High plant diversity is often found in the smallest areas
It may sound strange, but it’s true: the steppes of Eastern Europe are home to a similar number of plant species as the regions of the Amazon rainforest. However, this is only apparent when species are counted in small sampling areas, rather than over hectares of land. An international team of researchers led by Martin Luther University Halle-Wittenberg (MLU) and the German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig has now shown how much plant diversity estimates change when the sampling area varies from a few square meters to hectares. Their results were published in the journal Nature Communication and could be used in new, more suitable nature conservation concepts.
In their study, the team analyzed a dataset of around 170,000 vegetation plots from all climate zones on Earth. The data included information on all plant species found at a location and the coordinates of the respective area under study. The data was extracted from the world’s unique vegetation database “sPlot”, which can be found on iDiv.
“Most global biodiversity studies are conducted at a relatively large scale, such as a state or province scale. We wanted to know how much the results differ when smaller areas are examined” , explains Professor Helge Bruelheide of MLU. The team used artificial intelligence to study, among other things, the relationship between the number of plant species and the size of the area studied.
Their investigation showed that there are regions on Earth where focusing on large study areas only provides a limited understanding of the distribution of biodiversity: sometimes small areas can have relatively high biodiversity, for example in the steppes of Eastern Europe, in Siberia and in the Alpine countries of Europe. At fine spatial scales, the large difference in biodiversity between the tropics, such as the Amazon, and temperate climatic zones almost disappears.
The same applies to the African tropics, which were previously considered an exception in the tropical plant world. “The tropics have always been among the most biodiverse areas in the world. We wondered why this shouldn’t also apply to West Africa,” says Dr Francesco Maria Sabatini, who led study at MLU and is now an assistant professor at the University. from Bologna. In fact, the distribution of plant species varies widely across the African tropics, says Sabatini. These species are distributed over very large distances, so they are not always recorded when a small sample area is examined. “To correctly recognize the great biodiversity in West Africa, many small areas are needed,” adds Sabatini.
The study also shows that the spatial scale at which other highly biodiverse areas are examined, such as the Cerrado savannah region of Brazil or parts of Southeast Asia, is irrelevant. These results are also important for species protection. “Ecosystems with high biodiversity spread over a large area cannot be protected by the traditional patchwork of nature reserves. In contrast, ecosystems that have high biodiversity in a small area may well benefit from several separate protected areas,” concludes Bruelheide.
The study was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation).
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