CENTRE FOR FOOD TECHNOLOGY AND RESEARCH (CEFTER)
AKPERAN ORSHI COLLEGE OF AGRICULTURE,
YANDEV
QUADRAT CONSTRUCTION
BY
1Ukoro F. O.,
1Department
of Basic Sciences, Akperan Orshi College of Agriculture, Yandev, Gboko
CHAPTER
ONE
1.0
INTRODUCTION
A quadrat is a plot used
in ecology and geography to isolate a standard unit of
area for study of the distribution of an item over a large area. While
originally square, modern quadrats can be rectangular, circular, irregular,
etc., The quadrat is suitable for sampling plants, slow-moving animals (such as millipedes and insects), and some aquatic organisms.
When an ecologist wants to know how many organisms
there are in a particular habitat, it would not be feasible to
count them all. Instead, they would be forced to count a smaller representative
part of the population, called a sample. Sampling of plants or animals that do
not move much (such as snails), can be done using a sampling square called a
quadrat (Dodd, 2011).
A suitable size of a quadrat
depends on the size of the organisms being sampled. For example, to count
plants growing on a school field, one could use a quadrat with sides 0.5 or 1
metre in length. Choice of quadrat size depends to a large extent on the type
of survey being conducted. For instance, it would be difficult to gain any
meaningful results using a 0.5m2 quadrat in a study of a woodland canopy (Krebs,
1999).
It is important that sampling in
an area is carried out at random, to avoid bias. For example, if you were
sampling from a school field, but for convenience only placed quadrats next to
a path, this might not give a sample that was representative of the whole
field. It would be an unrepresentative, or biased, sample. One way one can sample randomly is to place the quadrats
at coordinates on a numbered grid.
Long-term studies may require
that the same quadrats be revisited months or even years after initial
sampling. Methods of relocating the precise area of study vary widely in
accuracy, and include measurement from nearby permanent markers, use of total station theodolites, consumer-grade GPS, and differential GPS (Wheater et
al., 2011)
1.2
STATEMENT OF THE PROBLEM
This
research now show benefit on the aspect of an ill-equiped laboratory in the
areas of ecology. Absence of this constructive material in teaching and
learning may cause poor learning habit in the laboratory. Without this simple
instrument problem may arise while handling Ecology course.
1.3 THE
AIMS OF THE STUDY
i. To construct a simple square
frame quadrat of 20m by 20m for the purpose of evaluating and counting plant
population within an area of studies.
ii. To determine the effect of
this instrument the study of plant population in a given distributions.
1.4 SIGNIFICANCE OF THE STUDY
Constructing this simple
instrument would ease any ecologist in the aspect plant and animal population
study. Thereby knowing their abundant in a given distribution within a
population.
1.5 LIMITATION
Few of the said instrument will
be constructed due to financial constrain.
CHAPTER
TWO
2.0
LITERATURE REVIEW
2.1 Plant
Frequency Sampling for Monitoring Range lands
Federal
and State land management agencies in Nigeria. are actively involved in
monitoring the effects of management practices and climatic fluctuations on
range lands. A widely used method for monitoring vegetation changes on these
range lands is plant frequency sampling. Frequency has become popular primarily
because it is relatively simple and objective (Greig-Smith 199).
2.2 Sampling Procedures
2.2.1 Quadrat Size
Quadrat
size is an important consideration in quadrat frequency sampling. The size of
the quadrat influences the probability of each species occurring within the
quadrat. Small quadrats result in low frequencies for most species and many
uncommon species will not be sampled except with large samples. Large quadrats
will include most species but will include the most common species in every
quadrat. This eliminates the ability to detect changes in abundance or pattern
for those species (Brown, 1999).
The
choice of a suitable quadrat size is primarily a function of the average
abundance per unit area. A change in the size of the quadrat usually has the
most effect on frequency values for species of intermediate abundance. Less
influence of quadrat size is noted for species of high or low prevalence
(Mueller-Dombois and Ellenberg 1974). Frequency values of 100% indicate quadrat
size exceeds the maximum size of gaps between individuals (Daubenmire 1968). If
quadrat size greatly exceeds this, then even a considerable decrease in the
relative abundance of the species will not be detected. The best sampling
precision is reached for a particular species when it is present in 40% to 60%
of the quadrats sampled. This will provide the most sensitivity to changes in
frequency. Good sensitivity is obtained for frequency values between 20% and
80%. Frequency values between 10% and 90% are useful but data outside this
range should be used only to indicate species presence. Ideally, each plant
species should be sampled with a quadrat size best suited for it. Obviously
this is impractical. As a compromise, a quadrat size is selected which will
adequately sample as many species as possible. Generally, quadrat size should
be kept as large as possible without frequency of the most abundant species
approaching 100%. At the very least, sampling those species in which one is
most interested should result in frequency values between 20% and 80%.
