Positive versus negative environmental impacts of tree encroachment in South Africa

Autor: Séraphine Grellier, Simon Lorentz, Luc Abbadie, Pascal Podwojewski, David Ward, Sébastien Barot, Jean-Louis Janeau, Christian Valentin
Přispěvatelé: WEO Department, University of sciences and technologies of hanoi (USTH), University of KwaZulu-Natal (UKZN), Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), University of Science and Technology of Hanoi (USTH), University of KwaZulu-Natal [Durban, Afrique du Sud] (UKZN), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2013
Předmět:
0106 biological sciences
INVASION
Acacia
DIVERSITE SPECIFIQUE
SAVANE
QUALITE
010603 evolutionary biology
01 natural sciences
Grassland
AZOTE
COMPETITION INTERSPECIFIQUE
PROPRIETE PHYSICOCHIMIQUE
DYNAMIQUE DE VEGETATION
Magnesium ion
Ecology
Evolution
Behavior and Systematics
Nature and Landscape Conservation
2. Zero hunger
Biomass (ecology)
geography
geography.geographical_feature_category
BIOMASSE
biology
SOL
Ecology
Agroforestry
STRATE HERBACEE
PATURAGE
Acacia sieberiana
ARBUSTE
PLANTE FOURRAGERE
04 agricultural and veterinary sciences
Soil carbon
15. Life on land
Herbaceous plant
biology.organism_classification
CARBONE
Agronomy
13. Climate action
[SDE]Environmental Sciences
040103 agronomy & agriculture
0401 agriculture
forestry
and fisheries
HERBACEE
ZONE DE MONTAGNE
Woody plant
IMPACT SUR L'ENVIRONNEMENT
Zdroj: Acta Oecologica
Acta Oecologica, Elsevier, 2013, 53, pp.1-10. ⟨10.1016/j.actao.2013.08.002⟩
Acta Oecologica, 2013, 53, pp.1-10. ⟨10.1016/j.actao.2013.08.002⟩
ISSN: 1146-609X
DOI: 10.1016/j.actao.2013.08.002⟩
Popis: International audience; Woody plant encroachment in grasslands is a worldwide phenomenon. Despite many studies, the consequences of woody plant encroachment on sub-canopy vegetation and soil properties are still unclear. To better understand the impacts of trees on grassland properties we examined the following questions using a mountainous sub-tropical grassland of South Africa encroached by an indigenous tree, Acacia sieberiana as a case study: (1) Do trees increase sub-canopy herbaceous diversity, quality and biomass and soil nitrogen content? (2) Do large trees have a stronger effect than medium-sized trees on grass and soil properties? (3) Does the impact of trees change with the presence of livestock and position of trees in a catena? We studied grass and non-graminoid species diversity and biomass, grass quality and soil properties during the wet season of 2009. Nitrogen in grass leaves, soil cation exchange capacity and calcium and magnesium ion concentrations in the soil increased under tall Acacia versus open areas. Medium-sized Acacia decreased the gross energy content, digestibility and neutral detergent fibre of grasses but increased the species richness of non-graminoids. Tall and medium Acacia trees were associated with the presence of Senecio inaequidens, an indigenous species that is toxic to horses and cattle. The presence of livestock resulted in a decrease in herbaceous root biomass and an increase in soil carbon and leaf biomass of grass under Acacia. Tree position in the catena did not modify the impact of trees on the herbaceous layer and soil properties. For management of livestock we recommend retaining tall Acacia trees and partially removing medium-sized Acacia trees because the latter had negative effects on grass quality.
Databáze: OpenAIRE
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