Estimating forest-grassland dynamics using soil phytolith assemblages and δ13C of soil organic matter

Abstract

Our objectives were to examine the relationship between contemporary vegetation and surface soil phytolith assemblages, and use phytoliths and δ13C of soil organic matter (SOM) to explore forest-grassland vegetation dynamics. We established plots within three canopy types (open, old-growth, and dense young pine) with different grass species compositions in a Pinus ponderosa forest in northern Arizona and collected vegetation data and surface (0-2 cm) and subsurface (2-7 cm) mineral soil samples. Surface soil phytolith assemblages strongly reflected vegetation at the site scale. Local vegetation patterns associated with overstory canopy types were weakly detected. Significantly fewer C₄ grass and ponderosa pine phytoliths were found in subsurface compared to surface soils. Considering all our phytolith and δ13C evidence, we suggest that C4 grasses were more widely distributed but less abundant, grasses were more spatially continuous, total grass productivity was greater, and species in the genus Koeleria and Brotnus were more common in the past.

Citation

Kerns, Becky K.; Moore, Margeret M.; Hart, Stephen C. 2001. Estimating forest-grassland dynamics using soil phytolith assemblages and δ13C of soil organic matter. Ecoscience. 8(4): 478-488.