The Study of Plant Life by M. C. Stopes (best ebook reader for laptop TXT) 📕

plants, you will find that, as a rule, in each there is one important plant which grows in great numbers, while there are many more scattered and less important species growing with it. Such patches of plants growing together may be called Associations, and in mapping we only pay attention to the chief of these. In a patch where cotton-grass is the most conspicuous thing, there may be also half a dozen small grasses and plants growing with it, in which case everything but the cotton grass would be ignored in the mapping, and the association called the “cotton grass” association. Similarly, a patch where heather is the most important plant would be called the heather association. Sometimes you may find two or more plants growing together which seem to share the area between them, so that it is impossible to tell which is the chief one; in such a case where, for example, heather and bilberry are apparently equally important, the association would be described as “heather-bilberry.” For the sake of reference, lists should be kept of all the plants of less importance growing in the associations, though they are ignored in the mapping.

At the beginning it is wise to go over the area and find out roughly how many chief associations there are in it, and to make out a list of them. Then choose either a colour or a sign to represent each of them in the mapping,—a colour will generally be found to be clearer and more effective in the finished map, though a sign is very useful for the field-work.

When all these preliminaries are finished, begin the actual mapping by going very carefully over the different patches in the staked-out area of one piece of the sheet. From the details already printed in the ordnance survey map, you will generally be able to find the exact position of the patches of plant associations (unless they are very small, when they must be ignored), and you should soon be able from the help of the given details to fill in the shape of the patches by the eye. If in any case this is difficult, a 5-foot rule and a string of 20 feet or 30 feet marked out into 5 feet and 1 foot lengths will be found very useful. From the actual measurements you will then get, it is easy to find how much will represent them on the map by the simple sum:—1,760 actual yards are represented by 25 inches on the map, so that 16, 10, or whatever number of feet you require will be represented by (25 in. x 10 in.)/(1,760 x 3) or (25 in. x 16 in.)/(1,760 x 3) and so on.

Do all your field-work in pencil, and take notes in a “field-book” as you go, so that you will be able to copy out a neat, correct map at home in which to colour in the associations and outline the patches with waterproof ink. When one of the sheets is done in this way, stake out the area for the next, and so on, till you have all the sheets finished. Then paste them together again on a piece of muslin in their proper order, and you will have a complete “plant-map” of one definite, though small, area. This can be easily compared with a geological map of the same area, though the geological one will be on a rather smaller scale (best 6 inches to the mile), and you will see how the patches of plants frequently follow the arrangement of the rocks. This does not show so clearly on too small an area; the larger the district you can cover the better.

To work from an ordnance survey map is the easiest way of proceeding, but if you like to combine the plant study with a little simple survey work, it is quite possible to make the map from the very beginning. This is not generally worth the trouble, except in cases where you find a rich and interesting area which would repay very careful mapping on a larger scale than the survey have published. For example, it would be a very good plan to choose some small area, and in it stake out exactly 100 feet square. Along the sides plant smaller stakes every 20 feet, and map all the details very carefully on to mathematical paper on the scale of either 5 inches or better, 10 inches to 100 feet. Such an area would well repay the trouble of repeated mapping at different times of the year. If you have a series of maps of the exact area every two months, for example, you will be able to see from them very well the succession of plants throughout the year, and how the associations change according to the seasons.

Another thing that should go with the mapping is the plotting out of “sections” through the irregular land, which will show clearly how frequently the plants growing on any spot are determined by the level of the spot and its consequent relation to the water supply. The most striking case of this kind is that of a section through a pond or stream and its banks. Unless you have a boat at your service, you will have to choose a stream where two people can meet across it from the banks, or else content yourself with going out only as far as you can wade.

To begin the “section” you should choose a good place where there seems to be plenty of variety in the plants; then fix a strong stake into the water as far out as you intend to go, tying on to it a string measured out into 1-foot divisions. This string should be 20, 30, or more feet long, according to the kind of edge the pond has, and its other end should be fastened to a stake also.