2.2.2 Quadrat Shape
Numerical
results of frequency sampling are also dependent on quadrat shape, though to a
lesser extent than size. Therefore, as with quadrat size, the same quadrat
shape must be used for all sampling for which data are to be compared. Any
conventional quadrat shape will provide satisfactory results (The term
"quadrat" is loosely defined here to included circular sample units).
However, there are some considerations.
Since
individuals of a species tend to be symmetrical and often concentrate in
patches, a rectangular frame is likely to assess a somewhat different frequency
than an equally sized square or circular frame (Dodd, M. (2011).
For sampling most vegetation parameters, a
rectangular frame is generally considered the best shape because it least
conforms to plant shapes and distribution patterns and samples more variability
with each placement of the frame. However, a rectangular quadrat has a longer
perimeter than a square or circular quadrat of equal area. Therefore, in
frequency sampling, more judgement error is introduced in deciding if a plant
is in or out of the quadrat boundaries. A circular frame has the least
perimeter per unit area, but is probably the least preferred because the frame
shape conforms to plant shape and distribution patterns. Also, a circular frame
can be less practical in the field because one side cannot be left open to
facilitate placement and still have plot boundaries easily defined. A square
quadrat is recommended as a good compromise.
2.2.3 Basis For Recording Presence
The
most common criteria for determining plant presence within a quadrat are a)
rooted or basal frequency for which a plant must be rooted within the quadrat,
and b) cover or shoot frequency for which a species is counted as present if
any part of the plant hangs over or occurs within the bounds of the quadrat.
Some
have distinguished rooted and basal frequency by defining rooted frequency as
using the center of a stem or clump as the criterion of inclusion, and basal
frequency as considering any part of the stem or clump. In practice, the
distinction is rarely made. Generally, a plant is recorded as present if any
part of the plant is rooted within the quadrat. Stoloniferous plants require
some judgement as to whether to include rooted nodes or not. Rooted nodes are
generally included because it is easier to be consistent and because an
individual plant can develop from a rooted node in the event the stolons are
severed (Greig-Smith, 2008).
2.2.4 Sample Size and Design
Experience
with frequency sampling has shown that vegetation changes often occur as
relatively large changes. Regular frequency measurements can provide the signal
that a change has occurred, and field observation can determine if the signal
is biologically realistic.
The
number of quadrats to be sampled depends upon the objectives of the sampling
and is usually determined as a balance between a practical number which can be
sampled on a regular basis and a number which is statistically sensitive to
changes. Two hundred quadrats appears to be a reasonable compromise between
data needs for statistical rigor and needs to identify biologically meaningful
changes. Generally, it is better to take samples of this size on a regular
basis than to undertake a more ambitious sampling program which dies because
too much effort is involved. One hundred quadrats is the minimum number
recommended at each sample location. If frequency data are analyzed strictly on
a statistical basis and the objective is to identify small magnitudes of change
with a high degree of probability, large samples of 500 to 1000 quadrats may be
required (Hironaka, 2009).
Sampling
design or arrangement of quadrats at a sample location or macroplot also is a
matter of both statistical validity and practical application. Frequency data
are enumeration data (presence or absence) and are discrete. Such data fit a
binomial population distribution and statistical analyses may utilize binomial
confidence intervals or Chi-square analyses. The sampling unit in this
situation is the individual quadrat and strict statistical theory requires that
each quadrat be independent and randomly located within the macroplot. The
macroplot may be divided into a limited number of blocks and each block sampled
with random placement of quadrats.
If
normal statistics (t and F tests) are used to evaluate the statistical validity
of differences among blocks within macroplots, years or sample areas, a
sampling design which groups quadrats into transects may be used with the
transect mean or total used for analysis. In this case, data are continuous and
transect means should approach a normal distribution. The design should
maximize the number of transects (to maximize the number of degrees of freedom
for error) but should include enough quadrats in each transect so that few
transects have zero values for any species of interest. For 200 quadrats, 10
transects of 20 quadrats each is often a reasonable choice (Hyder, et al. 2010).
