Are Plant Populations Seed Limited? A Critique and Meta‐Analysis of Seed Addition Experiments

Abstract

We examine the relative importance of processes that underlie plant population abundance and distribution. Two opposing views dominate the field. One posits that the ability to establish at a site is determined by the availability of suitable microsites (establishment limitation), while the second asserts that recruitment is limited by the availability of seeds (seed limitation). An underlying problem is that establishment and seed limitation are typically viewed as mutually exclusive. We conducted a meta-analysis of seed addition experiments to assess the relative strength of establishment and seed limitation to seedling recruitment. We asked (1) To what degree are populations seed and establishment limited? (2) Under what conditions (e.g., habitats and life-history traits) are species more or less limited by each? (3) How can seed addition studies be better designed to enhance our understanding of plant recruitment? We found that, in keeping with previous studies, most species are seed limited. However, the effects of seed addition are typically small, and most added seeds fail to recruit to the seedling stage. As a result, establishment limitation is stronger than seed limitation. Seed limitation was greater for large-seeded species, species in disturbed microsites, and species with relatively short-lived seed banks. Most seed addition experiments cannot assess the relationship between number of seeds added and number of subsequent recruits. This shortcoming can be overcome by increasing the number and range of seed addition treatments.

The Ecological Characteristics of Seed Germination and Seedling Establishment of <i>Manglietia patungensis</i>: Implication for Species Conservation

“…Many tree seeds are dormant at the time of dispersal, requiring a period of after-ripening before seeds germinate [34,35]. During that time various environmental stresses, animal feeding and pathogenic infection may make seeds lose viability [36,37]. Seeds of M. patungensis fall into the soil in autumn, and germinate in the spring next year.…”

Dispersal and establishment both limit colonization during primary succession on a glacier foreland

“…However, it is increasingly recognized that both effects are often prominent in a community (Clark et al 2007). This study suggests that dispersal and establishment are multiple sieves that limit colonization.…”

“…In primary succession, many species fail to colonize disturbed areas for decades after the disturbance (Wood and del Moral 1987;del Moral and Eckert 2005). Such failures may be due to either seed limitation or limitations on establishment (Turnbull et al 2000;Clark et al 2007). …”

“…Seed limitation can result from poor dispersal (Primack and Miao 1992) or limited seed production (Clark et al 2007). In early succession, seed limitation of late-seral species is likely due to lack of dispersal from other sites, since no reproductive individuals are present.…”

“…Seed and establishment limitations may interact to delay colonization (Eskelinen and Virtanen 2005;Clark et al 2007). The few studies that have experimentally studied colonization limitation on glacier forelands have found a combination of seed and establishment limitation (Chapin et al 1994;Niederfriniger Schlag and Erschbamer 2000).…”