IC H A E L
P H O T O G R A P H
to conserve plant species with material wealth has obvious attractions, but other values of plant diversity are also important. Some people also argue that consideration of monetary value is dangerous talk, which detracts from more valid ethical and biological arguments. They say that species have an intrinsic right to exist irrespective of their value to humans.
It is important to realise the difference between biological resources - basically the ‘amount’ of life on earth - and biological diversity (biodiversity), which is the amount of variety within that total amount. Biodiversity includes the natural variation between members of the same species (different flower colours, perhaps, or geographical variations); the differences between one species and another; and the differences within different habitats. Putting a financial value on biodiversity is far harder than putting a financial value on biological resources. You can make a pretty good guess at the value of the timber in a pair of oak trees, but how much difference does it make if the trees are the same species or two different ones?
The financial value of plant commodities such as timber and the world’s major food crops, contributes directly to national economies, and trade statistics are readily compiled. But the contribution of biodiversity to this has more to do with the value of being
The Mediterranean garrigue is a semi-natural habitat with a rich diversity of endemic flora able to introduce new crops or varieties, than the value of the resource as a whole. It is also difficult to account for the many plants consumed as food around the world which have no financial value at all, because they are taken directly from the wild and eaten locally without entering trade.
Indirect values, known as ‘non-consumptive values’, of biodiversity are even more difficult to measure. Ecological services, for example, which include such vital processes as maintaining water supplies, the prevention of flash flooding, regulation of climate,
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