Biology Reference
In-Depth Information
5.1 Introduction
There is broad agreement among scientists and conservationists that alien invasive
species pose one of the foremost threats to global biodiversity today (Millennium
Ecosystem Assessment 2005). However, the scientific uncertainties regarding
biotic invasions remain high (National Academies of Sciences 2002), which hin-
ders effective management of invasive species. In particular, there is an urgent need
to improve the understanding and assessment of invasive species impacts (Ewel
et al. 1999; Parker et al. 1999; Strayer et al. 2006; Kueffer and Hirsch Hadorn,
2008). For instance, the role of biotic invasions in species extinctions is neither
well-understood nor well-documented (Gurevitch and Padilla 2004). At the same
time, potential positive functions of alien species in habitat restoration are increas-
ingly discussed (D'Antonio and Meyerson 2002; Ewel and Putz 2004; Kueffer
et al. 2007b). Removal of invasive species may lead to negative as well as positive
effects (Zavaleta et al. 2001). Philosophers argue that invasion biologists have no
well-defined concept of “harm by invasive species” and often only weak empirical
data are available to support the need for control of invasive species (Sagoff 2005).
Consequently, nature conservation managers state that an insufficient understanding
of negative impacts of various invasive species is a major obstacle to priority setting of
management actions (Kueffer et al. 2007a).
The disconnect between research and management may be related to the way
invasion biology has been historically framed. During the past decades, invasion
biology research has been strongly influenced by a conceptual framework derived
from only a few key publications (Davis 2006), notably Elton's classical topic
“The Ecology of Invasions by Animals and Plants” (1958) and the first SCOPE
Program on invasive species between 1982 and 1988 (Drake et al. 1989). The
basic assumption was that biological research on the causal processes underlying
biotic invasions would produce the necessary knowledge to tackle the environ-
mental problem of biotic invasions. However, recent research on the effectiveness
of science for environmental problem solving (Funtowicz and Ravetz 1993; Pohl
and Hirsch Hadorn 2007; Kueffer and Hirsch Hadorn, 2008) indicates that this
assumption may be flawed in two important ways. First, impacts were addressed
without explicitly clarifying human valuation. Basically, it was assumed that any
detectable effect on an ecosystem property by an alien species is problematic
(Kueffer and Hirsch Hadorn, 2008). Second, research questions were derived
from the intrascientific perspective of population and community ecology instead
of being framed from a management perspective. In contrast, an alternative
research approach would formulate research questions based on the goals,
options, and restrictions of the problem-solvers (Pohl and Hirsch Hadorn 2007).
Relevant starting questions may then be: What are the management goals in a
particular management context? What are appropriate management options?
What are the benefits and costs of different management options? A framing of
research questions that accounts for the management context from the beginning
may facilitate ecological generalizations in ways more useful for management
(Orians et al. 1986; Hirsch 1995; Kueffer 2006b).
