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Rangkuti AB, Hartini KS, Susilowati A, Rambey R, Harahap MM, Arinah H, Irmayanti L, Pamoengkas P, Indriani F, Peniwidiyanti, Ruhidi A. 2023. Structure, composition and diversity of tree species in Martelu Purba Nature Reserve, North Sumatra, Indonesia. Biodiversitas 24: 78-85. Martelu Purba Nature Reserve is one of the conservation areas in North Sumatra that functions to protect biodiversity. However, there is limited information related to the vegetation community contained in the nature reserve. This study aimed to assess the diversity, structure and composition of tree species in the Martelu Purba Nature Reserve as well as to reveal the conservation status of the species in reserve. The research used the line transect method with a total of 112 observation plots representing various vegetation and environmental conditions. The results showed that there were 39 tree species belonging to 25 families, with 31, 25, 24, and 26 species at the tree, pole, sapling, and seedling stages, respectively. Shorea platyclados and Syzygium cerasiforme were species with the highest Important Value Index (IVI) at the tree and pole stages with 173.04% and 31.01%, respectively, while Gamblea malayana was the most important at the sapling and seedling stages with IVI of 66.43%, and 30.00%, respectively. The Shannon-Wiener diversity index (H') was categorized as low (1.58), the Margalef species richness index (DMg) was high at all growth stages, and the Evenness index (E) was high, indicating that all species were evenly distributed across the research plots. The distribution of tree diameter classes ranged from 20 - 40 cm for trees with the smallest diameter to 81-110 cm for trees with the largest diameter. Based on their conservation status, there were two species with conservation concerns, namely Coffea arabica (Endangered) and Lithocarpus maingayi (Vulnerable). The application of good silvicultural methods needs to be carried out in the context of conservation efforts. One example is through vegetative propagation of species with long flowering periods.

Rachmat HH, Susilowati A, Elfiati D, Hartini KS, Faradillah WN. 2017. Short Communication: Strong genetic differentiation of the endemic rosin-producing tree Styrax sumatrana (Styracaceae) in North Sumatra, Indonesia. Biodiversitas 18: 1331-1335. Styrax sumatrana is an economically important rosin-producing tree endemic to North Sumatra, Indonesia. Distribution of this species is very limited, and the high rate of forest degradation in Sumatra is increasing the necessity for conservation. To quantify genetic variation and population structuring, we collected individuals from 3 populations namely Pakpak Bharat, Humbang Hasundutan (Humbahas) and Tapanuli Utara in which each of the population was represented by 10 individuals. However, the successful rate of amplification was varied among populations and for later analysis, we only took an account those sequences showing clear electropherograms and disposed those which showed ambiguity. We sequenced trnL-trnF chloroplast DNA (cpDNA) region yielded 941 bp after alignment. The trnL-trnF assigned the species into 4 haplotypes in which Pakpak Bharat was differentiated significantly and not shared any similar haplotypes with two others populations. Humbahas and Tapanuli Utara was shared one common haplotype. Mean nucleotide diversity at silent sites ranged 0 - 3.33 x 10-3, while nucleotide diversity at non-synonymous site ranged 0 - 5.9 x 10-4. Strong genetic differentiation was also found among 3 origin populations, with the highest pairwise genetic differentiation found on Pakpak Bharat and Tapanuli Utara (FST= 0.80952). Clear and apparent genetic structuring was possibly caused by geographical barriers such as highland and mountain ranges (Bukit Barisan mountain ranges) which acted as effective barriers to gene flow among population. The findings suggest that conservation efforts should focus on every population because each of the population maintains distinct genetic identity.