Author
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De Queiroz, Tara |
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Submitted to: Plant Species Biology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/2/2010 Publication Date: 9/15/2010 Citation: Forbis, T.A. 2010. Germination Phenology Of Some Great Basin Native Annual Forb Species. Plant Species Biology. 25(3):221-230. Interpretive Summary: Great Basin native plant communities are being replaced by the annual invasive cheatgrass (Bromus tectorum). Cheatgrass can germinate in spring of fall. Although perennials dominate these communities, native annuals are present in many sites. Germination timing is often an important predictor of competitive interactions, and might determine whether the use of annual species in restoration efforts will be successful. I used a laboratory experiment to determine whether a suite of native annuals exhibit winter or spring annual germination syndromes. Seeds of Amsinckia menziesii var. intermedia, Amsinckia tesselata, Blepharipappus scaber, Descurainia pinnata, Eriastrum sparsiflorum, Lappula occidentalis, Mentzelia veatchiana, and Plagiobothrys tenellus were tested for dormancy, and for responsiveness to light, wet cold treatment, and hot dry treatment. Species that would be expected to be most similar to cheatgrass are those that have no requirement for cold stratification, and are therefore likely to germinate under fall or winter conditions. Species that clearly meet this criterion in this lab study were Amsinckia menziesii var. intermedia, Amsinckia tesselata, Descurainia pinnata and Lappula occidentalis. In contrast, Blepharipappus scaber, Eriastrum sparsiflorum, Mentzelia veatchiana, and Plagiobothrys tenellus had their highest germination after cold stratification and would be expected to be spring germinators. Blepharipappus scaber was not coaxed out of dormancy to a great degree by any of the treatments I applied and may exhibit cue-nonresponsive dormancy. Field seed burial experiments, as well as experiments examining competitive ability of these annuals versus cheatgrass, will further inform us about their potential for success in restoration seedings. Technical Abstract: Great Basin native plant communities are being replaced by the annual invasive cheatgrass (Bromus tectorum). Cheatgrass exhibits a germination syndrome that is characteristic of facultative winter annuals. Although perennials dominate these communities, native annuals are present in many sites. Germination timing is often an important predictor of competitive interactions, and might determine whether the use of annual species in restoration efforts will be successful. I used a laboratory experiment to determine whether a suite of native annuals exhibit winter or spring annual germination syndromes. Seeds of Amsinckia menziesii var. intermedia, Amsinckia tesselata, Blepharipappus scaber, Descurainia pinnata, Eriastrum sparsiflorum, Lappula occidentalis, Mentzelia veatchiana, and Plagiobothrys tenellus were tested for dormancy, and for responsiveness to light, cold stratification, and dry after-ripening. Species that would be expected to be most similar to cheatgrass are those that have no requirement for cold stratification, and are therefore likely to germinate under fall or winter conditions. Species that clearly meet this criterion in this lab study were Amsinckia menziesii var. intermedia, Amsinckia tesselata, Descurainia pinnata and Lappula occidentalis. In contrast, Blepharipappus scaber, Eriastrum sparsiflorum, Mentzelia veatchiana, and Plagiobothrys tenellus had their highest germination after cold stratification and would be expected to be spring germinators. Blepharipappus scaber was not coaxed out of dormancy to a great degree by any of the treatments I applied and may exhibit cue-nonresponsive dormancy. Field seed burial experiments, as well as experiments examining competitive ability of these annuals versus cheatgrass, will further inform us about their potential for success in restoration seedings. |
