(needs reviewing) Back to topics
Analysis: How World Works
Permaculture attempts to develop systems modeled from natural ecosystems. In order to mimic these natural systems we must learn to identify and work with the various functions of our natural resources in space and time. Ecosystems like forests are mulitple layers of vegetation growing together in a very diverse setting and successional phases. All of these components of a natural ecosystem serve a function (or several functions) that support each other (guilds).

A. Generic Analysis

    • Element Inputs and outputs: The end goal is to have a garden that requires little or no ongoing human maintenance or resource inputs. Everything that is added into the system either improves the system or degrades the system.
    • Flows
    • Patterns

B. Ecosystems Structures and Concepts in space and time

1. Spatial structures: niches, guilds and layers

Ecological niche is how an organism makes a living. The ecological niche describes how an organism or population responds to the distribution of resources and competitors (e.g., by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (e.g., limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey).
A guild is any group of species that exploit the same resources, often in related ways. Guilds are groups of plants, animals, insects, etc. that work well together.
Layers of a natural forest: canopy, overstory and understory, floor
external image succession2.gif

2. Temporal structures: succession

Ecological succession is the process by which an ecological community changes over time. Succession may be initiated either by formation of new, unoccupied habitat or by some form of disturbance (e.g. fire, severe windthrow, logging) of an existing community. This environment modifications concerns principaly soil fertility, soil moisture regime and light. Different non linear stages of succession present different productivity. Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary succession, whereas succession that follows disruption of a pre-existing community is called secondary succession. In secondary succession there is three phases: early, middle and late succession.Climax is the theoretical final stage of linear successional theory. Climax properties are: stability, self-replacement, dynamic equilibrium. Later theory present this concept as a shifting mosaic steady state.

Permaculture uses succession dynamics to influence succession in forest gardens by using different species having different life-strategies to face change. There are different categories of species: ruderal, pioneers, competitor, stress tolerator, depending on different energy allocation patterns (architectural and behavioral implications).

In general, communities in early succession will be dominated by fast-growing, well-dispersed species (opportunist, fugitive, or r-selected life-histories). As succession proceeds, these species will tend to be replaced by more competitive (k-selected) species. Species diversity almost necessarily increases during early succession as new species arrive, but may decline in later succession as competition eliminates opportunistic species and leads to dominance by locally superior competitors. Midsuccession presents offen bigger biodiversity and peaks of productivity, biomass gain, nutriment flow control and soil fertility. Net Primary Productivity, biomass, and trophic properties all show variable patterns over succession, depending on the particular system and site.

Successional change can be influenced by: site conditions, the character of the events initiating succession, the interactions of the species present, and by more stochastic factors such as availability of colonists or seeds or weather conditions at the time of disturbance. Some of these factors contribute to predictability of succession dynamics.

Phases of succession: aggrading ecosystem - disturbance (loss of infrastructure) - reorganisation (natural capital) - aggradation -transition - shifting mosaic state (gap dynamics, cycles of succession, wobbling stability) - shifting mosaics (wobbling toward stability at large scale). The gap size depend of tree species, soil, tree age and disturbance while that influence weather the pioneer trees will dominate in the case of big gaps or stress tolerants who do best in small gaps. At a small scale (5acres to 2hectares) most forested sites will not exhibit a steady state. Instead any given site in a forest will cycle continuously between disturbed condition and a regenerating condition.

Patch dynamics. Gaps, fire mosaics, lumpy texture of vegetation, windstorms, water through canopy create patches of light and dark, wet and dry. Different sized, shaped and textured patches are the fundemental units of ecosystem structure. They are dynamic and follow different successional pathway. They can be defined, managed and used as a key organizing idea for forest garden and permaculture design. The forest gardener should choose a disturbance regime in the ecosystem witch can be exploitive or distructive. The disturbance regime refers to the pattern of patches disturbance in space, in time and intensity.

The unified oldfield theory offers a theory of managing succession by managing 3 causes of succession: site or nich availability, different species availability and species performance.
It includes 6 keys to succession design 3 deal with time: horizon, scenario, phase and 3 deal with space: habitat, pattern and patch. That proposes 5 differens scenarios:
  • linear succession to an horizon (near to conventional agriculture)
  • rotational mosaics: patches succeed in circular fashion, where the right proportions of patches is important. Advantage: possibility of stable yields of diverse crops, disease prevention, soil building phase (near to biologic agriculture)
  • Gap succession: ressource patterns in gaps to design a succession within small lots surronded by trees or buildings (near to urban farming)
  • Dynamic patches: every patch has different successional pathway, by planting, disturbing, letting be and chaning goals and situations. Nice to play but not if you need to plan certain crops (near to permaculture)
  • Aikido-ing succession: observe what the ecosystem is doing and add your energy to redirect the flow. Less design and more skillfull oopportunism addapted for low productivity needs and small ressources availability (near to natural farming)


Related videos

3. Soil Life

4. Flows and Cycles: Water, Energy

5. Human and Animal Centered Zones

C. Eco-system Configurations

  • 1. Urbanity / Density : Urban life, Rural home
  • 2. Climate : Desertic, Mediterranean, Temperate, Tropical
  • 3. Local Conditions : Coast & Island, Salt

D. Ecosystem Elements

  • 1. Element Needs (Light, Water, Nutrition),
  • 2. Element Functions : Green manure, Dynamic Accumulator, Natural pest control, Structure, Soil Conditionner
  • 3. Natural forces : Sun (light, heat), Rain, Wind, Fire, Earth (gravity)
  • 4. Plants and Energy Transaction: Vegetables, Cereals, Trees, Algae
  • 5. Animals : Poultry, Livestock, Wild life, Fish
  • 6. Rhizosphere: Worms, Mushrooms & Fungi (Decomposers, Symbiotic and Parasitic), Bacteria