Lecture 2 - DA Flashcards
What defines a woodland?
Trees with non-overlapping crowns.
What defines an open forest?
Tall trees giving only a single stem.
Where are forests usually localised? What about woodlands?
Forests are near coastlines.
Woodlands take transition zone between forests and grasslands/shrublands.
How tall are trees in woodlands, generally?
10-30m
What is the canopy and spacing of trees like in woodlands? What about their branching?
Large, open canopy.
Trees are widely spaced, and have more extensive branching.
What 3 factors shaped most woodland communities?
Fire, climate, and human activity.
Which biome is the most endangered and vulnerable in Australia?
Woodlands.
What percentage of Australia is an open forest currently? What was it like in precolonisation times? Where are open forests confined to?
5%, confined to higher rainfall areas near the coast.
Current cover is only 60% of precolonisation times.
What are open forests dominated by?
Eucalypts.
Where are Australian alps found?
Southeast Australia only.
What are 2 ways plants can be sampled? What do they record?
Done by pins, or by eye.
Will record species, density, and cover/abundance.
What are 4 methods of surveying an ecosystem?
Transects
Quadrats
Plotless sampling
Aerial survey
When sampling plants vs animals, what is one advantage of plants?
Plants are static.
What are recordings of plant species during a survey specific to? Is this true of animal species?
Time of the recording, some plants can be seasonal.
Some animals come out at certain times only, such as nocturnal animals.
When is a structural survey done?
When comparing different geographical regions.
What does a structural survey reveal? Is it necessary to identify species?
Shows a mix of trees, shrubs, or ground covers.
No need to identify species.
What can a structural survey allow you to compare?
Allows for site comparison, even if species differ.
What are 2 disadvantages of structural surveys?
Not very informative
No record of the species
What is a presence/absence survey?
A list of species, recording all those found.
Name 5 disadvantages of a presence/absence survey.
- Hard to be thorough
- Time intensive
- Seasonal changes means needing >1 visit
- High cost
- Difficult to have accurate identification
What is a density survey?
Counting the number of individuals per area.
What are 2 problems with a density survey?
Defining an area
Defining an individual - especially plants, such as moss or multistems.
What is a cover/abundance survey?
Estimation of the proportion of area covered by a species.
What is an advantage of a cover/abundance survey? What 2 organisms is it good for?
They are quick.
Good for plants, and colonial animals.
What are two disadvantages of a cover/abundance survey? Are they objective or subjective?
Variation between individuals - subjective
Time consuming - objective
What is a solution to the disadvantages of a cover/abundance survey?
Use standardised broad scales.
When are transects used? How are the samples taken?
Used if there are obvious patterns or clines.
Systematic samples are taken along the transect.
How are samples taken if there are no obvious patterns?
Use random points.
What is needed to average out the variability of sampling using a quadrat?
Using a large number of quadrats.
What are the axes of a graph from a quadrat’s results?
Mean no. of plant species per quadrat vs quadrat area.
What are nested quadrats?
Small quadrats that progressively get bigger, within a large master quadrat.
What are quadrats good for?
Understory and midstory.
Plotless sampling is also known as?
Point-quarter sampling.
What is plotless sampling mainly used for?
Trees with scales too big for quadrats.
What does plotless sampling measure?
Individual counting to measure density.
Density in plotless sampling is obtained from 2 measurements. Describe them.
Point-to-plant distance using tapes/measures.
Diameter at breast height over bark - dbhob
-Also circumference at breast height
How is plotless sampling carried out?
From a random point, divide the area to 4 quarters.
Measure distance to the nearest individual of species in each quarter, and average it.
Do the same with DBHOB, to get its average.
Allows calculation of density and dominance.
What does DBHOB allow you to estimate? How is canopy cover usually estimated in plotless sampling?
Canopy cover. Cover is assessed visually.
Describe the braun-blanquet cover abundance scale.
+ 1 2 3 4 5
+ - sparse, very small cover
5 - >75% cover
What are aerial surveys good for? What is needed in addition to an aerial survey?
Good overview, reveals patterns if there. Will need to visit the area however, to confirm findings.
What is a berlese funnel, what is it used for, and how does it work?
A trapping method for invertebrates.
A known area of litter is collected, spread on a mesh, with mild heat applied.
Invertebrates within will fall through the mesh to escape, and fall to ethanol below.
The individuals can then be counted.
