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GROUP 2 Biodiversity

Working group members and contributors

Biodiversity

Outline of the issues

3.1 Biodiversity is described as "the variety of life on earth and all interactions taking place between species and community assemblages. …". Biodiversity is the natural capital, which supports all our lives. It is vital for our survival and is a key measure of the health of our planet.

3.2 Soil biodiversity refers to all soil dwelling species as well as those species which spend part of their life cycle below ground. We know little about the extent and nature of soil biodiversity but we are now aware it is very large indeed. It is often described as a "true scientific frontier". Soil biota can be differentiated by taxons, genotypes and functions. Soil biodiversity is a component of soil diversity which in turn is part of our geodiversity. Soil biota can also be grouped in functional groups that indicate their wide-ranging role and importance. Soil biodiversity includes primary producers, decomposers, nitrogen fixers, ecosystem engineers (macro and micro), plant mutualists and plant symbionts. The greatest value of our soil biodiversity is the ecological services the organisms perform which underpin all of soil's ecological functions.

3.3 There are many potential causes of the loss of biodiversity. The Millennium Ecosystem Assessment (2003) listed the key threats to biodiversity worldwide as loss and damage of habitats, climate change, invasive non-native species and overexploitation of species. These apply equally to soil biodiversity. Any physical loss of soil can inevitably lead to loss of biodiversity and any change in land use or vegetation is likely to alter soil biodiversity. There are several potential causes of the loss of biodiversity such as loss of organic matter; climate change, erosion/loss of structure, contamination, habitat loss, invasive species, changing land use and soil management.

Impacts on soils

2.1 Biodiversity underpins all of soil's ecological functions and either drives or contributes to many of the ecosystem processes we rely on. A diverse and active pool of organisms provides multiple metabolic functions that recycle beneficial nutrients via decomposition, fix atmospheric nitrogen, degrade and transform pollutants to protect the food chain and water supply, produce trace gases, develop and maintain soil structure via a variety of mixing, particle binding and surface coating processes that help to resist erosion and promote effective drainage. Loss of biodiversity can therefore affect all of the functions and ecosystem services provided by soil.

2.2 Hence plant biomass production can be reduced by loss of soil biodiversity indirectly if soil physical structure, nutrient cycling, plant-microbe symbiotic nutrient uptake are reduced or if there were losses of plant growth promoting organisms or organisms that protect plants from pathogens. Agricultural and environmental policy and economics (e.g. market forces) will continue to be major drivers of both land use change and land management practices and thus impact on soil biodiversity. Public opinion will influence both policy and market drivers, for example, through attitudes to alternative energy or waste management systems or demands for products from outdoor rearing of pigs and poultry. Changes in land use and management practices will affect soil biodiversity and functionality of soil, but the direction of change and intensity need still to be clarified (e.g. Stockdale et al., 2006). Important changes include new crops or cropping patterns e.g. biofuels, different agrochemical regimes which will impact on above and below ground biodiversity. Agri-environment schemes are also expected to have positive impacts on soil biodiversity but this will need to be confirmed. The spread of invasive and alien species may also be affected by changes in land management practices.

2.3 Soil biodiversity has a major effect on soil's environmental function. The metabolism or transformation of pollutants coupled with effects on soil structure have consequences for the transport and movement of pollutants to waters and the atmosphere so affecting the buffering, filtering and transformation functions of soil. Trace gas production (methane, nitrous oxide, carbon dioxide) is also due to biological activity and provides an important feedback and regulation of our global climate.

2.4 Carbon stored in soil and the exchange of greenhouse gases may also be adversely affected by loss of biodiversity or altered biological functions. Climate change will also alter land use and land management as well as directly influencing soil biodiversity. Losses in stored carbon would fundamentally alter the physical and chemical nature of soil and have major effects on soil biodiversity.

