A morphological and mechanical study of the root systems of suppressed crown Scots pine Pinus sylvestris

Previous studies have shown that root system asymmetry can greatly affect the stability of trees. In this study mechanical investigations of the stability and anchorage symmetry of suppressed crown Scots pine (Pinus sylvestris) trees growing in clay soil were combined with morphological investigation of the lateral root system. It was found that most of the trees showed different resistance to pulling forces from different directions (anchorage asymmetry) which, however, was not correlated with lateral root system asymmetry. This suggested that the lateral roots were not major components of anchorage, a finding supported by scaling data and by visual observation of uprooting. Instead, tap and sinker roots probably provided the majority of anchorage, and their non-circular shape must have caused the anchorage asymmetry. Root system asymmetry was more common in trees on the edge of the stand than in trees inside the stand, a fact probably related to the reduced root competition outside the stand.