SELECTED PUBLICATIONS FROM 1997 WORKSHOP

    Freckman, D W; Blackburn, T H; Brussaard, L; Hutchings, P; Palmer, M A; Snelgrove, P V R.  Linking biodiversity and ecosystem functioning of soils and sediments.  Ambio, v.26, n.8, (1997): 556-562.

Abstract:

Soils, freshwater sediments and marine sediments offer a new frontier of vast, poorly known ecosystems that are critical to life on earth. They are connected by similarities in biota, ecosystem processes, biogeochemistry, and, the types of processes carried out by the diversity of biota. We know a lot about the ecosystem processes in these domains through studies of functional groups of organisms, but we know much less about keystone species, or biodiversity across habitats and thus we cannot, with certainty, answer questions such as, "will a change in diversity in an agricultural soil affect the flow of energy, water and chemicals across the interconnected domains?". Linkages of knowledge across the three domains would increase our understanding of how human-driven changes affect subsurface biodiversity and functioning, and, in turn, how these impacts influence aboveground ecosystem functioning.  Approaches utilizing this knowledge will identify the long term strategies needed to attain sustainable soils, freshwaters and marine systems. Syntheses of available data for comparisons of biodiversity and processes across soils and sediments are priorities.

Abstract:

We review the current knowledge on biodiversity in soils, its role in ecosystem processes, its importance for human purposes, and its resilience against stress and disturbance. The number of existing species is vastly higher than the number described, even in the macroscopically visible taxa, and biogeographical syntheses are largely lacking. A major effort in taxonomy and the training of a new generation of systematists is imperative. This effort has to be focussed on the groups of soil organisms that, to the best of our knowledge, play key roles in ecosystem functioning. To identify such groups, spheres of influence (SOI) of soil biota-such as the root biota, the shredders of organic matter and the soil bioturbators-are recognized that presumably control ecosystem processes, for example, through interactions with plants. Within those SOI, functional groups of soil organisms are recognized. Research questions of the highest urgency are the assignment of species to functional groups and determining the redundancy of species within functional groups. These priorities follow from the need to address the extent of any loss of functioning in soils, associated with intensive agriculture, forest disturbance, pollution of the environment, and global environmental change. The soil biota considered at present to be most at risk are species-poor functional groups among macrofaunal shredders of organic matter, bioturbators of soil, specialized bacteria like nitrifiers and nitrogen fixers, and fungiforming mycorrhizas. An experimental approach in addressing these research priorities is needed, using long-term and large-scale field experiments and modern methods of geostatistics and geographic information systems.

Abstract:

All freshwater eventually passes through or over sedimentary habitats on the way to oceanic or atmospheric domains. These zones of freshwater sediments contain an enormous variety of species that produce and process organic carbon. Some species perform specific functions such as fixing or recycling nitrogen. Others break down contaminants or mix sediments so as to alter the rates of ecosystem processes. Approximately 175 000 species have already been described and yet still, new species continue to be discovered. Their diversity and distributions range greatly along gradients of depth, dissolved oxygen, latitude, and altitude in wetlands, lakes, rivers, and groundwaters. Deep, isolated habitats contain unique, endemic species especially among those organisms with limited dispersal ability. Competent scientists must be trained in many parts of the globe to accelerate studies of this species-rich biota and essential ecosystem relationships.

Abstract:

Sedimentary habitats cover most of the ocean bottom and therefore constitute the largest single ecosystem on earth in spatial coverage.  Although only a small fraction of the micro-, meio- and macroscopic benthic organisms that reside in and on sediments have been described and few estimates of total species numbers and biogeographic pattern have been attempted, there is sufficient information on a few species to suggest that sedimentary organisms significantly impact major ecological processes. Benthic organisms contribute to regulation of carbon, nitrogen, and sulfur cycling, water column processes, pollutant distribution and fate, secondary production, and transport and stability of sediments. Linkages between groups of organisms and the level of functional redundancy is poorly known, however, there is probably substantial redundancy within groups. There is little evidence that biodiversity per se is necessary for benthic systems to contribute to ecosystem services, but because linkages are so poorly known and predictive knowledge confined to a few species, it is not presently possible to predict exactly how species loss will impact these services and ecosystem health. Thus, a precautionary approach of "assume the worst" is advised, and every effort should be made to curtail the species and genetic diversity loss resulting from fishing, pollution, habitat destruction, introduction of non-native (exotic) species, and global warming. Concurrently, scientists must take advantage of exciting, rapidly evolving technology and a rejuvenated interest in biodiversity to provide more concrete and thorough information on benthos and ecosystem processes.

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