Growth Response to Different Levels of Soil Moisture and Soil Fertility in Four Winter Annual Species during Their Life-Cycle

Abstract

The effect of three different soil moisture levels and two soil fertility levels on the growth, biomass allocation and reproductive effort of four winter annual plant species from the open dune habitat i.e. Aira praecox, Cerastium arvense, Erophila verna , and Veronica arvensis , has been investigated. Soil moisture has a considerable effect on the growth and reproduction of all species except Veronica arvensis , in which an increasing soil fertility seems to be of overriding importance. In the experimental period (27-30weeks), only Cerastium semidecandrum and Erophila verna completed their life-cycle and produced seeds. In these species absolute seed biomass and number per plant are markedly depressed by a low soil moisture level. In contrast to Erophila verna , the values of these parameters increase in Cerastium semidecandrum when the soil fertility is high. Mean seed weight was not affected by the treatments. Regarding the different niches of these winter annual species in the dune habitat, we discuss in how far the niches of these annuals represent different strategies or may be considered one particular strategy sensu G rime (1979).