effects of nutrient availability on foraging in the clonal herb Glechoma hederacea

• Published in: The Journal of ecology 1987-03, Vol.75 (1), p.95-112
• Main Authors: Slade, A.J, Hutchings, M.J
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; branching; Chlorophylls; Ecophysiology; Foraging; Fundamental and applied biological sciences. Psychology; Glechoma hederacea; growth forms; habit; Internodes; Leaf area; Leaves; nutrient availability; Petioles; Plant growth; Plants; Plants and fungi; Stolons
• ISSN: 0022-0477; 1365-2745
• DOI: 10.2307/2260538

(1) The growth forms of genetically identical clones of the perennial herb Glechoma hederacea were compared under three soil nutrient regimes: (i) all ramets were rooted in nutrient-rich sand, (ii) all ramets were rooted in nutrient-deficient sand, (iii) all ramets produced by one primary stolon were rooted in nutrient-rich sand while all ramets produced by the other stolon were rooted in nutrient-deficient sand (split treatment). (2) Clones growing in nutrient-rich sand had short stolon-internodes, copious branching and a rapid accumulation of many large ramets with large leaf-areas. Proportional allocation of dry weight to leaves and petioles was high, whereas allocation to stolons and roots was low. (3) Clones growing in nutrient-poor sand had long stolon-internodes, less frequent branching and a few small ramets with small leaf-areas. Proportional allocation of dry weight to leaves and petioles was low, whereas allocation to stolons and roots was high. (4) Results for the split treatment were intermediate between those of the two singular treatments. There were few significant differences between the half of the split treatment receiving a given treatment and the complete clone receiving the corresponding treatment. Analysis of the split treatment provided no evidence for integration between primary stolons subjected to different nutrient levels. (5) Leaf areas, stolon lengths, number of ramets, stolon branching and dry weight of the primary structures and whole clone increased with clonal age in all treatments. Rate of increase was highest for the nutrient-rich clones, and intermediate in the split treatment clones. (6) The phenotypic plasticity of growth revealed in this experiment may be beneficial since it enables Glechoma hederacea to consolidate its occupation and exploitation of favourable sites (intense foraging), and to pass rapidly through less favourable sites, which may increase the probability of escape into more favourable sites (extensive foraging). The lack of integration between primary stolons may be beneficial in enabling ramets in favourable sites to develop rapidly rather than diverting their accumulated resources to ramets in less favourable areas, which might limit clonal expansion.