Changes in nutrient concentrations of leaves and roots in response to global change factors

Abstract

Global change impacts on biogeochemical cycles have been widely studied, but our understanding of whether the responses of plant elemental composition to global change drivers differ between above- and belowground plant organs remains incomplete. We conducted a meta-analysis of 201 reports including 1,687 observations of studies that have analyzed simultaneously N and P concentrations changes in leaves and roots in the same plants in response to drought, elevated [CO ], and N and P fertilization around the world, and contrasted the results within those obtained with a general database (838 reports and 14,772 observations) that analyzed the changes in N and P concentrations in leaves and/or roots of plants submitted to the commented global change drivers. At global level, elevated [CO ] decreased N concentrations in leaves and roots and decreased N:P ratio in roots but no in leaves, but was not related to P concentration changes. However, the response differed among vegetation types. In temperate forests, elevated [CO ] was related with lower N concentrations in leaves but not in roots, whereas in crops, the contrary patterns were observed. Elevated [CO ] decreased N concentrations in leaves and roots in tundra plants, whereas not clear relationships were observed in temperate grasslands. However, when elevated [CO ] and N fertilization coincided, leaves had lower N concentrations, whereas root had higher N concentrations suggesting that more nutrients will be allocated to roots to improve uptake of the soil resources not directly provided by the global change drivers. N fertilization and drought increased foliar and root N concentrations while the effects on P concentrations were less clear. The changes in N and P allocation to leaves and root, especially those occurring in opposite direction between them have the capacity to differentially affect above- and belowground ecosystem functions, such as litter mineralization and above- and belowground food webs.

Different Responses and Links of N:P Ratio Among Ecosystem Components Under Nutrient Addition in a Temperate Forest

“…Consistent with our hypothesis, our result showed a greater response of leaf than root to nutrient addition in their P concentration and N:P ratio, which is supported by a few of previous studies (Fernando et al, ). However, this result is different with most previous studies reporting that leaf has a stronger N:P homeostatic control than root under changing environments (Cernusak et al, ; Liu et al, ; Sardans et al, ). The difference of our result from these studies may be due to a change from belowground competition for root nutrient uptake to aboveground light competition for photosynthesis in this ecosystem (Lan & Bai, ).…”

“…This study distinguishes from previous studies in two aspects. First, unlike previous experiments examining stoichiometric variations for one or some of ecosystem components separately (Sardans et al, ; Sardans et al, ; Zhang et al, ), we explored ecosystem stoichiometric response to nutrient enrichment in a whole system view and found different stoichiometric responses of multiple ecosystem components to nutrient addition. Second, we systematically revealed stoichiometric relationships among diverse ecosystem components in the context of nutrient enrichment.…”

Responses of Foliar Nutrient Status and Stoichiometry to Nitrogen Addition in Different Ecosystems: A Meta‐analysis

“…Nitrogen addition significantly decreased foliar P, K, Ca, and Mg but significantly increased foliar N and Al across all biomes (Figure a), indicating that N addition influences plant nutrient status. Changes in N, P, and N:P are the basis for understanding the effects of N addition on nutrients and have been studied extensively in both manipulative experiments (Huang et al, ; Lü et al, ) and reviews (Sardans et al, ; You et al, ; Yue et al, ). The results of the present study, showing a significant increase in N (20.18%) and a decrease in P concentrations (2.40%), are consistent with those of previous meta‐analyses (You et al, ; Yuan & Chen, ).…”

Nutrient addition affects scaling relationship of leaf nitrogen to phosphorus in Arabidopsis thaliana

“…Thus, N addition promoted the growth dilution effect together with little enhancement of P uptake capacity, resulting in the decreasing leaf P concentration (Deng et al, ; Li et al, ). Contrastingly, P addition enhanced the N‐uptake capacity more than can be normally matched by the growth dilution effect, resulting in an increase in the leaf N concentration (Bracken et al, ; de Groot et al, ; Sardans et al, ).…”

“…When exploring the leaf N‐P scaling relationships, pooled data from all levels of N or P addition are used to calculate the scaling exponent from N or P addition, respectively. We hypothesize that scaling exponent from N addition is higher than that from P addition because N and P additions would increase their respective availability in soils and concentration in plant tissues but may raise the likelihood of each other's limitation (Deng et al, ; Li et al, ; Sardans et al, ; Yan, Tian, Han, Tang, & Fang, ; Yuan & Chen, ; Zhang et al, ). Accordingly, compared with P addition, N addition could cause a relatively higher variability in leaf N concentrations but a relatively lower variability in leaf P concentrations, which would result in a higher scaling exponent.…”