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Survey of Global Expertise on Soil Biodiversity

This survey has been conducted for FAO by consultants Dan Bennack (Mexico) and George Brown (Brazil) to assess professional backgrounds and field work, to identify case studies and also ascertain interest in collaboration and partnerships for work on soil biodiversity and agriculture. The main findings of the survey, based on respondents, underline the following state of knowledge and what is missing:

State of knowledge and ongoing work:

1. Soil biodiversity experts are largely multidisciplinary and primarily experts in ecology, soil science, and zoology, and secondarily experts in microbiology, entomology, agronomy, and botany. A broad ecology approach is reflected by those with intersecting expertise in ecology, soil science, and zoology. These ecologists tend to have either a bias towards a systems science approach to ecology or a population/community ecology approach.

2. Soil biodiversity experts are working in a variety of field sites, in both agricultural lands and natural, undisturbed areas and under a range of climatic (temperature and precipitation) conditions and land use/ vegetation conditions. The majority of field sites are located in temperate-humid, temperate-sub-humid, and tropical-humid environments, with subtropical climate zones and arid regions around the world being strongly under-represented. Forests (other than rainforests) and grasslands are the most common native vegetation types reported among SBD field sites. These are followed by rainforest and savannah sites while deserts and steppes are seldom reported.

3. Soil biodiversity experts are studing a wide variety of soil organisms and soil processes. Experts in earthworms, soil and litter arthropods, roots, nematodes, and mycorrhizal fungi are more common. The work is mainly focusing on organic matter inputs, decomposition rates, enhanced bioavailability, nutrient pools and transformations, soil physical properties.

4. Respondents cited approximately 140 case studies and literature references, of these some 20 citations are of particular interest to FAOs work. These are equally divided into those referring to soil-dwelling invertebrates (such as earthworms, mites, spiders, and termites) and to those dealing with microorganisms (including nematodes, bacteria, fungi, and especially rhizobial bacteria and mycorrhizal fungi). A number of good reviews of the roles of soil biodiversity in ecosystem functions are available.

5. More than 100 ongoing projects are reported worldwide on various SBD themes, including: (1) the significance of ecosystem complexity in maintaining soil organism diversity, (2) the effects of agricultural managements on soil organisms, and (3) the role of soil biodiversity and specific soil taxa on various ecosystem functions.

6. The importance of soil biodiversity to plant diversity and agricultural productivity has been the subject of anecdotal and empirical investigation for some time, but only recently has research in this area really blossomed. Recent and pioneering investigations have been established through detailed, and oftentimes sophisticated, experimental designs (e.g. controlled manipulations of the soil biota, investigation of the impacts of biodiversity on ecosystem function, functional roles played by soil organisms in key ecological processes, etc.). Given the complex nature of relationships between soil biodiversity, plant diversity, and agricultural productivity, it is likely that this field will be active for many years to come, and that the number of projects, results and publications will continue to increase.

What is missing and what still needs to be done:

1. There is a notably lack of respondents with expertise in natural resource management, rural/community development, and plant pathology. This suggest a need for SBD experts to receive some formal training in natural resource management, rural/community development, and other disciplines having a social science focus. This would facilitate their interactions with farmer groups managing local land, water and biological resources.

2. South-south co-operation and work could be encouraged in subtropical climates and arid regions, including desert and steppes, in order to strengthen the knowledge base and facilitate delivery of soil biodiversity expertise to these important, but often marginalized, agricultural production zones. This could for example address agricultural practices related to open range and pastoral systems in regions unsuitable for cropping, and dryland and irrigated cropping occur along major watercourses, deltas, and floodplains in these regions (e.g., along the Nile River).

3. Experts working on soil and litter fungi, rhizobial bacteria (i.e. nitrogen-fixers), and fungal root pathogens are relatively under-represented. This is an area of concern as many of these organisms participate in crucial and unique symbiotic relationships with plants that either facilitate nutrient uptake (mycorrhizal fungi) or convert atmospheric nitrogen to readily utilizable forms (rhizobial bacteria). Soil processes such as nitrogen fixation, biogenic structures, soil physical processes, and bioaccumulation/degradation were little reported by survey respondents. Similarly not much work was reported on biological inputs (i.e. inoculants), tillage and inorganic fertilizers and the least in the areas of pesticides and pH adjustments. (More information needs to be collected from specialists working in the agricultural sector on such issues).

4. The state of knowledge of the relationship between soil biodiversity, plant diversity, and agro-ecosystem productivity is not clear from the review of case studies and citations, which are mostly narrow in scope and highly taxon-specific. Few case studies and reports considered soil biodiversity from multi-taxa, multi-functional, or multi-disciplinary perspective. Surprisingly there are no unifying theme considering that soil "biodiversity" might affect agricultural productivity in ways that differ from the effects of individual species. Some studies, for example, refer to the effects of individual soil taxa on agricultural productivity, but do not consider the effects of overall taxonomic diversity (for example including inter-specific or higher level comparisons). Other studies refer to the effects of landscape or crop (i.e., patch) heterogeneity on the presence, abundance, or biomass of soil organisms, yet these studies often fail to consider simple measures of organismal diversity (such as species and/or higher taxon richness, or other diversity measures based upon relative abundance, population size, biomass, recapture, etc.). Some investigations consider the influence of agricultural practices on certain types of soil organisms; yet ignore the impact of these practices on taxonomic and/or functional diversity per se. The absence of a unifying biodiversity theme among the case studies and literature references is of concern as it suggests that most experts polled in this survey were unclear about the possible importance of large-scale soil phenomena that might be attributed to an assemblage of diverse, interacting soil organisms.

5. In the ongoing projects on various SBD themes there may be a need to encourage strategic alliances among individual investigators and basic and applied research institutions. This would enable more effective incorporation of theoretical advances and practical applications into field programmes.

6. It is recommended that FAO pay special attention to research and development in the area of soil biological diversity. In this way, the theoretical advances as well as practical applications of basic research might be rapidly incorporated into field activities in the food and agricultural sector. This could be achieved by strengthening partnerships between agricultural practitioners and academic and other institutions undertaking SBD research.


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