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.

项目描述：本项目的核心目标是探究红花槭（Acer rubrum，红枫）叶片氮再吸收的种内变异特征。具体而言，我们旨在验证叶片养分再吸收是否与年平均温度、降水量等气候因子存在关联。本研究通过社区科学项目（community science project）收集绿叶与落叶样本，参与者需将叶片寄送至波士顿大学（Boston University）的实验室进行分析。2019年春夏之际，我们联系了美国境内红枫分布区的所有植物与自然爱好者组织，请求其向成员推送本项目信息，号召参与红枫叶片采集工作。感兴趣的参与者需填写包含基础联系方式的谷歌表单（Google Form）。随后，每位参与者会收到一套采样套件（sampling kit），内含手套、采样规程及数据表。从同一棵树采集的每组叶片均被赋予唯一标识“tasper-###”（###为唯一编号），绿叶与落叶的标识编号不同。同一标识（如tasper-120）下的每片叶片会被单独赋予字母a-n编号，其中n代表该树所采集叶片的数量；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。单叶样本通过300 dpi分辨率的平板扫描仪（flatbed scanner）扫描以进行面积分析，并称重。碳氮（C&N）分析时，从同一棵树的绿叶或落叶组中取每片叶片打孔，样本混合后，每棵树的绿叶和落叶分别获得一个碳氮浓度值。打孔样本使用研钵与杵（mortar and pestle）研磨均质成粉末，取约3 mg干燥样本，通过NC2500元素分析仪（CE Elantech，美国新泽西州莱克伍德）测定碳氮浓度。本研究采用美国国家标准与技术研究院（NIST）苹果叶作为标准参考物质。