Abstract
Relationships between age, time of emergence, and leaf traits of individuals were investigated in a population of Erythroniumdens-canis L. in a hilly woodland area named Farneto-C, near Bologna, Italy. In 2015, 591 individuals were counted, 19 of which were flowering (FLO), 442 were mature non-flowering (MNF) and 130 were juveniles (JUV). FLO emerged at the end of February, whereas most MNF and JUV appeared at the middle and end of March, respectively. The mean aboveground survivorship of MNF was 24 days. Most MNF had large, oval to shield-shaped leaves with red-brown mottling, whereas most JUV leaves were smaller, usually oblong or lanceolate with a rough maculation or none. These results suggest that both timing of emergence and leaf shape are related to the age of the bulb. Based on leaf background, plants were classified into three major types with a likely genetic basis in the 2015 and 2016 surveys (the latter limited to FLO): a dominant silvery type (SLV, 62–74%), silvery-and-green type (S&G, 23–32%), and a less frequent vivid-green type (GRN, 3–5%). Several subtypes were also identified, but only one was dominant within each type. The three basic patterns appear to be phenotypically stable and no differences between MNF and FLO were found; once the juvenile stage has passed, each plant produces the same leaf type year after year. In addition, our results on the discoloration time-course of red-brown spots suggest that the functional role of leaf mottling is not related to pollinator attraction. Instead, leaf mottling could play a role in camouflage against herbivores.The observed massive grazing on flowers, more than leaves, could explain why the frequency of mature individuals was biased towards the non-flowering ones.
Highlights
The numerous American Erythronium species have life cycles that are quite different between high-mountain and forest taxa, but all are strictly connected with snow and snowmelt (Vézina and Grandtner 1965, Lapointe 2001, Yamagishi et al 2005), so these plants are exposed to the effects of climate change
We aimed to answer the following questions: 1) Is there any relationship between age and time of emergence of individuals? 2) Are leaf shape and leaf mottling related to the phenological stage of individuals? 3) What is the functional role of mottling in the species? By answering these questions, we can provide insight into the relationships between individual leaf traits and population structure and dynamics in E. dens-canis
We investigated the discoloration of spots as a further descriptor and we detected the following classes: red-brown spots, partially depigmented spots, and wholly green-discolored spots
Summary
Spring ephemerals can be considered as model species for addressing plant responses to environmental changes (Lapointe 2001), especially since climate change has become a major issue for ecologists and conservationists (e.g. Dormann and Woodin 2002, Totland and Alatalo 2002, Parmesan 2006, Pfeifer et al 2006, De Frenne et al 2011, Marchin et al 2014). All Erythronium species are bulbous geophytes with the phenological characteristics of spring ephemerals (Schemske et al 1978, Lapointe 2001).They play a relevant role in some forest ecosystems due to their high biomass and effectiveness in preserving soil nutrients (Muller and Bormann 1976, Muller 1978) This genus is distributed in the northern hemisphere with five Eurasian species (Bartha et al 2015) and about 24 species in North America (Mathew 1992, Allen and Robertson 2002, Allen et al 2003). For the Japanese species E. japonicum, too, several contributions have been devoted to the phenological and ecophysiological responses to temperature variation in seeds, bulbs, and leaves (Yoshie and Fukuda 1994, Sawada et al 1997, Kondo et al 2002)
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