Climate and Life on Earth Flashcards
What determines the distribution and diversity of major terrestrial biomes
Variations in temperature and rainfall on a global scale
What is primary productivity
The rate at which biomass is produced via photosynthesis, representing energy entering ecosystems
What factors shape large-scale patterns of primary productivity
Insolation, climate, and nutrient availability
What role does local variation play within biomes
Topography, geology, and soil influence ecological communities and productivity on smaller spatial scales
How can ecological communities change over time
Through ecological succession and climate change
What influences large-scale biogeographic patterns
Latitude and elevation
What defines a biome
A zone dominated by plants with characteristic shapes, forms and physiological traits
What two factors explain the distribution of terrestrial biomes in Whittaker’s model
Mean annual temperature and annual precipitation
What is an example of convergent evolution in biomes
The Mediterranean biome, where unrelated species evolve similar adaptations to similar climates
How do meso-scale changes affect habitat
Elevation and aspect (e.g. Mt. Kilimanjaro) create steep abiotic gradients, resulting in different habitats in a small area
How is Gross Primary Productivity (GPP)
The total energy fixed by autotrophs (plants, algae) through photosynthesis
What is Net Primary Productivity (NPP)
GPP minus autotrophic respiration; the energy available to consumers and decomposers
What is secondary productivity
The biomass produced by heterotrophs, using the energy from NPP
In what units can primary productivity be measured in
Energy/unit area (e.g. kJ/m²/year)
Mass of carbon or dry organic matter
Do different biomes have different NPPs
Yes, annual NPP varies greatly between biomes due to differences in climate and resources
What are the four main factors that limit NPP in terrestrial systems
- Solar radiation
- Water availability
- Temperature
- Nutrient availability
How does solar radiation affect NPP
More light = more potential photosynthesis, but efficiency varies and is often limited by other factors, especially water
How does precipitation influence NPP
More water supports more productivity, especially in otherwise high-insolation environments
How does temperature affect NPP
Higher temperature:
Increases photosynthesis
Accelerates evaporation
Speeds up decomposition → more nutrient release
When is productivity possible
Only when plants can photosynthesise - often seasonal, especially outside the tropics
Which nutrients most commonly limit NPP and why
Phosphorus and Nitrogen
They are required in large amounts, but not always available in usable forms or adequate quantities in soils
