Ecological Site Descriptions: A Tool for the Decision Maker

1. Ecological Site Descriptions: A Tool for the Decision Maker Jon Gustafson State Rangeland Management Specialist Davis, CA

2. Lecture Format • Define Ecological Site • Compare range site descriptions and ESDs • Define some terms • Explain the state and transition model concept

3. ECOLOGICAL SITE DEFINITION: A distinctive kind of land with specific physical characteristics that differs from other kinds of land in its ability to produce a distinctive kind and amount of vegetation.

4. Analyze Resource Data Inventory Resources Identify Problems Determine Objectives Formulate Alternatives Evaluate Alternatives Make Decisions Evaluate the Plan Implement The Plan

5. Loaf of Bread, Quart of Milk N Drive down Main Street two blocks. Make a left at the stop sign and continue six blocks. Take a right onto South Street and you will see the store on the left hand side of the road after a while.

6. Assumptions We Make • Not all plant communities will occur on all types of soil • Similar soils in similar climates will produce similar plant communities in similar quantities and these communities will respond similarly to disturbance • The ecological function of soils and plant communities can be altered such that the system will not recover on its own

7. ESD Delineation at the Soil Mapping Unit Level Describes Vegetation Components Describes Range Production for that Site Process Based Accounts for Management (SRM def) Range Site Description Delineation at the Soil Mapping Unit Level Describes Vegetation Components Describes Range Production for that Site Focus of Description is Forage Production Often Prescribes Management ESD vs. Range Site Descriptions

10. On any given ecological site… • Management can drive a plant community in one direction or another as a result of changes in soil chemistry, hydrology, soil structure, competition and other ecological factors • Patterns of cause and effect can be used to describe ecological dynamics in a useful manner

11. Clementsian Approach Climax Community Seral Stage 2 Seral Stage 1 Primary Succession

13. The Core of the ESD Concept: State and Transition Models • A diagram of site plant assemblage dynamics (state and transition model) • Discrete plant community states • Pathways that cause one plant assemblage or state to become another assemblage or state • Thresholds which indicate the difference between states

14. State A recognizable, resistant and resilient complex of two ecosystem components, the soil base and the vegetation structure

15. Transition A transition indicates that a change has occurred to move from one state to another. Several plant communities may occur within the same state –if they are relatively discrete and identifiable.

16. Threshold A threshold defines the difference between states. Within a state, stable plant assemblages (communities) can be shifted from one to another with relative ease. Transitions between one state and another are considered to be irreversible in the absence of very significant energy inputs.

17. In Other Words You have crossed a threshold. You can’t go back. …unless you are made from equal parts gold and water.

18. Deep Redland Ecological Site - Draft MLRA 81C

19. Gravelly Clay Loam Bottomlands Draft Flooding Yellow Willow-Blackberry/ Sedge-Rush Complex Sycamore-Elderberry/ Sedge-Rush Complex Bank Loss S1 T1: Hydrologic Alteration: Channel Elevation Drop $$$ $$$ Arroyo Willow- Bluegrass T2: Hydrologic Alteration: Channel Elevation Drop $$$ Exotic Annual Grasses S2 S3

20. How ESDs Help • Understanding ecological processes within plant communities on specific soils (ecological sites) can highlight opportunities for improvement • Being able to recognize indicators of healthy ecological conditions provides landowners with positive feedback about their management (rangeland health evaluation) • Understanding how ecological sites become susceptible to degradation can help avoid problems (monitoring)

21. Finally… • ESDs can provide valuable information regarding what ecological functions are critical in maintaining discrete ecological states • Since reversing the decline of site having crossed a threshold is very expensive, it is always cheaper to work within the constraints of an impaired state to stabilize ecological functions • Restoration of ecological functions should be addressed if long term plant restoration is to be realized

22. Where do we find this information? • ESIS http://esis.sc.egov.usda.gov/ • Section II of the Field Office Technical Guide (FOTG) • EFOTG