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]