Gold Ray Dam Invasive Vegetation Survey Introduction For any major landscape project to stand a chance of being successful and realistic, it requires adequate inventory of resources, and consideration of probable outcomes based on planned actions. Rogue Valley Council of Governments, overseeing the removal of Gold Ray Dam has, through this contract, requested the inventory, mapping, and photographing of vegetation, specifically alien invasive weeds, within six mapping areas (Appendix A), as well as making prioritized recommendations for treatment of the weeds and management of the vegetation. Recommendations for practical alternatives will also be offered in this document. This contract required all streamside vegetation to be identified, as well as the vegetation along six 100 ft. linear transects, one in each of the six designated areas (Appendix B). Narratives, illustrations, and photographs will be presented by area, while recommendations will be based on the project area as a whole. In a situation like this, with the alien invasive weed species intermingled within a diverse native environment, it is critical that we keep an open mind to management options possibly not considered before. METHODS Shorelines of the entire project area were viewed from a drift boat. The project area was divided into six survey areas. Dominant vegetation visible along the shoreline was recorded, including noxious weeds. Each vegetation type was photographed, and recorded a GPS waypoint for each of the photo-points. Within each survey area, dominant vegetative cover was recorded along a 100-foot-long. In most cases this required cutting a swath into dense vegetation using a machete. Photographs were taken at various points along each transect. Another photo was taken from the boat showing the entrance to each transect, which was marked with red and yellow flagging, tied conspicuously to a branch at the shore. The GPS waypoint can be considered the permanent marker for the beginning of each transect, because it is likely that this flagging will not be discernable in a year’s time. The flagging bears the transect number, latitude and longitude, and the transect azimuth from that point. 1 Section I. List of observed and potential noxious weeds for the GRD survey area. Species observed are in bold type. Garlic mustard (Alliaria petiolata) Yellow flag iris (Iris pseudacorus) Purple loosestrife (Lythrum salicaria) Himalayan blackberry (Rubus armeniacus) Poison hemlock (Conium maculatum) Yellow nutsedge (Cyperus esculentus) St. Johnswort (Hypericum perforatum) Canada thistle (Cirsium arvense) Bull thistle (Cirsium vulgare) Diffuse knapweed (Centaurea diffusa) [along Upper River Road near Gold Hill] Yellow starthistle (Centaurea solstitialis) Spotted knapweed (Centaurea stoebe) [along Kirtland Road near Bear Creek] Meadow knapweed (Centaurea moncktonii) [downstream on Rogue River] Rush skeletonweed (Chondrilla juncea) [present along I-5 in Jackson County] False brome (Brachypodium sylvaticum) Johnsongrass (Sorghum halepense) Pampas grass (Cortaderia jubata) Flatpea (Lathyrus latifolius) Puncturevine (Tribulus terrestris) Spiny cocklebur (Xanthium spinosum) Dyers woad (Isatis tinctoria) Leafy spurge (Euphorbia esula) Scotch broom (Cytisus scoparius) Spanish broom (Spartium junceum) French broom (Genista monspessulana) Japanese knotweed (Fallopia japonica) Other Invasive Species Found Reed canarygrass (Phalaris arundinacea) Cultivated grape (Vitis vinifera) Common teasel (Dipsacus fullonum) Dog rose (Rosa canina) Jimsonweed (Datura stramonium) Tree of Heaven (Ailanthus altissima) 2 Section II. Vegetation survey Area #1 Rogue River Right bank: Dominant vegetation includes Himalayan blackberry (Rubus armeniacus), Oregon ash (Fraxinus latifolia), willows (Salix exigua, S. lucida, S. lasiolepis, S. sessilifolia), chokecherry (Prunus virginiana), red-osier dogwood (Cornus sericea), brown dogwood (Cornus glabrata) and syringa (Philadelphus lewisii). Climbing over the top of this vegetation were assorted vines: escaped cultivated (feral) grapes (Vitis vinifera), native grape (Vitis californica), California greenbriar (Smilax californica), orange honeysuckle (Lonicera ciliosa) and woodbine (Parthenocissus vitacea). The dominant grass was reed canarygrass (Phalaris arundinacea), which occurred mostly