Methods
To create this map, existing Soil Survey Geographi Database
(SSURGO) soil map units were sub-divided based on imagery (Digital
Orthophoto Quarter Quads, DOQQ), knowledge of ecological site
descriptions (ESDs) and state-and-transition models (STMs),
existing spatial data layers, georeferenced ground data and field
traverse data. Each child polygon was attributed with an
ecological site and three-digit state code. A more detailed
description of the state mapping process is provided here:
https://jornada.nmsu.edu/esd/state-mapping.
Soil map units were obtained from the Dona Ana County Area, New
Mexico (NM690) and White Sands Missile Range, New Mexico (NM688)
SSURGO Soil Surveys:
https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx
The ecological site descriptions describing each ecological site,
and associated states, are found on the Ecosystem Dynamics
Interpretive Tool (EDIT): Ecological Site Descriptions for MLRA
042B (Southern Rio Grande Rift), Desert Shrub (R042BB***NM)
https://edit.jornada.nmsu.edu/catalogs/esd/042B.
Resources for Major Land Resource Area (MLRA) and Land Resource
Unit (LRU):
https://www.nrcs.usda.gov/resources/education-and-teaching-materials/defining-lrr-mlra-and-lru
https://web.nmsu.edu/~hbw3/what-is-a-land-resource-unit.html
STATE CODES
State codes consist of two or three digits.
Two digit codes are as follows: 10 = exotic dominated 11 = Roads
12 = Tanks/Water hole 13 = Agricultural field. Three digit codes
are composed of the following: 1 = Grassland (HCPC state) 2 =
Altered grassland / Altered savanna 3 = Shrub or Tree savanna
(HCPC state) 4 = Shrub / Tree invaded grassland 5 = Shrub / Tree
dominated 6 = Shrubland / Woodland 7 = Bare Annuals 8 = Gallery
forest (HCPC state) 9 = Exotic invaded.
State code example: 124 = reference grassland (1) is the dominant
state; secondary state is altered grassland (2) and the polygon
contains patches of shrub-invaded grassland (4)….think of a sandy
soil that is mostly black grama grassland with very sparse (<3%
cover) mesquite, but has patches with low/no black grama (<5%
cover), with or without dropseeds and three-awns; and to a lesser
extent has patches of higher density mesquite (5% cover or more)
DOMINANT SPECIES
For the dominant species variables, plant codes are from USDA NRCS
Plants Database: https://plants.sc.egov.usda.gov/java/. Functional
group codes are: AG = annual grasses; PG = perennial grasses; AF =
annual forbs; PF = perennial forbs; SH = shrubs; SS = sub-shrubs;
CAC = cactus, yucca, other succulents; TR = tree