Canopy research

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Treetop path in Fischbach near Dahn

The canopy research ( english Canopy research is) still a young branch of biology , whose main objective is the ecological explore relationships on the top floors of the forests.

With the help of alpine climbing rope technique, suspension bridges, high scaffolding, mobile lifting platforms, large cranes or similar structures, but occasionally of airships is the canopy made available. Different methods are used to record animal and plant species, fungi and microorganisms, their frequency, number of individuals and vertical distribution. Particularly in the tropics, special attention is paid to the plants perched on the branches and twigs of the canopy, so-called epiphytes (for example orchids , pineapples , arum plants , but also mosses and lichens ). Physiological data of the trees (e.g. transpiration and photosynthesis rates ) are also determined. The framework for such studies is provided by accompanying meteorological investigations, such as recording temperature, humidity, radiation and wind speed in a vertical sequence from the forest floor to the crown area and beyond. As a result of these investigations, hundreds of new species that had previously escaped the eyes of researchers have been discovered in recent years, especially in tropical forests .

Research organizations

According to a report in the journal Science , several hundred physiologists , taxonomists , ecologists and environmentalists are now investigating the canopy regions of a wide variety of forests. The umbrella organizations of the canopy researchers are the Global Canopy Program (GCP) (in German: "Weltweites Baumkronenprogramm") and the International Canopy Network (ICAN) ("Internationales Baumkronennetzwerk"). The International Canopy Crane Network ("International Treetop Crane Network ") is a loose research network of cranes or similar access technologies at 11 locations, in Panama (2 cranes), French Guiana, Australia, Malaysia and Japan as well as in Germany (3 cranes), Switzerland and in a wooded area on the west coast of the USA (Northern Oregon). The “Global Canopy Program” based in Oxford ( Great Britain ) plans to set up research facilities with tree canopy access (mostly by crane) at 9 additional locations in the next few years, especially in the tropics (Africa, Brazil, India).

Research projects

This article or paragraph presents the situation in Germany . Help us to describe the situation in other countries.

One of the main interests of the canopy researchers is: a. the interactions between "above" and "below". On the uppermost floors of the forests, the trees can use the energy of the sun particularly intensively, for example to produce leaves that can serve as a food source for animals and microorganisms after the leaves have fallen on the ground: the canopy is the most productive in some forests Floor of the forest. In the tropics, however, the upper crown area can also have desert-like conditions, since in full sunlight the humidity can decrease significantly, in contrast to the shaded interior of the forest. The forest organisms have to adapt to these differences, some of which are very pronounced. This is one of the reasons why completely different species can be found in high and old forests in the crown area than on the forest floor.

Through precise and long-term observation of individual groups of trees, the growth in width of the crowns of different species in a mixed forest can also be examined. It has long been known that a forest does not have a uniformly high roof, but that different species develop their crowns at different heights, i.e. staggered. On the other hand, lateral growth is always at the expense of neighboring trees, and to this day it is completely unknown which tree species in a forest are particularly assertive.

Important projects

The crane from Leipzig-Burgaue

Researchers at the University of Leipzig have been exploring a local deciduous forest for 20 years. Since March 2001, Prof. Wilfried Morawetz has also created the possibility of doing this with the help of a crane that is located in the near-natural Leipzig floodplain forest in the north-west of Leipzig in the “Burgaue” nature reserve . The crane stands on rails and can be moved more than 100 meters. He gave an interdisciplinary research team of botanists , zoologists , meteorologists , ecologists and forest scientists the opportunity to study the entire forest up to a height of about 35 meters and to gain new insights into the flora and fauna of the treetops. The Leipzig floodplain forest had a few surprises in store: For example, scientists hadn't expected frogs in East German treetops.

