Is the differential response of riparian plant performance to extreme drought and inundation events related to differences in intraspecific trait variation?

Previous research on the impacts of extreme events has focussed mainly on plant performance. Selective effects of extremes suggests that appropriate traits to withstand extremes, or the ability to modulate traits, may increase the competitive advantage and survival of a species. We tested how multiple extreme events affect riparian plant performance, and whether this relates to intraspecific trait variation. We hypothesised that species tolerant to extreme environmental conditions would show highest intraspecific trait variation. We conducted a greenhouse experiment where 25 wet to drought-tolerant species (grasses and herbs) were subjected to single and double 10 day drought and inundation events, and all combinations thereof. We measured plant performance and multiple traits. Performance was severely reduced, with clear synergistic, non-additive effects of extreme events. Adverse effects were stronger for wet-tolerant than drought-tolerant species and for grasses than herbs. Three traits were identified as predictors of species responses to extremes. Despite known trait variation for these species, no variation occurred under these conditions, indicating that responses are difficult to explain from impacts of mean environmental conditions. Our results indicate that multiple events may lead to quantitatively different impacts than single events, which hampers predicting plant response to a future climate.

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A willow drawing from 1786: the earliest depiction of intraspecific trait variation in plants?

Annals of Botany ◽

10.1093/aob/mcaa091 ◽

2020 ◽

Author(s):

Ulrich E Stegmann

Keyword(s):

Environmental Conditions ◽

18Th Century ◽

Elevation Gradient ◽

Experimental Studies ◽

Fourth Century ◽

Trait Variation ◽

Intraspecific Trait Variation ◽

Bavarian Alps ◽

In The Wild ◽

Unidentified Species

Abstract Background and Aims The study of intraspecific trait variation (ITV) in plants has a long history, dating back to the fourth century BC. Its existence was widely acknowledged by the end of the 18th century, although systematic and experimental studies commenced only a century later. However, the historiography of ITV has many gaps, especially with regard to early observations and visual documents. This note identifies an early depiction of plant ITV. Methods The botanical works of Johann Wolfgang von Goethe (1749–1832), a German writer and naturalist, were subjected to close reading. This included all publications and unpublished sources related to botany between 1785 and 1832 (e.g. notes, drafts, diaries, letters, drawings). This material is accessible in the multi-volume historical-critical edition of Goethe’s studies in natural science (Leopoldina-Ausgabe). Key Results A diary entry from 9 September 1786 described changes in leaf morphology along an elevation gradient in the Bavarian Alps. The leaves of an unidentified species of willow (Spix sp.) and gentian (Gentiana sp.) were said to become narrower with increasing elevation; leaves also stood further apart on twigs, and the latter became thinner. A crude drawing of two willow twigs illustrated the differences. Goethe conjectured that the differences were due to environmental conditions. Conclusions Goethe’s notes were anecdotal, and it is unclear whether the observed plant individuals actually belonged to the same species. Nevertheless, the notes represent an early and clear articulation of the hypothesis that changes in environmental conditions can cause ITV in a natural plant population. The drawing may be the earliest visual record of environmentally caused plant ITV in the wild.

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