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| Titel |
Modelling spatiotemporal distribution patterns of earthworms in order to indicate hydrological soil processes |
| VerfasserIn |
Juliane Palm, Julian Klaus, Loes van Schaik, Erwin Zehe, Boris Schröder |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041199
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| Zusammenfassung |
| Soils provide central ecosystem functions in recycling nutrients, detoxifying harmful
chemicals as well as regulating microclimate and local hydrological processes. The internal
regulation of these functions and therefore the development of healthy and fertile soils mainly
depend on the functional diversity of plants and animals. Soil organisms drive essential
processes such as litter decomposition, nutrient cycling, water dynamics, and soil structure
formation. Disturbances by different soil management practices (e.g., soil tillage,
fertilization, pesticide application) affect the distribution and abundance of soil organisms and
hence influence regulating processes. The strong relationship between environmental
conditions and soil organisms gives us the opportunity to link spatiotemporal distribution
patterns of indicator species with the potential provision of essential soil processes on
different scales.
Earthworms are key organisms for soil function and affect, among other things, water
dynamics and solute transport in soils. Through their burrowing activity, earthworms increase
the number of macropores by building semi-permanent burrow systems. In the
unsaturated zone, earthworm burrows act as preferential flow pathways and affect water
infiltration, surface-, subsurface- and matrix flow as well as the transport of water and
solutes into deeper soil layers. Thereby different ecological earthworm types have
different importance. Deep burrowing anecic earthworm species (e.g., Lumbricus
terrestris) affect the vertical flow and thus increase the risk of potential contamination of
ground water with agrochemicals. In contrast, horizontal burrowing endogeic (e.g.,
Aporrectodea caliginosa) and epigeic species (e.g., Lumbricus rubellus) increase water
conductivity and the diffuse distribution of water and solutes in the upper soil layers. The
question which processes are more relevant is pivotal for soil management and
risk assessment. Thus, finding relevant environmental predictors which explain the
distribution and dynamics of different ecological earthworm types can help us to
understand where or when these processes are relevant in the landscape. Therefore, we
develop species distribution models which are a useful tool to predict spatiotemporal
distributions of earthworm occurrence and abundance under changing environmental
conditions. On field scale, geostatistical distribution maps have shown that the spatial
distribution of earthworms depends on soil parameters such as food supply, soil
moisture, bulk density but with different patterns for earthworm stages (adult, juvenile)
and ecological types (anecic, endogeic, epigeic). On landscape scales, earthworm
distribution seems to be strongly controlled by management/disturbance-related
factors.
Our study shows different modelling approaches for predicting distribution patterns of
earthworms in the Weiherbach area, an agricultural site in Kraichtal (Baden-Württemberg,
Germany). We carried out field studies on arable fields differing in soil management practices
(conventional, conservational), soil properties (organic matter content, texture, soil moisture),
and topography (slope, elevation) in order to identify predictors for earthworm occurrence,
abundance and biomass. Our earthworm distribution models consider all ecological groups as
well as different life stages, accounting for the fact that the activity of juveniles is sometimes
different from those of adults. Within our BIOPORE-project it is our final goal to couple our
distribution models with population dynamic models and a preferential flow model
to an integrated ecohydrological model to analyse feedbacks between earthworm
engineering and transport characteristics affecting the functioning of (agro-) ecosystems. |
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