Genetic diversity and conservation of two threatened dipterocarps(Dipterocarpaceae) in southeast Vietnam

Two threatened dipterocarp species,Dipterocarpus costatus and Dipterocarpus alatus are well-known endangered species in lowland forests of southeastern Vietnam,primarily from habitat loss and over-exploitation of their wood.To develop conservation strategies for these species,we analyzed 242 samples using nine microsatellite markers to determine the genetic variability within and among five populations of D.alatus and three of D.costatus,representing the natural range of dipterocarps in Southeast Vietnam.Results indicated low levels of genetic variability within populations with an average gene diversity of 0.223 for D.alatus and 0.152 for D.costatus.Results of bottleneck tests indicated a reduction in population size of both species(P>0.05).Genetic differentiation among populations was high(FST=0.347 for D.costatus and 0.274 for D.alatus),indicating limited gene flow(Nm=0.662 for D.costatus and 0.47 for D.alatus)and isolated populations related to geographical distances.Analysis of molecular variance showed high genetic variation within populations(72.92%for D.alatus and 60.81%for D.costatus)compared to among populations.Bayesian analysis and UPGMA tree also indicated the two optimal genetic clusters related to geographical distances.These results will provide a platform for the conservation,management and restoration of these species.

Growth performance and scale insect infestation of Shorea leprosula in a common garden experimental plot

Many tree planting programmes have long been initiated to increase forest cover to mitigate the effects of global climate change.Successful planting requires careful planning at the project level,including using suitable species with favourable traits.However,there is a paucity of improvement data for tropical tree species.An experimental common garden of Shorea leprosula was established to study traits related to growth performance which are key factors in planting success.Seedlings of S.leprosula were collected from nine geographical forest reserves.To study the effects of genetic variation,seedlings were planted in a common environment following a randomized complete block design.From performance data collected 2017‒2019,one population showed the highest coefficient for relative height growth,significantly higher than most of the other populations.Interestingly,this population from Beserah also exhibited the lowest coefficient for scale insect infestation.This study provides preliminary results on growth performance and susceptibility to scale insect infestation in S.leprosula and the first common garden experiment site conducted on dipterocarp species.It lays a foundation for future genome-wide studies.

Population Structure and Spatial Pattern of Critically Endangered Dipterocarpaceae Tree Species in Mt. Malindang Range Natural Park, Mindanao, Philippines

Dipterocarps tree species are the key species in most tropical forests because of their economic and ecological value in nature. The present study was carried out to determine the population structure and spatial pattern distribution of critically endangered dipterocarps trees in Mt. Malindang. A total of 638 individuals belonging to 86 species among the 62 genera were recorded at all sites. The highest diversity index was recorded in the elevation range of 700 - 900 masl (3.53). Dipterocarpaceae family had the highest importance value (157.66) among the families recorded in this study. Seven dipterocarp tree species were recorded in this study. Shorea negrosensis Foxw, Shorea polysperma (Blanco) Merr., and Shorea contorta S.Vidal, Shorea squamata (Turcz.) Benth. & Hook.f. ex DC. are listed as critically endangered and Dipterocarpus grandiflorus (Blanco) Blanco as Vulnerable. Soil moisture has a great influence on Anisoptera thurifera (Blanco) Blume, whereas light is positively correlated with Shorea polysperma and negatively correlated with elevation. Diameter-class distribution of critically endangered dipterocarps tree species showed an interrupted growth pattern and because a fewer number of seedlings or saplings were found in each species, this suggested that regeneration is not good. However, threats and disturbances such as illegal poaching, slash and burn, roads, and land conversion to agricultural crops and settlements contribute to the declining population of critically endangered dipterocarps species. Thus, conservation, protection and prioritization management activities in Mt. Malindang are needed.

Forest structure and carbon dynamics of an intact lowland mixed dipterocarp forest in Brunei Darussalam

Tropical forests play a critical role in mitigating climate change because they account for large amount o terrestrial carbon storage and productivity.However,there are many uncertainties associated with the estimation o carbon dynamics.We estimated forest structure and carbon dynamics along a slope（17.3°–42.8°）and to assess the relations between forest structures,carbon dynamics,and slopes in an intact lowland mixed dipterocarp forest,in Kuala Belalong,Brunei Darussalam.Living biomass,basa area,stand density,crown properties,and tree family composition were measured for forest structure.Growth rate,litter production,and litter decomposition rates were also measured for carbon dynamics.The crown form index and the crown position index were used to assess crown properties,which we categorized into five stages,from very poor to perfect.The living biomass,basal area and stand density were 261.5–940.7 Mg ha-1,43.6–63.6 m2ha-1and 6,675–8400 tree ha-1,respectively.The average crown form and position index were 4,which means that the crown are mostly symmetrical and sufficiently exposed for photosynthesis.The mean biomass growth rate,litter production,litter decomposition rate were estimated as11.9,11.6 Mg ha-1a-1,and 7.2 g a-1,respectively.Biomass growth rate was significantly correlated with living biomass,basal area,and crown form.Crown form appeared to strongly influence living biomass,basal area and biomass growth rate in terms of light acquisition.However,basal area,stand density,crown properties,and biomass growth rate did not vary by slope or tree family composition.The results indicate that carbon accumulation by tree growth in an intact lowland mixed dipterocarp forest depends on crown properties.Absence of any effect of tree family composition on carbon accumulation suggests that the main driver of biomass accumulation in old-growth forests of Borneo is not species-specific characteristics of tree species.

