Growth of a sitka spruce plantation: Spatial distribution and seasonal fluctuations of lengths, weights and carbohydrate concentrations of fine roots

Abstract

As part of an investigation into the primary production of a forest the activity of fine roots was estimated by taking weekly soil cores from 24 May to 27 September in the 11 year of growth of a plantation of Picea sitchensis. Distinct maxima were found in 1) starch and soluble carbohydrate concentration in the root, mid-June, 2) root weight/soil volume, early July, and 3) root length/soil volume, late July with a second maximum in early September. However, root concentrations in the soil were the same at the end as at the start of the period and it is suggested that the fine root system of the forest had reached a dynamic equilibrium. The growth of the fine root system, from mid-May to late July is described as a continuous process; there is no indication that root activity ceases during the period of shoot elongation. Two populations of fine roots were found in the forest. In the surface horizons of the soil roots classified with a diameter < 0.5 mm have a greater mean diameter, more root tips per unit length and are present in greater concentrations than in the peat and mineral soil below. Higher concentrations of root were found both in regions of soil which had been disturbed by preplanting cultivation and in regions close to the tree trunk. re]19760304 © 1977 Martinus Nijhoff Publishers.