By David Okul
Biodiversity monitoring has a vital measurement problem despite the understanding that stocktaking of biodiversity variables plays a critical part in conservation. A common approach in monitoring is using a basket of metrics as it is impossible to measure all the biodiversity variables in an ecosystem.
It goes without saying that the first step of indicator development is developing a clear and agreeable understanding of ecosystem types and subtypes for indicators. IUCN Global Ecosystem Typology is an agreed ecological classification framework that is recommended for renowned environmental accounting standards such as the System of Environmental-Economic Accounting (SEEA EA). It is a product of critical review and input from leading ecosystem scientists in the world. Furthermore, World Conservation Congress Marseille 2020, voted for a global ecosystem typology under resolution 061.
The IUCN Global Ecosystem typology is a classification system based on hierarchy. At the upper level, it defines ecosystems based on their convergent ecological functions but distinguishes ecosystems with contrasting assemblages in the lower levels.
Higher Level Classification
The top level includes five global realms. These include terrestrial, subterrestrial, freshwater, marine, and the atmosphere. Transitional realms are the intersection between the global realms as variation in nature is continuous.
The second level identifies 25 biomes. These ecosystems are created by human activities that drive and maintain their activity. The traditional definition of biomes involves the classification of continental-scale vegetation with major climate types. Modern definitions also have a basis in the terrestrial vegetation formations but also consider functional and evolutionary processes.
Level 3 has 108 ecosystem functional groups that include ecosystems within a biome with dependencies. The ecosystem functioning groups were developed by identifying key gradients in biomes and major species traits that vary among them. For example, water deficit, seasonality, temperature, nutrient deficiency, fire activity, and herbivory are the gradient filters in the terrestrial environment.
Detailed description and reference to the high-level typology https://portals.iucn.org/library/sites/library/files/documents/2020-037-En.pdf
Lower Level Classification
The first three levels focus on the functional properties of the ecosystem compared to the next three levels which focus on biogeographic and compositional features. These include biogeographical ecotypes, global ecosystem type, and sub-global ecosystem type. These lower levels of classification are often derived directly from ground observation.
- SEEA-EA recommends biogeographic ecotypes (or ecoregions) for national and subnational and not for supranational approaches such as the EU
- Like biogeographical ecotypes, both global and sub-global ecosystem types are already in use in the national structures and could be linked to the upper levels.
Concluding Remarks
The IUCN Global Ecosystem Typology presents a viable and practical framework to define the scope and context for biodiversity monitoring. It was developed by a collaboration of many reputable biogeographers around the world. As such, it remains ideal for ecosystem classification and structure. A pertinent critique of the typology is the observation of a great degree of overlap between the various classes. Moreover, some areas of their mapping are inaccurate because of human modification. Regardless, it presents an important starting point for monitoring. Furthermore, the typology recognizes 3 high levels of classification as coarse. As such, it is upon projects/researchers to refine their classification from steps four through six
David Okul is an environmental management professional with over 15 years experience on donor projects, conservation, forestry, ecotourism, and community-based natural resources management. When not working on environmental projects, he writes for Silvica on various topics. This blog’s views are personal and do not represent the organizations he is associated with.
