Forest

Emulates a natural forest growth: seed dispersal, the growth of trees, the adequacy of lighting, and soil quality. Forest Generator can generate several forests of one tree type. As forests grow and expand they will be joint together into a single whole. Each forest starts with a single tree - a seedling.

Along with Erosion Generator this Generator takes some time to compute. Keep in mind that a forest is a system with negative feedback. Every little change in the beginning causes an absolutely different result in the end. So generating a forest with slightly different inputs can cause a very different final picture. For example, changing the seedling’s position can cause the entire forest to die, while other forest arrays would appear in different places.

Inputs:

Seedlings - the initial trees. Each of the seedlings starts a new forest.
Other Trees - additional objects that shade the trees. For example, when planting a birch forest it could be more long-lived trees like oaks. This object hash prevents the forest from growing in the other forest’s area.
Soil - a map that controls the chance of the tree to live and to produce seeds. Poor quality (low map values) raises the tree’s chances of dying. Think of it like soil quality but this also could be a height or slope factor or their multiplication. This parameter can control not only the soil quality, but other aspects like height or slope factor.

Properties:

Years: number of years passed since the first seedling started to grow. In most cases this parameter determines the size of the forest, but in some cases the forest can shrink after it matures and even die - this often happens for tall trees (i.e. high Shade Dist value) and poor soil.

Years: 15, 30, 50, 100, 150
Density: the maximum number of trees in an area of 1 square kilometer (in world units). This value is equivalent to the Scatter density parameter.

Density: 5000, 10000, 15000
Fecundity: how many seedlings the tree produces per year. The more the value the faster the forest spreads.

Fecundity: 0.1, 0.2, 0.5, 0.8

As well as Years parameter this value sets the forest size. However Years determine iterational forest size, while Fecundity sets the number of trees created per iteration. Using Fecundity over Years result in more younger trees growing in less suitable conditions.
Seed Dist: how far a tree can throw a seed (in world units). Increasing this parameter can make a forest spread fast, but less predictable. Larger values can make seeds travel over the areas with inappropriate soil (like cliffs or rivers), spreading forests over natural obstacles.

Increasing this value while Fecundity is low will make the forest less dense since all of the seedlings are spread extensively.

Seed Dist (Fecundity 0.2): 5, 15, 30, 50
Reproductive Age: the age at which the tree starts to produce seedlings around it.
Survival Rate: a chance for the tree to survive each year. This value is multiplied with a Soil Mask.
Max Age: the maximum tree life time. The tree will die when it reaches this age, but it can die earlier because of bad conditions (i.e. Survival Rate).
Size is Age: will set the output object size (scale) factor to the tree age, in years.

If enabled, the age of each tree in a Tree’s output is recorded as an object size. One year corresponds to 1 unit in size: the first year’s sapling’s size would be 1, while a hundred year old tree’s size would be 100. Use Split Generator to sort trees, with the conditions properly set: for example for young trees the Size Condition should be 0-10, for medium trees 10-30, for big ones 30-200.

Note that most of the trees will have a scale over 1, use adjust generator to modify it or disable Scale in trees output.