2. urban systems Flashcards
what is the anthropocene
age where human behaviour influences earth systems.
how are cities classified
in general classified by size, growth (ie growing or static) and growth rate.
there are more effects on the ecology of cicties as in ‘natural terresterial systems” ie longutidala nd lattiudinal effects.
economic cotext a
what is a mega city
cites combined through infrastructure
why are cities hostile for nature
- fragmentation leads to the area and edge effects and isolation causing small populations
- heat island effects, hotter due to less shade cover from trees, albedo surfaces, reduced transpiration,
- invasive species easier to adapt to urban environment
- pollution (noise, light, water, air)
- disturbance (lack of fire, overuse
- more nurtients which native species arent used to.
what are some challenges of classifying cities
ecological gradients, where do cities end and how do they change from urban to rural, do they change in predictable ways?
no replicates, each city is unique
why do urban envrionments chnage plant growth
some positive effects of pollution, exposed to reduced nox (ozone depletion) and higher temps = more biomass
why do urban environments change bee memory
exposure to pollution = harder to learn and remember
differenced between egde, interior and small remnant pacthes affecting bird communities
higher insects in small patches compared to interiorpatches, reason, more generalist in small and more specialised insectivours in interior patches
what do higher insect populations in urban renmant pacthes mean ?
higher herbivory, delcines in urban forests. an example fo loss of higher trophic levels/ top predators = decline in primary producers. disruption of ecological proccesses.
= dieback
goal of restoration
recreating a function syste, that are self sustaining. to build vegetation and species will follow.
look at the proccesses; pollination, seed dispersal, predation etc
example ant and seed dispersal for reveg spaces.
no real change in species richness between reference and reveg compared to remnant however
sig difference in seed removal.
therefore while the numebrs arent coming back you only need the specialists to replace generalists (key functional groups)
novel ecosystems, urban assmebledges and winners and losers
what is the reference point and why do we want to return to native and natural. if the functional groups are there and the habitat is self sustaining then that should be celebrated even if they arent native or as diverse.
why are there winners and losers?
intensive selective pressure
