Abstract

The term ‘ecosystem services’ has been around since at least the 1970s, and the concept of Nature providing for human needs even longer (Gómez-Baggethun et al., 2010). However, only relatively recently have ecosystem services started to become included in practical policy appraisal and decision-making. The motivation for this has come largely from an acknowledgement of the value of the natural capital locked up in ecosystems not only for providing market goods but also for underpinning the delivery of a range of benefits for which there is no market and which are difficult to monetise and therefore have little or no value attached to them (e.g. Costanza et al., 1997; Daily, 1997; Stern, 2006; TEEB, 2010). In addition, it is now unarguable that the processes involved in the extraction of goods leads to declines in other services, biodiversity in particular (MA, 2005). Whilst it is clear that levels of natural resource stocks (natural capital) will affect the flows and values of both goods and services, the linkages between stocks and flows are complex (Daly and Farley, 2011), so that the integration of this knowledge and these concepts into practical environmental management and decision-making has proven challenging. Estimating changes in the rate at which services would be delivered (their flow) under different policy options, and whether this is sustainable given the levels of various ecosystem components that generate those services (natural capital stocks), remains a thorny problem for practical ecosystem ecologists and is the focus of considerable research effort world-wide (e.g. the VNN and BESS research programmes in the UK). This chapter clarifies some of these challenges, specifically the concepts of stocks and flows in an ecosystem services context, how both stocks and flows might be evaluated and monitored, and possible ways forward for a more holistic, integrated approach.