flowchart LR E["Type E<br/>Irrigated agriculture"] -->|stop irrigation<br/>topsoil loss / wind| ABAG["ABAG state<br/>Abandoned ag · bare / eroded"] ABAG -->|planting, drip, nurse shrubs<br/>ATTO / ERNA / natives| EARLY["Early seral / planted<br/>low cover · high bare"] EARLY -->|recruitment + time<br/>no irrigation| REF["Reference-like Type A scrub<br/>ESD potential phases"] EARLY -->|fail / chronic drought<br/>or weed lock| ABAG REF -->|severe disturbance| ABAG E -.->|Plan failure path| E
State-and-transition model (STM) — draft
Gravelly loam ESD concept + abandoned-agriculture state for Laws Type E
Draft / sandbox — what this means
What: This page is an open, versioned analysis artifact—methods and numbers stay visible while tools mature (Snow et al. 2026).
Why: Closed file-share workflows hide how compliance figures were produced. Publishing drafts lets partners and the public inspect assumptions early, without treating prototypes as adopted policy or Technical Group findings.1
Companion pages
- NMDS (draft) — composition space for reference vs reveg
- Goals & caps summary — compliance milestones vs open caps
- Methods paper: STM / NMDS for Type E (draft)
Purpose
What: A draft state-and-transition model (STM) for Laws Type E parcels: plant communities an ecological site can support, the transitions among them, and which changes are hard to reverse (Bestelmeyer et al. 2017).
Why: Cover and composition goals answer compliance; they do not name the starting state after irrigated agriculture ends. Stock desert STMs usually begin from native or lightly disturbed phases. Type E transfer parcels start as abandoned irrigated agriculture—often bare, with topsoil lost to wind after irrigation stops (Green Book Type A · Barren Lands – Abag). Without an explicit ABAG box, the model pretends recovery begins from intact scrub.
ICWD’s broader Owens STM work lives in stm (Green Book types as states within NRCS ecological sites; NMDS to test type separation).
Ecological site (confirmed)
What: Majority-component SSURGO (Ecologic_3) places all five Type E parcels on Gravelly Loam 5-8” P.Z.—matching Plan “gravely loam” language used for LAW118/129 planting caps.
Why name the ESD: Caps and planting tables are ecological-site concepts; joining SSURGO makes that claim testable and mapable.
| Layer | Assignment |
|---|---|
| SSURGO / inventory name | Gravelly Loam 5-8” P.Z. |
| CA802 (Draft / empty EDIT) | R029XG009CA |
| NV Provisional twin (dynamics) | R029XY087NV |
| MLRA | 029 — Southern Nevada Basin and Range |
stm catalog status |
Tier 3 — no draft site STM page yet |
| Plan language (LAW118/129) | “gravely loam” ≤3% / species, ≤15% aggregate — ATPO basis |
| Green Book on reveg | Type A, Barren Lands – Abag (LAW118 also ~41 ac Type E on same ESD) |
| Reference parcels | Mostly Type A scrub for ATTO/ERNA caps — reference |
Rows: data/processed/laws_type_e_esd.csv. Closest published narrative twin: Loamy 5-8.2
Draft STM (Gravelly Loam 5-8” + ABAG)
| State | Meaning |
|---|---|
| E – Irrigated ag | Pre-transfer / failure-path revert |
| ABAG | Precip-only barren after irrigation ceases; topsoil depleted; high wind erosion |
| Early seral / assisted | Active revegetation; cover rising but not self-sustaining |
| Reference-like A | Composition approaching Gravelly Loam arid reference mixes |
Stock Gravelly/Loamy STMs still govern within-scrub phases (grazing, annuals, shrub dominance). ABAG is the Type E add-on.
Link to monitoring
- Cover / composition / caps are milestones on Early → Reference — revegetation, cap scenarios.
- Rest periods after goals are a completion rule, not yet an STM box — goals & caps.
- NMDS asks whether reveg composition sits apart from the reference cloud and whether years move toward it.
References
Bestelmeyer, Brandon T., Andrew Ash, Joel R. Brown, Bulgamaa Densambuu, María Fernández-Giménez, Jamin Johanson, Max Levi, et al. 2017. “State and Transition Models: Theory, Applications, and Challenges.” In Rangeland Systems, edited by David D. Briske, 303–45. Springer.
Snow, Tasha, Christopher Holdgraf, Wilson Sauthoff, Jessica Scheick, Ellianna Abrahams, Joanna Millstein, Sanjay Bhangar, et al. 2026. “A Path to Better Science Through Co-Creation and Open Infrastructure.” Perspectives of Earth and Space Scientists 7 (1): e2025CN000295. https://doi.org/10.1029/2025CN000295.