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New Mexico State University (2020)

Legacies of Fire and Presence of Woody Vegetation on Soil Seed Banks of Four North American Desert Systems

Hosna, Rachel Kathryn

Titre : Legacies of Fire and Presence of Woody Vegetation on Soil Seed Banks of Four North American Desert Systems

Auteur : Hosna, Rachel Kathryn

Université de soutenance : New Mexico State University

Grade : Master of Science (MS) 2020

Description
Dryland plant community recovery after wildfire can be variable, and legacies of these fires can extend not only to the aboveground plant community but also to the soil seed banks. These viable seeds within the soil can provide insight into both the history of a system and the in-situ propagules available to colonize the aboveground community. Even with this fundamental role in structuring future plant communities, the degree to which dryland soil seed banks are impacted by fire and their subsequent post-fire succession is poorly understood. To address this knowledge gap, we used a time-since-fire approach to investigate changes in soil seed bank communities approximately 15 and 30 years after fire (relative to unburned sites) and determine the influence of microsites (e.g., shrub and interspace) on seed bank composition. We looked at changes in soil seed bank densities, species richness and composition across four North American deserts including two cold deserts (Colorado Plateau and Great Basin) and two warm deserts (Chihuahuan and Sonoran). Soil samples were collected in the field and we used a greenhouse emergence technique to quantify the seed bank. Our results indicate that overall seed bank characteristics diverged between warm and cold deserts, such that warm deserts had seed banks dominated by annuals while cold deserts had seed banks with great proportions of perennial species. Fire significantly altered species composition even 30 years after fire but only in cold deserts. Shrub and interspace microsites had no observed influence on seed bank species composition in any desert, however, species richness was greater under shrubs in both warm deserts. Non-native species were present in the seed banks of all deserts, and some were highly correlated with burned plots. This suggests some degree of vulnerability to future disturbances despite the presence of native species in both burned and unburned seed banks.

Présentation (NMSU Library)

Aperçu document (ProQuest)

Page publiée le 4 novembre 2020