Special issue in honour of Prof. Reto J. Strasser - Seasonal variation and trade-off between frost resistance and photosynthetic performance in woody species

Abstract

We tested the seasonal variability of frost resistance and photosynthesis characteristics, namely net photosynthetic rate at saturating irradiance and ambient atmospheric CO2 concentrations, maximum carboxylation rate, and measurements based on the JIP-test, namely maximum quantum yield of PSII and the performance index. Additionally, we measured leaf functional traits, namely specific leaf area, leaf dry matter content, stomatal pore area index, and chlorophyll content. We assessed all traits weekly on two evergreen species Berberis vulgaris and Quercus × hispanica as well as the two summer green species Betula pendula and Quercus pubescens. We found that there was a high seasonal variability in all traits except stomatal pore area index. In a multivariate analysis, we could show trade-offs between growth rates and leaf thickness on the first axis, as well as resistance and performance on the second axis. The findings help understand ecophysiological processes and fine-tune biosphere models.

The timing of leaf senescence relates to flowering phenology and functional traits in 17 herbaceous species along elevational gradients

“…The analyses of leaf functional traits offer an excellent possibility to explain species-specific responses in phenology to changing abiotic conditions, which have been previously shown in the case of flowering phenology (Bucher, König, et al, 2018;Fitter & Fitter, 2002;König et al, 2018;Sun & Frelich, 2011). Looking at leaf senescence, we expect that high water-use efficiency and resistance to outside stressors are related to later leaf senescence, whereas higher growth rates and higher nitrogen values, that is, photosynthetic values, are related to earlier leaf senescence as there is a general trade-off between growth and resistance (Bucher, Feiler, et al, 2018;Gast et al, 2020).…”

“…At each census the percentage of each subpopulation showing leaf senescence, displayed either as dead leaves or visual colouring, was recorded. Thus, we detected the aspect of leaf senescence which is visually observable, not the decline of photosynthetic activity, which might have started much earlier than the colouring and abscission of the leaves (Gast et al, 2020;Holland et al, 2014).…”

“…Monitoring leaf senescence on a purely visual basis, however, could have yielded confounding results. For example, fluorescence measurements, that is, F v /F m , or the measurement of chlorophyll content offer the possibility to quantify senescence events from a biochemical perspective (Gast et al, 2020;Holland et al, 2014). Additional data on ecophysiological traits could be collected in future works to underpin these findings based on visual observations and to quantify senescence events better.…”

Foliar summer frost resistance measured via electrolyte leakage approach as related to plant distribution, community composition and plant traits

“…The percentage of electrolyte leakage (PEL) after exposure to a temperature stress is suggested to be a simple and inexpensive alternative technique to estimate frost tolerance in selected plant organs (FR PEL ; Gurvich et al., 2002, Pérez‐Harguindeguy et al., 2013, Gast et al., 2020). The method is based on the fact that freezing disrupts cell membranes resulting in electrolyte leakage, which can be easily assessed by measuring changes in conductivity of a solution bathing the tissue (Gurvich et al., 2002; Pérez‐Harguindeguy et al., 2013).…”

“…Yet, the published evidence on functional links between FR and other plant functional traits is limited to a very few studies (e.g. Bucher, Feiler, et al, 2018; Gast et al., 2020; Sierra‐Almeida et al., 2010), whereas in only one of them the FR PEL approach was used (Gast et al., 2020).…”