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management decisions; and (c) provide insight into the consequences of predicted
local climate change effects on ecological systems invaded by exotic annual Bromus
species.
Keywords State-and-transition•Conceptualmodel•Simulation•Uncertainty
- Climatechange
13.1 Introduction
Land managers dealing with impacts of exotic brome invasions are challenged with
understanding how local, site-level actions across heterogeneous landscapes and
time periods will ultimately scale up to the region where outcomes are measured
against desired conditions. State-and-Transition Simulation Modeling (STSM) pro-
vides a quantitative framework to combine these various facets at both regional and
local scales. Spatial or nonspatial analyses are used to investigate “what-if” sce-
narios that incorporate management options and evaluate sensitivity of systems to
specific parameterizations or assumptions.
This chapter is written for those who want to understand how STSMs can inte-
grate ecological and economic understanding into a simulation environment to pro-
vide insight into invasive species and vegetation management at landscape and
regional scales. The focus is on using STSMs for management of vegetation, and
particularly invasion by exotic annual Bromus (Bromus hereafter). We begin by
offering background definitions, terminology, and perspectives. We then highlight
the utility of STSMs through two published examples where STSMs have been used
in other systems to determine efficient resource allocation for monitoring exotic
grasses and to evaluate sources of uncertainty in STSMs involving expert opinion.
We conclude with a new case study application of STSMs to provide insight into the
consequences of predicted local climate change effects on ecological systems
invaded by Bromus. For further reading, several publications offer excellent descrip-
tions or reviews of STSM concepts (Czembor and Vesk 2009 ; Rumpff et al. 2011 ;
Knapp et al. 2011a, b; Daniel and Frid 2012 ).
13.2 Definition of State-and-Transition Models
Conceptual state-and-transition models are presented as discrete, box-and-arrow
representations of the continuous variation in vegetation composition and structure
of an ecological system (Westoby et al. 1989 ; NRCS 2003 ; Stringham et al. 2003 ;
Bestelmeyer et al. 2004 ). The classification of an ecological system is important for
framing each state-and-transition model. One example of a classification is the
L. Provencher et al.