Altered leaf elemental composition with climate change is linked to reductions in photosynthesis, growth and survival in a semi‐arid shrubland

Abstract

1. Climate change will increase heat and drought stress in many dryland areas, which could reduce soil nutrient availability for plants and aggravate nutrient limitation of primary productivity. Any negative impacts of climate change on foliar nutrient contents would be expected to negatively affect the photosynthetic capacity, water use efficiency and overall fitness of dryland vegetation.2. We conducted a 4-year manipulative experiment using open top chambers and rainout shelters to assess the impacts of warming (~2°C, W), rainfall reduction (~30%, RR) and their combination (W + RR) on the nutrient status and ecophysiological performance of six native shrub species of contrasting phylogeny in a semi-arid ecosystem. Leaf nutrient status and gas exchange were assessed yearly, whereas biomass production and survival were measured at the end of the study.3. Warming (W and W + RR) advanced shoot growth phenology and reduced foliar macro-(N, P, K) and micronutrient (Cu, Fe, Zn) concentrations (by 8%-18% and 14%-56% respectively), net photosynthetic rate (32%), above-ground biomass production (28%-39%) and survival (23%-46%). Decreased photosynthesis and growth in W and W + RR plants were primarily linked to enhanced nutritional constraints on carbon fixation. Poor leaf nutrient status in W and W + RR plants partly decoupled carbon assimilation from water flux and led to drastic reductions in water use efficiency (WUEi; ~41%) across species. The RR treatment moderately decreased foliar macro-and micronutrients (6%-17%, except for Zn) and biomass production (22%). The interactive impacts of warming and rainfall reduction (W + RR treatment) on plant performance were generally smaller than expected from additive single-factor effects. 4. Synthesis. Large decreases in plant nutrient pool size and productivity combined with increased mortality during hotter droughts will reduce vegetation cover and nutrient retention capacity, thereby disrupting biogeochemical processes and accelerating dryland degradation with impending climate change. Increased macro-and micronutrient co-limitation of photosynthesis with forecasted climate change conditions may offset any gains in WUEi and productivity derived from | 49 Journal of Ecology LEÓN-SÁNCHEZ Et aL. S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: León-Sánchez L, Nicolás E, Prieto I, Nortes P, Maestre FT, Querejeta JI. Altered leaf elemental composition with climate change is linked to reductions in photosynthesis, growth and survival in a semi-arid shrubland. J

Simulated climate change decreases nutrient resorption from senescing leaves

“…Furthermore, we also found consistent reductions in mature and senesced leaf nutrient contents and changes in leaf stoichiometry across species in response to warming, which may further compromise the ability of dryland vegetation to endure drought stress under a warmer and drier climate (León‐Sánchez et al, , , ) and may interfere with trophic chains including plant interactions with herbivores, detritivores, and decomposers (Sardans, Peñuuelas, et al, ). For example, senesced leaf N and Ca are essential elements that stimulate litter decomposition rates and nutrient mineralization (Cornwell et al, ; Lovett, Arthur, & Crowley, ).…”

“…Given the key importance of this nutrient for plant physiological processes related to drought tolerance, for example, the maintenance of cellular turgor, stomatal and transpiration control, or the transport of plant photosynthetic assimilates (Sardans & Peñuelas, ), dryland plants are generally very efficient at resorbing this element from senescing leaves (Sardans, Peñuelas, & Rodà, ; Vergutz et al, ). In our experiment, warming strongly hampered foliar K resorption which, in combination with increasing drought stress (W+RR), the most plausible scenario for Mediterranean ecosystems in the future, could greatly reduce the ability of plants to tolerate future warmer and drier conditions (León‐Sánchez et al, , ). Since both N and K are essential nutrients that are nearly as limiting as P in arid and semiarid ecosystems (Hooper & Johnson, ; Sardans & Peñuelas, ), a reduction in foliar N and K resorption efficiencies with warming may reduce internal plant nutrient recycling and thus impose greater nutrient scavenging and uptake costs (Wright & Westoby, ).…”

Effect of drought and heat stresses on photosynthesis, pigments, and xanthophyll cycle in alfalfa (Medicago sativa L.)

“…Climate change will increase heat and drought stresses in many dryland areas, which could negatively affect the photosynthetic capacity. The interactive impacts of warming and rainfall reduction on plant performance were generally smaller than those expected from additive single-factor effects (León-Sánchez et al 2020). Drought and heat stresses significantly affected physiological and biochemical parameters of the examined grapevine cultivars (Tzortzakis et al 2020).…”

Warming Change Nutritional Status and Improve Stylosanthes capitata Vogel Growth Only Under Well-Watered Conditions

“…5a). Warming combined with drought has been previously reported to decrease nutrient content, which has been linked to decreased photosynthesis, water use efficiency, and dry biomass (León-Sánchez et al 2019). However, for leaf and Fig.…”