Make a copy of this document, fill in your answers during and after your lab in google docs, and then download as a .docx or .pdf file to submit to Canvas by your lab section’s due date. Reading Scientific Literature (Rehling et al. 2021)
1. What two questions were addressed in this research study? (see end of Intro)
● How do species allocate their biomass in response to density and nutrient levels?
● Do species’ functional group, life span, and realized niche with respect to nutrients influence their responses?
2. List three independent variables that were tested in this experiment.
● Seedlings
● Density
● Nutrient levels
3. What dependent variable(s) was/were measured?
● Biomass
● Height
● Length
4. Looking at Figure 1, explain in your own words how plant density affected biomass. How did this differ between individual plant biomass and pot biomass?
● At high nutrient levels and densities, plants produced more total biomass per pot. However, at low nutrient levels, biomass per pot increased more strongly with density. When nutrients were abundant, mean biomass per individual was higher. Density also caused a decrease in mean biomass per individual, but the effect was stronger when nutrients were abundant. Individual biomass of forbs was lowest at all densities, while legume biomass decreased less with density than grass biomass. An interaction between density and nutrients influenced the mortality of individuals in a pot. At low and intermediate plant densities, almost all individuals survived, but many plants died at high densities.
5. Summarize the overall findings of this study in your own words.
● In the analysis of 43 herbaceous plant species, the amount of biomass assigned to roots regularly increased with density, indicating that competition for below-ground resources may be more substantial than previously thought, even at relatively high nutrient levels. This research also shows that plants modify their biomass allocation patterns and the morphology of their roots and stems in response to nutrient availability and density. The functional type, life span, and realized nutritional niche of a plant all influence these reactions.
Hypothesis Testing
Write the responses to these questions using complete sentences and check your spelling and grammar before submission.
1. What is the hypothesis of your plant competition experiment?
2. State your treatment (independent variable) and what the levels are, and the response (or dependent) variables that you will analyze at the end of the experiment.
3. For the response variables, write out your predictions based on your hypothesis.
4. What controlled variables will need to be kept constant for each replicate?
