Cordgrasses in the genus Spartina are good examples of ecosystem engineers that modify habitat structure in estuaries throughout the world. In San Francisco Bay, California, USA, marshes containing native California cordgrass (Spartina foliosa) are being invaded by a hybrid (S. alterniflora  S. foliosa) formed after introduction of S. alterniflora. This study compared vegetation, sediment structure, and infaunal invertebrates in native and invaded marshes. We hypothesized that differences in the physical structure between S. foliosa and hybrid Spartina would be reflected in differences in density, biomass, diversity, and taxonomic composition of infauna. Hybrid Spartina modifies habitat structure more than S. foliosa by producing taller stems, and greater plant biomass both above-and belowground while occupying a much wider tidal range, thereby transforming open mudflats to a vegetated habitat. In general, S. foliosa areas contained significantly higher densities of benthic infauna than adjacent mudflats, while hybrid Spartina areas never contained greater infaunal densities than mudflats. This is because S. foliosa produces a moderate level of structure that can facilitate benthic invertebrates, whereas hybrid Spartina produces so much structure, particularly belowground, that it actually excludes invertebrates. Therefore, we suggest that these two closely related species both act as ecosystem engineers, but with opposing effects on invertebrate communities.

Studies examining the impacts of introduced species on food webs often focus on the topdown effects of introduced predators. However, marine and estuarine systems have been invaded by plants that have the potential to alter carbon and nitrogen sources available to consumers. In San Francisco Bay, California, USA, hybridized cordgrass Spartina alterniflora 9 foliosa is adding C 4 carbon biomass to this system. We used natural abundances of stable isotopes of carbon and nitrogen to examine whether infaunal and epifaunal food webs reflected the large detrital input from hybrid Spartina. We compared stable isotope signatures among macrofaunal invertebrate consumers collected in hybrid Spartina, native S. foliosa, or unvegetated mudflats. We found no additional shift towards hybrid Spartina in hybrid areas. Structural changes brought about by an invasive ecosystem engineer, specifically increased biomass and detrital inputs, do not necessarily result in its increased incorporation into the food web.

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Restoration practitioners use both native and nonnative plant species for revegetation projects. Typically, when rehabilitating damaged working lands, more practitioners consider nonnative plants; while those working to restore habitat have focused on native plants. But this may be shifting. Novel ecosystems (non-analog communities) are commonly being discussed in academic circles, while practical factors such as affordability and availability of natives and the need for more drought tolerant species to accommodate climate change may be making nonnative species attractive to land managers. To better understand the current use of nonnatives for revegetation, we surveyed 192 California restoration stakeholders who worked in a variety of habitats. A large portion (42%) of them considered nonnatives for their projects, and of survey respondents who did not use nonnatives in vegetation rehabilitation, almost half indicated that they would consider them in the future. Across habitats, the dominant value of nonnatives for vegetation rehabilitation was found to be erosion control, and many respondents noted the high cost and unavailability of natives as important drivers of nonnative use in revegetation projects. Moreover, 37% of respondents noted they had changed their opinion or use of nonnatives in response to climate change. R evegetation is a key restoration technique to address environmental damage and increase the ecological value of degraded habitat. It involves the active re-establishment of plant communities through seeding and planting, and is undertaken usually in response to a natural disturbance, such as wildfire, or another restoration activity such as the removal of invasive plants.The design and deployment of effective revegetation requires a practitioner to set project goals, choose plant species and determine methods to reach the desired final state for a site. Species selection is important because plants can modify the physical attributes of a site, land use, community composition and invasive plant species dominance (e.g., Meli et al. 2014).Often, a fundamental requirement of a candidate plant species for revegetation is its classification as a native species. Native plants facilitate plant community trajectories toward a reference site condition, augment nutrient cycling, enhance wildlife habitat and reverse biodiversity loss (e.g., Bullock et al. 2011). In addition to the clear value of using native species to re-establish plant communities, however, there are several limitations of a natives-only requirement for revegetation projects. For example, native plant materials can be financially prohibitive (sometimes costing more than $1,000 per acre; Gornish 2015) and difficult to acquire.The high cost of plant materials is one of the leading obstacles to effective revegetation nationwide (Brodt et al. 2009;Clewell and Rieger 1997;Stanturf et al. 2001). The exclusive use of native plants

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