Boreal Ecology Article Review: "Testing hypotheses of trophic level interactions: a boreal forest ecosystem"

This is a review for the article: "Testing hypotheses of trophic level interactions: a boreal forest ecosystem".

A. R. E. Sinclair is associated with the Centre for Biodiversity Research in University of British Columbia, Vancouver, Canada.

This paper describes an experiment done in boreal forest ecosystem at Kluane, Yukon, for a period of approximately 10 years, to determine whether the trophic level interaction follows the bottom-up hypothesis or the top-down hypothesis. Two types of experiments were done to test the hypotheses – addition and removal experiments – where they tested the direct and indirect effects of adding certain factors (fertilizer, hare food) and effects of removing certain factors (predator, hare, vegetation), and effects of adding and removing simultaneously to test the double effects. The results indicated that top-down hypothesis had a stronger direct effect on the trophic level interaction where predators of higher trophic level controlled the quantity of their prey.

The major strength of this paper is its thorough experimentation, where they analyzed many different crucial aspects of direct and indirect effects, as well as the double effects of addition and removal of factors – which requires a high level of knowledge and a broad range of view, which they used to form logical conclusions. The weakness of this paper is in the procedures – if there was any level of wind, it may have moved the fertilizers during the air-distribution if they were not extremely careful; another weakness is that the length of this experiment was not long enough to observe the full extent of the indirect effects. Regardless, the experiment has taken a step from looking at the hypotheses at a theory level to the actual real-life view.

This paper fits well with the course context since it analyzes the interaction between trophic levels in the boreal forest specifically (since the top-down hypotheses may not apply to other episodes). This reading helped understand the direct and indirect significance of predator-prey interactions in the boreal forest and both bottom-up and top-down hypotheses, and what must happen in order to make the hypothesis true.

Source Cited:

 “Testing hypotheses of trophic level interactions: a boreal forest ecosystem,” A. R. E. Sinclair, et al, 89:313-328, 2000.