Indicators for monitoring biological invasions at a national level

Abstract

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. 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. 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. 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 planning. 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. 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.

An Evaluation of the Impacts of Alien Species on Biodiversity in South Africa Using Different Assessment Methods

“…A global effort is in progress to use EICAT to assess all species in their alien ranges, and researchers from South Africa have contributed many assessments to date. Evidence-based assessments are also needed in South Africa for regular reporting on the status of biological invasions (van Wilgen and Wilson et al 2018;van Wilgen et al 2020a, Chap. 1).…”

“…For example, in some plots the number of native tree species declined by 37% (n ¼ 8) when the denstity of Prosopis doubled, while native perennial grasses and herbaceous plants were eliminated (Shackleton et al 2015). Zengeya et al (2017) and van Wilgen and Wilson et al (2018) Assignment to impact levels was based on an assessment of impact on both ecological or socioeconomic aspects, with the assignment to a level being determined by the highest impact for either ecological or socio-economic aspects. Species that were identified by the experts as having insufficient information to formulate an opinion on its impacts were classified as "Data deficient" and a species was classified as "Not evaluated" if it was not evaluated against the criteria Invasive Prosopis competes with the native Vachellia erioloba (Camel Thorn) for groundwater, increasing the likelihood of competive exclusion of Camel Thorn trees when water resources are limiting (Schachtschneider and February 2013).…”

Knowing-Doing Continuum or Knowing-Doing Gap? Information Flow Between Researchers and Managers of Biological Invasions in South Africa

“…A study by van Wilgen and Wilson (2018) argued that there are several weaknesses in South Africa's approach to the control of biological invasions. They include a lack of clear goals; no, or inadequate medium-term plans; the vagaries of uncertain funding; and an almost total absence monitoring of outcomes.…”

A four‐component classification of uncertainties in biological invasions: implications for management

“…There is also a need for metrics and indicators linking the INI continuum to field observations and management and policy decisions (Wilson et al. ). Wilson et al.…”

“…Endorsement of such frameworks by the EU could represent a leading action toward global initiatives at the UN level. There is also a need for metrics and indicators linking the INI continuum to field observations and management and policy decisions (Wilson et al 2018). Wilson et al (2014) provide an example of how to measure tree invasions in practice to ensure the effective linkage to management and policy decisions.…”