Environments Study Guide Natural events occur in nature and include fire, floods, storms, drought and erosion. Natural events can cause rapid or slow changes to the environments. Rapid changes Fire Flood Storms Earthquake Landslide Slow changes Drought Erosion Natural events can have both positive and negative effects on the environment. Fire- natural and caused by humans Positive Make room for new plant growth Release nutrients Hot temperatures open some seeds Negative Destroy living things & habitats Smoke causes pollution Floods- natural Positive Flood waters deliver nutrient-rich sediments to land Negative Removes soil that plants need to grow May make water unclean or spread disease Destroy habitats and living things Storms- natural Positive Precipitation from storms provides water that is needed by organisms in environments Lightning helps plants by releasing nutrients in soil Lightning also produces a gas, called ozone that helps protect environments from the sun. Erosion- natural and caused by humans Positive Soil is delivered to other areas where it can be used by plants living there. Negative Destroy habitats, causing floods, and hurting or killing organisms Lightning from storms can start wildfires Strong winds from storms knock down trees and can even destroy forests. Negative Remove nutrient-rich soil needed for plant growth Wind erosion can make dust storms that block out sunlight. Droughts- natural Positive Negative Plants die Animals that eat plants may starve. More erosion takes place, dust storms form Rivers, lakes, and wetlands may dry up. Habitats may be destroyed Animals may leave to find water elsewhere. More fires may take place in areas experiencing a drought Pollution- natural and caused by humans Positive Dams- caused by humans Positive Storing water Controlling floods Make electricity Forrest Clearing- caused by humans Positive Negative Harmful gases in the air may hurt organisms when they breathe of the gases, such as carbon dioxide, cause the greenhouse effect which is the rise in Earth's temperature Rising temperatures on Earth could change weather patterns, cause droughts, melt glaciers, and cause rising sea levels. Water pollution harms organisms that live in or use the water. It makes organisms sick and can even kill them. Plants may not be able to grow in polluted land, and other organisms may become sick from the pollution Negative May cause rivers to become dry. Stop nutrient-rich sediments from flowing downstream. Plants and other organisms that live in the water are not able stay healthy without the sediments. Break habitats into smaller pieces and separate organisms into different areas Negative Causes habitat loss Crop plants take the place of native plants Can lead to erosion Animals lose resources