Species contributions to single biodiversity values under-estimate whole community contribution to a wider range of values to society.

The valuing of biodiversity for human benefit has become an important principle for those involved in making strategic decisions about the management of natural resources.  For example, the economic contribution made to agriculture by pollinating insects has been recognised as delivering an ecosystem service; these pollinating insects can be considered as having an economic or utilitarian value. Various international initiatives have acknowledged the importance of valuing biodiversity in different ways, from the utilitarian value just mentioned through to cultural value and conservational value.

There is, however, a need to understand just what ‘valuing’ biodiversity or species really means, and to determine which species within a community contribute to which values and to what degree. Few studies have attempted to score species objectively across the different ways of valuing nature and biodiversity, so this paper – which looks at farmland birds – provides some valuable insight.

Gavin Siriwardena and colleagues looked at 38 farmland bird species and assessed their relative contribution to a number of biodiversity values, reflecting the amount of economically important weed seeds they took in their diet (utilitarian value), their occurrence in poetry (cultural value) and their relative rarity and population change (conservational value). The results of this work indicate that looking through the lens of just a single biodiversity value would underestimate the farmland bird community’s contribution more generally.

By being able to quantify the contributions of individual species it becomes possible to determine the number and identity of those species contributing to specific services and values, and to reveal potential synergies or trade-offs between multiple values. The study found little evidence that species prominent in providing one value also contribute strongly to others, something that underlines the need to examine multiple values rather than just one when assessing biodiversity benefit.

Where different biodiversity values can be assessed in this way, and made more transparent, it should deliver a more complete picture of the diverse ways in which biodiversity can be valued, and make for better informed decision making.