Utilizing State and Transition Models to Assist in the Decision Making Process

1. Utilizing State and Transition Models to Assist in the Decision Making Process George Peacock Grazing Lands Technology Institute USDA-NRCS

2. RANGE SITE DESCRIPTIONS • ADAPTATION OF CLIMATIC CLIMAX THEORY • GRAZING INTERPRETATIONS • PLANT COMMUNITY SCALE • SOIL MAPPING UNITS

3. RANGE SUCCESSION MODEL Above-average rainfall Drought VEGETATION Successional tendency Grazing Pressure 0 25 50 75 100 Early successional Climax Condition scale Poor Condition Excellent Condition Range Trend (adapted from Westoby, Walker, Noy-Meir 1989)

4. ECOLOGICALSITE DESCRIPTIONS • NON EQUILIBRIUM ECOLOGICAL DYNAMICS • MULTIPLE BENEFIT INTERPRETATIONS • PLANT COMMUNITY SCALE • SOIL MAPPING UNITS

5. STATE AND TRANSITION MODELS • VEGETATION STATES Different plant communities that may exist on an ecological site. • TRANSITIONS Events or actions that cause a shift from one state to another.

6. TRANSITIONS • Natural Events • climatic conditions • fire Management Actions • stocking rate • burning • brush mgt. • Natural Events X Management Actions

7. TRANSITIONS • TRIGGERS • Describe management actions required • to achieve goals and objectives. • Opportunities and Hazards • PROBABILITIES • Risk associated with actions • Integrate climate/rare events

8. THRESHOLDS • Point in time in which the boundary between 2 states is crossed • Return to original state will require management beyond simple reversal of events that caused the change. • Often associated with cultural energy management actions.

9. Semi-arid Grassland Eastern Australia Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass Recently burned, many shrub seedlings or resprouts (Westoby, Walker, Noy-Meir 1989)

10. Semi-arid Grassland Eastern Australia T1 Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass Recently burned, many shrub seedlings or resprouts Transition 1: Two or more very good rainfall years to produce many shrub seedlings. Frequency 2-5 per century. Substantial fuel of ephemerals and perennial grasses will also be produced. (Westoby, Walker, Noy-Meir 1989)

11. Semi-arid Grassland Eastern Australia T1 T2 Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass Recently burned, many shrub seedlings or resprouts Transition 2: Inevitable over time (10-20 years) as shrub seedlings grow and establish a seed bank, in the absence of fire. (Westoby, Walker, Noy-Meir 1989)

12. Semi-arid Grassland Eastern Australia T1 T2 Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass T3 Recently burned, many shrub seedlings or resprouts Transition 3: Fire, following sufficient rain to provide fuel of ephemerals. Depending upon location and completeness of shrub dominance, sufficient rain could fall 2-30 times per century. Can be blocked by grazing to remove fuel or by fire suppression. (Westoby, Walker, Noy-Meir 1989)

13. Semi-arid Grassland Eastern Australia T1 T2 Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass T4 T3 Recently burned, many shrub seedlings or resprouts Transition 4: Inevitable over time as shrub regeneration grows to maturity in absence fire. (Westoby, Walker, Noy-Meir 1989)

14. Semi-arid Grassland Eastern Australia T1 T2 Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass T5 T4 T3 Recently burned, many shrub seedlings or resprouts Transition 5: Fire, following rains adequate to produce ephemeral fuel, before transition 4 has re-established shrub regenerative capability. Probably less rain required than for transition 3, due to reduce shrub competition. (Westoby, Walker, Noy-Meir 1989)

15. Semi-arid Grassland Eastern Australia T1 T2 Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass T6 T5 T4 T3 Recently burned, many shrub seedlings or resprouts Transition 6: Fire, following exceptional rains to provide fuel of ephemerals. This transition found for fire sensitive shrubs, compare to transition 3 for resprouting shrubs. (Westoby, Walker, Noy-Meir 1989)

16. Semi-arid Grassland Eastern Australia T1 T2 Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass T7 T6 T5 T4 T3 Recently burned, many shrub seedlings or resprouts Transition 7: Fire or competition from grasses kills shrub seedlings. Blocked by grazing or fire suppression.seedlings. (Westoby, Walker, Noy-Meir 1989)

17. Semi-arid Grassland Eastern Australia T1 T2 Grassland, scattered woody plants Grassland with many shrub seedlings Dense shrub cover, little grass T7 T6 T5 T4 T3 Recently burned, many shrub seedlings or resprouts (Westoby, Walker, Noy-Meir 1989)

18. Graminoid Driven Succession Shrub Driven Succession Herbaceous Retrogression A = Tall/Mid-Grasses B = Mid/Short Grasses C = Short Grass/Annuals = Transition Threshold Perennial Grasses A B Time or Cultural Energy Increments Required to Drive System to New Configuration COMMUNITY COMPOSITION C Woody Plants Grassland Domain Shrubland Domain low Grazing Pressure high low high Fire Frequency low low Probability and Rate high Of Woody Plant Establishment Archer (1989)

19. Redland Ecological Site - Draft Edwards Plateau, Texas Oak/Grassland Ashe juniper <3 ft <5% Canopy Oak Savanna PB-PG NF-INV BM-S BM-S Seeded Site BM-S-PB-PG NF-INV BM-S BM-PB BM-S Oak/Juniper Complex 20 ft + Ashe juniper 20 + Year old stand 30% + Canopy NF-INV Oak/Juniper/ Grassland Ashe juniper 4-12 ft 10-20% Canopy 5-20 Year Old NF-INV

20. Shallow Savanna Cross Timbers, Oklahoma Oak Savanna NF-INV BM-NF BM-PB BM-PB NF-INV Mature Oak Overstory Thick Cedar BM-NF NF-INV Oak/Cedar NF-INV BM-PB BM-S BM-PB BM-S BM-S BM-S BM-PB Tall/Midgrass Seeded Site

21. DESIRED PLANT COMMUNITY • Vegetation state that has been identified to provide uses and values desired for the site. • Must provide adequate protection for the site.

22. MEETING MANAGEMENT OBJECTIVES • Similarity Index Rating indicating how nearly the present vegetation resembles desired plant community. • Planned Trend Indicates direction of plant community change in reaching management objectives. • Rangeland Health Indicator of how the ecological processes of the site are functioning.

23. Why Describe State and Transition Models? Communication tools to aid in planning and implementation. Repositories for information about the ecological dynamics of the site.

24. Why Describe State and Transition Models? Provides information that will assist land managers in making timely, well informed management decisions.