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Browsing (i.e., eating woody and non-woody dicotyledonous plants) and grazing (i.e., eating grass) are distinctively different types of feeding behaviour among ungulates today. Ungulates with different diets have different morphologies (both craniodental ones and in aspects of the digestive system) and physiologies, although some of these differences are merely related to body size, as grazers are usually larger than browsers. There is also a difference in the foraging behaviour in terms of the relationship between resource abundance and intake rate, which is linear in browsers but asymptotic in grazers. The spatial distribution of the food resource is also different for the different types of herbage, browse being more patchily distributed than grass, and thus browsers and grazers are likely to have a very different perception of food resources in any given ecosystem (see Gordon 2003, for review). [ABSTRACT FROM AUTHOR]

If humanity is at the brink of a ‘Golden Age', what then is the divination for nature? In this book we will try to foretell how wild herbivores will react to the changes that take place in the world in which they live. That world has been changing since it formed, and for millions of years its plants have been consumed by herbivores. This has led to adaptations in plants in reaction to herbivory, and our present-day species assemblages and landscapes are a manifestation of the forces of natural selection that have been in operation for a very long time. Over a much shorter time, these landscapes have been heavily impacted upon by humans; firstly, by accidentally burning patches of the landscape, but later as a tool to modify that landscape either for capturing or luring game or even for changing the species composition towards a modified vegetation that yields desired produce (e.g., cultivation of hazel in the Mesolithic; Simmons et al. 1981). [ABSTRACT FROM AUTHOR]

Herbivores exploit a food resource that is fundamentally different from that of most other trophic levels. Their food exists in an apparent surplus, food items are rarely eaten in entirety, and the concepts of pursuit and catchability are irrelevant (Owen- Smith and Novellie 1982; Spalinger & Hobbs 1992a). Plant foliage is generally of low nutritive value so foraging time and digestive time are important constraints. Ungulate herbivores can be broadly classified into two groups—those that feed mainly on grass, and those than feed mainly on browse. This division is important in relation to the both the way in which an animal forages, and the definition of what constitutes a patch, because grass and browse material present themselves in very different ways to the foraging herbivore, and because grasses differ from browses in architecture and physical structure (Table 5.1). [ABSTRACT FROM AUTHOR]

Ruminants are, without exception, obligate herbivores subsisting as they do on a diet composed entirely of plant material. However, plant material is a diverse resource and within the Ruminantia there is a range of feeding niches with different herbivore classes focussing their foraging effort on different vegetation types (Hofmann 1989). The plant material available to herbivores comes in a range of morphological types with the major types being grasses, forbs, and browse. Grasses (including the morphologically similar sedges) are monocotyledonous plants characterised by a basal meristem, a low growth form and a relative lack of lignified support structures (except for some of the tall tropical grasses which could be considered to be morphologically classed as browse). [ABSTRACT FROM AUTHOR]

The world on which we live is constantly changing, slowly through geological and evolutionary change and rapidly as the result of rainfall events or droughts, storms, hurricanes and cyclones, cold snaps or heat waves, and diurnal changes in light levels. Some of these changes have only local effects but others have global effects. In recent times the world has undergone a dramatic global change in form of the levels of CO2 in the atmosphere, much of it derived from anthropogenic sources (King 2005). Currently, the level of CO2, 380 ppm, has not been experienced by the biota on the planet for over 650,000 years (Siegenthaler et al. 2005). This increased CO2 level is leading to changes in climate with consequences for rainfall and temperature patterns across the globe (IPCC 2001) with knock-on effects for vegetation community composition, and plant chemistry. [ABSTRACT FROM AUTHOR]

Management of large wild herbivores sometimes includes action on the availability of resources and/or on the abundance of predators, but the management of most populations of these animals is limited to the choice of hunting quotas (Williams et al. 2002). The dynamics of the target populations, in interaction with their habitats, is therefore a central process in management. The dynamics of populations is driven by their demographic parameters, i.e., the rates of reproduction and survival. Demographic rates vary according to the sex and age of the individuals, and also show different degrees of temporal and spatial variation among populations (Gaillard et al. 2000; Coulson et al. 2001). In this chapter we first address the question: do browsing and grazing large herbivores have different demographic rates driving the dynamics of their populations? [ABSTRACT FROM AUTHOR]

