Afforestation Site Suitability Calculator
Compute afforestation site suitability using validated scientific equations. See step-by-step derivations, unit analysis, and reference values.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Suitability Score = Sum(Parameter Score x Weight) for all parameters
Each environmental parameter is scored 0-100 based on optimal ranges for tree growth, then multiplied by its relative weight. Rainfall (25%), soil depth (15%), slope (15%), temperature (15%), soil pH (10%), altitude (10%), solar radiation (5%), and water proximity (5%) are combined into an overall suitability index.
Worked Examples
Example 1: Temperate Highland Afforestation Assessment
Problem:Assess suitability of a site with 900mm rainfall, 1.2m soil depth, pH 6.2, 12% slope, 700m altitude, mean temperature 14C, 200 W/m2 solar radiation, and 1.5km from nearest stream.
Solution:Rainfall score (900mm optimal range): 95\nSoil depth score (1.2m adequate): 60\npH score (6.2 near optimal): 93\nSlope score (12% gentle): 82\nAltitude score (700m favorable): 97\nTemperature score (14C temperate): 88\nSolar score (200 W/m2): 80\nWater score (1.5km close): 95\n\nWeighted total = 95x0.25 + 60x0.15 + 93x0.1 + 82x0.15 + 97x0.1 + 88x0.15 + 80x0.05 + 95x0.05 = 86.4
Result:Overall Score: 86.4 (Highly Suitable) | Recommended: Oak, Pine, Birch | Growth rate: ~8.6 m3/ha/yr
Example 2: Semi-Arid Lowland Site Evaluation
Problem:Evaluate a site with 350mm rainfall, 0.8m soil depth, pH 8.2, 5% slope, 200m altitude, mean temperature 22C, 250 W/m2 solar radiation, and 8km from water.
Solution:Rainfall score (350mm very low): 35\nSoil depth score (0.8m moderate): 40\npH score (8.2 alkaline stress): 58\nSlope score (5% flat): 93\nAltitude score (200m low): 82\nTemperature score (22C warm): 88\nSolar score (250 W/m2): 100\nWater score (8km far): 45\n\nWeighted total = 35x0.25 + 40x0.15 + 58x0.1 + 93x0.15 + 82x0.1 + 88x0.15 + 100x0.05 + 45x0.05 = 63.2
Result:Overall Score: 63.2 (Moderately Suitable) | Recommended: Drought-resistant, Prosopis, Tamarix | Growth: ~4.2 m3/ha/yr
Frequently Asked Questions
What is afforestation and how does it differ from reforestation?
Afforestation is the establishment of a forest on land that has not been forested for a long period or has never been forested, such as converting grassland or agricultural land to forest. Reforestation, by contrast, involves replanting trees on land that was recently forested but lost its tree cover due to harvesting, fire, or disease. This distinction is important for carbon credit programs because afforestation creates new carbon sinks that did not previously exist, while reforestation restores lost ones. Under the Kyoto Protocol and Paris Agreement, afforestation projects receive specific accounting treatment. The IPCC defines the minimum qualifying period without forest as typically 20 to 50 years depending on national definitions.
What are the most important factors for afforestation site selection?
The most critical factors for afforestation site selection include annual rainfall, soil depth and quality, topographic slope, and mean temperature. Rainfall determines water availability for tree establishment and growth, with most temperate species requiring at least 600 millimeters annually. Soil depth must be sufficient for root development, typically at least 50 centimeters for adequate tree growth. Slope affects soil erosion risk, planting feasibility, and water retention. Temperature influences species selection and growth rates. Secondary factors include soil pH, solar radiation, proximity to water sources, wind exposure, and existing land use. Successful afforestation requires matching these site conditions to appropriate tree species.
How does soil pH affect tree growth in afforestation projects?
Soil pH profoundly affects nutrient availability and tree growth. Most forest tree species grow best in slightly acidic to neutral soils with pH between 5.5 and 7.5. At pH below 4.5, toxic concentrations of aluminum and manganese can damage roots, while essential nutrients like phosphorus, calcium, and magnesium become unavailable. Above pH 8, iron, manganese, and zinc deficiencies commonly limit growth. Some species have evolved tolerance for extreme pH values, such as blueberry and rhododendron in acidic soils, or mesquite and certain eucalyptus in alkaline conditions. Soil amendments like lime or sulfur can modify pH, but this is often impractical at the scale of afforestation projects.
How does slope and terrain affect afforestation success?
Slope gradient significantly impacts afforestation through effects on soil erosion, water retention, mechanization feasibility, and microclimate. Slopes under 15 percent are generally ideal for afforestation, allowing machine planting and minimal erosion risk. Slopes between 15 and 30 percent require contour planting techniques and erosion control measures. Above 30 percent, planting becomes labor-intensive and erosion risk is severe without engineered terrace systems. Aspect also matters in the northern hemisphere, where south-facing slopes receive more solar radiation and are warmer and drier, favoring drought-tolerant species, while north-facing slopes are cooler and moister, supporting shade-tolerant species.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy