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Titolo:
FACTORS AFFECTING REESTABLISHMENT OF AN ENDANGERED ANNUAL PLANT AT A CALIFORNIA SALT-MARSH
Autore:
PARSONS LS; ZEDLER JB;
Indirizzi:
SAN DIEGO STATE UNIV,PACIFIC ESTUARINE RES LAB SAN DIEGO CA 92182 SAN DIEGO STATE UNIV,PACIFIC ESTUARINE RES LAB SAN DIEGO CA 92182
Titolo Testata:
Ecological applications
fascicolo: 1, volume: 7, anno: 1997,
pagine: 253 - 267
SICI:
1051-0761(1997)7:1<253:FAROAE>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
REINTRODUCTION; CONSERVATION; POPULATION; SIZE;
Keywords:
COASTAL SALT MARSH; CORDYLANTHUS MARITIMUS; ENDANGERED PLANT; NITROGEN; POLLINATION; RARE PLANT; REESTABLISHMENT; REINTRODUCTION; SOUTHERN CALIFORNIA; WETLAND MANAGEMENT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
53
Recensione:
Indirizzi per estratti:
Citazione:
L.S. Parsons e J.B. Zedler, "FACTORS AFFECTING REESTABLISHMENT OF AN ENDANGERED ANNUAL PLANT AT A CALIFORNIA SALT-MARSH", Ecological applications, 7(1), 1997, pp. 253-267

Abstract

We asked whether the reproductive capacity of the endangered Cordylanthus maritimus ssp. maritimus (salt marsh bird's-beak) at Sweetwater Marsh (San Diego Bay, California) was sufficient to provide a self-sustaining population, as required by a mitigation agreement under the Endangered Species Act. After seeds were sown for three consecutive years(1990-1992) to an upper intertidal marsh where the historical population was last seen in 1987, the number of plants censused rose from approximate to 5000 in 1992 to approximate to 14 000 in 1995. The transplanted population initiated fewer seed capsules per flower (mean 0.2-0.4 capsules in 1992-1994) than the donor population (up to 0.9 capsulesin 1991). Pollen supplementation (hand-pollination) treatments increased the number of capsules by 89% in 1992, and by 52% in 1993. Abundance of pollinators appeared to be less important than the relative abundance of particular genera (i.e., Anthidium and Bombus). However, in areas where pollen supply was sufficient, nitrogen availability seemed to limit capsule set. Plant growth rates of the transplanted population compared favorably with those of the donor population (mean height 12-13 cm). At Sweetwater Marsh, larger plants produced more flowers, and aboveground dry mass of plants correlated strongly with inorganic nitrogen in the soil, which was > 71% sand. Nitrogen fertilization treatments increased plant size, foliar nitrogen content, and mean seed mass. Even though the population produced > 1.5 X 10(6) seeds from 1992 to 1994, it is not clear that C. m. maritimus will be able to sustain itself at Sweetwater Marsh. The number of plants in 1994 was < 3% of the estimated seed production in 1992-1994. Opportunities for seed germination and seedling establishment may be more limiting than reproductive capacity. The most difficult challenge to habitat managers may be maintaining ecological relationships that are dependent on external factors, i.e., pollinators, nutrient inflows, and canopy disturbances (from debris or mammals) that create the necessary openings for seedling recruitment.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 22/09/20 alle ore 03:04:35