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Please note: This research Programme is no longer active

 

 


 


 

The Soil Biodiversity Programme aims to achieve simultaneously:

  •  an understanding of biological diversity of the soil biota (embracing all abundant taxa, not just those normally considered tractable), 

  • and the functional roles played by soil organisms in key ecological processes. 

5.85 million has been allocated by the Natural Environment Research Council (NERC) for research and necessary support services. The Programme is closely integrated, to give insights of wider generality than the chosen ecosystem, an upland grassland at Sourhope, near Kelso, Scotland.  Research has been funded in two main phases, the first starting in 1998.  The second phase will run from 2001 - 2004.  Details of current  research projects and outputs can be found in the sections below.  Contact the Programme Office for more information or request access to data.

 

 


OBJECTIVES

The objectives of the Soil Biodiversity Programme are:

  1. To quantify the taxonomic and metabolic diversity of key groups in the soil biota in a single ecosystem, sufficient to provide a sure basis for an experimental programme to determine the role of diversity in ecosystem processes.

  2. To extend taxonomic understanding of the soil biota, especially by using isolation and molecular techniques to examine hitherto poorly characterised groups.

  3. To characterise the roles played by all major groups within the soil biota (including root–microbe associations) in ecologically important processes in the carbon and nitrogen cycles in soil, including the development of carbon sinks, so as to determine the pathways and rates of movement of carbon through components of the soil foodweb.

  4. To determine (both experimentally and by comparison of contrasting sites) the extent to which depauperation of the soil biota may reduce their ability to perform essential ecosystem services, including the ability to cope with anthropogenic inputs.

  5. To conduct parallel manipulations of major taxonomic groups of soil biota under controlled conditions.

  6. To determine the extent to which indicators of soil biodiversity are measures of the soil ecosystem resilience of relevance to land use management.

It is intended that research projects will use common experimental and identification protocols, allowing a robust test of the generality of the findings.

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BACKGROUND

BIODIVERSITY IN SOIL
A central question in ecology is whether there is a necessary link between biological diversity and ecosystem function. Biogeochemical cycles are among the most fundamental of the functions performed in ecosystems, and many critical processes in these cycles (e.g. decomposition, nitrogen transformations, trace gas generation) occur in soil and are mediated by soil organisms. The role of these organisms in biophysical processes (e.g. hydrological cycling, energy balances) is unclear but almost certainly profound. Soil communities are currently exposed to a wide range of impacts, including erosion, agricultural intensification, and the deposition of acidic and nitrogenous pollutants, with poorly documented effects on diversity of the soil biota, and virtually unknown effects on ecosystem processes.

ROLE OF SOIL ORGANISMS
Soil organisms also control the magnitude and chemical nature of the globally significant C and N fluxes from soils. The role of some bacteria in these transformations is well established, but rates and pathways of soil biological processes are typically studied as functions of environmental rather than biological variables. The roles played by most groups of soil organisms is very poorly known, although a general theoretical and conceptual framework is emerging. Experimental demonstrations of the importance of faunal-microbial interactions are rarely performed in a context where their significance to ecosystem-level processes can be inferred.

NEW TECHNIQUES
Basic knowledge of the diversity of the soil biota is rudimentary. Molecular techniques confirm that the undescribed diversity is large, and that this genetic diversity can be linked to process studies if it can be characterised using molecular probes and taxa assigned to functional groups. Molecular techniques now offer an unique way forward when combined with other new or advancing technologies (e.g. NMR, confocal microscopy, GC-MS) to frame answerable questions about the diversity/function relationships in soil.

 

RATIONALE
The Programme will combine detailed taxonomic description with an experimental approach designed to utilise that description to test hypotheses about the functional role of biodiversity. It will be based on an intensive study of a single site. Diluting the effort over a range of sites would preclude proper investigation of functional links between taxonomic diversity and function, and intensive studies at a range of sites would be prohibitively expensive.

FIELD LOCATION
The research will focus on a grassland system at the Sourhope Research Station in the Cheviot Hills, which is part of the UK Environmental Change Network and the most thoroughly studied site in the SOAEFD MicroNet programme. Sourhope has extensive areas of upland grassland (Agrostis-Festuca; National Vegetation Classification U4), for which data on microbial diversity are already becoming available. 

ECOTRON
The Programme will also have access to the Ecotron facility, at the Centre for Population Biology (CPB) Imperial College, in which a simplified grassland ecosytem will be created with communities of varying diversity to defined taxonomic specifications. A key part of the field and Ecotron-based parts of the Programme will involve the introduction of a large pulse of 13C to the grassland ecosystem and monitoring progress of this signal through the soil ecosystem which will be manipulated so as to alter its structure. The 13C pulse will be added to the Ecotron system early in the life of the Programme and results from these mesocosm studies will be used to generate predictions about expected responses in the field. A pulse will be added in the field following a period of characterisation and protocol development.

EXPERIMENTS
A series of manipulation experiments will be applied to large plots at Sourhope and used to test a number of hypotheses, for example:

  1. Reducing the diversity of the soil community will increase the residence time of carbon in soil pools, but that surviving taxa will react and compensate for such reductions.

  2. Specific taxa (benchmark organisms or groups) play key roles in this process.

  3. Rates of carbon cycling are less sensitive to the quality of the carbon inputs when the diversity of the soil community is high.

  4. Taxonomic and functional diversity of the soil community is reduced by physical and chemical perturbations.

  5. Resilience of the ecosystem will be greatest when diversity is high.

MANIPULATIONS
Proposed field manipulations include:

  1. Changes in carbon and nitrogen inputs by removal of grass litter (following mowing) from all plots and its addition to other plots, or by selective grazing.

  2. Application of a biocide, which would remove or reduce selected taxa. Although the limitations of this technique are recognised, it has been used successfully to determine changes in soil foodwebs and ecosystem properties. An Ecotron experiment would create ecosystems that mirror the effects of these field treatments, by omitting specific taxa from the artificial communities in a replicated design. If possible, soil fungi could also be manipulated in this way.

  3. Application of a pollutant (e.g. a heavy metal) which would affect most taxa indiscriminately and also provide a further signal whose progress through the foodweb can be monitored; identical pollutants can be added to mesocosm communities.

  4. Some plots will receive a short perturbation and the recovery studied to allow some assessment of resilience. Additional manipulations are possible within this design, including those aimed at measuring the effect of global change factors (temperature, uv penetration) or land-use (change from grassland to arable), and ancillary studies such as an intensive study of decomposition.

  5. There will be a need for laboratory microcosm work to characterise the metabolic and functional capabilities and environmental tolerance ranges of key species and groups identified from the field studies.

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