EXOTIC PLANT MANAGEMENT

FY2000 Progress Report Exotic Plant Management Prepared by Andrea Williams, Natalie Reed, Jim Popenoe and Diona Roja Division of Resource Management and Science Redwood National and State Parks Orick, California November 2000 FY2000 HIGHLIGHTS    RNSP completed a project reducing European beachgrass at Freshwater to a level that can be controlled with only routine maintenance. Previously controlled populations of Scotch broom, yellow bush lupine, sea-fig, white sweetclover, and English ivy were held to maintenance levels. New, large populations of English ivy were mapped in the Hiouchi / Jedediah Smith Redwoods State Park area. A plan was developed, and funding approved to attack the newly mapped ivy. Additional project plans to control Pampas grass, European beachgrass, English ivy and other species were developed for approval and implementation in FY01. RNSP staff participated actively on the local interagency Weed Management Area teams involved in mapping, managing, and educating the public about invasive plants in Northern California. A poster was prepared describing major park invasive plant control projects for "War On Weeds" week.   DETAILS 1. North District -- Andrea Williams 2. South District -- Natalie Reed 3. Elk Meadow -- Jim Popenoe 4. Person-Hour and Cost Tabulations -- Andrea Williams, Natalie Reed and Diona Roja APPENDICES A. NRPP Funding Proposal to Control English Ivy and other Shade Tolerance Species in the Hiouchi / Jedediah Smith Area B. Project Clearance for Control of English Ivy and other Shade Tolerance Species in Jedediah Smith Redwoods State Park C. Project Clearance to Control Pampas Grass at Redwood Creek Estuary D. Project Clearance to Control European Beachgrass from Redwood Creek to Mussel Point 1 NORTH DISTRICT Andrea Williams, Biological Science Technician October 16, 2000 HIGH-PRIORITY SPECIES English ivy (Hedera helix) We continued the ivy removal project begun last year around the Hiouchi Information Center. Six truckloads of ivy, with some periwinkle (Vinca major) and Himalaya blackberry (Rubus discolor), were removed. Resprout and seedling removal to the east of the information center parking lot was curtailed due to the discovery of the rare heart-leaf twayblade (Listera cordata) in areas previously cleared of ivy. Ivy removal was begun across from the visitor center, severing tree-climbing vines and clearing some of the ground growth. Ivy has been removed from the bulk of the campsites, but infestations remain in the housing areas of Hiouchi Flat. RNSP was awarded a grant from NRPP in support of shade-tolerant exotics removal (primarily ivy, but also cotoneaster, holly, and vinca) in Jedediah Smith Redwoods State Park. An ivy-removal project clearance (CEQA# 00-635A-014, approved October 4, 2000) was submitted to perform this work, which is estimated to be a three-year project. After that time, removal should not require effort beyond a maintenance level. Please reference the Spring/Summer 2000 Rare Plant Surveys report for Jedediah Smith Redwoods State Park and the above-mentioned CEQA for additional information. Scotch broom (Cytisus scoparius) Removal of a large population of Scotch broom was begun in Hiouchi. The areas cleared include along the service road across from the Hiouchi Information Center, and the burn meadow adjacent to the road. Many plants remain in the Hiouchi Flat area. Some smaller plants were pulled from the riverbank near the campground, but it was too late in the season and the ground was too hard for an effective attack on this population. Maintenance continues to pull seedlings from the field at Aubell. A pasture adjacent to the field had a large population, which the owners began to control late this summer. Tansy ragwort (Senecio jacobaea) Small populations of tansy ragwort occur in the burn meadow adjacent to the service road in Hiouchi, roadside on Highway 199 and Howland Hill Road, at the Mill Creek Horse Trail, and a larger population in the field at Aubell. Maintenance pulls most plants from these places; I pulled some from the field at Aubell. A pasture adjacent to the field had a large population, which the owners began to control late this summer. The Cinnabar moth was found near the Mill Creek Horse Trail, and larvae were on several plants pulled from Aubell. More consistent work and follow-up visits are needed to keep tansy ragwort from expanding in open areas. French broom (Genista monspessulana) A small population is intermixed with the Scotch broom along the service road and river bar. These will be eradicated concurrently with Scotch broom. Klamathweed (Hypericum perforatum) Small populations exist roadside along Highway 199, and in and around the burn meadow, service road, and gravel bar. Some control was done incidental to Scotch broom removal, but additional work will be needed. 