The Critical Zone Flashcards
What is the biosphere?
- The biologically inhabited part of the earth
- Deep oceans to atmosphere
- Interacts with lithosphere (geology), hydrosphere and atmosphere
What is biogeography?
Branch of geography which explores patters - why are organisms where they are?
What is historical biogeography?
- Looks at reconstructing the origin, dispersal and extinction of species or taxonomic groups
What is ecological biogeography?
- Looks at present distributions and geographic variations in diversity, environmental constraints on species distribution and how biotic and abiotic interactions influence species distribution
What happens in the critical zone?
- All activities and resources that sustain human life
- Food and fuel production
- Biological gene pool
- Carbon storage
- Clean water and soil
What is species distribution a result of?
A result of multiple biotic and abiotic drivers
What are the biotic factors which drive species distribution?
- Influence of ecosystem engineers (humans, beavers)
- Interacting among species - competition
- Individual response of species - extinction
What are the abiotic factors which drive species distribution?
- Geographic template
- Temporal dynamics of the geographic template - tectonics, sea level change, climate change
- processes occurring on geological timescales results in temporal patterns of species distribution
What are the biological drivers of biotic factors?
- Some biota may respond to environmental variation - adaptation, evolution, dispersal or extinction
- Some species act as ecosystem engineers and alter the physical environment
What are the four main processes regulating biogeographical patterns and species distribution?
1) Abiotic processes - physical environment that is external to organism
2) Physiological processes - how a species adapts and evolves
3) Biotic interactions - symbiosis, mutualism and parasitism
4) Historic events - how did a species get there - invasive
What is the natural world described as?
- A series of biogeographic units
- Allows a collective description of processes and structures
What are the different scales of the natural world?
- Biome - global/continental spatial scale
- Ecosystem - a community of organisms and its environment in one unit
What is a biome?
- Biological meta communities
- Similar but unconnected regions
- Two master variables - temp and precipitation
- Collections of areas with similar a biotic factors that produce similar ecological communities
What are the biome characteristics of a tropical rainforest?
- Dominated by broad-leaved evergreen species
- High biodiversity
- Hot and wet
- Poor, thin soil
- evolution was not disrupted by glaciation
- High productivity - range of resources
What are the characteristics of a savannah grassland biome?
- Grasslands with low density trees and shrubs
- Support Hugh number of herbivores, large grazing mammals
- Warm/hot climate
- Rainfall - 6/8 months
- Maintained through droughts and fires
- Shallow soil
What are the characteristics of the desert biome?
- Hot and dry
- Covers 1/5 of earths surface
- Specialised flora and fauna
- Less than 50cm/year of rain
- Soils are nutrient rich
- Low plants, small thick leaves
What are the characteristics of a temperate deciduous forest biome?
- Broad leaved deciduous trees
- Less dense, shorter forests
- Few dominant species
- High rainfall
- Rich soils
What are the characteristics of a temperate grassland biome?
- Mostly grasses
- Steppes and praises
- Some trees
- Grazed by large mammals
- Deep nutrient rich soil
What are the characteristics of a tundra biome?
- Low biotic diversity
- Artic shrubs mosses, grasses and lichen
- Alpine dwarf trees, shrubs and grasses
- simple vegetation structure
- Low temp and no rain
- Poor nutrient soils
Define ecosystem structure
Biotic and abiotic components or attributes within an ecosystem
What are the two most important functions in an ecosystem?
Energy and nutrient cycling
What is energy and nutrient cycling controlled by?
- Producers
- Consumers
- Decomposers
- Water cycle
What is primary production?
- Generation of biological material by plants – photosynthesis
- Key process -conversion of inorganic carbon dioxide to organic carbon
- Autotrophs – self feeders
- Not often at equilibrium
What cause an ecosystem to change?
- Changes in structure
- Relative species abundances
- Species immigration/emigration (local extinction)
- Feedback to changing abiotic conditions such as soil fertility, microclimate
- Does not mean ecosystem is not stable
What is succession?
- Disturbances destroy existing habitats and create new ones
- These are then colonised by species, creating new ecosystems
- Colonisation of bare ground is called primary succession
- Secondary succession occurs when existing vegetation is removed
