Quantity and Quality of the Annual Production of Shoots and Flowers by Calluna Vulgaris in North-East Scotland

Publisher Website
Google Scholar
Abstract
(1) Seasonal and annual variations in the production and chemical composition of shoots and flowers of Calluna vulgaris (L.) Hull were studied over a 6-year period on eight fenced plots at Kerloch, Kincardineshire. The plots had last been burned at intervals ranging from 2 to 40 years. (2) Annual production of shoots and flowers increased in successive years after a fire, until nearly complete ground cover had been restored in 4-10 years. Thereafter, the mean annual production (c. 200 g m-2 of shoots and 45 g m-2 of flowers) did not differ significantly amongst stands of different ages up to 40 years. (3) However, production varied widely from year to year; shoot production was related to daily mean air temperature and total rainfall during the period of most active growth (May-August), and flower production was related to temperature in April, when growth began. (4) Application of ammonium nitrate to the soil enhanced shoot production, but ground mineral phosphate had no effect. (5) The amount of nutrients (N, Na, K, Ca, Mg, P and soluble carbohydrate) in whole stands of C. vulgaris increased with age until it levelled out at 15-20 years. However, the concentration of nutrients in the shoot tips from which herbivores select their diet declined annually to the fourth year after burning, and thereafter did not change appreciably. The levels of most nutrients were highest in midsummer, at the time of most rapid growth.