Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

On the suffruticose vegetation [Calluna, Vaccinium, etc.] of forest land.

Abstract

(i) Distinguishing features of the woods of Vaccinium myrtillus, V. uliginosum, V. vitisidaea, Empetrum hermaphroditum and Calluna vulgaris are discussed and illustrated. In general, the woods of these species are characterized by very short tracheids and libriform cells, and are heavy. (ii) Data from practically pure old communities of the Vaccinia and Calluna show that about half of the dry weight of the plants is situated in the humus layer, which is interwoven with stems and roots. Further data from 5 forest types of the Ulvsjoberg indicate that both dry weight of aerial parts and annual litter production decrease in the order: Calluna type, Empetrum type, Vaccinium uliginosum/Calluna bog-forest type, Vaccinium type, Myrtillus type. The Calluna type had a dry weight per ha. (aerial parts) of 14, 400 kg. and an annual litter production per ha. of 2, 600 kg., corresponding figures for the Myrtillus type being 5, 400 and 800 kg. per ha. (iii) Results of chemical analyses are presented and it is emphasized that Composition varies widely in different parts of the plants, e.g. the content of mineral constituents such as CaO, K2O and P2O5is highest in leaves of the year an lowest in the underground portions, whereas the reverse is true of lignin content. Leaves of the species examined had high sugar contents (14-18 per cent. of the dry weight), and those of Empetrum were characterized by a high content of ether-extractables (about 19 per cent. of the dry weight). CaO, K2O and P2O5, contents were highest in leaves of V. myrtillus and lowest on the whole in those of Calluna. (iv) In spite of a low mineral-nutrient content, the Calluna type will add the greatest supply of such nutrients to the humus layer, owing to the sheer quantity of litter produced per unit area. Calculations are made to show the supply, per ha. and year, of materials to the humus layer, but it is stressed that in the types concerned decomposition is slow; furthermore, the amounts of minerals taken up by the plants far exceed those in the litter and are largely accumulated in lignified stems and roots which also decompose slowly. (v) Yields of mineral nutrients to be expected from the burning of the aerial parts are calculated for each of the Ulvsjoberg types. For the Calluna type these amount to (kg./ha.) CaO 68.1, K2O 55.9, P2O5 28.4, and for the Myrtillus type the corresponding figures are 43.1, 25.7, and 10.7. Burning of such vegetation may thus be expected to have the effects of a fairly good application of mineral fertilizers, and other presumed beneficial effects would be acceleration of N transformation in the humus, a green-manuring effect by the dead mycorrhizal roots, elimination of competition and of interception of precipitation. (vi) Abundance of the species dealt with is usually an indication, in productive forest stands, of poor utilization of the productive capacity of the soil, and it is important to have as little as possible of such ground vegetation. Thin and overmature stands with dense suffruticose ground cover should be regenerated as soon as possible and the aim should be to have dense stands of young trees and to use short rotations. KEYWORDS: Burning \ heather \ Ground flora litter production and turnover \ nutrients \ Heather turnover \ nutrients \ heathlands \ soil and vegetation \ Nutrients, plant turn over \ ground flora \ Weeds, forest heather