Welsh Journals

such as Alder which does not have its growth limited by the limitation of nitrogen in the shale. While the pocket size is chiefly determined by the water retaining ability of the peat compost, a small compost volume can be made more efficient by arranging slabs of slate around the pocket so as to increase its catchment area. In this way more water is directed into the pocket and this is especially important during dry springs and early summers as experienced after the winter planting of 1973/74. THE APPLICATION OF THE TECHNIQUE The pocket planting technique described has already been used for tree planting as part of slate reclamation schemes in North Wales, as at Pant Dreiniog, Bethesda. At the Pantperthog Quarry, children from the Machynlleth High School have carried out pocket tree planting on a previously unvegetated waste tip slope with considerable success. Over three hundred trees of various species were planted, using variations of the technique described, to test the importance of pocket size and substrate type. The enthusiasm of the children has been rewarded with the successful establishment of Birch, Mountain Ash, Sycamore, Red Oak and Lodgepole Pine. The technique was found to be easily applied by the children, being carried out in three stages, the excavation of holes, the filling of the holes with the compost and, after the compost had been moistened by rain, the planting of the tree saplings. With guidance, similar planting could be carried out on a more widespread scale. The technique, whether undertaken by contractors or by volunteers, is a far less expensive way of covering slate tips with vegetation than by the removal and regrading of tips. The end result may be a mixed Birch and Alder woodland with Oak and Sycamore eventually providing the climax community. This is an aesthetic answer to the reclamation problem rather then an amenity one in which the tips are engineered to create landscaped parks and sportsgrounds for the local community. The prospect of engineering all the slate tips of Bethesda, Llanberis and Blaenau Ffestiniog in this way is out of the question because of the enormous amount of money which would be involved. Extensive tree planting on tips has been shown to succeed, the volunteers are there to be called on, all that remains is the provision of the peat compost and the tree saplings. ACKNOWLEDGEMENTS This work was financed by the Natural Environment Research Council. I wish to thank the owners of slate quarries in North Wales, Alfred McAlpine & Son Ltd., Mr. W. E. Roberts and Mr. J. Beaumont, for allowing me to set up trials on their land. I also thank the North Wales Conservation Corps and pupils of the Machynlleth High School for helping too set up large tree planting trials on waste slate tips. The research for this paper was undertaken while at the Department of Botany, University of Liverpool.