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Environmental resource gradients affect plant establishment during invasive weed management and ecological restoration. We investigated how hydrology and nitrogen (N) availability influence establishment of native and invasive species along a dry-wet gradient. We hypothesized that 1) emergence and growth would be higher in subirrigaated environments than in saturated or dry environments; 2) annuals and invasive exotics would respond more to N availability than late-successional perennials; and 3) N effects would be greatest in subirrigated environments. In the greenhouse, seedling emergence was uniform across dry to subirrigated pots for upland species and across subirrigated to saturated, but not flooded, pots for riparian species. Seedling biomass was greatest in subirrigated environments. Seedling emergence in the field was at or near zero for most species in subirrigated sites. In the greenhouse, biomass increased with N availability, and responses to N were greatest in subirrigated pots. In both experiments, the upland invasive, spotted knapweed (Centaurea maculosa), responded more to N availability than bluebunch wheatgrass (Agropyron spicatum). However, such differences were not found for the riparian species, possibly due to low emergence. Possible explanations for low emergence in subirrigated field sites include predation by small rodents, which were more active in the transition than upland or wetland areas. Establishment of spotted knapweed and Canada thistle (Cirsium arvense) in riparian sites was limited by poor germination and seedling survival. Once established, growth was good in subirrigated environments, indicating that weeds may invade riparian sites in spite of poor initial establishment, which suggests caution when contemplating ecological restoration practices that increase N availability. [ABSTRACT FROM AUTHOR]