Ecosystem susceptibility to invasion by nonnative species is poorly understood, but evidence
is increasing that spatial and temporal variability in resources has large‐scale effects. We …

Bromus tectorum is a winter annual grass that has become extensively naturalized in western
North America. Its seeds are usually at least conditionally dormant at dispersal and lose …

Advances in seed biology include progress in understanding the ecological significance of
seed dormancy mechanisms. This knowledge is being used to make more accurate …

Methods Fully ripened seeds were collected from 15 populations of mountain big sagebrush
in autumn 1986. Collection sites represented six states and a range of habitats from 1000 to …

Pathogen spillover occurs when disease levels for a given population are driven by transmission
from a reservoir species that carries a high pathogen load. Pathogen spillover is widely …

Bromus tectorum L. (cheatgrass) is an invasive winter annual whose seeds lose dormancy
through dry afterripening. In this paper a thermal after-ripening time model for simulating seed …

Semiarid gypsum karstlands in north central Mexico are characterized by a mosaic of shrubland
and endemic gypsophile grassland community types. Proximal physical factors affecting …

Hydrothermal time (HTT) describes progress toward seed germination under various
combinations of incubation water potential ( ) and temperature (T). To examine changes in HTT …

Cheatgrass (Bromus tectorum) is an invasive weed in western North America found primarily
growing at elevations less than 2200 m. We asked whether cheatgrass is capable of …

Seed collections from 72 rubber rabbitbrush populations occupying a range of habitats in
western North America were incubated at 3 C in the laboratory. Collections from warm desert …