Abstract. Susilowati A, Rangkuti AB, Rachmat HH, Iswanto AH, Harahap MM, Elfiati D, Slamet B, Ginting IM. 2021. Maintaining tree biodiversity in urban communities on the university campus. Biodiversitas 22: 2839-2847. Many universities worldwide have green spaces (GS) as an integral part of their campuses because of significant benefits for ecological function and urban communities. University of Sumatera Utara (USU) campus is located in urban area of Medan city, Indonesia, with a total area of 120 hectares. The campus offers various outdoor spaces for resting, sports, playgrounds and other psychological benefits. The campus also offers vital benefits for its surrounding environment, such as improving air quality and ensuring pleasant climatic conditions and biodiversity. One of the important functions of USU GS is to become an area for preserving tree diversity in urban communities, which in busy urban communities is sometimes a little overlooked. This research aimed to identify the species diversity, abundance, utilization, and conservation status of trees across 120 hectares of USU Campus using the field inventory method. Results revealed a total of 7333 individual trees of 121 species from 37 families. The most common tree species is Swietenia macrophylla (18.37%), while the dominant families are Fabaceae. Margalef index and the Shannon-Wiener diversity index reaching 13.48 (good) and 3.41 (high). Based on the utilization status, 55.43% of the tree species were wood producers, 45.34% were pollutant absorbers, while the lowest percentage functioned as latex producers (0.12%). About 70 species (57.85%) were native species, while 51 species (42.15%) were exotic. According to the International Union for Conservation of Nature (IUCN), 50 species (41.33% %) were listed as the least concern status, 8 species (6.61%) with a vulnerable status, 4 species (3.30%) with a near-threatened status and 2 species (1.66%) with and endangered status. The result from this study also showed that GS at USU not only performed its main function as a shade or an oxygen producer (environment services) but also maintained the tree biodiversity and a means of ex-situ conservation for many trees species. Trees threatened by anthropogenic activities, particularly tree felling for infrastructural developments were still found in the campus area. Therefore, sustainable conservation efforts should be geared towards ensuring the continued existence of the trees to maintain their ecological functions

Susilowati A, Rachmat HH, Elfiati D, Hasibuan MH. 2019. The composition and diversity of plant species in pasak bumi’s (Eurycoma longifolia) habitat in Batang Lubu Sutam forest, North Sumatra, Indonesia. Biodiversitas 20: 413-418. Pasak bumi (Eurycoma longifolia Jack) is one of the most popular medicinal plants in Indonesia. Currently, E. longifolia is being over-exploited due to its potential and popularity as herbal medicine and its high value in the market. Therefore, the study on the population structure of the species and habitat characterization is required to ensure successfulness of conservation of this species. The study was carried out in lowland forest, located in Limited Production Forest within the Register Number 40, situated administratively in Papaso Village, Sub-District of Batang Lubu Sutam-Padang Lawas, North Sumatra, Indonesia. Batang Lubu Sutam forest is known as a source of pasak bumi material in North Sumatra. Every year tons of pasak bumi are collected from this forest and exported to Malaysia and surrounding countries. Due to illegal harvesting for its roots, pasak bumi has been seriously depleted in some areas in Batang Lubu Sutam forest. Therefore, current data on its population are needed for conservation effort of Batang Lubu Sutam's pasak bumi. The objectives of this study were to assess the structure of forest where pasak bumi grows and to determine the correct management for sustainability the future stocks. Vegetation analysis was carried out purposively in four transect belts, each consisting of five quadrats or plots. The results showed that the Importance Value Index of pasak bumi at seedling, sapling, pole and tree stages was 21.26%, 9.147%, 0, and 0 respectively. The Shannon Diversity Index (H) ranged between 3.050 and 3.220 and was inside its common value distribution. The evenness index was high, more than 0.85, at all stages of plant growth. The disappearance of pasak bumi at pole and tree stages indicates threatening condition for the sustainability of pasak bumi in the study sites because of excessive harvesting.

