Exploring short-term leaf-litter decomposition dynamics in a Mediterranean ecosystem: dependence on litter type and site conditions
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Plant litter decomposition plays an important role in the storage of soil organic matter in terrestrial ecosystems. Conversion of native vegetation to agricultural lands and subsequent land abandonment can lead to shifts in canopy structure, and consequently influence decomposition dynamics by alterations in soil temperature and moisture conditions, solar radiation exposure, and soil erosion patterns. This study was conducted to assess which parameters were more closely related to short-term decomposition dynamics of two predominant Mediterranean leaf litter types.
Using the litterbag technique, we incubated leaf litter of Pinus halepensis and Rosmarinus officinalis in two Mediterranean land-uses with different degree of vegetation cover (open forest, abandoned agricultural field).
Fresh local litter lost between 20 and 55% of its initial mass throughout the 20-month incubation period. Rosemary litter decomposed faster than pine litter, showing net N immobilization in the early stages of decomposition, in contrast to the net N release exhibited by pine litter. Parameters related to litter quality (N content or C:N) or land-use/site conditions (ash content, an index of soil deposition on litter) were found to explain the cross-site variability in mass loss rates for rosemary and Aleppo pine litter, respectively.
The results from this study suggest that decomposition drivers may differ depending on litter type in this Mediterranean ecosystem. While rosemary litter was degraded mainly by microbial activity, decomposition of pine litter was likely driven primarily by abiotic processes like soil erosion.
KeywordsCarbon cycle Litter decomposition Mediterranean ecosystem N immobilization Soil erosion Vegetation structure
This research was supported with funds provided by the Spanish CICYT (ERHIBAC project, GGL2004-03179 BTE; PROBASE project, CGL2006-11619 HID), the SÉNECA Foundation of the Murcia Regional Government (03027/PI/05; 08757/PI/08), and the Spanish Ministerio de Medio Ambiente (RESEL project). We thank Javier Melgares, the owner of the experimental area, and Sebastian for their great interest in helping us during our work, and the members of the Soil and Water Conservation Department, who helped us in the lab and field work. The authors also thank Marta Goberna and Nacho Querejeta for helpful comments on the manuscript, and Gonzalo Barberá for his useful advice with statistical analyses. The State Agency of Meteorology (AEMET) is also acknowledged for providing some rainfall data.
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