Environmental drivers and phylogenetic constraints of growth phenologies across a large set of herbaceous species

Abstract

Because perennial herbs of temperate climates develop their above‐ground parts every year anew, their success critically depends on the timing and speed of this growth (growth phenology). These parameters can play a role in species coexistence and may differ along environmental gradients. Still, we know little about them, as most phenological data come from observations of flowering and to a lesser degree leafing onset. We collected data on growth phenology of about 400 perennial herbs in a botanical garden to make the results independent of local differences in climatic drivers as much as possible. Using these data, we determined species‐specific parameters of Day of peak growth, Day of maturity and two types of growth rates associated with the change in plant size. Environmental conditions in which these species occur in the field were assessed using Ellenberg indicator values, which express species’ optima along gradients of moisture, nutrients and temperature. Both timing and speed of growth estimated in the common garden were affected by light and moisture conditions of the habitats where the species typically occur. All parameters showed phylogenetic conservatism. We identified two relationships among these parameters of growth phenology: (1) species with early peak growth had high relative growth rates in contrast to late species; (2) tall species showed later peak growth than short species. The first relationship is associated with survival under forest canopy, where species are selected to grow early and fast before trees leaf out, which restricts their size. The latter is associated with (asymmetric) competition for light in open habitats, where the main selection factor is for tall stature, which cannot be attained early in the season. Synthesis. We show that large differences in size growth dynamics among herbaceous species are constrained by a few key trade‐offs involving height at maturity, rate of growth and time when maximum height is attained. These trade‐offs correspond to major selective forces acting on herbaceous plants in temperate climates.

Tunicate bulb size variation in monocots explained by temperature and phenology

“…Within populations, larger plants produce flowers earlier and for longer durations, often have larger seeds, and produce a greater number of leaves, flowers, and fruits (Albert, Iriondo, Escudero, & Torres, ; Bustamante & Búrquez, ; Han, ; Marquis, ; McIntosh, ; Ollerton & Lack, ; Rees, , ; Susko & Lovett‐Doust, ). However, studies on interspecific variation show larger (i.e., taller) plants flower later relative to smaller plants (Huang, Koubek, Weiser, & Herben, ), suggesting different life‐history tradeoffs at different ecological scales. Therefore, investigations into the effects of size at different scales (e.g., within and among populations, between closely and distantly related groups, or cellular vs. morphological) can provide insights into the strategies that both small and large organisms adopt, and the subsequent ecological and evolutionary consequences of such changes.…”

“…number of leaves, flowers, and fruits (Albert, Iriondo, Escudero, & Torres, 2008;Bustamante & Búrquez, 2008;Han, 2001;Marquis, 1988;McIntosh, 2002;Ollerton & Lack, 1998;Rees, 1969Rees, , 1996Susko & Lovett-Doust, 2000). However, studies on interspecific variation show larger (i.e., taller) plants flower later relative to smaller plants (Huang, Koubek, Weiser, & Herben, 2018), suggesting different life-history tradeoffs at different ecological scales.…”

Temporal niche differentiation among species changes with habitat productivity and light conditions

“…From mid‐January to early August 2015, we measured plant foliage length (the stretched length of plant foliage from the ground to the tip of the topmost leaf) of each of the 381 species (six to eight healthy individuals of similar size for each plant species) every two weeks until plants reached maximum size. We chose foliage length as it can be reasonably assumed to be a good proxy of the plant's ability to compete for light, is well defined for most species, and it is correlated with other measures of plant size (Huang et al., ). Using the data on plant foliage length, we fitted the growth trajectory of each species by a simple logistic function of time, from which we extracted the day of peak growth (the day of year when the plant reached peak growth), absolute growth rate (cm/day, increment of plant foliage length per day at the day of peak growth) and standardized growth rate (1/day, percentage increment of plant foliage length per day at the day of peak growth) as parameters of growth phenology.…”

“…Here, we asked how species differ in their phenological patterns across different habitat types. First, we characterized a large set of species (381) by two major parameters of growth phenology, namely the day of peak growth and growth rates at that day (following Huang, Koubek, Weiser, & Herben, ; Sun & Frelich, ). We collected these data at one site (a botanical garden collection) to minimize effects of environmentally driven differences in growth phenology (see also Huang et al., ).…”

“…First, we characterized a large set of species (381) by two major parameters of growth phenology, namely the day of peak growth and growth rates at that day (following Huang, Koubek, Weiser, & Herben, ; Sun & Frelich, ). We collected these data at one site (a botanical garden collection) to minimize effects of environmentally driven differences in growth phenology (see also Huang et al., ). We were interested only in perennial species, as annual and woody species have very different growth strategies and their phenological parameters and growth rates cannot be easily compared with those of perennial herbs in one framework.…”