Physical geography Flashcards
What defines a species?
A group of individuals that has the potential to produce fertile offspring and cannot reproduce with other groups
Genetic diversity?
Variation in individuals genetics between and within populations
Higher potential to survive long term as they have higher resilience
Ecosystem/ecological diversity?
the variety of ecosystems within the biosphere
Variety in flora
Species diversity?
the variety of species in a given area.
Why is biodiversity so important?
Different reasons. Insures carbon storage
as well as water resource and pollination for food production can be provided
Tropical biomes
Tropical forests = warm and humid all year around, equal temperature and a lot of energy and water. Nutrients cannot enter deeply in soil. Soil fertility stays in top layer. Big animals are high up in the trees competing for sunlight for photosynthesis.
Hot deserts = Extremely dry climate. No vegetation usually occurs.
Savannah = Warmer climate, close to tropical rainforest but has dry season. Growing of trees is therefore limited by amount of water falling. One large transition zone from rainforest to desert
Temperate biomes
Mediterranean, evergreen, grassland
Cold biomes - higher latitudes
Tundra = competition for nutrients. Many bulbs - a way to survive as it grows underground. Short growing season above ground. Short succession stages mostly mosses and no trees can grow
Taiga = cool climate and little precipitation.
Podzolic soils.
Coniferous forests
Epiphytes
Plants that grow on another plant.
Example is pineapple. Often in rainforest. Cannot capture roots in the soil themselves.
Coral reefs biome
Covering small areas but accounting for over 1/4 of the oceans total species biodiversity.
Can help us reveal the past climatic history.
Estuaries
Transition zones where the freshwater of the river meets the salt water of the ocean (examples include: mud flats and mangrove forests)
Succession
The sequential change in species over time following a disturbance event.
Disturbance: forest fire or volcanic eruption
Example: Taiga
Final succession stage is coniferous trees as its too cold for further development of forest
Primary succession
Starts in an area that has a complete lack of life (perhaps because of a volcano erupting)
Lacks competition
Secondary succession
Takes place after less dramatic disturbances (forest fires for instance, deforestation or construction activities). Soil existed before and can therefore progress faster than soil in primary succession
Habitat corridors
Can help to deal with fragmentation in nature. To connect patches of an ecosystem. To help species migrate. Examples could be tunnels under big highways to join two habits together.
Island biogeography theory
Islands tend to be less biodiverse because of water or other features blocking access to mainland for species to migrate.
However niches develop for special species that become endemic (only existing at a certain spot)
Larger islands = greater richness in species than smaller islands as larger islands probably have more resources and different habits.
Longer distance to mainland means less richness as more difficult for species to migrate
Ecosystem services
The direct and indirect contribution of ecosystems to human-well being
4 categorises of Ecosystem services
Provisioning, cultural, regulating and supporting
Regulating ecosystem services
Indirect services of ecosystems. The benefits of having a regulating water system, climate system and erosion system
Example: presence of trees allows the impact of heavy rainfall on the soil to be moderated by the barrier provided by leaves or branches while allowing a longer period for soil water replenishment.
Cultural ecosystem services
The non-material benefits. The aesthetic, knowledge, social and spiritual (ethical too).
Difficult to put a price on.
What we leave for the future (the lost biodiversity).
Supporting ecosystem services
Indirect services.
The soil formation, photosynthesis, water cycle
Provisioning
The direct supply from ecosystems. The products. The food, the fuel, fibre and pharmaceuticals.
What essential functions does soil perform?
Reservoir for water (aquafiers etc), medium for plant growth and food, filters the air and the water, recycles dead plants/animals, storing huge amounts of carbon
Main components of soil
45% mineral. 25 % air. 25% water. 5% organic
Mineral part of soil
Formed by weathering of parent material.
Primary minerals = changed little since formation
secondary minerals = formed from breakdown and chemical weathering of less resistant primary minerals
Soil litter
remainder of decomposed animal and plant waste
Soil humus
A dark and organic material that forms in soil when plant and animal matter decays
Soil biomass
living organisms and plant roots
Mineralisation
The process where the breakdown of organic matter by microorganisms leads to nutrients being released such as nitrogen, carbon and phosphorus
Water in soil
Important as it is required for parent material weathering.
Saturated soil
When all the soil is saturated the pores are filled with water
Soil air
The air within the soil occupies the pore spaces within the soil (if it is not saturated with water that is)
Soil profile
Vertical section through the soil from ground surface down to the parent material.
Soil horizons
The layers within the soil profile.
O, A, E, B, C, R
O horizon
Basically the surface layer (soil humus). Consisting of organic matter (decay of animals and plants). Not always present.
A layer
The topsoil.
Contains rich organic material with minerals. High concentration of organic matter and microorganism.
E horizon
Elevation layer (may be missing in some soils) Mineral horizon. Lighter in color
B horizon
Also mineral horizon but enriched in iron
Soil of acculumation.
C horizon
Loose material. Much of original material and fragments. often light in color.
R horizon
Bedrock. Form parent material.
Pedogenesis
Process of soil formation. The soil horizons develop after number of processes.
Processes like weathering, winds, rain etc.
A rock splits and expands leading to smaller particles entering the soil with new minerals.
