Corynephorus Canescens (L.) P. Beauv. as a Model for the Ammophila Problem

Publisher Website
Google Scholar
Abstract
The sand-dune grasses, Ammophila arenaria and Corynephorus canes cens decline in vigor with the onset of conditions of dune stability. Corynephorus, because of its small size, was used as an experimental model for studying the problem. Analysis of the response of Corynephorus to its environment, field transplant experiments, glasshouse pot-, and split-root-experiments were carried out. From these the decline in vigor was shown to be a consequence of morphology and growth pattern which, under stable dune conditions, ultimatley result in the production of new adventitious roots above the sand-surface, an environment in which they do not develop because of lack of moisture. Plant growth and longevity is then dependent on the existing roots which become functionless by 12 months of age, their cortices having completely disintegrated. The existing roots cannot maintain growth at the rate which is possible when new roots are developing and supplying the increasing number of tillers. Hence the decline in vigor. This is aggravated, in the presence of Carex arenaria, by competition for water. Vigorous growth where sand accretion occurs is the optimal growth for the species, the moisture necessary for new root development being made available at the site of root production, the sand providing the physical medium in which the moisture is held. Ammophila arenaria differs in detail from Corynephorus; on stable dunes, the current site of adventitious root production is never obviously positioned above the sand-surface, and Ammophila is invariably accompanied by other species there. Its decline in vigor results from inadequate replacement of old roots by developing new roots probably due to competition, initially for water and consequently for nutrients, by the roots of other species in the surface sand layers where the site of new root production is positioned. Root development may be additionally impaired by the drying out of the surface sand layers during summer. The problem is seen to have wider implications for pioneer species and for pattern development in many perennials.

This publication has 1 reference indexed in Scilit: