Summary 7: How Ecosystems Change

This topic is about the ¿how ecosystems change? is for example From Farmland to Forest, In first year we have a abandoned farm: a community of crabgrass, insects, and mice invades the field where corn or another crop once grew, Then we have Second and Third Years: tall weeds, such as asters, ragweed, and goldenrod, and tall grasses grow among the crabgrass. The crabgrass can't easily survive in the shade cast by the taller weeds. It begins to die out. Rabbits and seed-eating birds move in. Next Four to Six Years Later: The hot, dry field of tall weeds provides a perfect environment for pine seeds sprout. Pine trees begin to grow and shade the weeds, which begin die out. More birds join the community, as do small mammals like opossums and skunks. Twenty-Five Years Later: A pine forest has replaced the old farm field. Yet the number of new pine seedings drops because they can't grow in the shade. Seeds of decidous trees such as maple, hickory, and oak sprout and take root. Larger animals like racoons and foxes begin to visit,  Finally in One hundred Years Later: The forest is now mostly decidious trees. Thes trees are habitats of many different kinds of birds and small animals, such as squirrels. Deer, racoons, and foxes also live in the forest, that happens when a ecosystem change from Farmland to Forest.