Acacia Mangium Willd. is one of the most important tree species grown in commercial plantation in Monsoon Asia. Recently, the need for accurate information in the biomass in plantations has become more urgent, especially since the amount of carbon sequestered in afforestation/reforestation Clean Development Mechanism (AR-CDM) projects in developing countries can be included under the Kyoto Protocol. We present here a general allometric equation for estimating aboveground biomass (AGB) of A. mangium plantations from the diameter of the trees recorded at the respectives sites. Destructive samplings were conducted in Papua New Guinea, Vietnam, and Indonesia. At each site, 4-12 trees were felled, their trunks, branches and leaves were separately weighed, and allometric models for estimating AGB was determined. A general allometric equation (A log-log model) was developed from an overall total of 26 sample trees from sampled sites. No significant differences were found between the biomass estimations derived from the site-specific and the general allometric equations. The general allometric equation may allow us to estimate AGB of A. mangium plantations in Monsoon Asia without destructive sampling.
Tag: acacia mangium
Acacia mangium plantations in PT Musi Hutan Persada, South Sumatera, Indonesia
PT Musi Hutan Persada, a forestry company growing wood for pulp in South Sumatra manages about 200 000 ha of forest plantations, 90% of which consists of Acacia mangium. Most of the plantations are in an area with high rainfall and on red-yellow podzolic soil with inherently poor fertility and low pH. Inter-rotation site productivity and management have been identified by the company as one of the crucial issues for sustaining the long-term productivity of its plantations. This paper describes the study plan for inter-rotation site productivity and management of A. mangium plantations in PT Musi Hutan Persada. The experiment tests the on-site effect of different treatments of organic matter or aboveground biomass management. Information from earlier work indicates that most A. mangium biomass and three major nutrients (N, P and K) is in the wood, and harvesting will remove around 200 kg N, 45 kg P and 240 kg K per hectare. Litter production of an 8-year old stand was about 13 t ha -1 and about 70% of its mass will be lost in one year.
Agroforestry approaches or rehabilitating degraded lands after tropical deforestation
There are three main types of degraded lands that result from slash and burn agriculture: degraded fallows, degraded pastures and Imperata cylindrica grasslands. Together they may cover as much as 250 million hectares, and have the advantage for recuperation of being close to road, market and urban infrastructure. Land degradation can be due to one or more causes: physical (e.g. soil compaction, erosion), chemical (e.g. increases in soil acidity, decline in available nutrients) and biological degradation (e.g. loss of microsymbionts, weed encroachment). The use of bulldozers to clear land accelerates degradation and generally requires more labour, energy and/or purchased inputs for reclamation. The current research knowledge base has focused upon alternatives to slash and burn that start with fertile, cleared forests rather than degraded systems. In the past, agroforestry approached for reclaiming the three types of degraded systems. Int he past, agroforestry approaches for reclaiming the three types of degraded lands were employed but most of the experiences are not based on sound research. The establishment of Acacia mangium on Imperata grasslands is one success story. In the case of degraded fallows and pastures, land regeneration strategies have been identified (e.g. economically and biologically improved fallows; silvopastoral systems) but the essential research is still to be done. Fundamental concepts of restoration ecology with emphasis on nutrient cycling, plant succession and weed dynamics should set the state for understanding how to turn degraded areas into productive lands. Coupled with appropriate policies and other socio-economic considerations, such work will provide viable alternatives to land abandonment after tropical deforestation.
A manual of diseases of tropical acacias in Australia, Southeast Asia and India
Acacias are of considerable social and industrial importance for tropical reforestation, with about 2 million ha worldwide. The last few decades have seen a major expansion of plantations for industrial use, especially in South-East Asia. Both native and exotic species of Acacia are also widely grown in the Indian sub-continent. Turnbull et al. (1998) reviewed the status of tropical acacia plantations in Asia. The species which have been most widely planted so far in industrial plantations in South-East Asia are Acacia mangium Willd. and A. auriculiformis Cunn. ex Benth. A. crassicarpa Cunn. ex Benth. and A. aulacocarpa Cunn. ex Benth. provenance and species trials have been established in many locations throughout the region to provide options for future hardwood plantations. Commercial plantings of A. crassicarpa have recently been established in Indonesia. Plantations of acacias in the humid tropics have been relatively free of disease compared to eucalypts that are commonly damaged by disease in such environments. Reports from several countries in South-East Asia and northern Australia have, however, suggested that the future productivity of acacia plantations may be affected by fungal pathogens. During 1995–96, surveys of diseases of the four Acacia species mentioned above were carried out in northern Australia and several countries of South-East Asia, supported by funding from the Australian Centre for International Agricultural Research (ACIAR) and the Center for International Forestry Research (CIFOR). The surveys by forest pathologists were undertaken in native stands, trials and industrial and social forestry plantations of tropical acacias in Australia, India, Indonesia, Malaysia and Thailand. The objectives were to assess the potential of fungal pathogens as limiting factors to tree growth and productivity, and to compare the relative importance of individual fungal pathogens.
