A2 Geog- Biodiversity

Ecosystem.

A biological community of interacting organisms and their physical environment.

Alien/ invasive species.

Accidental -Ships- mussels on the sides of ships or in ballast water. -Air transport. -Galapagos rats eating tortoise eggs. Intentional -Rainbow trout and pheasant in the UK for game and hunting. -Hedgehogs in the Outer Hebrides to control slugs- now out of control and affecting energy flows. -Plant species for decoration purposes- Rhododendron in country estates from the Indian subcontinent).

How altitude affects biodiversity.

As altitude increases, there are fewer species; they grow less tall; and they provide a less dense cover. As altitude increases: -No. of species declines -Height of plants declines. -Density of plants declines. -Growth rate of plants declines. -Length of growing season declines. -Biomass declines. UV light on mountains reduces no. of species found there. High altitudes have a less dense atmosphere so only few species are able to sustain life with lack of oxygen.

Genetic diversity.

Classifies biodiversity according to the no. of genes found within a particular species. This determines the resistance to pests and diseases.

Continentality.

Distance from the sea.

Two processes vital to ecosystem functioning.

Energy flows -Primary producers at trophic level 1 convert light energy to chemical energy via photosynthesis. -A food chain exists between the different trophic levels, resulting in energy flowing through the food web over time. -Some energy is lost through respiration and decay. Nutrient cycling -Circulation of chemical elements from the environment to organisms and back again. -Nutrients stored in 3 parts of the ecosystem; in the soil, in the living biomass and in the surface litter.

Factors affecting biome distribution.

Global -Latitude= temperature, sunlight hours, sunlight intensity and air pressure. Local -Altitude -Aspect/slope angle -Soil type/depth -Drainage -Continentality -Geographical isolation. Human factors -Deforestation -Conservation practices -Agricultural practices -Human interference -Global warming

Net Primary Productivity

How much CO2 vegetation takes in during photosynthesis minus how much CO2 the plants release during respiration.

How continentality affects biodiversity.

Land is quick to heat and quick to cool. Water is slow to heat and slow to cool. Continental places, far inland, have greater temperature extremes. Coastal regions have less extremes of temperature.

How latitude affects biodiversity.

Latitude influences intensity of the sun in a region. The angle and duration of the suns energy determine surface temperature so that higher latitudes receive less heat but lower latitudes, closer to the equator receive more. Latitudinal diversity gradient- increase in species richness or biodiversity that occurs from the poles to the tropics. Different circulation cells exist at particular latitudes which affect climate and therefore biodiversity. -Hadley cell-equator->30-40degrees N&S. Trade winds blow towards equator, ascend near equator as broken line of thunderstorms (forms ITCZ). From top of storms, air flows to higher latitudes where it sinks to produce high pressure regions over the world's hot deserts. -Ferrel cell-middle cells. Air converges at low altitudes to ascend along the boundaries between cool polar air and warm subtropical air 60-70degrees N&S. Produces unsettled weather-opposite direction to other cells. -Polar cell-smallest & weakest cells- 60-70degrees N&S-> poles. Air sinks over highest latitudes and flows out towards lower latitudes at the surface.

How development relates to level of threat faced by ecosystems.

Less developed countries -Perception= need to use ecosystems as a direct source of income. -Action= deforestation, conversion to farmland, overfishing. -Impact= degradation of biodiversity. More developed countries -(Education to alter perception)= need to conserve ecosystems and use sustainably. -(Provision of alternative income sources and management methods)= management of ecosystems and sustainable yields. -Impact= positive impact of biodiversity.

Factors affecting NPP

Moisture levels- key component for chemical reactions. Temperature- speeds up chemical reactions. Nutrient availability- from soils etc. Light- for photosynthesis.

How geographical isolation affects biodiversity.

Movement of tectonic plates and other slow geologic events cause geographic areas to move apart. -Pops of organisms become isolated. -Separated pop of species evolve in different ways as they adapt to different environments. Darwin's finches -Finches descended from common ancestor stranded on the Galapagos islands, isolated from South America. -They evolved to fill many ecological niches on different islands- evolution found in their beak shape. -Beaks different sizes/shapes dependent on the food the species had specialised in eating. -Finches with best adapted beaks for each kind of food succeeded and gradually became new species.

Ecosystem diversity.

No. of ecosystems in a given area. Controlled by physical conditions inc. climate, geology, relief and soils. Ability of humans to modify and eliminate ecosystems is a threat to ecosystem diversity.

Ecosystem services

Provisioning services/ goods- products obtained from ecosystems inc food, fuel, medicines etc. Regulating/ supporting services- benefits obtained from the regulation of ecosystem processes, e.g air quality, climate, water etc. Cultural services- non-material benefits that people obtain from ecosystems e.g knowledge, recreation, ecotourism, cultural heritage, spiritual and religious values.

Geographical isolation.

Separation of a population of organisms from the rest of its species due to a physical barrier such as mountains or an ocean.

How slope angle/soils/aspect affect biodiversity.

Slope angle influences soil depth, pH and drainage. Steeper slopes usually have thinner soils, are less water-logged and less acidic than gentler slopes. Aspect affects sunlight, temperatures and moisture. South-facing slopes in the northern hemisphere more favourable than those facing north because they are brighter, warmer and drier. Plant growth is affected by soil texture, structure, acidity, organic content, depth, water and oxygen content, and nutrients.

Endemic species.

Species unique to an area.

How do deforestation and overharvesting cause disruption to nutrient cycling and energy flows?

They disrupt the balance of these processes which alters the levels of nutrients present in the ecosystem.

Species diversity.

Variety of plants and animals present in an ecosystem. Strong species diversity makes an ecosystem more resilient to climate change.

Inter-Tropical Convergence Zone

Where 2 tropical land masses converge- found between 2 Hadley cells. Position of the ITCZ changes throughout the year. Savannah ecosystems often affected by these changing rainfall patterns. -Lower biodiversity as conditions are often too dry to support certain species. ITCZ moving in the eastern hemisphere limits biodiversity as there are 2 extremes in climate. Where there is little shift in the ITCZ (around Brazil) there is consistent rainfall all year- enough to support a rainforest.