Biology Reference
In-Depth Information
Determining the length of the resurvey period can be problematic. Too short and
undetected plants emerge after cessation of the surveys, thus largely off-setting the
eradication effort. Too long, however, also holds risks, as eradication campaigns are
expensive and potentially viewed as disruptive and intrusive by the public
(Simberloff 2003a, b). Once the plant has not been detected for several years, public
funds risk being withdrawn (Mack and Foster 2004).
As a consequence, devising effective minimal resurvey periods have consistently
been an objective of eradication campaigns (Kempton 1921; APHIS/PPQ 1992;
Panetta and Timmins 2004). The likelihood that the target species will reappear on
each surveyed site declines steeply as years elapse with no detected plants. But the
reappearance of even a single plant means that survey of the sites begins again on
a year-by-year basis. Only after no target plants have been detected at a site for
multiple years is the site released from further surveys (e.g., APHIS/PPQ 1992).
8.
Public cooperation and financial support must be sustained
. The importance of
broad public understanding for the need and feasibility of eradication is proba-
bly the most important component of a successful eradication program. Without
it, most eradication campaigns are doomed to failure, unless the invader is con-
fined to a few small sites on public lands. The value of public support is well
illustrated by comparing the outcomes of the campaigns against
S. asiatica
,
B.
vulgaris
, and
C. vulgaris
in the US.
The largest campaign of which we are aware, the attempt to eradicate
B. vulgaris
in the US, contained a decidedly mixed bag of features that could have spelled
success or failure. Although barberry is a conspicuous shrub, and the new range
was largely in a readily traversed agricultural landscape, its seeds are persistent in
the soil. Moreover, birds are effective seed dispersers, thereby opening the oppor-
tunity for reentry to cleared sites (Kempton 1921). The most serious aspect that
could have stymied eradication was barberry's huge US range (Fig. 3.1). But pub-
lic support overcame this seemingly insurmountable hurdle. Tens of thousands of
people were eventually involved in the eradication effort, not just farmers but also
seasonal eradication crews and others. Searching every parcel of land became a
competition for school children that the government heartily encouraged by
awarding medals and other recognition (Roelfs 1982)! Clear emphasis was placed
on careful survey and resurvey of this immense area for barberry, so that newly
emergent plants were eventually destroyed. Although the current witchweed cam-
paign does not encompass nearly as large an area (and the public has not been
asked to become directly involved), the program enjoys regional support in the
Carolinas even 50 years after its initiation (R. Westbrooks, pers. comm.). The
witchweed campaign would have failed utterly had not the public understood the
need to ban intercounty movement of farm implements and the repeated search
and herbicide treatment of private property - understanding reached through a
deliberate outreach effort (Sand 1990).
In contrast, widespread public support has been neither speedy nor adequate for
the eradication of
M. calvescens
in Hawaii. The public had been made repeatedly
