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| Titel |
Changes of ecosystem functions in a Mediterranean shrubland exposed for eight years to prolonged summer droughts |
| VerfasserIn |
Giovanbattista de Dato, Paolo De Angelis, Carla Cesaraccio, Grazia Pellizzaro, Pierpaolo Duce, Costantino Sirca, Donatella Spano, Claus Beier |
| 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 |
250036459
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| Zusammenfassung |
| Where water is a limiting factor, like in arid and semiarid shrubland ecosystems of the
Mediterranean basin, soil moisture, strengthen by high temperatures, is the key limiting factor
controlling biogeochemical cycles. During the drought season, the unavailable water reduces
plant growth, litter decomposition and microbial soil respiration. In order to assess the
impacts of precipitation reduction on Mediterranean shrublands, a natural community has
been exposed since 2001 to prolonged summer droughts by means of mobile plastic roofs,
covering three experimental plots (20 m2) during rain events, in spring and in autumn.
Three additional plots were used as control. The vegetation reaches a maximum
height of 1.0 m and the main shrub species are Cistus monspeliensis, Helichrysum
italicum and Dorycnium pentaphyllum. Bare soil constitutes about 20% of the plot
surface.
The aim of this paper is to summarize the impact of the treatment on the plant community
structure and on ecosystem functions, after 8 years of experimentation.
A general increase of vegetation cover was observed in the whole community during the
years, as result of a natural process of recolonisation. This positive temporal pattern
was mainly observed in the control plots, whereas in the drought treatment it was
less evident and practically null in the year 2003. At species-specific level, a clear
negative effect of drought treatment was observed for C. monspeliensis. Moreover,
anticipated drought reduced C assimilation and induced an earlier change of leaf
morphology in Cistus. These effects produced the reduction of LAI and of whole plant
productivity.
The seasonal pattern of soil CO2 efflux was characterized by higher rates during the wet
vegetative season (autumn-spring) and lower rates during the dry non-vegetative season
(summer). Significant negative effects were occasionally recorded during the period with the
treatment turned on. The relation of soil respiration with temperature and soil water
content was not altered by the drier conditions, but was affected by the season.
The annual soil CO2 emissions were not significantly affected by the treatments. |
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