deadwood calculations

[jo-tham]

for wildfire and habitat

@juliannosambatti and @jo-tham to to touch base with @ianmoss to define the requirements and discuss implementation for this

[juliannosambatti]

Questions:
Do we have a model that we want to follow?
Ex in a discrete variation.

Number_of_dead_trees (t) = number_of_dying_trees - number_of_dead_trees*rate_of_decay

number_of_dying_trees(t) = number_of_trees (t) - number_of_trees(t-1)

rate_of_decay = f(species, diameter, gross_volume, site)

---

VolumeDeatTree (t) = volume_of_dying_trees - Volume_of_dead_trees*rate_of_decay

volume_of_dying_trees -> must assume something as for example:

1. all dying trees have the same volume and so the volume of dying trees is the proportion of trees dying from a year to another. The question is which is the volume (mean volume?)

2. Death rate is the same across tree diameter distribution and along time. This is another way to see 1 when using mean volume.

3. Death rate is higher in known parts of the diameter distribution. This is more realistic, but requires estimation of many parameters, such as: diameter distribution, death rate per diameter class at any particular age.

---

Strategy:
I prefer the accountability of dead wood volume. Sum the volume arriving at the dead_wood box every year and discounting the decay rate every year.

[jo-tham]

I support your strategy @juliannosambatti (accounting dead wood volume)

Especially to keep it simple for now (ignoring the death rate variability in diameter distribution). We can always revise it later if necessary.

Lets touch base with @ianmoss before going ahead.

After that we can consider how we'd like to implement this function and integrate into the high level function