Deal with disconnects between equations that switch when trees cross a size threshhold

[teixeirak]

The database will allow application of different equations to trees of different size (e.g., switch from a highly specific allometry for small sizes to a more generic one at sizes above that sampled for the specific one). This is desirable. However, when a tree crosses a size threshold, estimates of woody growth and ANPP will be seriously flawed. To address this, we need to incorporate code that forces the application of only one allometric equation-- even outside its range--to trees that grow over such a threshhold.

[teixeirak]

This will apply more to "wrapper" code than to allodb.

When looking at changes in biomass, we should track the allometry ID that is applied to each individual. If the allometry ID changes from one census to the next, we need to go back and calculate biomass using a consistent allometry, even if (slightly) outside the range for which an allometry was developed. When there's an equal number of records before and after the tree crossed a threshold, err on the side of using the allometry for larger diameters, as the tree will continue to grow (plus this should introduce less error).

[teixeirak]

In cases where we transition from one equation to another as tree size increases, we should select the equation based where the lines cross rather than the min/max DBH associated to each allometry. For instance, for Liriodendron, small trees are described by a function that accelerates rapidly with DBH, and larger trees by a more gradual function. Based on the min/max diameters for each equation, trees would grow and then shrink by quite a bit when you transition to the new equation. Rather than allow this, we should switch to the large tree equation when the small-tree equation gets above what it would predict. (Sorry, I didn't save the plot showing this example, but it would be easy to reconstruct.)

[gonzalezeb]

Closing issue. This was solve with the weighting system.