2.3 Appropriate Use of Frequency for Range
Monitoring
Each
parameter sampled and each method used to sample it have their advantages and
disadvantages and have purposes to which they are most suited. The same is true
of frequency data. Plant frequency data are useful because they are relatively
easy and fast to collect, can be statistically evaluated, and indicate changes
in species abundance and distribution. Because frequency data are non-absolute,
they only indicate a change is occurring and which species are changing. The
nature of those changes is not very well established from frequency data alone.
Frequency
is an appropriate "indicator" of range trend, but unwarranted
conclusions should not be drawn from frequency values alone. Other parameters
provide more information than frequency alone and should be used where
necessary. Frequency combined with other parameters is especially useful.
However, other parameters are more expensive to obtain and are not always
practical for wide spread monitoring (Hyder, et al., 2011).
A good
analogy has been used to describe the appropriate use of frequency monitoring.
A doctor monitors a patients blood pressure for indication of heart problems.
When an increase in blood pressure is detected, the doctor does not immediately
perform open heart surgery. Rather, additional tests are run to confirm and
pinpoint the cause of the rise in blood pressure. Then appropriate action is
taken.
Frequency
monitoring should be considered in range management in a similar way as blood
pressure monitoring is used by a doctor. When a consistent change in frequency
of one or more species occurs, it may be necessary to take a closer look to
determine the nature and cause of those changes. This may require performing
additional "tests" such as more intensive monitoring of additional
parameters. Lack of consistent trends in frequency values indicates little
change in the vegetation and efforts can be concentrated elsewhere where
frequency values are changing.
Frequency
should be used only in those vegetation types and situations where it is
appropriate. Results should not be inappropriately extrapolated beyond the
location sampled.
2.4 Comparison with Other Monitoring Methods
How
does frequency sampling using quadrats compare with other methods commonly used
to monitor range lands? There is not as much difference as it may seem for many
of these methods. Some of the most common methods used by range managers now
and in the past can be compared with frequency to assist in understanding use
of the method. Also, the use of ground cover sampling popularly included with
frequency sampling will be briefly discussed (Cochran, 1998).
2.4.1 Point Methods
Various
"point" sampling procedures, such as the "step-point" and "Parker
3-step" methods, have been used extensively by land management agencies
for monitoring trends in range condition. The basic concept behind these
procedures is essentially the same as that of quadrat frequency except that a
point is used as the sample or sub-sample unit rather than a quadrat. In fact,
data collected with point sampling methods can be evaluated as frequency data;
i.e. the number of hits on a plant species as a percentage of the total number
of points read. However, because a point is essentially dimensionless, the data
are usually used as absolute measures of cover, basal area or whatever the
criteria used for determining "hits" (Krebs, 1999).
There
are advantages to the direct quantitative information provided by point
procedures as opposed to the relative nature of frequency data. However,
disadvantages of point sampling often out-weigh the advantages. The main
disadvantage of point procedures is the large number of sample points usually
required for an adequate sample size. Large sample sizes are required because
many placements of the point encounter no plants at all.
Another
disadvantage of point methods relates to lack of repeatability over time and
between observers. It is difficult to place a point without any bias. The
slightest shifting of a point may change the reading and two observers may see
it differently anyway (Mueller et al., 1995).
2.4.2 Point Frame
One
approach that is occasionally used to help overcome disadvantages of point
sampling is to place a series of pins in a frame. These "point
frames" allow for rapid sampling of points by providing several sample
points at each placement of the frame. At the same time, the pins are held
rigid in position such that there is less bias in the placement of the pin for
sampling. The main drawback to this approach is that the sample points within
each group or frame placement are so close together as to lack independence. In
other words, the points are not independent of each other as related to size of
a plant or patterns of plant distribution. For example, all or a portion of the
points in the frame may hit the same shrub. This can cause biased sampling
results with the principal bias in favor of large or aggregated species
(Parker, 1991).
2.4.3 Step-Point
Another
common attempt to remedy the drawbacks of point methods is to record the
nearest plant to the sample point whenever a direct hit is not made. This gives
a recorded hit each time the point is placed, reducing the number of points
that must be sampled and reducing observer inconsistencies or errors in reading
the hits.
