Seed production in grassland species: Morpho‐biological determinants in a species‐rich semi‐natural grassland

Abstract

Studying the seed production of herbaceous species can help to conserve grassland habitats and re‐create new high‐value grassland surfaces. Studies on grassland seed production have focused mainly on individual species and traits, without characterizing their relative importance at the plant community level. The aim of this study was to investigate the entire seed production process of the main species in a temperate grassland. Fertile shoots (FS) of twenty‐nine grasses and forbs were collected over 4 years and analysed for sixteen traits that determine inflorescence size, seed production and seed quality. The per cent viability played a predominant role in determining the total production of viable seeds. Forbs showed a range of reproductive strategies, including variable distribution of flowers among growth periods, number of inflorescences per FS and relationship between seed size and FS density in the grassland. The flower production for grasses was concentrated in the first growth period, but this limitation was mitigated by a higher seed dormancy. The number of viable seeds per FS and seed size were important components of the reproductive strategy of forbs, with heavy‐seeded species being characterised by high individual densities in the community, but producing few seeds per FS. Light‐seeded species showed an opposite pattern. The results suggest that when using seeds from semi‐natural grasslands for ecological restoration, special attention should be paid to the seed amount, germinability and viability of forbs, as they seem to depend more on seed reproduction and have a lower ovule to seed transformation efficiency.

Seed production of semi‐natural grasslands: Amount and variability in an unfertilized upright brome and a fertilized tall oat‐grass meadow

“…The three samples of 10 FSs collected at the species optimal seed maturation stage at the plot level were analysed in detail in the laboratory to determine the potential seed production of individual FSs of each species in each growth period according to the procedure described by Scotton (2018b). In brief, the number of inflorescences per FS, flowers per inflorescence, ovules per flower, percentage of ovules transformed to seed (ovule site utilization, OSU) and percentages of germinability and viability were determined.…”

“…The present study presents results on the seed production considered at the whole meadow level, whereas results obtained for the individual reproductive traits at the fertile stem level, including relationships among traits and grasses versus forbs comparisons for individual traits and gamic regeneration strategies, were published in a previous paper (Scotton, 2018b).…”

“…Clark and Redmann, 1997) or FSs containing ripe seeds (e.g. Scotton, 2018b; Scotton & Ševčíková, 2017) from sampling areas harvested at subsequent times within the growing season. These procedures did not consider seed shattering that occurs before collection and did not allow the description of seed production temporal patterns.…”

“…The same reproductive trait can play different roles in different groups of species. For example, seed viability was found to characterize positively grasses producing many light seeds per FS, but forbs producing few heavy seeds with low filled seed to ovule ratio (Scotton, 2018b). Furthermore, the relative importance of each component of seed production can change depending on the species, location and management and may determine the ecological success of each species (Pearson and Ison, 1987).…”

Seed traits of species from South Brazilian grasslands with contrasting distribution

“…Research on seed traits provides important knowledge for biodiversity conservation and can contribute to decision-making regarding in situ management of species, populations or communities, and ex situ seed conservation and ecological restoration (Barak et al 2018;Saatkamp et al 2018). Knowledge about seed production, size and mass (Paulů et al 2017;Alstad et al 2018;Chen et al 2018), and recognition of characteristics related to germinability, may be key for determining species suitability for restoration (Perring et al 2015;Carta et al 2016;Ladouceur et al 2018;Scotton 2018). In general, seed traits are likely to be more similar in more closely related species due evolutionary conservatism (Burns & Strauss 2011;Gabrielová et al 2013;Zhang et al 2014).…”