Spatiotemporal dynamics ofFloerkea proserpinacoides(Limnanthaceae), an annual plant of the deciduous forest of eastern North America

Abstract

Because environmental filters are temporally and spatially heterogeneous, there often is a lack of significant relationship between the spatial patterns of successive life stages in plant populations. In this study, we determined the spatiotemporal relationships between different life stages in two populations of an annual plant of the deciduous forests of eastern North America, Floerkea proserpinacoides. Demographic surveys were done over a 4-yr period, and experiments were performed in the field and under controlled conditions to test for the effects of various environmental factors on population dynamics. There was a general lack of relationship between the spatial patterns of seed bank and seedling density, and a lack of similarity between their spatial correlograms. This was related mostly to the effects of spatially variable environmental filters operating on germination and emergence. However, environmental filters acting on plant survival were stable through time and contributed to stabilize the density and spatial patterns of the populations. Despite density-dependent presenescence mortality, spatial patterns of seedlings and mature individuals were similar and their correlograms were alike, suggesting that mortality did not fully compensate for density. Estimated fecundity was negatively correlated with population density over the study period. Although flower production started only 2-3 wk after emergence, seed maturation mostly occurred at the end of the life cycle, just before the onset of plant senescence. Yet, individual fecundity was low for an annual plant, i.e., 3.0 Ϯ 0.5 mature seeds/plant (mean Ϯ 1 SE). Seed predation by vertebrates was not significant. Low soil moisture had little effect on the total number of seeds germinating, although it slowed down the germination process. In quadrats where leaf litter was experimentally doubled, seedling emergence was lower than in control quadrats; in quadrats where leaf litter was completely removed, emergence did not differ from that in control quadrats. Susceptibility to drought stress was higher for seedlings than for mature plants. Although the species does not maintain a long-term persistent soil seed bank, other factors, such as density-dependent fecundity and autogamy, may temper population fluctuations through time and reduce the probability of local extinction.

Regeneration of Polylepis australis Bitt. in the mountains of central Argentina

“…Sudden freezing and severe drought, may diminish the survival of seedlings (Wardle, 1971;Wardle and Coleman, 1992;Kitajima and Fenner, 2000). Therefore, the passage from seedling to sapling could be a ''filter phase'' (Houle, 1996;Houle et al, 2001) which limits the recruitment of Polylepis in shrublands.…”

Rapid burial has differential effects on germination and emergence of small- and large-seeded herbaceous plant species

“…Based on Houle et al (2001), we also calculated an emergence velocity index (EVI) according to the following formula: Based on Houle et al (2001), we also calculated an emergence velocity index (EVI) according to the following formula:…”

Conserved simple sequence repeats for the Limnanthaceae (Brassicales)

“…The Limanthaceae (Order Brassicales) is a family of 18 species and subspecies of Limnanthes native to Pacific Western North America (Mason 1952;Ornduff and Carvello 1968;Ornduff 1971) and one species, Floerkea proserpinacoides (false mermaid), native to the northeastern United States and Canada (Houle et al 2000). Wild Limnanthes (meadowfoam) populations fluorish in temporally wet habitats (vernal pools) west of the Sierra Nevada mountain range in California and the Cascade mountain range in Oregon and British Columbia (Mason 1952).…”