2.5 Soil biodiversity has inherent value as a component of our ecosystems and any loss detracts from soil's habitat function. Clearly loss of specific protected soil fauna can be not only detrimental to soil quality but also the maintenance of favourable conservation status of protected habitats. Soil biodiversity is also part of a food web which links directly to higher food chains e.g. many soil invertebrates are a vital food resource for birds. There are few data or models available on food webs based on soils typical of Scotland (except Sourhope-grassland see Fitter et al., 2005). The development of a food-web model for different soil systems may provide a useful tool to explain in simple term the value and role of soil biodiversity to land manager and impact of change on whole soil ecosystems (DeRuiter et al., 1994). Rare and valued habitats are often linked to specific soil and soil biodiversity properties (Towers et al., 2006). Sustainable management of soil and soil biodiversity is essential to delivery of conservation objectives and should also be an essential component of any restoration project. The large and unexplored diversity of organisms in soil also represents a potentially valuable genetic reservoir of new organisms, enzymes, pharmaceutical and other bioactive compounds that might be useful in a wide range of biotechnological industries.

2.6 There is limited information about the effects of biodiversity on the heritage function. However, if soil processes which are control by soil biodiversity change, previously well-preserved material may degrade more rapidly. As well as microbial activity the effects of soil macrofauna (earthworms, rabbits, badgers, moles etc.) and roots are potentially of concern for the preservation of archaeological artefacts. There is no known significant impact of loss and change of biodiversity on the provision of raw material from soil or as a foundation for building and road.

The impacts in Scotland

2.7 A major impediment to evaluating any loss in biodiversity is the lack of systematic data that describes its current status and distribution. There are already soil organisms on Biodiversity Action Plans ( BAP) group species lists which include fungi and ephemeral soil dwellers and these are protected by habitat BAPs. Towers et al. (2006) reviewed the evidence and consequence of loss of biodiversity in Scotland and identified four main areas were there was evidence of :

• historic loss of pinewoods in relation to rare woodland fungi and ants
• habitat loss and nutrient enrichment of grasslands in relation to rare grassland fungi
• changes in earthworm populations due to invasive New Zealand flatworm
• heavy metal contaminated sludge reducing N fixing bacteria

2.8 There are also significant threats to habitats from atmospheric deposition, nutrient enrichment which have follow-on effects on soil biodiversity. This is most apparent in relation to threatened high value habitats such as the montane and Machair habitats that exist on soil resources that cover a small extent.

2.9 Most of these threats vary in the extent of soil that might be affected and more work is needed to fully evaluate the full consequences.

Data and evidence gaps

2.10 While there is evidence for losses of biodiversity and function this is from specific experimental sites and small scale studies and there has been no extrapolation to the whole of Scotland. This argues further for more systematic data with which to gather evidence of change.

2.11 For example there is little direct evidence of specific impacts of Climate change in Scotland on Biodiversity and there are major gaps in understanding how biodiversity may respond. If predicted losses of soil Carbon found in England and Wales (Bellamy et al., 2005) were to occur in Scotland's soils there would be a very significant impact on soil biodiversity in our dominant organic Carbon rich soils as the activity and diversity of organisms is directly linked to the amount of organic Carbon available as an energy source and it provides a distinct physical habitat. The direct impact of climate change will vary across Scotland. Trends could be assessed but exact prediction of intensity of change is difficult due to uncertainty in existing climate change scenarios as well as a lack of good quality data and systematic baseline data on soil biodiversity. Climatic changes will directly affect primarily temperature and wetness. There is as yet an unknown degree of resilience and resistance of soil biodiversity to change and expected redundancy of functionality in the soil microbial community. For example higher water content will reduce oxygen level in soils and could be detrimental to some soil fauna such as invertebrates.

