Two types of wood are distinguished in pine and spruce – sapwood and heartwood. According to one of the most common theories, the heartwood formation process can be explained by the aging and dying of parenchyma cells. The proportion of those parenchyma cells which die varies within a species. This proportion is influenced by different factors, for instance –age of tree and growth conditions (forest type). To compare the proportion of heartwood in pine and spruce trunks, depending on the age of trees and forest type, sample plots were established in the stands of different ages (41 – 120 y). For pine, these sample plots were established in Vacciniosa, Myrtillosa, Hylocomiosa forest types but for spruce Myrtillosa, Hylocomiosa and Oxalidosa forest types were chosen. In the case of medium age and mature pine stands the proportion of heartwood in pine is differently influenced by the forest type. In the medium age stands a significantly higher heartwood proportion was found in more fertile forest types, whereas in the mature stands a higher heartwood proportion was found in low fertility Vacciniosa forest type. These differences can be explained by the age when the formation of heartwood starts, since in the poorer Vacciniosa forest type where the growth rate is lower, heartwood formation starts later, but in mature stands the annual increment of heartwood is higher. The forest type does not significantly influence the proportion of heartwood in spruce trunks, but there was a tendency that in Myrtillosa type there was a higher proportion of heartwood.
Keywords: heartwood, pine, spruce, forest type
Authors
Millers M.
Researcher, Forest Faculty, Latvia University of Agriculture
Davidāns M.
Researcher, Forest Faculty, Latvia University of Agriculture
Magaznieks J.
Researcher, Forest Faculty, Latvia University of Agriculture
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