Natural forests in South-East Asia have been extensively converted into other land-use systems in the past decades and still show high deforestation rates. Historically, lowland forests have been converted into rubber forests, but more recently, the dominant conversion is into oil palm plantations. While it is expected that the large-scale conversion has strong effects on the carbon cycle, detailed studies quantifying carbon pools and total net primary production (NPPtotal ) in above- and belowground tree biomass in land-use systems replacing rainforest (incl. oil palm plantations) are rare so far. We measured above- and belowground carbon pools in tree biomass together with NPPtotal in natural old-growth forests, 'jungle rubber' agroforests under natural tree cover, and rubber and oil palm monocultures in Sumatra. In total, 32 stands (eight plot replicates per land-use system) were studied in two different regions. Total tree biomass in the natural forest (mean: 384 Mg ha(-1) ) was more than two times higher than in jungle rubber stands (147 Mg ha(-1) ) and>four times higher than in monoculture rubber and oil palm plantations (78 and 50 Mg ha(-1) ). NPPtotal was higher in the natural forest (24 Mg ha(-1)  yr(-1) ) than in the rubber systems (20 and 15 Mg ha(-1)  yr(-1) ), but was highest in the oil palm system (33 Mg ha(-1)  yr(-1) ) due to very high fruit production (15-20 Mg ha(-1)  yr(-1) ). NPPtotal was dominated in all systems by aboveground production, but belowground productivity was significantly higher in the natural forest and jungle rubber than in plantations. We conclude that conversion of natural lowland forest into different agricultural systems leads to a strong reduction not only in the biomass carbon pool (up to 166 Mg C ha(-1) ) but also in carbon sequestration as carbon residence time (i.e. biomass-C:NPP-C) was 3-10 times higher in the natural forest than in rubber and oil palm plantations.

Meriem S., Tjitrosoedirjo S., Kotowska M.M., Hertel D., Triadiati T., 2016. Carbon and nitrogen stocks in dead wood of tropical lowland forests as dependent on wood decay stages and land-use intensity. Ann. For. Res. 59(2): 299-310.Abstract. Rapid transformation of natural forests into other land-use systems in the lowlands of Sumatra, Indonesia, strongly reduces total aboveground biomass and affects nutrient cycling. However, the consequences of this conversion for C and N stocks of dead wood remains poorly understood particularly in natural forests and jungle rubber. This study examined the differences in dead wood abundance, mass, and C, N and lignin concentrations of three decay stages of dead wood as well as the stocks of these chemical components stored in dead wood. Standing and fallen dead wood was determined as coarse woody debris with diameter ≥ 10 cm and classified into three decay stages of wood. Mass of dead wood was estimated using allometric equation. Total C and N stocks in dead wood in the natural forests (4.5 t C ha -1 , 0.05 t N ha -1 , respectively) were three times higher than those in the jungle rubber (1.5 t C ha -1 , 0.02 t N ha -1 , respectively). The stocks of C and N at early and advanced wood decay stages in the natural forests were also higher than those in the jungle rubber. The decay stages showed pronounced differences in concentrations of chemical components. With advancing stage of wood decay, N concentration increased and C/N ratio decreased, while concentrations of C and lignin were variable. The distribution of dead wood mass and stocks of C, and lignin were found to be higher in the early decay than those in the advanced decay stage. Higher input of dead wood in natural forests indicated a higher importance of dead wood decay in natural forests than in jungle rubber systems. Thus, replacing natural forests with jungle rubber strongly reduces total C and N stocks which might have a marked negative effect on the ecosystems' nutrient turnover and cycle.

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Bakteri endofit merupakan kelompok mikroba endofit yang hidup di dalam jaringan tanaman tanpa menyebabkan dampak negatif , berhubungansecara mutualisme dengan inangnya, dapat diisolasi dari seluruh bagian tanaman  yaitu akar, batang , dan daun. Bakteri endofit mempunyai potensi sebagai agen pengendali biologi organisme pengganggu tanaman, sebagai pemacu kesehatan dan pertumbuhan tanaman. Pertumbuhan bakteri endofit umumnya memerlukan medium dengan kandungan nutrisi yaitu makronutrisi terdiri dari unsur (C, H, O, dan  N), mikronutrisi terdiri dari unsur non logam (S dan P) , unsur logam (Ca, Zn, Na, K, Cu, Mn, Mg, dan Fe), vitamin, tetapi untuk memenuhi syarat pertumbuhan tersebut umumnya masih menggunakan medium sintetis dengan harga yang tidak terjangkau oleh petani. Tujuan penelitian untuk memperoleh medium alternatif  berbahan alami yang dapat digunakan untuk menumbuhkan dan memperbanyak bakteri endofit dari tanaman terung dataran rendah. Penelitian dilakukan menggunakan Rancangan Acak Lengkap dengan 5 faktor bahan alami medium yaitu tepung (kacang kedelai, kacang hijau, kacang tanah, kacang tunggak, kacang merah) dan 1 faktor medium Nutrient Agar (NA). Tahapan pelaksanaan penelitian yaitu pemurnian koleksi isolat bakteri endofit asal tanaman terung dataran rendah pada medium NA, pembuatan medium berbahan alami, pengamatan meliputi  masa inkubasi, bentuk dan wajah koloni, jumlah dan diameter koloni bakteri endofit. Data dianalisa menggunakan analisa ragam dan BNT 5%. Hasil menunjukkan bahwa bakteri endofit asal tanaman terung dataran rendah tumbuh pada semua medium berbahan alami, medium berbahan alami tepung kacang kedelai berpengaruh terbaik terhadap pertumbuhan bakteri endofit.

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