chapt 32-ecosystems

What is a biome, and what factors affect the distribution of biomes on Earth?

large geographic area characterized by climate, vegetation, and animal life

• vegetation reasonably homogenous over large terrestrial area

• elevation

• temperature

• latitude

Given that tropical rainforests contain such a diversity of species, why are many kinds of tropical soils unsuitable for agriculture?

• Low nutrient content- lack nutrients like nitrogen, phosphorous, and potassium [gets washed away]

• rapid decomposition prevents accumulation of rich humus layer

• soil prone to erosion

• Acidity

• High porosity, water drains quickly

Which factors favor grasslands over wooded ecosystems? What role does fire play in grasslands?

• Climate: typically found in regions with moderate rainfall, water availability is insufficient to support dense forests

• Soil nutrient rich favor grasses

• Grazing by animals prevent establishment of woody plants

• Fires help maintain grasslands to recycle material

Which best characterizes a desert: high temperature or low precipitation? How have plants adapted to desert living?

• Low precipitation

• Water storage in plants-thick stems

• Reduced water loss-minimal leaves, waxy coatings

• Deep roots: extensive root system to get water from deeper in the ground

• Desert plants use Crassulacean Acid Metabolism (CAM) → specialized photosynthetic pathway that allows them to open their stomata at night to conserve water

How does the appearance of the temperate deciduous forest biome change from one season to the next? What accounts for these changes?

SPRING: forest floor becomes lush with vegetation. This growth is fueled by the availability of water and nutrients, as well as the longer days

SUMMER: forest is at its peak, with dense green foliage providing a canopy that shades the forest floor.

FALL: Leaves change color to vibrant shades of red, orange, and yellow as chlorophyll breaks down and other pigments become visible. preparation for winter, as trees conserve energy by shedding leaves to reduce water loss during the colder months

WINTER: forest appears bare and stark, with trees stripped of their leaves. Many plants and animals enter a dormant state

What is the general global pattern for biodiversity, and what factors might explain it?

• latitudinal diversity gradient

• Highest biodiversity in tropics, decrease toward poles

  • Tropical regions have relatively stable climates year-round, which supports a wide variety of species

  • Higher levels of sunlight and warmth in the tropics promote primary productivity

  • Tropical regions have been climatically stable for longer period

  • numerous niches for different species

Traits that affect where in the world a plant can live?

• xero/mesophyte stoma

• Nutrient availability

• Pollination mode

• Root absorption capacity

• Photosynthetic capacity

• Competitive capacity/shade tolerance

• Secondary metabolite

• Physical structures

• Resistance to wind/hardiness/wood strength

• Reaction wood (tension and compression)