Control of vegetation succession by means of soil fabrics.
Describes experiments on the use of fabrics placed on the soil surface or within the soil profile to prevent invasion by tree species. In a greenhouse experiment, Quercus rubra acorns were sown in a loam containing (a) galvanized iron mesh, 3 or 6 mm., or (b) fibre-glass mesh, 1.5 mm., placed 3 cm. below the soil surface with the object of constricting the tap-roots of the seedlings. Assessment 11 months after sowing showed that meshes had no significant effect on seedling fresh weight, and caused no mortality. The percentage of seedlings with constricted tap-roots rose sharply with increasing size of seedling in (a) but not (b). With (a) the tap-roots of all seedlings above a certain weight were constricted, whereas with (b) many seedlings established multiple connections through the mesh, and many had tap-roots with large swellings above and below the mesh. It is suggested that reconnection growth in (a) was prevented by Zn toxicity. In a field experiment in Connecticut, (a) and densely woven plastic cloth (c) were placed at various depths in the surface soil of a mowed fallow field subject to invasion by Fraxinus americana. A seedling count after three years suggested that (C) was an effective barrier to the establishment of F. americana and had a negligible effect on the herbaceous cover. Data after five years indicated that constriction of F. americana by (a) is associated with stomatal closure and dieback of the shoot. KEYWORDS: Fraxinus americana control \ Quercus rubra Q. borealis var. maxima control \ Weed trees \ shrubs control mechanical