Improving adoptability of farm forestry in the Philippine uplands: a linear programming model

In the Philippines, smallholder farmers have become major timber producers. But the systems of timber production practiced have several limitations. In intercropping systems, the practice of severe branch and/or root pruning reduces tree-crop competition and increases annual crop yields, but is detrimental to tree growth and incompatible with commercial timber production. In even-aged woodlots, lack of regular income and poor tree growth, resulting from farmers’ reluctance to thin their plantations, are major constraints to adoption and profitable tree farming. In the municipality of Claveria, Misamis Oriental, the recent practice of planting trees on widely spaced (6–8 m) contour grass strips established for soil conservation suggests ways to improve the adoptability (i.e., profitability, feasibility and acceptability) of timber-based agroforestry systems. Assuming that financial benefits are the main objective of timber tree farmers, we develop a simple linear programming (LP) model for the optimal allocation of land to monocropping and tree intercropping that maximizes the net present value of an infinite number of rotations and satisfies farmers’ resource constraints and regular income requirements. The application of the LP model to an average farmer in Claveria showed that cumulative additions of widely spaced tree hedgerows provides higher returns to land, and reduce the risk of agroforestry adoption by spreading over the years labour and capital investment costs and the economic benefits accruing to farmers from trees. Therefore, incremental planting of widely spaced tree hedgerows can make farm forestry more adoptable and thus benefit a larger number of resource-constrained farmers in their evolution towards more diverse and productive agroforestry systems.     

山西石楼县生态林业工程建设中的土地合理利用

根据区域生态经济学原理 ,结合晋西石楼县生态林业工程建设的实践 ,分析了县域土地资源利用现状 ,进行了土地利用多目标综合规划 ,阐述了生态林业工程土地合理利用的途径 ,并对其战略决策进行了分析。     

河南省林种结构调整的研究

根据１９９３年省森林资源清查、森林资源消耗量及消耗结构的调查资料，以可持续发展的理论为指导，采用线性规划对我省的林种结构进行了研究。研究结果：河南省现阶段的林种结构应为：用材林∶防护林∶经济林∶薪炭林∶特用林＝３４９∶１５９∶２３７∶２１１∶４４。     

Cutting technic forPinus elliottii plantation of the multi-benefit management pattern

The cutting technic for thePinus elliottii plantation of the multi-benefit management pattern in the hilly region of Jiangxi Province was studied by establishing the model of growth progress according to Richards function and simulating the tending cutting on computer by use of dynamic programming. The results showed that the best time for the initial thinning was at tree age of 8–10 and final cutting was at tree age of 25. The optimal thinning project was 3 times of thinning cutting including the first thinning, and the thinning time was at tree ages of 8, 12 and 16, respectively. Their thinning intensities were separately 950, 700 and 300 trunks per hectare, and the preserved density was 550 trunks per hectare until the final cutting Foundation item: This study was supported by Natural Science Foundation of Jiangxi Province (A grant 0330023) Biography: WANG Qing-chun (1970-), male, Ph. Doctor, Senior Engineer in Academy of Forest Inventory & Planning, Jiangxi, Nanchang 330046, P.R. China. Responsible editor: Song Funan     

Economic potential of agroforestry for public recreational parks

The availability of public recreational facilities is being threatened by growing demands, limited supplies, and declining government funding. In response to these pressures, the economic potential of agroforestry for supplementing operating budgets of public recreational parks is examined in a case study park consisting of 324 hectares. Agroforestry enterprises native to the area were selected for development on 70 hectares of the site. Linear programming was used to determine the optimum combinations of 23 agroforestry regimes composed of the following activities: 1) conventional forestry planting, tree density of 1682 trees/hectare, 2) the selected agroforestry planting with hay, tree density of 1495 trees/hectare, 3) the selected agroforestry planting with grazing, 4) hay production, and 5) rental of pasture for grazing. The objective function of the study was to maximize the net present value of the study site subject to land, labor, capital, and minimum annual income constraints. The preferred optimal regime generated $1782 per hectare from an agroforestry planting configuration of 1495 trees/hectare with 75 percent hay, 25 percent grazing, and no annual income requirements. Minimum annual income requirements of $2400 and $4800 were feasible but suboptimal from a net present value criteria. The study found that agroforestry could be used to privatize selective activities of public recreational parks and thus enable public agencies to provide these facilities more effectively.     

A mathematical model for generating land-use allocation alternatives for agroforestry systems

Agroforestry has been considered a viable land-use system particularly in the tropical regions. In developing or designing agroforestry systems, various concerns have to be addressed namely: (1) economic; (2) biological and physical; and (3) silvicultural and ecological considerations. This paper addresses these concerns from an interdisciplinary perspective. A land-use allocation model which ensures the simultaneous consideration of these concerns is proposed.     

