Part I: What’s the reference?

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• The rangeland health reference is based on what is possible (long-term ecological potential) for a particular soil and climate combination (i.e. ecological site)

• S&T models indicate what is realistic (based on short-term potential and limited resource availability) (i.e. communities in an ecological state)

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Knowing what’s Knowing what’s possiblepossible provides:provides:

Consistent standards for Consistent standards for inventory, assessment & inventory, assessment & monitoringmonitoring

Complete range of Complete range of management optionsmanagement options

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Knowing what’s Knowing what’s realisticrealistic provides:provides:

A secondary standard for A secondary standard for inventory, assessment & inventory, assessment & monitoringmonitoring

Complete range of Complete range of management optionsmanagement options

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Thresholds(Relatively Irreversible Transitions)

CommunityA

CommunityPathway

Reference State

Shrub/Native Perr. Grass

Alternative State

Shrub/Exotic Annual Grass – Increased Fire

Exotic Annual Grass – Increased Fire

Alternative State

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SUMMARY -- S&T modelsSUMMARY -- S&T models Ecological siteEcological site-based-based state & state &

transitiontransition conceptual modelsconceptual models can be used in two ways. can be used in two ways.

1)1) TheThe “reference state” “reference state” = what = what is is possiblepossible based on ecological based on ecological site potential site potential

2)2) Communities within aCommunities within a current current state state = what is= what is realisticrealistic

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SUMMARY -- IIRH and S&T are used:

– To determine departure from the reference state» None to Slight – expected for the

ecological site and falls within the range of variation for the indicator (no threshold crossed)

» SM, M, ME - indicates that a threshold is being approached or has already been crossed

» Extreme to Total – Up to and including maximum possible departure for the indicator

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SUMMARY -- IIRH and S&T are used: (cont)

– To identify specific issues of concern (erosion, hydrology, biotic integrity)

– To help identify and communicate management options

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Part I: What’s the reference – using IIRH together with S&T models

Part II: Reference sheet development overview

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Reference Reference sheet sheet developmendevelopment (pages 21-t (pages 21-25, 72-74)25, 72-74)

Capture spatial and Capture spatial and temporal variability temporal variability

(including (including short-termshort-term disturbance effects)!disturbance effects)! Page 74

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Reference sheet Reference sheet development (pages 21-25, development (pages 21-25, 72-74)72-74)Reference Sheet defines the “None to Slight” Reference Sheet defines the “None to Slight”

Category in the Evaluation MatrixCategory in the Evaluation Matrix

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CommunityA

CommunityPathway

Reference State

Shrub/Native Perr. Grass

Alternative State

Shrub/Exotic Annual Grass – Increased Fire

Exotic Annual Grass – Increased Fire

Alternative StateA Reference Sheet is developed for the “Reference State” of each ecological site… 16

IndicatorsIndicators. . For each indicator, describe For each indicator, describe the potential for the site. Where the potential for the site. Where possible, (1) use numbers, (2) include possible, (1) use numbers, (2) include expected range of values for above- and expected range of values for above- and below-average years for below-average years for eacheach community and natural disturbance community and natural disturbance regimes within the reference state, regimes within the reference state, when appropriate and (3) cite data. when appropriate and (3) cite data. Continue descriptions on separate Continue descriptions on separate sheet.sheet.

Composition (indicators 10 and 12) based on: __ Annual Production, __ Foliar Cover, __Biomass

Page 74Page 74

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1. Number and extent of rills: 1. Number and extent of rills: Minimal on slopes less than 10% and increasing slightly as slopes increase up to 50%. Rills spaced 15–50 feet apart when present on slopes of 10–50%. After wildfires, high levels of natural herbivory or extended drought, or combinations of these disturbances, rills may double in numbers on slopes from 10–50% after high intensity summer thunderstorms.

Composition (indicators 10 and 12) based on: __ Annual Production, __ Foliar Cover, __Biomass

Page 74Page 7418

Generating the reference Generating the reference sheetsheet

What do you need to define What do you need to define potential for an ecological site?potential for an ecological site?– Ecological Site Descriptions – Soil survey information– Ecological Reference Area(s) – Expert knowledge (old timers and

brilliant ecologists)– Other data (e.g. from LTER and other

long-term studies)

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What if I don’t have…What if I don’t have…

A state and transition model?

An ecological site description?

A soil survey?

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Generating the Reference Generating the Reference SheetSheet How do you How do you

evaluate the evaluate the quality of the quality of the information?information?– Go to the source,

or people who knew it

– Compare different sources

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No Reference No Reference Worksheet: Worksheet: don’t bother don’t bother going to the going to the field!field!

T.K. Stringham and others. 2003. State and transition modeling: An ecological process approach. Journal of Range Management 56: 106-113.

J.E. Herrick and others. 2006. An integrated framework for science-based arid land management. Journal of Arid Environments 65: 319-335.

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