New Jersey rush (Juncus caesariensis) COSEWIC assessment and status report: chapter 2

Executive Summary

New Jersey Rush
Juncus caesariensis

Species information

New Jersey Rush is a rhizomatous, perennial herb, 40 – 70 cm tall. The elongate leaves are narrowly cylindrical and have internal cross-walls (septa). The branched inflorescence bears clusters of non-showy, green flowers that develop into dark brown capsules. The capsules are longer than the surrounding floral parts. The culms and leaves are distinctly rough to the touch.

Distribution

Juncus caesariensis occurs on the coastal plain of New Jersey, Virginia, North Carolina and Maryland in the United States. In Canada, it is restricted to southeastern Cape Breton Island, Nova Scotia.

Habitat

In Canada, New Jersey Rush occurs primarily around the edges of bogs and fens and in small bays or coves off these same wetlands. In the United States, this species occurs in a variety of habitats including open to shaded streambanks, seepy pond margins, swales, pine barren savannas, and Chamaecyparis thyoides (Atlantic White Cedar) swamps. Changes in the hydrological regime of its habitat and canopy closure negatively impact New Jersey Rush.

Biology

New Jersey Rush is capable of both sexual (seed production) and asexual reproduction (rhizomes). Seedlings are rarely seen in the field. Plants have reappeared in habitats that had grown in with woody species and then been cleared of the woody growth. Under these circumstances, they appear to be able to persist for an unknown length of time in vegetative form.

Population sizes and trends

There are no data on long-term trends with respect to Juncus caesariensis in Nova Scotia. Very little was known about this species in Canada until the late 1980s and early 1990s.

Population sizes range from <10 to 1000 mature individuals.

Surveys over the last ten to fifteen years have led to the discovery of a total of 26 sites for this species on southeastern Cape Breton Island, Nova Scotia, with a total population estimate of 5,000 to 10,000 flowering clumps. The population at one site (17) appears to be extirpated. There are still many wetlands within the known range that have not been examined and it is very likely that more populations will be discovered here in the future.

Fieldwork conducted in 2002 found no evidence of a decline in any of the populations previously reported in the status report (Newell and Newell, 1992).

There are a number of historical records for this species in the United States suggesting that it was more widely spread in the past than it is today (Schuyler, 1990).

Limiting factors and threats

New Jersey Rush is sensitive to changes in its hydrological regime such as drainage or prolonged flooding. It would therefore be affected by road construction or wetland drainage or infilling for cottage/house construction. Logging also may affect drainage patterns in the vicinity of Juncus caesariensispopulations. All of these threats are very real possibilities on southeastern Cape Breton Island. Coastal and near coastal property in Nova Scotia is considered prime real estate. Home, cottage and road construction is therefore on the increase in these areas. Logging is a constant concern.

There has been an increase in all-terrain vehicle activity on some of the wetlands supporting New Jersey Rush in Nova Scotia, since the early 1990s. This does not appear to be negatively impacting this species at this point in time. This is an activity that needs to be monitored, however.  ATV activity on some of these wetlands will ultimately reach a level that will negatively impact this species through destruction of plants and seed banks.

New Jersey Rush is threatened by natural succession as it does not compete well with woody species.

Special significance of the species

Juncus caesariensis is a member of the Atlantic Coastal Plain Flora. The Nova Scotia populations are at the northern limit of the species’ range and are disjunct from the more southerly populations in the United States. As such, they may be genetically distinct from them. This is significant in terms of survival of the species in the face of future environmental changes such as global warming. This species is globally rare and the Nova Scotia populations make up a significant proportion of total number of plants in existence.

Existing protection or other status designations

Juncus caesariensis has been designated nationally (COSEWIC, 1992) as a species of Special Concern. Provincially, it is listed as vulnerable under the Nova Scotia Endangered Species Act. Globally, it has a G2 (imperiled) ranking. State and provincial rankings are as follows: Maryland (S1; critically imperiled), New Jersey (S2, imperiled), North Carolina (S1), Virginia (S2), Nova Scotia (S1S2, imperiled to critically imperiled) (NatureServe, 2003).

Under the Nova Scotia Department of Natural Resources general status ranking system, it is tabulated as a red-listed species (a species known to be, or is thought to be at risk).

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed  under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Definitions (after May 2004)

Species
Any indigenous species, subspecies, variety, or geographically or genetically distinct population of wild fauna and flora..

Extinct (X)
A species that no longer exists..

Extirpated (XT)
A species no longer existing in the wild in Canada, but occurring elsewhere..

Endangered (E)
A species facing imminent extirpation or extinction..

Threatened (T)
A species likely to become endangered if limiting factors are not reversed..

Special Concern (SC)Footnote1
A species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats..

Not at Risk (NAR)Footnote2
A species that has been evaluated and found to be not at risk..

Data Deficient (DD)Footnote3
A species for which there is insufficient scientific information to support status designation.

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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