Formation,Distribution, and Physicochemical Properties of Plant Litter in Shrub Patches of Northeastern Patagonia

The objective of this study was to assess the formation, distribution, and physicochemical properties of litter in two types of shrub 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 shrub-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 spatial patterns and of potential dry matter production. Litter differs greatly in chemical content. The P. alpataco patch presents higher quality in organic matter , based on its elemental composition of carbon , nitrogen , and phosphorus . The patterns of the lignin studied in both patches were different . The sum of phenolic oxida tion species was higher in summer for P. alpataco than in A. lampa, indicating higher contents of lignin components in the former and a slight oxidation in the latter . The strongest peaks in 1 3 C NMR spectra are present in the rank of poly saccharides and sharper aliphatic structures . Seasonal differences between patches correlate to the results obtained in polysaccharides and lignin and might be ascribed 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 content , distribution , and composition of litter materials and has a major impact on litter decomposition . Thus the formation , distribution , and function of litter in shrub steppe soils can be studied through the structural characterization of patches and classes of soil surface conditions.