From the text...'In this Alaskan reconnaissance, I believe we were the first workers to point out that the caribou was a creature of climax vegetation-the lichen tundra-and the moose one of mid-successional vegetation. We became aware of the liberation of the shrub growth of Vaccinium, Ledum, Empetrum, Betula, Salix and Cassiope when the climax blanket of lichen was destroyed. Here was the key to the decline of the caribou and the increase and extension in range of the moose. It was also one of the reasons for the great reindeer crash. Wolves, poachers and what not, that had been given as primary reasons, were actually of little consequence. As I say, we did nothing but use our eyes and our legs, and I would hold that development of the power making comparative observations needs special care in teaching ecology, for we are dealing with long periods of time.....The policy of unquestioning change of natural habitats and communities usually means simplification of the flora and fauna to so-called economic crops of plants and animals; and as far as plants are concerned, a setting back of succession from climax conditions to those of an early stage of succession where annual or shallow-rooted plants are grown. In ecological terms, this simplification or impoverishment of variety is destroying the developed niche-structure of the original community which had resulted in the most efficient turnover of energy within that particular system. Each species is concerned with the conversion of matter, and in terms of Lotka's axiom the collective activities and effects of organisms indicate a direction of organic evolution towards maximum energy intake from the sun and maximum outgoing of free enrgy by dissipative processes in living and decaying dead organisms. In short, there are evolutionary tendencies towards a higher metabolic rate of the ecosystem; maintenance of energy flux is conservation; reduction of it is the opposite of conservation. Knowledge of energy flow in conversion cycles of matter is the stuff of ecology. The Eltonian foodchain is but one segment of the cycle of energy flow. Change in the metabolic pattern of natural communities towards economic ends should be preceded by ecological survey and assessment. The simplification of a highly productive English farm from the climax state of oak woodland has taken place in a specially favourable environment and is sustained in its high productivity by capital, skill and hard work. But to simplify without the capacity to inject one or all of these brings about deterioration, whether it be a Scottish hill sheep farm or an African cattle ranch.'