Changes in the structural composition and reactivity of Acer rubrum leaf litter tannins exposed to warming and altered precipitation: climatic stress‐induced tannins are more reactive

Abstract

Summary Climate change could increase the frequency with which plants experience abiotic stresses, leading to changes in their metabolic pathways. These stresses may induce the production of compounds that are structurally and biologically different from constitutive compounds. We studied how warming and altered precipitation affected the composition, structure, and biological reactivity of leaf litter tannins in Acer rubrum at the Boston‐Area Climate Experiment, in Massachusetts, USA. Warmer and drier climatic conditions led to higher concentrations of protective compounds, including flavonoids and cutin. The abundance and structure of leaf tannins also responded consistently to climatic treatments. Drought and warming in combination doubled the concentration of total tannins, which reached 30% of leaf‐litter DW. This treatment also produced condensed tannins with lower polymerization and a greater proportion of procyanidin units, which in turn reduced sequestration of tannins by litter fiber. Furthermore, because of the structural flexibility of these tannins, litter from this treatment exhibited five times more enzyme (β‐glucosidase) complexation capacity on a per‐weight basis. Warmer and wetter conditions decreased the amount of foliar condensed tannins. Our finding that warming and drought result in the production of highly reactive tannins is novel, and highly relevant to climate change research as these tannins, by immobilizing microbial enzymes, could slow litter decomposition and thus carbon and nutrient cycling in a warmer, drier world.

The responses of soil and rhizosphere respiration to simulated climatic changes vary by season

“…The BACE employs a factorial design, with precipitation treatments applied to main plots and warming treatments applied to subplots across three experimental blocks (36 plots in total; Tharayil et al 2011). The four warming treatments included unwarmed controls, and low, medium, and high warming levels, which warmed the plant canopy by a maximum of ;18, ;2.78, and 48C, respectively.…”

Litters of photosynthetically divergent grasses exhibit differential metabolic responses to warming and elevated CO2

“…The main and interactive effects of warming and CO 2 on ester-bound phenolics were analyzed using PROC MIXED. Extractable polar metabolite data, DRIFT spectroscopy and ester-bound phenolics data were analyzed via principal component analysis (PCA; Tharayil et al 2011). In all statistical analyses differences among individual treatments was determined using Tukey's HSD multicomparison test.…”

“…One such response is the alteration of metabolite profiles in plants exposed to climatic changes, as this response may potentially influence soil carbon storage by altering the chemistry of litter available for decomposition (Tharayil et al 2011). Although it is well known that the stress adaptation might alter plant metabolic pathways (Dixon and Paiva 1995, Guy et al 2008, Krasensky and Jonak 2012, most of the studies to date have primarily focused on capturing the compositional changes in metabolite-pools that are readily extractable, and less studied are the climate induced changes in non-extractable structural matrix of plant tissues that forms a major substrate for decomposition.…”

Application of biosurfactants for heavy netals leaching from immobilized activated sludge / Zastosowanie biosurfaktantów do wymywania metali ciężkich z immobilizowanego osadu czynnego

“…After lignins, tannins constitute the second, most frequent group of polyphenolic compounds occurring in vascular plants (Tharayil et al 2011). Their concentration depends on species and within a species on age and tissue type (Schweitzer et al 2008).…”