The recent expansion of the reed Phragmites australis in western Atlantic salt marshes has become a conservation concern. Historically, Phragmites was restricted to the terrestrial border of marshes, but now it aggressively invades lower elevations. To explore factors influencing this expansion, we examined (1) the effects of physical factors and competitive interactions on the performance of Phragmites and (2) the role of clonal integration on the ability of Phragmites to invade low marsh habitats.We transplanted Phragmites into vegetation along an elevation gradient, with and without neighboring plants. Phragmites died when transplanted to the lowest marsh zone but survived and expanded in higher marsh zones. This suggests that the low oxygen availability characteristic of waterlogged soils limits Phragmites growth in the low marsh. Neighboring vegetation reduced Phragmites growth in all zones, and severing Phragmites rhizomes invading the low marsh reduced the survivorship and photosynthetic rate of ramets.These results suggest that Phragmites may invade low marsh habitats by initially establishing itself in the high marsh and then expanding into lower, less favorable habitats using clonal integration. This has important implications for understanding the changing dynamics of New England salt marsh plant communities and developing management strategies for the control of Phragmites.
The recent expansion of the reed Phragmites australis in western Atlantic salt marshes has become a conservation concern. Historically, Phragmites was restricted to the terrestrial border of marshes, but now it aggressively invades lower elevations. To explore factors influencing this expansion, we examined (1) the effects of physical factors and competitive interactions on the performance of Phragmites and (2) the role of clonal integration on the ability of Phragmites to invade low marsh habitats. We transplanted Phragmites into vegetation along an elevation gradient, with and without neighboring plants. Phragmites died when transplanted to the lowest marsh zone but survived and expanded in higher marsh zones. This suggests that the low oxygen availability characteristic of waterlogged soils limits Phragmites growth in the low marsh. Neighboring vegetation reduced Phragmites growth in all zones, and severing Phragmites rhizomes invading the low marsh reduced the survivorship and photosynthetic rate of ramets. These results suggest that Phragmites may invade low marsh habitats by initially establishing itself in the high marsh and then expanding into lower, less favorable habitats using clonal integration. This has important implications for understanding the changing dynamics of New England salt marsh plant communities and developing management strategies for the control of Phragmites.
Herbivores are pervasive, yet their effects on plant fecundity are often variable. One potential source of variation in herbivore impacts results from differing feeding modes of herbivores. We examined the relative importance of inflorescence-feeding insects versus large ungulates in affecting the fecundity of Balsamorhiza sagittata (Asteraceae), a dominant native perennial forb in western Montana, USA. We quantified these effects across four sites that varied in elevation to determine how consistent herbivore impacts were across these divergent sites. Insect herbivores were present in flower heads at all sites but they significantly depressed plant fecundity at two of the four sites. At the two sites where herbivore suppression had significant effects, this treatment let to 1.6 and 3.4-fold increases in seed production, respectively. In contrast, across all sites ungulates had minimal impacts on balsamroot flower and seed production. Seed addition experiments revealed that at some sites and in some years B. sagittata is seedlimited, as there was a positive relationship between seed input and seedling recruitment. Thus, reductions in seed production from heavy insect herbivory may limit balsamroot recruitment in some locations.Overall, results show that inconspicuous insects have stronger effects on balsamroot fecundity than do mammalian herbivores, but the magnitude of negative impacts at both the individual and populationlevel vary by site.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.