Effects of two root-secreted phenolic compounds from a subalpine coniferous species on soil enzyme activity and microbial biomass

Abstract

(2015) Effects of two root-secreted phenolic compounds from a subalpine coniferous species on soil enzyme activity and microbial biomass, Chemistry and Ecology, 31:7, 636-649, DOI: 10.1080/02757540.2015 In order to evaluate the ecological consequences and potential mechanisms of specific C compounds on soil microbial processes under climate warming, we injected solutions of two modelled root exudates, 2,6-di-tert-butyl-4-methylphenol (BHT) and 1,2-benzenedicarboxylic acid, dibutyl ester (DBP), respectively, into soil at two concentrations (20 and 1000 µg g −1 soil). For all treatments, soils amended with the two phenolic compounds were incubated at two temperatures (20°C and 30°C) for 30 days. The responses of soil enzyme activity and microbial property to modelled root exudates to some extent depended on temperature regime, exudation component, and addition concentration. For example, the addition of BHT tended to decrease the soil enzyme activities. However, DBP addition generally increased the two metabolic enzyme activities at 30°C, and tended to decrease the two enzyme activities at 20°C, but a significant reduction was observed only at a high concentration at 20°C. The microbial biomass and enzyme activity were generally lower at 30°C compared to those at 20°C, when averaged across all treatment combinations. Taken together, our results indicated that the amounts and quality of liable root-derived C can differentially affect microbial processes, and various environmental changes will greatly complicate root-microbe-soil interactions in forests.

Do Silvi-Medicinal Plantations Affect Tree Litter Decomposition and Nutrient Mineralization?

“…Considering the simultaneous acceleration of the decomposition, these inhibitory effects might be attributed to the C-utilizing decomposer bloom consuming a mass of N and P, leading to N and P immobilization from the soil. In this study, the activities of protease and phosphatase were rarely affected by PSMs relative to C-consuming enzymes, which was contrary to the results of previous studies [14,16,22]. This might be because the microbes were forced to secrete these enzymes to obtain sufficient nutrients, consequently covering the decreases in enzymatic activities.…”

“…They were also found to be antifeedants to soil fauna [14,15]. Phenolic substances and their derivatives can selectively hinder the growth of certain microbial species and decrease their diversity and carbon metabolism ability [16][17][18]. Some flavone substances also exhibit inhibitory effects on the growth of fungi [19].…”

“…Hence, in view of the abundant secondary metabolites in medicinal herbs, the components leached by precipitation might hinder the decomposition of litter by inhibiting the activities of microbes and enzymes and, consequently, the long-term stability of forest ecosystems. In the existing literature, many researchers have reported the inhibitory effects of plant secondary metabolites (PSMs) on litter decomposition; however, most of them addressed only the effects of endogenous PSMs [20,21] or the effects of one or several types of artificially added PSMs [14,16,[22][23][24]. The effects of PSMs from living plants, especially those that are leached by natural precipitation, with a low concentration and complex components, remain less well understood.…”

Invasion by Fallopia japonica alters soil food webs through secondary metabolites

“…This hypothesis 371 was based on the literature which frequently mentions release of secondary metabolites in 372 the environment by knotweeds as a major contributor to knotweed effects in their invasive 373 range(Vastano et al, 2000). Other lab studies have shown concentration-dependent effects 374 of some root-secreted phenolic compounds on microbial biomass (e.g Zhang et al, 2015)…”

Impacts of wise grazing on physicochemical and biological features of soil in a sandy grassland on the Tibetan Plateau

“…Then, total (TC) and total nitrogen (TN) were determined with 1 g of sample using a vario MACRO cube CN Elemental analyzer (Elementar Analysensysteme, Langenselbold Germany) (Wang, Wu, Zhou, Bing, & Sun, ). Soil organic carbon (SOC) was determined after removal of inorganic carbon by 1 mol/L HCl (Kelly & Burke, ; Zhang et al, ). Total phosphorus (TP) was performed using the modified Hedley sequential extraction method (Tiessen & Moir, ) by digesting 500 mg of sample with 7:1 HNO 3 :HClO 4 for 4 hr at 180°C.…”