Introduction

Ecosystem services for the benefit of people are to a large extent determined by the functioning of the ecosystems involved. When taking the classification of the MEA (2005), it is apparent that provisioning services, such as food and water supply, are directly related to quantities (of energy, water, and other substances) and quality (e.g. food quality or drinking water quality) delivered by ecosystems. Also supporting services, such as nutrient cycling, directly relate to quantity and quality of particular ecosystem processes (de Bello et al., 2010). To a lesser extent, this is also true for regulating services such as flood or fire control and cultural services. These latter two categories might be more directly related to the stability and biodiversity of ecosystems (as described in Chapter 2 of this book); see Figure 3.1.

So, in order to predict and quantify provisioning and supporting services, we need to understand the quantity and quality of products delivered by ecosystems. In other words, we need to understand how ecosystems function. While most of the literature on the valuation of ecosystem services so far has mainly focused on the quantities delivered by ecosystems, we will show in this chapter that quantity and quality are intimately linked through the properties of the species living in the ecosystems and their behavior.