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framework can help build support for proposed actions or provide useful direction
for future experiments (Low et al. 2010 ; Price et al. 2012 ; Nixon et al. 2014 ).
13.2.7 Examples of STSM Applications
from Non-Bromus Systems
Here we present two examples of STSM applications to non-Bromus systems that
could similarly be applied to Bromus. Many challenges in conservation science can
be (1) traced to altered disturbance regimes, (2) caused by legacies of vegetation
classes or phases that differ from reference conditions, and (3) effectively resolved
with alternative management scenarios. Because the issues of exotic annual Bromus
control involve a wide array of ecological processes as well as economics (Chambers
2008 ; Knapp 1996 ) and land management options (Monsen et al. 2004 ), it is useful
to have a framework to integrate our current understanding, assumptions, and poten-
tial scenarios in a tractable and repeatable form. In the different applications of
STSM presented in these examples, we hope to illustrate how STSM can integrate
a wide breadth of ecological processes and management options. Specifically, these
examples were chosen to illustrate two different management-oriented uses of
STSM: (1) identification of the most cost-effective approach to control nonnative
grasses using spatial STSMs designed to consider trade-offs between monitoring
and treatment; and (2) quantification of model uncertainty when expert knowledge
is used to parameterize an STSM.
13.2.7.1 State-and-Transition Simulation Models as a Tool for Guiding
Invasive Plant Monitoring and Treatments
Despite the high economic impacts of exotic plant invasions (Pimentel et al. 2005 ),
including those of Bromus (Knapp 1996 ), control and restoration resources avail-
able for Bromus management on any one landscape are often limited and intermit-
tently available. These limited resources must be allocated to multiple activities
including treatment of detected infestations, monitoring treatment success, and
monitoring to discover previously undetected infestations. Cost-efficiency of con-
trol measures is greatly increased by discovering and treating new infestations
(“nascent foci”), before propagule banks are established at or beyond the invasion
site (Moody and Mack 1988 ; Maxwell et al. 2009 ; Frid et al. 2013a). However, (1)
land management programs are often evaluated based on numbers of acres treated,
which creates an incentive to focus all resources toward already detected infesta-
tions; (2) allocating resources toward monitoring and failing to detect any new
infestations is often viewed as a waste of resources; and (3) most land managers
lack tools to detect nascent foci or determine how much of their budget should be
allocated to monitoring versus treatment.
L. Provencher et al.