Non-Native Plant Inventory: Kenai Trails

Transcription

1 Non-Native Plant Inventory: Kenai Trails M.E. Shephard photo 1 R.L. DeVelice, Vegetation Ecologist USDA Forest Service, Chugach National Forest 3301 C Street, Suite 300 Anchorage, Alaska Close-up of ground vegetation at a campsite along the Ptarmigan Creek Trail at Ptarmigan Lake (site 03PTA223). Dominate plants include Poa annua (annual bluegrass; 50% cover) and Plantago major (common plantain; 40% cover). That plant featured on E. Bella s hand is Matricaria discoidea (pineappleweed; 1% cover). R10-TP-124

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3 Summary In 2003, a study was initiated to document non-native plant species occurrences on about 320 km (200 miles) of trail on the Kenai Peninsula portion of the Chugach National Forest. At 1-kilometer (0.62 mile) increments along each trail, sample plots were established listing the occurrence and abundance of nonnative plant species present. In addition, established campsites and cabin sites and larger infestation areas between the 1-kilometer systematic plots were sampled. By the close of field season, 220 plots (50-m 2 each) were established along 175 km (110 miles) of trail. The trail plots were 2.5 x 20 m in size, centered on the trail, with the long axis parallel to the trail. The campsite and cabin plots were 7.07 x 7.07 m in size and were centered on locations of highest concentration of non-native species. If a non-native species at a site extended beyond the boundaries of a plot into adjacent native vegetation, that expansion was noted. In total, 24 non-native plant species were observed. In addition the occurrence of 5 species of ambiguous origin was documented. Non-native plants are common along most of the trails surveyed (found on 75 percent of trail plots) but are presently rare within natural vegetation communities of the area (found on 2.5 percent of natural community plots). Of the 220 trail sites, low cover of nonnative plants plus plants of ambiguous origin occurred most frequently in forests (52% of sites) while high cover was most frequent on shrubland and herbaceous sites (25 and 21% of sites, respectively). 3

4 Non-Native Plant Inventory: Kenai Trails The introduction and spread of non-native plants species is a growing concern in Alaska 2. Baseline abundance and distribution information on non-native plants is needed to assess the magnitude of the problem, determine potential locations for control treatments, and track changes in plant populations. In 1997 and 1998, preliminary surveys of non-native plant species occurred on the Copper River Delta and Kenai Peninsula portions of the Chugach National Forest (Duffy 2003). These surveys focused on sites where infestations were expected to occur such as road edges, visitor facilities, and trailheads. When the data reported in Duffy (2003) are combined with data from sites chosen to represent natural communities (e.g., DeVelice et al. 1999) it is found that most areas of non-native plant occurrence on the Chugach are presently in areas of intensive humancaused disturbance. There is an extensive network of trails leading into the backcountry on the Kenai Peninsula portion of the Forest. Since these trails constitute areas of intensive human-caused disturbance extending into remote areas they provide potential avenues for non-native plant expansion. To provide an initial inventory of the extent of this potential problem, a study was initiated in 2003 to document nonnative plant species occurrences on about 320 km (200 miles) of trail in the Kenai Mountains. Methods A GIS was used to distribute sample plots at 1-kilometer (0.62 mile) increments along all hiking trails 2 km length in the Kenai Mountains. In addition, established campsites and cabin sites and larger infestation areas between the 1-kilometer systematic plots were sampled. By the close of the 2003 field season, 220 plots (50-m 2 each) were established along 175 km (110 miles) of trail (Figure 1). The trail plots were 2.5 x 20 m in size, centered on the trail, with the long axis parallel to the trail. The campsite and cabin plots were 7.07 x 7.07 m in size and were centered on locations of highest concentration of non-native species. In each plot, the occurrence and abundance of non-native plant species present was recorded (Figure 2). The plant community type(s) in which the plot occurred was also recorded using the DeVelice et al. (1999) classification. If a non-native species at a site extended beyond the boundaries of a plot into adjacent native vegetation, that expansion was noted. 2 For further information on current programs related to non-native plant inventory and control in Alaska check the websites of the Alaska Committee for Noxious and Invasive Plants Management ( and the Alaska Exotic Plants Information Clearinghouse ( 4

