Observations of connections between the roots of living trees and root systems of stumps have been reported already in 1900s. In Finland root connections have been found in Birch (Betula sp.), Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.), but there are no studies on abundance of the connections. This investigation studied root connections in a series of naturally regenerated Scots pine stands from seedling stands to mature trees in Southern Finland, and some sown seedling stands.
Root connections were found to be common in naturally regenerated, older stands that had passed the thicket stage. Approximately 21-28% of the trees had at least one root connection to another living tree, dead tree or living stump. Connections were few or absent in seedling stands. Sown seedling groups had many root connections in contrary to naturally regenerated seedling stands. Trees belonging to the dominating canopy class had most root connections. The trees could form a network of up to twenty trees and living stumps. Root connections were more common the larger the tree was or the nearer the trees grew each other. The coalescent roots were often situated near the stem. Experiments showed that water and nutrients transferred in the roots could move from one tree to another. Living stumps from previous fellings were relatively common. In the sites studied, there was in average 178 stumps connected to a living tree per hectare.
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