This
approach has several problems stemming from the fact that the method is not
really a point method. It is a quadrat based frequency method except that the
quadrat varies in size with each placement of the point (quadrat). The size of
the quadrat at each placement is determined by the distance to the nearest
plant. The quadrat is circular in shape, or a half-circle when only plants in
front of the point are considered (such as when the tip of the boot is used as
the point). If the closest plant is determined based on any plant part, it is
cover frequency. If the criterion is the closest plant at its rooting point, it
is rooted frequency (Raunkiaer, 1999).
There
are three problems with nearest plant frequency data. First, each
"quadrat" is of a different size such that the data have no meaning
until combined for determining composition. Second, when composition is
determined, the data for each species are no longer independent. A change in
the density of one particular species will cause a change in data values for
other species regardless of whether the abundance of the other species has
changed or not. This means it is impossible to determine which species are
changing and whether they are increasing, decreasing, or some of each. Third,
small, dense species such as some grasses and small annual forbs are greatly
overemphasized (RISC , 1990).
2.4.4 Parker 3-Step
The
Parker 3-step method (Parker 1951), widely used by the USFS, is another attempt
at overcoming disadvantages of point sampling. In the Parker method, the size
of the "point" is increased to 3/4 inches in diameter to reduce error
in determining hits. The "point" is kept consistent in size and is
kept small so that the data can be evaluated as cover data. Increasing the size
of the "point" such that it has dimensions creates a bias in the data
when interpreted as cover data. Thus, an estimate of cover by the Parker method
is considered a biased estimate of cover. This bias is generally not considered
high enough to cause significant problems in interpreting the data, although at
times it can be significant.
A
major disadvantage of the small 3/4 loop used in the Parker method is that
although slightly increasing the size of the "point" helps increase
repeatability in sampling, it does not greatly reduce the sample size required
for adequacy of sample. The 300 points typically sampled are often inadequate.
Since
only species presence or absence is recorded, data collected with the Parker
method using a 3/4 loop can appropriately be analyzed as frequency data.
However, the 3/4 inch loop is too small for most species to be useful for frequency
data (Smith et al., 2012).
2.4.5 Ground
Cover
A
popular addition to monitoring plant frequency has been point sampling of
ground cover. Usually, one or more points are marked on the quadrat frame. At
each placement, the type of ground cover occurring beneath each point is
recorded. Cover type categories are usually general, e.g. bare ground, rock,
litter, etc.. Although a reading is obtained at every placement of a point
(unlike plant cover), point sampling of ground cover still often requires a
larger sample size than quadrat frequency. One remedy is to read more than one
point per placement of the quadrat. This results in a clustered sampling and
may result in bias due to lack of independence between points (Hironaka, et
al., 2011).
Ground
cover data are useful, and may also indicate changes in range trend.
Ultimately, ground cover or other soil features may be the best indicator of
long term site stability and potential productivity. However, our current
understanding of what parameters to monitor and how to monitor them is still
limited.
It
should be emphasized that point sampling of ground cover involves a different parameter
and is a procedure additional to, rather than a part of, plant frequency
sampling. Therefore, the proper sampling and evaluation of ground cover must be
considered separately from frequency in (Snedecor, G. and W. Cochran. 1998).
CHAPTER
THREE
3.0
METHODOLOGY
3.1
Research and Study Area
Benue State lies within the lower
river Benue trough in the middle belt region of Nigeria. Its geographic
coordinates are longitude 7° 47' and 10° 0' East. Latitude 6° 25' and 8° 8'
North; and shares boundaries with five other states namely: Nasarawa State to the north, Taraba State to the east, Cross-River State to the south, Enugu State to the south-west and Kogi State to the west. The state also
shares a common boundary with the Republic of Cameroon on the south-east. Benue
occupies a landmass of 34,059 square kilometres. (Annom, 2015)
and minimum daily temperatures of
35 °C and 21 °C in summer and 37 °C and 16 °C in winter,
respectively. The south-eastern part of the state adjoining the Obudu- South
Cameroon mountain
range, however, has a cooler climate similar to that of the Jos Plateau. (Ajaero,
et al. 2007)
3.2 How to Make a Quadrat
Supplies: All supplies can be purchased at your local hardware store
- ¾” Sch (schedule) 40 Ply wood (quantity: at least 2.2 m for each quadrat)
- ¾” 90 degree angle plywood elbows (quantity: 4 per quadrat)
- plywood primer
- plywood glue
- Nylon string (quantity: 5m per quadrat)
- Hack Saw
- Drill and 1/8” drill bit
- Matches, lighter, glue gun or candle
- Meter tape
- Vice
- Hammer and nail
- Tape
- Pencil
- Latex gloves
- Old newspaper
3.4
STUDY POPULATION
The numbers of items under study
were ten (10) after constructions and assembling.
