& Key message Permanent sampling plots (PSPs) are a powerful and reliable methodology to help our understanding of the diversity and dynamics of tropical forests. Based on the current inventory of PSPs in Indonesia, there is high potential to establish a long-term collaborative forest monitoring network. Whilst there are challenges to initiating such a network, there are also innumerable benefits to help us understand and better conserve these exceptionally diverse ecosystems.

Indonesia offers a dramatic opportunity to contribute to tackling climate change by deploying Natural Climate Solutions (NCS), increasing carbon sequestration and storage through the protection, improved management, and restoration of drylands, peatlands, and mangrove ecosystems. Here, we estimate Indonesia's NCS mitigation opportunity for the first time using national datasets. We calculated the maximum NCS mitigation potential extent using datasets of annual national land cover, peat soil, and critical lands. We collated a national emissions factor database for each pathway, calculated from a meta-analysis, recent publications from our team, and available literature. The maximum NCS mitigation potential in 2030 is 1.3 ± 0.04 GtCO2e yr-1, based on the historical baseline period from 2009–2019. This maximum NCS potential is double Indonesia’s NDC (Nationally Determined Contribution) target from the Forestry and Other Land Use (FOLU) sector. Of this potential opportunity, 77% comes from wetland ecosystems. Peatlands have the largest NCS mitigation potential (960 ± 15.4 MtCO2e yr-1 or 71.5 MgCO2e ha-1 yr-1) among all other ecosystems. Mangroves provide a smaller total potential (41.1 ± 1.4 MtCO2e yr-1) but have a much higher mitigation density (12.2 MgCO2e ha-1yr-1) compared to dryland ecosystems (2.9 MgCO2e ha-1 yr-1). Therefore, protecting, managing, and restoring Indonesia’s wetlands is key to achieving the country’s emissions reduction target by 2030. The results of this study can be used to inform conservation programs and national climate policy to prioritize wetlands and other land sector initiatives to fulfill both Indonesia’s Nationally Determined Contribution (NDC) by 2030, while simultaneously providing additional co-benefits and contributing to COVID-19 recovery and economic sustainability.

Peat restoration is a key climate mitigation action for achieving Indonesia’s Nationally Determined Contribution (NDC) emission reduction target. The level of carbon reduction resulting from peat restoration is uncertain, owing in part to diverse methodologies and land covers. In this study, a meta-analysis was conducted to assess the impact of rewetting on reduction of total CO2 in soil and heterotrophic emissions at the country level. The tier 2 emission factor associated with the land cover category in Indonesia was also calculated. The analysis included a total of 32 studies with 112 observations (data points) for total CO2 emissions and 31 observations for heterotrophic emissions in Indonesia. The results show that the land cover category is not a significant predictor of heterotrophic and total soil emissions, but the highest observed soil emissions were found in the plantation forest. Using the random-effects model, our results suggest that an increase in the water table depth of 10 cm would result in an increase in total CO2 emissions of 2.7 Mg CO2 ha−1 year−1 and an increase in heterotrophic emissions of 2.3 Mg CO2 ha−1 year−1. Our findings show that managing water table depth in degraded peatlands in various land cover types is important to achieve Indonesia’s emission reduction target by 2030.

ABSTRAKVegetasi hutan tropika basah di Kalimantan pada umumnya didominasi oleh jenis dari famili Dipterocarpaceae. Namun dengan adanya kebakaran hutan di beberapa wilayah di Kalimantan, telah mengakibatkan berubahnya komposisi vegetasi penyusun hutan. Penelitian ini bertujuan untuk mengetahui keanekaragaman jenis vegetasi pada hutan bekas kebakaran tahun 1982/1983 dan 1997/1998 di daerah Sangkima, Taman Nasional Kutai. Pengumpulan data keragaman jenis vegetasi dilakukan dengan membuat empat plot temporer berukuran 100 m x 100 m, yang di dalamnya terdapat 25 sub plot berukuran 20 m x 20 m. Vegetasi yang diamati adalah pohon berdiameter lebih dari 10 cm. Hasil menunjukkan bahwa pada hutan bekas kebakaran di Sangkima Taman Nasional Kutai terdapat 163 jenis yang termasuk dalam 44 famili. Jenis dominan yang terdapat di hutan Sangkima antara lain: Eusideroxylon zwageri, Cananga odorata dan Macaranga gigantea. Kepadatan populasi berkisar antara 253 -372 pohon/ha dengan keanekaragaman jenisnya 61 -91 spesies/ha dan bidang dasar tegakan 17,63 -23,5 m 2 /ha. Kondisi hutan Sangkima Taman Nasional Kutai yang merupakan hutan bekas kebakaran merupakan faktor yang berpengaruh terhadap kepadatan populasi dan keanekaragaman jenis vegetasi di dalamnya.Kata kunci: vegetasi, hutan bekas kebakaran, Sangkima, Taman Nasional Kutai ABSTRACT Vegetation in tropical rainforest of Kalimantan is generally dominated by species from Dipterocarp family. However, forest fires in some areas of Kalimantan have resulted in the change in forest vegetation composition. This study was aimed to find out the diversity of vegetation at burned forests. Data were collected in

<p>Mahakam Delta is one of the largest mangrove ecosystem areas in East Kalimantan, which is dominated by nipa (<em>Nypa fruticans</em>). This paper investigates the population density of nipa and measures habitat characteristics in the area, which represents the condition of mangrove ecosystem that has received heavy pressures as a result of the increase in human activities.A total of 30 plots, size of 100m² each plot, were sampled from six locations in the study site. In each plot, the number of individual, stalk, leaves, fruit and flower of nipa was recorded. Nipa zone adjacent to active ponds area had the density of 106 individual/ha with 913 stalks ha^-1. The leaf density was 336 leaves ha^-1, fruit density was 12 fruits ha^-1 and flower density was 12 flowers/ha. Furthermore, nipa density in locations faraway from active ponds area was 74 individual/ha with 861 stalks/ha. While the leaf density was 239 leaves/ha, fruit density in this area was 2 fruits/ha and flower density was 9 flowers/ha. Result also showed that nipa habitat in study site is characterized by high turbidity and low salinity. Among other parameters, tidal level has strongest correlation to nipa population density. This study can also be considered as a preliminary assessment to develop mangrove ecosystem rehabilitation action plans in Mahakam Delta and to consider the potential use of nipa as an alternative source of livelihood for local communities living in the vicinity of the Mahakam Delta area.</p>