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Comparative dispersion of walnut and sycamore trees

Nan Ash, Anna Dixon, Cameron Meehan, and Hope Palalay


Walnut and sycamore have different dispersal strategies.  Walnut produces large seeds surrounded by a thick husk; these seeds are animal-dispersed.  Sycamore produces compact balls containing hundreds of feathered seeds; these seeds are wind-dispersed.  We researched the comparative distribution of walnut and sycamore trees in an old field undergoing secondary succession.  


We hypothesized that young walnut trees would be located close to source walnut trees because of their limited dispersal mechanism.  In comparison, young sycamore trees would be distributed on a more widespread basis and farther from source sycamore trees.


We conducted our research in the old field within the K2 loop trail (Creekside Trail) in the DePauw Nature Park.  We set up three plots; each plot was 30 x 10 meters in size.  Within each plot, we counted the number of source trees and young trees.  We cut down smaller trees and used an increment borer to core larger trees to estimate their age.


The abundance of young walnut trees declined as distance from a source walnut tree increased.  The abundance of young sycamore trees was unaffected by distance from a source sycamore trees.