Temporal and spatial trade-offs between resistance and performance traits in herbaceous plant species

Frost resistance (FR) is a highly adaptive trait and important for plant performance, survival and distribution. While overall seasonal changes in the frost resistance of herbaceous species are well documented, knowledge of the variability during the growth period is scarce. Responses could be expected due to differences in temperature yet investment in frost resistance might be at the expense of plant performance. To analyse temporal and spatial (i.e. same date but differing temperatures) variability, FR of leaves of six herbaceous species on five sampling dates were assessed along an elevational gradient in the northern limestone Alps. We used chlorophyll fluorescence techniques to calculate the lethal temperature of 90% of the population (LT90) thereof. To test the association with plant performance, we measured eco-morphological leaf traits (specific leaf area (SLA), leaf dry matter content, leaf phosphorous and magnesium content as well as stomatal pore area index (SPI)) in parallel. We found that FR as well as leaf traits exhibit a strong temporal variation whereas spatial variability was low. When analysing the relationship of FR to leaf traits we found that SLA as a proxy of growth rate was negatively associated with FR indicating a trade-off between growth and resistance, whereas SPI showed a positive relationship to FR. This finding gives further insight into the variability of traits and will help to improve predictions concerning plant performance and distribution under changing climate regimes.