Spacing, also know as Pre-commercial thinning, has one of the best returns on investment of all forest management activities. In order to get a good rate of return, the timing of the thinning is critical; if it is done too early competition will establish in the open areas and compete for light and nutrients with the desired species; if left too late the crop trees will not release properly - they will not respond with an increased growth rate.  As a general rule the softwood trees must be between 2 and 7 metres in height and have more than 10,000 stems per hectare in order to qualify for pre-commercial thinning. 

This is an excellent program with wide appeal.  There are few woodlots that cannot take advantage of pre-commercial thinning since most naturally established stands will regenerate with too many seedlings.  If Nature is left to thin the stand through natural selection, the stand will go into a period of >stagnation= when no growth or even negative growth will occur.  By intervening at the right time, this stagnation can be avoided and growth will actually continue to accelerate until the stand reaches maturity and is ready to be harvested.