No abstract

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.

The composition of soil-seed bank reflects the condition of vegetation in the past and could be used for predicting the composition of plants that will grow in the future. This study aims to determine the amount and composition of soil-seed bank in Bekol savanna, Baluran National Park. Soil samples were taken using a combination method of quadrat-transect on the invaded and not invaded areas by Acacia nilotica. Soil samples were extracted using wet-sieving method. After the extraction process, the seeds were identified and calculated using a stereo microscope. The result showed that soil-seed bank density was lower at the invaded location (7,566.88 seeds/m3) as compared to the uninvaded location (16,798.3 seeds/m3). The soil-seed bank was found in the invaded site comprising 12 species of broadleaved weeds and 5 species of grasses from 7 families, whereas those in the uninvaded area consisted of 10 species of broadleaved weeds and 7 species of grass from 8 families. This study showed that the invasion of A. nilotica significantly affected the amount and composition of soil-seed bank in various soil depths of Bekol savanna.