3.7
PROBLEM ENCOUNTERED
The only problem was on the side
of constructing or forming the right and triangle (900). Here lots
of error of omission were observed and were corrected. Transportations tu and
fro becomes too necessary as any error of cut angle has to be return for
readjustment.
3.8
PREPARATION OF MATERIAL
After buying the items, they were
all picked and assembled one by one noting which fit best, before gluing.
Materials:
4 x 1m lengths of half-inch plywood
4 x elbow joints for this wood
The
quadrat was build with a square quadrat frame out of plywood meter sticks. One
method involves fastening sections of the plywood using elbows. To make the
quadrat frame easier to slide under vegetation, you can construct the two
halves separately using plywood and sleeves. Another method used to construct
quadrats is tying 1 m long pieces of string between both ends of two meter sticks.
This method is best for short vegetation as the strings may get caught on
taller plants.
20 cm x 20 cm. quadrat for
sampling
3.8.1 How to Weave the String
i.
Start
stringing the first 2.5 m length of string here. Tie knot, pull tight through
first hole, then continue to string following the arrows.
ii.
Pull string
taught, tie knot, then glue or burn knots at both ends.
iii.
Turn the
quadrat 90 degrees and start stringing the second 2.5 m length of string as
above. Tie knot, then continue to string alternately going over and under the
first length of string.
iv.
Pull string
taught, tie knot, then glue or burn knots.
v.
You’re done!
CHAPTER
FOUR
4.0
RESULT AND DISCUSSION
4.0.1 Recording Data
The
first time a location or macroplot is sampled; ground rules should be clearly
established and recorded for future reference. Later adjustments should
likewise be noted. Ground rules to consider include:
- Criteria for determining presence for each species or life form.
- Which species, if any, are to be lumped together (e.g., annual forbs or species difficult to distinguish such as 3-awns or some gramas).
- Whether to include seedlings and whether to separate any species into age classes. Seedlings, especially for species with low rates of seedling survival, may be excluded from the sampling or tallied separately to avoid wide fluctuations in the data which are season or climate related.
- Are annuals to be recorded, and if so, do they have to be alive and green or dry but rooted and standing.
- Sampling design, including any portions of the site to be avoided in sampling such as inclusions of atypical soil or vegetation.
Generally,
data should be collected on a species by species basis. Consistency in species
identification and use of criteria for determining presence or absence are
essential. Rooted frequency is recommended for herbaceous plants and small
shrubs and half-shrubs. Canopy frequency is suggested for larger shrubs. For
intermediate sized shrubs or half-shrubs, the criteria for determining presence
may depend on shrub density. Often, cover frequency is used for all shrubs in
the interest of simplicity and consistency.
Summaries
of data from previous sampling periods should be taken into the field for
reference to assist in maintaining consistency in species identification.
Having previous years data in the field also helps to interpret causes for
observed changes while at the monitoring site. Recording species observed in
previous sampling periods on field forms prior to sampling helps observers with
consistency in identification. It also helps with on site comparison of current
years data with previous years because species are in approximately the same
order on the data sheets as on previous years summaries (Tueller, 1992).
Perhaps
the most common and significant problem in comparing data over time is in
treatment of similar species. For example, two similar species may be
separately identified on one occasion and combined as one species on another.
Or, attempts may have been made to separate the species on each occasion, but
the data reveal those attempts to be inconsistent. In these situations it is
necessary to combine data for the two species and evaluate them as a complex.
However, this can only be done if the data are collected on a quadrat by quadrat
basis rather than tallied. When both species are recorded for the same quadrat,
credit can be given for only one hit when the data are combined. Therefore,
frequency values cannot be directly summed, but must be redetermined from the
recorded hits for each individual quadrat (West, 1995).
