Some critics of invasion biology have argued the invasion of ecosystems by nonindigenous species can create more valuable ecosystems. They consider invaded communities as more valuable because they potentially produce more ecosystem services. To establish that the introduction of nonindigenous species creates more valuable ecosystems, they defend that value is provisioned by ecosystem services. These services are derived from ecosystem productivity, the production and cycling of resources. Ecosystem productivity is a result of biodiversity, which is understood as local species richness. (...) Invasive species increase local species richness and, therefore, increase the conservation value of local ecosystems. These views are disseminating to the public via a series of popular science books. Conservationists must respond to these views, and I outline a method of rejecting such arguments against controlling invasive species. Ecological systems are valuable for more than local productivity and biodiversity is not accurately described by a local species count. (shrink)

Among the instrumental value defenses for biodiversity conservation is the argument that biodiversity is necessary to support ecosystem functioning. Lower levels of biodiversity yield lower levels of ecosystem functioning and hence the inference that we should conserve biodiversity. In our book Defending Biodiversity: Environmental Science and Ethics, we point out three problems with this inference. (1) The empirical support for such an inference derives from experiments conducted on a very small set of ecosystem types (mainly grasslands and fresh water aquatic) (...) and ecosystem functions (mainly nutrient uptake, biomass production, and decomposition rates). These experiments suffer from a number of largely unavoidable logistical constraints making the generality of their results questionable. (2) Even if the experimental results were unequivocal, their lack of external validity would still raise significant questions about how (if at all) these results apply to real world conservation problems. And (3) even if the experimental results were unequivocal and completely applicable to conservation problems, relying on such defenses implies other rational policy commitments that are at odds with other positions that environmentalists commonly take. Odenbaugh and I disagree largely about what inferences follow from these points rather than about the points themselves. I think that what follows is that if environmentalists want to use instrumental value defenses, then we need to accept that not all biodiversity is useful to us, and parts that are useful are not necessarily more useful than alternatives that might threaten biodiversity. I also think that the unpalatable implied commitments need to be taken seriously. This may mean that we environmentalists have to accept that biodiversity should not always be conserved, and that parts of the environmentalist agenda are little more than strong personal preferences that others need not respect. If environmentalists are willing to accept these conclusions, then there are no problems with relying on these instrumental value defenses, but I suspect that environmentalists are likely to be unhappy with such conclusions. (shrink)

I denna artikel kommer jag att ge en översikt över olika argument som ger stöd för slutsatsen att biologisk mångfald per se är värdefullt och bör bevaras. Ett vanligt argument vilar på premissen att biologisk mångfald har egenvärde, men premissen är svår att göra rimlig och får lätt kontraintuitiva följder. Utöver det kommer jag även att kritiskt granska instrumentella värden, relationella värden, och vad som här kallas ’miljöspecifika’ värden. I den sistnämnda kategorin ingår begrepp som naturlighet och naturvärde. Dessa definieras (...) ofta med ’frånvaro av avsiktlig mänsklig påverkan’ som ett nödvändigt villkor. Det kan finnas goda skäl att nyansera såväl instrumentellt värde som definitionen av naturvärde för att tillåta mänsklig påverkan som främjar biologisk mångfald utan att en värdeminskning sker. (shrink)