Estimates of vegetation greenness have been commonly used to gain information on herbivores' resource use (i.e. cattle). Green vegetation is considered of higher quality than senescent vegetation (Van Soest, 1996) because as leaves senesce, the proportion of cell wall fibre relative to cell contents increases and the cell wall lignifies (Owen-Smith, 2002). Ecologists have started to use remote sensing data on vegetation greenness to assess herbivores' resource use at larger spatial scales (Pettorelli et al., 2006; Wiegand et al., 2008) than traditional, locally collected field data would have allowed (Macandza, 2009; Parrini & Owen-Smith, 2010). The strength and nature of the relationship between vegetation greenness and herbivores' resource use are however dependent upon the scale at which data are interpreted (Marshal et al., 2011) as herbivores' resource use is a process that takes place at different hierarchical levels (Senft et al., 1987; Leblond, Dussault & Quellet, 2010). To address the hierarchical nature of the resource selection process by herbivores, data collected across different scales need to be comparable or else there is a potential disconnect in our understanding of the resource selection process. How do we make field estimates comparable with remote sensing estimates?
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.