A site has been selected, drainage instituted and a series of plots designated 

 on which a long range study of nutrients, of tree growth and of ground cover can 

 be conducted. In the course of this preparatory work, promising new ditching 

 techniques were found which will assist in the rehabilitation of wet sites. 



A report has been submitted for publication concerning the effects of logging 

 and burning upon a poorly drained organic site. There will be a further expansion 

 of this study during the coming year. Three translations on peatland forestry from 

 Russia, Finland and Norway have been submitted for publication, 



CENTRAL FOREST RESEARCH UNIT 



The work of this unit consists of both field and laboratory studies of problems 

 of tree nutrition related particularly to forest disturbance and regeneration. It also 

 includes studies of the productivity ecology, and racial variation of red spruce. 

 Work on smelter fume pollution in relation to forest soils and vegetation has been 

 concluded for the present. 



Tree Nutrition, Forest Disturbance and Regeneration. Studies are under way 

 on the effects of prescribed burning and scarification upon nutrient release in the 

 soil and the uptake of these nutrients on the growth of tree seedlings on different 

 landtypes. 



Productivity Ecology of Red Spruce. Red spruce has characteristics which 

 make it very useful in improving the productivity of derelict tolerant hardwood 

 and mixedwood stands. This study is expected to elucidate the silvics and silvi- 

 culture of this species and provide definitive information of growth potential for 

 planting programs. 



The study is designed to measure growth and productivity of red spruce in 

 pure and mixed stands on a complete range of physiographic sites across its range 

 in Ontario. It is hoped to provide explanations of differences in spruce growth as 

 related to nutrient uptake from forest soils. In addition, total productivity (dry 

 weight production) and ground flora relationships are being investigated. 



By using computer techniques, it is intended to construct a mathematical 

 model to describe, explain and predict the foregoing relationships. Comparative 

 measurements are already being made on white and black spruce when these 

 species occur in association with red spruce. 



Work is also proceeding on the racial variation in spruce in order to find the 

 best ecological characteristics. The relationships of genetic variation to nutrition 

 and growth in spruce are being investigated by measurement and analysis of 

 different provenances and species, on the same and different sites. Early indications 

 are that natural or artificial hybrids between red and black spruce, while possibly 

 possessing some hybrid vigour, are not nearly as desirable as the parent trees. The 

 hybrids are exceedingly rough and limby. 



A large scale experimental underplanting has been established and assistance 

 to the Timber Branch on the establishment of seed production areas is continuing. 



SOUTH CENTRAL FOREST RESEARCH UNIT 



The objective of this unit is to provide information for the management of 

 the important commercial tree species that occur in south central Ontario. These 

 are sugar maple, yellow birch, white and red pines. 



Sugar Maple Studies — Growth and Quality. Studies are being conducted to 

 follow the development of defect in Maple and to learn how defect is associated 

 with growth and environment. The objective is to define the conditions under 

 which the optimum growth of quality maple wood can be attained. 



252 



