1

This publication is part of a series that provides an overview of the presence of invasive plant species monitored on an 

extensive systematic network of plots measured by the Forest Inventory and Analysis (FIA) program of the U.S. Forest 

Service, Northern Research Station (NRS). Each research note features one of the invasive plants monitored on forested 

plots by NRS FIA in the 24 states of the midwestern and northeastern United States.

Background and Characteristics

Nonnative bush honeysuckles (Lonicera species) are native to 

Eurasia and were introduced in the 1700s (Czarapata 2005, Rich 

2000). These vigorous, woody shrubs are found throughout the 

United States and were promoted for ornamental use, wildlife 

habitat, and erosion control. Due to their widespread planting 

and vigorous spread, nonnative bush honeysuckles have become 

problematic in urban areas, abandoned fields, and forest land.

Several characteristics contribute to the proliferation of nonnative 

bush honeysuckle such as the ability to survive across a wide 

range of moisture and light regimes, leaf out early, and hold leaves 

later than most native forest species. In addition, nonnative bush 

honeysuckle do not require disturbance to establish and they 

reduce available moisture, light, and nutrients (Czarapata 2005). 

By reducing the available resources, the plant community can 

change, which in turn impacts the fauna through altered forage 

and habitat. An example is noted by Czarapata (2005) and Rich 

(2000) where several species of birds experience higher nest 

predation in nonnative bush honeysuckle compared to taller, 

native species.

Description

Growth: upright, woody, deciduous perennial shrub to nearly 

20 feet. Older shrubs have shaggy bark with stems that are often 

hollow. Leaves are opposite, simple, and entire.

Flowers: tubular, fragrant, red, pink, or white (Fig. 1); late spring.

Fruit: abundant yellow, orange, or red berries (Fig. 2), in pairs, 

beginning when plant is around 3 to 5 years old.

Reproduction: abundant fruit, frequently bird dispersed.

Habitat: thrives on sunny, upland sites but tolerates a wide variety 

of habitats including wetlands and forests. Common on forest 

edges, roadsides, abandoned fields, and homestead sites

Control: burning, cutting with herbicide application, and hand 

pulling (Czarapata 2005, Rich 2000).

United States Department of Agriculture

An Assessment of Nonnative Bush Honeysuckle in Northern U.S. Forests Research Note NRS-203

Forest Service

Northern Research Station

Figure 1.—Nonnative bush honeysuckle in flower.

Photo by Cassandra M. Kurtz, U.S. Forest Service.

Figure 2.—Morrow’s honeysuckle fruit. Photo by Leslie J. 

Mehrhoff, University of Connecticut, Bugwood.org.
2

In addition to the standard Phase 2 (P2) FIA plots, a subset of these plots are designated P2 Invasive where the 

standard Phase 2 variables (U.S. Forest Service 2014) are collected in addition to data on Invasive plants. The P2 

Invasive plots are measured from May 1 through September 30. For the 2009 through 2013 inventory period, field 

crews visited 6,815 forested P2 Invasive plots. This 5-year cycle (2009 through 2013), where 20 percent of the plots 

are measured each year, is collectively labeled the “2013 inventory” and was used to produce this report. Forty 

invasive plant species1 (IPS) (39 species and one undifferentiated genus [nonnative bush honeysuckles]2) were 

monitored. On each of these plots,3 various attributes were collected including the occurrence and coverage of IPS 

as well as the standard forest variables measured on P2 plots (e.g., tree diameter, height). Overall, 50.2 percent of 

forested plots had one or more of the monitored invasives present.

For this report, the species level data for nonnative bush honeysuckle species (Amur, Morrow’s, Tatarian, and 

showy fly honeysuckle) are compiled and discussed at the genus level. Species level data were combined with 

the genus level data since differentiation 

can be difficult and because field crew are 

not required to identify nonnative bush 

honeysuckles to the species level. In addition 

reporting at the genus level offers a broad 

overview of regional presence. Reporting at 

the genus level led to 1,204 nonnative bush 

honeysuckle observations, occurring on 

17.7 percent of P2 Invasive plots and makes 

nonnative bush honeysuckles the second 

most commonly recorded IPS of the 40 

monitored by the NRS. Only multiflora rose 

was more commonly observed, occurring on 

1,890 P2 Invasive plots (27.7 percent) in 2013. 

Nonnative bush honeysuckles are present 

in 23 of the 24 NRS states (Fig. 3), with no 

observances recorded in Rhode Island. Illinois 

has the greatest percentage of plots with 

nonnative bush honeysuckle (39.9 percent). 

This invasive shrub is also present on over 

one-third of the plots in Indiana, New York, 

and Iowa (37.4, 36.8, and 36.5 percent, 

respectively). Additional information about 

the species monitored and county level 

occurrence maps for the NRS region from 

2005 through 2010 can be found in Kurtz 2013.

