Simple measures of climate, soil properties and plant traits predict national‐scale grassland soil carbon stocks

Abstract

Soil carbon (C) storage is a key ecosystem service. Soil C stocks play a vital role in soil fertility and climate regulation, but the factors that control these stocks at regional and national scales are unknown, particularly when their composition and stability are considered. As a result, their mapping relies on either unreliable proxy measures or laborious direct measurements. Using data from an extensive national survey of English grasslands, we show that surface soil (0–7 cm) C stocks in size fractions of varying stability can be predicted at both regional and national scales from plant traits and simple measures of soil and climatic conditions. Soil C stocks in the largest pool, of intermediate particle size (50–250 μm), were best explained by mean annual temperature (MAT), soil pH and soil moisture content. The second largest C pool, highly stable physically and biochemically protected particles (0·45–50 μm), was explained by soil pH and the community abundance-weighted mean (CWM) leaf nitrogen (N) content, with the highest soil C stocks under N-rich vegetation. The C stock in the small active fraction (250–4000 μm) was explained by a wide range of variables: MAT, mean annual precipitation, mean growing season length, soil pH and CWM specific leaf area; stocks were higher under vegetation with thick and/or dense leaves. Testing the models describing these fractions against data from an independent English region indicated moderately strong correlation between predicted and actual values and no systematic bias, with the exception of the active fraction, for which predictions were inaccurate. Synthesis and applications. Validation indicates that readily available climate, soils and plant survey data can be effective in making local- to landscape-scale (1–100 000 km2) soil C stock predictions. Such predictions are a crucial component of effective management strategies to protect C stocks and enhance soil C sequestration

Impacts of 120 years of fertilizer addition on a temperate grassland ecosystem

“…We cannot be certain of the mechanism responsible for C accrual in these soils as FYM increases C input and buffers acidification simultaneously, making it difficult to evaluate their individual contribution. However, findings from a recent extensive landscape study suggests that soils with a higher pH within the observed range do not have greater SOC stocks [61]. While an increase in pH has previously been shown to positively influence SOC, including in the Park Grass experiment, results indicate that this is unlikely to occur at pH <6 [61, 62].…”

“…However, findings from a recent extensive landscape study suggests that soils with a higher pH within the observed range do not have greater SOC stocks [61]. While an increase in pH has previously been shown to positively influence SOC, including in the Park Grass experiment, results indicate that this is unlikely to occur at pH <6 [61, 62]. It appears more plausible that the positive effects of FYM addition on SOC stocks were due to increased C input via the direct addition of organic matter in FYM (Table 1).…”

Plant attributes explain the distribution of soil microbial communities in two contrasting regions of the globe

“…Sampling was conducted in March (2014). In England, soil samples were collected June–July 2005 from 180 sites covering the main grassland habitat classifications in the UK, namely acid, calcicolous, mesotrophic, and wet grasslands (de Vries et al ., ; Manning et al ., ). The survey covered a wide range of grassland communities within each habitat type and included a total of 256 grassland plant species, confirming the representative nature of the national survey (Rodwell, ).…”

Relationships between plant traits, soil properties and carbon fluxes differ between monocultures and mixed communities in temperate grassland

“…Furthermore, environmental gradients typically involve concomitant changes to both environmental factors and the plant community. This makes it difficult to tease apart plant community responses to the gradient from their effects on soil properties and ecosystem processes (Grigulis et al, ; Kichenin, Wardle, Peltzer, Morse, & Freschet, ; Legay et al, ; Manning et al, ; Sundqvist, Giesler, & Wardle, ). As such, our understanding of the importance of plant traits in driving soil properties and ecosystem functioning is limited to specific contexts.…”