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Titolo:
Exotic plant invasion alters nitrogen dynamics in an arid grassland
Autore:
Evans, RD; Rimer, R; Sperry, L; Belnap, J;
Indirizzi:
Univ Arkansas, State Isotype Lab, Fayetteville, AR 72701 USA Univ Arkansas Fayetteville AR USA 72701 e Lab, Fayetteville, AR 72701 USA US Geol Survey, Moab, UT 84532 USA US Geol Survey Moab UT USA 84532US Geol Survey, Moab, UT 84532 USA
Titolo Testata:
ECOLOGICAL APPLICATIONS
fascicolo: 5, volume: 11, anno: 2001,
pagine: 1301 - 1310
SICI:
1051-0761(200110)11:5<1301:EPIAND>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
EXCHANGE RESIN BAGS; CHEATGRASS BROMUS-TECTORUM; CANYONLANDS-NATIONAL-PARK; SOIL MICROBIAL BIOMASS; SHRUB-STEPPE ECOSYSTEM; BIOLOGICAL INVASIONS; N-MINERALIZATION; SHORTGRASS STEPPE; GLOBAL CHANGE; DESERT SOILS;
Keywords:
Bromus tectorum; Canyonlands National Park, Utah, USA; denitrification enzyme activity; desert vegetation; ecosystem carbon; ecosystem nitrogen; grasslands; invasive species; litter, changes in biomass and chemistry; N mineralization; plant-available N following plant invasion; plant invasion, litter quality;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
76
Recensione:
Indirizzi per estratti:
Indirizzo: Evans, RD Univ Arkansas, State Isotype Lab, Fayetteville, AR 72701 USA Univ Arkansas Fayetteville AR USA 72701 etteville, AR 72701 USA
Citazione:
R.D. Evans et al., "Exotic plant invasion alters nitrogen dynamics in an arid grassland", ECOL APPL, 11(5), 2001, pp. 1301-1310

Abstract

The introduction of normative plant species may decrease ecosystem stability by altering the availability of nitrogen (N) for plant growth. Invasive species can impact N availability by changing litter quantity and quality, rates of N-2-fixation, or rates of N loss. We quantified the effects of invasion by the annual grass Bromus tectorum on N cycling in an arid grasslandon the Colorado Plateau (USA). The invasion occurred in 1994 in two community types in an undisturbed grassland. This natural experiment allowed us to measure the immediate responses following invasion without the confounding effects of previous disturbance. Litter biomass and the C:N and lignin:N ratios were measured to determine the effects on litter dynamics. Long-termsoil incubations (415 d) were used to measure potential microbial respiration and net N mineralization. Plant-available N was quantified for two years in situ with ion-exchange resin bags, and potential changes in rates of gaseous N loss were estimated by measuring denitrification enzyme activity. Bromus invasion significantly increased litter biomass, and Bromus litter had significantly greater C:N and lignin:N ratios than did native species. The change in litter quantity and chemistry decreased potential rates of netN mineralization in sites with Bromus by decreasing nitrogen available formicrobial activity. Inorganic N was 50% lower on Hilaria sites with Bromusduring the spring of 1997, but no differences were observed during 1998. The contrasting differences between years are likely due to moisture availability; spring precipitation was 15% greater than average during 1997, but 52% below average during spring of 1998. Bromus may cause a short-term decrease in N loss by decreasing substrate availability and denitrification enzyme activity, but N loss is likely to be greater in invaded sites in the long term because of increased fire frequency and greater N volatilization during fire. We hypothesize that the introduction of Bromus in conjunction with land-use change has established a series of positive feedbacks that will decrease N availability and alter species composition.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/04/20 alle ore 19:17:04