Abstract. Degradation of tropical peats is a global concern due to large Carbon emission and loss of biodiversity. The degradation of tropical peats usually starts when the government drains and clears peat forests into open peats used for food crops, oil palm and industrial timber plantations. Major properties of tropical peat forests are high in Water Contents (WC), Loss on Ignition (LOI) and Total Organic Carbon (TOC), and low in peat pH, Dry Bulk Density (DBD), and Total Nitrogen (TN). In this study, we investigated impacts of drainage and land use change on these properties. We collected peat samples from peat forests, logged over peat forest, industrial timber plantation, community agriculture, and oil palms. We used independent t-tests and oneway ANOVA to analyze mean differences of the research variables. We found that peat pH, DBD, and TN tend to increase. A significant decrease of C/N ratio in oil palm and agriculture sites importantly denotes a high rate of peat decompositions. Water contents, LOI, and TOC are relatively constants. We suggest that changes in pH, DBD, TN and atomic C/N ratio are important indicators for assessing tropical peat degradation. We infer that land use change from tropical peat forests intoCorrespondence to: G. Z. Anshari (gzanshari@live.untan.ac.id) cleared and drained peats used for intensive timber harvesting, oil palms and industrial timber plantations in Indonesia has greatly degraded major ecological function of tropical peats as Carbon storage.

Nusantara RW, Aspan A, Alhaddad AM, Suryadi UE, Makhrawie, Fitria I, Fakhrudin J, Rezekikasari. 2018. Peat soil quality index and its determinants as influenced by land use changes in Kubu Raya District, West Kalimantan, Indonesia. Biodiversitas 19: 535-540. Tropical peatland is continuously damaged in large area in Indonesia, caused by deep and wide drains which change the ecosystem. This research was conducted to evaluate the soil quality index (SQI) based on peatland use. The research was conducted in Kubu Raya District, West Kalimantan Province, in secondary peat forest, shrubland, oil palm plantation and corn field. The variables observed in this research were subsidence, water-table level, depth of peat, bulk density, water content, porosity, organic carbon, total nitrogen, total potassium, cation exchange capacity, base saturation, ash content, available phosphorus, and exchangeable calcium, magnesium, sodium, C/N ratio and soil acidity. The results showed that SQI in secondary peat forest, shrubland, corn field and palm oil plantation were 0.40, 0.37, 0.37 and 0.37 respectively. The stepwise regression analyses showed that the variables influencing SQI were the depth of peat, water-table level, and ash content. Secondary forest had the highest level (0.74) for the depth of peat with 509 cm depth while the other sites had average level (0.41-0.43) with 108.4 cm-115.5 cm mean depth. SQI of peatland increased with the increasing depth of peat and ash content. The differences showed that land use change of peatland, from forest to plantation area would decrease its SQI.

No abstract

Saidy AR, Mariana ZT, Adji FA, Nusantara RW, Fitria I, Syahrinudin. 2018. Carbon mineralization dynamics of tropicalpeats in relation to peat characteristics. Biodiversitas 19: 1413-1421. Understanding the dynamics of carbon mineralization of peats inthe tropical areas is of essential significance in controlling carbon dioxide (CO2) gas emission rates. An incubation study of tropicalpeats sampled from 3 different sites of the Barito Basin on the Borneo Island, Indonesia (uncultivated, used for paddy cultivation for  5years and 5-10 years) was carried out to investigate a relationship between CO2 production and peat characteristics. Results of studyrevealed that land use change from uncultivated peats to paddy fields resulted in significant changes in the chemical structure of peatorganic carbon. Carbohydrate contents of the peat decreased significantly as a consequence of the conversion of natural peats to paddyfields. However, the paddy peats contained higher lignin than uncultivated peats. Changes in the chemical structure of the tropical peatsresulted in changes in carbon mineralization. Carbon mineralization of uncultivated peats ranged from 29255310 mg CO2-C kg-1 peat,while carbon mineralization of 10652678 mg CO2-C kg-1 C peat was observed for paddy peats. Moreover, carbon mineralization dataobtained from the experiment fitted properly to a two-pool C mineralization model. The developed carbon mineralization model showedthat slowly and rapidly decomposable pools have a close relation with rubbed fiber and carbohydrate content data. Thus, results of thisstudy suggested that carbon mineralization of peats could be estimated appropriately using rubbed fiber and carbohydrate content data.

Lahan gambut di Kota Pontianak sering mengalami kebakaran yang berulang hampir setiap tahun. Tutupan lahan gambut yang terbakar beragam, mulai dari semak belukar hingga kebun masyrakat seperti akasia, kelapa sawit dan kebun campuran. Selain melepaskan emisi CO2 pada saat kebakaran berlangsung, lahan gambut yang mengalami perubahan fisik dan kimia akibat kebaarakan dapat mempengaruhi jumlah emisi CO2 yang dilepaskan ke atmosfer pasca terjadinya kebakaran.  Penelitian ini bertujuan untuk mengukur jumlah emisi CO2 pada lahan gambut yang terbakar pada pertengahan tahun 2018 di Kota Pontianak serta menganalisis korelasinya dengan beberapa faktor lingkungan. Penelitian dilakukan pada bulan Mei- Juli 2019 di Kota Pontianak Provinsi Kalimantan Barat pada lahan gambut pasca kebakaran dengan vegetasi awal berupa tanaman akasia dan vegetasi saat dilakukan penelitian berupa semak belukar. Pengukuran Emisi CO2 menggunakan metode sungkup tertutup dengan alat ukur portable EGM 4 (Infra Red Gas Analyzer). Selain itu dilakukan pula pengambilan sampel tanah untuk menganalisis beberapa karakteristik fisik (bobot isi, kadar air gravimetrik, muka air tanah) dan kimia gambut ( kandungan bahan organik, kadar abu, kadar C Organik, pH dan Eh tanah) serta pengukuran variabel lingkungan (suhu udara dan suhu tanah). Hasil penelitian menunjukan bahwa nilai fluks CO2 pada selama periode pengukuran berkisar dari 183 – 595 ton CO2 dengan rerata sebesar 416,07 t CO2 ± 92,99 . Emisi CO2 ini berkorelasi tidak nyata dengan variabel lingkungan. Selain mengindikasikan kompleksitas proses dekomposisi gambut sebagai penghasil emisi CO2 di lahan pasca kebakaran yang tidak dapat dikaitkan dengan variabel lingkungan tertentu, hal ini menunjukkan perlunya melakukan pengukuran dalam jangka waktu yang lebih panjang agar pola emisi dapat terlihat.