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Abstract. Susilowati A, Elfiati D, Rachmat HH, Yulita KS, Hadi AN, Kusuma YS, Batu SAL. 2020. Vegetation structure and floristic composition of tree species in the habitat of Scaphium macropodum in Gunung Leuser National Park, Sumatra, Indonesia. Biodiversitas 21: 3025-3033. Scaphium macropodum (Miq.) Beumee Ex K Heyne is a member of Malvaceae tree species and globally recognized as malva nut and locally known as ‘kembang semangkok’, ‘tempayang’, ‘merpayang’ or ‘kepayang’. The nut of S. macropodum has many benefits for medicinal purposes, yet destructive extraction of this tree species has led them to extinction. Among its natural distribution in Indonesia, North Sumatra Province, Indonesia is known as its original range, but there is limited information about the existence of this species. This study aimed to determine the vegetation structure of some tree species in the habitat of S. macropodum in Sikundur, Gunung Leuser National Park, Sumatra, Indonesia. Purposive sampling technique was employed by creating line transect at some forest areas where the population of S. macropodum is known to grow naturally. Four line transects with each transect consisting of five plots with nested plots within were established to record data at four growth stages, resulting in 80 plots in total. The results showed that the Important Value Index (IVI) of S. macropodum within the floristic community at the studied area was 21.98, 13.85, 27.30, and 39.60 for tree, pole, sapling, and seedlings stages, respectively. The Shannon-Wiener Diversity Index (H) were 3.80, 3.70, 3.06 and 2.45, Index of evenness (E) are 0.94, 0.92, 0.86, 0.77 and the Index of Richness (R) are 11.76, 10.73, 6.59, 4.10 for tree, pole, sapling, and seedlings stages. This result suggests that the natural population of S. macropodum in Sikundur forest was still in good condition at all stages from tree to seedling.

Abstract. Susilowati A, Rachmat HH, Elfiati D, Hidayat A, Hadi AN, Zaitunah A, Nainggolan D, Ginting IM. 2021. Floristic composition and diversity at Keruing (Dipterocarpus spp.) habitat in Tangkahan, Gunung Leuser National Park, Indonesia. Biodiversitas 22: 4448-4456. Dipterocarpus spp., or locally known as Keruing, is a wood-producing tree and has high economic value. Keruing also produces derivative products in oil and oleoresin, which are widely used as raw materials for medicines and perfumes. Keruing natural population has been severely declining caused by habitat alteration and also over exploitation. Therefore, information on the composition and diversity of the floristic community at their habitat is important as an initial step in designing conservation actions. This study aims to determine the floristic composition and diversity at the keruing habitat in the Tangkahan area, Gunung Leuser National Park (Gunung Leuser NP). A line transect has been used to establish a purposive sampling in particular forest areas where the population of the keruing is known to grow naturally. Four line transects, each with five nested plots, totaling 110 plots, were established to gather data at four growth stages. The results found 47 species at the seedling stage, 43 species at the sapling stage, 48 species at the pole stage and 65 species at the tree stage. There were three species of keruing in the research location, namely Dipterocarpus haseltii, Dipterocarpus costulatus and Dipterocarpus elongatus Korth with low IVI values ??at each stage. D. haseltii was only found at the seedling, pole and tree stage with IVI values ??of 0.32, 0.30, and 6.90, respectively. D. costulatus was only found at the tree level with an IVI value of 3.43, while D. elongatus found at the sapling and tree stage with an IVI of 0.30 and 3.42, respectively. The diversity index in the research location was in the medium category at the seedling, sapling, and pole levels with a value of 2.96, 2.86, and 2.92, respectively and was classified as high at the tree level with a value of 3.18. The evenness index (E') in all growth stages is high or evenly distributed with the value of E' > 0.75. The species diversity in research location classified into medium-high category although in each stage showing dynamic on species domination. Disturbed habitat due to illegal logging and land conversion caused a problem on keruing regeneration. Conservation efforts, including active monitoring keruing occurrence, ex-situ conservation, and artificial regeneration, are needed to avoid keruing from extinction.