A method of estimating income of nutrients in a catch of airborne particles by a woodland canopy.
Describes a method for estimating the income of K, Mg, Ca, P and Na to a woodland ecosystem in the airborne particles caught by the tree canopy, and gives an account of its use at Meathop Wood, Lancashire. The particles caught at mean canopy height were sampled continuously by a set of natural air-flow impactors fixed to a wind-vane. The impactors, each consisting essentially of a filter paper mounted in a removable section of a horizontal tube of 10.5 cm. internal diameter, were changed monthly. By means of artificially generated aerosols of NaCl solution, comparisons were made in the field between the quantity and type of particles caught by the impactors and by leaves and branches respectively. The monthly income of nutrients per ha. was estimated by combining available data on the dry weight of branches and number of leaves per ha. with data on variations in leaf size obtained by sampling during the growing season. The income of some elements apparently exceeded the amount of those elements contained in rainfall during the same period. The assumptions on which the method was based are discussed; the income of nutrients was probably over-estimated, especially during windy months. The estimated mean velocity of deposition for the elements examined varied from 3.0 to 7.1 cm./sec.KEYWORDS: Nutrients \ plant nutrition \ accumulation \ Nutrients \ plant nutrition \ ecological aspects competition