British Ecology During the Past Quarter-Century: The Plant Community and the Ecosystem

FIRST of all I must express my lively sense of the great honour the Society has done me by electing me to its Presidency for a second time. It is an interesting and on the whole a cheering exercise to look back over the quartercentury that has elapsed since the foundation of the Society, to compare my estimate of the position of British ecology in 1914 with what we may say of it to-day, to contemplate the good work that has been done during the period, and the promise of the future. Nearly all that I said of ecology as a subject in my Presidential Address of May, 1914, on the eve of the Great War, is still, in my judgment, true. The ecological outlook on biology is vitally important, not only to pure science but because of its application to human life and activity in the widest sense. The difficulties of the subject are still very much what they were 25 years ago, and the right ways to overcome them have not changed. In 1914 I looked forward confidently to a development of ecology which would give it a much higher status in the estimation of biologists at large and of those who should be concerned with its practical applications; and this expectation has been to a large extent realized. It is true that progress has been somewhat slower than I anticipated-at least in my more optimistic moments. But what we may call the rise in ecological stock has been fairly proportional to the increase in value and interest of the work produced-and that is as it should be. I think it is still not clearly enough realized, especially by those biologists who are not ecologists, that ecology is not so much a special branch of biologyin the sense that genetics or the physiology of nutrition are special branchesas a way of regarding animal and plant life. Its development depends on the application of various kinds of biological technique, as well as the techniques of physics and chemistry, to the problems presented by animals and plants studied in their natural and semi-natural environments. To these borrowed and adapted techniques are added those of the ecologist's own devising. A large part of the future work of plant ecology will, I think, be concerned with life form and its relation on the one hand to environment and on the other to heredity. Necessarily involved in this work is the whole problem of the phenotypic complexes which we call species and their relation to genetic constitution-a topic recently brought prominently to the attention of the