MODULE 021131: ECOLOGY Learning Objectives: Lecture 1? Ecology covers a hierarchy of levels of organisation, from individual to biosphere? There are distinctive (emergent) properties of ecological systems at each of these scales that can only be understood by studying them at the appropriate scale: a strictly reductionist approach is invalid? If an ecological problem is to be successfully resolved, it must be studied at all appropriate scales
Ecology as a hierarchy Molecule cell Organism Population Community Ecosystem Landscape, biome, biosphere
At the level of the individual organism: Phenomena include animal behaviour, ecophysiology Applications are in species conservation, land management
Large blue butterfly Maculinea arion: unique life-history is the key to its conservation
Spring gentian Gentiana verna: found only in a few places in Britain, and sensitive both to soil conditions and grazing
Habitat of G. verna in Upper Teesdale, County Durham. The fence controls grazing and allows abundant flowering. The reservoir in the background flooded over half the habitat of this rare species
The lichen Hypogymnia physodes: lichens are highly sensitive to air pollution and are rare in urban areas. Their sensitivity can be used as an index of pollution intensity
Derelict coalmine waste in the central Lancashire coalfield: grass growth is poor and restricted to gulleys where water collects Derelict land encourages other lowvalue uses of land and depresses the local economy
Plants cannot grow on the waste, due to extreme deficiency of mineral nutrients such as phosphate Sown grass seed soon dies of drought as a result of inadequate growth of their root systems
Adding ground limestone (CaCO 3 ; to raise the soil ph) and fertilisers allows grass growth on otherwise barren sites No limestone Limestone added The individual plots received different combinations of N, P and K fertilisers
At the population level Phenomena: population dynamics, extinction, competition, predation Applications: invasions, pest control, biological control, conservation management
Himalayan balsam Impatiens glandulifera an introduced species that has escaped from gardens and now dominates in waterside habitats produces huge numbers of seeds and can swamp all competitor species
Touch-me-not balsam Impatiens noli-me-tangere is a closely related native species that is now very rare in Britain. Why is one species an invasive weed and the other rare and threatened?
Invasive species can have large economic consequences Patterson s curse Echium plantagineum can take over entire fields in Western Australia
Australian vegetation is especially prone to invasions: almost all the species in this scene are introduced from either South Africa or the Mediterranean
Species that are well controlled by natural enemies in their native range, such as this prickly pear Opuntia in South America, can become damaging weeds in another country: here Australia. Prickly pear was eventually controlled by introducing a moth Cactoblastis cactorum whose caterpillars ate it
Community level: Phenomena: biodiversity, succession Applications: habitat management, biodiversity conservation
What is the appropriate way to manage biodiverse habitats such as chalk grassland?
Species-rich grassland is maintained by grazing when grazing is removed, coarse grasses dominate
Tropical wet forests are the most diverse habitats we know: why are they able to support so many species?
Ecosystem level: Phenomena: nutrient and material cycles, stability, ecosystem services Applications: pollutant transport, eutrophication, acid rain, sustainable agriculture
A polluted ditch threatens an important wildlife habitat: Askham Bog, near York
Higher levels: landscape, biome, biosphere Phenomena: dispersal, Applications: global change, sustainability
Soil erosion can have catastrophic consequences for the environment: a dust-storm in Mexico
Long-distance transport of eroded soil connects distant ecosystems
Reductionism can one explain higher levels or organisation by understanding the lower levels? does the study of the natural world ultimately reduce to physics? emergent properties