Population Dynamics of the Wild Daffodil (Narcissus Pseudonarcissus): II. Changes in Number of Shoots and Flowers, and the Effect of Bulb Depth on Growth and Reproduction

Abstract

Variation in the number of shoots and flowers of the wild daffodil (N. pseudonarcissus L.) in an ancient deciduous woodland on Carboniferous Limestone in northern England [UK] from 1969-1978 is described. The number of shoots and flowers was recorded in 56 permanent plots. Variations in number were related to weather characteristics of the spring and summer months of the previous year, and to the edaphic and canopy conditions of the site. Trends in the number of shoots from year to year varied considerably between plots. Under a fully-developed canopy the numbers rose slowly or remained steady, except when they declined in years following hot, dry summers. During the 2nd and 3rd yr after coppicing or clear-felling a marked rise (5-30% yr-1) in number of shoots took place. During the phase before a shading canopy was re-established there was almost always a marked decline in numbers (5-30% yr-1). Flowering in shade environments was limited by late summer drought, excessive wetness in late spring and low total light flux. In open environments, prolonged drought at any time from March-Sept. limited flowering in the following spring. The impact of vertebrate and invertebrate animals on Narcissus plants is outlined, and the effect of some species in determining the position of bulbs in the soil is considered. Bulbs planted at 2 shallower depths (2.5 and 5 cm) produced vegetative daughters at a higher rate than did deeper-planted bulbs (10 and 15 cm depth). Shallow-planted bulbs also produced fewer leaves per shoot, shoots which senesced earlier and a lower bulb weight per shoot. A higher proportion of shallow-planted bulbs produced flowers, but a smaller proportion of these flowers was pollinated. Mortality was similar for bulbs at all depths. Population growth and decline and population changes during a coppice cycle are discussed.