h / d ratio

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The h / d ratio or "the h / d" of trees in forestry is the ratio of tree height (h) to breast height diameter (d).

A tree height of 35 meters with a diameter of one meter at chest height (BHD 1.3) corresponds to an h / d of 0.35.

Individual trees (" solitary plants ") have a lower h / d ratio than trees in the forest. The growth in thickness to ensure stability is not impaired in the free standing by the height growth in the existing structure due to the competition for light.

The average h / d ratio of trees is used in silviculture as an indicator for the stability of the stand against storm events and especially against snow breakage in coniferous wood: the slimmer and taller the trunks, the higher the h / d and the lower the stability and breaking strength . An h / d of 70 is considered stable; above this, the risk of storm damage increases significantly depending on the exposure of the terrain. A significantly lower h / d indicates quality-reducing deforestation and strong knots .

Low h / d ratios can be achieved through early thinning with a reduction in the number of trees in the stand. The remaining trees and especially the cut-out " future or Z-trees " get more light space to be able to grow in the crown and subsequently in diameter. In wind-exposed locations, solitaires are occasionally raised as storm bars in front of endangered stands.

The crown percentage is closely correlated with the h / d ratio .

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