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Acidification and eutrophication of forests on sandy soil: effects of forest type and deposition load

A De Schrijver (2007)
abstract
Forests on sandy soil did clearly acidify during the past decades, what was found to be related to high depositions of potentially acidifying compounds to the forest floor. Several factors are a stimulus for high atmospheric deposition load in these types of forest ecosystems. (1) Forests are often situated in the vicinity of intensive livestock husbandry, which is the cause of high NH3 emissions to the atmosphere (one of the most important potentially acidifying pollutants at the moment). (2) Forests are often very small, so have a high surface area of forest edge (this is on average the outer 50 m zone of the forest). Forest edges act as ‘hotspots’ for potentially acidifying and nitrogen (N) deposition and can show up to four-fold increases in the rate of atmospheric delivery compared with nearby areas without edge. (3) The prevailing forest types are plantations of coniferous tree species (Pinus sylvestris, Pinus nigra) which have, in comparison to other vegetation types, a higher filtering capacity due to their higher leaf area index and evergreen character. Besides the acidification of the soil, clear symptoms of N saturation were found in several forest ecosystems. All studied vegetation types were originally N limited, so without any significant seepage of nitrate. At the moment, nitrate seepage occurs at a significantly higher rate than background levels (5 kg (357 mol) N.ha-1.yr-1), and during the entire year. When forest ecosystems are nitrogen saturated - and it might be expected that, under the current load of N emissions, this will hold true for most ecosystems on the long-term - a close relationship exists between the level of N deposition input and the level of N seepage. This work clearly demonstrates that different forest types, in this thesis simplified as coniferous versus deciduous forest types, have different impacts on ion throughfall and seepage fluxes. Coniferous forests receive significantly higher amounts of N and sulphur (S) to the forest floor than deciduous forests. Consequently, more nitrate and sulphate, and also more so-called base cations and aluminium are seeped to the groundwater. Besides a higher pollution of ground and surface water with nitrate and sulphate, the related higher seepage of so-called base cations and aluminium furthermore accounts for a higher reduction of the soil buffering capacity. From this work it can be concluded that converting coniferous Pinus nigra and Pinus sylvestris plantations into mixed species forests with Betula pendula and Quercus robur certainly diminishes the input of potentially acidifying and N deposition and consequently soil acidification and nitrate seepage to groundwater. But it should be emphasized that also in some of the observed deciduous forest types clear symptoms of a nitrogen surplus and soil acidification processes were apparent. Therefore, conversion of coniferous to deciduous forests might certainly not be seen as the solution for this environmental problem. Reducing the emission loads is a necessary condition for the sustainable protection of forest and other ecosystems on the long-term.
Please use this url to cite or link to this publication:
author
promoter
K Verheyen
organization
year
type
dissertation
DOI
1854/7642
UGent publication?
yes
classification
D1
id
468114
handle
http://hdl.handle.net/1854/LU-468114
alternative location
http://lib.ugent.be/fulltxt/RUG01/001/215/934/RUG01-001215934_2010_0001_AC.pdf
date created
2007-08-27 20:55:09
date last changed
2009-01-27 13:49:15
@phdthesis{468114,
  abstract     = {Forests on sandy soil did clearly acidify during the past decades, what was found to be related to high depositions of potentially acidifying compounds to the forest floor. Several factors are a stimulus for high atmospheric deposition load in these types of forest ecosystems. (1) Forests are often situated in the vicinity of intensive livestock husbandry, which is the cause of high NH3 emissions to the atmosphere (one of the most important potentially acidifying pollutants at the moment). (2) Forests are often very small, so have a high surface area of forest edge (this is on average the outer 50 m zone of the forest). Forest edges act as {\textquoteleft}hotspots{\textquoteright} for potentially acidifying and nitrogen (N) deposition and can show up to four-fold increases in the rate of atmospheric delivery compared with nearby areas without edge. (3) The prevailing forest types are plantations of coniferous tree species (Pinus sylvestris, Pinus nigra) which have, in comparison to other vegetation types, a higher filtering capacity due to their higher leaf area index and evergreen character. Besides the acidification of the soil, clear symptoms of N saturation were found in several forest ecosystems. All studied vegetation types were originally N limited, so without any significant seepage of nitrate. At the moment, nitrate seepage occurs at a significantly higher rate than background levels (5 kg (357 mol) N.ha-1.yr-1), and during the entire year. When forest ecosystems are nitrogen saturated - and it might be expected that, under the current load of N emissions, this will hold true for most ecosystems on the long-term - a close relationship exists between the level of N deposition input and the level of N seepage. This work clearly demonstrates that different forest types, in this thesis simplified as coniferous versus deciduous forest types, have different impacts on ion throughfall and seepage fluxes. Coniferous forests receive significantly higher amounts of N and sulphur (S) to the forest floor than deciduous forests. Consequently, more nitrate and sulphate, and also more so-called base cations and aluminium are seeped to the groundwater. Besides a higher pollution of ground and surface water with nitrate and sulphate, the related higher seepage of so-called base cations and aluminium furthermore accounts for a higher reduction of the soil buffering capacity. From this work it can be concluded that converting coniferous Pinus nigra and Pinus sylvestris plantations into mixed species forests with Betula pendula and Quercus robur certainly diminishes the input of potentially acidifying and N deposition and consequently soil acidification and nitrate seepage to groundwater. But it should be emphasized that also in some of the observed deciduous forest types clear symptoms of a nitrogen surplus and soil acidification processes were apparent. Therefore, conversion of coniferous to deciduous forests might certainly not be seen as the solution for this environmental problem. Reducing the emission loads is a necessary condition for the sustainable protection of forest and other ecosystems on the long-term.},
  author       = {De Schrijver, A},
  school       = {Ghent University},
  title        = {Acidification and eutrophication of forests on sandy soil: effects of forest type and deposition load},
  url          = {http://dx.doi.org/1854/7642},
  year         = {2007},
}

Chicago
De Schrijver, A. 2007. “Acidification and Eutrophication of Forests on Sandy Soil: Effects of Forest Type and Deposition Load.”
APA
De Schrijver, A. (2007). Acidification and eutrophication of forests on sandy soil: effects of forest type and deposition load.
Vancouver
1.
De Schrijver A. Acidification and eutrophication of forests on sandy soil: effects of forest type and deposition load. 2007.
MLA
De Schrijver, A. “Acidification and Eutrophication of Forests on Sandy Soil: Effects of Forest Type and Deposition Load.” 2007 : n. pag. Print.