Habitat Destruction, Fragmentation, Degradation Flashcards
What are the three ways humans dominate the global ecosystem?
- land surface
- nitrogen cycle
- atmospheric carbon cycle
How have humans dominated land surface?
human land use of resources, mainly agriculture and forestry, have transformed as much as half of the Earth’s ice-free land surface
How have humans dominated the nitrogen cycle?
each year human activities, such as cultivating nitrogen-fixing crops, using nitrogen fertilizers, and burning fossil fuels, release more nitrogen into terrestrial systems than is added by natural processes
How have humans dominated the atmospheric carbon cycle?
by the middle of this century, human use of fossil fuels and cutting down forests will have resulted in a doubling of the level of carbon dioxide in the Earth’s atmosphere
What is major cause of deforestation in rainforest?
- slash and burn
- cattle ranching
What are consequences of deforestation?
- loss of biodiversity
- increase in CO2 leading to increased temperatures
- erosion and increased vulnerability to fire
Where are two places deforestation has severely occured?
Amazon rainforest and Madagascar
What is slash and burn?
trees/vegetation cut down and burned for agriculture
What do nitrogen-fixing bacteria in legume nodules do?
take nitrogen gas (N2) and convert it into a form that most living beings can uptake
Why do we need nitrogen?
amino acids, proteins, DNA
How have humans disrupted the carbon cycle?
burning fossil fuels and deforestation
Where is carbon stored?
in ocean, soil, and plants
What do plants use carbon for?
to photosynthesize
What is perforation?
holes punched in a landscape
What is dissection?
initial subdivision of a continuous landscape (roads)
What is fragmentation?
breaking up into smaller parts
What is shrinkage?
reduction in size of patches
What is attrition?
loss of patches
What are characteristics of natural patches?
- structure is complex
- habitat is suitable to many species
- less contrast between patches
- edge effects are less intense
What are characteristics of human caused fragmentation?
- structure is simple
- habitat is not always suitable
- contrast between patches is high
- edge effects are more intense
What are underlying causes of fragmentation?
- Agriculture
- urban development
- logging
- mining
- roads
- hydroelectric dams
- dredging
- fishing
What are some edge effects in amazon rainforest?
- increased wind disturbance
- elevated tree mortality
- altered species composition of leaf-litter invertebrates
- reduced canopy height
Characteristics of species vulnerable to fragmentation?
- specialized habitat needs
- limited dispersal abilities
- low fecundity
- vulnerable to hunting
- arboreal
- co-evolved species
- ground nesters vulnerable to predators
What are some birds that thrive along edges?
- ruffed grouse
- turkey
- bobwhite quail
- cardinals
- indigo buntings
- bluebirds
- red-tailed hawks
- brown thrasher
What are some mammals that thrive along edges?
- white-tailed deer
- rabbits
- raccoons
- foxes
- opossums
What is island biogeography?
- relates number of species to distance from mainland and size of island
- larger islands close to mainland have highest species
- small islands far from mainland have lowest species
Who came up with the island biogeography theory?
a theory developed by EO Wilson and Robert McArthur
Is rate of extinction higher for small or large islands?
small
Is rate of immigration higher for islands closer or farther from mainland?
closer
What is a sentinel species?
indicate ecosystem changes that would otherwise be unobserved; typically used to reference environmental hazards
Why was the peregrine falcon (sentinel species) almost wiped out from 1940s-60s
DDT (an insecticide made to combat mosquito populations to prevent malaria); made eggshells brittle
What are some threats the aquatic environment faces?
- sewage release
- fisheries bycatch
- oil spills
- coastline modification
What is biomagnification?
toxic chemicals become successively concentrated at higher levels in the food chain
What is eutrophication?
- excessive plant and algal growth due to increased limiting growth factors in water needed for photosynthesis (often phosphorous)
- animal waste, fertilizers,
What is dieback occurring near power plants?
acid rain causing trees to die
What happened at Lake Okeechobee?
What pH is safe for most fish?
5 to 9
What is the greenhouse effect?
occurs when gasses and water vapor form a blanket around the Earth
- light waves are transformed into infrared radiation (heat) and reradiated
- greenhouse gases in the atmosphere trap reradiated heat near Earth’s surface
What are some natural greenhouse gases?
