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Why ecological landscape design requires intimate local climate knowledge

“When we try to pick out anything by itself, we find it hitched to everything else in the Universe”.   John Muir. Conservationist.

If we wish to create ecologically sustainable landscapes, learning to work with local climate conditions is essential.

To design ecologically sustainable landscapes, we have to try and understand how living and non-living things in a landscape connect to and influence each other. This requires us to develop an intimate knowledge of local climate, weather and soil conditions, and how local plant and animal life respond to these and to each other.

Climate affects soil conditions, what types of plants grow in an area, and how plants grow.  It  can also influence animal behaviour. Although, individually, we cannot change general climate conditions, the way we manage a landscape can influence how climate affects our farm or garden.

In broad strokes, these are some of the challenges various general climate conditions pose for landscape managers.

Moist Tropical and Sub-tropical regions

Challenges

  •  High humidity, heat, and high rainfall cause rampant plant growth that can be difficult to manage.
  • Organic matter decomposes quickly, and high rainfall leaches soils of nutrients.
  • Soils can quickly become infertile if lost organic matter is not regularly replaced.
  • Heavy rainfall may cause water logging and soil erosion.
  • Rainfall is not always predictable. Drought and long dry periods can occur.
  • Wind may cause problems.
  • Heat and humidity can create uncomfortable conditions.
  • Pests and diseases may be pervasive and problematic. 

Solutions

  • Regularly replenish soil organic matter with mulch, compost or green manures.
  • Practice poly-culture to reduce soil nutrient loss and help control pests and disease.
  • Plan suitable drainage for wet periods, such as freely draining raised beds.
  • Use dry-land gardening methods to cope with drought and dry periods.
  • Use climate appropriate architecture and planting to cool the atmosphere, create cooling shade, and make the most of warm winters.
  • Design natural methods of pest management into the garden to reduce reliance on pesticides.

 *Note, Cool sub-tropical climate may share some of the same challenges as warm temperate climates, and some tropical and sub-tropical regions suffer dry, arid and semi-desert conditions.

Dry-land, arid and semi-desert regions

Challenges

  • Rainfall is less than 700mm a year, or is very erratic or seasonal.
  • Evaporation is high and humidity is low.
  • Temperatures may vary wildly between seasons, and between day and night temperatures.
  • Temperature extremes are common and can cause heat stress, sun scorch and cold damage to plants.
  • Winds may be frequent, damaging and drying.
  • Soils are often humus poor and don’t hold water well.
  • Soils often erode easily through wind and water action.
  • Organic matter decomposes slowly, leading to poor soil fertility, low humus levels and low soil microbial activity.

Solutions

  • Use wind breaks and appropriate protective landscaping to provide wind, cold and heat shelters.
  • Create sheltering swales, depressions, mounds, walls, rock shelters, hedges, wind breaks and sheltering overhead structures and xeriscaping (water wise landscaping techniques) to build up a moisture retentive micro-climates.
  • Build up mulch and soil humus to retain soil moisture.
  • Use compost teas and micro-organism teas ( EM) to aid decomposition
  • Capture and conserve as much water as possible by clever ground contouring, through water harvesting and storage facilities, by building up the moisture holding capacity of the soil, and by recycling water.
  • Grow water wise and drought tolerant plants that can cope with the extreme climatic conditions.
  • Cover bare earth with plants, mulch, gravel or other suitable forms of ground cover to protect roots against heat and cold, and to prevent evaporation.
  • Use nurse plants to shelter more sensitive varieties. Nurse plants are hardy varieties of quick growing plants that can be planted to create shelter belts for more sensitive varieties.  

 (See also my blog post Plan a drought resilient landscape. http://www.linkedin.com/pulse/plan-drought-resilient-landscape-valerie-payn?trk=mp-reader-card

 Moist, temperate regions

 Challenges

  • Average rainfall levels are high, but rainfall may be highly seasonal. In the wet season it can be very wet, and in the dry season, very dry.
  • In the rainy season water-logging can be a problem.
  • Lack of water can be a challenge in the dry season.
  • Evaporation rates in the dry season can be high. Humidity can be intense in the wet season
  • Temperatures may change considerably between seasons. Gardens may be very cold in winter and hot in summer.
  • Drying or freezing winds can be a problem.
  • Plants may suffer from wind, frost, snow, and heat damage at different times of year.
  • Heavy rainfall can cause soil nutrients to leach away quickly.
  • In the wet season soil can suffer high, quick losses of organic matter.
  • Decomposition rates in the dry season is slow, so organic matter build-up is limited.
  • Soil building microbes can become inactive in very cold or very dry periods, affecting soils fertility.

 Solutions

  • Use aspect wisely to create a landscape micro-climate that stays warm in cold winters, but cool in hot summers. (Aspect in the way sunlight and shadow affect the landscape)
  • Mulch and compost liberally to maintain soil humus levels.
  • Build wind breaks to protect against drying or freezing winds
  • Use dry-land landscaping techniques to conserve and prevent moisture loss in dry seasons.
  • Use nurse plants, shelter belts, and succession planting to create micro-climates that protect tender plants against wind, frost, snow or heat damage.
  • Allow adequate drainage to prevent soil becoming waterlogged in wet seasons.
  • Choose plants that can survive the seasonal extremes of temperature, humidity, wet and dry conditions.
  • Respect the cyclical nature of temperate landscapes and enjoy the variety of four distinct seasons.
  • Plan your landscape activities to be season appropriate.

Becoming intimate with the effects of local climates can be challenging, but also fascinating. Topography (the lie of the land), aspect (how sunlight and shadows affect the landscape) and other factors mean local climate conditions may vary quite considerably, even within the same region.  .

The new website Combiculture ( http://combiculture.com/ )  hopes to make this task easier by building up a data base of shared experience and knowledge of climate, companion planting, and soil conditions around the globe.

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