Costs and benefits of masting: economies of scale are not reduced by negative density‐dependence in seedling survival in Sorbus aucuparia

Abstract

Masting is a widespread reproductive strategy in plants that helps to reduce seed predation and increase pollination. However, masting can involve costs, notably negative densitydependent (NDD) seedling survival caused by concentrating reproduction in intermittent events. Masting benefits have received widespread attention, but the costs are understudied, which precludes understanding why some plant species have evolved intense masting, while others reproduce regularly.We followed seed production, seed predation (both 13 yr), and seedling recruitment and survival (11 yr) in Sorbus aucuparia. We tested whether NDD in seedling survival after mast years can reduce the benefits of pulsed reproduction that come through predator satiation.Seed predation rates were extreme in our population (mean = 75%), but were reduced by masting. The commonly accepted, but untested, assertion that pulsed recruitment is associated with strong NDD was unsupported. Consequently, the proportion of seedlings that survived their first year increased with fruit production. This provides a rare test of economies of scale beyond the seed stage.Our results provide estimation of the costs of mast seeding, and indicate that these may be lower than expected. Low masting costs, if common, may help explain why masting is such a widespread reproductive strategy throughout the plant kingdom.

Variation in biotic interactions mediates the effects of masting and rainfall fluctuations on seedling demography in a subtropical rainforest

“…We showed that temporal variation in the abundance of new recruits and total rainfall significantly affects seedling vital rates, and that these effects are mediated by changes in the strength of biotic interactions. Our findings are in accordance with the Economy of Scale hypothesis, mainly reported at the seed-to-seedling stage and rarely investigated at the seedling stage after their emergence (but see Hett, 1971;Huang et al, 2021;Seget et al, 2021). We further showed that years of higher recruitment experience reduced seedling growth, likely because of increased competition for resources.…”

“…In addition, years of higher seed production might produce seeds with higher seed mass and nutrient reserves due to greater pollination efficiency, thus increasing seedling survival (Sork, 1993). Whether the predictions of the Economy of Scale hypothesis hold true after the germination phase has been rarely tested (Hett, 1971; Huang et al, 2021; Seget et al, 2021).…”

Global patterns in the predator satiation effect of masting: A meta-analysis

“…However, this is likely a simplification. Even generalist predators suffer population crashes when seed crops fluctuate ( 8 , 14 , 15 ), and even specialist predators are susceptible to satiation during mast years ( 30 , 58 , 59 ). Furthermore, masting plants can be synchronized over hundreds or even thousands of kilometers ( 60 , 61 ).…”

Masting increases seedling recruitment near and far: Predator satiation and improved dispersal in a fleshy‐fruited tree

“…80%–90% to c . 20%–30% (Bogdziewicz et al, 2021; Seget, Bogdziewicz, Holeksa, Ledwoń, Milne‐Rostkowska, et al, 2022; Żywiec et al, 2013). In the light of this past evidence, we believe that the higher proportion of fruits recruited under rowan trees after mast years was a result of starvation of seed predators.…”

“…Moreover, insect predation exerts a selection pressure towards masting by promoting more synchronised tree phenotypes (Bogdziewicz et al, 2021). Finally, an analysis of costs (elevated density‐dependent seedling mortality following pulsed recruitment) and benefits of masting indicated that masting improves fitness in rowan (Seget, Bogdziewicz, Holeksa, Ledwoń, Milne‐Rostkowska, et al, 2022).…”