Lab 5 Flashcards
flora
a flora is a list of plant species that occur in a given area where the order of species is related to ease of use.
A flora gives no indication of the importance or abundance of the species present.
Vegetation
A vegetation is a list of plant species that occur in a given area where the order of species is related to importance or abundance of each species present.
quadrats can be almost any shape but _____,____,____ are most common
quadrats can be almost any shape but circles, squares and rectangles are most common
Quadrat sizes for different vegetation:
Moss, Lichen
Grasses and forbs
Shrubs
Trees
Moss, Lichen - 0.1 to 0.25 m^2
Grasses and forbs - 0.25 to 2 m^2
Shrubs - 10 to 15 m^2
Trees - 100 to 150 m^2
A point intercept method cannot generate _______
density data
Areal Cover
Areal cover can be defined as the vertical projection of the above-ground parts of each plant onto the ground.
Many ecologists have emphasized cover as being of greater ecological significance than _____
density
Cover gives a better measure of plant biomass than does the ________
number of individuals
What is used to determine Leaf Area Index (LAI)
Cover
Leaf Area Index (LAI)
The ratio between the total leaf area above the soil surface and the soil surface area.
As there can be more than one layer of leaf material over the same soil surface, LAI can range from close to 0 in true desert to almost 5 in tropical rainforest.
PAR
Photosynthetically Active Radiation
PAR in a forest
In a forest the trees have access to all the available PAR while the shrubs receive only the PAR that has not been absorbed or reflected by the canopy leaves.
How is frequency best expressed for comparing different communities?
frequency best expressed as a percentage of the total number of placements, i.e. the frequency percentage or frequency index.
frequency provides an __________ but it is a non-________ measure.
frequency provides an objective assessment but it is a non-absolute measure.
Sources of error in frequency estimates
- Size of quadrat
- size of the individual plant
- spatial distribution of individuals
Types of frequency
Shoot frequency
Rooted frequency
Shoot frequency
obtained by recording as present all foliage overlapping into a quadrat
Rooted frequency
records a species being present only when it is actually rooted in the quadrat.
Which is the most common applied quantitative parameter for the analysis of forest undergrowth and herbaceous communities in North american description studies?
Frequency
Density
Density refers to the number of individuals per unit area usually obtained by a simple count of plants in a series of random quadrats.
The process is extremely time consuming but is also extremely accurate allowing different direct comparisons of quadrats in different areas.
it is suitable for early stages of colonization
Difficulty of using density estimates
The recognition of individuals. In spreading shrubs it is often difficult to decide where on individual begins and another ends. Also rhizomatous and stoniferous forms can hardly be counted accurately. Another difficulty is the marginal effect of the quadrat.The quadrat boundaries may go through an individual and a decision has to be made whether to count it or exclude it.
Biomass
The term biomass refers to the total dry weight of biological material per unit area and is usually obtained by harvesting plants in a series of random quadrats. These plants are then dried at 60 degree C until a constant dry weight is achieved.
Biomass represents stored energy and biomass data is relatively accurate in most instances and is generally used in studies where energy within the ecosystem is being examined.
