When and where soil is important to modify the carbon and water economy of leaves

Abstract

Summary Photosynthetic ‘least‐cost’ theory posits that the optimal trait combination for a given environment is that where the summed costs of photosynthetic water and nutrient acquisition/use are minimised. The effects of soil water and nutrient availability on photosynthesis should be stronger as climate‐related costs for both resources increase. Two independent datasets of photosynthetic traits, Globamax (1509 species, 288 sites) and Glob13C (3645 species, 594 sites), were used to quantify biophysical and biochemical limitations of photosynthesis and the key variable Ci/Ca (CO2 drawdown during photosynthesis). Climate and soil variables were associated with both datasets. The biochemical photosynthetic capacity was higher on alkaline soils. This effect was strongest at more arid sites, where water unit‐costs are presumably higher. Higher values of soil silt and depth increased Ci/Ca, likely by providing greater H2O supply, alleviating biophysical photosynthetic limitation when soil water is scarce. Climate is important in controlling the optimal balance of H2O and N costs for photosynthesis, but soil properties change these costs, both directly and indirectly. In total, soil properties modify the climate‐demand driven predictions of Ci/Ca by up to 30% at a global scale.

Invasion‐induced root–fungal disruptions alter plant water and nitrogen economies

“…Specifically, plants in the ambient treatment adopted a resource conservative strategy (low nitrogen concentration and specific leaf area) 9 . We also find evidence that plants in the Alliaria ambient treatment had a higher cost of nitrogen uptake than plants in the Alliaria weeded treatment, as indicated by the greater PNUE and lower ratio of N area to g s , consistent with previous results across nutrient availability gradients 32 . For one native species, Arisaema, there was evidence of differential trait investment that increased PNUE and decreased WUE, as would be expected if nutrient availability was more impacted than water availability by Alliaria invasion (Figure 2) 30 .…”

“…We also found that plants in the ambient treatment adopted a resource conservative strategy (reduced specific leaf area) (Funk 2013). Together, these results are consistent with previous plant physiology responses across nutrient availability gradients (Paillassa et al 2020), and support, for the first time, the hypothesis that invasion-induced changes in native plant traits are generated by mutualism disruption and reduced soil resource provisioning. In other words, because of the reduction in nutrient availability by Alliaria, native plants in these plots are increasing their relative water use to maintain photosynthesis at lower relative nutrient use.…”

“…We expect the optimal combination of photosynthetic traits to shift if invasive species alter the availability or provisioning of one or more soil resources. In this scenario, native plants in the invaded community that are best able to shift their morphological, anatomical and physiological traits are likely to be more tolerant to invasion (Wright et al 2003;Paillassa et al 2020).…”

Invasion-induced root-fungal disruptions alter plant water and nitrogen economies

“…Specifically, plants in the ambient treatment adopted a resource conservative strategy (low nitrogen concentration and specific leaf area) 9 . We also find evidence that plants in the Alliaria ambient treatment had a higher cost of nitrogen uptake than plants in the Alliaria weeded treatment, as indicated by the greater PNUE and lower ratio of N area to g s , consistent with previous results across nutrient availability gradients 32 . For one native species, Arisaema, there was evidence of differential trait investment that increased PNUE and decreased WUE, as would be expected if nutrient availability was more impacted than water availability by Alliaria invasion (Figure 2) 30 .…”

Photosynthetic and Morphological Acclimation to High and Low Light Environments in Petasites japonicus subsp. giganteus

“…Third, the diurnal course of the photosynthetic rate depends not only on light but also on other environmental factors (i.e., humidity, temperature, VPD, etc.) [42,109,110] in addition to whole-plant water availability [4,[111][112][113][114][115]. Therefore, the effect of midday depression due to stomatal closure [60,110,112,115] and photoinhibition [60,112] also would significantly alter the daily carbon gain of leaves.…”