We used long-term datasets to analyse (1) the patterns of covariation between basic climatic variables (temperature and rainfall) and the timing of reproduction and reproductive success; and (2) long-term trends in both reproductive param

Plants use their roots to forage for nutrients in heterogeneous soil environments, but different plant species vastly differ in the intensity of foraging they perform. This diversity suggests the existence of constraints on foraging at the species level. We therefore examined the relationships between the intensity of root foraging and plant body traits across species in order to estimate the degree of coordination between plant body traits and root foraging as a form of plant behavior. We cultivated 37 perennial herbaceous Central European species from open terrestrial habitats in pots with three different spatial gradients of nutrient availability (steep, shallow, and no gradient). We assessed the intensity of foraging as differences in root placement inside pots with and without a spatial gradient of resource supply. For the same set of species, we retrieved data about body traits from available databases: maximum height at maturity, mean area of leaf, specific leaf area, shoot lifespan, ability to self-propagate clonally, maximal lateral spread (in clonal plants only), realized vegetative growth in cultivation, and realized seed regeneration in cultivation. Clonal plants and plants with extensive vegetative growth showed considerably weaker foraging than their non-clonal or slow-growing counterparts. There was no phylogenetic signal in the amount of expressed root foraging intensity. Since clonal plants foraged less than non-clonals and foraging intensity did not seem to be correlated with species phylogeny, we hypothesize that clonal growth itself (i.e., the ability to develop at least partly self-sustaining ramets) may be an answer to soil heterogeneity. Whereas unitary plants use roots as organs specialized for both resource acquisition and transport to overcome spatial heterogeneity in resource supply, clonal plants separate these two functions. Becoming a clonal plant allows higher specialization at the organ level, since a typical clonal plant can be viewed as a network of self-sustainable harvesting units connected together with specialized high-throughput connection organs. This may be an effective alternative for coping with spatial heterogeneity in resource availability.

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.

Whole genome duplication is a key process in plant evolution and has direct phenotypic consequences. However, it remains unclear whether ploidy-related phenotypic changes can significantly alter the fitness of polyploids in nature and thus contribute to establishment of new polyploid mutants in diploid populations. We addressed this question using a unique natural system encompassing a diploid and its sympatric locally established autotetraploid derivative. By setting a common garden experiment with two manipulated environmental factors (presence/absence of serpentine substrate and competition), we tested whether these two locally important factors differently shape the phenotypic response of the two ploidy levels. Tetraploids attained significantly higher values of both above- and below-ground biomass, and root : shoot ratio compared to their diploid progenitors. Tetraploid superiority in vegetative fitness indicators was most prominent when they were cultivated together with a competitor in nutrient-rich nonserpentine substrate. We show that even genetically very closely related diploids and tetraploids can respond differently to key environmental factors. Provided there are sufficient nutrients, tetraploids can be more successful in tolerating interspecific competition than their diploid progenitors. Such superior performance might have provided an adaptive advantage for the newly established tetraploid promoting colonisation of new (micro-)habitats, which was indeed observed at the natural site.

Orchids are distributed around the world, however, the factors shaping their specific distribution and habitat preferences are largely unknown. Moreover, many orchids are at risk of becoming threatened as landscapes change, sometimes declining without apparent reason. One important factor affecting plant distribution is nutrient levels in the environment. Nitrates can inhibit not only orchid growth and persistence, but also seed germination. We used in vitro axenic cultures to exactly determine the germination sensitivity of seven orchid species to nitrates and correlated this with soil properties of the natural sites and with the species’ habitat preferences. We found high variation in response to nitrate between species. Orchids from oligotrophic habitats were highly sensitive, while orchids from more eutrophic habitats were almost insensitive. Sensitivity to nitrate was also associated with soil parameters that indicated a higher nitrification rate. Our results indicate that nitrate can affect orchid distribution via direct inhibition of seed germination. Nitrate levels in soils are increasing rapidly due to intensification of agricultural processes and concurrent soil pollution, and we propose this increase could cause a decline in some orchid species.