Understanding Ecosystems - and Why Your Lawn is Just a Baby

by: EJ on 11/16/2016

Understanding how ecosystems work is essential to sustainable living.  Let's be clear, these are real ecosystems -- the interaction between living organisms and their natural environment.  Not the co-opted ecosystems of internet connections.  The following excerpt from Ross Mars’ new book, The Permaculture Transition Manual: A Comprehensive Guide, gives a succinct description of what an ecosystem is and how it works.

bidiversity

An ecosystem is a collection of interacting organisms and their surroundings. A forest ecosystem, for example, would include all the plants and animals that live there and their interaction with their physical surroundings. Ecosystems are dynamic. They change as species move in and out, the types of plants change over time, and the soil also changes. All of this results in continual disturbance, which drives the nutrient cycles and interactions within the ecosystem. This continual change is called succession.

Ecology succession takes disturbance, just like most things in life. We need to provide or undertake the right amount of disturbance and disruption to enhance biomass productivity. Disturbance even on a vulnerable and fragile landscape can ultimately result in successful healing of the land. This may include installing dams to harvest rainfall and thinning trees to increase light penetration to a forest floor and to the soil. While nature uses disturbance in successional changes in ecosystems, we can use disturbance in appropriate ways and at appropriate times to be innovative. On the other hand, too much disturbance can result in weeds and soil damage so it is an art to get that right balance. Provided there is enough rain or irrigation, succession drives a landscape towards forest. Landscapes tend to be patchy as disturbances (fire, storms, even clearing) always occur and interrupt the successional process. New bare ground becomes covered by weeds.

gardenrows

The whole significance of this is that when we garden — plant our vegetables, flowers or other (useful) plants — we are essentially planting pioneers and creating a patchwork of mini-ecosystems all at different stages. Furthermore, as we change our soils from clays and sands to loam, full of organic matter, weeds tend to become less prolific. You may still get weeds but the type of weed changes. For example, capeweed (Arctotheca calendula) and Patterson’s curse (Echium plantagineum) are common in calcium-deficient and infertile soil, but as we build healthy soil these very unwanted plants are replaced by fat hen (lamb’s quarters, Chenopodium album) or other  “weeds” that are indicators of fertile soil. It is quite clear that succession, for want of a better or possibly more appropriate term, occurs in soils too.

In essence, ecologically speaking, our backyards, which we enthusiastically tend and maintain, just want to grow up. So permaculture has always promoted the planting of the large climax, perennial trees and shrubs, as well as our annual vegetables. We strive to create a mature woodland or open  forest, or even a rainforest in that climatic region, but what we end up doing in our backyards is more akin to a very young ecosystem that is never allowed to fully develop.

FoodForest

We install plant systems as a selective diversity — we determine what trees and shrubs we should have in our gardens, and in some cases this ad hoc combination may only work poorly, even with our aspiration of a “food forest” in the backyard. As we continually harvest and remove edible plants, the many garden beds always remain ecologically unstable.

Once we understand all of this, we can implement more complex ecosystems. We can use different parts of the garden to create microclimates for the optimum growing conditions for particular plants.

sundirection

Developing microclimate regions in our gardens is driven by the sun and heat. The soil heats up, light and heat are reflected, heat causes winds, and warm water evaporates and increases humidity. In turn, plants that survive further contribute to the local environment — creating shade as they grow large, now reducing the air temperature even more, reducing evaporation from the soil, and new habitats  are formed. It’s like the analogy of the woodland becoming the rainforest. Permaculturalists should all become familiar with microclimate gardening as this is the key to successful guilds (see page 23)  and successful production, as well as moving the garden to maturity.

Unfortunately, our annual vegetables are fast growing and productive, and then harvested typically within a year. The ground is prepared and another crop sown.  When we have fruit and nut trees and other perennial plants, such as herbs and companions, then our gardens go through a disjointed successional phase. Perennials continue to grow and spread but annuals are replaced. Gardening like this, unfortunately, cannot be helped if we want to grow food. It is possible, of course, to grow more perennial vegetables, but this can limit our variety of foodstuffs. Most people don’t want to only eat  the same vegetables all the time, so seasonal variation is preferable.

 

THE PERMACULTURE TRANSITION MANUAL  IS AVAILABLE FOR PURCHASE HERE

 

 

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