2 Himalaya blackberry (Rubus discolor) No new control work was done on the populations of exotic blackberry on the Hampson Property (Parkway at Highway 199), Camp Lincoln, Aubell, or the campground area. In most of these areas, blackberry was mowed or pruned by maintenance staff. However, the plants will resprout unless root systems are removed. Some bushes were removed in the Hiouchi area. Spotted knapweed (Centaurea maculosa) Eradication of a small population on the gravel bar has been ongoing for several years. This year, late July surveys yielded no plants; four plants were found and pulled in late August. Last year less than a dozen plants were located and removed. Dave at Del Norte County Agriculture Department also surveys and removes plants in the area. OTHER SPECIES Cotoneaster (Cotoneaster franchetii) Large populations exist along Kings Valley Road (especially near Camp Lincoln) and in the Hiouchi area. Small shrubs were pulled from the campground area when encountered; some remain near the entrance and should be pulled this winter. Major removal was begun across from the Hiouchi Information Center; crews uprooted over 50 large shrubs. Most plants were lopped back to a main stem and pulled with a weed wrench while the root crown was dug out with a pulaski. Follow-up removal and resprout pulling will be necessary. The grant and CEQA, as noted in the English ivy section, covers cotoneaster removal in Jedediah Smith Redwoods State Park. Please reference that paragraph, and/or those documents, for additional information. English holly (Ilex aquifolium) While scattered plants may be found at several locations within the park, the only known fruiting population exists at the Hampson Property (the junction of Parkway and Highway 199). Small shrubs were pulled, and will continue to be pulled, from the campground and other areas (e.g., west of Leiffer Loop and along Wellman Trail) when encountered. Some holly remains in the ivy infestation north of Highway 199 and east of Kings Valley Road. The large population requires major removal, as detailed in CEQA# 00635A-014. The CEQA and grant noted in the English ivy section cover holly removal in Jedediah Smith Redwoods State Park. Please reference that paragraph, and/or those documents, for additional information. Greater periwinkle (Vinca major) The only known population of periwinkle in JSRSP occurs around the Hiouchi Information Center. Some periwinkle was removed as part of the ivy project begun last year, but much remains; it will be treated with the ivy. Cherry (Prunus species) A mature population of cherry trees (sour or sweet) occurs at the Hiouchi Information Center. Saplings were found in the woods around the information center and as far away as Campsite 70. Consideration should be given to controlling cherry trees before they spread further. Silver wattle (Acacia) (Acacia dealbata) A large population of acacia trees occurs in the park across from the Hiouchi Information Center (at the service road). Saplings were found around the fire cache housing, in Hiouchi Flat, and as far away as the base of the winter boat launch in the campground. Serious consideration should be given to controlling acacia before it spreads further. 3 White sweetclover (Melilotus alba) A large infestation of white sweetclover occurs on the gravel bar. Control was begun this August; a crew used weed wrenches to pull two truckloads from the area west and north of the seasonal footbridge at the campground. Follow-up and additional control is needed. The plant also grows roadside in a few areas of the park. Butterfly bush (Buddleja davidii) An expanding infestation of butterfly bush occurs on the gravel bar. Control was begun this August; a crew used weed wrenches to pull smaller shrubs from an area west of Campsites 58-62. The ground was too hard, and some shrubs too large, to remove all the plants; for these, flowering branches were removed. Follow-up and additional control is needed, possibly with a truck and winch. Crocosmia (Crocosmia x crocosmiiflora) This is a new plant for the park. Small populations occur roadside along Highway 199 just east of the campground entrance, and along Aubell Lane. Another plant was seen by the turnout for the westbound lane of Highway 199 at the 1.55-mile marker, but it may be a waif. Crocosmia is very invasive in Del Norte County, and these populations (as well as those along the Nickel Creek Campground/Enderts Beach Trail) bear watching. Black nightshade (Solanum nigrum) This, too, is a new plant for the park. A small population was found in the burn meadow, in last season’s burn pile. The plants should be monitored, and probably removed. Mode of introduction is unknown; investigation may be warranted. 