ABSTRAKMeningkatnya kandungan karbondioksida (CO 2 ) di atmosfer merupakan salah satu faktor penyebab terjadinya perubahan iklim dunia (global climate change). Penambatan karbondioksida melalui berbagai vegetasi hutan, misalnya di hutan mangrove diyakini sebagai salah satu upaya penurunan kandungan gas karbondioksida dari atmosfer. Avicennia marina (Forsk.) Vierh. sebagai salah satu jenis pohon pada tegakan mangrove memiliki potensi penambatan karbondioksida yang cukup besar. Selain melakukan pendugaan kandungan karbon pada tegakan Avicennia marina, juga dilakukan analisis karbon organik tanah. Kegiatan penelitian ini dilakukan di BKPH Ciasem, KPH Purwakarta, Perum Perhutani Unit III -Jawa Barat dan Banten. Dari lima plot pengambilan contoh tanah, diperoleh hasil rata-rata kandungan karbon organik tanah sebesar 2,9%. Kandungan karbon organik tanah ini tergolong sedang. Berdasarkan hasil dari sampling dengan merusak pohon di lapangan, diperoleh persamaan allometrik kandungan biomasa (Y) sebagai berikut: untuk biomasa atas Y = 0,1848(DBH) 2,3524 R 2 = 0,9839, untuk biomasa bawah Y = 0,1682(DBH) 1,7939 R 2 = 0,8581, dan untuk biomasa total Y = 0,2905(DBH) 2,2598 R 2 = 0,9815. Tegakan A. marina di BKPH Ciasem memiliki potensi kandungan biomasa total sebesar 364,9 ton/ha dan kandungan karbon sebesar 182,5 ton/ha. Nilai serapan CO 2 total tegakan A. marina (Forsk.) Vierh. di BKPH Ciasem adalah 669,0 ton/ha dengan nilai serapan CO 2 rata-rata 14,2 ton/ pohon. Kata kunci : Hutan mangrove, biomasa, sekuestrasi karbon I. PENDAHULUANKawasan hutan mangrove merupakan suatu kawasan yang berfungsi sebagai jembatan antara lautan dan daratan.Saat ini, hutan mangrove di dunia hanya tersisa sekitar 17 juta hektar; 22 % dari luas tersebut terdapat di Indonesia yang sebagian besar telah mengalami kerusakan dan perubahan status peruntukannya.

The increasing need for forest resources and cultivated land requires a solution in forest management to realize sustainable land use. Smart agroforestry (SAF) is a set of agriculture and silviculture knowledge and practices that is aimed at not only increasing profits and resilience for farmers but also improving environmental parameters, including climate change mitigation and adaptation, biodiversity enhancement, and soil and water conservation, while assuring sustainable landscape management. SAF, a solution for land management systems to reduce the rate of deforestation, is a smart effort to overcome the food crisis and mitigate climate change that is prospectively applied mainly in the social forestry area. Optimized forest land utilization could be achieved by implementing SAF and applying silvicultural and crop cultivation techniques to optimize productivity and meet sustainability and adaptability goals. This paper reviews the existing conditions, opportunities, and challenges in the mainstreaming of SAF in social forestry implementation to support the Sustainable Development Goals in Indonesia. Mainstreaming SAF should include policy innovation and regulation implementation, the use of appropriate technology, and compromises or trade-offs among benefits, risks, and resources. SAF is a strategy to revive the rural economy and community prosperity through the optimal use of local resources as well as a form of smart landscape and land-use management that has significant roles in soil and water conservation, bioenergy, climate change responses, and enhanced biodiversity conservation.

This paper provides an overview of the implementation and obstacles of watershed management, and the alternative solutions based on a synoptic review of related studies and experiences across Indonesia. The review found that problems in the institutional aspect were hierarchical confusion, discrepancy, and asynchrony among regulations, and weak (participation, synchronization, and coordination) among watershed management stakeholders. The weaknesses in the planning stage are integration among sectors, a lack of community participation, and limited readiness to integrate watershed planning into regional planning. Stakeholders’ involvement is also a critical factor in successful implementation of degraded watershed rehabilitation, including in peatland and mangrove areas. Failure should be minimized by providing adequate information on degraded watershed characteristics, appropriate species choices, and effective mechanical construction for soil and water conservation. Community participation as the main factor in driving watershed management should be achieved by strengthening public awareness of the importance of a sustainable watershed and providing access for the community to be involved in each stage of watershed management. Another problem is data gaps which are essential to address from the planning to evaluation stages. The gaps can be bridged by using remotely sensed data and by applying hydrological-based simulation models. Simplified criteria for watershed assessment may also be required, depending on site-specific issues and the watershed scale.

