Transcript Succession
SUCCESSION Change of ecosystems over time • New habitats are created when a volcano forms a new island, a glacier recedes and exposes new rock or a fire burns all vegetation in an area. How does an ecosystem develop? We can study that by watching what happens in an area where there has never been soil Primary succession • Succession that occurs where plants have not grown before is called primary succession. Primary succession following the retreat of a glacier. Soil begins with weathering of rocks and establishment of lichens • First come lichens, which attach to rocks, reproduce – some die. Microscopic fungi and bacteria can move in to decompose the dead lichens. With decomposition, nutrients are added to the soil. The soil can now support small fastgrowing plants. Seeds are deposited by winds or birds. LICHENS Mutualism! Fungi help fasten the lichen to rock , algae do photosynthesis to feed the fungi Pioneer species • The first organisms to live in a new habitat are small, fastgrowing plants, called pioneer species. As the pioneer species reproduce and die, they are decomposed and add more nutrients to the soil. Before long, the deeper richer soil supports the life of more types of plants- this is the start of BIODIVERSITY. More and larger plants provide a home for insects and small animals, which move in, reproduce and die. Their remains makes the soil thicker and richer. Primary succession • The same ground 2 years later, is now covered in grasses and flowering plants, and a host of insects and animals Over time….look what happens! • SUCCESSION!!!! Secondary succession Succession that occur in areas where there has been previous growth. Soil is already present. Secondary succession • A recently cleared patch of ground, left to grow in its wild state After flood or fire Soil is present • Secondary succession happens quickly • The stable community that remains will depend on the climate, and abiotic factors. • A stable desert community looks very different from a temperate forest!...WHY?? Does the picture below represent primary or secondary succession? One last type of succession… pond to meadow HILTON POND- Piedmont NC 1982 The same pond, 10 years later Flagg Pond • Our pond on the BHS campus was once used for canoeing and swimming. It was used to harvest ice in the winter for Ice boxes, before refrigerators were common. It is now getting close to the later stages of succession….. • Go take a walk- look for the signs of succession! One thing is constant in ecosystems… THEY ARE ALWAYS CHANGING!!!