Modern Geography

by Marion I. Newbigin

We have now taken a general survey of the earth’s surface, have noted its mountain heights and its ocean depths, watched the formation of hills and valleys which is due to the joint action of atmospheric agents, running water and ice, and considered briefly some of the points of interest about climate. We next pass to that most characteristic feature of the surface, its clothing of plants. Except where the surface of the ground has been artificially sterilised by man, or is rendered unproductive by ice, by lava, by a total lack of water, or by the existence of poisonous salts, it is clothed with vegetation, and it is the presence of this vegetation which is its most obvious character.

Here, however, as in other regions of thought, the geographical standpoint has only been reached slowly. Man’s habit of analysis made him study grasses and trees for long generations before he got back to the forest and to the grassland as they occur in nature. Plants as individuals are the province of the botanist, but those plant groups which are the expression of the interaction of climatic factors, soil, and surface relief, are the concern of the geographer.

When we take a general survey of the face of the earth from the point of view of plant geography, we note three main conditions. In certain regions, alike in the tropics and in temperate zones, we find that plants reach their maximum size, combined with great differentiation of structure, and the formation of woody stems which offer great resistance to varying conditions of climate and weather. Such highly-organised plants form forests, which still dominate over a large part of the earth’s surface.

Man’s nearest allies, the anthropoid apes and the monkeys, are for the most part forest animals, and the lowest races of men are still forest dwellers. Where man is a forest dweller he seems not to reach his full size, as we see in the case of the pigmies of the Congo forest, and the negritos of the Philippines, and he suffers from a chronic insufficiency of food, which acts as a check both to his mental and physical development. There has, therefore, always been war between evolving man and the giants of the plant world, a war which has swept the forests away from many of the more civilised parts of the globe, and which still continues, though man’s victory is now so complete that he can afford to be generous, and give protection to the remnants of his former foe.

But over parts of the globe the climate, and especially the amount or distribution of the rainfall, makes it difficult or impossible for forests to grow naturally. Here other types of plants, lower in stature, and evading rather than facing the problems of winter cold or summer drought, flourish and form what we call the grasslands. The grasslands favour man in several respects. They feed the animals upon which he depends for food, for clothing, and for the conveyance of his person or property, and they offer much less resistance than the forest to his agricultural operations. Even the large herbivorous mammals which in their wild state haunt the forests, usually leave these at night to feed upon the grasslands, so that it is the grasslands which have largely fed man at every stage of civilisation. The atmospheric conditions within the woodlands also, the deficient sunlight, the humidity, and so forth, seem unfavourable to human development.

Where the conditions are especially unfavourable to plant life, we find that even the grassland plants are unable to keep up the struggle, and diminish in number, losing their power of forming a complete covering for the soil, and thus the grassland passes into desert, whether the hot waterless desert of low latitudes, or the cold frozen desert of northern ones.

In the most general sense, then, we may say that these three formations, woodland, grassland and desert, divide the surface of the land among them, and between them there is constant conflict. The grasslands are for ever attempting to encroach upon the woodlands, and in this attempt they have been assisted, sometimes to too great an extent, by the operations of man. Similarly the desert is always striving to encroach upon the grassland, and in this endeavour it has been sometimes involuntarily aided by man, who has also done much voluntarily to reclaim the desert land for the grasses.

Let us note next the particular conditions which favour woodland, grassland and desert respectively. The distribution of plants over the surface of the earth at large is determined by a number of factors, by the amount of heat, by the amount and distribution of precipitation, by the nature and strength of the winds, by the characters of the soil, and so on. But forests occur under the equator and also far to the north; we have cold deserts as well as hot ones; there are extensive grasslands in the Sudan as well as in the Canadian Far West. This proves that the varying amounts of heat may be neglected in considering the cause of the distribution of the three great plant formations.

Again, the soil is of minor importance, for different types of forest and of grassland occur on different types of soils. We are thus led to the conclusion that it is the precipitation and the wind which determine the distribution. To understand the reason for this we must consider the needs of different types of plants in the matter of water.