Scoping biological indicators of soil quality Phase II. Defra Final Contract Report SP0534

This report presents results from a field assessment of a limited suite of potential biological indicators of soil quality to investigate their suitability for national-scale soil monitoring

Effects of acute gamma irradiation on chemical, physical and biological properties of soils

The use of gamma (-) irradiation as a method for soil sterilisation for laboratory experiments has been recommended over other sterilisation techniques.We reviewed literature dating back over 50 years to investigate the chemical and biological effects on -irradiated soils and to determine its practicality for sterilising soils which will subsequently be used for experimental purposes. Typically, -irradiation at 10 kGy will eliminate actinomycetes, fungi and invertebrates in most soils. The majority of soil bacteria are eliminated by 20 kGy, however, a dose higher than 70 kGy may be required to kill certain radio-resistant bacteria. We recommend prior to experimentation that the radiosensitivity of soils are determined so as to ensure the desired chemical and biological effects are achieved. -Irradiation may not be an appropriate method for all experiments as it can influence soil chemical properties, in particular soil nitrate and ammonium levels. Where chemical stability is required we recommend sterilising soils air-dry rather than moist

SQID: Prioritising biological indicators of soil quality for deployment in a national-scale soil monitoring scheme. Summary report

This project prioritised thirteen biological indicators of soil quality which showed high current potential for deployment in a national-scale soil monitoring scheme. These indicators met a range of scientific and technical criteria that related soil functions and feasibility within large-scale surveys. The priority indicators with associated methodologies are: - Eight soil microbial groups [ammonia oxidisers, denitrifiers, fungi, bacteria, Archaea, methanogens, methanotrophs and actinomycetes] identified from TRFLP fingerprinting - Soil microbial community structure and biomass characterised from PLFA profiles - Multiple substrate induced respiration (MSIR) derived by GC or MicrorespTM - Multi-enzyme profiling via microplate fluorometric assay - Nematode community structure from Baermann extractions - Microarthropod community structure from Tullgren dry extractions The selection process was robust, repeatable and auditable. A structured framework denoted a 'logical sieve' was developed to support the incorporation and analysis of a large number of assessments against a wide range of technical and scientific criteria relevant to national scale soil monitoring. This enabled a consistent synthesis of available information and the semi-objective assessment of 183 potential biological indicators identified from the literature. Stakeholder priorities for technical criteria were identified through consultation, with the UK-SIC and the expert reviewers, and incorporated into the final prioritisation phase of the logical sieve. The power of this approach is that it provides a clear audit trail on the decision-making process and would allow the inclusion of further indicators into the framework. The process was initially reviewed by experts familiar with biological indicators and soil monitoring and then assessed at a two-day expert workshop. Comments and discussions on the relative importance and robustness of potential indicators and future research priorities proved invaluable to the final selection. As a consequence, the logical sieve was modified to prioritise biological indicators for all three soil functions rather than simply biological indicators with the highest universal scores. The final priority indicators were selected by reviewing the outputs from the logical sieve. Each priority indicator, with associated method, was assessed for relevance to ecological services, obvious surrogacy, the range of indicator indices produced and practicalities of use. Each priority indicator was reviewed and outstanding issues relating to deployment identified. Statistical analyses of existing field survey/experimental data for PLFAs, soil invertebrates and community-level physiological profiling of the soil microbial community (BIOLOGTM) highlighted generic technical, policy-related and scientific issues which were considered in the recommendations for a field evaluation of the priority indicators

The function of soil biodiversity as indicators of soil quality: Insights from the UK Defra SQID project

This presentation outlines the final results from the UK Defra SQID project which identified and piloted a suite of biological indicators of soil quality for deployment in national-scale soil monitoring programmes to meet a range of UK policy objectives. The indicators were selected to provide information on the soil biological processes which underpin soil function and therefore support ecosystem services. A semiquantitative framework was used to systematically capture the wealth of information in the literature and from expert knowledge on potential indicators of soil quality with a total of 183 indicators assessed. Six soil biological methods have now been piloted in the UK using two complementary field approaches. These six reflect the genotypic, phenotypic and functional characteristics of soil biodiversity. Here we review the results from the two field approaches, the first to assess the temporal sensitivity of biological indicators to key environmental pressures across a 12 month window and the second to asses the ability of biological indicators to discriminate between different habitats. We discuss the relative performance of the indicators and how these were prioritised for national-scale soil monitoring and finally, how this process has revealed new insights into the distribution and characteristics of soil biological properties within UK soils and habitats

Natural capital and ecosystem services, developing an appropriate soils framework as a basis for valuation

Natural capital and ecosystem service concepts are embodied in the ecosystems approach to sustainable development, which is a framework being consistently adopted by decision making bodies ranging from national governments to the United Nations. In the Millennium Ecosystem Assessment soils are given the vital role of a supporting service, but many of the other soil goods and services remain obscured. In this review we address this using and earth-system approach, highlighting the final goods and services soils produce, in a stock-fund, fund-service model of the pedosphere. We also argue that focusing on final goods and services will be counterproductive in the long run and emphasize that final goods and services are derived from an ecosystem supply chain that relies on ecological infrastructure. We propose that an appropriate ecosystems framework for soils should incorporate soil stocks (natural capital) showing their contribution to stock-flows and emergent fund-services as part of the supply chain. By so doing, an operational ecosystems concept for soils can draw on much more supporting data on soil stocks as demonstrated in a case study with soils data from England andWales showing stocks, gaps in monitoring and drivers of change. Although the focus of this review is on soils, we believe the earth-system approach and principles of the ecosystem supply chain are widely applicable to the ecosystems approach and bring clarity in terms of where goods and services are derived from

Rising atmospheric CO2 reduces sequestration of root-derived soil carbon

Forests have a key role as carbon sinks, which could potentially mitigate the continuing increase in atmospheric carbon dioxide concentration and associated climate change. We show that carbon dioxide enrichment, although causing short-term growth stimulation in a range of European tree species, also leads to an increase in soil microbial respiration and a marked decline in sequestration of root-derived carbon in the soil. These findings indicate that, should similar processes operate in forest ecosystems, the size of the annual terrestrial carbon sink may be substantially reduced, resulting in a positive feedback on the rate of increase in atmospheric carbon dioxide concentration