Biology and anthropology of plant invasions - Invasive Plants: Ecological and Agricultural Aspects - page 207

Biology and anthropology of plant invasions
Jack Dekker
Weed Biology Laboratory, Department of Agronomy, Iowa State University, Ames, Iowa 50011, USA
Introduction
Invasive plants have a significant effect on the biological and human commu-
nities in which they appear. These effects include economic, environmental,
aesthetic, and biological harm to biodiversity, ecosystem function, and human
welfare. The appearance of invasive plants in terrestrial and aquatic landscapes
is associated with perturbations resulting from human population growth and
activity that affect the environment. There exists a perception that invasive spe-
cies are increasing of late due to increased global movement of people, trade,
and transport of biological and agricultural commodities and novel plant mate-
rials. Pimentel et al. [1] estimate that non-indigenous species in the US cause
environmental damage of more than $138 billion per year. They estimate there
are 50,000 foreign species in the US, and that 42% of the native species on the
US Federal Threatened or Endangered Species lists are at risk because of these
foreign invaders. Conversely, non-native species contribute to the useful crop
and animal species used for human food consumption, as well as other species
used for land restoration, biological pest control, sport, pets and food process-
ing. Other introduced species have caused economic, environmental and aes-
thetic harm in human managed and native biological communities.
To mitigate or ameliorate the harm caused by invasive species, knowledge
of their biology and behavior is needed. This management information is often
incomplete, especially that concerning behavior in the newly invaded commu-
nities and the life history traits they possess allowing invasion. Also of critical
importance is consideration of the roles played by human activity, perception,
public policy and social values. Management of plant invasions is a complex
task, requiring consideration of the roles played by the biological community
and humans, both of which must be considered in any rational management
system.
With these challenges to invasive plant management in mind, herein is
posed a conjecture that a successful plant invasion is the consequence of the
presence of a non-native species possessing life history traits suitable to
exploit an opportunity space in a particular locality. An invasive species must
successfully survive three processes: dispersal into new locality, followed by
colonization and enduring occupation of the habitat. The last part of the con-