Woody Invasive Species: A Regional Assessment - IUCN Invasive ...

Vielle IAS Management Priorities for Seychelles
Carlstrom further states that Island communities are more likely to lose species from
invasive exotic plant species than are analogous mainland areas. The exotic species may
displace indigenous species through competition, or reduce biodiversity through the
altering of the physical environment, increased erosion and perhaps the disruptive effects
on nutrient recycling. The survival of many of the indigenous species probably hinges on
the active control of the most aggressive alien species and this is where the management
priority for invasive plant species in Seychelles lies.
In this article I will not summarise the results of the FAO survey for the Seychelles
(Kueffer and Vos this volume) but will interpret it by giving representative examples.
Three types of insights can be expected from the regional survey:
1. New ideas
2. Learning from experiences made by others, and
3. A bird-eye view of the involved issues that allows to set priorities
Learning from the experiences of others will help to avoid mistakes. The setting of
priorities assures that energy and resources are invested where it is most efficient.
However, a regional survey cannot provide ready-made solutions for application.
Therefore the subtitle of my presentations reads as ‘a basis for discussions’. I present
examples but not final answers. At the end of my presentation as well as of today’s
presentation we will have time here in the audience to start discussions and to start work
towards future solutions of the invasive species problem in the Seychelles.
My presentation is divided into two parts. First, I take a plant-species perspective and
discuss the management of single species in parallel to the management steps scheme
introduced by Christoph & Pierre in their presentation (Kueffer and Vos this volume)
namely:
1. Priority Species for Control Measures
2. Priority Species for Close Monitoring
3. Priority Species for Border Control
I present examples not complete lists of species to illustrate the concepts.
Secondly I will discuss possible milestones for the control of invasive species in the
short, mid and long-terms.
Priority species for control measures
This refers to species that should be controlled by mechanical or chemical control in the
field, are chosen according to the following three criteria:
1. negative impact on biodiversity
2. feasibility of control (that is abundance and stage of invasion) and
3. visibility
I present several examples.
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