Biodiversity definable as the variety of life in all its forms. Biodiversity encompasses the entire biological hierarchy. Two different hierarchical schemes are frequently used to classify biological entities (Sarkar and Margules 2002): a spatial hierarchy and a taxonomic hierarchy. The spatial hierarchy runs from biological molecules and macromolecules, through cell organelles, cells, individuals, populations and meta-populations, communities, ecosystems ultimately to the biosphere; and the taxonomic hierarchy from alleles through loci, linkage groups, genotypes, subspecies, species, genera, families, orders, classes, phyla, and kingdoms. Each level is highly heterogeneous and, even more important, most entities are poorly defined. For example, there is still much confusion about the species concept, to mention one of the key entities in biology (Sarkar and Margules 2002). Furthermore biodiversity also comprises the relationships between entities within a hierarchy. Through all the confusion of the concept of biodiversity it is very difficult to operationalise and, therefore, various proximates have been developed which allow the estimation of (subsets of) biodiversity in the field. According to Ricotta (2005): ‘biodiversity may be defined simply as a set of multivariate summary statistics for quantifying different characteristics of community structure'. [ABSTRACT FROM AUTHOR]

Large browsing and grazing herbivores can have a profound influence on the physiognomy, composition, and function of vegetation, from the landscape scale to a single plant (Hobbs 1996; Augustine and McNaughton 1998). By selective foraging among populations of plant modules and genets and along resource gradients, herbivores exert differential pressures on plant populations at different spatial and temporal scales (Kielland and Bryant 1998; Allison 1990; Price 1991; Jia et al. 1995; Danell et al. 2003). In addition, herbivore behavioural costs (predation, shelter seeking, etc.) can strongly influence locational, and therefore foraging, choice (Schmitz 2003; Letourneau and Dyer 2004). [ABSTRACT FROM AUTHOR]

Herbivores can have a wide range of effects on terrestrial ecosystems. Some of these effects are direct, such as the removal and consumption of herbage—which can vary some 100-fold across terrestrial ecosystems from less than 1% to greater than 60% (McNaughton et al. 1989)—treading on soil and vegetation, and the return of excreta (Floate 1981). Herbivores also have important indirect effects on ecosystems, altering rates of nutrient cycling and changing nutrient availability to plants (Bardgett and Wardle 2003; Bardgett 2005). These indirect effects of herbivores on ecosystems are mediated by feedbacks that occur between plants and below-ground decomposer communities, and especially soil microbes, which play a central role regulating nutrient availability to plants. [ABSTRACT FROM AUTHOR]

There are two fundamentally different ways to look on the way consumers use their resources. The first is that different species partition the resource in a particular manner, so that some species get a particular part and other species another part. In this view, the sum of the shares is equal to the total. The second way of looking at resource partitioning is shaped by thoughts about niche differentiation: species differ in their ability to extract particular resources from a continuum, and because they are different there is an additive effect if different species utilise an area together. Specialization leads to increased partitioning of resources which leads to a higher total offtake. We are interested in the question, then, whether increased species richness of vertebrates that make use of the vegetation—that is, ungulate grazers and browsers—leads to an increased offtake of the plant biomass in an area, and subsequently whether, if true, this translates into higher herbivore biomass and/or productivity. [ABSTRACT FROM AUTHOR]

Among African ruminants a clear dietary distinction exists between grazers, feeding predominantly on grasses and sedges (graminoids) year-round, and browsers consuming mostly the leaves and shoots of woody plants as well as herbaceous dicots (or forbs) and fruits (Owen-Smith 1992, 1997). Even so-called mixed feeders can be divided between a subset obtaining the greater proportion of their diet from grasses year-round (mainly grazers, e.g., Thomson's gazelle (Gazella thomsoni), and mainly browsers dependent largely on woody and herbaceous dicots, especially during the dry season (e.g., Grant's gazelle Gazella granti). Just two species seem firmly intermediate, switching between consuming mostly grass in the wet season, and a predominance of browse during the dry season: impala (Aepyceros melampus) and nyala (Tragelaphus angasi). The grazerbrowser distinction is replicated among the African rhinos, with the white rhino (Ceratotherium simum) being exclusively a grazer and the black rhino (Diceros bicornis) almost entirely a browser (Owen-Smith 1988). All extant zebras (Equus spp.) are exclusively grazers. [ABSTRACT FROM AUTHOR]

The behaviour, physiology and morphology of animals are the outcome of adaptations to particular ecological niches they occupy or once occupied. Studying the correlation between a given set of characteristics of an ecological niche and the morphological and physiological adaptations of organisms to these characteristics is one of the most basic approaches to comparative biology, and has fuelled scientific interest for generations (Gould 2002). However, current scientific standards cannot be met by mere descriptions of both the characteristics of the niche and the organism, and a (hypothetical) intuitive explanation for the adaptive relevance of the latter; the presence or absence of a characteristic must be demonstrated in sound statistical terms (Hagen 2003) ideally supported by experimental data (from in vivo, in vitro, or model assays) on its adaptive relevance. [ABSTRACT FROM AUTHOR]