4 SOUTH DISTRICT Natalie Reed, Biological Science Technician August 24, 2000 European Beachgrass (Ammophila arenaria) Continue to sweep the beach at Freshwater Spit for resprouts every 2-3 weeks. We have used about half of the contract money for the CCC’s, so 270 more CCC person-hours can be spent on removal. This translates into about 4 more days of 10-person crews working 6 hours. Beachgrass locations north of the RV parking area are marked with pink flags. The southern half of the beach is not marked due to high visitor use, so it is best to sweep the entire area for resprouts. Remove the vegetation and bring it to the Mitchell residence to burn on a burn day when the vegetation is dry. Scotch Broom (Cytisus scoparius) Broom removal in the Bald Hills is paused due to the compactness of the soil. Because the prairies are unlikely to burn this year, a concentrated effort was made to remove all Scotch broom (especially those in flower) in all prairies. Areas in need of treatment next year can be found using the air photos with overlays. Cape Ivy (Delairea odorata) Wilson Creek should be swept for resprouts and seedlings every few months. I haven’t checked since late spring, but it does seem relatively slow to re-sprout. The CDF crew was quite thorough in early spring at this site. We attempted to brush cut and scrape the ground in the area with a heavy cape ivy infestation. However, it was difficult to gather the vegetation after brush cutting because of the scattered small leaf fragments which could potentially re-root. I would suggest hand pulling the Cape ivy next year. Leave the cape ivy at the site where it was gathered to burn after it is dry. English Ivy Wilson Creek should be swept for resprouts and seedlings every few months. I haven’t checked since late spring, but the ivy does seem relatively slow to re-sprout. The CDF crew was quite thorough in early spring at this site. Sweep Marshall Pond for resprouts and seedlings every few months. Remember that this is a noiserestricted area during nesting season of marbled murrelets. A few pampas grass plants were pulled at this site this year as well. A small English ivy infestation occurs about 1.2 miles past the gate on Westside Access Rd. When coming from SOC, at this mileage, there is a large Douglas-fir wolf tree on the left-hand side of the road. Park there and look on both sides of the road for ivy seedlings and resprouts. At Redwood Creek, a small infestation of English ivy occurs behind the parking area to the left of the trailhead. There is some ivy growing on a downed log, so it may be warranted to schedule a support crew day for this project. Tansy Ragwort (Senecio jacobaea) A half day with the YCC’ s were spent pulling tansy in the Bald Hills near Williams Ridge Rd. (in drainage near entrance to road) and beneath lookout rock near Robber’s Gulch Rd. Flower heads were cut and bagged to be burned and plants were pulled and left on site. A location of tansy was found recently at Freshwater spit near Kiosk E, but was not removed. Diona Roja had advised me of a tansy location on Wolf Creek road just past the bridge going toward the outdoor school. The area was checked several times, but no tansy was found. 5 Fennel (Foeniculum vulgare) About 20 fennel plants were pulled along the north end of Newton B. Drury road, from the highway entrance to the beginning of Boyes Prairie in Prairie Creek Redwoods State Park. Yellow Starthistle (Centaurea solstitialis) Two previous yellow starthistle locations were surveyed several times this year. These are 1) the gravel pit at Elk Camp prairie and 2) along Long Ridge Road (0.7 miles from intersection of Lyon’s Ranch Rd. and in adjacent drainages). No yellow star thistle was found this year. Note that while much of the gravel from the gravel pit was moved, the portion that contained yellow starthistle still remains. Spanish Heath (Erica lusitanica) About 30 plants were pulled at the south end of Freshwater Lagoon. None were flowering. Check this area for seedlings next spring. Foxglove (Digitalis purpurea) SOC Road is the only area in the park that foxglove was a target control species, though some were pulled around the Scotch broom areas in the Bald Hills. A heavy infestation was present. Plants were handpulled, taking precaution due to the high toxicity of the species. Bull thistle was also controlled along the road and SOC compound. White Sweetclover (Melilotus alba) This plant was controlled at Freshwater near the picnic area and north by Redwood Creek Estuary. It was also pulled out of the gravel pit near Elk Camp prairie, though this portion of the gravel pit has since been removed. Yellow Bush Lupine (Lupinus arboreus) About 15 yellow bush lupine plants were removed from the Freshwater picnic area. Some apparent hybrids were removed as well (those that have both white and purple flowers). 