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Emergence of the Introduced Grass Agropyron cristatum and the Native Grass Bouteloua gracilis in a Mixed-grass Prairie Restoration
Prairie restoration at the northern edge of the Great Plains can be frustrated by previously established non-native perennial grasses. We compared the emergence of a widely introduced grass, Agropyron cristatum, and a common native grass, Bouteloua gracilis, in a 4-year-old field experiment in which the Agropyron-dominated vegetation had either been left intact or treated annually with herbicide. This was done at two levels of water supply, reflecting conditions expected in wet and dry years, to examine the effects of among-year variability in precipitation. Water addition significantly increased the emergence of both surface-sown and buried (1 cm deep) seeds. Herbicide treatment of neighbors did not increase the...
These data were compiled as part of a field and growth chamber study of the establishment of Salsola tragus (Russian thistle), an invasive non-native annual plant in North America. Field work was conducted at Petrified Forest National Park, Arizona in 2015 and 2016 and the growth chamber study was conducted in 2016. The data represent field measurements of Salsola germination and growth (cover) and sediment movement at two field sites, one a stabilized sand sheet (SS) and the other on the ridge of a sand dune (SD). The data also represent a growth chamber assessment of the soil and litter seed bank from representative samples take at the two field sites.
Experiments were conducted to assess the influences of granivores on the seed bank in sagebrush-steppe. Rodent and/or ant exclosures were established at two distances from five harvester ant mounds. Monthly soil samples were collected from the exclosures, and from open access areas at two distances to ascertain changes in the seed bank. Seed dish experiments were conducted monthly to establish a maximum seed removal rate. Rodents were trapped monthly. More seeds were recovered from rodent exclosures than from ant exclosures. Seed banks changed temporally and spatially, with more seeds recovered in September and at 6 m from mounds. Rodents removed seeds more rapidly from seed dishes than did ants. Ants removed more...
In annual plants, increased competitive advantage has often been attributed to rapid germination and early establishment. In contrast, many annual species exhibit some degree of delayed germination (i.e., seed dormancy) that results in the formation of age structure within the seed population. Delayed germination can be an effective bet-hedging strategy in variable or unpredictable environments as a seed bank can buffer against years with reproductive failures and reduce the probability of local extinction. However, there has been little consideration of the direct effects of aging within the seed pool although the potential demographic costs of such a strategy (e.g., mortality in the seed bank or delayed reproduction)...