@article{fdi:010062618,
  title = {{H}ow tree encroachment and soil properties affect soil aggregate stability in an eroded grassland in {S}outh {A}frica},
  author = {{P}odwojewski, {P}ascal and {G}rellier, {S}. and {M}thimkhulu, {S}. and {T}itshall, {L}.},
  editor = {},
  language = {{ENG}},
  abstract = {{G}ully erosion and woody plant encroachment are frequently observed in grasslands worldwide. {S}oil aggregate stability is one of the drivers of gully erosion and needs to be studied, especially in the context of both tree encroachment and gully erosion. {T}his study compared the effects of tree encroachment [paperbark thorn; {V}achellia sieberiana ({DC}.) {K}yal. & {B}oatwr. previously called {A}cacia sieberiana {DC}.] and soil surface horizon properties on the aggregate stability (as measured by mean weight diameter, {MWD}) in a degraded semihumid grassland in the {K}wa{Z}ulu-{N}atal province of {S}outh {A}frica. {S}oil properties from under trees ({UT}) and open areas ({OA}) of both an {E}ntisol within deep gullies (locally called dongas) and {A}lfisol from grasslands outside the gullies (grassland). {T}he {MWD} values were higher in the grassland (3.06 +/- 0.21 mm) than in the dongas (1.84 +/- 1.03 mm). {I}n the grassland, the {MWD} was significantly higher in the {OA} than {UT}, associated with more fine roots in the {OA}. {I}n the donga, soil properties {UT} were not significantly different than those in {OA}. {T}he soil aggregate stability showed strong local variability that depends on the age of the donga and the nature of the material that composes the pediments. {I}llite was associated with higher {MWD} values. {T}he presence of interstratified illite-vermiculite located in active donga increases the shrink-swell potential of the aggregates, exacerbating their dispersion reflected in the low {MWD} values measured, especially when {C} and root contents were also low. {T}hese results suggest that the local soil clay mineralogy controls the orientation and extension of gullies rather than soil chemistry, topography, or the size of the drainage area.},
  keywords = {{AFRIQUE} {DU} {SUD}},
  booktitle = {},
  journal = {{S}oil {S}cience {S}ociety of {A}merica {J}ournal},
  volume = {78},
  numero = {5},
  pages = {1753--1764},
  ISSN = {0361-5995},
  year = {2014},
  DOI = {10.2136/sssaj2013.12.0511},
  URL = {https://www.documentation.ird.fr/hor/fdi:010062618},
}