Community-wide germination strategies in a temperate rainforest of Southern Chile: ecological and evolutionary correlates

Abstract

Delayed seed germination (‘dispersal in time’), as a component of a plant’s germination strategy, was studied in dicotyledoneous species of a temperate rainforest flora in Chiloé Island (42°30′S), southern Chile. The objective of this investigation was to assess, for this temperate rainforest flora, what proportion of interspecific variation in the time of seed germination—measured in days since the onset of seed dispersal in space—could be attributed to the plants’ historical and phylogenetic background and what proportion was associated with life history and ecological attributes such as seed mass, life form, dispersal syndromes and dispersal periods. To characterise germination times for 44 species from Chiloé forests (n = 150 seeds sowed per species in laboratory assays), we computed the mean germination time (GT), in days since sowing, for all seeds germinated of each species. Seeds were taken from the plants at the onset of dispersal and germinated in Petri dishes at 10/20°C. Considering all species, GTs varied between 3 and 385 days and presented an L-shaped frequency distribution. One-way ANOVAs measured the effects of each factor across all other variables. Two-way ANOVAs were used to assess significant interactions between factors. Multifactorial ANOVAs were used to evaluate the independent effects of each of six historical, phylogenetic and ecological factors on GT and to detect associations between factors. In one-way ANOVAs, phylogenetic grouping (at or above order) explained 12% of the variance in GT; dispersal period (summer v. mainly autumn dissemination of ripe seeds), biogeographic element (endemic, austral, neotropical or cosmopolitan) and dispersal syndrome (fleshy v. dry propagules) explained 7, 6 and 5% of the variance in GT, respectively. The factors life form (trees, shrub and woody vines combined, herbs and non-woody epiphytes) and seed mass (light v. heavy) explained the 4 and 2% of the variance in GT, respectively. Taxa related to Ranunculales presented the longest mean GT (148 days). Endozoochorous species had a more delayed germination than species with other dispersal syndromes. Herbs and non-woody epiphyte species showed mean GT (41 days) significantly shorter than trees and shrubs plus woody vines combined (86 and 85 days, respectively). All interactions in two-way ANOVAs were significant. Multifactorial ANOVAs revealed that the three major factors contributing to differences in GT in this temperate rainforest flora were phylogenetic relatedness, dispersal syndromes and life form (7, 6 and 6% of the interspecific variation, respectively). In this analysis, biogeographic element, dispersal period and seed mass were not significantly related to GT. For the factors examined, failure-time analysis, which takes into account all viable seeds not germinating in laboratory assays, confirmed results from multifactorial ANOVAs.

Seed mass and germination in an alpine meadow on the eastern Tsinghai–Tibet plateau

“…This result is in accord with the former studies. For example, Seven species of Alstroemeria that grow in different mountain and lowland habitats in South America exhibited similar germination strategies, regardless of their habitat of origin (see Figueroa and Armesto 2001); Baskin et al (1993) reported analogous results when dormancy types were compared among species in the family Asteraceae; Species belonging to the Arcto-Tertiary flora presently inhabiting deciduous North American forest, had germination strategies that matched those of congeneric species presently occurring in East Asia (Baskin and Baskin 1998).…”

“…For example, phylogenetic closeness explained much interspecific variation in breeding systems, seed mass, flowering phonologies, fleshy-fruit traits and reproductive syndromes in Mediterranean, tropical and temperate floras (see Figueroa and Armesto 2001). For example, seed germination rates of species belonging to the same plant families in Sheffield, England, were more similar than those of species in different families (Grime et al 1981); Figueroa and Armesto confirmed that phylogenetic relationships significantly influenced GT (mean time of seed germination in days from sowing) for species in the forest flora of Chiloé ; The phylogenetic pattern of seed mass was also previously shown in different floras (Mazer 1990;Lord et al 1995).…”

Effect of phylogeny, life history and habitat correlates on seed germination of 69 arid and semi-arid zone species from northwest China

“…Comparative surveys have shown that germination behavior is also related to other life history traits such as seed mass (Mazer 1989;Shipley and Parent 1991;Jurado and Westoby 1992;Guo et al 2000;Pearson et al 2002;Bu et al 2007), seed dispersal (Willson and Traveset 2000) and life form (Gross 1984;Figueroa 2003). In addition, some of the variance in life history traits between species is associated with phylogeny (Mazer 1989(Mazer , 1990Leishman et al 1995;Figueroa and Armesto 2001;Figueroa 2003;Zhang et al 2004;Simons and Johnston 2006;Bu et al 2007), and this association is often attributed to phylogenetic constraints (Kochmer and Handel 1986). Therefore, to assess the role of natural selection on seed germination at the community level, we should take into account as many variables as possible when measuring the effect of any single variable.…”

Allelopathic effect of medicinal plant Cannabis sativa L. on Lactuca sativa L. seed germination

“…The germination index (GI) is based on number of seeds that germinated and the germination rate. These parameters were also calculated from the formulas proposed by (Figueroa and Armesto, 2001;Bu et al, 2007;Wu and Du 2007).…”