ly] LANDSCAPES AND VEGETATION 555 



habitats, will give many useful pointers, as it will also in such matters 

 as shelter and water-supply, if these have to be considered. For 

 vegetation is often the best indicator of conditions not only in the 

 air but also below the surface of the ground, landscapes being, as 

 we have repeatedly observed, frequently best interpreted through 

 their ' green mantle '. Moreover, the occurrence of similar groups 

 of plants in different spots usually indicates a close similarity of 

 conditions, while the converse usually holds, at least throughout an 

 area of fairly uniform climate. So, altogether, careful and suitably 

 enlightened observation of vegetation can be of the greatest practical 

 value. 



In these considerations, whether the emphasis is practical or 

 academic, it should be remembered that vegetation may not only 

 accentuate but also mould or even be responsible for some landforms. 

 For plant growth promotes deposition, as of sand on dunes and silt 

 in water, and increases the accumulation on natural levees of material 

 from flooding rivers. Plants also cause the chemical separation of 

 calcium carbonate which is largely responsible for ' coral ' reefs. 

 Moreover vegetation impedes erosion, conserving the soil and 

 underlying mantle of weathered rock or transported material by 

 reducing or preventing removal by wind or water. With its flow 

 thus retarded, rainwater or snow-melt water is permitted to sink 

 into the ground, the vegetation being in turn favoured in what often 

 becomes a mutually cumulative effect. And as the soil and under- 

 lying mantle are protected by vegetation from erosion, so is the 

 bedrock protected from the weathering that precedes erosion 

 (apart, of course, from the small amount of weathering of exposed 

 rock surface that may be caused by plant growth). Thus mav parts 

 of landscapes be moulded ; and hence the wide use of vegetation 

 for wind-breaks, shelter-belts, dune-stabilization, and prevention of 

 erosion by excessive run-off and other means. Vegetation, whether 

 natural or planted, is, or should be, not only the main medium but 

 also a leading tool of the conservationist. 



Land-Use Classification 



For the all-important practice of the most effective land utilization 

 in an area, intimate familiarity is necessary with the vegetation and 

 other local manifestations. In the words of Dr. Edward H. Graham 

 (in his work cited at the end of the present chapter), this should be 



* Not the detailed inspection of the micro-biologist or soil analyst, but 

 a consideration of landscape as an ecological complex prescribing the 



