CHAPTER 7: SAMPLING METHODS IN BIODIVERSITY (Quadrats Methods (Quadrat…
CHAPTER 7: SAMPLING METHODS IN BIODIVERSITY
Widely used means to obtain quantitative info about composition and structure of plant communities.
Quadrat methods requires these factors:
Height and density of vegetation present
Quadrat is big enough to include a reasonable no. of plants but not so large that you can't count, identify and measure all the study plants with reasonable time.
table 1.7 pg 48
If sampling an area had plants that are abundant, save time by sampling these species with small quadrats
To sample area effectively , do <10 quadrats for small areas and >100 for large areas
sample plots should make up 10% of total area studied
to determine if enough variety samples, walk through area after sampling and look for species abundant but missed in sample plots.
Be unbiased, do not place quadrats all in most interesting or most accessible sites.
Provide important info in assessment of species diversity. Uses different methods depending on type of species and habitat.
Simple Edge Effects
Occurs when the plant crosses the edge. When the plant that crosses over is counter, this leads to overestimation of population size
Circle is used to lower sampling edge effects. Downside: area of circle harder to calculate than square.
Statistically valid results, plots are randomly located within study area.
Steps on pg 49.
Used to observe changes in environment over a given distance
Quadrats places in line as evenly as possible
Mark Straight line (or transect) through site.
Place Quadrats at equal intervals along line.
Number of small Quadrats joined together
Used in coastal areas to study changes of vegetation over dune systems.
Useful group to study as they are well known biologically and taxonomically and the best ecologically known of any group
Used as an 'indicator species' for their presence, absence or abundance, used to indicate state of environment under consideration E.g in distributed environments, introduced rodents may displace ecological equivalents
Only problem is their secretive nature and nocturnal habits.
If species are hard to identify, look for their droppings, tracks, feeding signs, burrows, food remains and remains of bodies
Try collect part of it or photograph or sketch (refer to field guides)
Quietly walking along tracks at night and listening for tell tale rustlings of mammals in leaves or shrubs.
animal is viewed by powerful hand held torch or spotlight
White light for best detection and red light for prolonged observance (disturbs animal less).
during the day
Animals trapped alive in collapsible aluminium Elliot traps or in wine mesh cage traps with suitable bait
undertaken under Permit from Vic Dep. of Env, Land, Water and Planning
provides most reliable data as actual specimen can be positively identified + other data given (e.g sex and weight)
Downside: interferes with animals lives and should be restricted.
Trapping live animals, then using mark-recapture to estimate their population size
Portion of population captured, marked, released
Later, another portion captured and marked individuals counted
The no. of marked individuals in 2nd samples should be proportional to no. of marked individuals in whole population.
estimate of total population size is obtained by: no. of marked individuals / proportion of markees individuals in 2nd sample
Method most useful when it is not practical to count individuals in the population
Easier to find than mammals
Can be found in mudflats wetlands, parklands and low woodland
Field guides used to identify species
All research or monitoring programs on animal species requires ethics approval to endure the welfare of animals affected is considered, both the species under investigation and other organisms within the broader ecosystem that may be affected.
: Research should have the welfare of the research participants as a goal of any research study
Poverty threatens wildlife conservation as local communities are not included in the decision making processes and have little understanding or reasons why such conservation programs are initiated.
Integrating conservation programs with development of local community is an important aspect of ensuring conservation programs are effective
benefits the local community as there is less need to unwittingly and undermine programs through poaching habitat destruction for live stock and agriculture.
Measuring changes in biodiversity
• sampling methods used for assessing species diversity including grids, transects, different shaped quadrats
(including consideration of edge effects), and mark-recapture