6 ELK MEADOW Jim Popenoe, Soil Scientist November 14, 2000 Elk Meadow warrants special comment because of the extent of the efforts to control invasive plants in one small place. Two facts that made the efforts at Elk Meadow out of the ordinary were that 1. The primary objective of invasive plant control in this case was to reduce interference with successful landscaping and ecological restoration, and Several of the species being removed had not previously been managed as high priority species. 2. The Elk Meadow project received extra attention because it was expected to be so much in the public eye. Earth moving was by far the most dramatic and visible part of the project in FY2000. When this work was done, it exposed seven acres of unvegetated ground to potential plant invasion. Approximately half of the exposed acreage was earmarked for the public day use area, and the remainder was to be restored to a wetland and riparian woodland. The restoration site was planted with natives and weeded during FY2000, but landscape planting in the day use area was postponed until FY2001, creating a wider window of opportunity for colonization by invasive plants. Considerable effort was expended to control invasives in FY2000, and the kinds of potentially troublesome plants differed between the restoration and day use portions of the project area. In both, "hog fuel" mulch was applied, in part, to slow invasive plants. Restoration Site The FY2000 revegetation progress report also describes efforts to control invasive plants on the restoration site. In most projects in RNSP, the dispersal of seed from native trees initiates a trajectory of succession generally toward native forest with little or no active intervention needed. However, it was suspected that succession might proceed differently on a floodplain with pastures: 1. Flooding would disperse propagules of aggressive non-natives from the nearby pastures. 2. Aggressive pasture plants would inhibit establishment of native trees and slow their growth. 3. Once established, aggressive pasture plants might exclude native vegetation for a long time. Much attention was focussed the first year on establishing trees and shrubs and on removing aggressive pasture plants. Since pasture plants are shade intolerant, the effort needed to remove these exotics seems likely to decrease as the tree and shrub canopy closes. The restoration site was first hand-weeded in November 1999 (40 person-hours). The next weeding was in early March 2000 (40 person-hours). The weeding effort increased dramatically in spring and early summer. From April 18 to July 6, 2000, 504 person-hours were expended weeding on the floodplain, then 40 person-hours in September, 2000. The total effort for weeding the first year was 624 person-hours. Given an uncertain outcome, a monitoring protocol was established to measure results and refine efforts. In June, five transects were established to quantify the development of cover and species composition on the floodplain. The transects were monitored on June 17 and again on August 22. A figure on page 8 summarizes the monitoring results. Data for individual species are presented in the FY2000 Elk Meadow revegetation progress report. 7 June 17, 2000 August 22, 2000 Vegetation cover on the floodplain based upon 480 sample points along five transects. Certain pasture species were particularly troublesome on the floodplain portion of the restoration site during the first project year: Reed canarygrass (Phalaris arundinacea) Reed canarygrass is a wetland obligate that grows up to 10 feet (3 m) tall at the Davison Ranch. It spreads vegetatively via shallow rhizomes, and it overtops and out-competes smaller plants. Reed canarygrass is highly productive livestock forage, although plants become relatively unpalatable, with tough stems and high silica and alkaloid content, as they mature. In pastures, very heavy spring cattle grazing can keep reed canarygrass from out-competing other plants. If it becomes overly dominant, many ranchers plow and seed with more palatable grasses. With the removal of the dairy cattle from the Davison Ranch in 1992, reed canarygrass was effectively released. The elk seem not to eat it while the plants are tall and green, so they may further its competitive advantage. Reed