AbstrakPembangunan hutan tanaman di lahan gambut tidak terlepas dari sorotan isu negatif lingkungan terkait dengan penurunan kedalaman muka air tanah, sehingga terjadi perubahan ekosistem asli. Kegiatan reklamasi lahan untuk HTI Acacia crassicarpa dalam jangka panjang disinyalir akan menimbulkan dampak negatif terhadap perubahan karakteristik tanah gambutnya seperti tingkat kematangan dan laju penurunan permukaan tanah gambut (subsiden). Kajian mengenai dampak pembangunan HTI di lahan gambut terhadap tingkat kematangan dan laju subsiden perlu dilakukan untuk memberikan informasi mengenai kondisi exsisting daya dukung lahannya. Penelitian ini bertujuan untuk mengevaluasi tingkat kematangan gambut baik secara vertikal (berdasarkan kedalaman gambut) maupun secara horizontal (berdasarkan jarak dari bibir kanal) dan mengetahui laju subsiden sebagai dampak dari reklamasi lahan gambut menjadi HTI A. crassicarpa. Penelitian dilakukan di PT AA, Distrik Rasau Kuning, Kabupaten Siak, Riau. Plot penelitian ditempatkan dalam satu transek sepanjang 100 m yang dibuat tegak lurus dengan kanal tersier, terdapat 12 plot dan dalam satu transek terdapat 3 titik pengamatan sehingga total titik pengamatan adalah 36 titik. Parameter yang diamati adalah dinamika kedalaman muka air tanah, nilai kadar serat tanah gambut dan laju subsiden. Hasil penelitian menunjukkan bahwa dampak perubahan kedalaman muka air tanah gambut di lokasi penelitian hanya mempengaruhi tingkat kematangan gambut pada kedalaman kurang dari 2 m, sedangkan jarak kanal tersier sebesar 125 m tidak berpengaruh secara nyata terhadap tingkat kematangan gambut. Pada kedalaman kurang dari 2 m tingkat kematangan gambut lebih tinggi dibandingkan dengan lapisan di bawahnya. Pembangunan HTI A. crassicarpa di lokasi penelitian menyebabkan laju subsiden sebesar rata-rata 5,5 cm/tahun. Kata kunci: hutan tanaman industri, kematangan gambut, lahan gambut, laju subsiden Abstract The establishment of forest on peat areas is insepatable from the glare of the negative environmental issues associated with a decrease in the depth of water table which then result in a change of the original ecosystem. Longterm land reclamation activities for HTI Acacia crassicarpa is supposed to give a negative impact on changes in the peat soil characteristics such as level of maturity and the rate of decrease in surface peat soil (subsidence). Studies on the impact of HTI development in peat areas particularly on the level of maturity and rate of subsidence need to be done in order to provide information regarding the carrying capacity of the land exsisting condition. This study aims at evaluating the maturity level of the peat either vertically (based on the depth of peat) or horizontally (based on the distance from the lips of the canal) and determining the rate of subsidence as a result of reclamation of peatlands into

Soil organic matter (SOM) is a crucial component of soil, through which physical, chemical, and biological characteristics interact in a local context. Within the forest category, the conversion of natural forests to monoculture plantations has raised concerns in Indonesia over the loss of soil functions, similar to conversion to agriculture. In natural forests, SOM can accumulate as part of a closed nutrient cycle with minimal nutrient losses; in plantation forestry, SOM decline and recovery can alternate over time, associated with larger nutrient losses. We reviewed existing studies to quantify how shifts from natural forests to short-rotation plantation forests (SRPF) affect SOM dynamics, soil nutrient contents, and soil-borne pathogens that cause disease. The review combines descriptive and quantitative methods (meta-analysis). The results show that conversion affects the soil C balance, soil structure and water balance, soil nutrient balance, and soil-borne diseases. Contributing factors include the reduced diversity of plant and rhizosphere communities, lower annual litter production, more uniform litter quality, and nutrient removal at the harvest cycle. Conversion from natural to plantation forest conditions also increases plant disease incidence by changing biological control mechanisms.