2.12 The link between diversity and function is a topic of much international research in national, continental and global research programmes. There is a need to understand more fully the linkage between soil biodiversity and function relevant to the Scottish context and a set of priorities established that address knowledge gaps as a result. Several research funders have commissioned research in the past relating soil biodiversity to anthropogenic activities and how the role of biodiversity in relation to geochemical cycling (e.g. NERC Soil Biodiversity Programme, SEERAD MicroNet) but given the extant of diversity in soil we are still at an early stage of understanding. Consequently we still need to understand further how soil biodiversity contributes to the regulation of greenhouse gases and loss of soil Carbon as well as adapt to future climatic conditions. Data on soil biodiversity is key to enhance our understanding of the processes and factors controlling the relationships between soils, habitats and ecosystems, especially for those habitats considered most at risk.

2.13 Research in the Scottish Government RERAD research programme on 'Protecting the Nation's Soils' has a significant emphasis on soil biodiversity namely to develop and test new biological indicators including methods to quantify diversity and the first systematic grid survey of soil biodiversity in Scottish soils via a re-sampling of the National Soils Inventory of Scotland ( NSIS).

2.14 One key issue for the strategy will be to address the definition and quantification of the values attached to soil, its biodiversity and the functions it supports.

2.15 There are few data or models available on food webs based on soils typical of Scotland (except Sourhope-grassland see Fitter et al., 2005). The development of a food-web model for different soil systems would provide a useful tool to explain in simple term the value and role of soil biodiversity to land manager and impact of change on whole soil ecosystems (DeRuiter et al., 1994) that take account of typical Scottish soil conditions.

2.16 Rare and valued habitats are often linked to specific soil and soil biodiversity properties (Towers et al., 2006). The link between soil biodiversity and rare habitats, such as Machair and peatland, is in part currently being investigated though the Scottish Government RERAD Work Programme 3 ¹ (This will deliver medium to long-term research outcomes on special soil / habitats. The relationship between soil and biodiversity features in designated sites ( SSSI, National Park) has also been reviewed (Towers et al., 2006, 2007), and should inform management of protected habitats and species. Sustainable management of soil and soil biodiversity is essential to delivery of conservation objectives and should also be an essential component of any restoration project.

2.17 A major issue with soil biodiversity is that we have a limited understanding of its true extent and in Scotland no knowledge of how unique it may be in either our common forest and agro-ecosystems or our rare and valued habitats. This and a lack of systematic data that describes its current status is a major impediment to evaluating current and future losses in biodiversity.

Relevant policies

2.18 In recent years, there have been numerous policy reviews of soil protection in Scotland. There are also a number of legislation / policy / incentives measures / voluntary codes affording some level of protection to soil (direct and indirect) (see graph below, Items in bold italics have some reference to protect soil biodiversity).

2.19 However it is not implicit in any of them that they are protecting soil biodiversity. For example the benefits of recycling wastes to soil are presently poorly defined as being of "ecological benefit" and may not always protect or enhance biodiversity. The added organic matter may increase biomass and diversity on some soils but potentially toxic contaminants may reduce or alter diversity and on some soils added organic matter may alter soil properties to the detriment of biodiversity. Hence there may be conflicts between some policies.

2.20 The UK government has signed up to the Convention on Biological Diversity ( CBD) and to the European Union target to halt the loss of biodiversity by 2010. Other international initiatives explicitly considering soil biodiversity have been established under the auspices of the UNEPCBD² which in part recognises the role soil biodiversity can play in more environmentally friendly agriculture. In Scotland the Nature Conservation (Scotland) Act 2004 makes it a duty on all public bodies to further the conservation of biodiversity. The Scottish Biodiversity Strategy (2005) sets out what we need to do to conserve and enhance biodiversity over the next 25 years. Soil biodiversity is also explicitly protected in the "ecosystem approach" adopted as a framework in this and subsequent conventions and was recognized as crucial to the global sustainability of our ecosystems and welfare of mankind in the Millennium Ecosystem Assessment (Millennium Ecosystem Assessment, 2003).

2.21 Loss of soil biodiversity is one of the threats recognised by the Soil Thematic Strategy ³ and the proposed Soil Framework Directive ( SFD). Although not dealing directly with soil biodiversity its implementation will drive forward the soil protection agenda and soil monitoring activities in UK. Outcome of SFD may change how biodiversity is perceived and acted in other EU and international framework and result in increased awareness of its importance.

