SummarySoil organic matter (SOM) is an important factor in ecosystem stability and productivity. This is especially thecase for Mediterranean soils suffering from the impact of humans and degradation as well as harsh climaticconditions. We used the carbon (C) exchange resulting from C3-C4 and C4-C3 vegetation change under fieldconditions combined with incubations under controlled conditions to evaluate the turnover and availability ofsoil organic C under different land-uses. The 40-year succession of Hyparrenia hirta L. (C4 photosynthesis)after more than 85 years of olive (Olea europaea L.) tree (C3 photosynthesis) growth led to the exchange of54% of soil organic C from C3 to C4 forms. In contrast, 21 years of vine (Vitis vinifera L.) growing after H.hirta decreased the organic C content to 57%. Considering this exchange and decrease as well as the periodsafter the land-use changes, we calculated the mean residence time (MRT) of soil C of different ages. TheMRT of C under grassland dominated by H. hirta was about 19 years, but was 180 years under the vineyard.The rates of C accumulation under the H. hirta grassland were about 0.36MgC ha−1 year−1. In contrast, therates of C losses after conversion from natural grassland to a vineyard were 1.8 times greater and amountedto 0.65MgC ha−1 year−1. We conclude that changes of land use from natural Mediterranean grassland to avineyard lead to very large C losses that cannot be compensated for over the same periods.
|Numero di pagine||11|
|Rivista||European Journal of Soil Science|
|Stato di pubblicazione||Published - 2013|
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