Whole tunnel that colors zebrafish heart

Bio-News from October 26th, 2020


A study by the GFZ German Research Center for Geosciences in Potsdam examines on a global level the effects of the rock underground on biodiversity and the relief of the landscape.

Scientists have known since the 18th century at the latest that the prevailing climate is decisive for the abundance of flora and fauna in an area. However, climate differences can only explain about half of the variations in global biodiversity. The role played by the bedrock is largely unclear.


Publication:


Ott, R. F.
How lithology impacts global topography, vegetation, and animal biodiversity: A global-scale analysis of mountainous regions
Geophysical Research Letters, Vol. 47. Issue 2

DOI: 10.1029 / 2020GL088649



Richard Ott from the German Research Center for Geosciences has now used a high-resolution map of the rock subsurface to investigate globally what effects this has on vegetation density, biodiversity and the shape of the landscape. In particular, it can be proven that limestone areas are less densely overgrown and house a smaller number of amphibian, bird and mammal species. Areas in which granite or sand and clay stones predominate have the best conditions for dense vegetation and a high level of biodiversity. Another finding concerns the formation of the landscape: the influence of the climate on the average angle of inclination of a terrain, the topography as it were, appears to be less than previously assumed by some scientists.

Rock properties have a decisive influence on the development of landscapes. The mineral composition and texture of a rock largely determine the availability of water on the earth's surface, but also which nutrients get into an ecosystem and which pH values ​​the soil formed on it reaches. To investigate the influence of the bedrock, Richard Ott put global data sets in relation to one another. Among other things, he used vegetation data from satellite images, as well as biodiversity maps created by biologists. As the influence is most evident here, he focuses on mountainous and hilly areas, which make up around half of the land surface.

Richard Ott proves that areas with rocks that, among other things, weather into clays during soil formation and thus retain water better - such as granites or mudstones - usually have lush vegetation and a high level of biodiversity. Among other things, these are regions with plutonic rock and with rock deep in the earth's crust, under high pressure and temperature, mineralogically transformed, the so-called metamorphic rock.

Regions with predominantly calcareous rock, on the other hand, are usually drier, as the water flows off through cracks in the rock before plants can use it. The coastal mountains in Croatia or Greece are good examples of such regions. In these regions there are often fewer nutrients, so the plant cover is less dense and they appear bare. Another characteristic is that fewer terrestrial vertebrate species are found here. The inadequate water availability can probably also explain why amphibians are represented in such areas with fewer species.

The global overview of Ott also shows how the rock substrate influences the topography. In this study, the measure for this is how steep or sloping slopes and river beds are. Ott confirms for the global level what geologists have already shown for smaller areas: rocks that we consider hard, e.g. granite but also limestone, form slopes and river beds that are significantly steeper than those of softer rocks such as clays. These differences arise from differences in the durability of the rocks. It was previously assumed that the erosion ability of the subsoil and the steepness of the slopes are also determined by the climate. However, Ott does not find any concrete evidence for this assumption.


This news report was created with material from the Helmholtz Center Potsdam - German Research Center for Geosciences GFZ via the Science Information Service