Global effects of soil and climate on leaf photosynthetic traits and rates

Abstract

AimThe influence of soil properties on photosynthetic traits in higher plants is poorly quantified in comparison with that of climate. We address this situation by quantifying the unique and joint contributions to global leaf-trait variation from soils and climate.Location Terrestrial ecosystems world-wide.Methods Using a trait dataset comprising 1509 species from 288 sites, with climate and soil data derived from global datasets, we quantified the effects of 20 soil and 26 climate variables on light-saturated photosynthetic rate (Aarea), stomatal conductance (gs), leaf nitrogen and phosphorus (Narea and Parea) and specific leaf area (SLA) using mixed regression models and multivariate analyses.Results Soil variables were stronger predictors of leaf traits than climatic variables, except for SLA. On average, Narea, Parea and Aarea increased and SLA decreased with increasing soil pH and with increasing site aridity. gs declined and Parea increased with soil available P (Pavail). Narea was unrelated to total soil N. Joint effects of soil and climate dominated over their unique effects on Narea and Parea, while unique effects of soils dominated for Aarea and gs. Path analysis indicated that variation in Aarea reflected the combined independent influences of Narea and gs, the former promoted by high pH and aridity and the latter by low Pavail.Main conclusions Three environmental variables were key for explaining variation in leaf traits: soil pH and Pavail, and the climatic moisture index (the ratio of precipitation to potential evapotranspiration). Although the reliability of global soil datasets lags behind that of climate datasets, our results nonetheless provide compelling evidence that both can be jointly used in broad-scale analyses, and that effects uniquely attributable to soil properties are important determinants of leaf photosynthetic traits and rates. A significant future challenge is to better disentangle the covarying physiological, ecological and evolutionary mechanisms that underpin trait-environment relationships.

Gap-filling a spatially explicit plant trait database: comparing imputation methods and different levels of environmental information

“…4), despite the fact that phenological variation has been reported for some foliar traits ; but see Fajardo and Siefert, 2016). Lithology did not appreciably improve MICE imputations, in contrast to the reported influence of soil pH on some foliar traits (Maire et al, 2015;Simpson et al, 2016).…”

Improved representation of plant functional types and physiology in the Joint UK Land Environment Simulator (JULES v4.2) using plant trait information

“…2) and photosynthetic capacity can depend on the time of year. Recent work relating photosynthetic capacity to climate variables, environmental factors, and soil conditions shows promise for better capturing the dynamic nature of this parameter (e.g., Verheijen et al, 2013;Ali et al, 2015;Maire et al, 2015).…”

Grass strategies and grassland community responses to environmental drivers: a review

“…At the global scale, it has been recently shown that strategies of nitrogen and water acquisition are independent. They co-vary with independent soil dimensions (soil pH and soil available phosphorus) and they both lead to increased leaf photosynthetic rate (Maire et al 2015, but see Reich 2014 defining water-nitrogen strategies at a local scale). How each resource is linked with a specific strategy of resource capture is a further step to investigate in order to better predict the interactive effects of multiple resource gradients.…”

“…Considering the independent dimensions of environment will also help to better understand the different selection forces for plant functional traits. For instance, leaf nitrogen content increases both with soil fertility and climatic aridity (Maire et al 2015). In grasslands, the herbivory pressure and the management can be considered as additional dimensions of the environment to which species will respond.…”