MIXED CHOP 01' UNIFOEM AGE. 83 



spread the crowns of neighbouring trees, no matter how dense. 

 They thereby not only prevent these latter frojn extending them- 

 selves either upwards or laterally, but reduce the quantity of their 

 foliage, kill and prevent the development ' of twigs and young 

 branches, and induce premature decay and death. They are most 

 destructive, if they are also twiners, 



Qen^r^l Remarks^ 



It will be apparent from the foregoing considerations that a 

 mixed crop which consists of trees of one and the same age, must, 

 in most cases, become gradually either more or less pure, or differ- 

 entiated into groups, each composed more or less exclusively of a 

 single species. This species may be the one most suited to the 

 given soil and locaUty ; but it is not necessarily that one, and, 

 provided that both those main factors of production are sufficient- 

 ly favourable for its prosperous growth, it is essentially that species 

 which is the most tenacious and exclusive of the crop. Its tenacity 

 will depend on its innate vigour up to at least the age of fertility, 

 its accommodating nature in respect of soil and climate, and on one 

 or more of the following properties: — .the resistance it offers to any 

 given cause of injury, (such as, for instance, those described under 

 Conditions III, X and XI), its shade-enduring capacity, greater 

 longevity, the depth to which its roots penetrate, the facility with 

 which it grows up again from the stool and throws up root-suckers, 

 the readiness with which it recovers from wounds and any other 

 kind of mutilation, and its ability to ripen fruit and reproduce itself 

 from seed. Its exclusiveness wiU be due to one or more of the 

 following circumstances : — ^^the special suitability of the soil,, subsoil 

 and locality for its growth, the greater density and more favourable 

 shape of its crown, its capability of pushing up into and through the 

 crowns of other species, its greater rapidity of growth (especially 

 during its youth), its superior stature, the greater facihty with 

 which it shoots up again from the stool and throws up root-suckers, 

 the longer duration of its foliage and the season at which this is 

 shed or renewed, the number of flushes of leaves it brings out in 

 a single growing season, the inva,sive spread of its roots or under- 

 ground stems, the readiness with which it replaces a broken or in- 

 jured leader, early, abundant an,d frequent frueti^cation, the easy 

 dissemination and gennina,tion and great vitahty of its seed, and 

 the season at which tins ripens and is shed.. A species may be 

 tenacious without being exclusive, as B.oswellia serrata, Prosopis 

 spicigera, Acacia Catechu, Hardivickia linata, teak and Finns longi- 



