First global database of the Earth’s vegetation

To describe the global diversity of vegetation, only a few traits of each plant species need to be known. This is the conclusion of an international team of researchers led by the German Centre for Integrative Biodiversity Research (iDiv) in Halle-Jena-Leipzig, in which Swiss researchers of the ZHAW, the Swiss Federal Institute for Forest, Snow and Landscape Research WSL and the University of Zurich were also involved. In a new study published in the scientific journal “Nature Ecology & Evolution” they present the first global vegetation database including over 1.1 million complete vegetation records for all mainland ecosystems. The database is growing continuously and helps to better predict the consequences of global climate, land use change, or the impact of invasive species. In addition, for the first time, numerous questions of species diversity can be investigated globally.

Swiss contribution to database

While regional and national vegetation databases have increasingly emerged in recent years, a superordinate database has been lacking. This is why the research centre iDiv started the research initiative “sPlot” to develop and build the first global vegetation database. In extensive work, the existing data sets were standardized and merged. The ZHAW’s researcher Jürgen Dengler coordinated this work in the first three years of the project. Dirk Karger of the research institute WSL contributed the global climate model “CHELSA,” which is central to the evaluation of the database. The vegetation database "sPlot" currently contains more than 1.1 million vegetation records from all continents, which have been collected by hundreds of researchers from all over the world in the past decades. For instance, Michael Kessler from the University of Zurich contributed two vegetation databases from tropical rainforest areas that have hardly been investigated.

Temperature and precipitation not decisive

The research group combined the extensive data set of the "sPlot" vegetation database with the "TRY" database, the world's largest database for plant characteristics. "This will make it possible to investigate ecological issues for which the data basis was previously lacking," says the ZHAW researcher. For example, the research team wanted to know whether global factors influence the functional characteristics of plant communities. It turned out that temperature and precipitation have a relatively small influence, contrary to current opinion. Instead, the researchers found a close relationship between climate variables and phosphorus supply in the leaf. The longer the vegetation period, the lower the phosphorus content in the leaf - which also influences the leaf thickness. Land use by humans or interactions between plants - such as competition for nutrients, water and light - also have a much greater influence than assumed. This means that future calculations of plant production in a region cannot be carried out on the basis of simple temperature-precipitation models alone.