Joeni Setijo Rahajoe

The distribution of mercury around the small-scale gold mining area along the Cikaniki river, Bogor, Indonesia.

The distribution of mercury in the soil, sediment and river water around the artisanal small-scale gold mining (ASGM) area along the Cikaniki River, West Java, Indonesia, was investigated. The total mercury concentration (T-Hg) in the forest soil ranged from 0.11 to 7.0mgkg(-1), and the highest value was observed at the ASGM village. In the vertical T-Hg profile around the villages, the highest value was observed at the soil surface, and the concentration decreased with depth. This result suggested that the mercury released by mining activity was dispersed through the atmosphere and deposited on the surface. The total organic carbon content (TOC) showed a similar vertical profile as the T-Hg, and a linear relationship was found between T-Hg and TOC. Mercury deposited on the surface can be absorbed by organic matter. The slope of the line was larger near the ASGM village, implying a higher rate of deposition of mercury. The T-Hg in the sediment ranged from 10 to 70mgkg(-1), decreasing gradually toward the lower reaches of the river. Mining waste can be transported with the river flow and deposited along the river. The distribution of the mining waste can be determined using the mineralogical composition measured by X-ray fluorescence spectrometry.

Variation in longevity and traits of leaves among co-occurring understorey plants in a tropical montane forest

The relationship between leaf longevity and other leaf traits was compared among different life-form categories (trees, herbs, climbers and epiphytes) of 101 plant species in a tropical montane forest on Mt. Halimun, West Java, Indonesia. We applied the Cox proportional hazards regression to estimate the leaf longevity of each species from 30 mo of census data. We examined whether estimated longevity was explained by either species life-form categories, taxonomic groupings (eudicots, monocots, magnoliids and chloranthales, and ferns) or such leaf traits as leaf area, leaf mass per area (LMA), mass-based leaf nitrogen, penetrometer reading, condensed-tannin-free total phenolics and condensed tannin. There was a wide-ranged interspecific variation in leaf longevity, mostly 10-50 mo, similarly across life-form categories. LMA showed a strong positive influence on leaf longevity. We found that relationships between leaf longevity and some leaf traits were different among various life forms. Trees tended to have high LMA, while climbers tended to have low LMA at the same leaf longevity. We hypothesize that such difference among life forms reflects shoot architecture characteristics. Multi-shoot trees with branching architecture need to have self-supporting leaves, whereas semi-epiphytic climbers can maintain relatively low biomass investment to leaves hanging or relying upon the mechanical support from host plants.

Using native epiphytic ferns to estimate the atmospheric mercury levels in a small-scale gold mining area of West Java, Indonesia.

Mercury pollution is caused by artisanal and small-scale gold mining (ASGM) operations along the Cikaniki River (West Java, Indonesia). The atmosphere is one of the primary media through which mercury can disperse. In this study, atmospheric mercury levels are estimated using the native epiphytic fern Asplenium nidus complex (A. nidus) as a biomonitor; these estimates shed light on the atmospheric dispersion of mercury released during mining. Samples were collected from 8 sites along the Cikaniki Basin during September-November, 2008 and September-November, 2009. The A. nidus fronds that were attached to tree trunks 1-3m above the ground were collected and measured for total mercury concentration using cold vapor atomic absorption spectrometry (CVAAS) after acid-digestion. The atmospheric mercury was collected using porous gold collectors, and the concentrations were determined using double-amalgam CVAAS. The highest atmospheric mercury concentration, 1.8 × 10(3) ± 1.6 × 10(3) ngm(-3), was observed at the mining hot spot, and the lowest concentration of mercury, 5.6 ± 2.0 ngm(-3), was observed at the remote site from the Cikaniki River in 2009. The mercury concentrations in A. nidus were higher at the mining village (5.4 × 10(3) ± 1.6 × 10(3) ngg(-1)) than at the remote site (70 ± 30 ngg(-1)). The distribution of mercury in A. nidus was similar to that in the atmosphere; a significant correlation was observed between the mercury concentrations in the air and in A. nidus (r=0.895, P<0.001, n=14). The mercury levels in the atmosphere can be estimated from the mercury concentration in A. nidus using a regression equation: log (Hg(A.nidu)/ngg(-1))=0.740 log (Hg(Air)/ngm (-3)) - 1.324.

