580 INTRODUCTION TO PLANT GEOGRAPHY 



control, such works as H. H. Bennett's Elements of Soil Conservation, 

 second edition (McGraw-Hill, New York etc., pp. x + 358, 1955) and 

 Paul B. Sears's Deserts on the March, revised edition (Routledge & Kegan 

 Paul, London, pp. xi -[- 181, 1949) are to be recommended as both vivid 

 and readable, while John D. Black's more recent Biological Conservation 

 (Blakiston, New York & Toronto, pp. xiv + 328, 1954) deals with other 

 practical aspects and has a useful annotated bibliography. 



On the subject of indicators, F. E. Clements's Plant Indicators (Carnegie 

 Institution, Washington, D.C., Publication No. 290, pp. xvi + 388, 

 1920) is still the standard work, although an abridged version appears 

 in his Plant Succession and Indicators (Wilson, New York, pp. xvi + 453, 

 1928). Chemical control of plant growth, etc., is dealt with in L. J. 

 Audus's Plant Growth Substances, second edition (Leonard Hill, London, 

 pp. xxii -j- 553, 1959), and applied ecology in H. J. Costing's The Study of 

 Plant Communities, second edition (Freeman, San Francisco, Calif., pp. 

 viii + 440, 1956) 



Additional reading on particular topics has been suggested at the 

 end of almost all previous chapters under the heading of ' Further 

 Consideration '. 