Puncak is a famous area for tourism, also for farming and as catchment area, located on hilly area with altitude of 330 -3002 m a.s.l, has 8 -50% slopes and belongs to Sub Catchment (Sub DAS) ABSTRAKPuncak merupakan kota pariwisata dengan bentuk penggunaan lahan untuk usahatani dan daerah resapan air. Secara umum kawasan ini merupakan daerah perbukitan dengan ketinggian bervariasi mulai dari 330 meter sampai 3.002 meter di atas permukaan laut, dengan kemiringan lahan antara 8% sampai dengan 50% dan terletak di kawasan Sub DAS Ciliwung Hulu. Persoalan utama di kawasan Puncak adalah perubahan penggunaan lahan yang terus terjadi dan meningkat dari tahun ke tahun. Selama periode tahun 1981 -2001 perubahan penggunaan lahan terluas terjadi pada permukiman. Hal ini menunjukkan bahwa kebutuhan akan pemukiman merupakan faktor terbesar yang mendorong perubahan fungsi lahan di kawasan Puncak. Penelitian ini bertujuan untuk melakukan monitoring perubahan penggunaan lahan di kawasan Puncak Kabupaten Bogor. Citra satelit multi waktu digunakan sebagai data utama dalam mendefinisikan tipe-tipe penggunaan lahan yang terjadi pada kurun waktu 1995 -2003. Analisis spasial dilakukan dengan menggunakan System Informasi Geografis yang dikembangkan oleh Aronoff (1989). Hasil analisis spasial menunjukkan perubahan luasan dari delapan tipe penggunaan lahan yaitu hutan, kebun teh, kebun campuran, pemukiman, tegalan, semak, lahan terbuka dan sawah. Perubahan penggunaan lahan yang penting terjadi diantaranya adalah hutan (34,96% pada tahun 1995 menjadi 28,07% pada tahun 2003), sedangkan pemukiman (8,79% pada tahun 1995 menjadi 32,28% pada tahun 2003). Pada tahun 2003, luas penggunaan lahan untuk pemukiman sudah menempati peringkat teratas dibandingkan dengan penggunaan lahan lainnya, sehingga apabila penambahan pemukiman tidak dapat ditekan maka akan berdampak meningkatnya aliran permukaan yang dapat menimbulkan erosi dan banjir yang berulang.

The benefits of revegetation provided by the successful growth of planted vegetations. This paper described a successful initiative on the revegetation of tropical degraded land using native trees. More than 250 hectares of intact landscape in Gunung Dahu, West Java—Indonesia have been successfully revegetated using 32 Dipterocarp species. The success of this 20-years-old revegetated landscape was revealed by timber volume, natural regeneration, soil characteristics, ectomycorrhiza occurrence, and ecotourism potential. The results showed that the average diameter and height were varied from 12–43 cm and 10–23 m; diameter mean annual increment were at 0.6–2.1 cm year−1; standing stock per hectares were at 10–220.84 m3 ha−1. The variations might be caused by different planted species, spacing distance, and planting technique. The natural regeneration success was observed by the offspring’s occurrence from six Shorea species and supported by mycorrhiza fruiting bodies predominantly by the genus Rusula. Planted trees also improved the availability of organic materials to the soils, as described by the good total soil porosity (51.06–52.32%) and infiltration rate (120–15,533 mm hour−1) at the site. The landscape also provided springs with continuous water supply and allowed tourists to experience the serenity of the tropical forest. Hence, revegetation using a native tree is prospective and proven to deliver a wider benefit in the ecological, economic, and social aspect.

Gunung Dahu Research Forest (GDRF) is a 250 ha tropical degraded land reforested by native dipterocarps species. The reforestation success was valued by evaluating the planted trees’ growth performance, their potential timber stock, natural regeneration capacity, soil improvement, biological interdependence, and environmental services. This scientific report used a combination of literature review and also primary data processing to describe the reforestation success within the area. A hilly species of Shorea platyclados showed the best growth performance with its average diameter and height of 43 cm and 23 m, respectively, with its mean diameter annual increment of 2.1 cm/year and the predicted standing stock at 220 m3/ha. Six Shorea species were identified to show their natural regeneration capacity and the occurrence of ectomycorrhizal fruiting bodies, predominantly by the genus Rusula, determined the establishment of biological interdependency at the site. Reforestation improved soil organic matters as revealed by high soil porosity (51.06–52.32%) and infiltration rate (120–155.33 mm/h). The reforested landscape also ensures a continuous water supply and provides an economic benefit for the community. Thus, planting native trees for reforesting degraded tropical landscapes is prospective and may deliver multiple benefits in an ecological and economic view.