Biomes 1 (18) Flashcards
What is a biome?
A grouping of ecosystems sharing a similar set of plant characteristics under a similar environmental range.
What are the 2 sets of biomes? What are they influenced by?
- Terrestrial: temperature, precipitation, seasonality.
- Marine: water depth, proximity to land, sunlight.
Describe the pattern of distribution of terrestrial biome at the equator and at 30 degree latitude.
Equator: hot + wet with low seasonality = tropical rainforests.
30 degree: warm + dry with moderate seasonality = deserts.
Distribution of biomes with increasing latitude is echoed by increasing what?
Elevation - the biomes change.
Rainforest - temperate deciduous forest - needle leaf forest - tundra - ice and snow.
How does NPP differ across biomes?
NPP differs between terrestrial biomes in a manner consistent with differences in temperature and precipitation.
Lowest NPP: cold + dry
Highest: warm + wet = more photosynthesis
What is evaporation? What is transpiration? What is the net result?
Evaporation is the movement of water directly to the air from the soil and water bodies. It is affected by heat, humidity and wind speed.
Transpiration is the movement of water from root systems, through a plant, and exit into the air as water vapour. Affected by plant type, soil type, weather conditions, and cultivation practises.
Evaporation + transpiration = évapotranspiration. Affected by temperature and precipitation.
Does deforestation reduce or increase évapotranspiration? Why?
Deforestation leads to reduced évapotranspiration.
Plants are good at holding water- removal of vegetation decreases ET and increases groundwater recharge and river runoff.
What is the relationship between NPP and actual évapotranspiration (AET).
NPP is strongly correlated wit AET.
AET combines the effects of temperature and precipitation.
High AET = warm + wet, low AET = cold + dry
High AET = high NPP
What is the relationship between total carbon pool and NPP?
NPP = carbon storage. So, more plants = more carbon storage- less carbon is stored in the atmosphere.
Why is NPP per unit area different between tropical and temperate forests?
The difference in yearly NPP between the two biomes is primarily related to the length of the growing season.
Tropical paces have very consistent growing seasons = more NPP since there is a lot of productivity throughout the year. Tropical forests account for about 1/3 of Earth’s terrestrial NPP.
What plant characteristics define biomes? What are the 3 general plant forms?
Size, shape, foliage structure and chemistry of plants determine many ecosystem prop poetries and the nature of other biota.
Grasses, shrubs, trees.
Explain the different biome patterns in terms of the ecosystem’s stress and disturbance. Which type of plant is associated with each one of the patterns?
- Low stress, low disturbance = competition: ability to acquire resources compared to neighbours.
- trees - Low stress, high disturbance = disturbance: events causing removal of biomass (e.g. herbivores, wind, frost, pathogens, erosion, fire).
- grasses - High stress, low disturbance = stress: any condition that est rictus plant production (e.g. shortage of light, water, nutrients, low temperatures).
- shrubs
Explain how the stress and disturbance create strategies for each form of life and which varies in trade-offs of resource allocation.
Ruderals: allocate resources mainly to seed production, often annuals or short-lived perennials; high growth rate, short-lived leaves, short statures plants.
- grasses
Good competitions: high growth rate, short leaf-life, low seed production, high allocation to leaf construction.
- trees
Stress-tolerators: allocate resources to maintenance and defences; often evergreen; long-lived leaves, low growth rate
- shrubs
What characterizes forests? What are the 2 different types of forests?
Forests have trees which are the dominant or co-dominant plant type.
The 2 different types of forests are based on the longevity of their leaves.
- Deciduous (1 growing season):
- winter-deciduous (temperate regions, low winter T).
- drought-deciduous (subtropical and tropical, leaf shed on dry periods).
- drought avoidance (drop the leaves and dont waste extra energy on maintaining them). - Evergreen (>1 growing seasons):
- broadleaf-evergreen (tropic rainforest, no distinct growing seasons, year-round PS).
- needle-lead evergreen (growing season is short or nutrient availability constraints PS and plant growth).
- drought-tolerance.
Describe temperate seasonal forests.
Dominated by deciduous trees.
- leaves change colour + fall
- thick bark
- shade-tolerant understory
Soil: rich in organic material.
- lots of leaf litter
Challenges: high seasonality (hot summers, cold winters).
