Lewis/Life - Review of Key Concepts

Review of Key Concepts - Chapter 43

Biomes are major types of communities and ecosystems with characteristic species and are located in large geographic areas.
The tropical rain forest is hot and wet, with diverse life. Competition for light leads to vertical stratification. Nutrient cycling is rapid.
Temperate deciduous forests require a growing season of at least 4 months, are vertically stratified, and have less diverse life than tropical rain forests. Tree shapes maximize sun exposure. Decomposers form soil from leaf litter.
Temperate coniferous forests have poor soil and a colder climate. Periodic fires occur in these areas.
The taiga is a very cold northern coniferous forest. Adaptations of conifers include needle shapes, year-round leaf retention, and conical tree shape.
Grasslands are temperate areas with less water than deciduous forests and more water than desert. The more moisture, the taller the grasses.
The tundra has very cold and long winters. A layer of permafrost lies beneath the surface. During the spring and summer, meltwater forms rivers and pools. Lichens are common in the treeless tundra, and animals include caribou, reindeer, lemmings, and snowy owls. Eskers are sandy ridges that break the icy terrain and are remnants of rivers that ran beneath glaciers.
Deserts have less than 8 inches (20 centimeters) of rainfall a year. Desert plants are well adapted for obtaining and storing water, with rapid life cycles and succulent leaves. Animals also minimize water loss with tough integuments, and they are active at night.
Freshwater ecosystems include standing water (lentic systems) and running water (lotic systems). The littoral zone of a lake is the shallow, lit area; the limnetic zone is the lit upper layer; the profundal zone is the dark deeper layer. In the littoral zone, most producers are rooted plants. In the limnetic zone, phytoplankton predominate. Nutrients fall from the upper layers and support life in the profundal zone.
Deep lakes in the temperate zone rely on fall turnover and spring turnover to mix oxygen and nutrients. Young, deep, oligotrophic lakes are clear blue, with few nutrients to support algae. Nutrients gradually accumulate, and algae tints the water green. The lake becomes a productive, or eutrophic, lake. In rivers, organisms are adapted to local current conditions.
Shoreline ecosystems include estuaries, rocky intertidal zones, sandy beaches, and mangrove swamps. Estuaries occur where a river empties into the sea. The richest marine ecosystems are coral reefs of coastal tropical waters.
The region of ocean near the shore is the neritic zone. Open water is the oceanic zone and includes the benthic zone (the bottom), the abyssal zone (the bottom region where light does not reach), and the pelagic zone (open water above the ocean floor). The most productive areas are in the neritic zones where upwelling occurs.
El Nino is a weakening or reversal of Pacific easterly trade winds. Seismic activity beneath the ocean may trigger El Niños. An El Niño alters sea temperature, sea level, and weather patterns in many areas. Many populations migrate or decline in response to blocked upwelling which alters food webs.