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The fates of weed seeds
Abstract
A method for studying the fates of unprotected seeds buried in soil was developed. Using this method, studies were conducted from 1992 to 1995 at Lincoln, Nebraska, to quantify the fates of buried seeds of four weed species, Helianthus annuus, Hibiscus trionum, Rumex crispus and Sorghum bicolor. Another experiment was conducted in 1994 at Mead, Nebraska, to quantify pre-dispersal and post-dispersal predation of H. annuus seeds. Fewer than 5% of buried seeds gave rise to emerged seedlings in any year for any species. Three different dormancy patterns were exhibited by the four species. Large differences were seen in the survival patterns of buried seeds of the different species. Survival of H. annuus declined by about 20% in the first year. Virtually all such death occurred during the spring-to-autumn period. Five to 20% of H. trionum seeds died over the first winter but thereafter survival was constant. Between 55% and 80% of R. crispus died during their first year buried, mostly during the spring-to-autumn period. Eighty to 90% of S. bicolor seeds died during their first winter. The extent of decline in seed survival during the first year after burial differed for seeds buried in different years for all species except H. annuus. For seeds buried simultaneously, both the extent and temporal pattern of decline differed between the first and second years in the ground. Pre-dispersal predation of H. annuus seeds was less than 5% whereas post-dispersal predation averaged 48%. Position in the field had no clear effect upon predation. Small mammals were probably the principal predators. These studies provide estimates of the probabilities of transition through several lifecycle stages for these weeds. The estimates could be used in population dynamics models, but there are potentially serious problems with such models. I discuss the problem of temporal variation in transition probabilities for long-term population dynamics prediction and several aspects of elasticity analysis that make the results of such modelling of much less value than is commonly believed.
Subject Area
Agronomy|Ecology
Recommended Citation
Teo-Sherrell, Christopher Peter Andrew, "The fates of weed seeds" (1996). ETD collection for University of Nebraska-Lincoln. AAI9615002.
https://digitalcommons.unl.edu/dissertations/AAI9615002