Growth assessment of upper hill dipterocarp (Shorea platyclados) at the various slope in a rehabilitated landscape

Rehabilitation aims to improve landscape function while increasing its resilience to climate change. Gunung Dahu research forest is a rehabilitated hilly landscape that is planted with more than 25 dipterocarp species, including an upper hill dipterocarp tree of Shorea platyclados at various site conditions. This study aimed to assess the growth performance of S. platyclados at five sloping levels class of 0-8%, 8-15%, 15-25%, 25-45%, and >45%. Observed growth attributes were stem diameter, total height, basal area, Mean Annual Increment (MAI), and Leaf Area Index (LAI), and diameter. The results showed that sloping levels significantly affect the growth performance of the planted trees. The highest slope level (>45%) supported the highest average stem diameter and tree height (41.48 cm and 20.86 m). The sloping level of >45%, 25-45%, 15-25%, 8-15%, and 0-8% yield different value of average diameter which were 41.48 cm, 35.86 cm, 36.54 cm, 34.61 cm, and 31.23, while the average height were 20, 86m, 19.78 m, 16.72 m, 18.84 m, 18.61 m respectively. Thus, the upper hill dipterocarp of S. platyclados is a prospective native tree species for rehabilitating hilly upland landscapes.

The growth performance of dipterocarps species and understorey diversity in the Gunung Dahu Research Forest, Leuwiliang, Bogor

Dipterocarps species is the main species composes Gunung Dahu research forest. Habitat suitability and growth performance of a species are some factors considered in the species selection for forest establishment. The understorey in a forest community serves to protect soil from erosion. This research aimed is to analyze the growth performance of various Dipterocarpaceae species and study understorey diversity in the research area. The measurement was conducted in four species trial plots contain ten Dipterocarps species consist of five individuals per species per plot or 200 individuals in total. The growth performance of Dipterocarp species was analyzed using the current annual increment (CAI) and mean annual increment (MAI) methods. The understorey diversity was analyzed using the Shannon-Wiener Index. The result showed that Shorea johorensis obtained the highest CAI, 0.95 cm year−1, and Shorea platyclados got the highest MAI, 1.78 cm/year. S. platyclados and S. leprosula were projected to reach <40 cm in diameter after they got 25 years. The Gunung Dahu research forest’s understorey was classified as moderate (1.68 - 2.33). The dominant understorey species, namely Oldenlandia auricularia, Neprolephis biserrate, Ottochloa nodosa, and Gleichenia linearis. This study concluded that the growth performance of Dipterocarps species in the study area varied, and the understorey condition was classified as moderate, where its diversity has a positive correlation with the crown openness.

Tree Communities and Aboveground Biomass in the Submontane Zone of Ketambe Resort, Mount Leuser National Park, Aceh

Mount Leuser National Park is one of the largest conservation areas and plays important ecological and economic functions. To support forest management, it is important to gain current vegetation data. The sampling method of a 0.1 hectare plot was carried out on two sampling sites in the submontane zone of Ketambe Resort, Mount Leuser National Park, Aceh. The diversity of trees was not significantly different, while species composition was different. Site one was dominated by Syzygium spp. and Shorea platyclados, while site two was dominated by Altingia excelsa and Bridelia glauca. Lauraceae, Myrtaceae, and Dipterocarpace families dominated in both sites. Tree structures formed three strata and showed a good capacity for forest regeneration. The aboveground biomass of site one was higher than site two due to the presence of more large trees. Pioneer species, cultivated plants, a low average wood density, and low aboveground biomass indicated secondary forest characteristics in both sites. Abstrak: Taman Nasional Gunung Leuser merupakan salah satu kawasan konservasi yang terluas dan memiliki fungsi ekologi dan ekonomi yang penting. Data vegetasi terkini penting didapatkan untuk mendukung pengelolaan hutan. Metode sampling dengan plot 0.1 hektar dilakukan di dua lokasi pada zona submontana Resort Ketambe, Taman Nasional Gunung Leuser, Aceh. Keanekaragaman jenis pohon tidak berbeda secara nyata sementara komposisi jenis berbeda. Lokasi satu didominasi oleh Syzygium spp. dan Shorea platyclados, sementara lokasi dua didominasi oleh Altingia excelsa dan Bridelia glauca. Suku Lauraceae, Myrtaceae dan Dipterocarpace mendominasi pada kedua lokasi. Struktur pohon membentuk tiga strata dan menunjukkan kemampuan regenerasi hutan yang baik. Biomassa pohon di atas permukaan pada lokasi satu lebih tinggi dibandingkan lokasi dua karena lebih banyaknya pohon berukuran besar. Jenis pionir, tanaman budidaya, rata-rata berat jenis kayu dan biomassa di atas permukaan yang rendah mengindikasikan karakteristik hutan sekunder pada kedua lokasi.

