Biomass allocation of three sandhills
grasses with spatially different nutrient regimes
Teresa
L. Hock and Beverly Collins
Abstract
Coastal plain Sandhills communities of South Carolina are nutrient poor, fire driven ecosystems. The post burn understory vegetation is a heterogenous mix of resprouting trees and shrubs, forbs, and bunch grasses. We asked if roots and shoots of three common sandhills grasses respond to spatially heterogeneous nutrient peaks in the soil that occur after fires. Andropogon virginicus, Sorghastrum elliottii, and Aristida stricta were grown in pots filled with sand for two years. Pots were spiked yearly with four or eight fertilizer sticks placed evenly around the pot (E4, E8) or clumped in two quarters of the pot perimeter (C4, C8). After two years, pots were sectioned into quarters; plants were harvested, partitioned into roots and shoots, dried, and weighed. With species combined, ANOVA indicated greater root biomass in the C8 than E8 treatment, but there was no significant difference between high and low nutrient quads in the heterogenous pots. This trend was also evident in Aristida when analyzed separately. However, Aristida shoot biomass did not differ between fertilizer levels or spatial patterns. Heterogeneity of soil nutrients did not affect root or shoot biomass of Andropogon, which grew well across all treatments. Sorghastrum had a greater shoot biomass in the E8 than C8 treatment. There were no differences in the root:shoot ratios of any species across all treatments. We conclude that spatially heterogenous nutrient inputs into soil after a fire will enhance root growth in Aristida, but grass roots of these three species do not track soil nutrient heterogeneity. |
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