Forest Structure and Productivity of Tropical Heath and Peatland Forests

Allometric relationships between tree dimensions, aboveground forest structure and productivity were examined in tropical heath (kerangas) forest and peatland forest in Central Kalimantan, to determine the stand level properties of these forest types growing under stressful conditions, by comparing with those in mixed dipterocarp forests. In the peatland forest, tree density, trunk diameter-height relationships and aboveground biomass differed between sites, partly due to differences in disturbance history such as the intensity of selective logging in the past. The heath and peatland forests shared common characteristics such as high leaf mass per area and long leaf residence time at the stand level. Both forest types had high wood mass increment rates (maximum of 8.2 Mg ha−1 year−1 in the heath forest and 10.9 Mg ha−1 year−1 in the peatland forest), which fluctuated greatly during and after the severe 1997–1998 drought. The results here suggest that the heath and peatland forests maintain moderately high productivity under stressful conditions, probably owing to the adaptive leaf properties. The results also suggest that the aboveground forest structure of these forest types as well as peat deposit has the potential to play a significant role in the carbon balance in an area. To be able to properly conserve these forest ecosystems, more attention must be paid to elucidating the mechanisms maintaining primary productivity of heath and peatland forests.

Stok Karbon dan Biomasa Beberapa Komoditas Tanaman Pertanian Di Bodogol- Taman Nasional Gunung Gede Pangrango – Jawa Barat

The study of carbon stock and biomasa of agricultural commodities was conducted in the Bodogol village, Gunung Gede Pangrango National Park - West Java. The purpose of this research to determine the biomasa, carbon stock and the rate of decomposition of agricultural commodities by using destructive sample and litterbag method. Six of agricultural commodities: green beans/buncis (Phaseolus vulgaris), chilli (Capsicum annum), corn (Zea mays), bean (Vigna cylindrica), peanuts (Arachis hypogaea) and cassava (Manihot esculenta), were calculated their biomasa and carbon stocks. The result showed that the biomasa of agriculture commodities in the range of 0.152 to 4.216 t ha-1, with a carbon stock ranging from 0.01 to 1.83 t ha-1. The decomposition rate (k) of those commodities were k = 5.6 y-1; 5.48 y-1, 5.18 y-1, 5.04 y-1, 4.42 y-1, and k = 1.21 y-1, for Manihot esculenta, Vigna cylindrica, Arachis hypogea, Zea mays, Capsicum annum and Phaseolus vulgaris, respectively.

Floristic Diversity in the Peatland Ecosystems of Central Kalimantan

Tropical peatlands have accumulated huge amounts of carbon. However, the carbon pool is presently disturbed by land utilization practices, and consequently it is becoming vulnerable to the effects of the changes. Tropical peatlands present a threat if they switch from being carbon sinks to carbon sources for the atmosphere. In the present state they provide a number of ecosystem services, such as biodiversity, habitat maintenance, water cycling, and commodities for exploitation. Tree diversity in the peatland forests of various study sites in Central Kalimantan are described here. In the Sebangau, Bawan, and Hampangen villages, the trees species were only 42.5 % of the total number of tree species found in the peatland forest. The estimates of above-ground biomass was about 331 t ha−1, and the litterfall around 6.5–9.1 t ha−1 year−1. The litterfall varied among locations, different in the degraded and intact peatland forests, and the nitrogen and carbon input of litterfall in these peatland forest types were 39.1 and 2,724 kg ha−1 year−1, respectively.

Peat-Fire Impact on Forest Structure in Peatland of Central Kalimantan

Tropical peatland forests are unique ecosystems, because of their extreme acidic, anaerobic and nutrient poor conditions. They support diverse forms of flora, fauna and microbes with many endemic and endangered species. In Central Kalimantan, peat fire has been a serious problem since the last decade. Peat fire is a major cause of peatland degradation that leads to loss of biodiversity and carbon stocks. In this study, we evaluated the impact of fire disturbance to forest structure and reforestation from the comparison among peatland forests with different disturbance severity. Results from current research revealed that (1) un-burnt forest maintained higher tree species diversity, larger basal area and trunk volume index than burnt forests, (2) once-burnt forest showed potential capacity of high recovery, (3) the forest affected fire showed significant floristic and structural changes and difficulty of recover.