5 The composition/cover data were entered into Paradox 9 database files and the UTM coordinates of the centroid of each plot were entered into an ArcGIS shapefile 3. In this report, the data from 2003 were combined with trailhead non-native plant data collected in 1998 (Duffy 2003) and data from sample plots in areas remote from trails and roads (DeVelice et al. 1999). Results and Discussion A total of 24 non-native plant species were observed (Table 1). In addition, the occurrence of 5 species of ambiguous origin was documented. Of the species listed in Table 1, 20 were observed in the 2003 surveys and the remaining 9 were documented at trailheads in As an index of relative abundance of each of the 20 species observed in 2003, an importance value 4 was calculated (Table 2). These 20 species include the 10 most common non-native plant species (based on importance values) documented on the Chugach National Forest by Duffy (2003). Maps showing the distribution and abundance of these top 10 species across the 220 sample plots from 2003 and 808 plots used in the development of the DeVelice et al. (1999) classification are presented in Figure 3. The 808 plots from the DeVelice et al. (1999) work were all on sites representing natural communities. Therefore, these plots provide a reference of non-native plant species occurrence and abundance on sites with minimum human-caused disturbance. Among these plots, 394 vascular plant species were documented. Of these, six 5 are non-native species and four 6 are species of ambiguous origin. The combined cover of these 10 species across the 808 plots is 68 percent, which is 0.06 percent of the total vascular plant cover across all plots (i.e., 68 non-native cover/114,747 total vascular plant cover x 100 = 0.06 percent). Additionally, of the 220 sites surveyed along trails, non-native plants or species of ambiguous origin were found on 165 (75 percent of the plots). In contrast, in natural vegetation communities, of 808 sites sampled in the development of the DeVelice et al. (1999) classification, non-native plants or species of ambiguous 3 These data are included in the WinZip 8.0 file weeds_2003.zip as follows: weeds_2003_xy.shp is the GIS shapefile; weed_veg.db is the species cover data; weed_spp.db lists the species codes and names; and weed_mem.db is the list of plot numbers and plant communities. 4 The method for calculating importance value follows Duffy (2003) and is the square root of the product of average cover and constancy. Average cover was calculated by dividing the sum of all cover values for a species by the number of occurrences. Constancy was calculated as the number of occurrences of each species divided by the total number of sites (i.e., 220 sites) multiplied by Brassica rapa L., Lupinus polyphyllus Lindl., Phleum pratense L., Poa nemoralis L., P. palustris L., and P. pratensis L. 6 Carex deweyana Schwein., Festuca rubra L., Myriophyllum spicatum L., and Veronica serpyllifolia L. 5

6 origin were found on 20 (2.5 percent of the plots). Based on these results, it may be stated that non-native plants are common along most of the trails in the Kenai Mountains but are presently rare within natural vegetation communities of the area. Of the 220 trail sites, low cover of non-native plants occurred most frequently in forests while high cover of non-native plants occurred most frequently on shrubland and herbaceous sites (Table 3). Non-native species were rarely found in vegetation of the alpine zone (as defined by dominance of such species as Carex microchaeta, Cassiope stellariana, Dryas octopetala, Empetrum nigrum, Hierochloë alpina, Luetkea pectinata, Phyllodoce aleutica, Salix arctica, S. rotundifolia, and Vaccinium uliginosum). Of the 220 plots, 16 were in the alpine zone. Non-native plants were only present on one of the 16 plots (10 percent cover of Poa annua in a plot on the Crow Pass Trail). Of the 220 sites surveyed along trails, non-native species occurrences extended beyond the boundaries of the 50-m 2 plot at 8 of the sites (Table 4). The most common species found to extend beyond the sample plots were Taraxacum officinale and Poa pratensis. When combined with data from previous surveys of non-native plant species along roads (Duffy 2003) and data from over 2300 sample plots in areas remote from trails and roads (DeVelice et al. 1999), the trail data provide baseline information on non-native plant species distribution and ecology on the Forest. The data are also useful in identifying potential priority areas for non-native plant control. Management Implications 7 Where trails traverse shrubland or herbaceous areas, the trail and adjoining plant communities are more prone to invasion of non-native species. Some locations along the Hope Point Trail feature abundant cover of Taraxacum in natural and human-caused disturbance areas adjacent to the trail (Figure 4). Such sites are potential priority areas for control measures since the non-native species appear to be spreading. Since non-native plant occurrence and abundance tends to increase with humancaused disturbance, non-native plant populations may expand with the intensity of trail maintenance. Trail maintenance of the intensity shown in Figure 5 will likely promote non-native plant occurrence, particularly in shrubland and herbaceous communities. Within conifer forest, trails are fairly resilient to 7 M.E. Shephard (USDA Forest Service, State and Private Forestry, Anchorage, Alaska) coauthored the Management Implications section). 6

7 maintenance levels since, in general, the acidic soils and shading prevent widespread establishment of many of the common non-native species. A narrower tread and the maintenance of native grasses and forbs in close proximity to the tread will help prevent non-native plant establishment. When drainage work along trails is needed, a light touch is suggested to maintain the root structure of the perennial native grasses and forbs. When brushing the trail edge, leaving the vegetation at least 25 cm (10 inches) tall would usually allow many more native species to persist, prosper, and perhaps out-compete nonnative species. In addition, it is desirable to maintain dead organic matter on the surface, rather than remove it, since such mulch can reduce the establishment and growth of non-native plants. The cleaning of tools and equipment between work sites along the trail will help prevent transport of non-native seed and vegetative reproductive structures further along the trail. 7