4.1 Analysis and Interpretation
An
emphasis on interpretation of frequency changes while at the site of
measurement has already been suggested. It is important to have data from
previous years in a form that can readily be compared with current year data
while at the monitoring location. A summary of data for the monitoring
location, such as shown in is satisfactory for this purpose and is easily
updated. A major benefit of a monitoring program is the discussion of data at
the collection site by interested parties at the time the data are collected.
Data
should be compared for frequency changes from one year to the next on a species
by species basis. Binomial confidence intervals can be utilized to help
identify the magnitude of changes which indicate a change greater than what
might be expected from sampling variation. For example, the data are from a 200
quadrat sample at the 95% confidence level. Frequency of hairy grama for 1982
is 25% with confidence limits from 19% to 31%. In 1983, frequency of hairy
grama was 36% with confidence limits of 29% to 43%. Confidence intervals
overlap, so the difference could be due to sampling variation. Confidence
intervals do not overlap at a probability of 80%. Statistical analyses of data
for this species are detailed in (Whysong,
G. and Brady W. 1997):
This
change is large enough that observations of this species in the field should be
made to determine if there might be some explanation for the change, such as an
indication of new plants in the system. This was the case in this situation and
a note was made that numerous young plants were observed. That these young
plants probably maintained themselves and additional recruitment occurred is
substantiated in the 1984 data where frequency of hairy grama increased to 49%.
A similar observation was made for plains lovegrass for the 1982-1984 period
These changes were interpreted as a response to summer deferment of grazing in
1981 and 1982, heavy grazing with favorable precipitation in 1983, followed by
summer deferment and favorable precipitation in 1984. It was concluded that the
changes were desirable and that the deferred rotation grazing system,
utilization levels and favorable rainfall were providing for upward trend at
the monitoring location.
As was
pointed out, frequency is a combination of species attributes including
density, dispersion and cover. The relationship of frequency to plant density
is curvilinear. Frequency changes should not be expressed as percentage changes
in density. A change in frequency at low values does not reflect density
changes of the same magnitude as changes at high frequency values (Yavitt,
2009).
4.1.0 Advantages and Disadvantages
As
with all vegetation sampling methods, the frequency approach has both advantages
and disadvantages.
Advantages (Objectivity)
No estimation or subjective evaluation is necessary. The only decisions made by the observer are whether a particular plant is present within the quadrat and the identity of the plant. Objectivity provides better repeatability of results over time and among different observers.
No estimation or subjective evaluation is necessary. The only decisions made by the observer are whether a particular plant is present within the quadrat and the identity of the plant. Objectivity provides better repeatability of results over time and among different observers.
i.
Rapidity
Quadrat frequency is a relatively rapid approach to monitoring vegetation changes with respect to value of the data collected.
Quadrat frequency is a relatively rapid approach to monitoring vegetation changes with respect to value of the data collected.
ii.
Simplicity
Relatively little training or practice is necessary for consistent application of frequency procedures and the data obtained are easily summarized and evaluated.
Relatively little training or practice is necessary for consistent application of frequency procedures and the data obtained are easily summarized and evaluated.
iii.
Low
sensitivity to periodic fluctuations
Rooted frequency data are relatively insensitive to periodic fluctuations in vegetation structure due to grazing or changes in phenology. This is less true for cover frequency.
Rooted frequency data are relatively insensitive to periodic fluctuations in vegetation structure due to grazing or changes in phenology. This is less true for cover frequency.
iv.
No
distinction of individuals
There is no need to distinguish individuals in frequency sampling which can be a problem with indefinite individuals such as sod-forming grasses. This is an advantage only in comparison with density techniques.
There is no need to distinguish individuals in frequency sampling which can be a problem with indefinite individuals such as sod-forming grasses. This is an advantage only in comparison with density techniques.
v.
Function
of both density and dispersion
Frequency values depend upon both the density and the dispersion or distribution of individuals. Therefore, frequency will detect changes in plant distribution as well as abundance. This can also be a disadvantage as pointed out below.
Frequency values depend upon both the density and the dispersion or distribution of individuals. Therefore, frequency will detect changes in plant distribution as well as abundance. This can also be a disadvantage as pointed out below.
4.1.1Disadvantages
i.
Function
of both density and dispersion
Sensitivity of frequency to both density and dispersion can be a disadvantage as well as an advantage. It is difficult to determine which characteristic is indicated by changes observed in the data without supporting data from other parameters. Long term range health is, overall, more a concern of abundance than of dispersion. Frequency data can show significant changes in percentage values where no real changes in abundance actually exist. This problem arises more often when comparing two stands for differences than when observing one stand for changes over time.