- water vapor (H2O)
- carbon dioxide (CO2)
- methane (CH4)
- nitrous oxide (N2O)
What is Earth’s atmosphere composed of?
- gases and aerosols (particles)
- 99% of volume is nitrogen and oxygen
What would happen without natural greenhouse gases?
earth’s temperature would be well below freezing
How are greenhouse gases changing over time?
increasing in concentration, CFC’s have been mostly controlled tho (leveled off)
What are chlorofluorocarbons (CFCs)?
- synthetic compounds
- refrigerants, plastics, aerosol propellants, industrial solvants
How harmful are CFCs?
10,000 - 20,000x the impact on global warming as one molecule of CO2
How do biomes contribute to climate change (video)?
- dark conifer forest absorbs light warming surface and grow slowly
- deciduous forest reflects light back to atmosphere and grow quickly
Why is the melting of permafrost a concern (video)?
- twice as much carbon is frozen in permafrost as in the current atmosphere
- when thawed, carbon will start to degrade and be released through respiration into atmosphere
- the Carbon Bomb
How long do CFCs last in atmosphere?
persist in atmosphere for 60-400 years
What does ozone (O3) do?
- naturally occurring
- filters out UV rays
- binds to CFCs and no longer effective at filtering UV (ozone depletion)
Why has emphasis been placed on CO2 emissions?
- it will contribute to more than half of the increase in radiative forcing (greenhouse effect) during next 100 years
- long residence time in atmosphere-ocean system (500 years)
- we know its source and can stop/limit it
How has atmospheric CO2 increased over the last 130 years?
CO2 concentrations in parts per million have increased dramatically as a result of human activities
- now at 427 ppm
- in 1880 was less than 300 ppm
Did we have high concentrations of CO2 before evolution of land plants?
yes
What has atmospheric CO2 been at over the past 20,000,000 years?
100-400 ppm
What have CO2 concentrations been at for the past 2000 years?
between 270 and 290 ppm
What does the Intergovernmental Panel on Climate Change (IPCC) expect CO2 levels to reach by 2050? 2100?
- 500ppm in 2050
- over 700 ppm by 2100
Where will there be the greatest temperature changes?
at very high northern latitudes in arctic, boreal forests
How does warm temperatures affect Net Primary Productivity (NPP)?
- warmer temperatures mean more plant growth
How is increased NPP offset by soil respiration with climate change?
soil respiration doubles with every 10 C rise, so partially negates any warming effects
What are some evidence for climate change/global warming (NASA website and powerpoint)?
- global temperature rising
- ocean getting warmer
- ice sheets are shrinking
- glaciers retreating
- snow cover decreasing
- sea level rising
- shifts in species ranges
- earlier spring activity and flowering of plants
- population declines
Where does added CO2 come from?
burning of fossil fuels
Where does added CH4 come from?
- cattle
- fracking
- landfills
How potent is CH4 compared to CO2?
80x more potent
Where does added N2O come from?
- fertilizers
- waste water treatment plants
When CO2 emissions are reduced, will climate change be better?
- because CO2 persists in the atmosphere, we won’t see any decreases in our lifetime
- CO2 concentration, temperature, and sea level will continue to rise
- will take several hundred years for CO2 and temperature to stabilize
- sea level rising will continue 1,000 years in future
What was warmest year on record?
2024
What contributes to sea level rise?
ice on land melting (sea ice melting does not rise sea level)
What is phenology?
timing of events that occur seasonally in plants and animals
How can phenology be used to protect species?
can predict where a species will be distributed in the future and protect both current and future area
How do bison help combat climate change (video)?
bison naturally instigate processes that increase carbon capture in plants
How can animals be used to combat climate change (video)?
protecting 9 keystone species can offset USA’s carbon emissions
What is the Intergovernmental Panel on Climate Change (IPCC)?
- a scientific intergovernmental body established by the United Nations
- provides an internationally accepted authority on climate change
- bases its assessment on published literature
- thousands of scientists voluntarily contribute to writing and reviewing reports
How many countries participate in IPCC?
over 120 countries
