The Impacts of Canopy Cover on Species Abundance in a Woodlot Habitat

Methods

This experiment was
conducted by Setareh Rezvani, Khondoker Sadid, Arian Nouraee and Ellora
Arockiadoss on a windy day with a climate of 7° C in the woodlot (43.768756,
-79.5079) at York University on Monday October 24, 2016 at approximately 3:00
PM.

Survey method, quadrats: The
quadrats, each sized to 1 meter by 1 meter, were placed every 2 meters along a
50 meter transect placed at random throughout the forest. For each replicate,
the quadrat was placed either on the left side of the transect for odd quadrat
replicate numbers, or right side for even quadrat replicate number. First, the
number of individuals belonging to species native to the site was counted
(native abundance), followed by a count of the number of species that are
exotic to the site (exotic abundance), and lastly the number of flower heads
present in each quadrat. Native and exotic species were identified and
differentiated with help from the experiment supervisor (TA). This was repeated
for a total of 25 times replicates up to the entire length of the transect.

Survey method, transect: A
50 meter transect was obtained and placed from one end of the woodlot to the
other. At every two meters, the abundance of woody plants that was within 0.5
meters on either side of the transect was recorded. Additionally, the canopy
coverage, vegetative ground coverage, and total number of flowers were also
recorded at 2 m intervals on the transect. A total of 25 replicates were
obtained in this data set.

 Survey method, point survey: Using the 50
meter transect, the abundance and species of vertebrates, as well as the number
of humans that did not belong to the lab was collected within a 50 meter radius
of the woodlot over a span of 15 minutes. Additionally, the abundance of
invertebrates was collected within a 5 metre radius in the woodlot area over a
span of 15 minutes.

 Survey method, pan trap: Using the 50 meter
transect, six solo bowls were set 3 meters apart at distances of 0 meters, 3
meters, 6 meters, 9 meters, 12 meters, and 15 meters parallel to the transect.
The six yellow, blue and white bowls in alternating colours were then filled
with soap water to about ¾ full and were left undisturbed for 45 minutes.  At the end, the number of insects present
within the bowls were accounted for within the woodlot.

 Survey method, sweep net: A 50 meter transect
was placed. Using a sweep net, the number of invertebrates captured along the
50 meters was measured and recorded. After the first measurement, the remainder
of the calculations were walked in distances of 1 or 2 meters away from the
transect but continued 50 meters parallel to the transect. This procedure was
conducted in the woodlot for a total of 10 replicates at each area.

Metadata:

Native abundance is a
discrete variable that provides the total number of individuals observed within
the area of the quadrat belonging to species that have been identified as
native to the site being studied.

Exotic abundance is a
discrete variable that provides the total number of individuals observed within
the area of the quadrat belonging to species that have been identified as
exotic to the site being studied

Abundance of woody plants is
a discrete variable that provides the number of woody plants found in each
sample replicate. A woody plant is defined as a tree greater than 1.5 meters in
height.

Canopy cover is a continuous
variable that provides the percentage of canopy coverage that was observed when
looking towards the sky in each sample replicate.

Ground cover is a discrete
variable that provides the percentage of vegetative ground cover in each sample
replicate. Vegetative ground cover was visually identified as grass.

Number of flowers is a
discrete variable that provides the total number of flowers in each sample
replicate. Flowers were identified as any plant with a blooming bud.

Abundance of vertebrates
(eg. birds, squirrels, rabbits) is a discrete variable that measures the number
of individual vertebrates in a 50 metre radius over a period of 15 minutes.

Vertebrate species is a
discrete variable that shows the number of different species that were observed
in a 50 metre radius over a period of 15 minutes.

Abundance of humans is a
discrete variable that provides the number of human beings which were
visualized within a 50 metre radius over 15 minutes.

Abundance of invertebrates
is a discrete variable which accounted for the total number of insects such as
ants, flies, bees and dragonflies that were found in each sample within a 5
metre radius over a 15 minute period.

Abundance invertebrates pan
traps is a discrete variable that represents the number of invertebrates
captured in the solo bowls filled with soap after 45 minutes.

Abundance invertebrates
sweeps is a discrete variables is a discrete variable that represents the
number of invertebrates captured in the sweep net along a 50 m transect.

Hypothesis:
There will
be higher abundance and diversity of wooded plants than herbaceous plants in
the woodlot area due to the lack of sunlight filtering through the dense canopy
cover (less light for herbaceous plants). This leads to amensalism between
herbaceous and wooded plants, as herbaceous species are negatively affected by
the presence of wooded plants, while wooded plants are unaffected by herbaceous
plants.

Predictions
1.    Abundance of herbaceous plant species
will be lower than wooded plants in the woodlot
2. As canopy
cover in the woodlot increases, abundance of herbaceous plant species will
decrease

3. Abundance
of invertebrates and vertebrates will increase as canopy cover increases due to
the shade (protection from sunlight) provided by the presence of wooded plants.