The Edge Effect Principle
The tenth Permaculture principle, 'Edge Effect,' aims to increase our systems' biodiversity and productivity by emulating the 'edge effect,' a natural phenomenon, and its patterns.
To grasp this design principle, we will first look at how Permaculture design utilizes edge effects, then examine how we can use Nature's patterns to enhance the efficiency and productivity of our systems.
Edge Effect - Explained
Let's define a few ecological terms before we discuss them. An edge effect is an ecological description of how more variety of life is found at the boundary between two ecosystems that overlap, such as land and water or wood and grassland. While standing at the boundary of two overlapped ecosystems, you may see a range of species from both ecosystems and specially adapted animals that are not present in either ecosystem but can thrive in the transition zone.
An edge is an interface or boundary between two distinct landscape elements (for example, land and water) or between ecosystems (for example, forest and grassland).
An ecotone is a transitional region where two distinct ecosystems meet (for example, a forest-meadow interface). The blending of ecosystems may occur in a relatively smooth or extremely abrupt fashion.
Many ecosystem boundaries have edge environments, some of which are:
Adjacent to bodies of water, such as rivers, lakes, and streams.
Forests adjoin rock outcrops, riparian zones (i.e., stream banks), and meadows.
Along outcrops of exposed rock and cliffs
Where forested areas border clearings
Abrupt variations in soil type or hydrology might exist.
Where the estuary meets the sea.
When two ecosystems overlap, the ecotone (the region where the edges meet) has a higher species diversity than either ecosystem alone. It has higher productivity because it supports species from both plus one species exclusively found there. Because of the following reasons, ecotones have higher productivity than either ecosystem alone:
Both ecosystems' resources can be accessed in one place.
The levels of air temperature, humidity, soil moisture, and light intensity all vary at boundaries.
Unique species may be supported by favorable microclimates formed by variations in conditions at the edges.
Greater plant diversity and productivity can be supported along plant edges, where light is more abundant (increased availability).
An increase in plant diversity increases the number of herbivorous insects, increasing the number of birds. In turn, the increased number of birds attracts more predators.
Large amounts of materials, nutrients, and energy are captured as they move across ecosystem boundaries and edges—for example, leaves and soil are blown against barriers, shells accumulate on the beach, etc.
The flow of energy, materials (nutrients), and organisms between ecosystems adjacent to one another can strongly influence the productivity and fertility of ecosystems.
The edge effect in Nature indicates that the environmental conditions at the boundaries of ecosystems differ from those within them. Mangrove and coral reef ecosystems (marine/terrestrial interfaces) are some of the most productive natural habitats and riparian habitats (the banks of rivers and streams). Biodiversity is exceptionally high in these regions. Human societies are historically located at the intersection of various ecosystems, including rivers, estuaries, and oceans, the borders of forests, hills, and plains.
An edge is an ecosystem interface through which one ecosystem is connected to and interacts with another. All ecosystems are part of a web of life, just as all things in Nature do. This idea is conveyed in the following extract:
"…ecosystem ecologists realized early on that ecosystems are open systems in which living and nonliving matter and organisms move about and that ecosystem dynamics could not be understood unless ecosystems were regarded as open systems. Their research demonstrated how ecosystems function as highly interlinked networks by tracking the exchange and storage of 'common currencies' such as nitrogen and organic carbon as they moved across system boundaries."
You can use Edge effects in design in a variety of ways.
We have seen how edges serve as the interface of ecosystems and how these borders are more productive and rich in life. In Permaculture design, this means that:
There are more beneficial relationships between the elements at the edges.
Because they are the hot spots for material and energy flow across ecosystems, edges are characterized by increased material and energy cycling.
Edges create beneficial microclimates.
The ecosystem's edge supports the production of biomass and biodiversity.
We can enhance the performance of our systems by capitalizing on the 'edge effect,' a natural phenomenon. By expanding the edge available in our systems, we can do this. We can accomplish this by copying the patterns of Nature in our designs.
Throughout hundreds of millions of years of evolution, Nature has become as efficient as possible. Intriguingly, Nature does not utilize straight lines; instead, Nature utilizes a variety of patterns that repeat throughout.
Let's examine how Nature creates patterns to help us arrange elements more efficiently.
