NOTES AND ABSTRACTS. 
559 
Unless the Government will assist in planting them, one of the greatest natural 
resources of the country must remain undeveloped. 
The benefits of national afforestation may be summarized as follows : — 
1. It would turn many barren wastes into profitable woodlands. 
2. It would retain, in the rural districts, thousands of men who now have to 
seek employment in the towns. 
3. It would keep in this country, for the benefit of the country, millions of 
pounds now paid away to foreigners. 
4. It would enable a large number of small holdings to be established on 
economic lines. 
5. It would lead to the development of many new industries. 
6. It would ensure such a supply of timber as would enable British industries 
to be carried on, without curtailment and without anxiety, in the event of another 
great war. 
From a variety of reasons, conifers have become more and more the principal 
forest trees in temperate climates. As this tendency is likely to increase in 
the immediate future, it is becoming increasingly necessary that the diseases 
of coniferous trees should be understood. The Chermesidae are all enemies of 
coniferous trees, namely, spruce, larch, pine, silver fir, and in America, Douglas 
fir. The damage done by these pests is largely dependent on the vigour of the 
hosts. Thus, when the environment of the conifers is ideal, the damage done by 
the Chermes is not important, but the biological adaptations of the Chermesidae 
are such that the slightest diminution in the health of the trees means that 
these pests become serious enemies. 
The most important matter connected with the rearing of plantations un- 
doubtedly lies in the selection of suitable species for the margins, together with 
their after-management. Unless this important matter is carried out on sound 
principles, it is hopeless to expect any plantation to reach maturity and produce 
the best commercial timber. In fact, the whole life of the plantation, till it 
reaches maturity, may be said to be entirely dependent on the stability of the 
margins* 
A great deal has been written on the varieties of trees which should be grown 
and the best methods of treatment ; but seldom, if ever, has any reference been 
made to the formation and management of margins. Both in theory and in 
practice do we find that margins have been neglected. The trees forming these 
are generally the same species as are found in the interior of the plantation, and, 
what is often worse, the treatment meted out to them is often the reverse of 
what is required to train a substantial wind-screen. 
It is generally found that the practice has been to thin the interior and leave 
the marginal trees close together, especially in exposed situations, in order 
that they may break the blast and give shelter to the interior. Under this 
treatment the trees become drawn-up, tall and slender, the side branches are 
destroyed, the trees become stunted in growth and covered with lichens, there 
is no room for root development, and, instead of forming a barrier to the wind, 
they are themselves laid low. 
The lack of a good margin allows the wind to have full play underneath, 
so that the forest floor is swept clean for a considerable distance, The soil is 
thus robbed of that important part of a forest soil — a humus layer. 
One of the outcomes of the war may be the recognition by the British 
mining industry of the possibility of its demands for pit-props being met by 
the use of home-grown timber. It would therefore appear desirable for producers 
to consider whether they can meet such a demand and the best method of main- 
taining a supply. 
* In the past practically the omy marketable product of British woodlands 
has been mature timber. This means a rotation of at least sixty years, so that 
no individual lives to market the crop he has planted — a fact which has greatly 
retarded afforestation. While mature timber will still be in demand, and in 
all probability maintain its value, it seems quite possible by careful selection 
of site and genus to grow a crop of pit-wood which will give a good return in 
fifteen to eighteen years. The advantage of a short rotation to the grower is 
so obvious that no comment is needed, and its advantage to the nation by 
reducing payments to other countries for foreign wood is equally apparent. 
•-"It is believed that there are at least four different trees which can be grown 
in Britain that will give a crop of pit-wood in fifteen to eighteen years. 
The study of the diseases incidental to coniferous seedlings, while of great 
interest to the plant pathologist, may be of the greatest practical value to the 
nurseryman and forester, especially when not only the cause is ascertained, but 
