Exotic Plant Species in Old-Growth Forest in Indiana

Abstract

Old-growth forest in Indiana consists of a few remnant stands in a fragmented agricultural landscape. Old-growth stands can differ substantially from more recently disturbed stands in species composition and may be less susceptible to invasion by exotic plant species. Herbaceous species were sampled in quadrats placed in a repeating pattern along two perpendicular transects in six Old-growth stands in Indiana in spring and summer of 2005. Transects extended from forest edges to the center of each stand. Woody exotic species were sampled in 10-m-wide belts centered on each transect during the summer sampling run. Herbaceous exotic species were a minor component of the understory community in all stands and accounted for less than 1% of total herbaceous cover in all six stands. Exotic woody species generally followed a similar pattern. Four sites contained no more than two woody exotic species, and these were encountered at relatively low frequencies and densities. However, European privet and multiflora rose were present in 27 and 48% of quadrats in one stand, respectively. Thus, although both herbaceous and woody exotic species were relatively rare, heavy infestations of woody exotic species are possible. This suggests that, for some Old-growth sites, exotic species can overcome both local and landscape factors that limit their abundance.

Potential Range Expansion of Japanese Honeysuckle (Lonicera japonica Thunb.) in Southern U.S. Forestlands

“…However, planting native species and subsequent management for those species reduces the opportunity for L. japonica spread. Also, the resulting single-aged stand has lower potential for future small gap dynamics which L. japonica might exploit, given that most of the trees will survive to harvestable age and L. japonica invasion is severely restricted in closed canopy conditions [72].…”

A Panax-centric view of invasive species

“…R. multiflora has been found to be one of the most frequent invasive plants in an old growth forest in Indiana (Weber and Gibson 2007), and within forest fragments (Brothers and Spingam 1992). Another study found both invasive species to be dominant across their sites (Lundgren et al 2004).…”

“…Traditionally, presence-absence surveys utilize randomly placed transects or quadrats to sample species occurrence (McIntyre et al 1995;Weber and Gibson 2007). However, the aim of this paper was to examine the level of exposure of only ginseng plants.…”

“…On one hand, many invasives occupy disturbed habitats (Hobbs and Huenneke 1992;Marvier et al 2004;Stolgren et al 1999), which are uncharacteristic for forest herbs such as ginseng (Anderson et al 1993). However, the diversity of habitats ginseng occupies (McGraw et al 2003), the fact some invasive plants do penetrate undisturbed forests (Ehrenfeld 1997;Knapp and Canham 2000;Nuzzo 1999;Weber and Gibson 2007), and the long lifetimes of ginseng plants, suggest that the effects of invasives could be important. Furthermore, given ginseng's widespread occurrence in eastern deciduous forests (Charron and Gagnon 1991), ginseng may be exposed to invasives at rates similar to other understory herbs.…”

Competitive and allelopathic effects of garlic mustard (Alliaria petiolata) on American ginseng (Panax quinquefolius)

“…Cavara & Grande) is a Eurasian biennial that has spread rapidly in forests in southern Canada and 36 states in the U.S. (Cavers et al 1979;Nuzzo 2000;Welk et al 2002;USDA 2008). This species forms dense, monotypic stands within forest edges, floodplains, undisturbed understories, and even old-growth forests (Nuzzo 1993;Nuzzo 1999;Stinson et al 2006;Weber and Gibson 2007), reducing growth, abundance, and diversity of native species (McCarthy 1997;Stinson et al 2006;Stinson et al 2007).…”