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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.

To date, performance of the management of Indonesian production forests are discouraging. The concession areas, timber production and employment have been decreasing over time. concern on these matter and to improve management, a research was conducted for six years (2008-2013) and resulted in recommendations to implement the Multi-System of Silviculture (MSS) systems. Two products were generated in MSS; criteria and indicator to guide the selection of appropriate silvicultural system and supersilvik, a model to develop the best business plans. This paper evaluates and strengthens the recommendations through the simulation of MSS products in PT. Sarmiento Parakantja Timber (Sarpatim), Central Kalimantan, Indonesia. Various data variables were used, such as thematic maps of forest areas, data of stand, materials, equipments, labors, finances and incomes. Data were processed in a variety of formulations which were connected to each other in model systems to produce a variety of outcomes, such as production, finance, employment and tax contributions. Results offer four options to improve PT. Sarpatim performance, one of which is the best choice. Compared to the former business model under limited silvicultural systems, MSS projected an increase in the use of land, timber production and employment by 151-753%. Implementing MSS will provide a better and healthier finance for company with an increase of NPV up to 193%; as well as for government tax revenues with an increase up to 308%. This MSS case study strongly suggests using the new theory that the management of production forests is a land and plant-based enterprises, which should put the land as the major capital and silvicultural aspects as the driving engine for production. The policy makers should be able to use these results as a reference in implementing MSS widely as part of Sustainable Forest Management (SFM) practices.

International audience; AbstractKey messageThis study assessed the effect of ecological variables on tree allometry and provides more accurate aboveground biomass (AGB) models through the involvement of large samples representing major islands, biogeographical zones and various succession and degradation levels of natural lowland forests in the Indo-Malay region. The only additional variable that significantly and largely contributed to explaining AGB variation is grouping based on wood-density classes.ContextThere is a need for an AGB equation at tree level for the lowland tropical forests of the Indo-Malay region. In this respect, the influence of geographical, climatic and ecological gradients needs to be assessed.AimsThe overall aim of this research is to provide a regional-scale analysis of allometric models for tree AGB of lowland tropical forests in the Indo-Malay region.MethodsA dataset of 1300 harvested trees (5 cm ≤ trunk diameter ≤ 172 cm) was collected from a wide range of succession and degradation levels of natural lowland forests through direct measurement and an intensive literature search of principally grey publications. We performed ANCOVA to assess possible irregular datasets from the 43 study sites. After ANCOVA, a 1201-tree dataset was selected for the development of allometric equations. We tested whether the variables related to climate, geographical region and species grouping affected tree allometry in the lowland forest of the Indo-Malay region.ResultsClimatic and major taxon-based variables were not significant in explaining AGB variations. Biogeographical zone was a significant variable explaining AGB variation, but it made only a minor contribution on the accuracy of AGB models. The biogeographical effect on AGB variation is more indirect than its effect on species and stand characteristics. In contrast, the integration of wood-density classes improved the models significantly.ConclusionOur AGB models outperformed existing local models and will be useful for improving the accuracy on the estimation of greenhouse gas emissions from deforestation and forest degradation in tropical forests. However, more samples of large trees are required to improve our understanding of biomass distribution across various forest types and along geographical and elevation gradients.

Ecological studies on mangrove forest in East Coast of North Sumatra have been carried out with field work in transect method and laboratory analyses. This study would be covered on floristic composition, abrasion, green belt, soil properties, and water quality of mangroves. Land system map and landsat TM imagery (year 1996 coverage) as main material in this study were used and overlay to determine training area. Based on vegetation inventory found that 20 mangrove species and by vegetation analyses, we known that Avicennia marina was as dominant tree species of seedling and sapling stage. Tree stage was not found in the area, yet. Environment properties of the mangrove area were suitable for mangrove growth and rehabilitation with the exception of pyrite content in the mangrove soil. Average of mangrove green belt was 25 m with range from 10 to 80 m in KJP (Kajapah) land system and 30 m with range 10 to 50 m in PTG (Putting) land system. Abrasion rate in the area was very high, i.e. 6 m per year in KJP land system, and 10 m per year in PTG land system.© 2008 Jurusan Biologi FMIPA UNS SurakartaKey words: mangrove, abrasion, green belt, soil properties, water quality, North Sumatra

Onrizal, Mansor M. 2015. Status of coastal forests of the Northern Sumatra in 2005 (after 2004's tsunami catastrophe) Biodiversitas 17: 44-54. The first intensive ecological study of coastal vegetation including mangrove, littoral and peat swamp forests after the 2004 tsunami catastrophe in Northern Sumatra was conducted from January to December 2005 where 16 sampling sites along 2960km coastline in Northern Sumatra were selected. In each site, one quadrate of 100 m x 100 m was established and divided into 10 m x 10 m subplots where all standing trees of ≥ 2 cm diameter at breast height (DBH) were identified to species level and measured. Overall 54,871 standing trees were recorded in 16 sites comprising 84 species in 65 genera and 37 families. Mangrove trees Rhizophora apiculata and R. mucronata were widely distributed and are dominant in most of the sampling sites. This indicated that these species have stronger resilient compared to other species. The highest value of Shannon-Wiener index of species and Evenness index of species was 3.03 and 0.85, respectively. It means that some sites were rich in biodiversity which harbors various species of plants. Subsequently, undisturbed coastal forests including mangroves, littoral forests and peat swamp forests characterized by dense stands, mixed species and structures play an important role in coastal protection against tsunami. Therefore, the coastal vegetation is needed to conserve the biodiversity and to maintain the production capacity as part of sustainable and longlasting vegetation bioshield.

The objective of the research was to know species composition and structure of ex-burned heath forest. Field research was carried out from 23 June to 5 July and 10 to 25 September 2004 on the foot-slope of Semujan Hill, Danau Sentarum National Park, West Kalimantan. Ten-sample units (SU) with each size 10 x 10 m are placed based on random sampling method. On each SU, trees with diameter  2 cm cm were identified and the diameter (DBH) and height are recorded. Fourteen tree species were found within a 0.1 ha SU, consisting of 12 genus and 8 families. Tree density is exponentially decreased from trees with small diameter to trees with big diameter.Key words: species composition, forest structure, ex-burned heath forest, Danau Sentarum National Park, West Kalimantan.