The decline in water resources and the occurrence of various hydrological disasters in the Citarum watershed indicate the need to restructure the components inside the watershed, especially land cover in the upper watershed area. This study aims to determine the effect of forest land cover on the hydrological parameters of the upstream Citarum watershed through simulations of the SWAT (Soil and Water Assessment Tool) model. The results showed that the forest cover in the Citarum watershed was only 15.96% of the watershed area and only 4.94% was located in the Upper area. The Flow Rate Coefficient of the upstream Citarum watershed is 31.4, the annual average surface flow and annual erosion are 933.03 mm and 517.9 tons/ha respectively. The simulation from several scenarios shows that a decreasing in forest area can increase discharge and surface runoff, whereas an increase in forest area will increase soil infiltration and evapotranspiration. Decreasing forest area by 10% from existing conditions caused 58% of rainwater to become surface runoff. The large number of discrepancies between the existing conditions and the directions in the RTRWP will require a long time and large costs to adjust so that the short-term alternative that can be done is to convert dryland agricultural cover to the forest to reach forest cover of at least 45% of the land area in the upstream area and can optimize the hydrological function of the watershed.

Indonesia diberkahi dengan banyaknya hutan alam meskipun sebagian dari hutan alam tersebut merupakan hutan bekas tebangan. Hutan-hutan alam tersebut berpotensi dapat mendukung Program Pemerintah untuk mengurangi emisi gas rumah kaca sebesar 26% sampai dengan tahun 2020 melalui kegiatan seperti Pengurangan Emisi dari Deforestasi dan Degradasi (REDD). Lanskap hutan bekas tebangan, dimana salah satunya terdapat di Kabupaten Malinau, Provinsi Kalimantan Timur, memiliki potensi biomasa karbon yang tinggi. Studi penelitian ini memperkirakan potensi biomasa karbon pada lanskap hutan bekas tebangan umur 5, 10 dan 30 tahun di Hutan Penelitian Malinau, Provinsi Kalimantan Timur, yang dikelola dengan skema pengelolaan lestari. Sampling tanah diambil secara random untuk mengukur kandungan karbon dalam tanah. Untuk analisis pendugaan biomassa karbon di atas permukaan tanah, telah ditempatkan tiga plot dimana setiap plot terdiri dari 25 subplot. Hasil penelitian menunjukkan bahwa kandungan karbon tanah pada hutan bekas tebangan setelah 5, 10 dan 30 tahun masing-masing adalah 46 tonC/ ha, 47 tonC/ha dan 30 tonC/ha, sementara itu biomassa tegakan di atas permukaan tanah masingmasing adalah 343,61 ton/ha, 392,56 ton/ha dan 498,19 ton/ha. Hasil penelitian ini menunjukkan bahwa biomassa karbon pada hutan alam bekas tebangan setelah 30 tahun dibawah pengelolaan hutan lestari memiliki biomassa karbon hampir sama dengan biomasa karbon di hutan alam primer yaitu 529,4 ton/ha dan 264,70 tonC/ha. Implikasi hasil penelitian ini adalah dapat digunakannya kandungan biomassa karbon di hutan bekas tebangan sebagai indikator untuk penilaian pengelolaan hutan lestari ( ).Kata kunci: Biomassa, karbon, hutan bekas tebangan, hutan alam ABSTRACTIndonesia is endowed with natural forests although part of them have been already logged-over forest. The natural forests potentially can support the Indonesian Government Program to reduce greenhouse gas emissions by 26% until the year 2020 through the activities such as Reducing Emission from Deforestation and Degradation (REDD). Logged-over forest landscape, one in Malinau District, East Kalimantan Province, has high carbon-biomass potency. This study estimated carbon-biomass potency of forest landscape in logged-over forest after 5, 10 and 30 years at Malinau Research Forest, East Kalimantan Province, managed under sustainable management scheme. Random sampling was conducted for soil sampling to measure carbon contents in the soil. For analysis of above ground carbon-biomass estimation, three plots were taken where each plot consist of subplot of 25. Result of the study showed that soil carbon content at logged over forest after 5, 10 and 30 years are 46 tonC/ha, 47 tonC/ha and 30 tonC/ha, respectively, while above ground biomass are 343.61 ton/ha, 392.56 ton/ha and 498.19 ton/ha, respectively. These results indicated that carbon-biomass in the natural forest logged under sustainable forest management after 30 years of logging has carbon-biomass similar with those of natural forests i.e. 529.4 ton biom...

