Biodiversity Mapping for Protection and Sustainable Use of Natural Resources (BIOMAPS)
The success to achieve the 2010 goals of the Convention on Biological Diversity will largely depend on credible and timely information about, for example, where centers of biodiversity are, where and by which factors biodiversity is most threatened, and where and how it can be most efficiently protected and used in a sustainable way. However, the current knowledge on regional to global patterns of biodiversity is still insufficient. Plants represent the largest group for which comprehensive distribution data are available at broad scales, and they are the structural basis of most terrestrial habitats and the foundation of food webs. Hence, understanding their spatial patterns is essential for the sustainable conservation of overall biodiversity.
Vascular plants as indicator group for the total diversity of terrestrial systems?
Biodiversity and its dramatic change play an increasingly important role in research and public discussions. Its protection and sustainable use require knowledge about its geographical distribution. One promising approach in this direction is the investigation of indicator groups, since substantial progress in the exploration of approximately 20 Mio species can hardly be expected in the near future. The well-investigated vascular plants, which comprise approximately 300,000 species, are comparatively well suited as indicator groups in terrestrial habitats. Several examples show the good correlation of their diversity with overall diversity.
Comparison of species numbers of vascular plants (following WRI 1997) to a) the sum of species numbers of tetrapods on the country level (by WRI 1997), b)estimated species numbers of insects for different regions (countries, archipelagos) world-wide (based on Table 4.5 in Gaston 1996) [after Barthlott, Kier & Mutke 1999]
Methods of biodiversity mapping
Biodiversity mapping methods can be allocated to two basic approaches (compare figure and Barthlott, Kier & Mutke 1999). In a taxon based approach, the diversity map is the result of overlaying (i.e. adding) data on the individual taxa. On the other hand, approaches based on summary data for geographical units (inventory based approaches) allow the direct processing of these summary data for different regions. Both strategies involve, to a different extent, a reduction of information.
For the inventory based approach (compare figure below), which is used in the case of the world map of the species numbers of vascular plants, data such as total species or family numbers in a region, but also taxon numbers of selected groups are recorded. These numbers may be estimated relatively reliably by specialists long before all involved taxa are exactly and systematically assessed. After standardisation of taxon numbers of regions of different sizes to a defined area size, diversity maps can be created in a rather short time and the centres of diversity can be delineated. Since the data structure is often strongly determined by political units, it is necessary to adjust the boundaries of diversity zones by superimposition with vegetation maps and data sets on physical geofactors.
This has been done by Mutke et al. (2001) using a GIS-based approach as shown in the figure to reach a complete standardisation and reproducibility of the methodology.
Quality of Biodiversity
An important question for the evaluation of biodiversity patterns is: which aspect of biodiversity is measured? Barthlott et al. (1999c) discussed a list of possible indicators. The most important are species number, different measures of rarity including endemism, phylogenetic or taxonomic diversity, intactness of ecosystems and species composition, relevance for ecosystem functioning, and current and potential economic value. Diversity patterns might change considerably with taxonomic level. Though often correlated, there might be important differences between patterns of species richness and endemism (Kier & Barthlott 2001).
Mutke and Barthlott (2000) and Mutke (2002) have shown for the United States that different measures such as species richness, family richness, endemism, percentage of rare species or of non-natives result in considerably different spatial patterns. This has important implications for conservation planning.
[Most of the analyses presented in the figure are based on the PLANTS online database of plants of the USA (USDA & NRCS 1997). Parts of the data on vascular plants in this database are copyrighted by JOHN KARTESZ of the Biota of North America Program (BONAP).
The richness at species, genus and family level is compared in figures a-c. Species numbers have been calculated for a standard area of 100,000 km2 using the equation by ARRHENIUS (1920, 1921) with z = 0.13. For the numbers of families and genera, no such standardisation technique was applied.
As a combined index of endemism and species richness, the reciprocal value of the range size within the USA was summed up for all species. This index of "range size rarity" according to USHER (1986) was interpreted as "Index of specific contribution" (Cs) or "endemism richness" by KIER & BARTHLOTT (2001). The bigger the range size of a species the smaller is its contribution to this index. As the PLANTS database only contains data on the species distributions on the state level, the sum of the area sizes of the states where the species occur is used as area of distribution in the equation of the Cs-Index.]
Kier, G., Küper, W., Mutke, J., Rafiqpoor, D. & Barthlott, W. (2006): African vascular plant species richness: a comparison of mapping approaches, pp. 409-425. In Ghazanfar, S.A. and Beentje, H.J. (Eds): Taxonomy and ecology of African plants, their conservation and sustainable use, Royal Botanic Gardens, Kew.
For research and applied purposes, reliable data are needed. However, knowledge on how these data can be used and interpreted is equally important. We present three new maps of African vascular plant species richness which are inventory-based, i.e. the underlying data are richness figures of geographic units. They are compared with three other types of diversity maps, including taxon-based maps, i.e. maps based on distribution data for individual species. The first comparison is made with respect to the flow of data and information, thereby also demonstrating some of the main differences between taxon-based and inventory-based approaches. Second, we compared the maps with respect to criteria which guide the production and use of diversity maps. These criteria are: availability of data, labour-intensity, repeatability and subjectivity of methods, accuracy of results, compatibility with geographic standards and applicability for further research, conservation and didactic purposes. The results suggest that there is no single best method. Different types of maps rather have very different strengths and weaknesses, depending on which criterion is considered. We propose to further refine mapping methods by using richness figures from floras and other inventories to calibrate taxon-based data.
Kier, G. and Barthlott, W. (2001): Measuring and mapping endemism and species richness: a new methodological approach and its application on the flora of Africa. Biodiversity and Conservation 10, 1513-1529.
The adjustment of an existing index which combines endemism and species richness (Williams 1993) is proposed so that it requires markedly less data on the study area and its flora or fauna than was necessary with the conventional calculation method. Using this adjusted method, the resulting scores are calculated and mapped for the seed plant flora of the 20 African regions as delineated by White (1983). We argue that this index, here referred to as a measure of ‘endemism richness’, can be regarded as the specific contribution of an area to global biodiversity. We demonstrate that at a given sampling scale it shows a linear relation with area. We further demonstrate that, within certain limits, this linearity can also be observed in many cases when sampling scales vary which makes the comparison of differently sized geographic units easier than is the case for species richness. The two most important advantages over species richness are that this index is more suitable to measure both the conservation value of an area and the negative impact of invaders. The latter quality is due to the fact that it yields scores which usually do not rise substantially but can rather be expected to drop in many cases when an area is invaded by alien species.
Contents
- Biomaps - Introduction
- Team
- Funding & co-operations
- Publications
- World maps of plant diversity
- BIOTA: Africa as a model continent
- Macroecological analyses of plant diversity