Bush encroachment
The encroachment is the spread of shrubs and trees in pastures , grassland , heathland and savannah . In the Alpine region one also speaks of ganding . They are often the preliminary stage to reforestation : young trees can develop well in prickly bushes, protected from browsing . Scrub and forest cover are a form of succession .
Natural bushes
In areas that were originally forested (e.g. Central Europe), the meadow as part of the cultural landscape requires human maintenance. If the management ends in social fallow land or at border locations and the use ceases, a fallow land is created . The shrubbery creates bush formations first, then forest. The large herbivores that were once native to Central Europe, such as bison, aurochs, red deer and wild horses, were able to counteract this process.
Meadows and heathland are often worthy of protection due to their biodiversity and to preserve the traditional cultural landscape . The encroachment is therefore counteracted by de-puddling or grazing . In grazing projects , sheep , goats , rear cattle and horses are used seasonally or all year round to keep larger areas open.
The structural change in Alpine agriculture often means that alpine pastures are no longer maintained and given up. The consequence of this is a clearly observable encroachment ( aging ). The work step that is supposed to protect the Alps from encroachment is swiveling .
Other cultural landscapes also fell into bushes when they were no longer maintained as a cultural landscape. Many steep slopes in the eastern German wine-growing regions of Saale-Unstrut and Saxony were left to their own devices after the phylloxera disaster at the end of the 19th century (see also phylloxera disaster in the Loessnitz ). In many places, forest areas had developed through scrub and forest cover, which were only broken up again after the fall of the Wall.
Savannah bushes
Bush encroachment in savannah areas is a global process that represents a transition from previously grass-dominated ecosystems with isolated bushes to bush-dominated systems with greatly reduced grass cover and larger areas of open ground.
causes
The factors that lead to this change in vegetation are complex and have been widely discussed in specialist circles over the past few decades. Factors that lead or contribute to bush encroachment include anthropogenic disturbances such as overgrazing , avoidance of natural bushfires and exclusion of leaf-eaters, as well as climatic factors such as the global increase in atmospheric carbon dioxide , which inhibits the growth of bushes with a C3 metabolism compared to grasses, favored with a C4 metabolism . Many of these factors mutually reinforce each other or, in addition, lead to far-reaching feedback processes, which can lead to further land degradation within the ecosystem , for example through increased wind and water erosion.
Effects
Bush encroachment can have negative consequences for the affected ecosystem. This includes reduced groundwater input , reduced agricultural productivity (especially in pasture farming due to the reduced amount of grass) and a reduction in biodiversity . Scientific studies show that u. a. Rodents, reptiles, predators and arthropods can be negatively affected by the high bush cover, but this effect is very context-dependent.
Web links
- Overgrazing is not the only cause of bush cover related to savannah bush cover
Individual evidence
- ↑ Almweide · Area development. Retrieved April 15, 2015 .
- ↑ David J. Eldridge, Matthew A. Bowker, Fernando T. Maestre, Erin Roger, James F. Reynolds: Impacts of shrub encroachment on ecosystem structure and functioning: towards a global synthesis . In: Ecology Letters . tape 14 , no. 7 , 2011, ISSN 1461-0248 , p. 709–722 , doi : 10.1111 / j.1461-0248.2011.01630.x , PMID 21592276 , PMC 3563963 (free full text).
- ↑ Niels Dreber, Niels Blaum: Shrubbery African savannas: A threat to biodiversity? In: Lozán, JL, S.-W. Breckle, R. Müller & E. Rachor (eds.): Warning signal climate: The biodiversity . 2016, ISBN 978-3-9809668-1-8 , pp. 210–215 (www.klima-warnsignale.uni-hamburg.de. Doi: 10.2312 / warnsignal.klima.die-Biodiversität.34).