DBH of Ulmus Affecting Photo Fall2016


        Photosynthesis is an important process for individual tree longevity and forest ecosystem sustainability. However, little is known about how photosynthesis varies as a function of tree size including diameter. The goal of this research project was to find out if the diameter at breast height (DBH) had a relationship to photosynthetic capabilities in Ulmus ‘Morton Glossy’ trees. The research question was deemed important because of the lack of information currently available for this topic. Plant and tree investigations looking into the photosynthetic capabilities of an organism will not be accurate unless the data include the fluorescence of the leaves, according to Maxwell and Johnson (2000). According to Gitelson et al. (1999), chlorophyll fluorescence was dependent on the pigment content and the absorption of the leaves. According to Jiang et al. (2006), photosynthetic abilities in leaves are the highest once the leaves are fully developed. The data were collected in the first 4 to 5 weeks of the project to ensure that damaged leaves that were dying off were not used as data replicates. The research questions for this project are: does the DBH of Ulmus ‘Morton Glossy’ affect the photosynthetic efficiency of this species? Do the photosynthetic abilities of this species vary based on quadrants orientation in relation to sunlight? 

      It was hypothesized that the larger the DBH of Ulmus ‘Morton Glossy’, the higher the photosynthetic ability because the DBH could be an indicator of how well the tree grows, implying higher photosynthetic functioning. The hypothesis, if supported, would advance the science and management of Ulmus ‘Morton Glossy’ by filling a research gap in this field.   

        This study was conducted on Michigan State University’s campus on five different trees chosen of the same species, Ulmus ‘Morton Glossy’ planted in 2008. In order to collect the photosynthetic efficiency values, an android tablet connected to the PhotosynQ website and the MultispeQ device were used (Kuhlgert et al. 2016). On every data collection day, 120 replicates (i.e., leaves) were taken on each tree. Six leaves were taken from each quadrant of each tree (NW, NE, SW, and SE) and were chosen at random with 1444 data points taken in total.Each leaf from each quadrant was clamped in the MultispeQ device which then transferred the information regarding the photosynthetic efficiency to the PhotosynQ website, which was used to keep track of the data.In order to compare these data to each tree’s DBH values, each tree’s DBH was calculated by measuring the circumference at approximately 1.35 m from the ground. This circumference value was divided by the value of pi to come up with the actual DBH value. An ANOVA test was completed to compare Phi2, PQ SPAD, and LEF in the 4 different quadrants of the 5 trees. Additionally, a correlation test was completed to see a visual representation of the DBH compared to specific photosynthetic capabilities.  

Random sampling Method MultispeQ #19


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


  1. Ulmus 'Morton Glossy' Tree codes? (Multiple Choice)
  2. Quadrant Sampled? (Multiple Choice)
  3. Leaf Number? (Multiple Choice)



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