With the european economy being stuck under gloomy economic conditions after the banking cisis of 2008, government have been dramatically slowing their roadplan to protect the environment to leave a livable planet to our children.
In this post I would like to give a short introduction to one aspect of the environment that we should care about: the biodiversity.
→ A short definition:
Biodiversity is the contraction of biological diversity and is the variability of biological units, in its most common sense biodiversity is the species richness: the number of species found at one place. However biodiversity can also be the variation in the genes present in the environement or the number of different ecosystems. The official definition used by the scientific communities and the UN can be found here .
→ Biodiversity promotes stable and productive environement:
In the late 90’s a new field of study emerge in the ecological litterature named Biodiversity and Ecosystem Functionning (Tilman et al 1996, Walker 1992), the aim of this field was to identify the effect of plant diversity on ecosystem function, the most commonly studied one being the biomass (the mass of living material). After two decades of experimental and theoretical studies a consensus has been reached (Hooper et al 2005, Cardinale et al 2006) and now I am able to say to you that a more diverse ecosystem is more productive (higher biomass) than a less diverse one.
So what? Well this has multiple impact on all sort of orgnanism, if there is more food for the herbivores this system will be able to sustain more species with higher population sizes (see my earlier blog post on the effect of population size on species survival), more herbivores means as well more predator and so on.. Every level in the food chain will be positively affected since plant materials are at the base of every food webs.
Therefore biodiversity is good because it sustain more productive environment which lead to more diverse animal communities.
A second point is the reaction of ecosystem to environmental perturbation (like hurricanes or drought), its stability (how much perturbation is needed to affect the ecosystem) and resilience (how much time is needed for the ecosystem to return to its anterior state). Again a more diverse environment will have a higher stability a number of hypothesis are aorund to explain this (see Johnson et al 1996, Loreau et al 2013) and the debate is not yet over as to which mechanism is responsible for this effect.
So biodiversity promotes stable ecosystem.
→ Biodiversity profite to humans
In 2005 the Millenium Ecosystem Assessment came out and it has a complete part (100 pages) on the importance of biodiversity. This assessment was interested in fiding out why is biodiversity important for us humans. We are living surrounded by nature and we depend on it to provide us we the most basic things like food, air, or water. Diverse and stable ecosystem are able to provide us with these essential element of our lives. Therefore it is in our own interest that we should protect biodiversity.
The global biogeochemical cycles (carbon, nitrogen, phosphorus) are also regulated by the ecosystem, our climate and its future change will depend on the species reaction to the altered conditions we are providing them. Diverse ecosystem have by chance an higher probability to contain species or genes that will be adapted to these new conditions and will be able to carry on doing what they did (using up carbon dioxide for photosynthesis) to avoid cascading effect of climatic change.
During catastrophic event like floods, as I mentionned earlier, diverse ecosystem will be more stable, the effect of a flood will then be lowered by the presence of certain group of species (like trees). Without them the effect of these events on humans are bigger.
I hope that I have awakened your interest into this topic of biodiversity and why we should care about it, below you will find a list of litterature elements if you are interested to go deeper into this. In a future post I will go on and try to present to you how we normal/small people can care about biodiversity.
The MEA part on Biodiversity: http://www.unep.org/maweb/documents/document.354.aspx.pdf
Walker, 1992: Biodiversity and ecosystem redundancy, Conservation Biology.
Tilman et al, 1996: Productivity and sustainability influenced by biodiversity in grassland ecosystems, Nature
Hooper et al 2005: Effects of biodiversity on ecosystem functioning: a consensus of current knowledge, Ecological Monographies
Cardinale et al 2011: The functional role of producer diversity in ecosystems, The American Journal of Botany
Johnson et al 1996: Biodiversity and the productivity and stability of ecosystems, TREE
Loreau et al 2013: Biodiversity and ecosystem stability: a synthesis of underlying
mechanisms , Ecology Letters