Functional trait profiles and diversity of trees regenerating in disturbed tropical forests and agroforests in Indonesia

A main question in restoration of degraded forests and forest landscapes recovering from logging and fire is what to expect from natural regeneration through surviving propagules in the soil or seed sources and associated dispersal agents from the surrounding landscape mosaic,as alternative to tree planting.Tree diversity in secondary forests may be high,but based on newcomer species of low wood density and long-distance,abiotic dispersal modes.We compiled and analyzed three pairs of case studies(totaling 815 plots and 11.8 ha)of secondary forests recovering from logging,fire and conversion to agroforest in Sumatra and Kalimantan(Indonesia)on mineral soils.Data on tree species diversity,wood density frequency distribution(indicative of successional status)and dispersal modes were compared with those of less disturbed comparator forests in the same landscapes.Relatively undisturbed lowland dipterocarp forest in Kalimantan had close to 200 species of trees(>10 cm diameter)at a 1-ha sample scale(and 450 at a 10-ha scale).After repeated fires a sample area of 2 ha was needed to reach the same species richness.Regulation-based logging had little impact on tree species richness.In rubber agroforest with low-intensity management beyond rubber planting,50 tree species were found at a 1-ha scale and close to 100 species in 3 ha.The Kalimantan forest after repeated fires had a markedly higher fraction of lowwood-density trees(40%),but otherwise,all forests sampled were similar in overall wood density profiles.Selectively logged forest managed by a local community(village forest)and rubber agroforest in Sumatra contained larger fractions of heavy-wood-density trees.The majority of trees(50%–70%)had birds,bats and primates as dispersal agents in all sites.Selectively logged forests had higher fractions of autochorous species(15%)compared to other sites.Anemochorous(wind-dispersed)species,especially Macaranga lowii,were most common(20%)in lowland dipterocarp forest.Comparison between secondary forests and agroforests showed the influence of farmer selection regarding what is allowed to grow beyond the pole stage.Wood density and seed dispersal profiles can be used as degradation indicators of species assemblages across various disturbance levels and types,as they reflect the habitat quality of the surrounding landscape mosaics.

Floristic Composition, Structure and Soil Properties of Mixed Deciduous Forest and Deciduous Dipterocarp Forest: Case Study in Madan Watershed, Myanmar

Patterns of woody regeneration in terms of species composition and diversity were studied in mixed deciduous forest (MDF) and deciduous dipterocarp forest (DDF) in Minbyin reserved forest of Lewe Township. A total of 57 plant species of MDF belonging to 28 families and 342 individuals and 25 plant species of DDF consist of 15 families and 285 individuals were identified. Plant species diversity was quantitatively higher in the MDF (H' = 3.68) compared to the DDF (H' = 2.39). Tectona grandis showed the highest density (30), dominance (4.40 m2) and IVI (27.01) of MDF and Dipterocarpus tuberculatus also composed the highest density (109), dominance (9.02 m2) and IVI (81.87) in DDF. The smallest diameter class (10 - 20 cm) comprised with 29 species, 103 individuals in MDF and 18 species, 85 individuals in DDF. The size class distribution displayed a reverse J-shaped pattern. The largest numbers of species were concentrated in the smallest height class in both investigated forests because of height and diameter distribution is closely related. The total densities of seedlings and saplings were 1219 and 531 ha-1 in MDF and 988 and 444 ha-1 in DDF respectively. Although soil texture of (40 - 50 cm) and (90 - 100 cm) were sandy clay loam in mixed deciduous forest, the other layers of both investigated forests were sandy loam.

