Background on ecosystems concepts
Ecosystems components
An ecosystem is defined as set of components, both living and non-living which interact with each via energy and material flows.
Abiotic components include factors such as
- water-amount, frequency, drainage
- air - level of purity
- exposure to sunlight -shading, aspect
- rocks and minerals - soil compisition
Biotic components
- producers - organisms which can capture an external energy source and bring it into the system
- consumers - organisms which rely on the producers for their energy
- decomposers - organisms which breakdown dead animal remains and waste materials into simpler forms which can be recycled in the system
Examples of ecosystems
Measuring the damage the spanners do
Lists of worst invasive species
Worst invasive species is a somewhat subjective term as it depends on who you are asking and where they are.
- A list of the worst 100 invasive species was published in 2000 and revised in 2004 by the ISSG in conjunction with peak biodiversity body the IUCN
- The IUCN/GISD/ISSG brought out a revised version in 2022 - Global Invasive Species Database (2022). It can be downloaded from
http://www.iucngisd.org/gisd/100_worst.php - In 2020, the European Union published the most recent list (Invasive alien species of Union concern) for EU member countries, backed by EU laws. It can be downloaded from https://ec.europa.eu/environment/nature/invasivealien/list/index_en.htm
Environmental Impact Classification for Alien Taxa (EICAT)
The definition of EICAT according to the GISD -
EICAT is the IUCN Standard for the classification of impacts of alien taxa on the environment. It is a simple, objective and transparent method that classifies alien taxa into one of five impact categories, according to the magnitude of the detrimental impacts on native biodiversity.
Each of these five impact categories represents a different impact magnitude, depending on the level of biological organisation of the native biota impacted (individual, population or community) and the reversibility of this impact. 1
Note the similarities between EICAT and the Redlist Cliassification of Endangered species.
Examples of EICAT in action
- Application of the Environmental Impact Classification for Alien Taxa (EICAT) to a global assessment of alien bird impacts
- Ranking alien species based on their risks of causing environmental impacts: a global assessment of alien ungulates