Document Detail

Favorable fragmentation: river reservoirs can impede downstream expansion of riparian weeds.
MedLine Citation:
PMID:  20945766     Owner:  NLM     Status:  MEDLINE    
River valleys represent biologically rich corridors characterized by natural disturbances that create moist and barren sites suitable for colonization by native riparian plants, and also by weeds. Dams and reservoirs interrupt the longitudinal corridors and we hypothesized that this could restrict downstream weed expansion. To consider this "reservoir impediment" hypothesis we assessed the occurrences and abundances of weeds along a 315-km river valley corridor that commenced with an unimpounded reach of the Snake River and extended through Brownlee, Oxbow, and Hells Canyon reservoirs and dams, and downstream along the Snake River. Sampling along 206 belt transects with 3610 quadrats revealed 16 noxious and four invasive weed species. Ten weeds were upland plants, with Canada thistle (Cirsium arvense) restricted to the upstream reaches, where field morning glory (Convolvulus arvensis) was also more common. In contrast, St. John's wort (Hypericum perforatum) was more abundant below the dams, and medusahead wildrye (Taeniatherum caput-medusae) occurred primarily along the reservoirs. All seven riparian species were abundant in the upstream zones but sparse or absent below the dams. This pattern was observed for the facultative riparian species, poison hemlock (Conium maculatum) and perennial pepperweed (Lepidium latifolium), the obligate riparian, yellow nut sedge (Cyperus esculentus), the invasive perennial, reed canary grass (Phalaris arundinacea), and three invasive riparian trees, Russian olive (Elaeagnus angustifolia), false indigo (Amorpha fruticosa), and tamarisk (Tamarix spp.). The hydrophyte purple loosestrife (Lythrum salicaria) was also restricted to the upstream zone. These longitudinal patterns indicate that the reservoirs have impeded the downstream expansion of riparian weeds, and this may especially result from the repetitive draw-down and refilling of Brownlee Reservoir that imposes a lethal combination of drought and flood stress. The dams and reservoirs may also interrupt hydrochory, the downstream flow of seeds and clonal fragments. We thus conclude that with some operational patterns, dams and reservoirs can impede the downstream expansion of riparian weeds.
Stewart B Rood; Jeffrey H Braatne; Lori A Goater
Related Documents :
20673966 - Long-term monitoring (1960-2008) of the river-sediment transport in the red river water...
16191766 - Geochemical signatures (c, n, delta13c, delta15n, metals) of suspended matter in the ri...
2326626 - Pollution by the fungicide pentachloronitrobenzene in an intensive farming area in japan.
20416946 - Winter to spring variations of chromophoric dissolved organic matter in a temperate est...
22328856 - Two new species of quedius stephens, subgenus raphirus stephens from yunnan, southwest ...
10394856 - In vitro susceptibility of opportunistic fusarium spp. to essential oils.
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ecological applications : a publication of the Ecological Society of America     Volume:  20     ISSN:  1051-0761     ISO Abbreviation:  Ecol Appl     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-10-15     Completed Date:  2010-11-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9889808     Medline TA:  Ecol Appl     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1664-77     Citation Subset:  IM    
Department of Biological Sciences, University of Lethbridge, Alberta T1K 3M4, Canada.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Conservation of Natural Resources*
Environmental Monitoring
Plants / classification*
Water Movements

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Effect of forest clear-cutting on subtropical bryophyte communities in waterfalls, on dripping walls...
Next Document:  Floral and nesting resources, habitat structure, and fire influence bee distribution across an open-...