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| About the Catchment Area : Plants and Animals Ecosystems Their complexity and dynamism contribute to their productivity, but make them challenging to manage. We are intimately familiar with ecosystems. They are the woodlands where we live, cut timber, or hike; the lakes, creeks, and rivers we fish, boat, transport our goods on, and tap for water; the rangelands where we graze our cattle; the beaches where we play, and the marine waters we trawl; the farmlands we till; even the urban parks and green spaces we stroll. In effect, every centimeter of the planet is part of an ecosystem. When talking about ecosystems, the matter of scale or size is important. A small bog, a single sand dune, or a tiny patch of forest may be viewed as an ecosystem, unique in its mix of species and microclimate-a microenvironment. On a much larger scale, an “ecosystem” may also refer to much more extensive communities-a 100 or 1,000 km square forest, or a major river system, each having many such microenvironments. Information about ecosystems sourced from: World Resources 200-2001, People and Ecosystems: The Fraying Web of Life, Web Address - http://www.wri.org/wr2000/pdf.html Why care about ecosystems? Ecosystems sustain us. They are Earth’s primary producers-solar-powered factories that yield the most basic necessities: food, fiber, water-and all at an efficiency unmatched by human technology. Ecosystems also provide essential functions-services like air and water purification, climate control, nutrient cycling, and soil production-that we can’t replace at any reasonable price. Harvesting the bounty of ecosystems roots our economies and provides us employment, particularly in low- and middle-income countries. Agriculture, forestry, and fishing are responsible for 50 percent of all jobs worldwide and 70 percent of the jobs in sub-Saharan Africa, East Asia, and the Pacific. In 25 percent of the world’s nations, crops, timber, and fish still contribute more to the economy than industrial goods. Global agriculture alone produces $1.3 trillion in food and fiber each year. Ecosystems feed our souls as well, providing places for religious expression, aesthetic enjoyment, and recreation. Every year, millions of people make pilgrimages to outdoor holy places, vacation in scenic regions, or simply pause in a park or their gardens to reflect or relax. As the manifestation of nature, ecosystems are the psychological and spiritual backdrop of our lives. In every respect, human development and human security are closely linked to the productivity of ecosystems. Our future rests squarely on their continued viability. Information Source: World Resources 200-2001, People and Ecosystems: The Fraying Web of Life, Web Address - http://www.wri.org/wr2000/pdf.html Ecosystem Services The functioning of natural ecosystems provides services essential to human survival. Collectively, these services maintain the Earth in a state that can support life. Ecosystem services maintain the atmosphere, provide clean water, control soil erosion, pollution and pests, pollinate plants, and much more. Their total annual value in Australia has been estimated by the CSIRO to be $1327 billion and they are free! Consider the atmosphere. Terrestrial animals need air with the correct balance of gases, which includes at least 20% oxygen. Oxygen is provided by plants and algae through photosynthesis. So clearing vegetation and polluting the ocean may threaten the very air we breathe. Water is also essential for survival. The water cycle of rain and evaporation is partly controlled by vegetation. For example, forests can affect entire regional climates because they pump enough water from the soil to the air, causing more rainfall. Large-scale deforestation could cause serious drying of regional climates. The transpiration stream of trees keeps the water table down, but only if there are enough trees. This prevents the salinisation of topsoil, already a huge problem in the mostly treeless Murray-Darling farmlands. Vegetation also controls soil erosion, which is another huge problem. Every year, over 20 billion tonnes of the Earth's topsoil erodes and a centimetre of new soil takes possibly a millennium to form. Vegetation and soil ecosystems purify water. For example, wetlands are increasingly being used to treat sewage effluent, and vegetated water catchments supply much cleaner water to water storages than cleared catchments. The quality of our drinking water is directly affected by the quality of our catchment areas. The scale of most of these services is so large that it would be impossible to find technological substitutes. In addition, many of our aesthetic, educational and spiritual needs are provided for by the natural environment. Our wellbeing and future are inextricably linked with that of our ecosystems. Consequently, we need to protect ecosystems and their natural services for future generations. Information sourced from:
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