54 Botany 



on the Boulder Clay, and merit special consideration. They are almost all 

 of the type known as "coppice with standards", in which standard oak 

 trees (Quercus rohur) project from a dense shrub layer consisting mainly of 

 hazel [Corylus avellana), which is coppiced at rather irregular intervals. 

 They were classified by Adamson many years ago as of the (ash)-oak- 

 hazel type, derived by exploitation from the natural woods by suppression 

 of the ash, which, however, by its strong regenerative powers still gives 

 clear evidence of its natural status. AfFmities with the ash woods of 

 calcareous soils are shown by the frequency of calcicole shrubs such as the 

 spindle tree, Euonymus etiropaeus and the wayfaring tree. Viburnum lantana, 

 and by herbs in the undergrowth such as Mercurialis perennis, Viola silvestris, 

 and Hypericum hirsutum. The bush species are numerous and include Acer 

 campestre, the maple, which is often coppiced with the hazel ; both species 

 of hawthorn; the Crataegus monogyna, much less frequent as shrub tmder- 

 growth than C. oxyacanthoides; privet (Ligustrum vulgare) ; dogwood (Cortius 

 sanguinea); and blackthorn [Prumts spiiiosa). The maple, privet and dog- 

 wood are more frequent than in pure Quercetum roburis. Some woods also 

 contain Viburnum opulus, Salix caprea, S. cinerea, Prunus cerasifera and Daphne 

 laureola. 



The early work of Adamson on Gainlingay Wood shows most clearly 

 the dependence of woodland characters upon soil. Most of the wood has 

 a calcareous marl soil where the Boulder Clay overlies Gault, but there is a 

 smaller inland area with a loam soil where the Boulder Clay is above Green- 

 sand. The two regions differed strikingly from one another. Abundant 

 coppiced species on the calcareous clay were the ash, maple and hazel, but 

 these were infrequent on the non-calcareous loam. Conversely, the two 

 birches {Betula aiha and B. pubcsceus) were frequent on the loam but absent 

 from the clay. Similar wide divergences were recognisable between the 

 undergrowth communities. Adamson recognised on the clay soU the four 

 following societies : 



(i) Filipendula uhimria society — high summer water content and low 

 light intensity. 



(2) Filipendula ulmaria-Deschampsia caespitosa society — with high water 

 content but lighter than (i). 



(3 ) Mercurialis perennis society — on drier soils and with a wide light range. 



(4) Fragaria vesca society — in conditions intermediate between those of 

 (2) and (3). 



On the loam soil, he recognised two societies, a Pteridium aquilinum-Holcus 

 mollis society on the heavier loam, and a Holcus mollis society on the sandier 

 loam. 



