This article may be expanded with text translated from the corresponding article in German. (June 2016) Click [show] for important translation instructions. View a machine-translated version of the German article. Machine translation like DeepL or Google Translate is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia. Consider adding a topic to this template: there are already 10,006 articles in the main category, and specifying|topic= will aid in categorization. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing German Wikipedia article at [[:de:Waldsterben]]; see its history for attribution. You should also add the template ((Translated|de|Waldsterben)) to the talk page. For more guidance, see Wikipedia:Translation.
Jizera Mountains in Central Europe in 2006
Jizera Mountains in Central Europe in 2006
Tree dieback because of persistent drought in the Saxonian Vogtland in 2020
Tree dieback because of persistent drought in the Saxonian Vogtland in 2020

Forest dieback (also "Waldsterben", a German loan word) is a condition in trees or woody plants in which peripheral parts are killed, either by pathogens, parasites or conditions like acid rain, drought,[1] and more. These episodes can have disastrous consequences such as reduced resiliency of the ecosystem,[2] disappearing important symbiotic relationships[3] and thresholds.[4] Some tipping points for major climate change forecast in the next century are directly related to forest diebacks.[5]

Definition

Forest dieback refers to the phenomenon of a stand of trees losing health and dying without an obvious cause. This condition is also known as forest decline, forest damage, canopy level dieback, and stand level dieback.[6] This usually affects individual species of trees, but can also affect multiple species. Dieback is an episodic event[6] and may take on many locations and shapes. It can be along the perimeter, at specific elevations, or dispersed throughout the forest ecosystem.[7]

Forest dieback presents itself in many ways: falling off of leaves and needles, discolouration of leaves and needles, thinning of the crowns of trees, dead stands of trees of a certain age, and changes in the roots of the trees. It also has many dynamic forms. A stand of trees can exhibit mild symptoms, extreme symptoms, or even death. Forest decline can be viewed as the result of continued, widespread, and severe dieback of multiple species in a forest.[6] Current forest decline can be defined by: rapid development on individual trees, occurrence in different forest types, occurrence over a long duration (over 10 years), and occurrence throughout the natural range of affected species.[7]

History

A lot of research was done in the 1980s when a severe dieback occurred in Germany and the Northeast United States. Previous diebacks were regionally limited, however, starting at the end of the 1970s, a decline took over the forests in Central Europe and parts of North America. The forest damage in Germany, specifically, was different as the decline was severe: the damage was widespread across various tree species. The percentage of affected trees increased from 8% in 1982 to 50% in 1984 and stayed at 50% through 1987.[7] Many hypotheses have been proposed for this dieback, see below.

In the 20th century, North America was hit with five notable hardwood diebacks. They occurred following the maturation of the forest and each episode had lasted about eleven years. The most severe temperate forest dieback targeted white birch and yellow birch trees. They experienced an episode that started between 1934 and 1937 and ended between 1953 and 1954. This followed a wave pattern that first appeared in Southern regions and moved to Northern regions, where a second wave was evident between 1957 and 1965 in Northern Quebec.[8]

Dieback can also affect other species such as ash, oak, and maple. Sugar maple, particularly, experienced a wave of dieback in parts of the United States during the 1960s. A second wave occurred primarily in Canada in the 1980s, but also managed to reach the United States. These diebacks were numerically analyzed to exclude natural tree mortality. It is hypothesized that a mature forest is more susceptible to extreme environmental stresses.[8]

Potential causes of forest dieback

The components of a forest ecosystem are complex and identifying specific cause–effect relationships between dieback and the environment is a difficult process. Over the years, a lot of research has been conducted and some hypotheses have been agreed upon such as:

Some other hypotheses could explain the causes and effects of dieback. As agreed upon between the scientific exchanges of Germany and the United States in 1988:[7]

Consequences of forest dieback

Forest dieback can be caused by a multitude of factors, however, once they occur, they can have certain consequences.

Climate change

Further information: Effects of climate change and Effects of climate change on ecosystems

Changes in mean annual temperature and drought are major contributing factors to forest dieback. As more carbon is released from dead trees, especially in the Amazon and Boreal forests, more greenhouse gases are released into the atmosphere. Increased levels of greenhouse gases increase the temperature of the atmosphere. Projections for dieback vary, but the threat of global climate change only stands to increase the rate of dieback.[9]

