Geographical variation in frond size, rootstock density, and sexual reproduction inMatteuccia struthiopterispopulations in Norway

Abstract

The main aim of this study was to quantify differences in the structure of dense Matteuccia struthiopteris (L) Todaro among geographically separated populations in Norway, and to relate these differences to variation in environmental variables. A stratified random sampling procedure was applied to select 4 m2 quadrats restricted to populations dominated (>75% cover) by the fern. This dimorphic fern can produce three types of leaves (fronds): fertile (sporophyll) and sterile (trophophyll), and in addition also intermediate fronds. In all, 178 populations from different parts of the country were analysed, and in total 9,346 rootstocks were measured. Fifteen percent of the rootstocks were fertile, each producing from one to eight sporophylls, and 2.0% had developed intermediate fronds. Rootstocks with five or more sporophylls were mainly found in Southern Norway. Within the plots, there were major variations in density (10–112), number of small (new) ramets (0–58), total number of sporophylls (0–94) and estimated total fern wet‐weight (0.33–22.8 kg). All new additions to the populations were connected to a mother plant (ramets), and none were of sexual origin (genets). The main environmental variables associated with the variation in population structure were mean July temperature (highly correlated with altitude and latitude), mean precipitation and density of the canopy cover. The density of small ramets and number of intermediate fronds increased from south to north. The latitudinal variation in sporophyll development and maximum trophophyll height was best explained by a unimodal model. There were statistically significant differences in the population structure between the eight studied geographic areas in Norway.

Variations in the population structure and ecology ofMatteuccia struthiopteris

“…Exceptionally, plots of M. struthiopteris were found at sites where the density of the canopy of trees exceeded 80 % (e.g., 17_oNRu rt; Table 1). Increased shading was accompanied by a decrease in the size of trophophylls and the production of sporophylls, which was also reported by other researchers (Odland et al 2006;Odland 2007), with a simultaneous increase in the mean height of trophophylls and sporophylls and the maximum rootstock diameter. The ecological amplitude of plant communities is usually narrower than that of individual species and communities are more sensitive indicators of environmental conditions (Schaffers and Sykora 2000;Diekmann 2003).…”

“…In general, the production of M. struthiopteris sporophylls began upon the emergence of more than six trophophylls higher than 100 cm and when rhizome thickness exceeded 55 mm. Complex relationships between environmental factors were identified by Odland (2007). Matteuccia struthiopteris is a half-shade adapted plant (Ellenberg et al 1991) with an Ellenberg light factor of 5.…”

“…The canopy cover and other environmental factors also affect the amount of rainfall which reaches the forest floor. Odland (2007) believes that the canopy cover is strongly correlated with the rainfall gradient and the average January temperature. These correlations were recorded in central Norway, but they have not been confirmed in studies of M. struthiopteris populations in Western Europe or in western Norway.…”

“…Changes in habitat conditions lead to variations in the morphological parameters of plants (Cook 1985;de Kroon et al 1994;Ellison et al 2004) and plant growth patterns are comprehensive indicators of environmental variation (Odland 2007). Analyses of the allocation of resources to sexual (spores or seeds) and asexual (new ramets) structures in plants provide essential knowledge on the relationships between growth and reproduction as well as on reproductive constraints in a variety of environments.…”

Population Structure of Osmunda regalis in Relation to Environment and Vegetation: An Example in the Mediterranean Area

“…Significant relationships between the surrounding vegetation and the population types indicate that variation in floristic composition can be used as a predictor for the O. regalis population structure to some extent (see also Odland 2007).…”