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| Titel |
Contour bench terrace afforestation systems in the semi-arid Israeli Negev: Effects on soil quality and geodiversity |
| VerfasserIn |
Ilan Stavi, Eli Argaman |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250103145
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| Publikation (Nr.) |
 EGU/EGU2015-2543.pdf |
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| Zusammenfassung |
| Afforestation activities are a widely accepted means of restoring degraded lands. In
the semi-arid Negev of southern Israel, extensive lands have been modified for
runoff-harvesting-based afforestation projects comprised of contour bench terrace systems
(also called shichs/shychs/shikim). However, some alarming evidence in recent years calls for
assessing the environmental impact of these afforestation lands. We assessed the effects of
contour bench terrace afforestation systems on the soil quality of the uppermost layer (0–5
cm depth) and the 0–80 cm profile, as well as on herbaceous vegetation productivity in
2-year-old and 9-year-old afforestation systems, and natural, undisturbed hillslopes. Results
showed considerable differences between the sink (contour bench terraces) and source
(inter-terrace spaces) areas of the afforested lands. Normalizing data to the relative cover of
these areas revealed similar herbaceous vegetation biomass and soil wetting front values for
the natural hillslopes (1.47 Mg ha-1 and 59.8 cm, respectively) and 9-year-old
afforestation systems (1.64 Mg ha-1 and 59.3 cm, respectively), and significantly
lower values for the 2-year-old systems (0.07 Mg ha-1 and 49.4 cm, respectively).
Unexpectedly, the opposite trend was recorded for soil hygroscopic moisture content,
which was significantly smaller for the natural hillslopes (1.7%) and 9-year-old
systems (1.9%) than the 2-year-old systems (3.2%). Soil bulk density was also
significantly affected by afforestation treatment, following the trend 2-year-old systems >
9-year-old systems > natural hillslopes (1.57, 1.55, and 1.53 Mg m-3, respectively).
Soil penetration resistance varied greatly throughout the 80-cm soil profile. There
was no significant effect of afforestation treatment on soil gravimetric moisture
content (in the spring). Overall, soil quality and herbaceous vegetation cover were
only slightly greater on the north-facing hillsides than those on the south-facing
hillsides. We concluded that the establishment of contour bench terraces increases
geodiversity on a hillslope scale, but removes the surface soil (A horizon) from extensive
areas, increases soil compaction, and decreases herbaceous vegetation production,
adversely affecting soil quality, pastoral productivity, and ecosystem functioning and
health in the short term. However, over the long term, self-restoration of small-scale
geodiversity and functioning of the geo-ecosystem is suggested to improve soil quality
and increase herbaceous vegetation productivity in these dryland forestry systems. |
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