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The combined effect of termite bioturbation and water erosion on soil nutrient stocks along a tropical forest catena in Ghana

Kristensen, Jeppe Aagaard LU ; Boëtius, Susan Helene ; Abekoe, Mark ; Awadzi, Theodore W. and Breuning-Madsen, Henrik (2019) In Catena 178. p.307-312
Abstract


In the tropical moist semi-deciduous forests of West Africa, soil catenas with extremely gravel-rich soil horizons at the summits and upper slopes and largely gravel-free profiles at the lower slope are common. Previous investigations have suggested that these gravel layers are the result of macro-invertebrates mining of fine-grained soil material from the subsoil leaving behind the gravel, to build galleries at the surface subsequently exposing it to water erosion transport downslope. We examined the indirect effect of this process on the distribution along a soil catena of crucial base cations (Ca
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In the tropical moist semi-deciduous forests of West Africa, soil catenas with extremely gravel-rich soil horizons at the summits and upper slopes and largely gravel-free profiles at the lower slope are common. Previous investigations have suggested that these gravel layers are the result of macro-invertebrates mining of fine-grained soil material from the subsoil leaving behind the gravel, to build galleries at the surface subsequently exposing it to water erosion transport downslope. We examined the indirect effect of this process on the distribution along a soil catena of crucial base cations (Ca
2+
, Mg
2+
, K
+
) and plant available phosphorous (P), which is often growth-limiting in these tropical ecosystems. We found that the export of fine-grained soil material at the top of the catena reduces the soil stocks (to 1 m) of these elements by up to 60%, while the soil fertility downslope did not change significantly. This important long-term (100–1000 yr scale) reduction in soil fertility at the top of slopes resulting from bioturbation and water erosion is overlooked in contemporary literature, which primarily focus on the beneficial impact termites and ants have on ecosystem functioning in more level savannah landscapes. As the type of catena studied is widespread across tropical environments, this effect is likely ecologically substantial. Future research should aim at understanding such long-term consequences of bioturbation on landscape ecology as well as soil heterogeneity and fertility, so we do not overlook potential negative ecosystem effects.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Ecosystem functioning, Nutrient stock depletion, Soil erosion, Termite bioturbation, Tropical forest catena, West Africa
in
Catena
volume
178
pages
6 pages
publisher
Elsevier
external identifiers
  • scopus:85063348434
ISSN
0341-8162
DOI
10.1016/j.catena.2019.03.032
language
English
LU publication?
yes
id
ffb5373b-ae29-46ca-8379-1ea47117c889
date added to LUP
2019-04-01 14:06:18
date last changed
2020-10-07 06:23:18
@article{ffb5373b-ae29-46ca-8379-1ea47117c889,
  abstract     = {<p><br>
                                                         In the tropical moist semi-deciduous forests of West Africa, soil catenas with extremely gravel-rich soil horizons at the summits and upper slopes and largely gravel-free profiles at the lower slope are common. Previous investigations have suggested that these gravel layers are the result of macro-invertebrates mining of fine-grained soil material from the subsoil leaving behind the gravel, to build galleries at the surface subsequently exposing it to water erosion transport downslope. We examined the indirect effect of this process on the distribution along a soil catena of crucial base cations (Ca                             <br>
                            <sup>2+</sup><br>
                                                         , Mg                             <br>
                            <sup>2+</sup><br>
                                                         , K                             <br>
                            <sup>+</sup><br>
                                                         ) and plant available phosphorous (P), which is often growth-limiting in these tropical ecosystems. We found that the export of fine-grained soil material at the top of the catena reduces the soil stocks (to 1 m) of these elements by up to 60%, while the soil fertility downslope did not change significantly. This important long-term (100–1000 yr scale) reduction in soil fertility at the top of slopes resulting from bioturbation and water erosion is overlooked in contemporary literature, which primarily focus on the beneficial impact termites and ants have on ecosystem functioning in more level savannah landscapes. As the type of catena studied is widespread across tropical environments, this effect is likely ecologically substantial. Future research should aim at understanding such long-term consequences of bioturbation on landscape ecology as well as soil heterogeneity and fertility, so we do not overlook potential negative ecosystem effects.                         <br>
                        </p>},
  author       = {Kristensen, Jeppe Aagaard and Boëtius, Susan Helene and Abekoe, Mark and Awadzi, Theodore W. and Breuning-Madsen, Henrik},
  issn         = {0341-8162},
  language     = {eng},
  pages        = {307--312},
  publisher    = {Elsevier},
  series       = {Catena},
  title        = {The combined effect of termite bioturbation and water erosion on soil nutrient stocks along a tropical forest catena in Ghana},
  url          = {http://dx.doi.org/10.1016/j.catena.2019.03.032},
  doi          = {10.1016/j.catena.2019.03.032},
  volume       = {178},
  year         = {2019},
}