Agroforestry: contribution to food security and climate-change adaptation and mitigation in Southeast Asia.
Agroforestry, the practice of using trees on farms, and the integration of forestry and agriculture as part of multifunctional landscapes, can provide multiple economic, social and environmental benefits. In a global comparison, Southeast Asia had the highest biomass carbon stock (per hectare) on agricultural land of all regions, with an increasing trend (60 tonnes of carbon per hectare in 2000 and 65 tonnes per hectare in 2010). Farmers in different parts of the region have been adopting diverse agroforestry systems and practices, increasing the productivity of farmlands, and helping to secure food, income and other basic needs. At the same time, the significant amount of carbon sequestered by trees in agroforestry systems is contributing to climate-change mitigation, while forests and trees are ‘air conditioners’ cooling their surroundings by bringing water back into the atmosphere. Yet, wide-scale agroforestry adoption remains limited due to many obstacles and challenges, notably, the lack of institutional home and specific policy support for agroforestry.
Biological Water Quality Indicators in Upland Catchments: Family Biotic Index as an Assessment Tool
Forest conversion to agriculture such as coffee garden and rice field rapidly occured in the upper Way Besai watershed, Sumberjaya, Lampung, Indonesia which invo lved activities such as land clearing, soil tillage, planting, weeding and applying fertilizers and pest icides by farmers. Those activities affect the water quality along t he stream and river through sedimentation and accumulation of nutrients and pesticide residues.
Biomass equations for tropical tree plantation species using secondary data from the Philippines
Estimation of the magnitude of sinks and source s of carbon requires reliable estimates of the biomass of forests and of individual trees. Equations for predicting tree biomass have been developed using secondary data involving destructive sampling in plantations in several localities in the Philippines. These equations allow estimates of carbon sequestration to be made at much lower cost than would be incurred if detailed stand inventories were undertaken. The species included in the study reported here include Gmelina arborea, Paraserianthes falcataria, Swietenia macrophylla and Dipterocarp species in Mindanao;Leucaena leucocephala from Laguna, Antique, Cebu, Iloilo, Rizal, and Ilocos Sur, and Acacia mangium, Acacia auriculifor mis and G. arborea in Leyte. Non-linear regression was used to derive species-specific, site-specific and generic equations between yield and diameter of the form y = aDb . Equations were evaluated based on the correlation co efficient, standard error of the estimate and residual plots. Regressions result ed to high r values (>0.90). In some cases, non-homogeneous variance was encountered. The generic equation improved estimates compared with models used in previous studies.
Imperata economics and policy
Should policymakers — or anyone else — care about millions of ha of Imperata grasslands The answer depends on the balance between costs of conversion to other uses and the net benefits produced in economic growth, poverty alleviation, and protection of the environment. The first section on Imperata economics sets up the analytical framework to address this question and draws on the wider development economics literature to consider whether growth and poverty alleviation are conflicting or complementary objectives. Although evidence is limited, it suggests smallholder-based agroforestry could provide the same economic growth with greater poverty alleviation than large-scale forestry estates. There is, however, no substitute for project appraisal for specific settings. The second section on Imperata policy reviews whether policy distortions and market failures provide a sufficient rationale for direct policy intervention to promote tree planting on Imperata grasslands. Estimates of imputed values of carbon sequestration to alleviate global warming are presented for Acacia mangium and rubber agroforestry. The conclusion summarizes the policy research agenda and examines the desirability and feasibility of policy intervention to promote carbon sequestration through Imperata grassland conversion to tree-based systems.