CONICET | Buscador de Institutos y Recursos Humanos

Abstract The objective of this study was to assess the formation, distribution, and physico-chemical properties of litter in two types of shrubs patches, featured by the dominant species (Atriplex lampa and Prosopis alpataco). These species are important components of the Monte Phytogeographic Province. The surface layers of the shrubs-steppe have been classified into four soil condition classes using attributes that are easily observable in the field. These classes provide an estimate of litter special patterns and of potential dry matter production. Litter differs greatly in chemical content. The P. alpataco patch presents higher quality in organic matter, based in its elemental composition of carbon, nitrogen, and phosphorus. The patterns of the lignin studied in both patches were different. The sum of phenolic oxidation species was higher in summer for P. alpataco than in A. lampa, indicating higher contents in lignin components in the former and a slight oxidation in the latter. The strongest peaks in 13C NMR spectra are present in the rank polysaccharides and sharper aliphatic structures. Seasonal differences between patches correlate to the results obtained in polysaccharides and lignin and might be ascribes to the high mineralization of the former. The results of this study indicate that the shrub structure in terms of patch types and patch dynamics controls the conten, distribution, and composition of litter materials an has a major impact on litter descomposition. Thus the formation, distribution, and function of litter in shrubs-steppe soils can be studied through the structural characterization of patches and classes of soil surface conditions. Keywords: carbon types, litter decomposition, litter spatial patterns, patch patterns, patch types

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