8 Literature Cited DeVelice, R.L., C.J. Hubbard, K. Boggs, S. Boudreau, M. Potkin, T. Boucher, and C. Wertheim Plant community types of the Chugach National Forest: southcentral Alaska. USDA Forest Service, Chugach National Forest, Alaska Region Technical Publication R10-TP-76. Anchorage, Alaska. 375 pp. Duffy, M Non-native plants of Chugach National Forest: a preliminary inventory. USDA Forest Service, Chugach National Forest, Alaska Region Technical Publication R10-TP-111. Anchorage, Alaska. Xxx pp. Hultén, E Flora of Alaska and neighboring territories. A manual of the vascular plants. Stanford University Press, Stanford, California pp. Welsh, S.L Anderson s flora of Alaska and adjacent parts of Canada. Brigham Young University Press, Provo, Utah. 724 pp. Acknowledgements I appreciate the field assistance provided by Chugach National Forest Ecologists Betty Charnon and Elizabeth Bella of the Glacier and Seward ranger districts, respectively, and Michael Shephard, Ecologist with USDA Forest Service, State and Private Forestry in Anchorage, Alaska. Thanks are also extended to Beth Schulz of the USDA Forest Service, Pacific Northwest Research Station for her review of a draft of this report. 8

9 Table 1. Non-native plants observed on trails in the Kenai Mountains. NRCS Code Scientific Name Common Name ALGE2 Alopecurus geniculatus L. water foxtail x ALPR3 Alopecurus pratensis L. meadow foxtail x x BRIN2 Bromus inermis Leyss. smooth brome x CABU2 Capsella bursa-pastoris (L.) Medik. shephard's purse x x CEFO2 Cerastium fontanum Baumg. larger mouse-ear chickweed x x CRTE3 Crepis tectorum L. annual hawksbeard x LEVU Leucanthemum vulgare Lam. oxeye daisy x x LOPE Lolium perenne L. perennial ryegrass x MADI6 Matricaria discoidea DC pineappleweed x x MESA Medicago sativa L. alfalfa x MEOF Melilotus officinalis (L.) Lam. yellow sweet clover x PHPR3 Phleum pratense L. Timothy x x PLMA2 Plantago major L. common plantain x x POAN Poa annua L. annual bluegrass x x POPR Poa pratensis L. Kentucky bluegrass x x POTR2 Poa trivalis L. rough bluegrass x x POAV Polygonum aviculare L. prostrate knotweed x x RARE3 Ranunculus repens L. creeping buttercup x x RUAC3 Rumex acetosella L. common sheep sorel x RUCR Rumex crispus L. curled dock x STME2 Stellaria media (L.) Vill. common chickweed x x TAOF Taraxacum officinale G. H. Weber ex Wiggers common dandelion x x TRHY Trifolium hybridum L. alsike clover x x TRRE3 Trifolium repens L. white clover x x The following species are of ambiguous origin and were noted during surveys: ACHIL Achillea sp. L. yarrow x x FERU2 Festuca rubra L. red fescue x x HOJU Hordeum jubatum L. foxtail barley x PONO3 Potentilla norvegica L. Norwegian cinquefoil x x VESE Veronica serpyllifolia L. thymeleaf speedwell x x 8 Species found on trails in 2003 surveys. 9 Species found at trailheads in 1998 surveys (Duffy 2003). Only trailheads of trails surveyed in 2003 are included. 9

10 Table 2. Importance values of the 20 non-native plant species and species of ambiguous origin observed on trails in the Kenai Mountains in Locations of occurrences of the 10 shaded species are presented in Figure 3. The 10 shaded species are those with the highest importance values documented on the Chugach National Forest by Duffy (2003). Average Importance Importance Scientific Name Cover Constancy Value Value Poa annua Poa pratensis Taraxacum officinale Plantago major Achillea sp Festuca rubra Trifolium repens Veronica serpyllifolia Phleum pratense Poa trivalis Matricaria discoidea Trifolium hybridum Polygonum aviculare Ranunculus repens Stellaria media Alopecurus pratensis Cerastium fontanum Potentilla norvegica Capsella bursa-pastoris Leucanthemum vulgare Calculated based on the 220 plots sampled on trails in As reported in Duffy (2003) based on 119 sites sampled across the Chugach National Forest in 1997 and

11 Table 3. Frequency of occurrence of low and high cover of non-native plants plus plants of ambiguous origin within the forest, shrubland, and herbaceous communities sampled in Community n Frequency of Low Cover ( 3% total cover) Frequency of High Cover (>40% total cover) Forest % 11% Shrubland 68 37% 25% Herbaceous 29 31% 21% 11

