Final answer:
Quadrat sampling is best suited for immobile organisms like plants, making it the preferred method for estimating the population density of Ponderosa pines.
Step-by-step explanation:
When it comes to estimating the population density of various organisms, scientists employ different methods tailored to the characteristics of the targeted species. For immobile organisms such as plants, a method known as a quadrat is typically used.
This involves placing a square structure randomly on the ground within the habitat and counting the number of individuals that fall within its boundaries. Ponderosa pines, being immobile organisms, are ideal candidates for this approach. As trees, they are stationary and easily counted within the defined quadrat area, making this method both practical and reliable for assessing their population density.