Final answer:
The lab group could focus their investigation on the effect of overcrowding on deciduous trees, competition on deer population, and disease on the bird population.
Step-by-step explanation:
The focus of the investigation should be on a density-dependent limiting factor. The lab group could use the following questions to guide their investigation:
- What is the effect of overcrowding on the number of deciduous trees? This question focuses on the impact of population density on tree populations.
- What is the effect of competition on the population of deer? This question explores how competition among the deer population affects their numbers.
- What is the effect of disease on the bird population? This question investigates the influence of disease on bird populations in the forest ecosystem.