Diversity of mushrooms in Dry Dipterocarp forest at Phuphan National Park, Sakon Nakhon Province

The purposes of this study were, 1) to study the variety of mushrooms grown in the Dry Dipterocarp forest during the year 2008-2009 by Releve method, 2) to study the relationship between ShoreasiamensisMiq. And Ectomycorrhizal of the Amanitaceae and the Belotaceae families, and 3) study the sequencesof DNAsinsome types of mushrooms in the Amanitaceae and the Balotaceae families by the PCR method. The findings of the study were as thefollowings: First, they were totally 34 types of mush-rooms found in Dry Dipterocarp forest at the Phuphan National Park during the studying period, 2008- 2009. There were 26 types found in both years Amanita hemibapha subsp. javanica Corner & Bas, A. princeps Corner & Bas, A. umbrinolutea (Secr. ex Gillet) Bataille, Termi-tomycesmicro- carpus (Berk. & Br.) R. Heim, T. perforans Heim, T. striatus f. griseus Heim, Boletellusananas (M. A. Curtis) Murrill, B. grisei-purpureus Cor., B. edulis Bull. ex Fr., B. luridus Schaeffer ex Fr., AlpovatrappeiFogel, Can-tharelluscibarius Fries, Craterellusaureus Berk. & Curis, Astraeushygrometricus (Pers.) Morgan, Lactariusaquifluus Peck, L. glaucescens Crossl., L. piperatus (Scop. ex Fr.) S. F. Gray, L. vellereus (Fr.) Fr., L. virescens Fr., R. densifolia (Secr.) Gill, R. emetica (Schaeff. & Fr.) S.F. Gray., R. xelempelina (Schaeff.) Fr., R. foetens (Pers.) Fr., R. rosacea (Pers. ex Secr.) Fries, R. violeipes Quél., R. virescens (Schaeff.) Fries. and those found only in 2009 were Bo-letuscurtisii M. A. Curtis, B. nobilis Peck, RussulaalboareolataHongo, R. cyanoxantha (Schaeff. ex Secr.) Fr. The mushrooms that had been found had significantly relations to the surrounding physical conditions. Second, there was a relationship between the Shoreasiamensis Miq. and Amanita princeps Cor.& Bas., Amanita hemibapha (Berk. & Br.) Sacc. subsp.javanica. Cor. & Bas., Boletus chrysenteron Bull., Boletus griseipurpureus Cor. and Heimiellarestipora (Pat & Bek.) Boedijn. at the intensity of spores 500, 5000, 50000 per each. From the SPSS for ANOVA analysis, the Shoreasiamensis Miq. had no relations to Amanita princeps Cor. & Bas., Amanita hemibapha (Berk. & Br.) Sacc. subsp. javanica. Cor. & Bas., Boletus chrysenteron Bull., Boletus grisei-purpureus Cor. and Heimiellarestipora (Pat & Bek.) Boedijn. in height and circumference growths of Shoreasiamensis Miq. seedlings at the intensity of spores 500, 5000 and 50,000 per each Shoreasiamensis Miq. at 95% level of confidence. Finally, by using the BLASTN computer program toexamine, compare and separate the differences 4 types of mushrooms’ DNA in the Amanitaceae and the Boletaceae families subjected to the PCR method, there were 4 findings i.e. 1342 DNA sbp. of Amanita princeps, 880 DNAs pb. of Boletusnobitis Peck, 1381 DNAs pb. of Boletus edulis Bull. exFr and 758 DNAs bp. of Heimiellaresipora (Pat & Baker).

Improved allometric equations for tree aboveground biomass estimation in tropical dipterocarp forests of Kalimantan,Indonesia

Background： Currently, the common and feasible way to estimate the most accurate forest biomass requires ground measurements and allometric models.Previous studies have been conducted on allometric equations development for estimating tree aboveground biomass（AGB） of tropical dipterocarp forests（TDFs） in Kalimantan（Indonesian Borneo）.However, before the use of existing equations, a validation for the selection of the best allometric equation is required to assess the model bias and precision.This study aims at evaluating the validity of local and pantropical equations; developing new allometric equations for estimating tree AGB in TDFs of Kalimantan; and validating the new equations using independent datasets.Methods： We used 108 tree samples from destructive sampling to develop the allometric equations, with maximum tree diameter of 175 cm and another 109 samples from previous studies for validating our equations.We performed ordinary least squares linear regression to explore the relationship between the AGB and the predictor variables in the natural logarithmic form.Results： This study found that most of the existing local equations tended to be biased and imprecise, with mean relative error and mean absolute relative error more than 0.1 and 0.3, respectively.We developed new allometric equations for tree AGB estimation in the TDFs of Kalimantan.Through a validation using an independent dataset,we found that our equations were reliable in estimating tree AGB in TDF.The pantropical equation, which includes tree diameter, wood density and total height as predictor variables performed only slightly worse than our new models.Conclusions： Our equations improve the precision and reduce the bias of AGB estimates of TDFs.Local models developed from small samples tend to systematically bias.A validation of existing AGB models is essential before the use of the models.