1. A major challenge for the management of biological invasions is to ensure that data
and information from basic inventories and ecological research are used alongside
data from the monitoring and evaluation of interventions to trigger and improve policy
and management responses. To address this issue, South Africa has committed to
report on the status of biological invasions and their management every 3 years.
2. We propose a framework of indicators for reporting on biological invasions at a
country level; assess the feasibility of the indicators using South Africa as a case
study; and outline steps needed for indicator development.
3. We argue that a national status report on biological invasions should explicitly
consider indicators for pathways, species, and sites, and should report on interventions
in terms of inputs, outputs, and outcomes.
4. We propose 20 indicators based on data currently available, as well as existing
international policy initiatives. For each indicator, we have developed a factsheet
that includes different hierarchical metrics (considering data availability) and provide
suggestions on assigning confidence levels. We also combine these indicators
into four high-level indicators to facilitate broader reporting and describe how
forecasted indicators based on the concept of invasion debt could assist with scenario
5. We found that many of the data required for these indicators are already available
in South Africa, but they have been poorly collated to date. However, data for the
indicators of most direct value to policy and planning—those dealing with the impact
of biological invasions and the outcome of interventions—are scarce.
6. Policy implications. The framework of indicators developed here, for what we believe
is the first ever national-level report on the status of biological invasions and
their management, will facilitate the inclusion of biological invasions in environmental
reporting at national and international levels. By identifying knowledge
gaps, a status report will also focus efforts on determining the size of a country’s
invasion debt and what can be done to reduce it.