Last week we discussed some anthropocentric drivers that contributes to biodiversity loss today. In recent 50 years, human have changed ecosystem more rapidly and extensively than in any comparable period of time in human history. For example (MEA, 2005), 35% of mangrove area has been lost in the last several decades, coral reefs have degraded by 20%. According to living planet index, all vertebrate species fell by 40% as a whole, with terrestrial species fell by 30%. Living planet index is based on large time-series database on vertebrate population trend indicators to track the abundance of wild animals. Yet it has the disadvantage that the selection of species, the averaging method and chosen species baseline all influence the species trend indicators (Vackar, 2011). There are currently other existing indicators (and in the future we will compare some of them in my blog), but living planet index is the most commonly adopted as a campaign tool because it is easy to understand.
But the question is, why should we care?
According to the Millennium Ecosystem Assessment report (MEA, 2005), biodiversity is the key element in maintaining ecosystem services, including supporting services, provisioning services, regulating services and cultural services. Supporting services is fundamental services delivered by plants and microorganisms, like nutrient cycling and photosynthesis. Regulating services include climate, water, soil erosion regulation, pollination and etc. Provisioning services are mainly for human physical utilisation such as food, fibre,and fuel. Cultural services are not non-material benefits, or spiritual/aesthetic purposes of human resource utilisation. With biodiversity loss, these functions would be severely weakened. One case study would be the colony collapse disorder, which is caused the large-scale application of pesticide in agricultural land. This leads to a disorder function in the bee community with a loss of pollination function. From human perspective, it directly caused economic loss and resource waste.
Yet is there a difference in terms of biodiversity importance of different species? Ethically there should not be any as every species has their inherit value. The inherit value of animals is raised by Arne Naess in his deep ecology movement, and was accepted in the Rio Convention on Biological Diversity 1992. However, from the ecosystem perspective, there is a difference in biodiversity importance among different species. Large mammals usually have disproportionate effects on the ecosystem, as large carnivores have a top-down regulating role in community structure, and large herbivores play as ecological engineers. Large carnivores directly regulate herbivores and mesocarnivores, and there would be a cascading effect if the top predator is lost. One example is the decline of wolf in Yellowstone leads to an increase of the mesocarnivores in Yellow stone national park and leads to the imbalance ecosystem status of the park. This is a classic ecology textbook example, yet different voices are found recently, suggesting that the restoration of the ecosystem is temporary, and wolves will lead to new changes in local biodiversity (Smith et al., 2003). In the meantime, large herbivores play the role of ecosystem engineer (Jones et al., 1994), as they regulate the availability of resources by physical state changes in biotic and abiotic materials. Hence large mammals are more ecologically important than small mammals in terms of ecological importance. Also from anthropocentric perspective, large mammals bring more economic benefits (tourism) and is frequently related to local culture (e.g. tiger is the totem of ethnic minority group in northern China).
But even some species are more important than others, that does not mean there shall be a discrimination. Instead, conservation efforts shall be adopted in holistic management strategy and adjusted according to local conditions. In a word, biodiversity is important to human being, from fundamental surviving necessity to human well being.
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