Sensitivity of frequency to both density and dispersion can be a disadvantage as well as an advantage. It is difficult to determine which characteristic is indicated by changes observed in the data without supporting data from other parameters. Long term range health is, overall, more a concern of abundance than of dispersion. Frequency data can show significant changes in percentage values where no real changes in abundance actually exist. This problem arises more often when comparing two stands for differences than when observing one stand for changes over time.
ii.
Data
are non-absolute
Though often correlated, frequency does not necessarily relate directly to more concrete parameters such as density, weight, height, volume or any criteria related to the amount of a species present at a location. Species frequency data are not generally useful for evaluating vigor, production, or dominance. This limits the use of frequency to comparisons in space or time such as monitoring trends in abundance related to loss and recruitment (confounded with changes in distribution patterns). Also, different species cannot be readily compared with each other unless their size and structure are similar, or when frequency is combined with other data or knowledge relating to size of the plant.
Though often correlated, frequency does not necessarily relate directly to more concrete parameters such as density, weight, height, volume or any criteria related to the amount of a species present at a location. Species frequency data are not generally useful for evaluating vigor, production, or dominance. This limits the use of frequency to comparisons in space or time such as monitoring trends in abundance related to loss and recruitment (confounded with changes in distribution patterns). Also, different species cannot be readily compared with each other unless their size and structure are similar, or when frequency is combined with other data or knowledge relating to size of the plant.
iii.
Values
dependent on quadrat size
Frequency values are dependent upon the size of the quadrat used in sampling. Therefore, data collected with different sized quadrats are not comparable.
Frequency values are dependent upon the size of the quadrat used in sampling. Therefore, data collected with different sized quadrats are not comparable.
iv.
Not
well suited to larger shrubs
Because of wide spacing of large species, a quadrat large enough to adequate-ly sample these species becomes unwieldy or impossible to use. Use of shoot or cover frequency can often be useful for evaluating shrubs, but where indi-vidual plants are widely scattered, may still be inadequate. The same can be said about uncommon, small species, but the issue of large shrubs is usually more important because of potentially strong influence on the community des-pite fewness of numbers. Quadrat frequency procedures are generally not well suited to shrubland vegetation types such as chaparral or Sonoran shrub types.
Because of wide spacing of large species, a quadrat large enough to adequate-ly sample these species becomes unwieldy or impossible to use. Use of shoot or cover frequency can often be useful for evaluating shrubs, but where indi-vidual plants are widely scattered, may still be inadequate. The same can be said about uncommon, small species, but the issue of large shrubs is usually more important because of potentially strong influence on the community des-pite fewness of numbers. Quadrat frequency procedures are generally not well suited to shrubland vegetation types such as chaparral or Sonoran shrub types.
CHAPTER
FIVE
5.0
SUMMARY, CONCLUSION AND RECOMMENDATION
5.1
SUMMARY OF STUDY
The study was carried out around
July, August, and September, 2016. The Quadrate materials were purchased in
order from the market where available within the confined period.
The aim of the study was to
construct a simple square frame quadrat of 20m by 20m for the purpose of
evaluating and counting plant and animal population within an area of study and
to determine the effect of this instrument in the study of plant and animal
population in a given distributions.
Materials were collected in various available areas and taken to the laboratory for
assembling. The result shows that the instrument was useful to the study of the
course Ecology in the code STB 222 for sub-final year student of Basic Sciences
Department.
5.2 CONCLUSION
Based on the result of the study,
the following conclusions were made, that;
i. Constructed Quadrat for evaluation of plant and animal
population, for Biology Laboratory practical were useful to the laboratory.
ii. The benefit of this Quadrat in Biology unit of Basic
Sciences Department of the laboratory will enhance practical knowledge of both
staff and students.
5.3 RECOMMENDATIONS
Since it was proven that evaluating
population of plant and animal can only be done with 20cmX 20cm simple Quadrat
without which such significance and range practical in field will not be possible.
As a result the following recommendations were made.
i.
It helps the
lab. Technologist evaluate plant and animal population in the study area
ii.
It helps field
work possible.
iii. It
adds to the value to the lab functions
iii.
Government
should construction work in the lab. And makes it compulsory for student to embark
on practical for teaching benefit.
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