Natural forest has many ecological functions which plays a vital role in preserving the ecosystem balance. One of them is to stabilize the climatic condition. This is linked with the forest capability to absorb carbondioxide in the photosynthesis process. The more carbondioxide absorbed and stored in the form of biomass carbon, the more it reduces greenhouse gas effect in the atmosphere. This paper discusses the carbon biomass potency of old growth forest and thirty year-old logged over forest in the Malinau Research Forest, located in East Kalimantan. Twenty centimeters depth of soil sampling was collected from five points representing each study site. Above ground biomass estimation was done by establishing four 1-ha plots for both forest sites. Within the 1-ha plot, 25 subplots with the size of 20 m x 20 m were also established. Trees with dbh ≥ 10 cm were recorded in terms of diameter and height. Tree biomass was estimated by employing Brown and Chave allometric equation. The study results showed that the soil carbon of 20 cm depth at old growth forest and the thirty year logged over forest were 37.86 tonC/ha and 30.58 tonC/ha, respectively. Further, the above ground carbon biomass of the old growth forest and the thirty year logged over forest were 264.70 tonC/ha and 249.10 tonC/ha, respectively. In conclusion, accumulation of carbondioxide in the old growth forest and the thirty year logged over forest for the past 30 years were 970.57 tonCO 2 /ha and 913.37 tonCO 2 /ha, respectively. It is of interest to note that the potency of natural forest in Malinau Research Forest in absorbing carbon is very high when it is managed sustainably. Tthe above ground biomass difference between the old growth forest and the 30 year logged over forest was only slightly. Keywords: Old growth forest, thirty year logged over forest, carbon biomass ABSTRAK Hutan alam memiliki fungsi ekologis yang sangat vital dalam menjaga keseimbangan ekosistem. Salah satu di antaranya adalah fungsi hutan alam dalam menjaga iklim di dalam kawasan hutan maupun di luar hutan. Hal ini terkait dengan kemampuan tegakan hutan untuk menyerap karbondioksida dan melepaskan oksigen dalam proses fotosintesis. Semakin banyak karbondioksida yang diserap oleh tanaman dalam bentuk biomasa karbon maka semakin besar pengaruh buruk efek gas rumah kaca dapat ditekan. Dalam tulisan ini, akan dibahas tentang potensi biomasa karbon hutan alam dan hutan bekas tebangan setelah 30 tahun di Hutan Penelitian Malinau, Kalimantan Timur. Pengambilan sampel tanah dilakukan dengan membuat lima titik sampling tanah secara acak dengan kedalaman 20 cm masing-masing di hutan alam dan hutan bekas tebangan setelah 30 tahun. Pengukuran biomasa karbon di atas permukaan tanah, dilakukan dengan membuat empat plot dan masing-masing plot dibuat subplot sebanyak 25 dengan ukuran 20 m x 20 m pada masingmasing hutan alam dan hutan bekas tebangan setelah 30 tahun. Pohon dengan diameter setinggi dada ≥ 10 cm diukur dan dicatat diameter dan tingginya. Biomas diukur dengan menggunakan metode B...

Bio-sequestration is one of the important carbon stock management that was underlined in several international meetings. Data on carbon stocks of vegetation and peat soil are very important to minimize variation of the carbon stock estimates in peat forests. The objectives of this research were to formulate the allometric equation for estimating tree biomass of the primary and burnt peat forests and to analyze the vegetation carbon stocks of the primary and burnt peat forests. The research was carried out in the primary peat forest (HGP), peat forest repeatedly-burnt annualy (HG 1 ), peat forest three years after fire (HG 3 ), and peat forest eight years after fire (HG 8 ). Cluster plots were established in each forest type representing the period after burning and undisturbed condition. Each cluster plot consisted of four circular subplots (radius of 7.32 m) and four circular annular plots (radius of 17.95 m). The total number of both circular subplots and annular plots was 16 respectively. Data on biomass carbon stock were collected on those plots. Results of this research showed that for estimating total tree biomass for all cluster, the most reliable allometric equation was Y = 0.061 (DBHxρxT) 1.464 .General allometric equation of all cluster is used for users in the field to calculate of stand biomass carbon stock. This general equation can be applied in all cluster due to the similarity of rainfall climatic zone range as 2,621-3,339 mm/year belongs to climatic zone of moist 1,500-4,000 mm/year (Brown et al., 1989). Allometric equation in each cluster was used for estimation of stand biomass carbon stock in each cluster. The most reliable allometric equation in primary peat forest was Y = 0.040 (DBHxρxT) 1.52 ; in peat forest repeatedly-burnt annualy was Y = 0.098 (DBH) 2.350 ; in peat forest three years after fire was Y = 0.084 (DBHxρxT) 1.376 ; in peat forest eight years after fire was Y = 0.024 (DBHxρxT) 1.667 . Total carbon stock from understorey, seedlings, saplings, poles and trees were 73.08 tonC/ha at HGP; 4.93 tonC/ha at HG 1 ; 13.64 tonC/ha at HG 3 ; and 26.13 tonC/ha at HG 8 , respectively. ABSTRAKBiosekuestrasi atau penyerapan karbondioksida oleh vegetasi merupakan salah satu pengelolaan cadangan karbon yang penting untuk digarisbawahi dalam setiap pertemuan internasional, tetapi ketersediaan data tersebut masih kurang lengkap dan tersebar. Data cadangan karbon dari vegetasi dan tanah gambut sangat penting untuk mengurangi variasi pendugaan stok karbon di hutan gambut. Tujuan penelitian ini adalah untuk memformulasikan persamaan alometrik dalam pendugaan biomassa pohon di hutan gambut primer dan bekas kebakaran serta untuk menganalisis cadangan karbon vegetasi di hutan gambut primer dan bekas kebakaran. Penelitian dilakukan di hutan gambut primer (HGP), hutan gambut bekas terbakar berulang tiap tahun (HG 1 ), hutan gambut bekas terbakar setelah tiga tahun (HG 3 ), dan hutan gambut bekas terbakar setelah delapan tahun (HG 8 ). Klaster plot dibuat di setiap hutan gambut primer dan bekas kebakaran...

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