Soil formation, land use and biodiversity
Soil Transformation of European Catchments (SoilTrEC)-‐ Project Fact Sheet (www.soiltec.eu) Soil formation, land use and biodiversity Soil Biodiversity Soil ecosystems are habitat for extreme species rich communities. By far the most important groups of organisms are the microbes (bacteria, fungi, archaea) both in terms of biomass as in (genetic) diversity. In addition, soil communities harbor a range of microbial grazers (protozoa, nematodes, insects, mites), omnivores (enchytraeids, earthworms) and predators (nematodes, insect, mites). Together, these organisms create complex networks of trophic interactions, forming the soil food web (Figure 1). Herbivore C ollembola Diplura Herbivore nematodes Predaceous mites Herbofungivore mites Roots Herbofungivore Collembola Omnivore mites Nematovore mites Fungivore nematodes Stabile soil organic matter Fungi Predaceous nematodes Fungivore mites Omnivore nematodes Fungivore collembola Enchytraeids Labile Soil organic matter Bacterivore mites Bacterivore nematodes Bacteria Amoebae Flagellates Bacteria Fungi Fungivore Collembola Bacterivore nematodes Amoebae Fungivore mites Predatory mites Figure 1. Food web diagram of the soil community as observed in Austrian farms near Vienna. Boxes represent groups, arrows represent feeding rates. Colours denote the primary energy source, i.e. brown: soil organic matter, red: bacteria, blue: fungi. Black arrows denote more than one energy source. Grey boxes denote groups that were found over all sites but were not present in the Austrian soils. The functionality of Soil Biodiversity The tremendous reservoir of soil biological diversity is pivotal for delivering food, fibre and biofuels, clean air, drinking water and carbon storage. Because of increased intensive land use, it is expected that this soil diversity will be affected with negative impacts on these soil ecosystem services. Considerable efforts by landowners, policy-makers and scientists are directed towards optimizing land management for maximum functionality in terms of ecosystem services through sustaining the soil food-web governing this functionality. CO2 emission (kg/ha/yr) 6000 Fauna Microbes 5000 4000 3000 2000 1000 Damma 1 : 10 y r 2: 7 0 y r 3: 1 10 yr 4: 1 0.000 yr Fuchsenbigl 5: riverdune 6: w iesenfield 7: riverine forest 8: cropland 9: old forest Koiliaris 10: s ea level 11: s lope 12: 1 000 m Lysina 13: Lysina 14: P luniv Bor 15: N a Zelenem 0 1 2 3 4 5 6 7 8 9 1 0 11 12 1 3 14 15 D amma F uchsenbigl Koiliaris L ysina Figure 2. Soil can store and emit large amounts of carbon. Carbon storage and CO2 emissions are the direct result of the trophic activity of the soil organisms. In this way, soil biodiversity plays a major role in the global cycling of carbon. Land use that promotes carbon storage can make a significant contribution to climate change mitigation. Soil biodiversity along soil formation To understand the diversity and structure of the soil communities, and how these relate to ecosystem functioning and services, it is important to analyse pathways of development of soil food web structure. SoilTrEC has studied soil food web development along gradients of soil formation created by retracting glaciers in Switzerland and Iceland. Stage 1 2 3 Flagellates Amoebae Flagellates Amoebae Flagellates Labile SOM Bacteria Recalcitrant SOM Fungi Labile SOM Omnivorous nematodes Fungi feeding nematodes Bacterial Feeding nematodes Amoebae Labile SOM Flagellates Root Feeding nematodes Fungi Bacteria Recalcitrant SOM Predatory nematodes Omnivorous nematodes Bacteria 4 Recalcitrant SOM Amoebae Bacterial Feeding nematodes Fungi Bacteria Labile SOM Roots Fungi feeding nematodes Recalcitrant SOM Root Feeding nematodes Roots Figure 3. Retracting glaciers, like that of Skaftafell (Iceland), form excellent chronosequences to study the development of soil ecology during soil formation. This figure shows soil food web development for a period of 120 years. The indicative value of soil biodiversity Because of its high functionality, soil biological properties have been studied for their indicative value for soil quality. Soil quality can refer to agricultural soil fertility, soil habitat suitability for species rich natural vegetation, land degradation and soil pollution. Micro-‐arthropod Taxa r ichness 30 Micro-‐arthropod Taxa richness 20 20 10 0 0 Micro-‐arthropod Shannon diversity index 2 Degraded Intermediate N ot degraded 10 3 1 0 Coventional O rganic Conventional O rganic Coventional O rganic Conventional O rganic Koiliaris (Crete) Austria Iceland Austria Iceland Figure 4. The SoilTrEC sites with gradients of land degradation and the different agricultural farming confirmed micro-arthropod diversity as soil quality indicator. Authors: Jeroen P. van Leeuwen, Daniel Moraetis, Jaap Bloem, Lia Hemerik, Taru Lehtinen, Kristín Vala Ragnarsdóttir, Guðrún Gísladótti, Jeffrey Newton, Georg Lair, Peter C. de Ruiter. For more information visit SoilTrEC website: www.soiltrec.eu Contact us: Prof. Steven Banwart, SoilTrEC Project Coordinator, University of Sheffield. Email: [email protected]
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