Plant+Competition+Lab+TA+Manual

**Lab 7: Competition** The purpose of this lab is to observe intraspecific and interspecific competition in two different tree species in Baker Woodlot. In addition, students will learn to use correlation as a method to analyze their data. - Understand the difference between intra- and interspecific competition - Witness competition in the field - Learn about what a correlation is, what a correlation coefficient means, and how to graph variables that are correlated. Meet at the ERCPL parking lot at the beginning of class. Once everyone gets there, walk with the students into Baker Woodlot. We will determine the area where we will sample in the TA meeting, but we should be west of the main path just after you enter through the fence. The equipment box will be hidden in a spot to be determined in lab meeting. Each group needs: Equipment - 1-meter stick - 1 30-m tape - 1 tree-ID book and tree ID packet - 1 DBH tape - compass - 8 flags to mark transect and 6 m sample points Set each group off about 10 meters apart from each other and have them use the random numbers table to find their transect location. Once there, they need to set up a 30m transect going in the east west direction. Each group must then identify the most dominant tree species along their transect (most likely sugar maple or American beech) and label it as species 1. At each 6m interval, find the closest individual of species 1 and record it’s DBH on their data sheet. Then find the next closest individual of spp 1, measure it’s DBH and also record how far apart it is from the original. Using the same original tree, find the closest interspecific neighbor, identify it and measure it’s DBH and the interplant distance from the original tree of spp 1. Record that data in the interspecific pairs table on the bottom of their data sheet. Then move 6 more meters down the transect and repeat these steps until they reach the 30m mark. The tricky thing here is that they record both the intra and interspecific pairs info from the same transect at the same time. This makes the data collection much more efficient. Sometimes you will have them recording the same individual tree from multiple transect positions (especially if there are few trees in their transect area) this situation is fine. Just keep recording data. Once each group finishes collecting data, take your class to the specified rooms in either the Life Sciences Building or Plant Biology.  Once in the room, explain linear correlation and how to calculate it to see if two variables are correlated. Make sure to stress that correlation does not indicate causation. See the example on pg 74. This is a step-by-step example of correlation between dissolved oxygen and macroinvertebrate species diversity. Also, please explain the difference between r and R2, as students easily get these concepts confused. Have each group calculate the mean, standard deviation and correlation coefficient between the sum of the pair sizes (y-axis) and the interplant distance (x axis). Then, they need to graph their results. There will be 2 separate graphs, one for intra and one for interspecific competition. Each graph needs to be properly labeled and should be accompanied by a summary of their findings. Discuss as a class the different findings of each group. How do we know if there is competition? What types of resources are the trees competing for? If we detect competition, what trend should we expect in our data and why? Each group turns in one copy of both graphs and their calculations before the end of class. -- Grading: 3 points for intra graph including properly labeled axes, correlation value, and adequate conclusion statement 3 points for inter graph including properly labeled axes, correlation value and adequate conclusion statement 3 points for calculations 1 point for overall quality of work -
 * Objectives:**