Forest Growth Rate Calculator
Our forest carbon sink calculator computes forest growth rate accurately. Enter measurements for results with formulas and error analysis.
Formula
CAGR = (Final/Initial)^(1/Years) - 1
CAGR = (Final/Initial)^(1/years)-1. Absolute = (Final-Initial)/Years. MAI = biomass/age. Gross adds mortality. Doubling = ln2/ln(1+rate).
Worked Examples
Example 1: Temperate Forest
Problem: 50 ha forest: 120 t/ha (2010) to 185 t/ha (2020), mortality 1.5%/yr.
Solution: Absolute = 6.50 t/ha/yr\nCAGR = 4.42%/yr\nMAI = 18.50\nGross = 8.30\nNet = 3,250 t\nCO2e = 560 t/yr\nDoubling = 16 yr
Result: CAGR = 4.42% | 6.50 t/ha/yr | 560 t CO2e/yr
Example 2: Eucalyptus Plantation
Problem: 200 ha: 30 to 110 t/ha over 5 yr, mortality 0.5%.
Solution: Absolute = 16 t/ha/yr\nCAGR = 29.65%\nNet = 16,000 t\nCO2e = 5,513 t/yr\nDoubling = 2.7 yr
Result: CAGR = 29.65% | 16 t/ha/yr | 5,513 t CO2e/yr
Frequently Asked Questions
What is forest growth rate?
Forest growth rate measures how quickly forest biomass increases over time, expressed as an absolute rate (tonnes per hectare per year) or relative rate (percentage per year). The absolute growth rate is the difference between final and initial biomass divided by the time period. The compound annual growth rate uses the formula CAGR = (final/initial)^(1/years) - 1. Growth rates vary by forest type, age, climate, and soil, ranging from 1-3 t/ha/yr in boreal forests to 15-30 t/ha/yr in tropical plantations.
How does forest age affect growth rate?
Forest growth follows a characteristic sigmoid curve. Young forests grow slowly as seedlings establish, then enter a rapid growth phase with high PAI as trees compete for light and close canopy. Growth then gradually declines as trees reach maximum size and respiration costs increase. Old-growth forests may have near-zero net growth as new biomass roughly equals mortality losses. The age of peak PAI varies by species, occurring at 10-15 years for eucalyptus but 40-80 years for slow-growing hardwoods like oak.
What is gross growth versus net growth?
Gross growth is the total biomass added by all living trees through photosynthesis during a period. Net growth is gross growth minus losses from tree mortality, branch fall, and decomposition. In young healthy forests, mortality might be only 1-2 percent per year, so net growth is close to gross growth. In mature forests, mortality can consume 50 percent or more of gross growth. Understanding both metrics is essential for accurate carbon accounting and sustainable forest management.
How do you measure forest biomass change over time?
Forest biomass change is measured through repeated forest inventories using permanent sample plots. At each visit, diameter at breast height, height, and species of each tree are recorded. Allometric equations convert measurements to biomass estimates. The difference between successive measurements gives the growth increment. National Forest Inventories typically revisit plots every 5-10 years. Remote sensing supplements ground data, with LiDAR providing precise canopy height models that correlate with biomass.
What factors control forest growth rate?
Growth is controlled by climate (temperature, precipitation, season length), soil (nutrients, depth, drainage), stand factors (species, age, density), and disturbance history. CO2 fertilization has increased growth 10-30 percent since pre-industrial times. Managed forests with thinning grow 20-50 percent faster than unmanaged natural forests of similar type and age.
What is the doubling time for forest biomass?
Doubling time equals ln(2) divided by ln(1 + r) where r is annual growth rate as a decimal. A forest growing at 5 percent doubles in about 14 years, while 2 percent growth takes 35 years. Fast-growing plantations can double in 5-8 years. Doubling time is useful for comparing carbon sequestration potential of different reforestation strategies across species and regions.