The term Biodiversity encompass 3 perspectives;
– The number of species
– The genetic diversity
– The ecosystems variations
These 3 perspectives are 3 different paradigms with different natures, epistemology and complexities.
A species is the set of animals having the capability to interbreed and give life to fertile offspring. Bacteria species definition is different because of their character asexual. Viruses are excluded as well due to their specific nature.
Genetic diversity is the variation in alleles of genes within and among populations of individuals.
Ecosystem diversity is the variation in the complexity of a biological community. It represents the largest scale of biodiversity due to its systemic dimension. Complexity emerging from the multitude of relationships between the elements, biotic and abiotic.
The main focus in Permaculture is the ecosystem diversity, the relationship between elements being more important than the elements themselves. However the design of the domestic part of the ecosystem relies on the knowledge of the species introduced or attracted taking into account their specific functions and behaviors.
The design of the domestic biologic community in Permaculture may be influenced by
– The cost, capability and quantity of individuals of a species to fit inside a specific sub-ecosystem (adapted niches and schedules)
– The number of functions and positive interrelationships a species may have within the sub-ecosystem (positive relationships includes collaboration with productive elements and competition against counterproductive elements)
– The autonomy (including breeding) of the species (reduction of human monitoring)
– The opportunities the species may bring (food or resources production)
– The architecture and the potential niches of the ecosystem
– The permeability and ecotones between the sub-ecosystems and in particular with Zone 5
In every of these considerations we must have conscience of the possible lack of knowledge and the necessity to step in very carefully every time we introduce a new species.
The mechanisms at play in biodiversity related to the species and their environment are;
– Speciation : mechanism of life differentiation through evolution. (specialization, adaptation to a niche, emergence…) Mobility of a species and time spent in a specific environment are the two predominant factors of speciation
– Extinction : due to niche change, competition with more adapted species, food chain or food web perturbation (new predators, diseases, lack of food and resources, …)
– Migrations : immigration of new species in a specific ecosystem, emigration to other ecosystems .
Here are some drives in the construction of a biologic community in Permaculture;
– Use local species (species found in local ecosystems similar to the type of climax we may direct our ecosystem to).
– Limit the organisms introduction to few individuals at start and observe the group evolution and the impact on the environment. The early identification of niches allows as well to monitor the best ratio population size / allocated area.
– Time of reactivity after the emergence of an invasive species (extinction hosting) is an important factor to consider in order to reduce future maintenance.
– By favoring the introduction of perennials plants and large elements (trees) we facilitate the control of possible invasions (e.g. competition against grass or easy management of invasive perennials due to their slowness of propagation), multiply the number of niches (3 dimensional ecosystem) therefore the number of species (speciation hosting) and introduce a factor of stability favoring species settlement on the long term.
– Permaculture farms usually gives a preponderant role to aquatic ecosystems by their capacity to distribute water, produce resources and increase biodiversity both in the aquatic ecosystem itself and through its interface (ecotone) with connected ecosystems . Water ecosystems plays an important role in wild life attraction therefore biodiversity through natural (im)migration.
– Acceptance of balance in the impacts. A recent studies showed an increase of plants health in an ecosystem after bear introduction. The animal being a predator of ants themselves impacting negatively plants through different type of fungi culture. If introducing a bear in urban Permaculture for example is maybe not the best idea other examples can be found where accepting some impact can open bigger opportunity in the global balance.
– Increase the variations inside and in between species to enlarge the scope of opportunities. E.g. Having different fruit trees species or varieties spreads production over time.
– Get inform about or test the settlement of guilds.
– Resources about the benefits of biodiversity in ecosystems functions (services) :http://en.wikipedia.org/wiki/Biodiversity#Services_enhanced_by_biodiversity