Posted on | March 25, 2010 | No Comments
Continental climates are influenced by their geographic position being a large distance from the moderating effect of an ocean. Typical effects are a large variation between high summer temperatures and low winter temperature. The main usual come at the change of season spring and autumn.
Orthographic effects are common where climate is distorted by landscape form; these effects can be quite dramatic and will always need to be taken into consideration.
Ecosystems are climate moderators stabilizing the global weather systems. With the majority of the Earth’s ecosystems removed and the remainder under severe imminent threat of destruction, the global climate has become unstable and erratic. We are now experiencing a global climate system out of sync, with the hottest, coldest, wettest, driest, windiest event possible everywhere at once at any time of the year, possibly the fastest extreme rapid climate change ever. In this situation, we need more than ever before to be able to design and implement agriculturally productive ecosystems, which have the diversity, stability, resilience and flexible dynamics of natural ecosystems.
The Humid Landscape:
Humid landscapes of the tropic or temperate are gently rounded due to the forces of regular water on the substrate. This classic profile decides our whole strategy in water, structural and access placements, forests, soils, frost, fire and crops.
These are collection areas for rain, mists and humid air. Wide bald ridges can make good grazing country but narrow steep ridges should always be forested. Collection of water is possible with ridge point, plateau edge and saddle dams, with extra water harvesting features of swales these work extremely well.
Instability of soils if greater than 18 degree slope or less in fragile soils is cleared of forest. Forest is the stabilizing mechanism for steep slopes and fragile soils. Forest work as warming systems for cold air flows. Water collection in plateau or contour dams is possible in the appropriate landscape profile.
This is a critical water point for lower slope irrigation and occurs near the top of all valleys in the humid landscape. Diversion drain can run into the key point, swales can run out to the ridges from the key point. Cultivation possible below the key point, water is clean above the key point and can be soiled with organic material below, beneficial for fertilization through irrigation. Housing is best suited to below the key point with forest above.
Suited to mixed cultivation poly-culture. Terra forms include terraces or mini-terraces.
Treatment of Individual Slopes:
Steep slopes with hard degraded soils or stones can be recovered using a net and pan small earth works and pioneer tree planting system.
Steep grassy slopes can be forested with pioneer trees using well mulch planting shelves. Small, free-ranged animals, cycled through as required, speeds up the process.
Very steep slopes are only possible to cultivate with very accurately constructed classical intensive terrace. Fire control needs careful design. Mini-catchments can be defined and captured to establish pioneer trees to stabilize slopes.
Gravity irrigation techniques are usually passive with low head pressure and they need careful planning. Check dams back up a low head of water, as a great asset for irrigation in flat lands. Mulch is essential for growing systems and establishes pioneer tree windbreaks which can latter be themselves become mulch producers, and protection for crops and fruit trees. Swales on the flat country intercept run-off water which builds up local ground water reducing the need for extra irrigation. Earth banks add extra form, features and functions to the flat landscape.
The Arid Landscape:
An important desert strategy is to have many little systems going at once, all design to catch and store water. Water must be stored in the ground or underground away from the evaporation of the Sun. The placement of human habitation in relation to access to water, shade and cooling effects of winds all need careful consideration. Shade and shade houses are extremely value attachments to structures for comfortable living environments. All wastewater should be directed underneath mulch in home gardens for production and evaporation efficiency. Animal housing needs to be situated so that accurate control of their manure and its flow through the system can be achieved. Check dams across seasonal flows of water allow for flood flow irrigation, and low swale earth banks soak water into landscape. Mulch traps on water flow, and is also trapped by windbreaks as they comb the airflows of fine soils and organic matter. Roads and all man made hard surfaces need to be designed to direct run-off water for productive purposes. In stone deserts stone swales and earth backed stone swales hold back run off water long enough to soak in and create freshwater lenses in soils. Rock gabion dam walls leak water through but back fill with silt, which holds water and stays wet for long periods after rains. They also stop the movement of rocks and boulders which pile up at the top end of the silt pool unable to roll across the level surface. Woven baskets and large cardboard boxes can be used to plant trees deep in sand dunes, where sufficient moisture for growth is usually found one meter down.
Landscape features of the desert are numerous especially erosion forms which are very conspicuous and significant. The true desert has a broad classification of sandy desert, sand plains with several types of dunes, Hamada rock and boulder pavement, and gravel surfaces where sand and silt have been removed. Generally the desert landscape is distinctly angular and actively eroding.