Regardless of how one defines and classifies ‘ecosystem services’, as a
report from the US National Academy of Science has emphasized, ‘the
fundamental challenge of valuing ecosystem services lies in providing
an explicit description and adequate assessment of the links between the
structure and functions of natural systems, the benefits (i.e., goods and
services) derived by humanity, and their subsequent values’ (Heal et al.,
2005, p. 2). Moreover, it has been increasingly recognized by economists
and ecologists that the greatest ‘challenge’ they face is in valuing the ecosystem
services provided by a certain class of key ecosystem functions –
regulatory and habitat functions. Table 9.1 provides some examples of the
links between regulatory and habitat functions and the ecosystem services
that ultimately benefit humankind.