New surveys provide higher estimate of Sumatran orangutans than previously, but future scenarios indicate decline continues.

To conserve biodiversity scientists monitor wildlife populations and their habitats. Current methods have constraints such as the costs of ground or aerial surveys, limited resolution of freely-available satellite images, and expensive high resolution satellite images. Recently researchers started to use unmanned aerial vehicles (aka UAVs or drones) for wildlife and habitat monitoring. Here we tested whether we could detect nests of the critically endangered Sumatran orang-utan on imagery acquired from camera mounted drone to determine distribution and density. Our results show that the distribution of nests compares well between aerial and ground based surveys and that relative density (nest/km) shows a significant correlation between these two survey types. The results also indicate that both methods can be used to detect significant differences in relative density between previously degraded reforested and enriched areas. We conclude that orang-utan nest surveys from drones are a promising survey method to determine distribution and (relative) density of this and perhaps other ape species.

Abstract. Rambey R, Susilowati A, Rangkuti AB, Onrizal O, Desrita, Ardhi R, Hartanto A. 2021. Plant diversity, structure and composition of vegetation around Barumun Watershed, North Sumatra, Indonesia. Biodiversitas 22: 3250-3256. Watershed ecosystem plays an important role in water and soil conservation which is supported by vegetation around watershed. As such, vegetation analysis is beneficial to assess the current state of watershed vegetation and monitor future changes. Barumun Watershed, located in South Labuhanbatu District, North Sumatra Province, Indonesia, is under threat due to habitat degradation and land conversion for plantation and agriculture. This research aimed to investigate the diversity, structure and composition of vegetation in the Barumun River including its smaller streams (rivulets). Data were collected using a combination of line transect and quadratic plots arranged systematically. The total observation plots were 48 plots, consisting of 24 plots in Barumun River, 12 plots in Tasik Rivulet and 12 plots in Titi Kembar Rivulet. The results documented a total of 51 plants in the studied sites in Barumun Watershed in which 37 species were found in Barumun River, 20 species in Tasik Rivulet and 17 species in the Titi Kembar Rivulet. Plant species consisted of several habitus including herbs, palms, shrubs, climbers and trees. The trees consisted of 22 species (43.13%), herbs 22 species (43.13%), climbers 3 species (5.88%), shrubs two species (3.92%), and palm two species (3.92%). The highest Importance Value Index (IVI) for tree community was recorded in the Barumun River from Hevea brasiliensis (108.28), followed by Cryptocarya sp. (123.24) in the Titi Kembar Rivulet. In addition, the highest IVI for pole, sapling, seedling, and shrub was recorded from Muntingia calabura (Barumun River), Nauclea orientalis (Tasik Rivulet), Psychotria viridiflora (Tasik Rivulet), and Calamus axillaris (Titi Kembar Rivulet), respectively. The plant diversity in Barumun Watershed was categorized from low to moderate level of richness.

Forests in Indonesia that have high biodiversity, including one of them is the type of fern. The characteristic of Indonesian tropical rainforests is that they have high rainfall so that they strongly support the existence of this type of fern. In general, ferns like humid habitat conditions. The purpose of this study was to determine the types of ferns around the campus Sumatera Utara. The method of this research is by roaming, namely exploring each location that can represent the location where there is the most vegetation. The number of types of ferns found on the campus of the Universitas Sumatera Utara is 20 types. There are 9 families in the research location, including the polypodiaceae family as much as 35%, Pteridaceae (20%), Thelypteridaceae (15%), Nephrolepidaceae (10%), Aspleniaceae (10%), Athyriaceae (5%), Dryopteridaceae (5 %) and Blechnaceae (5%). There are 13 types that grow epiphytic and 7 that live terrestrially. The host trees for epiphytic ferns include Swietenia mahagoni, Elaeis guineensis, Gmelina arborea, Samanea saman and Paraserianthes falcataria.

Medan Zoo is an ex situ conservation area for several wildlife species, covering an area of approximately 30 hectares, most of which are green open space and provide a forage garden for Sumatran elephants. This study aims to determine the characteristics of vegetation and the diversity of natural food types for elephants available in the Medan Zoo. Data collection using purposive sampling method, carried out in the forage garden which located in several points of elephant free-range. Based on the calculation of the Shannon-Wienner index, the overall diversity of plant species at the research location is 3.7 which can be categorized as high. The dominant understorey plants in the elephant forage garden are species from the family of Poaceae, namely Paspalumconjugatum, Eragrotisamabilis, Ottochloanodosa. Meanwhile, for speciesof trees habitus, the dominance for each level of vegetation starting from the tree, poles and saplings were: Meliaazedarach, Hibiscus tiliaceus and Cassia sp. There are types of elephant feed plants, classified into 8 families.The dominant type of natural feed is from the family of Poaceae.