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Titel |
Factors responsible for the patchy distribution of natural soil water repellency in Mediterranean semiarid forest |
VerfasserIn |
E. Lozano, P. Jiménez-Pinilla, J. Mataix-Solera, J. A. González-Pérez, F. García-Orenes, M. P. Torres, V. Arcenegui, J. Mataix-Beneyto |
Konferenz |
EGU General Assembly 2012
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 14 (2012) |
Datensatznummer |
250059256
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Zusammenfassung |
Soil water repellency (WR) is commonly observed in forest areas showing wettable and water
repellent patches with high spatial variability. This has important hydrological implications;
in semiarid areas where water supply is limited, even slight WR may play an important role
in infiltration patterns and distribution of water into the soil (Mataix-Solera et al., 2007). It
has been proposed that the origin of WR is the release of organic compounds from
different plants species and sources (due to waxes and other organic substances in
their tissues; Doerr et al., 1998). However, the relationship between WR and plants
may not always be a direct one: a group of fungi (mainly mycorrhizal fungi) and
microorganisms could be also responsible for WR. The aim of this research is to study the
relationships between WR in soils under different plant cover with selected soil
properties and the quantity of fungi and their exudates. The study area is located
in Southeast Spain, “Sierra de la Taja” near Pinoso (Alicante)), with a semiarid
Mediterranean climate (Pm=260mm). Samples were taken in September 2011,
when WR is normally strongest after summer drought. Soil samples were collected
from the first 2.5cm of the mineral A horizon at microsites beneath each of the four
most representative species (Pinus halepensis, Rosmarinus officinalis, Quercus.
rotundifolia and Cistus albidus; n=15 per specie) and 5 samples from bare soil with no
influence of any species. Different soil parameters were analyzed; water content,
soil organic mater content (SOM), pH, WR, easily extractable glomalin (EEG),
total mycelium and extractable lipids. The occurrence of WR was higher under P.
halepensis (87% of samples) and Q. rotundifolia (60% of samples). Positive significant
correlations were found between WR and SOM content for all species, with the
best correlations for Pinus and Quercus (r=0.855**, r= 0.934** respectively). In
addition, negative significant correlations were found between WR and pH and
between SOM and pH for all except for Q. rotundifolia. However, the negative
correlation found between pH and persistence of WR seems to be related to soil organic
matter (SOM) content for all vegetal species. Glomalin exudates from arbuscular
mycorrhizal fungi in soil revealed significant differences between species. However, the
first results do not point to a direct relationship between EEG content and WR
but to soil mineralogy or certain components within SOM pool i.e. litter debris
degradation products or specific components within the glomalin extract, as main factors
affecting soil WR. Nonetheless, since some samples with the same SOM content
(including some under the same vegetation cover) showed different WR persistence,
complementary research including a more detailed characterization of most soil
functional fractions (SOM and clays) is planned in order to elucidat the main factors
influencing the presence and persistence of WR in soils under Mediterranean semiarid
forest.
Keywords: Water repellency, hydrophobicity, easily extractable glomalin, mycelium,
arbuscular mycorrhizal fungi.
References:
Mataix-Solera J., Arcenegui, V., Guerrero C., Mayoral A. M., Morales J., González I.,
García-Orenes F. and Gómez I. 2007. Water repellency under different species in a
calcareous forest soil in a semiarid Mediterranean environment. Hydrological Processes: 58:
1254-1259
Doerr, S.H. 1998. On standardizing the “water drop penetration time” and the
“molarity of an ethanol droplet” techniques to classify soil hydrophobicity. A case study
using medium textured soils. Earth Surface Processes and Landforms 23: 663-668 |
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