BIOL 2050 - Lab 3: Sweep nets and transect tape

The objective was to use a distance based sampling method to determine the abundance and richness of insects inhabiting a given area. Using a combination of the sweep net method and transect method we were able to actively collect walking and flying insects. The dataset for this experiment was collected on Thursday, October 1 2015 between 3 and 4:00 pm within the grasslands of York University's Keele Campus. This region is isolated from human acitivity. The weather was sunny with a temperature of 15 degrees celsius. The direct sunlight allowed for clear visualization of organisms captured by the sweep net. The materials included in the study were: a stop watch to record time, notebook and pen to record data, transect tape for distance measurement and sweep net for gathering insects. The approach taken was carefully selected prior to the execution of this method. The grasslands were divided into 2 regions, mowed and non-mowed. This study had a total of 10 trials (n=10), 5 trials involved the mowed land and 5 trials involved the non-mowed land. This study involved the participation of all 4 group members (Adilah Ismail, Amrutha Balamurugan, Harshvir Hehar and Olivia Kazmierczak). Harshvir Hehar was responsible for laying out the transect tape to a distance of 20 m. All 10 placements of the transect tape were made cautiously to prevent abstraction of organisms from the same region. Adilah Ismail was responsible for gathering the insects using a sweep net. The sweep net was forcefully moved back and forth in a figure eight motion to extract as many insects as possible. The sweeping motion was kept consistent amongst both the mowed and non-mowed regions. High rising plants were not given any mercy. After sweeping, the net was flipped over so that the open portion of the net was facing the sky and then it was closed off using Adilah's hand to prevent insects from escaping. At this point the abundance and RTUs were counted. Amrutha Balamurugan recorded the time with a stopwatch. The time spent sampling was slightly different for each replicate (with an average time of 23.6 seconds). Olivia Kazmierczak recorded all the data in her notebook. After each trial all organisms captured were released to prevent recounting and restore them into their natural habitat. Overall this sampling method was slightly destructive. There were high concerns of reducing population. It did however, reveal a correlation between the region (mowed vs non-mowed) and abundance of a certain species.本研究旨在采用基于距离的采样方法，测定指定区域内栖息昆虫的种群丰度与物种丰富度。研究结合扫网法（sweep net method）与样带法（transect method），主动采集步行及飞行昆虫个体。 本实验的数据集采集于2015年10月1日（星期四）下午3时至4时，采集地点为约克大学（York University）基尔校区（Keele Campus）的草原区域，该区域与人类活动区域相互隔离。当日天气晴朗，气温为15摄氏度，直射阳光便于清晰观察扫网捕获的昆虫个体。 本研究使用的实验器材包括：用于记录采样时长的秒表、用于记录实验数据的笔记本与钢笔、用于距离测量的样带卷尺，以及用于采集昆虫的扫网。 本研究的采样方案在实施前经过精心论证。研究人员将实验草原划分为两个区域：刈割区与未刈割区。本研究共开展10组重复试验（n=10），其中5组在刈割区域进行，剩余5组在未刈割区域开展。 本研究共有4名小组成员参与（Adilah Ismail、Amrutha Balamurugan、Harshvir Hehar与Olivia Kazmierczak），具体分工如下：Harshvir Hehar负责铺设20米长的样带卷尺；所有10个样带布设点位均经过谨慎选取，避免对同一区域的昆虫个体进行重复采样。Adilah Ismail负责使用扫网采集昆虫，通过以“8”字形轨迹前后强力挥动扫网，尽可能多地采集昆虫；且在刈割区与未刈割区均保持一致的扫网挥动节奏，未对高大植株进行避让。扫网采样完成后，将网口翻转朝向天空，再用手封住网口以防止昆虫逃逸，随后统计捕获昆虫的丰度及可识别分类单元（Recognizable Taxonomic Units，RTUs）数量。Amrutha Balamurugan负责用秒表记录采样时长，每组重复试验的采样时长略有差异，平均时长为23.6秒。Olivia Kazmierczak负责将所有实验数据记录至笔记本中。 每组试验结束后，研究人员将捕获的所有昆虫个体全部释放，避免重复计数并使其回归自然栖息地。总体而言，该采样方法具有一定破坏性，研究人员对昆虫种群数量可能受到负面影响存在较高担忧；但该方法确实揭示了区域类型（刈割区vs未刈割区）与特定昆虫物种丰度之间的相关性。