Communities, Biomes, Ecosystems(Populations), & Biodiversity

Weather vs. Climate Weather is the day-to-day condition of Earth’s atmosphere. Climate, on the other hand, refers to average conditions over long periods. A region’s climate is defined by year-after-year patterns of temperature & precipitation. What are the factors that affect climate? 1)Solar energy-arrives as sunlight & strikes Earth’s surface. Some is reflected back into space, and some is absorbed and converted into heat.

Factors that affect climate continued Some of that heat, in turn, radiates back into space, & some is trapped in the biosphere. The balance between heat that stays in the biosphere and heat lost to space determines Earth’s average temperature. 2)Latitude-Earth’s climate zones are produced by unequal distribution of the sun’s heat on Earth’s surface. Polar regions receive less solar energy per unit area, and so less heat, than tropical regions do. The tilt of Earth’s axis causes the distribution of sunlight to change over the course of the year

Factors continued 3)Transport of heat by winds & ocean currents-Earth has winds because warm air is less dense & rises, and cool air is more dense & sinks. For this reason, air that is heated by a warm area of Earth’s surface-such as air near the equator, rises. At the same time, in cooler regions, near the poles, chilled air sinks toward Earth’s surface, pushing air at the surface outward. This air warms as it travels over the surface. And as the air warms, it rises. Similar patterns of heating & cooling occur in the oceans.

Primary Succession Primary Succession It occurs on newly exposed surfaces.

Secondary Succession Secondary Succession occurs in distributed areas where remnants of previous ecosystems-soil & even plants-remain. It often follows a wildfire, hurricane, or other natural disturbance.

Major Biomes Biomes are described in terms of abiotic factors like climate and soil type, and biotic factors like plant and animal life. Major Land Biomes 1)Tundra 6)Tropical Rainforest 2)Boreal Forest 7)Temperate Grassland 3)Temperate Forest 8)Tropical Savanna 4)Temperate Woodland & Shrubland 9)Desert 5)Tropical Seasonal Forest

Aquatic Ecosystems Freshwater Ecosystems The major freshwater ecosystems include ponds, lakes, streams, rivers, & wetlands. Plants & animals in these ecosystems are adapted to the low salt content and are unable to survive in areas of high salt concentration.

Rivers & Streams The water in rivers & streams flows in one direction, beginning at a source called a headwater& traveling to the mouth, where the flowing water empties into a larger body of water. Rivers & streams also might start from underground springs or from snowmelt.

Lakes & Ponds An inland body of standing water is called a lake or a pond. It can be as small as a few square meters or as large as thousands of square meters. Nutrient poor lakes, often are found high in the mountains. Few plant and animal species are present as a result of small amounts of organic matter & nutrients. Nutrient rich lakes are usually found at lower altitudes. Many plants & animal species are present as a result of organic matter & plentiful nutrients.

Transitional Aquatic Ecosystems Wetlands-Areas of land such as marshes, swamps, and bogs that are saturated with water & that support aquatic plants. Wetlands have high levels of species diversity-amphibians, reptiles, birds, mammals, duckweed, pond lilies, cattails, mangroves,etc. Estuaries-an ecosystem that is formed where freshwater from a river or stream merges with salt water from an ocean. Wide variety of species found there: algae, seaweed, marsh grass, worms, oysters, crabs, mangrove trees, ducks, geese, and marine fish & invertebrates(shrimp)

Historical Overview of Human Population The human population, like populations of other organisms, tends to increase. The rate of that increase has changed dramatically over time. For most of human existence, the population grew slowly because life was harsh. As civilization advanced, life became easier, and the human population began to grow more rapidly. Our population growth rate in the US has now slowed down some, but other countries are growing rapidly. The anticipated human population by the year 2050 is about 9 billion.

Population Limiting Factors Density independent factor- any factor in the environment that does not depend on the number of members in a population per unit area: Ex. Drought, flooding, extreme heat or cold, tornadoes, and hurricanes. Density dependent factor-any factor in the environment that depends on the # of members in a population per unit area; Ex. Predation, disease, parasites, and competition.

Population Growth Rate Emigration-the # of individuals moving away Immigration-the # of individuals moving into a population Exponential growth rate is represented by a J shaped curve Logistic growth rate is represented by an S shaped curve Carrying capacity- the maximum # of individuals in a species that an environment can support for the long term