Phytolith pool in soils affected by different land use in southeastern pampean region, Argentina

Phytoliths are important plant microfossils, but also relevant components of the clastic fraction of the soils. The phytolith pool present in soils not only depends on plant phytolith production but also on taphonomical soil processes. In the southeastern Pampean Plains, Argentina, where typical Argiudolls dominate, intense agricultural and livestock activities are carried on. These managements affect both plant diversity and soil properties, which in turn, may influence on the soil phytolith assemblages. The aim of this study was to describe and compare the phytolith assemblages of soils under different land uses and to compare them with the current phytolith production of plants. Three plots with different land uses were selected (pasture, cultivated field, and nature reserve). Phytoliths were extracted from plants and dung by calcination. Soil phytoliths were extracted using a centrifugation technique and the total soil phytolith content was determined. Phytolith production was higher in crops than in non-crop species. Differences in the distribution and content of phytoliths were found in soils under different land uses and no close relationship was observed between current vegetation and soil phytoliths. Soils in the nature reserve, where living plants are trace phytolith producers, had the highest phytolith content values. Cropland soils had the lowest phytolith content and the highest degradation state. The results showed that land use leads to differences in phytolith content in soils. Agricultural management modifies the typical pattern of phytolith distribution along profiles and reduces the total content of phytoliths, whereas nature plots with plant invasion modify the accumulation of organic debris in soils and promote a higher preservation of phytoliths. Finally, dung introduces both new and degraded phytoliths into soils.