Grazing and Conservation Management

Grazing and Conservation Management — the title of this book will evoke different associations depending on one’s attitude towards nature conservation. To most, grazing is linked to livestock and, therefore, the connection with nature conservation is not obvious or free from ambiguity. Thus, the first purpose of this introduction is to indicate the links between the two issues. The recent discussion in the journal Conservation Biology over the relationship between livestock grazing and nature conservation may serve as a good background. Noss (1994) questioned the role of grazing in the arid and semi-arid regions of the North American west:

This we know: cattle are not native to our rangelands and they and those who manage them have caused considerable damage by performing an uncontrolled experiment over virtually the entire extent of rangelands in western North America. With this knowledge alone it is fair to conclude that range management must be drastically reformed if our conservation mission is to be fulfilled. ... In the face of uncertainty, let the burden of proof be on those who would continue grazing to show how it benefits the native ecosystem.

In the last decades the importance of grazing as a management tool for nature conservation has increased considerably. This chapter will clarify the context in which grazing takes place. It will consider the increasing impact from large indigenous herbivores to livestock introduced by humans. For thousands of years grazing was superimposed on abiotic conditions, which have been strongly influenced by human impact. This includes the change from large-scale common grazing areas towards a landscape divided into private properties. Grazing as a conservation tool has to cope with such patterns in the landscape. We will review the changes from agricultural exploitation via maintenance management towards restoration management. The questions about the ecological frame of reference for the goal of restoration will be discussed. Finally various approaches to current grazing management will be treated.

Most of the countryside of northwestern Europe is characterized by an absence of forest. Indeed, forest covers only about 25% of France, 27% of Germany, 10% of The Netherlands and 8% of England and Wales; in western Europe only 1% is considered to be ‘old-growth’ forest (Dudley, 1992). This quintessence was captured by many seventeenth century painters, who emphasized the sky with its clouds over near-treeless landscapes. To many a citizen of today, heaths, downs, limestone grasslands and other open vegetation types are viewed as original, natural and ancient. Yet many of these vegetation types are artificial and, as such, are as unnatural as most forests of northwestern Europe.

The simplest way to discuss the effects of grazing on plant communities is to compare grazed and ungrazed situations. The results of a number of studies in which large herbivores were excluded from previously grazed landscapes/plant communities are summarized in Table 5.1. This list is certainly not complete but it allows some generalizations. Grazed areas harbour pioneer species, including annuals and biennials that have to establish from seedlings, low-stature species and rosette plants. A similar conclusion was reached by Scherfose (1993) in a literature review on the impact of grazing on plant species in salt marshes in the Wadden Sea area. The ratio of species suffering from grazing and species promoted by grazing turned out to be about 1: 1 at the lower and middle salt marsh. At the higher salt marsh more species were promoted by than suffering from grazing. After the exclusion of grazing, the aforementioned groups of species are often replaced by tall grasses and herbs accompanied by litter accumulation, and by shrubs and trees. The general pattern shows a higher above-ground standing crop M exclosures than in continuously grazed plots, as reported in a review by Milchunas and Lauenroth (1993).

In any system large herbivores can interact either directly or indirectly with other species of animals. Through the activities that herbivores bring about (Figure 6.1), direct competition may take place for resources important to other fauna. Indirect effects are the result of changes in the structure and the species composition of the vegetation, mainly through the foraging process. The effects are mediated through species-specific characteristics of the herbivore involved (e.g. grazer or browser, small size or large size), and, probably most important, through density. To evaluate properly (and judge) the interactions between large herbivores and other fauna in a given system it is important to realize where the system ranks on a scale from natural to completely influenced by humans. In general this is quite easy as most systems are to some extent managed and are ranked as semi-natural.

In western Europe marshes and estuaries have been disappearing in recent centuries due to human activities (e.g. drainage and reclamation for agricultural purposes: Finlayson and Moser, 1991; Duncan, 1992; Schultz, 1992). Wetlands are considered to be vulnerable habitats that deserve special attention for nature conservation (Finlayson and Moser, 1991). In The Netherlands some new wetlands, in total about 30 000 ha, have been created as a result of land reclamation in the past few decades. The international importance of the newly developed wetlands as breeding, wintering and stop-over sites for many bird species is closely related to the pioneer stage of these young areas. Nowadays, these areas are mostly enclosed by dikes and, although of large physical size, are no longer subject to the local water level fluctuation that is typical for natural wetlands.

In considering the concept of grazing in nature reserves, a clear distinction should be made between grazing by wild herbivores and grazing by domestic herbivores which is deployed by the ranger in order to control vegetation development. Wild herbivores, such as roe deer (Capreolus capreolus), red deer (Cervus elaphus), hare (Lepus europeus), rabbit (Oryctolagus cuniculus), herbivorous birds and insects, are not included in this chapter. Although such herbivores may have a considerable impact on the vegetation, they are, as a rule, not used as a steering mechanism to achieve management objectives. The domestic herbivores which have been introduced in nature reserves, such as cattle, horses, sheep and goats, are being used predominantly as a kind of steering mechanism (Chapter 2).

The management of large herbivores and the application of grazing in conservation management has been guided by a combination of trial-and-error and scientific investigations. This book has provided an overview of the scientific knowledge concerning relevant aspects of grazing systems and their management. In this chapter we attempt to identify scientific achievements with respect to their function in supporting the management of nature reserves. This will be done by considering fields of research that are of direct significance to management practice (Table 10.1).

This chapter evaluates the use of large grazing herbivores, mainly as a tool for conservation. What have we learnt from the past 25 years of research and how do we proceed from here? As can be noted from the previous chapters, grazing has been applied to meet various management objectives. Have these objectives been met, and if not, what are the probable causes? Was grazing the right tool in the first place?