WELCOME TO THE VERY LAST DAY OF CLASS!
A few important announcements...
1. Come to the Annual GIFFORD ARBORETUM
PICNIC on Saturday,
December 2nd at 1:00pm in the arboretum. Plant sale, Auction of Tropical
Wood (for wood turners and other crafty folk), tee shirts & sandwiches for
sale (help the Arboretum raise $). It's a beautiful and peaceful way to spend
the weekend before the Reading Days!
2. Optional FIELD TRIP TO FAIRCHILD TROPICAL GARDENS this
Friday at 1:30pm! Please meet Dr. Krempels in the Cox lobby at 1:30pm
sharp. We'll be taking the departmental van, and we don't want to leave
you behind!
3. REVIEW SESSION for the final exam will be held on MONDAY,
December 4 at 4:00pm in this lecture hall. Be there with questions! Use your old study guides, old exams and your
notes and text to study for this final exam.
4. LAST CHANCE FOR ANY MAKE UP EXAMS! If you have
missed any of the exams so far, your last chance to take a makeup
exam will be this coming Monday, December 4 (Reading Day) at 2:30pm in room
SA 110 (the lab across the lobby). Format is short answer, fill-in-the-blank, matching, etc.
If you do not take a make up exam, you will have
a "zero" for the exam you missed, and your grade will
be based on your total points.
5. FINAL EXAM will be given on Wednesday, December 13 at
5:00pm in SA 126 (the regular lecture hall). No make up final exams!
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And now, back to our regularly scheduled last
lecture...
The ecological importance of plants cannot be overstated.
They form the basis of all ecosystems.
Plants are the primary source of all fixed energy on the earth that is usable by other life forms.
* Via photosynthesis, they fix carbon into organic forms.
* Via symbiotic relationships with bacteria, they help fix nitrogen into compounds usable by living things.
* They produce all essential nutrients they need
for themselves. Animals can get all their essential nutrients,
including vitamins, by eating plants.
Plants form innumerable symbiotic relationships with
other organisms. A tiny sampling includes...
1. predator/prey relationship between plants and the animals that eat them.
2. nitrogen-fixing mutualism between legume plants and the bacteria in their roots that fix nitrogen into ammonia, nitrite and nitrate (which plants can use to make DNA, RNA and protein)
3. mutualism with mycorrhizal fungi: The fungi form a connection with the roots of the plant and spread out over a vast area of the forest floor. The fungus partner gets sugars and amino acids from the plant's photosynthesis. The plant gets increased water and mineral absorption from the fungus. Without mycorrhizae, plants are stunted and don't live very long. (Not all species of plants have mycorrhizal partners, but we are finding fewer and fewer plant species that DON'T have them!
4. Plants produce oxygen during the noncyclic photophosphorylation. They are the source of the vast majority of oxygen gas in our atmosphere.
5. Plants create local humidity via transpiration that fosters rainfall. Without them, rainfall decreases and drought can ensue.
6. Plants form a vital link in all the biogeochemical cycles on earth! All elements and inorganic compounds move through living and non-living components of the earth. See Figure 25.6, page 453 of your text to view THE NITROGEN CYCLE. See Figure 25.7 to view THE CARBON CYCLE. These are common sense, but it's very important that you understand them!
7. Because they are such large reservoirs of carbon,
plants are a vital buffer against Global Warming, which is NOT
the same as The Greenhouse Effect.
Greenhouse Effect: the warming of the earth's atmosphere
due to the reflection of solar radiation by atmospheric gases
such as carbon dioxide, methane (CH4) and ozone. It
allows life on earth to survive. Without it, earth would be a
cold, lifeless rock.
Global Warming: an anthropogenic (human-caused) phenomenon caused by the very rapid release of greenhouse gases via
* burning of fossil fuel (which was once plants!)
* cutting and burning of forests
* overproduction of cattle (BIG methane producers!)
The carbon so long sequestered in the above systems
is released into the atmosphere, causing a rapid increase in Greenhouse
Effect. This can result in melting of water that is normally frozen
(such as at the polar ice caps) and a resulting rise in sea level.
Buy your waterfront Arizona property now!
BIOMES - These are the major biogeographical realms
of the earth, and are basically defined by the type of vegetation
that lives there. The vegetation, in turn, is determined by the
climate, which affects local topography as well.
Reading assignment for the final: pages 460 - 467. Be sure you are familiar with the characteristics of the major biomes listed! (There are others, so be happy!)
From north to south:
1. Tundra (primarily above the Arctic Circle)
Characterized by permafrost--permanently frozen ground--which prevents the growth of large trees with deep root systems.
2. Taiga (also known as Boreal Forest)
Dominated by conifers
3. Temperate Deciduous Forest (dominated by deciduous (seasonally leaf-shedding) anthophyte trees.
4. Grassland (also known as prairie or savannah) - Dominated by annual grasses and herbaceous plants that live for one year, flower and then die, to be replaced by their seed-born offspring.
(Note: an annual plant is one which lives, flowers and dies over the course of one year. A perennial plant is one which persists and flowers year after year)
5. Desert (dominated by xeriphytes such as cactus)
6. Montane (mountain) forests (These are "refuges" of past taiga which no longer exists due to global climatic change. They live only at high elevations, which tend to "mimic" more northern conditions. Conifers have an advantage here!)
7. Tropical Rainforest - The most ancient, most diverse and most stable of all biomes, this is also rapidly disappearing (at a rate of about 100 acres per minute!) This is a major source of Global Warming.
MORE THAN 50% OF ALL KNOWN SPECIES OF LIVING ORGANISMS LIVE IN THE TROPICAL RAINFOREST. DESTROY IT, AND THEY WILL BE GONE FOREVER.
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But do not despair. You think there's not much one person can do? Think again, as you watch the Academy Award winning short,
Good luck on the final! See you at the review!