Nonnative Bush Honeysuckle Presence on Phase 2 Invasive Plots

1 Autumn olive (Elaeagnus umbellata), black locust (Robinia pseudoacacia), Bohemian knotweed (Polygonum xbohemicum), bull 

thistle (Cirsium vulgare), Canada thistle (Cirsium arvense), Chinaberry (Melia azedarach), common barberry (Berberis vulgaris), 

common buckthorn (Rhamnus cathartica), common reed (Phragmites australis), creeping jenny (Lysimachia nummularia), dames 

rocket (Hesperis matronalis), English ivy (Hedera helix), European cranberrybush (Viburnum opulus), European privet (Ligustrum 

vulgare), European swallow-wort (Cynanchum rossicum), garlic mustard (Alliaria petiolata), giant knotweed (Polygonum 

sachalinense), glossy buckthorn (Frangula alnus), Japanese barberry (Berberis thunbergii), Japanese honeysuckle (Lonicera 

japonica), Japanese knotweed (Polygonum cuspidatum), Japanese meadowsweet (Spiraea japonica), leafy spurge (Euphorbia 

esula), Louise’s swallow-wort (Cynanchum louiseae), multiflora rose (Rosa multiflora), Nepalese browntop (Microstegium 

vimineum), nonnative bush honeysuckles (Lonicera spp.), Norway maple (Acer platanoides), Oriental bittersweet (Celastrus 

orbiculatus), princesstree (Paulownia tomentosa), punktree (Melaleuca quinquenervia), purple loosestrife (Lythrum salicaria), reed 

canarygrass (Phalaris arundinacea), Russian olive (Elaeagnus angustifolia), saltcedar (Tamarix ramosissima), Siberian elm (Ulmus 

pumila), silktree (Albizia julibrissin), spotted knapweed (Centaurea stoebe ssp. micranthos), Chinese tallow (Triadica sebifera), tree 

of heaven (Ailanthus altissima).

2 The 39 IPS and one undifferentiated genus (nonnative bush honeysuckles) are hereafter referred to as “invasive species”, 

“invasive plants”, “invasives”, or “IPS”.

3 Each FIA plot consists of four circular 1/24-acre subplots located at the corners and center of an equilateral triangle that is 208 

feet on a side.

Figure 3.—Inventory reporting area showing percent of Phase 2 

Invasive plots with nonnative bush honeysuckle, 2013.
3

Nonnative bush honeysuckle observances are shown in Figure 4 and illustrate the widespread 

occurrence of this genus. When looking at this figure, it is important to remember that this inventory 

only occurs in areas that meet FIA’s definition of forest land.4 Together Figures 3 and 4 reveal 

important information related to the presence and abundance of nonnative bush honeysuckles in the 

region. Over time, these maps will allow us to assess changes in abundance and spread.

Further Analysis

When able to identify the species of 

nonnative bush honeysuckle (Amur, 

Morrow’s, showy fly, or Tatarian 

honeysuckle), field crew can indicate which 

species they observe. Showy fly honeysuckle 

(Lonicera xbella), one of the nonnative bush 

honeysuckles found throughout our region, 

is a hybrid between Morrow’s and Tatarian 

honeysuckle. Analyzing the species level 

nonnative bush honeysuckle data shows 

that Morrow’s honeysuckle is the most 

commonly observed species (Fig. 5) (345 

plots; 5.1 percent). Amur honeysuckle is 

the next most frequently recorded species 

(261 plots; 3.8 percent), followed by Tatarian 

(51 plots; 0.7 percent) and showy fly 

honeysuckle (48 plots; 0.7 percent).

Despite being ecologically similar, these 

species differ in range. Amur honeysuckle 

is most problematic in the southern part 

of this region but is spreading northward 

(Czarapata 2005). It will be important 

to continue to monitor the spread and 

abundance of each of the species of 

nonnative bush honeysuckle over time as 

these species are having vast ecological and 

economic impacts across the landscape.

Nonnative Bush Honeysuckle Cover on Phase 2 Invasive Plots

Figure 5.—Morrow’s honeysuckle observances, 2013.

Figure 4.—Nonnative bush honeysuckle observances, 2013.

4 In general, area must be at least 10 percent stocked with trees of any size or formerly having such tree cover 

and not currently developed for nonforest use with a minimum classification area of 1 acre and 120 feet in width.
4

Nonnative bush honeysuckle, a shrub often used as an 

ornamental, was more common on plots near roads. There 

was a significant difference (t-test; p<0.05) in the distance to 

the nearest road for plots with and without nonnative bush 

honeysuckle (Fig. 6). These findings emphasize the importance 

of intact forest land.

Roads act as a conduit for seed dispersal and alter light and 

nutrient availability, as well as drainage. Vehicles traveling on 

roads can carry propagules of many exotics which become 

dispersed along them. Roads have been found to be important 

vectors for IPS (Kurtz and Hansen 2013, Lundgren et al. 2004, 

Predick and Turner 2008).

Characteristics of Plots with Nonnative Bush Honeysuckle

Figure 6.—Average distance to the nearest 

road for plots with or without nonnative 

bush honeysuckle, 2013.

Figure 9.—Percentage of the plot that is forested for 

plots with or without nonnative bush honeysuckle, 2013.

*Note: the error bars in figure 6 through 9 show a 68 percent confidence interval for the observed mean.

