Production and nutrient cycling in three Scottish oak woods on contrasting soils

Abstract

Studies were made in three ancient Scottish Oak woods on contrasting soils: Ross (podzols) and Gartfairn (gleys) near Loch Lomond, and Methven (brown earths) near Perth. The annual rainfalls (mm) are : Ross and Gartfairn, 1700; Methven 700. Soil nutrient (0-10 cm) contents were ranked Methven> Gartfairn> Ross> except for total nitrogen which was Gartfairn> Methven> Ross. Each wood was sampled from three 1000 m* plots. Tree (> 5 cm dbh) density and basal area were : 343 ha and 21.7 m* ha** for Ross; 410 ha** and 30.4 m* ha** for Gartfairn; and 280 ha** and 37.8 m* ha** for Methven. Small litterfall, measured in eighteen traps per plot, had mean values (kg ha**): Methven, 5368; Gartfairn, 4476; and Ross 3607. The values are in the same rank order as soil nutrients (except nitrogen). Litter layer mass was highest in Ross and least in Gartfairn while its nutrient content (for all elements) was least in Ross and highest in Methven. The turnover rates (kl) of litter mass and nutrients were least in Ross and (except for nitrogen) highest in Gartfairn. Studies of leaf decomposition were made in bags of two mesh sizes (64* and 5mm) of 144 cm* and in open frames of 225 cm*. Leaf mass was lost fastest in the frames and slowest in the fine mesh, except for Ross where there was no difference between the two meshes. Coarse-mesh decomposition was fastest in Gartfairn and slowest in Ross; fine-mesh decomposition was fastest in Ross, slowest in Methven. There was a linear relationship between mass of litter lost and time elapsed. The litter mass losses were often significantly correlated with the initial nutrient content. Patterns of nutrient accumulation and release differed between elements, sites, and containers. Nutrients were usually released faster in coarse-mesh compared with fine-mesh bags.