Dry forest
Dry forest is an umbrella term that can stand for all forests of dry locations or climatic zones. In the narrower sense, the tropical to subtropical seasonal dry forests and monsoon forests are usually meant. The dry forests are among other things one of the 17 global terrestrial eco-zones of the FAO ( Food and Agriculture Organization of the United Nations ).
definition
In the tropics and subtropics , rain-green dry forests grow in regions with pronounced dry seasons lasting more than about two months (i.e. months in which less than 60 millimeters of precipitation is measured per month). The trees in these forests are green in the rainy season and shed their leaves in the dry season . Their soils store enough water for the trees to survive in the dry season. In dry periods shorter than two months, in connection with at least 2000 millimeters of annual precipitation, these flow into semi-evergreen rainforests , in even drier areas into tropical savannas or shrub savannas . If they consist of thorny tree and shrub species, one speaks of thorn forests . The Asian dry forests in regions with a monsoon climate are also called monsoon forests .
Deciduous tree species predominate in tropical dry forests. The increased enjoyment of light in the dry season enables a dense undergrowth of shrub species. The biodiversity of these forests is overall less than that of tropical rainforests. Nevertheless, some regions with dry forests are among the global biodiversity hotspots .
distribution
Tropical dry forests are belt-shaped in the transition zones between tropical and subtropical latitudes in the northern and southern hemispheres, on the three continents America, Africa and Asia as well as various islands. Their distribution area includes southern Mexico, Southeast Africa, the Lesser Sunda Islands , central India, Indochina, Madagascar, New Caledonia , eastern Bolivia and central Brazil, the Caribbean, the Pacific coast of Ecuador and Peru and valleys in the northern Andes. The remaining holdings are roughly 1,048,700 square kilometers worldwide. The world's largest deposits are in the Sertão in northeastern Brazil and in the Gran Chaco in southeastern Bolivia, Paraguay and northeastern Argentina. Further closed occurrences exist on the Yucatán peninsula , in the north of Venezuela and Colombia and in a region in central Indochina. In the other regions, they usually form scattered and fragmented occurrences that are scattered in large regions. More than half of the world's population is in South America.
Threat and Conservation
Tropical dry forests are among the vegetation formations most threatened by humans worldwide. The rate of decline between 1980 and 2000 was highest in South America, while stocks in Africa and Asia remained relatively stable. The island of Madagascar was an exception with a loss of almost 18 percent. The remaining holdings are largely highly fragmented. Threat factors are the transformation into agricultural and pasture land, fire (→ in the forest fires in the lowland tropical forests of South America in 2019 , 1.4 million hectares of dry forest were burned in the Santa Cruz Department alone ), but increasingly also shifts in the precipitation zones due to man-made climate change. Only less than five percent of the world's stocks are considered to be permanently secured.
Individual evidence
- ↑ DM Olson, E. Dinerstein, E. Wikramanayake, N. Burgess, G. Powell, EC Underwood, J. d'Amico, I. Itoua, H. Strand, J. Morrison, C. Loucks, T. Allnutt, TH Ricketts, Y. Kura, W. Wettengel, K. Kassem (2001): Terrestrial Ecoregions of the World: A New Map of Life on Earth. BioScience 51: 933-938. doi : 10.1641 / 0006-3568 (2001) 051 [0933: TEOTWA] 2.0.CO; 2
- ↑ Wolfgang Frey, Rainer Lösch: Geobotany. Plant and vegetation in space and time. Springer Verlag, 2010. ISBN 978-3-8274-2335-1 . therein Chapter 9: Vegetation Areas of the Earth.
- ↑ a b David M. Olson, Eric Dinerstein, Robin Abell, Tom Allnutt, Christopher Carpenter, Loren McClenachan, Jennifer D'Amico, Patrick Hurley, Ken Kassem, Holly Strand, Meseret Taye, Michele Thieme (2000): The global 200: a representation approach to conserving the Earth's distinctive ecoregions. Conservation Science Program, World Wildlife Fund (USA), Washington. Pages 8–9.
- ^ A b Lera Miles, Adrian C. Newton, Ruth S. DeFries, Corinna Ravilious, Ian May, Simon Blyth, Valerie Kapos, James E. Gordon (2006): A global overview of the conservation status of tropical dry forests. Journal of Biogeography 33: 491-505. doi : 10.1111 / j.1365-2699.2005.01424.x
- ↑ Gunther Willinger: Different ecosystem, same reasons: In Bolivia more forest burns than in Brazil. In: Spektrum.de . November 6, 2019, accessed November 18, 2019 .