Exotic plants

[Michael Gochfeld]

As a followup on recent postings concerning exotic vegetation (pros and 
cons), I want to raise some alarm about several species that are 
adversely affecting butterfly habitats. 

Garlic Mustard (as previously mentioned) has had a banner year and in 
some places has developed a monoculture understory which threatens 
native woodland and edge herbs.  Crucifers (Dentaria, Arabis, Cardamine) 
seem to be easily overgrown.  Wildflower officionados may have other 
species of concern as well. 

Multiflora Rose is now the main early successional bush and is 
eliminating stands of milkweed and dogbane.  I have yet to see any 
butterfly use this species. 

Japanese Polygonum (an 8' high bush) is rapidly invading woodland edge 
in central NJ and seems able to tolerate sun. It forms monoculture 
thickets that simply overgrow everything else.  We're watching with 
interest what happens when the Polygonum and Multiflora converge. Which 
will win out?

Oriental Bittersweet:  Monoculture thickets of this densely growing 
vine, are obliterating many edge habitats.  This is a big problem in 
northern Westchester County (New York) where I grew up, but is not yet 
rampand in central NJ.  Like Kudzu it simply grows over 
things---although it is not quite as rapid.  

Since these plants usurp early suscessional habitats that are otherwise 
spared, they synergize with "development" in reducing available habitat 
and nectar and host sources.  We noted with interest that at least one 
park system, Morris County Parks, has a volunteer task group which goes 
out to dig up exotics and restore native vegetation.