Potential of Genome-Wide Association Studies and Genomic Selection to Improve Productivity and Quality of Commercial Timber Species in Tropical Rainforest, a Case Study of Shorea platyclados

Shorea platyclados (Dark Red Meranti) is a commercially important timber tree species in Southeast Asia. However, its stocks have dramatically declined due, inter alia, to excessive logging, insufficient natural regeneration and a slow recovery rate. Thus, there is a need to promote enrichment planting and develop effective technique to support its rehabilitation and improve timber production through implementation of Genome-Wide Association Studies (GWAS) and Genomic Selection (GS). To assist such efforts, plant materials were collected from a half-sib progeny population in Sari Bumi Kusuma forest concession, Kalimantan, Indonesia. Using 5900 markers in sequences obtained from 356 individuals, we detected high linkage disequilibrium (LD) extending up to >145 kb, suggesting that associations between phenotypic traits and markers in LD can be more easily and feasibly detected with GWAS than with analysis of quantitative trait loci (QTLs). However, the detection power of GWAS seems low, since few single nucleotide polymorphisms linked to any focal traits were detected with a stringent false discovery rate, indicating that the species’ phenotypic traits are mostly under polygenic quantitative control. Furthermore, Machine Learning provided higher prediction accuracies than Bayesian methods. We also found that stem diameter, branch diameter ratio and wood density were more predictable than height, clear bole, branch angle and wood stiffness traits. Our study suggests that GS has potential for improving the productivity and quality of S. platyclados, and our genomic heritability estimates may improve the selection of traits to target in future breeding of this species.

Genetic Diversity and Demographic History of an Upper Hill Dipterocarp (Shorea platyclados): Implications for Conservation

Southeast Asian rainforests at upper hill elevations are increasingly vulnerable to degradation because most lowland forest areas have been converted to different land uses. As such, understanding the genetics of upper hill species is becoming more crucial for their future management and conservation. Shorea platyclados is an important, widespread upper hill dipterocarp in Malaysia. To elucidate the genetic structure of S. platyclados and ultimately provide guidelines for a conservation strategy for this species, we carried out a comprehensive study of the genetic diversity and demographic history of S. platyclados. Twenty-seven populations of S. platyclados across its range in Malaysia were genotyped at 15 polymorphic microsatellite loci and sequenced at seven noncoding chloroplast DNA (cpDNA) regions. A total of 303 alleles were derived from the microsatellite loci, and 29 haplotypes were identified based on 2892 bp of concatenated cpDNA sequences. The populations showed moderately high genetic diversity (mean HE = 0.680 for microsatellite gene diversity and HT = 0.650 for total haplotype diversity) and low genetic differentiation (FST = 0.060). Bayesian clustering divided the studied populations into two groups corresponding to western and eastern Malaysia. Bottleneck analysis did not detect any recent bottleneck events. Extended Bayesian skyline analyses showed a model of constant size for the past population history of this species. Based on our findings, priority areas for in situ and ex situ conservation and a minimum population size are recommended for the sustainable utilization of S. platyclados.