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University of Namibia (2020)

Assessment of the impact of chemical de-bushing on herbaceous vegetation and ground-dwelling invertebrate communities at Neudamm farm

Zeriua, Justine N.

Titre : Assessment of the impact of chemical de-bushing on herbaceous vegetation and ground-dwelling invertebrate communities at Neudamm farm

Auteur : Zeriua, Justine N.

Université de soutenance  : University of Namibia

Grade : Master of Science in Rangeland Resources Management (Animal Science) 2020

Résumé
This study aimed at assessing the impacts of chemical de-bushing on herbaceous plants and ground-dwelling invertebrates at Neudamm farm. Three experimental sites (camp’s 5, 6 and 7) treated in 2015, 2016 and 2017 respectively with a general purpose arboricide were selected alongside one (camp 4) untreated site. Pitfall traps were placed under 15 Senegalia mellifera trees which were strategically selected in each site. Three quadrates, two placed contiguous under the canopy and one outside the canopy of fifteen Senegalia mellifera trees were used to identify and record the herbaceous plants. The herbaceous species diversity was higher in the control camp than in the other camps (H=29.285, d.f = 3, p < 0.000), while the ground- dwelling invertebrate diversity (H= 2.497, d.f = 3, p < 0.5) and Family richness (H = 0.285, d.f = 3, p =0.963) did not differ significantly between the camps. However, species richness was higher in camp 5 (treated in 2016) than in the control camp (H= 13.085, d.f = 3, p < 0.000). The HCA on binary data separated the herbaceous plant species into 6 clusters and the pitfall traps into 7 clusters indicating the significant changes in herbaceous species and invertebrate family composition due to chemical treatment, among other factors. Grass biomass was higher in camp 5 (p < 0.001) and the control camp had the highest ground cover (H= 8.5 and p- value= 0.037). This study has shown that arboricides have significant direct negative effect on herbaceous vegetation and, to a lesser extent, on the ground- dwelling invertebrates.

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Page publiée le 13 juin 2021