Cost-efficient light control for production of two campanula species

A cost-efficient light control system based on weather forecasts, electricity prices and daily photosynthesis integral (DPI) was evaluated for application in the commercial production of the long-day (LD) plant Campanula portenschlagiana ‘Blue Get Mee’ and C. cochlearifolia ‘Blue Wonder’. Experiments were conducted under both autumn and spring conditions and included four treatments. Three treatments were controlled by the software system DynaLight Desktop which automatically defined the most cost-efficient use of supplemental light, -based on a predefined set point of DPI, forecasted solar irradiance and the market price on electricity. The set points of DPI in the three treatments were 300, 450 and 600 mmol CO₂ m⁻² leaf d⁻¹ and the treatments were compared with a traditional LD 19-h treatment. The DPI-based light control strategy resulted in very irregular light patterns including daily periods of solar irradiance combined with supplemental light in low light periods and a night period interrupted by irregular light breaks (NB-lighting). Both campanula species flowered in the DPI-based treatments during spring, but the flowering percentage was low and non-uniform during autumn. This was caused by a combination of the irregular light, low natural light intensities and a decrease in daily light integral (DLI), and could be restored by maintaining a continuous 19 h photoperiod with incandescent lamps (<5 μmol m⁻² s⁻¹), illustrating that photoperiod was an important factor for flowering in LD species grown under low light intensities. Growth in terms of carbon gain was marginally affected by the irregular light and a 25% reduction in electricity costs was achieved without major reductions in plant quality in spring. Our results illustrate that plant production of LD species can be maintained in a cost-efficient light control system where the use of supplemental light is based on weather forecasts and electricity prices.     

E－凸集的几个基本性质

利用比较与分析的方法，由E-凸集的定义出发，研究了E-凸集的若干基本性质．所得结果丰富并深化了凸分析的基本内容，拓宽了广义凸性在优化理论及其应用中的研究范围．     

Optimal utilisation of natural resources for agricultural sustainability in rainfed hill plateaus of Orissa

The climatic data for 17 years from 1988 to 2004 of the rainfed hill plateaus of Kandhamal district of Orissa (India) were analyzed to find out the monthly climatic index from the calculated values of effective rainfall and evapotranspiration. The 80% dependable monthly climatic index was correlated with crop coefficient and suitable cropping period and sequences for the study area were suggested based on it. The extent of investment, net return and soil loss from agriculture were estimated as per the present condition and for the suggested cropping patterns. A mathematical model was formulated for optimal allocation of area to different crop sequences with different objectives viz. minimization of soil loss, minimization of investment and maximization of net return from agriculture and was solved using linear goal programming technique. The model suggested to take up food crops in area of 1,30,777 ha and perennial grass cover in 3223 ha with a cropping intensity of 1.61 resulting in a net return of Rs 1064.775 millions sustaining soil loss to a tune of 9489.67 thousand tons per year. The model was found to be favourable in respect of higher net return of Rs 8862.34 and lesser soil loss of 23.41 tons/ha than the corresponding present values. But more investment of Rs 4489.01 per ha was required to fulfill the objectives.     

Optimizing competitive uses of water for irrigation and fisheries

Choosing the appropriate reservoir water management strategy can be difficult when the water has multiple uses. This study examines this problem for reservoir managers where water use involves irrigation and fisheries. A stochastic dynamic programming (SDP) model is developed to facilitate reservoir management, using a case study illustration for southern Vietnam. The model includes the response of rice and fish yields to key factors including reservoir water levels, the timing and quantity of water release, and climatic conditions. The model also accounts for variation in rainfall patterns, irrigation requirements, and the demand for low water levels during the fish harvest season. Three production scenarios are examined where the reservoir's water is used for: only producing rice (scenario 1), only producing fish (scenario 2), and producing rice and fish (scenario 3). Key findings are: (1) for scenario 1, adequate water should be released to meet rice growing water requirements and residual water should be stored as a source of water in case of low rainfall, (2) for scenario 2, sufficient water needs to be released prior to the fish harvest to maximize this harvest; and (3) for scenario 3, water should be released prior to fish harvest, but sufficient water should remain to satisfy the water requirements of rice. When the reservoir is managed for joint production of rice and fish, net benefits are 6% greater than when the reservoir is managed solely for rice production. The SDP model developed in this paper could be adapted and applied to other multiple-use resources such as forests, river basins, and land.