New Jersey rush (Juncus caesariensis) COSEWIC assessment and status report: chapter 8
Limiting Factors and Threats
Juncus caesariensis is considered to be most sensitive to circumstances affecting the hydrologic regime of its habitat (Schuyler, 1990; Kral, 1983; Ware and Wieboldt, 1981) such as site drainage or prolonged flooding. Potential anthropogenic threats to Canadian populations that might affect drainage patterns or promote excessive flooding are logging, cottage, home or resort development and road building. Many of the populations in Nova Scotia occur near the coast. Coastal real estate in Nova Scotia is currently in very high demand for home and cottage development.
Clear cutting practices that do not allow for the establishment of buffers between wetlands and logged areas may also have a negative impact on New Jersey Rush by affecting local drainage patterns.
Recent road construction across one wetland was observed in 2002 (Site 3). Continued monitoring at this site is recommended in order to determine if this will have a detrimental effect on the populations of New Jersey Rush located there. The local office of the Department of Environment and Labour should be alerted to the presence of New Jersey Rush in their jurisdiction so that the future granting of permits for wetland alteration will take this into consideration.
Natural succession could lead to the temporary and possibly the permanent disappearance of New Jersey Rush populations. There are several cases in the United States where canopy removal either through logging practices or clearing for power line right-of-ways led to the reappearance of New Jersey Rush (Schuyler, 1990; Strong and Sheridan, 1991). It is believed that the plants are able to persist in vegetative form reverting to sexual reproduction upon opening of the canopy. It is unknown how long they are able to persist after canopy closure.
Newell and Newell (1992) reported that the existing level of all-terrain vehicle activity in the Nova Scotia wetlands where New Jersey Rush occurs did not appear to be negatively impacting the populations of this species. However, it was suggested that an increase in the activity level may lead to damage to or destruction of some plants or populations. Observations in 2002 determined that there has been some increase in the level of ATV activity at a number of the New Jersey Rush sites. However, this does not appear to be negatively impacting the plants thus far. In fact, the plants in these disturbed sites are often more vigorous (i.e., more culms per plant) than plants in undisturbed sites. It may be a matter of frequency and timing where ATVs are concerned. A significant increase in activity and/or, a change in the time of the year when ATVs are used may be more likely to negatively impact the New Jersey Rush populations.
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