Permaculture Designers Manual
CHAPTER 5 – CLIMATIC FACTORS IN PERMACULTURE
Section 5.10 –
Chapter 5 Designers’ Checklist in Permaculture Designers Manual
Check data on average rainfall, temperature, and wind speed and direction for the region (often found by contacting the Bureau of Meteorology).
Ascertain the general “hardiness” zone for plants and animals. This is based on temperature, with frost being the limiting factor. Make a survey of the plants that grow in the area, noting special circumstances surrounding plants that are “marginal”; w hat is the technique or microclimate that allows them to grow?
Find out about flood locations and periodicity, rain intensity, temperature extremes and the seasonal rainfall pattern. Allow for extremes (e.g. no rain in summer) when designing.
Consider total precipitation (snow, hail, rain, log, condensation and dew) so that your design can include ways to trap and store moisture (dry climates) or ways to dispose of too much moisture (wet climates).
Consider light availability, especially on foggy coasts; light becomes the limiting factor for flowering plants.
Continental climates mean more temperature extremes, while maritime climates buffer severe heat or cold.
Altitude effects: approximately every 100m of altitude is equivalent to 1° of latitude, so that a variety of plants can be grown if the property contains hills and flats. In the sub tropics, even temperate area plants can be grown on high islands or hills.
Note where frost is produced (in hollows, on flats, and on large clearings) and where it is absent (the “thermal belt” on hills, under tree canopies).
Note tree flagging on the site; this shows the direction of persistent winds (although winds, sometimes severe, may blow from other directions). You can put tall stakes with colored cloth or plastic streamers at different locations and observe them seasonally. (Figure 6.2)
For accurate temperatures, you can have several maximum/minimum thermometers in different locations. These thermometers record the highest and lowest temperatures reached during 24 hours, and are helpful in locating microclimatic areas such as thermal belts (if on a sun-facing slope), cold drainage areas, and frost hollows.
Site the house and garden on the thermal belt if possible.
In minimal frost areas, plant light-canopy trees in the garden for frost protection (tree canopies help keep rapid cooling of the earth to a minimum). Or plant into a steep-sided clearing or pit.
In houses, design so that you use light and radiation to best effect, particularly in temperate climates. Particular use should be made of the thermo siphon effect of heat, so that heat sources are placed below storage and use points.
Use the principle that white reflects, dark absorbs, heat. Plant shrubs and trees, needing heat and light, in front of white-painted walls.
When planning windbreaks, consider:
Trees that give multiple function, e.g. mulch (Casuarina), bee nectar (dogwood), sugar pods for animals (carob. honey locust), edible leaves Leucaena, tagasaste), berries for poultry (Coprosma repens, Russian olive).
The windbreak planting itself may need initial protection and care (nutrients, water, weeding. or mulching).
If the winds are very severe look around the area to see what stands up to it, and plant it whether it provides multiple function or not. Plant more useful plants in its lee. Protection includes fencing, earth banks, tire walls, etc.
Choose a windbreak configuration that is effective for the particular design situation. In tropical and subtropical areas, a thin-crowned windbreak in crop can be used to advantage, providing shade and mulch for vegetable crop.