# Presentation: 503711

## Utilizing State and Transition Models

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

- George Peacock
- Grazing Lands Technology Institute
- USDA-NRCS

## RANGE SITE DESCRIPTIONS

***RANGE SITE DESCRIPTIONS***

**ADAPTATION OF CLIMATIC CLIMAX THEORY**
**GRAZING INTERPRETATIONS**
**PLANT COMMUNITY SCALE**
**SOIL MAPPING UNITS**

## RANGE SUCCESSION MODEL

**VEGETATION**

**Above-average rainfall**

**Successional tendency**

**Drought**

**Grazing Pressure**

**RANGE SUCCESSION MODEL**

**Excellent Condition**

**Climax**

**Poor Condition**

**Early successional**

**Condition scale**

- (adapted from Westoby, Walker, Noy-Meir  1989)

**0 **

**25**

**50**

**75**

**100**

**  ****Range Trend**

## ECOLOGICALSITE DESCRIPTIONS

***ECOLOGICAL******SITE DESCRIPTIONS***

**NON EQUILIBRIUM ECOLOGICAL DYNAMICS**
**MULTIPLE BENEFIT INTERPRETATIONS**
**PLANT COMMUNITY SCALE**
**SOIL MAPPING UNITS**

## STATE AND TRANSITION MODELS

***STATE AND TRANSITION MODELS***

**VEGETATION STATES**

**	****Events or actions that cause a shift**
**          ****from one state to another.**

**	****Different plant communities that**
**          ****may exist on an ecological site.**

**TRANSITIONS**

## TRANSITIONS

***TRANSITIONS***

**Natural Events**

**Natural Events X Management Actions**

**climatic conditions**
**fire**

** ****Management Actions**

**stocking rate**
**burning**
**brush mgt.**

## TRANSITIONS

***TRANSITIONS***

**TRIGGERS**

**PROBABILITIES**

**Describe management actions required**
**	****to achieve goals and objectives.**
** ****Opportunities and Hazards**

**Risk associated with actions**
**Integrate climate/rare events**

## THRESHOLDS

***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.**** **

## Semi-arid Grassland

- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

- (Westoby, Walker, Noy-Meir  1989)

## Semi-arid Grassland

- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

- (Westoby, Walker, Noy-Meir  1989)

**T1**

**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.**

## Semi-arid Grassland

- Grassland
- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

**T1**

**T2**

**Transition 2: Inevitable over time (10-20 years) as shrub seedlings grow and**
**establish a seed bank, in the absence of fire.**

## Semi-arid Grassland

- Grassland
- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

**T1**

**T2**

**T3**

**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.**

## Semi-arid Grassland

- Grassland
- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

**T1**

**T2**

**T3**

**T4**

**Transition 4: Inevitable over time as shrub regeneration grows to**
**maturity in absence fire.**

## Semi-arid Grassland

- Grassland
- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

**T1**

**T2**

**T3**

**T4**

**T5**

**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.**

## Semi-arid Grassland

- Grassland
- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

**T1**

**T2**

**T3**

**T4**

**T5**

**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.**

**T6**

## Semi-arid Grassland

- Grassland
- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

**T1**

**T7**

**T2**

**T6**

**T3**

**T4**

**T5**

**Transition 7: Fire or competition from grasses kills shrub seedlings.**
**Blocked by grazing or fire suppression.seedlings.**

## Semi-arid Grassland

- Grassland
- with many shrub
- seedlings

-    Grassland,
- scattered woody
-        plants

-     Dense
- shrub cover,
-   little grass

**Semi-arid Grassland**
**  ****Eastern Australia**

- Recently burned,
-     many shrub
-    seedlings or
-      resprouts

**T1**

**T7**

**T2**

**T6**

**T3**

**T4**

**T5**

## COMMUNITY COMPOSITION

**Shrub**

**Driven Succession**

**Driven Succession**

**Graminoid**

**Herbaceous**

**Retrogression**

**A**

**B**

**C**

**A = Tall/Mid-Grasses**
**B = Mid/Short Grasses**
**C = Short Grass/Annuals**
**    ****= Transition Threshold**

**Shrubland Domain**

**Grassland**
** ****Domain**

**Grazing Pressure**

**Fire Frequency**

**Probability and Rate**

**Of Woody Plant Establishment**

** ****low**

**high**

** ****low**

** ****low**

** ****low**

** ****high**

**high**

**Perennial Grasses**

**Woody Plants**

**COMMUNITY COMPOSITION**

**Time or Cultural Energy Increments**
**Required to Drive System**
**to New Configuration**

**Archer (1989)**

## Redland Ecological Site - Draft

- Seeded Site

**Redland Ecological Site - Draft**
**  ****Edwards Plateau, Texas**

- Oak/Juniper Complex
- 20 ft + Ashe juniper
- 20 + Year old stand
- 30% + Canopy

- Oak/Grassland
- Ashe juniper <3 ft
- <5% Canopy

- Oak/Juniper/
- Grassland
- Ashe juniper 4-12 ft
- 10-20% Canopy
- 5-20 Year Old

**PB-PG**

**NF-INV**

**NF-INV**

**NF-INV**

**NF-INV**

**BM-S**

**BM-S**

**BM-S**

**BM-S-PB-PG**

**BM-PB**

**BM-S**

## Shallow Savanna

- Seeded Site

**Shallow Savanna**
**  ****Cross Timbers, Oklahoma**

**BM-PB**

**BM-NF**

**BM-PB**

**BM-PB**

- Oak/Cedar

- Thick Cedar

- Tall/Midgrass

- Mature Oak Overstory

**NF-INV**

**NF-INV**

**NF-INV**

**BM-S**

**BM-S**

**BM-S**

**BM-S**

**BM-PB**

**NF-INV**

**BM-PB**

**BM-NF**

## DESIRED PLANT COMMUNITY

***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.**

## MEETING MANAGEMENT OBJECTIVES

***MEETING MANAGEMENT OBJECTIVES***

**Similarity Index**

**Rangeland Health**

**Planned Trend**

**  ****Rating indicating how nearly the present**
**  ****vegetation resembles desired plant community.**

**  ****Indicates direction of plant community change**
**  ****in reaching management objectives.**

**  ****Indicator of how the ecological processes**
**  ****of the site are functioning.**

## Why Describe State and Transition Models?

***Why Describe State and Transition Models?***

**Communication tools to aid in planning and implementation.**
**Repositories for information about the ecological dynamics of the site.**

## Why Describe State and Transition Models?

***Why Describe State and Transition Models?***

**Provides information that will assist land managers in making timely, well informed management decisions.**

## Slide 25