All life forms in Nature employ the same patterns, which are there for efficiency rather than aesthetic purposes. Because Nature has figured out how to pack as much as possible into small spaces and organize things efficiently, these patterns are utilized. Surface areas in many natural systems that engage with the surroundings are maximized through edge patterns.
Crenelated or Lobular Patterns
A wavy edge provides more edge than a straight line, whether crenelated (indented with square sides) or lobular (having small lobes). By meandering through the landscape, rivers increase the water penetrating the land and consequently enlarge the riparian ecosystem, compared to running in a straight line.
The pattern found in the macrocosm is also present in the microcosm. Namely, our intestines twist similarly to maximize surface area and absorption of nutrients.
We can still go deeper into the microcosm and find the same patterns. Mitochondria, tiny organelles found in every eukaryotic (non-bacterial) cell, are small structures within cells. Animals are the primary energy producers, converting oxygen and nutrients into energy. Aerobic respiration, the conversion of oxygen and nutrients into energy, is why animals breathe oxygen.
Mitochondria, the 'power generators' in living cells, have wavy patterns in their inner structure. We can maximize the available edge by replicating this pattern in our designs. For example, we may double the length of the edge (the earth/water interface) on a pond without altering its size. Twice as many plants may be placed around it as a result. For example, 100 square meters of the water surface can be created by establishing an 11.3-meter circle and doubling the effective circumference by changing the edge from straight to wavy.
To make the most of our garden beds, we can utilize the same principle in path design. The wavy path through the garden allows us to plant more along the edges and have more space to walk through the garden. A keyhole bed enables us to access the beds without stepping into the soil, avoiding soil compaction and hindering plant growth.
The same idea can be used at the next level, from garden beds to the actual planting layout within the beds, to optimize space use and increase yields.
Edge Cropping is a technique in which two crops, such as wheat and lucerne, are alternately planted in rows. The lines can be arranged in wavy patterns to maximize space usage and increase plant quantities per area.
Strip intercropping, in which several crops are grown in narrow, adjacent rows, allowing for interaction between the species but for modern equipment management, is a contemporary modification of the intercropping system. Rather than growing just one crop per field (sole cropping), intercropping allows for less resource competition between species. Sole cropping (growing just one species per field) creates more competition among the same species. Throughout history and worldwide, intercrops have matched better crop demands to available sunlight, water, nutrients, and labor.
You might also like: How to Plant Trees In Your Backyard.
More than just lines, edges can be of any shape:
A fence with a zigzag pattern is more wind resistant and less prone to being blown over.
Pitted edges, similar to waffle iron, can be used in dry climates to trap wind-blown debris, organic matter, water, and seeds.
Maintaining areas can be accessed gently by contour-following paths that gently cure the path.
Sharply curved boundaries can protect plants from the wind and maximize heat to create a 'sun trap.'
Spirals are a common occurrence in Nature, and this shape can also be utilized to enhance the quantity of productive edge we have to work with.
When we employ a spiral pattern in our work, we employ it in three dimensions so that it might rise into the air rather than remain flat on the ground.
The most typical application of this design technique is a Herb Spiral that provides us with multiple microclimates, providing another benefit.
The side facing the sun is warmer, and the mound acts as a thermal mass, favoring sun-loving herbs and ones which need more heat.
Herbs that prefer shade live on the shadier side of the plant, opposite the sun.
Herbs that prefer dry conditions benefit from the top of the herb spiral, where water drains away more quickly
Herbs requiring more moisture can thrive at the base of the spiral.
A single structure can help us grow vertically to increase the available edge, increase yields and productivity, and create visual interest in our garden space by creating multiple microclimates.
An increase in edge area in our designs enables us to connect to the surrounding ecosystems and catch more material and energy as it moves through our systems, resulting in higher yields and productivity. Edge structure can be rather diverse. For example, it can be wavy, lobular, crenelated, zigzag, or spiral. Elevated mounds function as edges to increase plant yields and create wind protection, improved drainage, and various microclimates.
Selecting the right kind of edge pattern is crucial for our environment. Different systems require distinct approaches, and we must consider landscape, scale, climate, and plant species when choosing an edge pattern. Small-scale systems may support more pattern complexity, while large-scale systems should be simple to minimize maintenance time.
In addition to being more natural and aesthetically pleasing, our gardens can now be more efficient thanks to Nature's patterns.
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