VCE Environmental Science

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The following are the genus names of some of the food plants of the Orange Bellied Parrot, that we will be identifying at Killarney on Monday. Get a picture of each of these plants, so you can identify them on our excursion. Remember to bring a digital camera or mobile phone to take pictures of plants we cannot identify. Other equipment required includes: tape measures, metre rulers, clipboards, pencil, field guides for coastal vegetation and suitable footware for wet ground.

 Sarcocornia
Halosarcia
Sclerostegia – (glassworts)
Chenopodium – (goosefoot)
Atriplex – (saltbushes)
Frankenia – (sea-heath)
Suaeda – (sea blight)
 

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Ecologists and environmental scientists use several different indices to quantify biodiversity. One example is species richness, which is the total number of different organisms present – it doesn’t take into account the proportion and distribution of different subspecies within an area. Another example is Simpson’s Index, which takes into account the number of species present, as well as the abundance of each species. The Simpson’s index represents the probability that two randomly selected individuals in the habitat belong to the same species. The Shannon-Weiner Index is similar to the Simpson’s index in that it takes into account the species richness and the proportion of species within a zone.

Today we will use Simpson’s Index to calculate and compare species diversity from a site before and after sheep grazing. Refer to page 49 in your text books.

The study of any species requires an estimate of their density in different habitats. Scientists use many different methods of measuring density, depending on the size, abundance, behaviour and habitat of the species. Our class used a line transect and quadrats to measure the abundance and cover of different floral species in a grassland reserve. Other methods to measure relative density include:

1. Aerial photographs (eg. herds of moose or other hoofed mammals during migration, flamingos)
2. Capture-recapture (or mark and release)
3. Traps (eg. Elliot traps for small mammals, pit-fall traps for reptiles, light traps for insects, harp traps for bats)
4. Number of fecal pellets
5. Vocalisation frequency
6. Pelt records
7. Catch per unit fishing effort
8. Number of artifacts (nests, pupal cases, burrows etc.)
9. Questionnaires (of hunters and trappers for example)
10. Cover (of plants)
11. Feeding capacity (amount of bait taken)
12. Roadside counts

Each method has it’s advantages and disadvantages and is most valubale when used as an adjunct to more direct methods.

Reference: Charles J. Krebs (1985) “Ecology – The Experimental Analysis of Distribution and Abundance” Harper International, New York.