Concentration of sugars, phenolic acids, and amino acids in forest soils exposed to elevated atmospheric CO2 and O3

Abstract

Concentrations of soluble soil sugars, soluble phenolic acids, and free amino acids were measured in three forest communities at the FACTS-II Aspen FACE Site near Rhinelander, WI, in order to better understand how elevated atmospheric CO 2 and O 3 are influencing soil nutrient availability and cycling. Sugars, phenolic acids, and amino acids are mostly derived from plant and microbial processes, and have the potential to be influenced by changes in carbon inputs. We hypothesized that concentrations in the soil would parallel increases seen in biological activity, due to greater net primary productivity under elevated CO 2 and seasonal patterns of root growth. Chemical analysis of soils revealed marginally significant increases of total soluble sugars and total soluble phenolic acids in the elevated CO 2 treatment (+27 mg kg À1 , +0.02 mmol g À1 ), but there were no significant differences in concentrations due to elevated O 3 or CO 2 +O 3 . Total free amino acid concentrations were not affected by any of the treatments, but significant shifts in individual amino acids were observed. Elevated CO 2 and the interaction treatment (elevated CO 2 +O 3 ) increased aspartic acid concentrations, while elevated O 3 treatment decreased the concentration of valine. Concentrations of sugars increased throughout the growing season, while phenolic acids were constant and amino acids decreased. The birch-aspen community had the highest concentration of phenolic acids and sugars overall, while maple-aspen had the lowest. These findings suggest that concentrations of soluble sugars, soluble phenolic acids, and free amino acids in the soil are strongly influenced by soil properties, plant and microbial activity, plant community composition, and to a lesser degree, changes in atmospheric CO 2 and O 3 .

Soil amino-acid availability across a temperate-forest fertility gradient

“…Other researchers have noted a similar decline in free amino acid concentrations from spring to summer in both arctic tundra (Weintraub and Schimel 2005) and a young sub-boreal forest in Wisconsin (Johnson and Pregitzer 2007). In both studies the authors attributed the decline in free amino acid pools to increased N demand by plants and microorganisms in the heart of the growing season, which is consistent with my results where the transition from high to low pool sizes generally coincides with timing of canopy leaf out in these deciduous forests.…”

Elevated atmospheric CO2 affected photosynthetic products in wheat seedlings and biological activity in rhizosphere soil under cadmium stress

“…However, elevated atmospheric CO 2 and Cd contamination of soil are concurrent environmental problems, and it is important to investigate their combined effects on plant photosynthetic products, soil biological activity, and organic compounds in rhizosphere soils. Many studies have reported the effects of either elevated CO 2 or metal contamination on these variables (Johnson and Pregitzer 2007;KwonRae et al 2007), but little is known about their combined effects, especially in crop plants. We examined these effects in wheat, a crop that forms an important part of the human diet worldwide (H gy et al 2009).…”

“…Soil AN concentration was determined by persulfate digestion (Sollins et al 1999). Total soluble sugars were extracted according to Johnson and Pregitzer (2007) and measured using phenolsulfuric acid colorimetry (Dubois et al 1956). Total free amino acid concentrations were measured using the ninhydrin colorimetric method (Moore and Stein 1954), total soluble phenolic acid content was analyzed using the FolinCiocalteu method (DeForest et al 2005), and total organic acid content was measured by spectrophotometry with FeCl 3 (Liu and Mo 1985).…”

“…These effects include increased growth rates and productivity or altered biomass allocation patterns, mainly as a result of stimulation of photosynthesis (Bunce 2004;Marchi et al 2004;Kim and Kang 2011). Large fluxes of primary and secondary compounds into soil have been observed under elevated CO 2 (Johnson and Pregitzer 2007), resulting in increased levels of dissolved organic carbon (DOC), total soluble sugars, and soluble phenolic acids in soil (Freeman et al 2004), which, in turn, could affect the activity and survival of soil microorganisms. In addition, elevated atmospheric CO 2 has been associated with increased microbial biomass and soil enzyme activity, such as that of urease, protease, invertase, xylanase, arylsulfatase, and alkaline phosphatase (Kandeler et al 2006;Li et al 2010).…”

Chemical and anatomical changes in Liquidambar styraciflua L. xylem after long term exposure to elevated CO2

“…Nutrient balance is also important for differentiation of photosynthate, yet several studies showed no significant differences in the amount of total extractives with elevated CO 2 treatment, although the concentration of proteins and mineral nutrients decreased and the lipid compositions were altered (DaMatta et al, 2010;Kilpelainen et al, 2005Kilpelainen et al, , 2003. Phenolic compounds of plants grown under elevated CO 2 condition have been also studied (Ghasemzadeh et al, 2010;Johnson and Pregitzer, 2007;Penuelas et al, 1996). Nonstructural sugars and starch content of CO 2 enriched xylem from several forest FACE sites increased by 30e40 % compared to the control samples (Ainsworth and Long, 2005).…”