Needle retention and needle loss of Scots pine in recent decades of Thetford and Alice Holt, England
1994
Jalkanen, R.E. (The Finnish Forest Research Institute, Rovaniemi, Finland.) | Aalto, T.O. | Innes, J.L. | Kurkela, T.T. | Townsend, I.K.
Fourteen Scots pines (Pinus sylvestris L.) were felled in Thetford and Alice Holt forests, southern England, for needle retention studies. In the field, the main stem of each tree was divided into annual sections, with each section being reduced to 30 cm long bolts or less, omitting branch whorls and using the internodal part of each annual shoot. The bolts were then planed one annual ring at a time to reveal the location of needle traces. In the summers of 1950-1990, the average needle retention was 2.6. Average needle retention varied annually from 1.5 to 3.3. There was a slight reduction in needle retention following high values at the end of the 1960s, and this accelerated during the 1980s. Needle retention history was similar at both Thetford and Alice Holt. The amount of annual needle loss varied between 0.3 and 1.6 needle sets, and the 40-year average of 1.02 sets indicated a long-term reduction in the number of needle sets during the lifetime of the trees
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