References

Bradley et al. (2006) - Guidance on understanding and managing soils for habitat restoration project. English Nature Research report 712.

Bellamy, P.H, Loveland, P.J., Bradley, R. I., Lark, R.M and Kirk, G.J.D. (2005) Carbon losses from all soils across England and Wales 1978-2003. Nature. 437:245-248

Brooker, R.W., Carrs, D. et al. (2004). Incorporation of Climate Impacts into Biodiversity Action Plans relevant to Scotland. SEERAD Project Commission Number CEH/002/03, Centre for Ecology and Hydrology, Banchory No. 38. (The report is accompanied by a CDROM with Excel spreadsheets too large to print out.)
http://www.scotland.gov.uk/Topics/Environment/Wildlife-Habitats/14870/11172

Brussard L, de Ruiter PC & Brown GG. Soil biodiversity for agricultural sustainability. Agriculture Ecosystems and Environment Volume 121, Issue 3, July 2007, Pages 233-244

Countryside Survey (2000) Module 6: Soils and Pollution. R&D Technical Report E1-063/TR. 2002. H I J Black, J S Garnett, G Ainsworth, P A Coward, R Creamer, S Ellwood, J Horne, M Hornung, V H Kennedy, F Monson, L Raine, D Osborn, N R Parekh, J Parrington, J M Poskitt, E Potter, N Reeves, A P Rowland, P Self, S Turner, J Watkins, C Woods and J. Wright.

de Ruiter, P. C., Neutel, A. M., & Moore, J. C. 1994, "Modeling food webs and nutrient cycling in agroecosystems", Trends In Ecology & Evolution, vol. 9, pp. 378-383.Fitter, A. H., Gilligan, C. A., Hollingworth, K., Kleczkowski, A., Twyman, R. M., & Pitchford, J. W. 2005, "Biodiversity and ecosystem function in soil", Functional Ecology, vol. 19, no. 3, pp. 369-377.

Hossell, J.E., Briggs, B. and Hepburn, I.R. (2000). Climate Change and UK Nature Conservation: a review of the impact of climate change on UK species and habitat conservation policy. DETR, MAFF and ADAS.
http://www.defra.gov.uk/wildlife-countryside/climatechange/nature/index.htm

NSRI (2005) Impacts of climate change on soil functions, SP0538. Final project report to DEFRA. (available on erosion subgroup page)

RELU (2005) 'Soils - the foundation of the Rural Economy'
http://www.relu.ac.uk/research/projects/Watson.htm

Scottish Climate Change Impacts Partnership ( SCCIP) - Scottish Climate Change Impacts Partnership ( SCCIP)

Scottish Executive (2006) ECOSSE: Estimating Carbon in Organic Soils - Sequestration and Emissions: Final Report, web only publication,
http://www.scotland.gov.uk/Publications/2007/03/16170508/0.

Scottish Exectuive (2006) CHANGING OUR WAYS SCOTLAND'S CLIMATE CHANGE PROGRAMME http://www.scotland.gov.uk/Resource/Doc/100896/0024396.pdfSOC/ develop soil management strategy for soil biodiversity

SEPA (2006) - State of Scotland's Environment.
http://www.sepa.org.uk/publications/state_of/2006/main/d_climate_change.html

SNIFFER (2006)- An online handbook of climate trends across Scotland.
http://www.sniffer.org.uk/climatehandbook/index.html

SNIFFER (2004) The role of the planning system in protecting and enhancing soil. UKLQ01.

Stockdale et al. (2006) Do farm management practices alter below-ground biodiversity and ecosystem function? Implication for sustainable land use management. JNCC report series no364.

Sustainable Scotland Network (2007) - Scotland Climate change declaration.
http://www.sustainable-scotland.net/documents/climate-change-declaration.pdf

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