FIELD WORK: The Great Swamp’s
Callery pear trees were left
behind by a commercial nursery
that had closed. To eradicate the
invaders, the strike team cuts
down what it can and sprays the
remnants with an herbicide that
blocks future growth. Left to
proliferate, the Callery pears will
crowd out native species.
EMERALD ASH BORER
SOURCE: NJ Invasive Species Strike Team.
Here are the 10 worst invasive
threats to NewJersey’s
The Top 10
cies outside of some honeysuckle or mul-
tiflora rose,” says Van Clef. Then came the
building boom of the 1970s and “the rate of
change of new species adding to the mix is
like a rapid-fire Gatling gun. It’s stressing
In 2004, Governor Jim McGreevey
recognized the threat and established the
New Jersey Invasive Species Council. Van
Clef drew up a strategic action plan for the
council in 2007.
The plan, which was adopted in the
waning days of the Corzine administration,
recommended creation of a strike team to
collect data from across the state and implement strategies to limit the spread of invasives, primarily by early detection.
In 2010, Governor Chris Christie swept
away some 60 councils, commissions and
task forces that he said were unnecessary.
Among those to disappear were little-known groups like the Billboard Policy
Procedure and Review Task Force and the
Governor’s Study Group on the Bicentennial of the Polish Constitution.
The Invasive Species Council also got
But Van Clef’s work did not go to waste.
With the Friends of Hopewell Valley Open
Space, where he is stewardship director,
as a base, and with help from other local
organizations—most notably the Raritan
Headwaters Association—he already had
created the strike team. That effort brings
together volunteers to collect data, monitor hot spots and provide arms and legs for
In 2008, the strike team helped the
New Jersey Conservation Foundation clean up a 50-acre parcel of land
in Hunterdon County that contained
about 10 ponds on a former commercial
Tim Morris, the foundation’s director
of stewardship, recalls that about a year af-
ter the foundation purchased the hatchery
land, a fisherman caught a bighead carp in
one of the ponds whose waters empty into
the Delaware River. That was bad news.
The bighead—which in rare instances can
grow to 100 pounds—is known to outcom-
baggage. The state’s diverse topography is
one of the factors that make it a compliant
host. It has been estimated that as many
plant species grow here as in New York
and Pennsylvania, states that are three to
four times larger.
Not all introduced plants are invasive,
but all the trouble makers share some
nasty traits. They can survive in the wild,
they produce mountains of seeds and their
offspring take root easily. Most critically,
they can crowd out natural species and reduce biodiversity.
While non-natives have been here for
a long time, suburbanization and the proliferation of garden nurseries and big-box
stores have drastically accelerated the
spread of new species.
“In the 1950s, you could have gone anywhere and barely seen any invasive spe-