Micro-variations in yellow birch (Betula alleghaniensis) growth conditions after patch scarification

The abundance of poor quality yellow birch stands resulting from diameter limit cuts poses important regeneration challenges since seed production is uncertain, adequate seedbeds are rare and competition very severe. The present study aims at evaluating variations in seedling growth, temperature, soil humidity and nutrient availability for the whole range of seedbeds created by a patch scarification treatment. In three poor quality stands, soil temperature and humidity, nutrient availability and seedling morphology were monitored on undisturbed forest floor, at different places in 2 m wide scarified patches, and on mounds formed by the displaced material. Even though the study associated some variations in temperature and humidity to different microsite positions, the effect on nutrient availability was more pronounced. Hence, the study found better nutrient availability on mounds in comparison with patches as well as at the border of patches. Soil nutrient availability as measured with in situ ion exchange resin declined very rapidly in the interior of scarified patch (within 5 cm for the border) suggesting that small scarified patches combined with control of vegetation competition should provide a better environment for seedling growth. Growth parameters of yellow birch seedlings were not correlated to measured soil parameters suggesting that there were important effects of uncontrolled factors.