Q 2: Lab Flashcards
Methods for the purpose of quantitative description(5)
- Cover- i.e, what area does each species cover
- Frequency of occurrence
- Density or number of individuals per unit area
- Biomass or weight per unit area
- basal area
flora
is a list of plant species that occur in a given area where the order of species is related to ease of use.
Ex: Alphabetical order
A flora gives no indication of the importance or abundance of the species present.
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. The first species in a vegetation list will be the species that has been assessed to be the most abundant or important to the area usually using one of the above measures.
Can be expressed as an absolute measure such as density(# of individuals of a species per unit area) or relative value, usually in percent, such as relative density(density of species X/total density for all species present).
The text has a good discussion of the development of “Importance Values” for species comprising a plant community.
most common technique for measuring plant abundance generally involve…
…setting up a series of straight lines, either parallel or perpendicular(produces a grid system) to one another, in the study area.
This is called “Transects”
The sample reference frames are called:
quadrats
____ can be square, rectangular, and pretty much any other shape other then a circle which is a bounded area.
quadrats
Quadrat size for Moss, Lichen=
0.1- 0.25 m2
Quadrat size for Grasses and forbs
0.25- 2 m2
Quadrat size Shrubs
10- 15 m2
Quadrat Size Trees
100- 150 m2
A point intercept method cannot generate _____ _____.
density data
where do you measure the diameter of Trees basal area?
Areal Cover:
DBH= Diameter breast height 1.5 Metres above the ground.
LAI
Areal Cover:
Leaf Area Index=
.the ratio between total leaf area above the soil surface and the soil surface area.
. Can range from “0” in true desert or “5” in tropical rainforest
.Strongly related to the availability of Photosynthetically Active Radiation(PAR) at any given level within the vertical structure of the plant community.
PAR
Areal Cover:
Photosynthetically Active Radiation=
.How sunlight is soaked up as it goes down vertical stratification.
. See Text(pg.59-2)
Types of Data: 4
- ) Areal Cover
- ) Frequency
- ) Density
- ) Biomass
Areal Cover
Under the criterion of area are included all those methods that take into account- either by estimate, exact measurement, or some related function- the amount of ground covered by individual species and by the whole vegetation.
Areal cover can be defined as the vertical projection of the above-ground parts of each plant onto the ground.
Frequency
related to the number of times a species occurs in a given number of repeatedly placed small sample plots or sample points.
can be distributed randomly, for example, by throwing a metal ring, or systematically by following a regular patterns.
The species are recorded without regard to their quantity or number of individuals.
For comparing different communities, frequency is best expressed as a percentage of the total number of placements, i.e, the frequency percentage of frequency index.
2 types of 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.
______ is the most commonly applied quantitative parameter for the analysis of forest undergrowth and herbaceous communities in North American description studies.
Frequency
Rooted frequency
Rooted Frequency= records a species being present only when it is actually rooted in the quadrat.
Shoot Frequency
Shoot frequency= obtained by recording as present all foliage overlapping into a quadrat.
Density
define, characteristics, and difficulties
refers to the number of individuals per unit area usually obtained by a simple count of plants in a series of random quadrats.
.extremely time consuming but extremely accurate
. Suitable for early stages of colonization, ex: stabilization of sand dunes and denuded land undergoing vegetation or recovering after abiotic factors.
Difficulty:
- Recognition of individuals
- Difficult to decipher where one individual begins and one ends
- Rhizomatous and Stoloniferous forms can hardly be counted.
- boundaries may spit shrubs
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 60C until a constant dry weight is achieved.
- can be extremely time consuming
- requires extensive record keeping
- Biomass is relatively accurate and generally used in studies where energy within the ecosystem is being examined as biomass represents stored energy.
- Can be used to measure energy flows in ecosystem
Braun-Blanquet scale of cover-abundance(6)
5- covers >75% 4- covers 50-75% 3- covers 25-50% 2- covers 5-25% 1 - covers <5% \+ - present but with very little cover