A study of the effects of canopy coverage on the abundance of herbaceous plant species in Danby Woodlot at York University

Hypothesis Taller plant species with higher canopy coverage outcompete shorter plant species due to interference competition for sunlight. Therefore, in areas with a high canopy coverage, there will be a lower abundance of herbaceous plant species. Predictions: 1. The higher the canopy coverage, the lower the abundance of herbaceous exotic plant species and herbaceous native plant species. 2. The higher the canopy coverage, the lower the ground coverage. Study-Site description Data was collected at the Dandy Woods on York University’s Keele campus. This was a woodlot (forested area), containing primarily deciduous trees, with no water source. The area was rectangular in shape and was approximately 250000m². It was bordered by Chimneystack Road to the north, Keele Street to the east, grassland to the south, and the Chimneystack Lot to the west. GPS coordinates for the woodlot was 43.768756, -79.5079. Elevation for the woodlot was 126.30201 m. The weather was mostly rainy with temperatures reaching 12C and humidity reaching 88% and wind speeds of 23km/h. Meta-Data Data was collected from a woodlot (43.768756, -79.5079) at York University’s Keele campus. Data was collected via visual survey using transects (two 30m transects), pan traps, 1mx1m quadrats, sweep nets and point survey techniques. For the first data set we obtained the abundance of native plants, abundance of exotic plants, and total number of flowers via quadrat sampling (n=25) along a 50m transect (east to west). Every two metres a quadrat was placed on alternating sides of the transect. The number of individuals of herbaceous native and exotic plant species were counted within the quadrat. Grass species were considered to be exotic and all other plants were considered native. Next, the total number of observed flowers within the quadrat were counted; all levels of inflorescence (i.e. buds and blossoming) were considered flowers. For the second dataset a 50m transect was drawn (east to west) and the measured variables were abundance of woody plants, canopy cover, ground cover, and total number of flowers. Abundance of woody plants were counted every 2m within 0.5m of the transect. Only plants larger than 1.5m in height were counted. Having a height requirement decreased the probability of counting a non-woody plant. Also, every two metres, the ground cover and canopy cover was approximated in percent by visually dividing the ground and canopy space into quadrats, then the area covered was estimated by the surveyor as a percentage of the total space. Total number of flowers were counted within 0.5m of the transect on both sides every 2m (n=25). For the third dataset, abundance of vertebrates, diversity of vertebrates, abundance of invertebrates observed and abundance of humans were measured. A 50 m transect was drawn (east to west) and point surveys were conducted via visual inspection of the area within a 50m radius of the start point of the transect. The total number of vertebrates, diversity of vertebrates and abundance of humans was observed for a 15-minute period (n=2). Then in 15 minutes, all humans not part of the study group were counted to survey pedestrian circulation. Following, the abundance of invertebrates was counted (i.e. insects, mollusks, etc.) within a 5.0m radius of the start of the transect for 15 minutes (n=2). For the fourth dataset (measuring abundance of invertebrates in pan traps and abundance of invertebrates caught in sweep nets), 6 pan traps (blue, white, yellow) were placed 3 meters apart along a 50m transect while alternating colors. The pan trap was left for 45 minutes and then the number of invertebrates caught were counted (n=6). Then, along the 50m transect, sweep nets were used to catch any invertebrates (flying and ground-dwelling). The nets were swept upwards from a left to right motion low to the ground (n=10). Methods: 50m transects (combining two 30m transects) were run (east to west) in the woodlot; quadrat samples were taken on both sides of the transect every 2m (n=25). To count the abundance of native and exotic herbaceous plants, surveyors used a 1.00m x 1.00m quadrat to visually inspect and sample individuals. Sampling was conducted by the surveyor counting the abundance of native and exotic herbaceous plants per the bottom-left quarter of the quadrat, the sampling was then multiplied by a factor of 4 to gain total abundance. Total number of flowers were counted and inspected by the surveyor (inflorescences were counted as individual flower units). For woody plants, a 50m transect was run (east to west) and for every 2m a surveyor observed for woody plants (defined as plants with a height greater than or equal to 1.5m) within 0.5m of the transect (n=25). At these points, canopy and ground coverage was estimated via surveyor’s visual inspection, by visualizing quadrats above and below the surveyor. As well, total flower numbers were recorded similarly within the 0.5m area (from the transect) as described above. Point surveys were conducted for periods of 15 minutes (n = 2) for the abundance of vertebrates, diversity of vertebrates, abundance of invertebrates, and abundance of humans. The survey involved running a transect for 50m and a surveyor visually inspecting and counting for the abundance of vertebrates, diversity of vertebrates and abundance of humans within a 50m radius of the transect start point. Diversity of species was determined via visual inspection. Within a 5m radius of the transect start point abundance of invertebrates was measured. Pan traps were set 3m apart while alternating colours (yellow, blue, white) along the length of a transect (50m). Each pan trap was one replicate (n=6) and the total number of invertebrates within the pan trap were counted and recorded. Then, sweep nets were conducted next to the 50m transect. Each sweep was one replicate (n=10) and the total number of invertebrates found at the end of the sweep were counted and recorded. Variable Definitions Abundance of native plants – The visual inspection and count of native plant species (primarily flowering species) per a 1.0m x 1.0m quadrat. Numerical, discrete. Abundance of exotic plants – The visual inspection and count of exotic plant species (primarily grass species) per a 1.0m x 1.0m quadrat. Numerical, discrete. Total number of flowers (quadrat) – The visual inspection and count of flowers (inflorescences were counted as single units) per a 1.0m x 1.0m quadrat. Numerical, discrete. Abundance of woody plants – The visual inspection and count of woody plants (taller than 1.5m). Numerical, discrete. Canopy cover – The visual estimation of the percent area covered by the canopy of the woody plants. Numerical, continuous. Ground cover - The visual estimation of the percent area covered by the herbaceous plants on the ground. Numerical, continuous. Total number of flowers (transect)– The visual inspection and count of flowers within 0.5m of the transect on both sides. Numerical, discrete. Abundance of vertebrates – The visual inspection and count of vertebrate species in the radius of the point survey. Numerical, discrete. Vertebrate species – The visual inspection and count of the diversity of vertebrate species within the radius of the point survey. Numerical, discrete. Abundance of invertebrates – The visual inspection and count of invertebrate species in the radius of the point survey. Numerical, discrete. Abundance of invertebrates pan traps – The visual inspection and count of invertebrates caught in pan traps during a 45 minute period. Numerical, discrete. Abundance of invertebrates sweeps – The visual inspection and count of invertebrates caught in sweep nets over a 50m transect. Numerical, discrete. Habitat – The study site area which includes: forest, grassland, disturbed area, impermeable surface, or near pond. Categorical, nominal.