Danby Grassland Aster Transect Dataset

Site DescriptionSampling taken outdoors in the Danby grassland on the York University Keele campus. The weather was a mix of sun and clouds, 28 degrees Celsius. The grassland was a clearing with no tree canopy, and surrounded by trees and a woodlot on all sides. Samples were taken from 2:30-5:00 in the afternoon. There was continuous ground cover at the site. Metadata Height: The first factor is height. The height of each plant was measured in centimeters using a measuring tape. The plant was measured from the base of the stem to the top of the stem. If the plant was bending over at all, the stem was pulled straight and taught alongside the vertical measuring tape. No broken-stemmed plants were included in the data. Level of Crowding: The second factor is level of crowding. Crowding was measured on a scale from 0-3, based on the following definitions: 0 = open, 1 = some plants nearby, 2 = quite a few plants nearby, and 3 = very crowded bunch of plants, all within 50cm of the plant of interest. Number of leaves: The number of leaves is the response. We counted all the leaves on every stem of the plant (including if the stem branched into 2 or more separate stems), including both dead and living leaves. Size was not relevant when counting. We included broken/partial leaves as well in our count. Methods A 30-metre transect was placed randomly in the Danby grassland, and was extended on a straight path to a length of 25 metres. I then walked along the transect, beginning at 0m. Each time an individual of the plant species I was sampling was spotted, I stopped and took measurements. 20 plants in total were measured using random sampling. The plant species was identified based on its purple flowers, as well as its leaf shape and characteristics, having one very defined midrib and pointed apex, for plants that had no flowers. Individual plants were determined by observing that each plant had one steam directed into the ground, so even if a plant had multiple stems branching off of the stem going into the ground, all of the branching stems were considered one plant. Hypothesis The height and level of crowding of a plant affect the number of leaves it has. This is because the leaves grow evenly from all parts of the stem, starting just above its base, so leaf number and plant height correlate, and because the level of crowding determines the amount of competition the plant has for nutrients, water and sunlight, which affects the number of leaves it is able to grow. Predictions The taller the plant, the more number of leaves it will have. The higher the level of crowding, the less number of leaves the plant will have.

场地概况
本次采样于约克大学基尔校区的丹比草地户外区域开展。当日天气为晴阴相间，气温28摄氏度。该草地为无林冠的开阔空地，四周均被树木与林地环绕。采样时段为当日下午2:30至5:00，采样区域存在连续地表覆盖物。

元数据
1. 株高：首个测量指标为株高。使用卷尺以厘米为单位测量每株植物的株高，测量起点为茎基部至茎顶端。若植株存在倒伏情况，则将茎秆拉直并紧贴垂直放置的卷尺进行测量。数据中不包含茎秆受损的植株。
2. 拥挤度等级：第二个测量指标为拥挤度等级。拥挤度按照0-3的分级标准进行评定，具体定义如下：0级为开阔无遮挡；1级为周边存在少量植株；2级为周边存在相当数量的植株；3级为目标植株周边50厘米范围内植株极为密集。
3. 叶片数量：本研究的响应变量为叶片数量。需统计植株每一条茎秆上的所有叶片（包括茎秆分叉为2条及以上分支的情况），涵盖存活与枯死的叶片；统计时不考虑叶片大小，破损/残缺叶片亦纳入计数范围。

采样方法
在丹比草地随机设置一条30米样带，并沿直线延伸至25米长度。随后从样带起点（0米处）开始沿样带行进，每发现一株目标采样植物即停下进行测量。本次研究共通过随机抽样法测量了20株植物。目标植物物种通过其紫色花朵、叶片形态及特征进行识别：对于未开花的植株，则依据其具有清晰明显的中脉与尖锐叶尖的特征进行鉴定。植株个体的判定标准为：每株植物拥有一条伸入地下的主茎，因此即便某植株存在多条分支茎秆，所有分支茎秆均视为同一植株个体。

研究假设
植株的株高与拥挤程度会对其叶片数量产生影响。原因在于，叶片从茎基部上方的位置开始沿茎秆均匀生长，因此叶片数量与株高存在相关性；同时，拥挤程度决定了植株在养分、水分与光照方面的竞争强度，进而影响其可生长的叶片数量。

研究预测
植株越高，其叶片数量越多；植株所处环境的拥挤程度越高，其叶片数量越少。