Leverage climate-cheatgrass abundance relationships in Brummer et al. 2016 to scale cheatgrass input parameters

[kpalmqui]

• allow input parameters for cheatgrass (BRTE) to vary across sties based on the climate-abundance relationships presented in Brummer et al. 2016:

BRTE abundance ~ July precipitation + Temperature of the driest quarter

• identify these two aspects of climate for each site and scale necessary parameters according after testing is complete in issue Additional testing of var, pestab, and eind needed due to overhaul of how alpha and beta are calculated in establishment for annual species #115

[kpalmqui]

This issue has been implemented and partially resolved in rSFSTEP2. Cheatgrass space is now scaled according to July Precipitation and minimum temperature in February. See issues:

DrylandEcology/rSFSTEP2#56
DrylandEcology/rSFSTEP2#54
DrylandEcology/rSFSTEP2#55
DrylandEcology/rSFSTEP2#106

There is currently no on-the-fly scaling of other cheatgrass parameters (i.e. eind, pestab, var, pseed). That may be warranted in the future, but for the time being I am going to close this issue.

We have another open issue within STEPWAT2 involving testing of pestab, eind, var, and pseed for cheatgrass to determine a reasonable set of parameters to utilize for sites in the meantime. #115