Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Ecological effects of Festuca costata on the Drakensberg grasslands.

Auteur : Mwambilwa, Kabemba.

Université de soutenance : University of KwaZulu-Natal

Grade : Master of Science in Grassland Sciences 2018

Résumé partiel
Fire and herbivory are important in determining the vegetation structure in savannas and grasslands. In addition, anthropogenic activities have significantly contributed to alterations in the relative abundance and distribution of plant species in many grasslands through increased nitrogen deposition and elevated concentration of carbon dioxide in the atmosphere. Using a field experiment, the study explored the effect of neighbouring plants, defoliation, and fire on the ecological performance of a major C3 grass, Festuca costata, whose range is expanding in Afro-temperate grasslands of the Drakensberg Mountains in South Africa. The experiment had three factors : fire at two levels (burned, unburned), defoliation by clipping 50mm above-ground surface, at four levels (no defoliation, defoliation of focal plant, defoliation of neighbouring plant within a 300 mm radius, and defoliation of both the focal and the nearest neighbouring grass within a 300 mm radius from the focal plant). The third factor was plant neighbourhood types at three levels (the focal plant growing alone, focal plant growing with other F. costata plants, focal plant growing with any other grass species) for a total of 24 treatment combinations with five replicates. Using a pot experiment under garden conditions, the study evaluated the influence of soil nutrient amendment with 140 KgHaˉ¹ limestone ammonium nitrate in the performance of F. costata. The variables of interest in both experiments were ; above-ground biomass production, tuft circumference, number of tillers and specific leaf area of the focal plant. Generalised Linear Models in SPSS were used to analyse the data from both experiments.

Présentation

Version intégrale (1,3 Mb)