Seed bank dynamics in a temperate zone deciduous forest

Laura Allison Hyatt, University of Pennsylvania

Abstract

The soil of many ecosystems contains persistent, germinable seeds that can live for years, decades, and possibly even centuries. Variable composition and density of the seed bank is widely documented among and within communities. Although this variation is widely documented, empirically and experimentally derived explanations are lacking. The interplay of sources of gain and loss in the seed bank of a temperate zone deciduous forest were investigated to illuminate the causes of variation in seed bank density and composition. A novel technique was used to examine the influence of aboveground vegetation on sources of gain and loss during seed bank formation. Experimental manipulations using artificial seed banks and transplanting natural seed banks to disturbances of different qualities helped to dissect causes of seed mortality and the emergence of seeds from the seed bank under simulated disturbance conditions. Finally, simulation modelling generated artificial seed banks using natural rates of seed survival and deposition and isolated potentially important sources of gain and loss. It was shown that large numbers of seeds survive in situ, and that many of these seeds are likely to remain ungerminated. Seed survival was demonstrated to be spatially variable, and linked to aboveground landscape features. Variation in seed germinability within the seed bank was shown to have strong influences on seed bank function under disturbance conditions, not detectable when censusing the seed bank under greenhouse conditions. Under the simulation model, seed bank turnover rate was not readily predictable by only examining the relationship between seed bank input and size, and was mainly sensitive to changes in non-vertebrate causes of seed mortality. The results of these studies show that variation in seed bank composition and density is the result of complex interactions between features of the landscape, seed input and survival. Future investigations of the causes of seed bank variation will require dissection of seed bank dynamics into component sources of gain and loss and close examination of individual species' dynamics.

Subject Area

Ecology|Forestry

Recommended Citation

Hyatt, Laura Allison, "Seed bank dynamics in a temperate zone deciduous forest" (1996). Dissertations available from ProQuest. AAI9627937.
https://repository.upenn.edu/dissertations/AAI9627937

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