exam 1 answers Flashcards
Name 3 of the most important figures in the history of environmental conservation and then
explain briefly what were their particular contributions to scientific and/or philosophical
concepts of environmental conservation
John Muir: Wrote widely and became a well-known advocate for preservation of nature.
Founded the Sierra Club.
Aldo Leopold: wrote “Sand County Almanac” and said we must be “stewards”, i.e managers if
necessary, of nature
Rachel Carson: Popular writer who wrote “Silent Spring” documenting problems of pesticides
which jump-started the environmental movement
(a) You take a trip (and I hope you will one day) down through North America and Central
America to South America. When you reach southern Mexico, you cross the Tropic of Cancer,
which signals your entry into the designated tropics. You might therefore expect to be in tropical
rain forest, but you are not: why kind of biome are you most likely in? Explain how features of
the Earth’s geography and resulting weather generate this biome
You’re in the seasonal
dry tropical forest or savannah biome, caused by migration of the intertropical convergence zone
ICZ) to its northern extent once a year ending a long dry season and bringing intense rainfall
(b) As you get nearer the equator in southern Central America, you begin to find true tropical
rain forests. In terms of the Earth’s climate, explain why you now find yourself in rain forest
You’re getting into the area where the ICZ crosses twice a year –> no long dry season and
two, often extended, wet seasons
(c) Not to deny the conservation value of each of the above 2 biomes, but which is scarcer on
the planet and why?
The former: dry tropical forest, much rarer because it’s more easily
exploitable by humans for ranching and agriculture
Despite knowing that many species, particularly of small organisms, had not been described,
we used to think that the total number of species on Earth was a few million. But Terry Erwin’s
simple experiment 40 years ago in a Panamanian rain forest showed that was probably a way low
underestimate.
(a) Very briefly, what was his experiment, what was its result, and roughly what was his
suggestion for the total number of species
(b) In more recent years, several newly explored habitats and techniques for species
identification have suggested an even greater number of species. Name 3 of these habitats or
techniques
(a)- He insecticided canopy trees and found so
many undescribed beetle species that by a rough extrapolation to all habitats and species, he
proposed that there were 10 times as many species in the world
(b)- Excavation into deep earth envis, exploration of hot sea vents at plate
boundaries, environmental DNA analysis, surveys of microorganismal diversity using genomic
analysis
(a) The biological species concept provides a fundamental concept in defining a species for
conservation practice. But there are several situations or characteristics of populations that make
the biological species concept unworkable. Name 2 of these situations or characteristics and
indicate why these create problems
(1) Asexually reproducing populations –> don’t
“interbreed” so can’t define a species, (2) spatially separated populations that can’t be analyzed
for interbreeding, e.g on two neighboring islands
(b) Conservationists give particular weight to preserving endemic, keystone, and umbrella
species. Define each of these (carefully but briefly!) and give one example of each type of
species
Endemic species: found only within one area: e.g. California Condor: California (until recent
reintroductions)
Keystone species: beavers, which modify the envi so much that it creates whole new niches of
other species
Umbrella species: Species with such large requirements for habitat that if they are protected,
many other species will be protected with them. E.g. wolves: packs need 10s of square miles
Define ecosystem services
Functions or products the envi provides for humans
Describe three different categories of such services and give a specific example in each
category. (c) For 2 examples, one each in two of these categories, indicate how they can be valuated
(measured) and then comment briefly on the validity of these measures
Provisoning: wood
Regulating: forests –> erosion control
Aesthetic: ecotourism
(c)- Wood: weight harvested
Ecotourism: money expended
What are “payments for ecosystem services”? Briefly describe and give an example
Government/corporation pays another entity to maintain its environment for the benefit of
the government/corporation
Define what environmentalists mean by “externalities” when it comes to assessing the
costs or benefits of a particular human activity
Those environmental services affected by
an activity/project that are not factored into a cost/benefit analysis
Explain what would have been the externality in the classic historical example that Garrett
Hardin cited in his “tragedy of the commons
Damage caused by overgrazing a
commons
Name one example of an externality in the current world that would fit Harden’s “tragedy” and
indicate how this case fits his concept
Overfishing that depletes the population and leaves less fish available for others
Habitat loss is resulting in major reductions in organismal populations, but fragmentation
compounds the problem. Give three reasons why fragmentation make the problem worse than
just habitat loss
Edge effects (e.g. ∆ humidity), lower heterozygosity, less habitat
Give 2 general reasons that invasive species are a threat to native biodiversity and then 2
examples of damaging invasive species
kill native species – Emerald Ash Borer,
displace native species – Zebra mussel
