Macroscale Variation in Red Maple (Acer rubrum) Foliar Carbon, Nitrogen, and Nitrogen Resorption

Project Description The primary goal of this project was to investigate intraspecific variation of foliar nitrogen resorption for Acer rubrum (red maple). In particular, we are interested in examining whether foliar nutrient resorption is related to climatic factors such as mean annual temperature and/or precipitation. The approach used to collect green and fallen leaf samples was through a community science project where participants sent leaves to our lab at Boston University for analysis. In the spring/summer of 2019 plant and naturalist organizations throughout the range of red maple in the United States were contacted to request information about this project be sent to their members regarding the collection of red maple leaves for the study. Interested parties were prompted to complete a google form that included basic contact information. Each participant was then sent a sampling kit which included gloves, sampling protocols, and data sheets. For each set of leaves collected from a single tree they were assigned the following identification “tasper-###” where the numbers were uniquely assigned. Green and fallen leaves were assigned different “tasper-###” numbers. Within a single identification (e.g., tasper-120) each leaf was individually assigned a letter a-n, where n corresponds to the letter of how many leaves were sent from that tree. For most samples a-j was obtained because we asked participants to collect 10 leaves. Individual leaves were scanned for area analysis using a flatbed scanner at 300 dpi and weighed. For C&N analysis each leaf blade from a set of green or fallen leaves from a single tree was hole-punched and the samples were combined yielding one C and N concentration per tree for both each green and fallen leaves. Punches were ground and homogenized to a powder using a mortar and pestle. Approximately 3 mg of dried sample was analyzed for C and N concentration using a NC2500 elemental analyzer (CE Elantech, Lakewood, NJ, USA). NIST Apple Leaves were used as standard reference material.

项目简介 本项目的核心目标为探究红花槭（Acer rubrum, red maple）的叶氮回收种内变异，重点考察叶片养分回收是否与年平均气温、降水等气候因子存在关联。本研究通过社区科学项目采集新鲜叶片与凋落叶样本，参与者需将叶片寄送至波士顿大学实验室供后续分析。2019年春夏季节，研究团队联系了美国境内红花槭分布范围内的各类植物与自然爱好者组织，将本项目的叶片征集信息传递给其成员。有意愿参与的人员需填写包含基本联系信息的谷歌表单。随后，每位参与者将收到采样套件，内含手套、采样规程与数据表。针对单棵树木采集的叶片样本，将被赋予格式为"tasper-###"的唯一标识，其中###为专属编号，且新鲜叶片与凋落叶将使用不同的"tasper-###"标识。在同一标识（如tasper-120）下，每片叶片将被分配a-n的字母编号，n与该树木寄送的叶片总数对应；由于要求参与者采集10片叶片，多数样本的编号范围为a-j。单叶样本将通过平板扫描仪以300dpi分辨率扫描，用于面积分析并称重。在碳氮分析环节，研究人员将从单棵树木的新鲜叶片组或凋落叶组的每片叶瓣打孔取样，将同组样本混合，从而得到单棵树木新鲜叶片与凋落叶各自的碳氮浓度。打孔样品经研钵和研杵研磨均质为粉末后，称取约3mg干燥样品，使用NC2500元素分析仪（CE Elantech，美国新泽西州莱克伍德）开展碳氮浓度分析，实验采用NIST苹果叶作为标准参考物质。