canarygrass is best adapted to a water regime in which the depth of water fluctuates widely and irregularly. At the Davison Ranch, this species occurs all along the banks of Prairie Creek, and it has become dominant in wetlands with artificial drainage. Although growth and spread is limited to times when the soil is both moist and well aerated, it withstands long and/or irregular periods of waterlogging. Once established, reed canarygrass is tenacious, and it may persist even after an altered hydrologic regime is normalized. In 1997, a culvert artificially draining the oxbow north of the Davison Ranch causeway was removed. The culvert had let water drain quickly from the oxbow, artificially shortening the hydroperiod. The oxbow was populated almost entirely by reed canarygrass. After the culvert was removed, water remained in the oxbow continuously through the end of spring. Although a normal hydroperiod was restored, little change in reed canarygrass cover occurred between 1997 and 2000. One abandoned pasture near the mouth of Skunk Cabbage Creek has been continuously dominated by reed canarygrass since 1986. Reed canarygrass is thought to have some populations native to California. Whether or not it is native to California's north coast (and at the Davison Ranch in particular) is unclear. If it is native, Mr. Davison's clearing of the floodplain to pasture allowed it to expand its extent, much as Euro-American fire suppression allowed Douglas-fir to expand into the prairies and oak woodlands. Reed canarygrass was controlled at Elk Meadow restoration site to allow the former native riparian and wetland plant associations to reestablish, not necessarily because it was earmarked as an exotic species. Roughly 5 percent of weeding efforts on the restoration site were spent removing reed canarygrass. Crews dug up the plants and rhizomes, using a technique similar to that used to control European beachgrass. After three-to-four follow-ups, re-sprouts were no longer found. This method was labor intensive, and it 8 was practical only for controlling scattered individual plants. Follow-ups should be continued on the restoration site to keep the reed canarygrass under control. The effort necessary to accomplish this is expected to diminish as the wetland natives increase their height and coverage of the ground. The extent and degree of infestation of reed canarygrass should be mapped out parkwide, perhaps emphasizing the Prairie Creek watershed. Reed canarygrass threatens native riparian and wetland ecosystems in the Pacific Northwest (Antieau 2000), and the survival of salmonids returning to spawn (Carrasco 2000). It is a strong candidate to become a high priority species for control in RNSP. Creeping bentgrass (Agrostis stolonifera) Creeping buttercup (Ranunculus repens) White clover (Trifolium repens) After reed canarygrass, creeping bentgrass, creeping buttercup, and white clover, proved to be the most aggressive and troublesome pasture exotics on the restoration site. A common feature of all these species is that they spread by stolons (above-ground stems), rooting at the nodes. They rapidly colonized bare ground by this mode of spread. Once these plants achieve dominance, they preempt space from riparian native tree and shrub seedlings. In addition, they attract elk, which then eat the riparian natives along with trimming the pasture plants. Bentgrass and buttercups persist as a major component of the abandoned pastures on the Davison Ranch. Bentgrass also infests Strawberry Creek near SOC. The channel is so choked with grass that fish are excluded. White clover was abundant when the park acquired the Davison Ranch in 1992, but without the dairy cattle, the clover has largely succumbed in competition with taller pasture species. The strategy to control creeping pasture plants on the restoration site was to remove them while they were few and small. Roughly 80 percent of weeding efforts on the restoration site were spent removing the bentgrass, buttercups, and clover by hand. This method was labor intensive, and was practical only for controlling scattered individual plants. The labor available proved insufficient to remove all of the plants and, as the figure shows, the cover percentage of pasture plants increased in spite of the weeding effort. The growth of creeping pasture plants the first year exceeded the park's capability to manually control them. Herbicide might have been more effective and efficient. Because these plants all have thin cuticles, they are susceptible to herbicide at low concentration. In addition, with translocation via the stolons, herbicide applied to any part of a plant affects the whole. In