home-garden agroforestry, mangrove and park. The tree habitats were beach forest, swamp forest, moist evergreen forest, dry evergreen forest, mangrove forest and abandoned orchard or home-garden. Normalized difference vegetation index (NDVI) values obtained from Landsat 7 satellite images were correlated with plant structure from field surveys. NDVI had the highest relationship with stand factors for number of families, number of species, Shannon-Weiner index and total basal area. Linear regression predicted well the correlation between NDVI and stand factors for families and basal area. NDVI trends reflected urban tropical forest typing and biodiversity, being high in rehabilitation and mangrove forests, moderate in home-gardens and low in parks. We suggest that the application of NDVI for assessments can be useful for future planning, monitoring and management of the BKP and hence may contribute for increasing biodiversity and complexity of these urban forests

Species richness of phyllosphere fungal operational taxonomic units (OTUs) in each vertical layer.

<p>(a), (c) The observed and extrapolated number of OTUs was shown for each vertical layer. Complete OTU richness was estimated with three indices: Chao index (red), first- (green) and second-order jackknife index (blue). Gray bar plots indicate the number of host plant individuals. (b), (d) The rarefied number of OTUs at the sample size of 2, 3, and 4. Two datasets were analyzed: (a), (b) a total of 144 samples collected from all 27 plant species and (c), (d) a total of 51 samples collected from a single tree species, <i>Hopea ferrea</i>.</p

Rank–abundance plot for fungal OTUs found in each vertical layer.

<p>For each OTU, the proportion of inhabiting samples out of all samples in the layer (frequency of occurrence) is shown against the rank of the number of inhabiting samples (frequency rank). A total of 144 samples collected from all host plant species were analyzed (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166669#pone.0166669.s005" target="_blank">S2 Fig</a>). Inset pie charts indicate the relative proportion between infrequent (black) and common (white) OTUs. OTUs with a frequency of occurrence of less than 0.5 were defined as infrequent OTUs, and the remaining OTUs were recognized as common OTUs.</p