Yesterday I spent approximately 8.5 hours collecting 50 replicates. Since my last post my study design has changed dramatically. Instead of investigating the effect distance from the river has on balsam poplar and white spruce seedling density, I will investigate the effect soil moisture has on these densities. I used a soil moisture meter to record soil moisture percentage within each 2 m2 quadrat. I still counted the number of each species within each quadrat to record density. By counting both species within the same quadrat I can ensure that all plants within that quadrat receive relatively the same amount of nutrients (i.e., the same water supply and same sunlight). An added benefit is that this method is more time efficient than counting only one species within a quadrat.
Similar to my last post, the most challenging part of the data collection was navigating to the randomized coordinates. I was surprised by how long it took me to collect all 50 samples. I did consider stopping and continuing the next day, but the forecast predicted rain overnight and this would’ve affected the soil moisture readings. However, as the day went on I had to rely less on the book I was using to identify the two species and this allowed me to speed up my sample time.
I have not yet analyzed my data thoroughly or run a regression analysis. However, it did seem like soil moisture percentage did have different effects on species density. The highest readings consistently had no presence of balsam poplar or white spruce seedlings. Additionally, it seemed the highest densities of balsam poplars occurred at higher soil moisture percentages compared to the highest densities of white spruce seedlings. However, without running a regression analyses I cannot tell if these patterns are true or significant.
Please not this post was updated on April 10th after repeating my data collection using the updated methods.
note*