Are plant populations seed‐limited? A review of seed sowing experiments

Abstract

Minireviews provides an opportunity to summarize existing knowledge of selected ecological areas, with special emphasis on current topics where rapid and significant advances are occurring. Reviews should be concise and not too wide-ranging. All key references should be cited. A summary is required.

Floral adaptation and diversification under pollen limitation

“…Although Kelly et al (2007) and Price et al (2008) recently demonstrated both pollen and seed limitation for two species, supporting this assumption, about half of the seed-addition experiments on 90 species reviewed by Turnbull et al (2000) found no evidence of seed limitation, especially in established communities, indicating that other processes govern abundance in many plant populations. In such cases, PL is of no ecological (or conservation) consequence.…”

Spatial patterns of seed dispersal, their determinants and consequences for recruitment

“…Many sowing experiments find a significant effect of the experimental increase in seed abundance upon population recruitment and, therefore, on community composition 45 . However, because sowing is usually done at a single density (not necessarily saturating) and…”

“…46). The performance of such experiments at appropriate spatial and temporal scales is difficult, especially where large and long-lived species are involved; not surprisingly, most seed-manipulation studies have been conducted on grasses and forbs 45 .…”

Insect‐plant interactions on a planet of weeds

“…A simple test of seed limitation is to manipulate levels of seed production and measure a change in plant abundance. A review of seed addition studies spanning 27 studies incorporating 90 species found that approximately 50% of seed augmentation experiments show evidence of seed limitation (Turnbull et al, 2000). These studies show that seed limitation tends to occur more commonly in early successional habitats and in early successional species.…”

“…These studies show that seed limitation tends to occur more commonly in early successional habitats and in early successional species. The recommended protocol for seed addition experiments, modified from Turnbull et al (2000) is to (1) estimate seed a output of a natural population and make seed addition some specified multiple of natural seed rain to facilitate comparisons among studies; (2) manipulate seed density over a sufficient range; (3) monitor response throughout the life cycle, at least to the adult stage; (4) manipulate seed-feeding herbivores as part of the design, perhaps combining enhanced, control, and diminished seed predator populations in combination with enhanced, control, and diminished seed rain; and (5) conduct seed additions on appropriate spatial and temporal scales, based on the life history of the organism, which distributes seed in space (dispersal) and time (dormancy, perennial life style, and iteroparity). I emphasize the last point because local seed sowing experiments may underestimate the opportunities available to organisms with complex life cycles living in a spatially and/or temporally variable environment, and may therefore underestimate the true expectation of reproductive success (McEvoy, 1996).…”