المنتدى العالمي المعني بالأمن الغذائي والتغذية

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    • 1. Biodiversity is an important contributor to food security and improved nutrition.

      There are numerous examples of soil organisms playing crucial roles in regulating key soil functions that sustain crop growth. Some examples from our work include:

      (a) Working in grasslands we have shown that management practices that enhance the abundance of fungi relative to bacteria in soil are associated with more efficient nutrient cycling and reduced nutrient loss from soil (Bardgett et al. 2003), especially following perturbations (e.g. dry/wet cycles) (Gordon et al. 2008; De Vries et al. 2012a).

      (b) As part of a large pan-European study, we shown that intensive agriculture universally reduces soil food web diversity and the abundance of most functional groups, and that soil food web properties strongly and consistently predicted processes of carbon and nitrogen cycling across a wide range of contrasting geographic locations and land uses. Not only did this study provide the first quantification of relationships between soil food web complexity and ecosystem processes at larger spatial scales, but also it demonstrated the need to include soil food web parameters in biogeochemical models (De Vries et al. 2013).

      (c) In a related study, we showed that reductions in soil food web complexity and diversity caused by intensive land use, especially a reduction in the ‘slow’ fungal relative to the ‘fast’ bacterial energy channel, strongly impairs their ability to resist and recover from extreme climatic events, in this case drought. This then causes increased loss of carbon and nitrogen from soil to the atmosphere and in drainage waters (De Vries et al. 2012b). These findings have implications for sustainable land management, because they provide evidence that extensive agricultural management can promote more resistant, and adaptable, fungal-based soil food webs, thereby contributing to ecosystem services such as soil nitrogen retention, which is of central importance to sustainable food production and pollution mitigation.

      2. Where a (sustainable) production system played a key role for the conservation of the biodiversity surrounding it and where a(n) (unsustainable) production system played a key role for the degradation of the biodiversity surrounding it?

      In a paper by De Vries and Bardgett (2012) we proposed various ways by which the he promotion of plant–microbial linkages in agricultural systems has the potential to enhance N retention and reduce N loss. Although trade‐offs with agricultural yield are inevitable, we suggest that promoting plant–microbial linkages will reap benefits in terms of plant crop resistance to climate change as well as to pests and diseases. As an example of declines in biodiversity associated with intensive management,

      Tsiafouli et al. (2015) examined biodiversity in soil food webs from grasslands, extensive, and intensive rotations in four agricultural regions across Europe, and found that land‐use intensification reduced the complexity in the soil food webs, as well as the community‐weighted mean body mass of soil fauna. In all regions across Europe, species richness of earthworms, Collembolans, and oribatid mites was negatively affected by increased land‐use intensity. The taxonomic distinctness, which is a measure of taxonomic relatedness of species in a community that is independent of species richness, was also reduced by land‐use intensification. We concluded that intensive agriculture reduces soil biodiversity, making soil food webs less diverse and composed of smaller bodied organisms.

      References

      Bardgett, R.D., Streeter, T. and Bol, R. (2003) Soil microbes compete effectively with plants for organic nitrogen inputs to temperate grasslands. Ecology, 84, 1277-1287.

      De Vries, F.T., E. Thébault, M. Liiri, K. Birkhofer, M.A. Tsiafouli, L. Bjørnlund, H. Bracht Jørgensen, M.V. Brady, S. Christensen, P.C. de Ruiter, T. d’Hertefeldt, J. Frouzk, K. Hedlund, L. Hemerik, W.H.G. Hol, S. Hotes, S.R. Mortimer, H. Setälä, S.P. Sgardelis, K. Uteseny, W.H. van der Putten, V. Wolters, and Bardgett, R.D. (2013). Soil food web properties explain ecosystem services across European land use systems. Proceedings of the National Academy of Sciences, 110, 14296-14301.

      De Vries, F., Bloem, J., Quirk, H., Stevens, C., Bol, R. and Bardgett, R.D. (2012a) Extensive management promotes plant and microbial nitrogen retention in temperate grassland. PLoS ONE, 7(12).

      De Vries, F.T. and Bardgett, R.D. (2012) Plant-microbial linkages and ecosystem N retention: lessons for sustainable agriculture. Frontiers in Ecology and the Environment, 10, 425-432.

      De Vries, F.T., Liiri. M., Bjørnlund, L., Bowker, M.A., Christensen, S., Setälä, H.M. and Bardgett, R.D. (2012) Land use alters the resistance and resilience of soil food webs to drought. Nature Climate Change, 2, 276-280.

      Gordon, H., Haygarth, P.M. and Bardgett, R.D. (2008) Drying and rewetting effects on soil microbial community composition and nutrient leaching. Soil Biology and Biochemistry, 40, 302-311.

      Tsiafouli, M., E. Thébault, S. Sgardelis, P. de Ruiter, W.H. van der Putten, K. Birkhofer, L. Hemerik, F.T. de Vries, R. D. Bardgett, M. Brady, L. Bjørnlund, H. Jørgensen, S. Christensen, T. D'Hertefeldt, S. Hotes, W.H.G. Hol, J. Frouz, M. Liiri, S. Mortimer, H. Setala, J. Tzanopoulos, K. Uteseny, Karoline, V. Pižl, J. Stary, V. Wolters, and K. Hedlund. (2015) Intensive agriculture reduces soil biodiversity across Europe. Global Change Biology, 21, 973-985.