R. Gr. Stapledon and T. J. Jenkin 41 



V. THE EARLY STAGES IN THE STABILISATION 



OF GRASSLAND. 



These can be accurately studied on fields of which the agricultural 

 history is well known from the first year they are put down to grass 

 until they are 10-20 years old. 



Middleton(ii) has pointed out the gradual stages in the development 

 of a pasture, which passes from youth through middle to old age. It 

 will be shown that youth constitutes the period when the sown species 

 are competing with arable land weeds and the secondary indigenous 

 plants ; middle age when the more persistent sown species are competing 

 with the secondary plants and with the primary species ; and old age 

 when the secondary and primary plants have almost completely domi- 

 nated the herbage. Thus, when old age is reached, a tended pasture 

 has approximated very closely to the semi-natural. 



Thompson (20) has observed that the first year's produce from sown 

 seeds is usually the best, and that after the second year (middle age) 

 there is a marked falling off. On poor soils especially the middle age 

 is the critical time ; and unless the management is good the middle 

 period will commence with the second year; on good soils and under 

 clever management, however, this period can be delayed and rendered 

 less obvious. 



If a field belonging to a well-marked type {e.g. disturbed or undis- 

 turbed heath fescue pasture) is ploughed and but one crop of corn taken 

 and then allowed to run down to grass without seeding it will not imme- 

 diately revert to its original indigenous characteristics. 



For instance on the Cotswolds a field run down from a w^heat stubble 

 in 1908 was observed in 1911 to be still unrepresented by such funda- 

 mental primary species (for that district) as Bromus erectus, Galium 

 verum, and Carduus acaule ; while Carex glauca was considerably below 

 its normal development. In Mid- Wales on the heath types above 

 600' Agrostis vulgaris has on such fields frequently been observed to 

 stand in a higher ratio for at least six years to Festuca ovina than it 

 does on the undisturbed heaths. Thus, when a field is disturbed, to 

 the extent of but one crop, we see that most, but not necessarily all, of 

 the primary indigenous species rapidly re-colonise the ground, but that 

 several years (probably 6-12) must elapse before all the fundamental 

 primary species are again represented and conform to their cardinal 

 figures for the original type. It is, however, when fields have been 

 put through the complete rotation and then sown ^^^th rye grasses 



