In situ warming in the Antarctic: effects on growth and photosynthesis in Antarctic vascular plants

Abstract

The Antarctic Peninsula has experienced a rapid warming in the last decades. Although recent climatic evidence supports a new tendency towards stabilization of temperatures, the impacts on the biosphere, and specifically on Antarctic plant species, remain unclear. We evaluated the in situ warming effects on photosynthesis, including the underlying diffusive, biochemical and anatomical determinants, and the relative growth of two Antarctic vascular species, Colobanthus quitensis and Deschampsia antarctica, using open top chambers (OTCs) and gas exchange measurements in the field. In C. quitensis, the photosynthetic response to warming relied on specific adjustments in the anatomical determinants of the leaf CO transfer, which enhanced mesophyll conductance and photosynthetic assimilation, thereby promoting higher leaf carbon gain and plant growth. These changes were accompanied by alterations in the leaf chemical composition. By contrast, D. antarctica showed no response to warming, with a lack of significant differences between plants grown inside OTCs and plants grown in the open field. Overall, the present results are the first reporting a contrasting effect of in situ warming on photosynthesis and its underlying determinants, of the two unique Antarctic vascular plant species, which could have direct consequences on their ecological success under future climate conditions.

Effects of climate warming on Sphagnum photosynthesis in peatlands depend on peat moisture and species‐specific anatomical traits

“…We found that the etiolation of warmed S. medium capitula seemed to have hampered its ability to increase its photosynthesis. The shrinkage of capitula may have triggered specific adjustments in the leaf anatomical determinants of CO 2 fixation and/or transfer (Sáez, Cavieres, & Galmés, ), limiting photosynthetic CO 2 assimilation of S. medium under higher temperatures. Ultimately, although the exact mechanisms are unclear, our results suggest that S. medium has a lower phenotypic and functional plasticity than S. fallax and as such is unable to adapt its morphology to cope with rising temperatures.…”

Contrasting thermal acclimation of leaf dark respiration and photosynthesis of Antarctic vascular plant species exposed to nocturnal warming

“…Recent publications have reported that both Antarctic species respond differentially to the in situ diurnal warming (Sáez et al ). Nevertheless, to the best of our knowledge, our study is the first one analyzing the effect of nocturnal warming on respiration and photosynthesis in both Antarctic vascular species.…”

“…Leaf temperature records taken in this study site during the summer showed that in both species leaf temperature during the day is on average 5 to 8°C, with a maximum of ca. 10°C, and decreasing to 0 to 2°C during the night (Sáez et al ).…”

“…Plant response to increasing temperature has become a major concern, because some species cannot adapt to the new climate regimes, leading to widespread die‐offs and/or range shifts (Gunderson et al , Hikosaka , Sage et al ). While most of the studies about the consequences of climate change on plants have focused on the effect of diurnal temperature increases (Day et al , Leakey et al , Sáez et al ), historical meteorological records and model projections have revealed that warming occurred asymmetrically with a faster rise in daily minimum temperatures (i.e. night) compared with daily maximum temperatures (i.e.…”

How do vascular plants perform photosynthesis in extreme environments? An integrative ecophysiological and biochemical story

“…The only two native vascular plants of Antarctica (Figure c) have been extensively studied in terms of temperature, water availability and nutrient deficiency (Sáez et al , , ,b; Clemente‐Moreno et al , , ). Interestingly, for both species, g m is the most important limitation under low temperature, drought and nutrient deficiency, as has been previously reported for species from semiarid‐arid environments (Galmés et al , ).…”