August, treatment with glyphosate was proposed but rejected. It appeared unlikely that a biological assessment and opinion could be completed in time to carry out the work before the first rains. By September, only bentgrass was removed, and then only where it was spreading into the pond. What will happen if further control actions are impracticable? In the pastures at the Davison ranch, creeping bentgrass and creeping buttercups occur as facultative wetland dominants around the margins of ephemeral pools. Unlike reed canarygrass, these two species are small in stature, so may persist, but are unlikely to displace native emergent wetland plants. Pasture plants generally do exclude tree seedlings. The window available for natural recruitment by native tree seedlings closes when bare ground is no longer available for colonization. If natural recruitment fails, the park may need to invest more in planting native trees in order to reestablish the riparian zone along Prairie Creek. The FY2000 Elk Meadow revegetation progress report suggests some methods. Since a grass-choked channel may exclude fish, park staff need to be alert for bentgrass that may creep out into the pond. The situation bears watching. Other species Remaining efforts (about 15 percent) were spent removing other targeted exotic species from the restoration site. The most abundant of these were Himalaya berry (Rubus discolor), bull thistle (Cirsium vulgare), and foxglove (Digitalis purpurea). The effort necessary to control these species is expected to diminish as the amount of remaining available bare ground available for colonization decreases. 9 Day Use Area Creation of the new Day Use Area opened roughly 3.5 acres of unvegetated ground to plant invasion. As with the restoration site, the situation offered a chance for management actions the first year to prevent an escalating weed problem. The site will remain vulnerable, require continued close monitoring, and may require major control efforts for several years. The total weeding effort here in FY2000 was 340 personhours. A rough estimate of percentage effort by species is shown. Himalaya berry (Rubus discolor), 35 percent The labor necessary to control Himalaya berry is expected to decrease with time. Most of the plants were re-spouts, and the treatment was to remove their burls. Next, root fragments will re-sprout, but repeated follow-ups can kill most of these plants within about a year. Poison hemlock (Conium maculatum), 25 percent The poison hemlock may have a persistent seed pool. The plants should be pulled each year early before they have an opportunity to flower. English ivy (Hedera helix), 25 percent Climbing English ivy was removed from around the base of a dead redwood stump next to Davison Road near the barn. The aerial ivy did not die. Apparently, roots grow through the dead stump. This infestation requires a follow-up on the top of the stump to kill the aerial ivy in the Sitka spruce tree. Bull thistle (Cirsium vulgare), 10 percent Bull thistle seeds have a lifespan of only a few years, and the species colonizes primarily by wind dispersal. Thistles were removed from areas of newly bared ground to prevent a seed buildup in the soil. Preventative follow-up is important until the amount of available bare ground available for colonization is minimized. White sweetclover (Melilotus alba), 5 percent Sweetclover seeds are often present in river run gravel, and they have a long lifespan. Sweetclover plants were removed from around new roads and trails. Additional sweetclover seed may have been present in gravel delivered this past summer. If so, the effort needed to control this species may increase. Since each mature plant introduces thousands of new seeds into the soil, sweetclover should be removed early before flowering. Regular preventative follow-up is important until the seed pool becomes exhausted. The cost of removing sweetclover and other weeds should be considered when gravel is purchased by RNSP. It may be less costly for the park to adopt a policy of purchasing only weed-free gravel than to continue buying possibly cheaper gravel but having to follow up with years of labor intensive weed pulling. Literature Cited Antieau, C.J. 2000. Biology and management of reed canarygrass, and implications for ecological restoration. Washington State Department of Transportation, Seattle, WA. http://www.halcyon.com/sernw/docs/RCG.rtf Carrasco, K. 2000. Coho pre-spawn mortalities in a flooded reed canarygrass habitat. In Final Proceedings (abstracts) of reed canarygrass working group conference, March 15, 2000. USDA-FS Olympic National Forest, Olympia, WA. http://www.halcyon.com/sernw/docs/RCG2000.rtf 10