I have not been able to find any definition of differential consumption online. What does it mean in this quotation?
Vertebrates can influence natural fire regimes in several ways. First, herbivores limit fuel quantity by consuming and recy- cling plant matter that would otherwise accumulate as litter, and by reducing the density of vegetation . Second, differential consumption of plant growth forms can enforce changes in the composition of vegetation and thereby alter the type and arrangement of fuel. Third, herbivory can gen- erate large-scale habitat heterogeneity, as a result of variation in herbivore activity in response to factors such as terrain and water availability [3,11], and this can mean that zones of low and high flammability are interspersed in arrangements that could impede the spread of landscape fires. Finally, herbivores and other animals may alter the abiotic environment in ways that affect flammability: by forming trails, dust-baths or leks, large animals create lines or patches of bare ground that can act as fire breaks, while some species forage by turning over or digging through the litter layer and surface soils, and in the process bury fine fuels and thus reduce fuel loads. In the sections below, we explore the evidence supporting these effects of herbivores on fuel and fire regimes, in the past and present.
Johnson, Christopher N., et al. “Can Trophic Rewilding Reduce the Impact of Fire in a More Flammable World?” Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 373, no. 1761, Dec. 2018, doi:10.1098/rstb.2017.0443