The biological and physical stability and resilience of a selection of Scottish soils to stresses

Abstract

The ability of soil to resist and recover from anthropogenic and environmental stresses defines stability and resilience, respectively; an understanding of this ability is critical to sustainable land-use. In this study of 26 soils from across Scotland, we examine the influence of soil properties and antecedent conditions on physical and biological resilience to stress. The sites studied covered a wide range of soil types and land management, including serpentine soil from the Shetland Islands, a catena on the Highland Boundary Fault, and young aeolian sandy soils on the east coast. Biological resilience was measured as CO 2 evolution from soil with added plant residues after either a transient (heat) or a persistent (copper) stress. Measures of physical resilience were: (i) compression and expansion indices following rapid uniaxial compression (to 50 kPa) and relaxation; and (ii) void ratio changes due to an overburden stress and subsequent cycles of wetting and drying. Evolution of CO 2 from soil with added plant residues after heat or copper stress ranged from 23% to >100% that of the unperturbed soil, while the air-filled void ratio after the overburden stress ranged from 70% to >100% that of the unperturbed soil. Soils were grouped into quartiles based on their resistance to and recovery after each of the four prescribed stresses. Soil organic carbon (SOC) content correlated strongly with resilience after biological and physical stresses, particularly resistance to Cu stress (r ¼ 0.72) and recovery from compression (r ¼ 0.67), whereas there were no strong correlations between resilience following heat and any of the measured soil characteristics, although both land use and soil class were helpful in separating the responses. Resistance to compression was negatively correlated with SOC (r ¼ -0.63).

The effect of long-term soil management on the physical and biological resilience of a range of arable and grassland soils in England

“…For example, soil physical resilience has been expressed through monitoring pore volume (O'Sullivan et al, 1999;Zhang et al, 2005;Kuan et al, 2007) and strength (Munkholm and Schøjnning, 2004;Gregory et al, 2007) during and after compaction, by measuring the stability (Denef et al, 2001) and size distribution (Grant et al, 1995) of soil aggregates to wet-dry cycles, and by measuring vertical soil movements after compaction (Tobias et al, 2001). Biological resilience in soil has been quantified by measuring changes in the short-term mineralization of plant residues (Griffiths et al, 2000;Kuan et al, 2007), dissolved organic carbon , catabolic function (Degens and Harris, 1997) specific microbial function groups (Tobor-Kaplon et al, 2005;Wada and Toyota, 2007;Wertz et al, 2007) and the size and activity of the microbial biomass (Franco et al, 2004) in response to disturbance. Orwin and Wardle (2004) offer an interesting discussion on how to convert measured soil properties into resilience indices.…”

Functional and compositional responses in soil microbial communities along two metal pollution gradients: does the level of historical pollution affect resistance against secondary stress?

“…Firstly, investigated soils differed in (concentrations of) their initial stressors as well as various types of additional stressors; also, different microbial parameters were measured in the various studies. Secondly, soil properties may influence soil functioning (Kuan et al 2007) and microbial diversity may increase in response to stressors by enhancing the spatial and temporal heterogeneity of the soil environment, promoting species coexistence (Degens et al 2001;Fierer et al 2003). Thirdly, soils from different ecosystems and geographical settings may contain very different soil microbial communities, which are adapted to the local environment and may differ in their response to additional stressors (Fierer et al 2003).…”

Compressive behaviour of the soil in buffer zones under different management practices in Finland

“…McBride and Watson (1990) also observed the largest degree of rebound (0.018−0.075 g cm -3 ) upon stress removal (1.0 MPa) for structured unsaturated soil of the highest measured organic matter content and the lowest dry bulk density. Kuan et al (2007), on the other hand, noted that repacked soils in Scotland (0-31% clay) with the greatest organic carbon levels (1.7-30%) possessed poor resistance to but good recovery from compressive stress. This trend also occurred for the BZ surface soils in the present study.…”