Distribution mapping of world grassland types
Article first published online: 8 AUG 2014
© 2014 John Wiley & Sons Ltd
Journal of Biogeography
How to Cite
Dixon, A. P., Faber-Langendoen, D., Josse, C., Morrison, J., Loucks, C. J. (2014), Distribution mapping of world grassland types. Journal of Biogeography. doi: 10.1111/jbi.12381
- Article first published online: 8 AUG 2014
- German Federal Ministry
- Conservation biogeography;
- conservation policy;
- ecosystem management;
- highly biodiverse grasslands;
- International Vegetation Classification;
- vegetation mapping
National and international policy frameworks, such as the European Union's Renewable Energy Directive, increasingly seek to conserve and reference ‘highly biodiverse grasslands’. However, to date there is no systematic global characterization and distribution map for grassland types. To address this gap, we first propose a systematic definition of grassland. We then integrate International Vegetation Classification (IVC) grassland types with the map of Terrestrial Ecoregions of the World (TEOW).
We developed a broad definition of grassland as a distinct biotic and ecological unit, noting its similarity to savanna and distinguishing it from woodland and wetland. A grassland is defined as a non-wetland type with at least 10% vegetation cover, dominated or co-dominated by graminoid and forb growth forms, and where the trees form a single-layer canopy with either less than 10% cover and 5 m height (temperate) or less than 40% cover and 8 m height (tropical). We used the IVC division level to classify grasslands into major regional types. We developed an ecologically meaningful spatial catalogue of IVC grassland types by listing IVC grassland formations and divisions where grassland currently occupies, or historically occupied, at least 10% of an ecoregion in the TEOW framework.
We created a global biogeographical characterization of the Earth's grassland types, describing approximately 75% of IVC grassland divisions with ecoregions. We mapped 49 IVC grassland divisions. Sixteen additional IVC grassland divisions are absent from the map because of the fine-scale distribution of these grassland types.
The framework provided by our geographical mapping effort provides a systematic overview of grasslands and sets the stage for more detailed classification and mapping at finer scales. Each regional grassland type can be characterized in terms of its range of biodiversity, thereby assisting in future policy initiatives.