See also

References

  1. ^ "Climate-induced forest dieback: an escalating global phenomenon?". Food and Agricultural Organization (FAO). 2009. Retrieved March 16, 2010.
  2. ^ a b c d e Sangüesa-Barreda G, Linares JC, Camarero JJ (December 2015). "Reduced growth sensitivity to climate in bark-beetle infested Aleppo pines: Connecting climatic and biotic drivers of forest dieback". Forest Ecology and Management. 357: 126–137. doi:10.1016/j.foreco.2015.08.017. hdl:10261/123320. ISSN 0378-1127.
  3. ^ a b Stursová M, Snajdr J, Cajthaml T, Bárta J, Santrůčková H, Baldrian P (September 2014). "When the forest dies: the response of forest soil fungi to a bark beetle-induced tree dieback". The ISME Journal. 8 (9): 1920–31. doi:10.1038/ismej.2014.37. PMC 4139728. PMID 24671082.
  4. ^ a b c Evans PM, Newton AC, Cantarello E, Martin P, Sanderson N, Jones DL, et al. (July 2017). "Thresholds of biodiversity and ecosystem function in a forest ecosystem undergoing dieback". Scientific Reports. 7 (1): 6775. Bibcode:2017NatSR...7.6775E. doi:10.1038/s41598-017-06082-6. PMC 5533776. PMID 28754979.
  5. ^ a b Lenton TM, Held H, Kriegler E, Hall JW, Lucht W, Rahmstorf S, Schellnhuber HJ (February 2008). "Tipping elements in the Earth's climate system". Proceedings of the National Academy of Sciences of the United States of America. 105 (6): 1786–93. doi:10.1073/pnas.0705414105. PMC 2538841. PMID 18258748.
  6. ^ a b c d Ciesla WM, Donaubauer E (1994). Decline and dieback of trees and forests: A global overview. Rome, Italy: Food and Agriculture Organization of the United Nations.
  7. ^ a b c d e f g h i j Krahl-Urban B, Papke HE, Peters K (1988). Forest Decline: Cause-Effect Research in the United States of North America and Federal Republic of Germany. Germany: Assessment Group for Biology, Ecology and Energy of the Julich Nuclear Research Center.
  8. ^ a b Auclair AN, Eglinton PD, Minnemeyer SL (1997). Principle Forest Dieback Episodes in Northern Hardwoods: Development of Numeric Indices of Aereal Extent and Severity. Netherlands: Kluwer Academic Publishers.
  9. ^ a b c Allen C, Ayres M, Berg E, Carroll A, teal (2005). "Bark Beetle Outbreaks in Western North America: Causes and Consequences" (PDF). US Forestry Service. Retrieved 17 March 2021.
  10. ^ Cunningham SC, Thomson JR, Mac Nally R, Read J, Baker PJ (2011-02-21). "Groundwater change forecasts widespread forest dieback across an extensive floodplain system". Freshwater Biology. 56 (8): 1494–1508. doi:10.1111/j.1365-2427.2011.02585.x. ISSN 0046-5070.
  11. ^ a b Adams HD, Zeppel MJ, Anderegg WR, Hartmann H, Landhäusser SM, Tissue DT, et al. (September 2017). "A multi-species synthesis of physiological mechanisms in drought-induced tree mortality". Nature Ecology & Evolution. 1 (9): 1285–1291. doi:10.1038/s41559-017-0248-x. hdl:10316/87201. PMID 29046541. S2CID 294491.
  12. ^ Prasad, M. N. Nagendra; Bhat, S. Shankara; Raj, A. P. Charith; Janardhana, G. R. (2009-02-01). "Detection of Phomopsis azadirachtae from dieback affected neem twigs, seeds, embryo by polymerase chain reaction". Archives of Phytopathology and Plant Protection. 42 (2): 124–128. doi:10.1080/03235400600982584. ISSN 0323-5408. S2CID 84610692.
  13. ^ a b Policelli N, Horton TR, Hudon AT, Patterson T, Bhatnagar JM (2020-08-06). "Back to Roots: The Role of Ectomycorrhizal Fungi in Boreal and Temperate Forest Restoration". Frontiers in Forests and Global Change. 3: 97. doi:10.3389/ffgc.2020.00097. S2CID 220975025.
  14. ^ a b Kaňa J, Kopáček J, Tahovská K, Šantrůčková H (February 2019). "Tree dieback and related changes in nitrogen dynamics modify the concentrations and proportions of cations on soil sorption complex". Ecological Indicators. 97: 319–328. doi:10.1016/j.ecolind.2018.10.032. ISSN 1470-160X.
  15. ^ "Cation Exchange Capacity and Base Saturation | UGA Cooperative Extension". extension.uga.edu. Retrieved 2021-03-29.
  16. ^ Gray E, Merzdorf J. "Earth's Freshwater Future: Extremes of Flood and Drought". Climate Change: Vital Signs of the Planet. NASA's Jet Propulsion Laboratory. Retrieved 2021-03-29.
  17. ^ Blaustein RJ (March 2011). "Amazon dieback and the 21st century". BioScience. 61 (3): 176–82. doi:10.1525/bio.2011.61.3.3. S2CID 86473306.
  18. ^ Krankina ON, Dixon RK, Kirilenko AP, Kobak KI (May 1997). "Global climate change adaptation: examples from Russian boreal forests". Climatic Change. 36 (1): 197–215. doi:10.1023/A:1005348614843. S2CID 154737245.
  19. ^ Lenton TM, Held H, Kriegler E, Hall JW, Lucht W, Rahmstorf S, Schellnhuber HJ (February 2008). "Tipping elements in the Earth's climate system". Proceedings of the National Academy of Sciences of the United States of America. 105 (6): 1786–93. doi:10.1073/pnas.0705414105. PMC 2538841. PMID 18258748.