Ace of Acers: DBH Effect on Chlorophyll Content 10Fall2016

Overview

Does bigger always mean better? Chlorophyll is an essential component of photosynthesis and thus influences the very foundation of life. Understanding how chlorophyll varies among tree species based on phenotypic factors is important in assessing the complexities and functions of some of the producers who provide this foundation. It is compelling to study and understand how the size of a tree's diameter at breast height (DBH) affects chlorophyll content. According to Buttery and Buzzell (1977), there is a direct causative relationship between chlorophyll content and rate of CO2 assimilation, meaning that under field conditions chlorophyll content limits photosynthesis. As no current researchers are studying the specific question, the group had to look at similar experiments to help understand the general questions surrounding chlorophyll content. An example of a similar experiment was performed testing chlorophyll content of the leaves of sugar maple as was described by Berg et al. (2004). The research question was: how does DBH of the trunks of Acer rubrum affect the chlorophyll content between the months of September-November?

The research hypothesis for this experiment was that trees that have a higher DBH will better conduct photosynthesis and have higher levels of chlorophyll content. Knowing whether or not DBH affects the chlorophyll content of Acer rubrum can enable other researchers to use the information to see if this relationship changes for different species of trees. Then researchers could pinpoint a relative DBH that corresponds to a specific level of chlorophyll content per tree, so instead of collecting data regularly for specific trees, the tree’s DBH could be analyzed to get a relative idea of its structural components.

To determine if DBH affected chlorophyll content in *Acer rubrum *trees, the response variable of chlorophyll content was measured in the leaves of six different Acer rubrum individuals from September to November of 2016. A data collection process was derived and employed to accomplish this task. The only materials used for the data collection were a stepping stool to reach the leaves and multispeQ device in which data such as chlorophyll content could then be uploaded onto photosynq.org for further evaluation. According to Kuhlgert et al. (2016), the multispeQ device is a cutting edge device capable of collecting high quality field data on a large scale. Leaves were selected arbitrarily from the lower portion of the canopies in four different quadrants; north, east, south, and west. Five samples were taken from each quadrant of the tree thus, 20 samples from each tree and 120 samples in total for all of the six trees for a given day data collection. Group members collected data when it best suited their schedule. Each group member collected 360 samples for a total of total of 1,440 samples (240 from each tree) for the entire experiment. The samples were analyzed first by completing an ANOVA test for the quadrants of each tree to see if any quadrants were significantly different. Once the significantly different quadrants were discarded (i.e., outlier or two lowermost quadrants), a correlation was ran between the DBH of each tree and the mean of the chlorophyll content of each tree.

Works Cited

Berg, A., & Perkins, T. (2004, February 22). Evaluation of a portable chlorophyll meter to estimate chlorophyll and nitrogen contents in sugar maple (Acer saccharum Marsh.) leaves. Forest Ecology and Management, 200(1-3), 113-117.

Buttery, B. R., & Buzzell, R. I. (1977). The relationship between chlorophyll content and rate of photosynthesis in soybeans. Canadian Journal of Plant Science, 57(1), 1-5.

Kuhlgert, S., Austic, G., Zegarac, R., Osei-Bonsu, I., Hoh, D., Chilvers, M., Roth, M., Bi, K., TerAvrst, D., Weebadde, P., Kramer, D. (2016). MultispeQ Beta: A tool for large-scale plant phenotyping connected to the open PhotosynQ network. Royal Society Open Science, 3(10), 160592.

Protocols

Leaf Photosynthesis - MultispeQ Beta ONLY

Measures photosynthesis-related parameters in <15 seconds, including: Phi2, PhiNPQ, PhiNO, NPQt, qL, LEF, and SPAD. In addition, measures PAR (photosynthetically active radiation), ambient temperature and relative humidity.

Works with the MultispeQ Beta device only

Questions

  1. Which quadrant sampled? (Multiple Choice)
  2. Leaf color was? (Multiple Choice)
  3. Acer rubrum tree code was? (Multiple Choice)

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