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river estuaries there are often areas of salt marsh that are flooded with every tide. Swamps and swamp forests are regions where the soil is saturated with water, and usually flooded. Many exist around the edges of trop- ical lakes. Swamp forests are dominated by special types of trees that grow well in waterlogged soil. Mangrove forests fringe the coasts of many tropical countries. They are tidal, so the trees that live there have to be able to grow with their roots in salt water. There are several different families of man- groves. Mangrove forests protect shorelines and support an immense variety of wildlife. Sometimes dead plant material builds up in waterlogged areas quicker than it can decay. The resulting layer of slowly rotting plant material is known as peat. Peat bogs are wetlands where the peat has A biome is a very large ecological area, with plants and animals that are adapted to the environmental conditions there. Biomes are usually defined by physical characteristics—such as climate, geology, or vegetation—rather than by the animals that live there. For example, deserts, rainforests, and grasslands are all examples of biomes. Plants and animals within the biome have all evolved special adaptations that make it possible for them to live in that area. A biome is not quite the same as an ecosystem, although they function in a similar way. An ecosystem is formed by the interaction of living organ- isms within their environment. Many different ecosystems can be found within a single biome. Components of most ecosystems include water, air, sunlight, soil, plants, microorganisms, insects, and animals. Ecosystems exist on land and in water, with sizes ranging from a small puddle to an enormous swath of desert. Biome versus Ecosystem

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Wetlands