Addition of pedogenesis
Comes from parent material. Can also be material gathered by wind or energy from the sun
Losses of pedogenesis
Removals from soil because of erosion or filtering
Mixing of pedogenesis
Mixing of organic and inorganic components is carried out by soil animals and plant roots or by freezing of water and shrinking and swelling. humans = ploughing
Factors affecting soil formation - Climate
Perhaps the most influential factor. Determines the moisture level and temperature and therefore amount of precipitation (affecting weathering).
Hot and wet climate soil are very different to soil in cold and dry climates.
Factors affecting soil formation - topography
Altitude = can quickly change climatic conditions (usually drier and colder)
Higher slopes = allows for more erosion.
lower temp = less biological activity and less decomposition of organic matter
Factors affecting soil formation - organisms
Earthworms or other small animals mix and freshen the soil. Found to increase the infiltration rate
Could be animals, plants rooting or even humans ploughing that change biological factors such as moisture
Factors affecting soil formation - time
Time continually forms the parent material under the influence of the other factors.
Sedimentation and depositing takes time.
Impact of human activities on soil - erosion
further accelerated by human activities. Farming such as removal of vegetation and heavy machinery could affect. In turn this impacts our food supply chains.
Impact of human activities on soil - acidification
enhanced by use of fossil fuels resulting in acid rain and overuse of nitrogen fertilizers.
The more hydrogen ions the more acid the soil is.
Impact of human activities on soil - pesticides
Human use to protect crops. Have a broad spectrum activity.
Salinization and soil
Salt increase leading to less fertility.
Soil compaction
Caused by heavy machinery or trampling of livestock especially in wet soil conditions. Leads to reduced porosity of the soil and therefore increases risk of erosion as less water can infiltrate soils pores (less saturation can take place)
Climatic variables affecting plants - light
Green leaves capture light via photons (green pigments -chlorophylls) which leads to carbon being absorbed and converted into glucose which is needed for the growth
Climatic variables affecting plants - water
Supply of water needed for growth. Drought can be dealt with by shedding the green leaves for instance.
The turgor needs water to keep leaves up
Climatic variables affecting plants - temperature
Reactions involved in photosynthesis require warmth. Best between 10 and 30 degrees.
Climatic variables affecting plants - carbon dioxide concentration
Increase in co2 leads to increase in photosynthesis.
The northern tree line
Geographical boundary where trees grow more slow
Formation of ocean basins
When two plates spread apart and new crust is formed at the mid-ocean ridge as a result the ocean basin will grow larger and larger.
Continental shelf
Area of seabed where most of the coarse-grained sediment derived from erosion is deposited. Shallow water and closest to land. First transition into deep ocean
Continental slopes
Similar to mountain ranges on continents but below ocean surface. From continent into ocean crust.
Physical properties of ocean - salinity
Chemicals that make up salt in seawater were originally derived from chemical weathering of rocks on land. From river into ocean.
Higher salinity in oceans that experience drier climate as more evaporation occurs there.
Physical properties of ocean - temperature structure
Oceans are important in controlling climate on earth. Surface water gain temperature from sun radiation and heat is lost by evaporation. Stores energy from the sun
Ocean circulation - surface currents
Driven by winds. Trade winds blow out of the south east (southern hem) and out of north east (northern hem).
Ocean circulation - deep currents
Driven by density variations (driven by salinity and temperature) = thermohaline cirulation. Dense water sinks
Life in the ocean - photosynthesis
Plants that photosynthesise. Example is phytoplankton.
Important nutrients to the ocean
Nitrate and phosphate = fertilizers of the sea
usually estuaries are places with high productivity. Could lead to eutrophication where unnaturally high productivity occurs.
Ocean waves
a factor for shaping the coats and driving nearshore sediment transport. Generated by wind. Stronger wind= stronger wave.
Wave length
Distance between successive crests (one cycle)
Wave period
The time is takes for the wave to travel a distance equal to its wavelength
Wave height
Difference in elevation between the crest and the trough (amplitude which depend on speed of wind and the distance the wave is travelling)
Wave shoaling
The process whereby the waves change in height as they travel into shallower water (as it is decreasing in speed and length but the height increases)
Surf zone of waves
Where waves are suddenly seen to ‘‘pick up’’ and becomes steeper as a result of breaking the wave shoaling
Wave refraction
The waves don’t flow straight but in a slight angle when dumping sand on the land. That is how the particles will be distributed on the coast. Gives a smooth shoreline
Types of coastal processes: storm surge
Significantly elevated water level near the shore (examples: hurricanes). Causes depend on: low pressure, onshore wind, coastal topography
Types of coastal processes: tides
caused by gravitational attraction of the earth-moon system and the earth-sun system.
The difference between high and low tide = tidal range (pressure gradients)
When sun and moon are facing same direction they pull water towards them
When not facing same direction the water is not pulled outwards.
Moon causes gravitational force on earth. The part of earth that is directed towards the moon will be pulled outwards while rotating simultaneously.
High tide = the pulling towards moon
Spring tides
Extra powerful tides when the earth, moon and sun are all aligned.
Twice a moon when you have full moon or new moon.
Types of coastal processes: tsunami
Cause can by: earthquake, large landslide into ocean or impulse generated by a meteorite. Long wavelength and small height therefore faster first but becoming shorter in wavelength closer to the shore and increase in height but decrease in speed.
Wave dominated coasts: barriers
Barrier islands, lagoons, estuary. Often made up of sand.
Transgressive barriers
Barriers that move towards land under influence of rising sea level or negative sediment budget. For instance tidal deltas
Regressive barriers
Strandplains that develop under influence of falling sea level or positive sediment budget.