Oaks trees in California produce annual crops of seeds acorn

Oaks trees in California produce annual crops of seeds (“acorns”) that vary dramatically in size fromyear to year. In some years, nearly all of the oak trees produce few if any acorns, and the treesinstead save up their resources. In other years, all the trees in a large area (often nearly the wholestate) synchronously produce a huge crop of acorns (“mast years”). Draw a graph showing the relationship between acorn density and the proportion of acorns likelyto be eaten by herbivores. Explain briefly the key features of the relationship that you plot. Variation in the proportion of acorns eaten across years is an example of what kind of feedback ( negative or postive) explain why.

Solution

Acorns are good source of starch and fat. So, if their density is high, the likelihood of thier being eaten by herbivores is also high. If we draw a graph keeping the density of acorns on the X-axis and the proportion of   acorns likelyto be eaten by herbivores will be rising. However, some animals like squirrels and Jays help in the dispersal of seeds of oak trees when they eat acorn, while other animals do not help in the dispersal of seeds. In this case the production, of acorns is also going to increase. Since, eating of acorns do not decrease their production, instead the dipersal of seeds will increase the production of acorns, this type of feedback is a positive feedback. The graph would look like this-It will be rising line, not fully straight but a little proved.(faced problem while uploading an image from excel of hard drive).