Phosphorus (P) is a limiting nutrient mined from non-renewable sources. P is needed to stimulate trees growth in a forest plantation. P-fertilizer addition in the tropical forest field causes P-leaching flux to watershed and induces eutrophication. The high C contained in meranti (Shorea sp.) biochar can avoid the P-leaching process in the soil with a strategic application method. However, the biochar application method is poorly examined. This research aimed to develop a biochar application method to sequestrate P from the environment and examine its effect on the growth of sengon (Falcataria moluccana). Shorea sp. biochar pyrolyzed at 400 °C and 600 °C were added at a dosage of 0 t ha⁻¹, 25 t ha⁻¹, and 50 t ha⁻¹ for six months in the field. The biochar was placed 20 cm under topsoil without soil mixing. This application method significantly increased total P in the soil without any P-fertilizer addition. The results showed that biochar pyrolyzed at 600 °C and a dosage of 25 t ha⁻¹ increased the total P in the soil and CEC by 192.2 mg kg⁻¹ and 25.98 me 100 g⁻¹, respectively. Biochar with a higher pyrolysis temperature increased higher soil pH. In contrast, the higher dosage increased organic-C higher than the lower dosage application. The most significant P-uptake, height, and diameter increments on F.moluccana were achieved using Shorea sp. biochar pyrolyzed at 600 °C with a dosage of 25 t ha⁻¹ by 0.42 mg kg⁻¹, 222 cm, and 2.75 cm, respectively. The total P in the soil positively correlated with the P-uptake of F. moluccana. Furthermore, using the biochar application method P could be absorbed to the biochar layer and desorbed to the topsoil. Consequently, the biochar application method together with P-fertilizer addition could increase the availability of P in the soil and decrease P-leaching to the environment.

Land cover changing would influence the availability of nutriens and others soil properties. In the forest areas, forest clearing would lead land degradation. KPHL Batutegi was catchment area for Batutegi dam. The ilegal logging that still occure in that area raising important question about the soil fertility status in that region. Its related to soil capability to the plant growth. The aims of this study was to get information about soil fertility status in two type of land cover, which was secondary forest and one year mixed coffee plantation. Soil sample was taking by purpose sampling on two type of land cover in KPHL Batutegi. One year mixed coffee plantation opened by illegal loging with fired. Intact soil samples were taken using the ring samples, while for the disturbed soil was done by the composite. Parameters observed were nutrients contain (N, P, and C-organic), pH, CEC, soil thickness, total pores and textur. The result showed that there no different on nutrient status and chemical soil properties between two land cover type. It was important from this study obtained that about 10 cm soil lost after one year land clearing from secondary forest to mixed coffee plantation.

The use of mercury in gold refining causes air pollution and results in the contamination of multipurpose tree species (MPTS). Tree bark has properties that cause it to store mercury for quite a long time. The purpose of this study was to determine mercury contamination of MPTS and map the mercury contamination distribution in the atmosphere using tree barks as bioindicators. Sampling was performed using purposive sampling. The mercury concentration was obtained by atomic absorption spectroscopy, and the highest THg contents were analyzed using a scanning electron microscope. The analysis was carried out by gauging total mercury (THg), distance, elevation to THg, and interpolation of THg at the research site. The results showed that there were 10 types of MPTS trees whose bark could accumulate mercury. The bark of the Tamarindus indica tree stored the greatest amount of THg (74.4 µg dry weight (DW)), followed by Persea americana (58.7 µg DW), and Annona muricata (44.2 µg DW), respectively. This result was influenced by the roughness of the bark and the location of the plants. No correlation was found between distance and elevation to THg on tree bark. The mercury interpolation in the atmosphere showed that mercury moves from the purification point to the southeast of the purification location.

Mercury (Hg) is a useful heavy metal; however, it is toxic to both humans and the environment. Tree bark is an excellent bioindicator, which has been proven to be effective in studying the level of atmospheric Hg contamination. This study aimed to determine the distribution of evaporated Hg using the total weight of Hg (THg) in tree barks in Indonesia at the artisanal and small-scale gold mining (ASGM) area of Bunut Seberang Village and Lampung University, respectively. Samples were taken using purposive sampling, based on the criteria of forestry trees at a height level of 1.3 m above ground as wide as 100 cm². The samples were analyzed by atomic absorption spectrometry and Scanning electron microscopy to determine the levels of THg and to investigate the bark structures. Results showed that the highest THg values were found in a Magnolia champaca sample (56.5 µg), followed by Swietenia mahagoni (45.8 µg) and Swietenia mahagoni (33.5 µg). All species studied showed THg levels in the tree barks at an elevation from 30 to 320 m above sea level. The Hg amounts found in the sampled barks indicated the dispersion of Hg throughout the ASGM area, which signified hazardous atmospheric conditions in the area.

Imperata cylindrica is an aggressive and difficult-to-control weed in production forest areas. The use of plant-based bioherbicides offers an environmentally friendly alternative to reduce reliance on synthetic herbicides. This study aims to evaluate the effectiveness of extracts from Filicium decipiens and Swietenia macrophylla in suppressing the growth of weeds. The study was conducted using a Competly Randomized Design with five treatments: control, 25% and 50% F. decipiens extract, and 25% and 50% mahogany extract, and replicated 5 times. The parameters observed included changes in leaf color, survival rate, root length and diameter. The results showed that the 50% F. decipiens extract was most effective in reducing root diameter and plant survival rate (only 20% survived), while the 50% mahogany extract most effectively inhibited root length. The browning of leaves indicated tissue damage caused by phenolic compounds, flavonoids, and saponins. This study demonstrated that F. decipiens leaf and mahogany extracts have potential as effective and environmentally friendly bioherbicides for controlling sedge weeds.

This study explores the effects of pyrolysis temperature of shorea wood biochar and its doses on the soil properties and biomass of Falcataria moluccana seedlings. The focus is optimizing pyrolysis temperatures (400°C and 600°C) and biochar doses (0%, 25%, and 50%) to enhance soil fertility and seedling biomass. Both pyrolysis temperature and biochar dose are critical factors that influence the soil properties, directly affecting its effectiveness as a soil amendment. The research was conducted as a controlled greenhouse experiment over 120 days; each treatment was replicated 15 times. We observed several soil chemical properties, including pH, cation exchange capacity (CEC), organic carbon (C-organic), total nitrogen (N-total), and total phosphorus (P-total). The growth parameters assessed included above ground biomass (AGB), below ground biomass (BGB), total biomass (TB), and root to shoot ratio (R:S). Data analysis involved one-way and two-way ANOVA. Results indicated that soil properties, particularly cation exchange capacity (CEC) and organic carbon content, were improved, thereby enhancing soil fertility. However, ANOVA indicated no statistically significant differences across treatments. Biochar significantly enhanced above-ground and below-ground biomass (AGB and BGB). Nevertheless, both pyrolysis temperature and biochar dose independently influenced biomass accumulation in F. moluccana seedlings. The highest increases were observed in the treatment with the highest pyrolysis temperature (600ᵒC) and the highest dose (50%), which led to an 85% increase in AGB and a 60% increase in BGB compared to the control. Based on the study, Shorea wood biochar, particularly when used at 600°C and 50% dose, significantly improves soil fertility and seedling growth, providing a promising approach for developing F. moluccana plantations.