Was examined u. a. also the ability of the forest to regenerate; furthermore, work was carried out on the timing of flowering phases, leaf shoots and fruit ripeness depending on the tree species and position in the crown. Studies on leaf damage and the “palatability” of leaves brought new insights into the nutritional behavior of spiders and insects, whereby the results of the studies made it clear that many species depend on natural forests with a high proportion of dead wood for long-term survival .

The scaffolding of the Kranzberger Forest

For more than a decade, scaffolding-like platforms in the forest of Kranzberg have made the crowns of a stand of beech trees 27 meters high directly accessible. As part of the Collaborative Research Center 607 of the German Research Foundation , researchers at the Technical University of Munich are investigating whether increases in plant growth - a prerequisite for competing with neighboring plants - also lead to a reduction in the ability to ward off parasites.

The researchers also infected beech branches from the crowns of sun and shade with the fungus Apiognomonia errabunda (the pathogen causing the “Apiognomonia leaf tan” in beech) and then exposed the leaves to increased ozone concentrations. It was possible to analyze how the leaf types infected with fungi react to different levels of ozone pollution.

The Hainich lifting platform

The Göttingen Geobotanikerin Annika Frech studied in the largest contiguous deciduous forest in Germany, the north-east of Eisenach located Hainich , using a so-called elevating platform such as various trees divide the canopy among themselves. Their findings from a height of up to 30 meters indicate that trees can be brought into an advantageous position not only by shading other plants, but also by using sturdy branches: when a forest tree expands its crown through strong growth, it always and quickly bumps in the crown area of ​​neighboring trees. In a storm, the branches of the competing trees often hit each other violently, which regularly results in damage; the more robust the branches, the more beneficial it is in a storm.

The Hofstetten crane

Christian Körner from Basel has been investigating the Hofstetten forest with a 45 meter high crane since 1999 . In this project, Körner fumigates part of the forest with an increased concentration of carbon dioxide (CO 2 ), as is expected in the future, in order to research the effects of this (locally) changed atmosphere on the forest and its communities (animals, plants, fungi) .

Treetop paths in Hainich

A group of the Thuringian Entomologists Association has been demonstrating the treetop path on the Thiemsburg in the Hainich National Park as a research platform for years . The first results on the biodiversity of the entomofauna in the various forest levels are already available.

See also

literature

  • Florian Zellweger et al .: Forest microclimate dynamics drive plant responses to warming. In: Science . Volume 368, No. 6492, 2020, pp. 772–775, doi: 10.1126 / science.aba6880 .
  • M. Unterseher, W. Morawetz, S. Klotz, E. Arndt (Eds.): The canopy of a temperate floodplain forest - Results from five years of research at the Leipzig canopy crane. University of Leipzig, University Press, Leipzig 2007.

Web links

Individual evidence

  1. ↑ Sky-High Experiments. In: Science . Volume 309 of August 26, 2005, p. 1314 f.
  2. ↑ www.humboldt.edu ( Memento from January 4, 2013 in the Internet Archive ) Website of Stephen Stillett, Kenneth L. Fisher Chair in Redwood Forest Ecology, Humboldt State University , until 2016. Current website (as of April 2018) Richard Preston, James Balog: Cutting edge research. In: GEO . 04/2008, pp. 92-111.
  3. ↑ atm.helsinki.fi , accessed on April 19, 2013: Overview of the research projects of the field station SMEAR II of the University of Helsinki
    RL Mauldin III, among others: A new atmospherically relevant oxidant of sulfur dioxide. In: Nature . Volume 488, No. 7410, 2012, pp. 193-196, doi: 10.1038 / nature11278
  4. ^ Canopy Access Cranes . Smithsonian Tropical Research Institute (stri.si.edu).
  5. ↑ Martin Unterseher: Tastiness of the sheets. In: Universität Leipzig (ed.): Journal. Issue 4/2007, p. 25.
  6. ^ TUM - Communications from the Technical University of Munich. Issue 3/2007, p. 47.
  7. ↑ The treetop path in Hainich. On: baumkronen-pfad.de