The Full Lands INtegration Tool aka FLINT is the flagship software of moja global. FLINT’s niche is managing and providing useful insights about existing data, offering great flexibility with respect to the method in which inputs are provided and outputs are required. The GCBM, an adaptation of the FLINT uses growth-and-yield curves that describe the relationship between stand age and stand volume. A stand or forest stand refers to a group of trees with similar characteristics in an area.
Through this blog, I will explain my understanding of growth and yield curves.
The Yield of a forest can be defined as the volume of useful wood fiber/timber per unit area. It is most commonly observed that the yield increases at an increasing rate up to a point, after which it decreases at a decreasing rate.
Site Index is a term often used when referring to yield curves. Site index is a term used in forestry to describe the potential for forest trees to grow at a particular location or “site”. Eg: If it is stated that the site index for a Neem tree is 30m at 50 years, it means that a Neem tree planted today in a particular site will be at a height of 30m, 50 years later. “Index” years, like 25, 50, 100 are used for references. For values other than those, an interpolation can be done. It can be observed that a greater site index will mean a greater yield. i.e a greater height tree will yield a higher amount of timber
Description of the image: Site index curves for loblolly pine at index age 50 years in the Coastal Plain of Virginia, North Carolina, and South Carolina. (These curves are based on stem analysis of 40 dominant trees in the middle and lower Coastal Plain.)
Growth can be interpreted as the rate of yield, the way in which the yield changes influences the growth curve. There are variants in how the growth is expressed, such as Annual Increment, Periodic Annual Increment, Compound Interest Rate, Mean Annual Increment, etc. To quote an example of Annual Increment:
Annual Increment = Yield(T) — Yield(T-1), where T-1 and T are consecutive years
Factors affecting yield and growth
- Species of trees/plants growing in an area
- Age of the trees/plants
- Weather and soil conditions and nutrition
- Wildlife, biodiversity in the landscape
- Competition amongst the different species for resources (survival of the fittest, does it ring a bell ?)
This information is important to understand the changes to a landscape, identify trends, devise mitigation measures in case of pests/natural calamities, and aid the government bodies taking decisions relating to forests