12 Table 4. Sites where non-native species occurrences were found to extend beyond the boundaries of the 50-m 2 sample plots. Plot Number Trail Name Notes 03CRE163 Crescent Creek Trail Taraxacum officinale is expanding both upslope and downslope of trail in disturbed areas. 03HOPE67 Hope Point Trail Taraxacum officinale is abundant off the trail in this area of braided trail on a steep, erosive slope. 03HOPE70 Hope Point Trail Taraxacum officinale is abundant off the trail in this area of braided trail on a steep, erosive slope. 03JPT106 Johnson Pass Trail: campsite Poa pratensis is common in meadows adjacent to the plot. 03JPT108 Johnson Pass Trail Poa pratensis is common under Alnus adjacent to the plot. 03RESP03 Resurrection Pass Trail: East Creek Cabin Poa pratensis and Taraxacum officinale are common under Salix adjacent to the plot. 03RESP12 Resurrection Pass Trail Poa pratensis is common in adjacent Epilobium community. 03RESP19 Resurrection Pass Trail Some Poa pratensis is present under Salix adjacent to the plot. 12

13 Figure 1. Location of the 220 plots (closed dots) sampled along trails in 2003 and 808 plots 12 (open circles) representing natural communities in the Kenai Mountains. 12 Used in the development of the DeVelice et al. (1999) classification. 13

14 Figure 2. Survey form used to document non-native plants observations on trails in the Kenai Mountains. 14

15 Poa annua (annual bluegrass) On 134 plots sampled in Annual, the remains of old stems never present; tufted or stoloniferous, dm tall; anthers less than 1 mm long; lemmas not webbed at base. Poa pratensis (Kentucky bluegrass) On 82 plots sampled in 2003 and 1 DeVelice et al. (1999) plot. Perennial; rhizomatous; dm tall; anthers 1-2 mm long; lemmas webbed at base. Figure 3. The distribution and abundance of the 10 most common non-native plant species reported on the Chugach National Forest by Duffy (2003) across the 220 sample plots from 2003 and 808 plots used in the development of the DeVelice et al. (1999) classification. The four sizes of dots on the maps represent the following four cover classes: percent (smallest dots); >3-20 percent; >20-40 percent; and >40 percent (largest dots). Line drawings of the species are from the NRCS PLANTS website ( Species descriptions are paraphrased from Hultén (1968) and Welch (1974). 15

16 Taraxacum officinale (common dandelion) On 61 plots sampled in dm tall; leaves 5-40 cm long, 1-10 cm broad, pinnately lobed to pinnatifid, lobes mostly toothed; rays yellow; achenes 3-4 mm long; pappus white. Plantago major (common plantain) On 53 plots sampled in Perennial; 1-5 dm tall; leaf blade ovate to broadly elliptic, mostly 1-3 times longer than broad; spike dense; corolla yellowishwhite. Figure 3. Continued. 16

17 Achillea millifolium (common yarrow) On 44 plots sampled in dm tall; leaves 2-20 cm long, pinnately dissected, the divisions again dissected; heads in hemispheric or flattopped, corymbose cymes; rays white to pink. Phleum pratense (Timothy) On 21 plots sampled in 2003 and 4 DeVelice et al. (1999) plots. Tufted, culms usually bulbous based, 3-15 dm tall; sheaths not inflated; panicles commonly more than 4.5 cm long and less than 1 cm broad. Figure 3. Continued. 17

18 Trifolium repens (white clover) On 17 plots sampled in Perennial; stoloniferous, stems rooting at nodes, creeping; leaves long petioled, trifoliate; flowers usually white. Trifolium hybridum (alsike clover) On 5 plots sampled in Perennial; not stoloniferous, stems not rooting at nodes, erect; leaves with progressively shorter petioles upwards, trifoliate; flowers pink to reddish or white. Figure 3. Continued. 18

19 Matricaria discoidea (pineappleweed) On 13 plots sampled in Annual; dm tall, branching above, aromatic; leaves 1-3 pinnatifid with filiform segments; flowering heads usually several; ray flowers lacking. Cerastium fontanum (larger mouse-eared chickweed) On 5 plots sampled in Biennial or short-lived perennial; stems dm, decumbent to erect; leaves cm long, cm broad, coarsely pubescent; petals white, about as long as sepals. Figure 3. Continued. 19

20 Figure 4. Close up of ground cover with abundant Taraxacum offinale (common dandelion) adjacent to the Hope Point Trail in an area of braided trail on a steep, erosive slope (site 03HOPE67; R.L. DeVelice photo). 20

21 Figure 5. Recent maintenance work on the Ptarmigan Creek Trail (M.E. Shephard photo). 21

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24 United States Department of Agriculture Forest Service