Further analysis of plots with and without nonnative bush 

honeysuckle shows that plots with nonnative bush honeysuckle 

tend to be less forested (t-test; p<0.05) (Fig. 9). Overall, plots 

with nonnative bush honeysuckle are 6 percent less forested 

than plots without nonnative bush honeysuckle. This indicates 

nonnative bush honeysuckle occurs more frequently along 

forest/nonforest edges than in the forest interior.

Monitoring IPS is important to determine status, trends, 

distribution, and population size, as well as to detect new 

populations. The trends found in this research note are important 

and need to be reported in the future to help elucidate factors 

related to the presence of these invasives as well as to find out 

the impacts these species are causing on biota and ecosystems. 

This research provides non-biased data to land managers and 

other concerned individuals to help with management decisions.

0

500

1,000

1,500

2,000

2,500

Absent Present

Road distance (ft)

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20

30

40

50

60

70

80

90

100

Percent forested

Absent Present

Figure 7.—Trees per acre ≥1 inch d.b.h. with or without nonnative 

bush honeysuckle, 2013.

Figure 8.—Trees per acre ≥5 inches d.b.h. with or without 

nonnative bush honeysuckle, 2013.

Tree cover also differs for plots with and without nonnative bush honeysuckle. The 2013 data suggest that there are fewer trees per acre 

on plots with nonnative bush honeysuckle (t-test; p<0.05) (Figs. 7 and 8). Since the study has only been running for a short period of time 

(complete implementation across the region in 2007), it is difficult to assess whether the invasive plants are influencing tree regeneration 

and growth or if the invasive plants are establishing where there is low tree cover and less competition. Continued monitoring is 

important because these plants can outcompete native species and without adequate understory regeneration to replace the aging 

overstory, the future of the forest remains in question. These preliminary results are important as they suggest there is a difference 

between plots with and without nonnative bush honeysuckle and future studies will help determine the effects these species are causing.

0

100

200

300

400

500

600

700

800

Number of trees per acre ≥ 1 inch d.b.h.

Absent Present

0

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60

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100

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140

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180

Number of trees per acre ≥ 5 inches d.b.h.

Absent Present
5

Citation for this Publication

Kurtz, C.M.; Hansen M.H. 2015. An assessment of nonnative bush honeysuckle in northern U.S. forests. Res. Note NRS-203. 

Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 5 p

FIA Program Information

Bechtold, W.A.; Patterson, P.L., eds. 2005. The enhanced Forest Inventory and Analysis Program: national sampling design 

and estimation procedures. Gen. Tech. Rep. SRS-80. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern 

Research Station. 85 p.

Smith, W.B. 2002. Forest inventory and analysis: a national inventory and monitoring program. Environmental Pollution. 

116: 233-242.

References

Czarapata, E.J. 2005. Invasive plants of the upper Midwest: an illustrated guide to their identification and control. Madison, 

WI: The University of Wisconsin Press. 215 p.

Kurtz, C.M. 2013. An assessment of invasive plant species monitored by the Northern Research Station Forest Inventory 

and Analysis Program, 2005 through 2010. Gen. Tech. Rep. NRS-109. Newtown Square, PA: U.S. Department of Agriculture, 

Forest Service, Northern Research Station. 70 p.

Kurtz, C.M.; Hansen, M.H. 2013. An assessment of multiflora rose in northern U.S. forests. Res. Note NRS-182. Newtown 

Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 5 p.

Lundgren, M.R.; Small, C.J.; Dreyer, G.D. 2004. Influence of land use and site characteristics on invasive plant abundance in 

the Quinebaug Highlands of southern New England. Northeastern Naturalist. 11(3): 313-332.

Predick, K.I.; Turner, M.G. 2008. Landscape configuration and flood frequency influence invasive shrubs in floodplain 

forests of the Wisconsin River (USA). Journal of Ecology. 96: 91-102.

Rich, R. 2000. Beautiful Species to Hate: Non-native bush honeysuckles: Invasive Lonicera species in the midwest.

Restoration and Reclamation Review. Student On-Line Journal. 6(5): 1-9.

U.S. Department of Agriculture, Natural Resource Conservation Service. (USDA, NRCS). 2014. The PLANTS Database.

Greensboro, NC: National Plant Data Team. Available at http://plants.usda.gov (accessed 21 Apr 2014).

U.S. Forest Service. 2014. Forest inventory and analysis national core field guide, Vol. 1: field data collection procedures for 

phase 2 plots, ver. 6.1. Available at www.fia.fs.fed.us/library/field-guides-methods-proc/ (verified 20 Jul 2015).

Additional Invasive Plant Information

Alien Plant Invaders of Natural Areas (PCA, National Park Service): http://www.nps.gov/plants/alien/factmain.htm

Invasive and Exotic Plants: http://www.invasive.org/species/weeds.cfm

Invasive Plant Atlas of New England: http://www.eddmaps.org/ipane/

Invasive Plant Atlas of the United States: http://www.invasiveplantatlas.org/index.html

Midwest Invasive Plant Network: http://mipn.org/

Contact

Analyst: Cassandra Kurtz, (651) 649-5149; cmkurtz@fs.fed.us

Page 1 and 5 header by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

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