Richard Freeman, Designed Ecosystems
In this brief presentation and the presentations that follow, my mission is to introduce an approach to growing the first third of the yearly household plant produce. I emphasize the first third because it is the easiest to grow and has the highest return on investment of money, resources and labor. It also represents a big chunk of money. My mission for this brief presentation is to describe mapping and assessment, an important part of production garden design.
Just to note, my frame of reference for these presentations is an urban or suburban plot. In this scenario, space is limited so horticulture is intensive.
My presentation will follow this sequence:
1. I’ll begin by discussing some key principles.
2. Then I’ll outline a sequence of tasks required for mapping and assessment.
3. I’ll conclude by tying this presentation into the other presentations in the First Third Series.
Scale of Permanence. The scale of permanence refers to the relative permanence of any given site element. For example, paved roads are more permanent than gravel driveways and orchards are more permanent than flower beds. Generally, design and construction should begin with the most permanent elements that will be addressed and proceed towards the least permanent.
Watershed Analysis. A watershed analysis is an interesting and fun exercise that involves determining the total run-off volume of a rain event of certain duration and volume on a given site. Though it is optional for the average gardener, for someone serious about collecting rainwater for a production garden, it’s important. As anyone who has ever seen a gully-washer knows, a LOT of water can move through a small area in a short period of time.
For designing a garden, a simple visual analysis will work. A formal watershed analysis, which is pretty easy to do, depends on measuring the level area of every surface and determining how much water will run-off. The analysis refers to common co-efficients to estimate how much water will run off a given material (like sod or pavement) at a given slope and, conversely, how much will soak in. A future presentation will explain how to conduct a formal watershed analysis.
Sequence of Activities for Mapping and Assessment
Assessing and mapping a site are mutually-dependent processes that build on each other. Maps and assessments can be “back-of-the-envelope,” detailed and precise, even computerized, or any standard in between, depending on the designer’s preference or style.
I will describe the process as four steps.
Step 1. The first step is drawing (by hand or computer) a good basic outline map of the whole site – as it is – and making plenty of copies of it.
Note: be sure to scale the map to an easily workable scale. The drawing units should be easily identifiable on the ruler, and the to-scale units (on the ground) should be rounded for easy calculations. For example, 1/4-inch on the map equals one-foot on the ground (scale 1:48).
A good basic outline map includes:
- References to cardinal direction and scale, with reference to the north and scaling to feet.
- Property boundaries.
Step 2. Draw in the most permanent elements. Make a few extra copies and keep a clean copy in case you need more. If possible, print it on overlay material.
- Permanent terrain objects: hills, slopes and valleys, sharp elevation relief, rock outcrops, etc.
- Permanent built objects: houses, barns, large buildings, highways, streets, roads, paved driveways, etc.
- Water features and hydrology – ephemeral and perennial – including streams, irrigation trunk ditches, reservoirs wetlands. Make reference to seasonal variations in volume flow, heavy rain events and drainage volumes.
- Problem areas – toxic or pathogenic.
- Soil types and special conditions in reference to soil.
- Large trees, ancient trees, old hedgerows, other highly valuable vegetative elements.
Step 3. Draw in energy and material flows across and through the property. When possible, estimate volumes. Make a few extra copies and keep a clean copy in case you need more. If possible, print it on overlay material.
- Sunlight and sunshine as they change through the seasons
- Dust, air pollution and pesticides.
- Water pollution.
- Noise pollution.
- Visual pollution.
- Exposure to public view.
- Car traffic.
Step 4. Draw in semi-permanent elements. Again, make a few extra copies and keep a clean copy in case you need more. If possible, print it in overlay material.
- Semi-permanent built objects: sheds, trailer-houses, unpaved driveways and truck paths.
- Special management zones (pasture, gardens, etc.).
- Small trees, shrubs and perennial/recurring herbs, flowers and covers (including lawn grass).
- Fungi – what it is and where/when it grows.
- Foot paths.
- Fences and gates.
- Small ponds and irrigation distribution ditches.
Having created a baseline map, the next step is to clarify and state your project vision and the goals necessary to see that vision through. The next presentation, “Identifying the Project Vision and Goals,” will detail that process.