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the costs of a species’ continued presence and spread—including not only eco-
nomic impacts but also less easily quantifi ed impacts such as esthetics, wildfi re
risk, and loss of biodiversity—are great enough to warrant policy and manage-
ment intervention. Humans also created those impacts in the fi rst place. Humans
have facilitated, if not intentionally initiated, the spread of virtually all exotic
invasive grass species. They also directly or indirectly affect virtually all of the
disturbance processes that infl uence the abiotic and biotic processes governing
resilience and resistance to invasion (Fig. 1.1 in Germino et al. 2015b ). Therefore
to understand the dynamics of invasion and the options for management of exotic
annual grasses, it is necessary to understand the human processes that infl uence
invasion processes.
Science provides many insights regarding the biology and management of exotic
invasive species. These insights have been helpful for developing strategies not only
to treat infestations but also to reduce the likelihood of invasion in the fi rst place.
These strategies, however, require human action that is infl uenced by societal fac-
tors. Humans can choose to control weeds, but they also erect many of the greatest
barriers to control—even when they may actually hope to see the elimination of
exotic species. These barriers may occur via activities that unintentionally or
unavoidably foster continued spread of an invader or through efforts to block imple-
mentation of control options because of real or perceived side effects. It is therefore
important to understand the psychological and institutional factors that may lead to
such paradoxical outcomes.
Exotic species invasions and management are not commonly studied by social
scientists. Nonetheless, some published studies do exist, mainly by researchers
working within agricultural and natural resource academic programs. These
researchers have viewed the problem through various disciplinary lenses. Social-
psychological research explores individual-level processes such as the relation-
ships between weed knowledge, attitudes toward control, and personal behaviors
toward exotic species. Sociology, the study of groups and institutions, offers
insights into the functioning of voluntary organizations formed to address weed
issues. Policy sciences help us understand how invasive species laws and regula-
tions are formed and implemented by governmental bodies and why environmental
and industry groups respond as they do to invasive species management proposals.
In this chapter, we draw upon social science literature to improve understanding
about the connections between social and environmental processes that infl uence
invasive plant spread or control. We discuss how that understanding can inform
efforts to improve control of exotic annual grasses through education programs
and collaborative adaptive management. Our emphasis is on two exotic annual
Bromus ( Bromus hereafter) species, Bromus tectorum L. (cheatgrass or downy
brome) and Bromus rubens L. (red brome), as we found no social science informa-
tion specifi cally relevant to Bromus diandrus Roth. (ripgut brome) or Bromus
hordeaceus L. (soft brome).
M.W. Brunson and H. Kartchner