LA 250: Week 2-The Functional Landscape Landscape functions: Ecosystem functions. One of the goals of landscape design is to conserve natural systems to the extent possible. This includes such practices as using green materials, and preserving rare plants and animals. Any site, no matter how big or small, is part of a dynamic ecological landscape of interconnected parts: Biosphere: all living systems of the earth Atmosphere: gaseous envelope that surrounds us. Lithosphere: earth?s rocks and minerals. Hydrosphere: earth?s water systems. The interconnections include: Flows: one-way transfers through the system. Flows are best illustrated by the flow of energy that enters in the form of radiation from the sun, and leaves in the form of heat. Cycles: a series of reciprocal transfers, in which things are passed from one component to another (biosphere to atmosphere, etc.) or when they change states (gas to liquid, etc.), but don?t leave or enter the ecosystem. Cycles are best illustrated by cycles of nutrients such as carbon or nitrogen. Hydrological cycle: a transfer of water from the atmosphere to the earth, and back to the atmosphere. After a precipitation event, water generally filters into the soil, lands on a body of surface water, reenters the atmosphere via evaporation, or runs over the ground surface. At the scale of an individual site, water may act as a flow. Site may be a source of water for sites at lower elevations, or may be a temporary sink. One challenge in design concerns how to accommodate precipitation events. Traditional strategies aimed at removing water quickly include: moving water off of the site via pipes, sewer systems, etc. and not worry about the water once it gets off the site. This leads to problems. Modern strategies ?harvest? water: Facilitate groundwater recharge and delay discharge into lakes and streams--develop on-site storage (rain barrels, ponds, etc.) Rain gardens: a modern strategy that captures surface runoff for concentrated infiltration and allows for contaminant removal by soil and plants. Landscape designs also needs to pay attention to the ecosystem effects of adding water to a landscape, especially if the water must be imported (piped in from a municipal supply, etc.): Irrigation: pumping water from ground water supplies, causing problems. Pools and other water features cause problems if they need to be pumped from the ground. Carbon cycle? Issue? we?re worried about activities that cause increases of carbon dioxide in the atmosphere, which may lead to global warming. Goal?reduce consumption of fossil fuels in heating and cooling, and in landscape maintenance. Landscape design can: Provide shade and cool breezes in the summer. Provide sun and warmth and manage snow in the winter. Reduce the need to use power equipment. Lawn A few years ago, it was estimated that there was 25 million acres of lawn in the United States, about 40,000 miles (the size of Pennsylvania). Origins: 18th century Europe English Landscape School, a reaction to formal design. Made possible by technology?haha (an invisible, sunken fence which allows one to have a landscape with rolling hills, uninterrupted by any structure; it also allowed sheep to be fenced in, while mowing the lawn). The use of herbicides arguably increased the need for fertilizers. Lawn vs. natural forest or grassland Natural forest or grassland Lawn Nutrients largely retained on site Many nutrients leached to groundwater Net carbon dioxide output small Carbon dioxide output exceeds input Little surface water runoff Surface runoff great, carrying nutrients away Functions to provide human comfort and enjoyment: The different categories: Recreation (baseball fields, playgrounds, etc.) Working landscape (to grow plants or animals, etc.) Education (schools, zoos, etc.) Relaxation (backyards, etc.) Preservation (monuments, cemeteries, historic sites, etc.) Each kind of project has signature program elements. Circulation (getting around?pedestrian or vehicular and wayfinding?signs and directions) Seating (private or social) Amelioration of microclimate (make comfortable for all seasons of the year?shade (deciduous trees), wind, etc.) Aesthetic expression
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