Investigation of the influence of tree size and tree condition on insect abundance of maple trees in Danby Woodlot, York University

This study was done in collaboration with 3 other team members consisting of Muhammad Akram, Daniel Germani, and Markian Plawiuk.

The purpose of this study was to collect data in order to investigate the influence of tree size and tree condition of maple trees on the abundance of insects within close proximity to the tree. It was hypothesized that there would be a greater abundance of insects if trees were dead and/or large, compared to trees that were alive and/or small. It was predicted that the abundance of insects found in proximity of the trees in predicted in descending order would be: dead and large trees (greatest abundance of insects), dead and small trees, alive and large trees, alive and small trees (least abundance of insects).

The experiment took place at the Danby Woodlot at York University Keele campus in Toronto, Ontario, Canada. The Danby Woodlot consisted of an abundance of different species of trees of various heights and canopy coverage. Overall, there were moderate amounts of canopy coverage within the entire Woodlot, as moderate amounts of sunlight were able to pass through. The Woodlot also had a moderate amount of leaves on the ground, as the study took place in the early Fall season. Data collection was completed on two separate days, each day 1 week apart from each other. The first day of study was Tuesday October 13th 2015, which was a cool and slightly windy, cloudy day with a temperature of 15°C and a wind current of approximately 10km/h. On this day, data collection began at 2:57PM and concluded at 5:05PM. The second day of study was Tuesday October 20th 2015, which was a cool and gloomy day with light drizzles and a temperature of 17°C and a wind current of approximately 11km/h. On this day, data collection began at 2:47PM and concluded at 4:53PM.

Over the two days of data collection, 25 maple trees from each category were studied: alive and small, alive and large, dead and small, dead and large. To locate the next tree to investigate, the members of the group continually walked East further into the Woodlot after sampling the first maple tree found at the centre of the Woodlot. The size of the tree was determined by measuring the dbh using a measuring tape. The number of insects within a 1m2 quadrat placed 1 metre to the left/West of the tree of interest was counted by all four members of the group collaboratively (with each member responsible for 1 side of the quadrat) while using a digital stopwatch to ensure that the duration of counting was consistently 60 seconds for each tree under investigation. On the first day of data collection, 10 maple trees belonging to each of the four categories were studied, while 15 maple trees of each category were studied for the second day of data collection. In total, 100 maple trees were sampled.

Due to the precipitation occurring on the second day of data collection, it was believed that the data collected may have been affected. This was due to how the abundance of insects was likely to be affected by the uncontrollable weather conditions which differed from the first day of data collection.

本研究与另外三名团队成员协作完成，三名成员分别为Muhammad Akram、Daniel Germani与Markian Plawiuk。

本研究旨在通过数据采集，探究枫树的树体尺寸与健康状况对其周边区域昆虫丰度的影响。研究假设：相较于存活且矮小的枫树，死亡或高大的枫树周边昆虫丰度更高。研究进一步做出如下预测：按昆虫丰度从高到低排序，四类枫树的昆虫丰度依次为：死亡高大型（昆虫丰度最高）、死亡矮小型、存活高大型、存活矮小型（昆虫丰度最低）。

本实验开展于加拿大安大略省多伦多市约克大学基尔校区的丹比林地（Danby Woodlot）。该林地内分布有大量不同树种，株高与冠幅各异，整体冠层覆盖率处于中等水平，可让适量阳光穿透；研究开展于初秋时节，林地地表落叶量适中。数据采集分两日进行，两日间隔一周。首次数据采集日期为2015年10月13日（星期二），当日天气凉爽、微风云蔽，气温15℃，风速约10km/h，数据采集时段为14:57至17:05。第二次数据采集日期为2015年10月20日（星期二），当日天气阴冷多云，伴有零星小雨，气温17℃，风速约11km/h，数据采集时段为14:47至16:53。

两日数据采集期间，我们对四类枫树各25株开展研究，四类分别为：存活矮小型、存活高大型、死亡矮小型、死亡高大型。以林地中心的第一株枫树为采样起点，完成采样后研究团队持续向东行进，以此定位后续待研究的枫树。树体尺寸通过皮尺测量胸径（dbh）确定。研究团队四名成员协同计数目标树西侧1米处、1平方米样方（quadrat）内的昆虫数量，每名成员负责样方的一个侧边，并使用电子秒表确保每株待测树的计数时长统一为60秒。首次数据采集日，四类枫树各采样10株；第二次数据采集日，四类枫树各采样15株。本次研究总计采样枫树100株。

由于第二次数据采集当日出现降水，研究团队认为采集到的数据可能受到影响。这是因为不可控的天气条件与首日存在显著差异，而昆虫丰度极易受此类天气因素干扰。