Sarminah S, Karyati, Karmini, Simbolon J, Tambunan E. 2018. Rehabilitation and soil conservation of degraded land using sengon (Falcataria moluccana) and peanut (Arachis hypogaea) agroforestry system. Biodiversitas 19: 222-228. Rehabilitation and soil conservation effort on degraded lands is not always a success. Multiple factors, such as the field’ biogeophysical conditions and the choice of suitable plant species determine the effectivity of the rehabilitation program. Our research aimed to implement agroforestry system of sengon (Falcataria moluccana) and peanut (Arachis hypogaea) on degraded land at different soil slopes (a steep and a slightly steep slope gradient) and to analyze the effect of the system on silvicultural and hydro-orological aspects of the degraded land. The silvicultural parameters examined in this study were the ground coverage of peanut growth and the stem diameter and height of sengon trees. Meanwhile, the hydro-orological parameters included potential erosion rate, erosion hazard index, and erosion hazard level. Our study revealed that on the land with the slightly steep slope (15-25%), the survival rate of sengon reached 90%, the ground coverage of the peanuts was 70-80%, the diameter and height increment of sengon trees reached 2.47 cm/year and 17.58 cm/year, respectively. Meanwhile, the potential erosion rate was 20.05 ton/ha/year, with an erosion hazard index of 0.80 (low) and a low hazard level. In the steeper ground (25-40%), the survival rate of sengon reached 90%, the peanut coverage was 50-60% and the diameter and height increment of the sengon were 2.37 cm/year and 16.41 cm/year, respectively. In the steep ground, potential erosion rate was 45.50 ton/ha/year, with an erosion hazard index of 3.25 (moderate) and a low hazard level. We concluded that the rehabilitation and soil conservation using sengon-peanut agroforestry system effectively suppressed erosion rate to a low erosion hazard.

There is a large area of abandoned land that is not taken manage of after plantation activities in the tropic. These abandoned gardens which have been neglected for a long time have important ecological and economic values. This study aims to assess the existence of abandoned land in the tropic from an ecological and economic perspective. The ecological aspects assessed were stand structure, floristic composition, and species diversity. Meanwhile, the economic aspects analyzed were log price, harvesting cost, profit margin, and stumpage value. The vegetation survey was carried out on all woody trees with a diameter at bresst height (DBH) > 5 cm in 10 subplots each sized 20 m × 20 m. A total of.192 trees were recorded of 29 species belonging to 19 genera and 17 families. The most dominant species were Macaranga triloba (Importance Value, IV of 46.16), Macaranga tanarius (IV of 22.97), and Nephelium lappaceum (IV of 20.94). The indexes of diversity, dominance, evenness, and richness in the studied plots were 1.33, 0.06, 0.40, and 5.33, respectively. The means of wood price, logging cost, profit margin, and stumpage value at abandoned land were USD199.55 m-3, USD69.01 m-3, USD25.45 m-3, and USD51.56 ha-1, respectively. The abandoned lands with high ecological and economic value indicate the important role of abandoned lands in the secondary succession process in the tropics.

Abstract. Karmini, Sarminah S, Karyati. 2017

The floristic structure and composition of abandoned lands in the tropic have been observed to be changing dynamically during the succession process. This is mostly because they are not utilized maximally, therefore, there is a need to assess the economic and ecological impacts of this land abandonment in tropical areas. This study was conducted to determine the ecological aspects of standstructure, floristic composition, and species diversity and analyze the economic aspects of standing trees in tropical abandoned land. The vegetation containing woody trees with a diameter at breast height (DBH) of > 5 cm were surveyed at six subplots sized 20 m × 20 m. The economic parameters were evaluated using data of log price, logging cost, profit margin, and stumpage value of standing trees in the study plot and a total of 126 trees including 26 species of 25 genera of 18 families were recorded. The most common species found were Macaranga tanarius with 50.60%, Bridelia glauca with 49.13%, and Pterospermum javanicum with 29.05% based on Importance Value Index (IVi). Moreover, the diversity, dominance, evenness, and richness indices were 1.23, 0.09, 0.87, and 5.17 respectively while the total log price at the abandoned land was 1,462.02 USD m-3 with an average value of 56.23USD m-3. The total and mean values of logging costs were 1,212.24USD ha-1 and 46.62USD ha-1, respectively while the total profit margin of log selling was USD337.39m-3 at maximum with an average of 12.98 USD m-3. Furthermore, the average stumpage value was 83.05 USD ha-1 while the total was calculated to be 2,159.36 USD ha-1.These findings showed the utilization of abandoned lands with respect to ecology and economic aspects has the ability to increase community welfare and support the implementation of developmental programs in the country.

Abstract. Karyati, Widiati KY, Karmini, Mulyadi R. 2021. The allometric relationships for estimating aboveground biomass and carbon stock in an abandoned traditional garden in East Kalimantan, Indonesia. Biodiversitas 22: 751-762. The existence of traditional gardens after abandonment process has a role based on ecological and economic aspects. To estimate the biomass and carbon stock in the abandoned traditional gardens, specific allometric equations are required. The aim of this study was to develop allometric equations to estimate biomass of plant parts (leaf, branch, trunk, and aboveground biomass (AGB)) through tree dimensions variables (diameter at breast height (DBH), total tree height, and tree bole height). The relationships between stem biomass, AGB and tree dimensions were very strong indicated by the relatively high adjusted R2 value. The moderately strong relationships were shown between branch biomass and tree dimensions, meanwhile, the relationship between leaf biomass and tree dimensions was very weak. The specific allometric equations for estimating biomass and carbon stocks that are suitable for tree species and/or forest stands at a particular site are very useful for calculating the carbon stocks and sequestration. The appropriate biomass and carbon stock calculation are needed to determine policies related to global climate change.