Sexual Differences in Biomass and Nutrient Allocation in the Dioecious Rubus Chamaemorus

Abstract

I compared the seasonal pattern of biomass distribution and amounts of N and P in male and female ramets of the dioecious perennial herb Rubus chamaemorus L. Two populations, one in an open and one in a shaded habitat, were studied for 2 yr. The cost offruit production in terms of reduction in vegetative growth was estimated in a field experiment.Ramets were larger, but the proportions of aboveground biomass, N, and P that were allocated to reproduction were lower at the shaded site than at the open site. The annual aboveground shoot of R. chamaemorus is either single-flowered or nonfloral. Female flowers had a lower dry mass and nutrient content than had male flowers. However, the ripe fruit had a dry mass, and a content ofN and P, several times as great as those of male flowers. Fruit production interfered with vegetative growth; fruit-producing female ramets produced smaller leaves, and began producing rhizome branchlets later, than male ramets and than female ramets whose flowers had been excised to prevent fruit development. Fruit-producing female ramets had a higher mortality, and a lower probability of flowering in the subsequent year, than had male ramets. The sexual differences in vegetative growth and ramet mortality were smaller in the shaded than in the open habitat. In the shaded habitat, ""50% of the ramets on male clones, and ""30% of the ramets on female clones, were floral.The results suggest that male reproductive effort is greater than female up to the time of flowering, but that the total female allocation to reproduction is greater than the total male even at relatively low levels of fruit set. The predominance of R. chamaemorus populations with male-biased floral sex ratios is proposed to be the result of males having both a greater competitive vigor and a higher flowering propensity than females.

Consequences of clonality for sexual fitness: Clonal expansion enhances fitness under spatially restricted dispersal

“…23). Indeed, clonality might more strongly trade-off against investment in female sex function than male sex function (27,39). If this is generally true and trade-offs between clonal growth and pollen production are usually weak, we predict that this should have two contrasting effects on the fitness of clones via their pollen production.…”

Mineral Balance Plasticity of Cloudberry (<i>Rubus chamaemorus</i>) in Quebec-Labrador Bogs

“…The foliar N/P mass ratio is a well-documented indicator of nutrient limitation to the growth of wild species: plant growth would be N-limited at N/P ratios < 14, P-limited at N/P ratios > 16, and co-limited by N and P at intermediate values [12]. By comparison, the N/P ratio in cloudberry leaves was in the range of 12 to 14 in Sweden [15], and of 7 to 11 in Scotland [14] and Norway [16,17].…”

Microclimatology and ecophysiology of the urban vegetation of a city with tropical climate modified by altitude in Mexico

“…In this way, it is necessary to consider the temporary variation to improve our estimation of the edge effects on the reproduction of studied species. For example, although we could not currently detect a bias between sexes, which, by the way, may depend on several factors as differences between male and female plants in the age or size to the sexual maturity, or differences in the flowering frequency between plants of different sexes (Meagher 1980), to long term, bias in sexual rates between edge and interior of fragments may be expected, because in contrast with male plants, survival rates of female plants can be decreased in stressed environments as consequence of a less resources allocation to the survival and a high allocation to the reproduction (e.g., Agren 1988, Gehring & Linhart 1993, Yu & Lu 2011. Additionally, it is important to consider other factors that can influence juvenile densities in the edge and the interior of the fragments.…”