in dense patches along the shoreline, sometimes intermingled with cat-tails (Typha latifolia). Broad-leaved forbs included poison hemlock (Conium maculatum), deadly nightshade (Solanum dulcamara), St. Johnswort (Hypericum perforatum), black mustard (Brassica nigra), bull thistle (Cirsium vulgare), sweet clover (Melilotus) and bladder campion (Silene latifolia ssp. alba). Photo 8a (waypoint 19): Blackberry bushes with California greenbriar vines overtopping them. Photo 9a (waypoint 19): Red-osier dogwood at water’s edge. Common vegetative combinations were blackberries or red-osier dogwood overtopped with feral grapes or smilax. The most common trees were Oregon ash, and shining and narrow-leaf willows. The shoreline along this reach of the river was a dense, almost impenetrable mass of various native trees, and exotic and native shrubs and vines. Narrow-leaf and sandbar willow (Salix sessilifolia) dominate the island. Near the entrance to Kelly Slough is a small inlet. Here we found several invasives, purple loosestrife (Lythrum salicaria), yellow flag iris (Iris pseudacorus), and Canada thistle (Cirsium arvense) in small patches along the shoreline, growing among reed canarygrass and cattails. The primary trees and shrubs here are native willows, red-osier dogwood, Oregon ash. 3 Photo 15a (waypoint 20): purple loosestrife in the inlet, growing with reed canarygrass and cattails. Left Bank: This area has somewhat less blackberry along the shore and more willow, Oregon ash, red-osier dogwood, and hardhack (Spirea douglasii). Along the shoreline are patches of cattails, reed canarygrass, and torrent sedge (Carex nudata). The vines are primarily woodbine and feral grapes. Transect for Area #1 at waypoint 26. Azimuth of 210º. Vegetation in Transect #1: reed canarygrass, purple loosestrife, water smartweed, cluster dock, deadly nightshade; blackberries, woodbine, Oregon ash, native and feral grapevines, California greenbriar, native willows, poison hemlock, gooseberry (Ribes sp.), creeping jenny (Lysimachia nummularia), Douglas sagewort (Artemisia douglasiana), awl-fruit sedge (Carex stipitata), whiteroot sedge (Carex barbarae). The most important invasive species in this transect is garlic mustard (Alliaria petiolata). Photo 34a Photo 39a 4 Kelly Slough Area #2 Invasive species found along the shoreline in Kelly Slough were yellow flag iris, purple loosestrife and Canada thistle. The iris and the loosestrife were also present on the small island, which was dominated by willows. Photo 17a (waypoint 21): entering Kelly Slough. Photo 21a (waypoint 23): purple loosestrife and yellow flag iris. Photo 22a (waypoint 24): banks of Kelly Slough showing willows, cattails, reed canarygrass, yellow flag iris and loosestrife Transect #2 in open area, vegetation (species in order of descending abundance) cattails reed canarygrass purple loosestrife yellow flag iris red-osier dogwood willows broadfruit bur-reed (Sparganium eurycarpum) clustered dock (Rumex conglomeratus) water smartweed (Polygonum amphibium) water speedwell (Veronica anagallisaquatica) rush (Juncus sp.) annual rabbitsfoot grass (Polypogon monspeliensis) 5 Photo 28a (waypoint 25): transect vegetation. Photo 30a (waypoint 25): seed capsules of yellow flag iris (Iris pseudacorus). Photo 31a (waypoint 25): purple loosestrife. 6 Tolo Slough Area #3 Entering the slough, the banks are a nearly solid wall of blackberries, with overhanging Hinds walnut (Juglans hindsii), then it opens up into more willows and Oregon ash, and red-osier dogwood. The native and feral grapes have climbed up over the willows and blackberries, in particular. Photo 43a (waypoint 28): Tolo Slough. Photo 46a (waypoint 28): Yellow flag iris along shore in Tolo Slough. Photo 51a (waypoint 29): Yellow flag iris along shore in Tolo Slough. Transect #3: At water’s edge, yellow flag iris, purple loosestrife, cattails, reed canarygrass; small amounts of water speedwell, bur-reed, dock. Inland more reed canarygrass, then willow, red-osier dogwood, and Oregon ash creating dense shade, without understory forbs. 7 Photo 55a (waypoint 30): Transect for Tolo Slough (Area #3). All of Tolo Slough has intermittent yellow flag iris and loosestrife along the shoreline. Rogue River Area #4 Right bank: Hinds walnut and Oregon ash and white alder (Alnus rhombifolia) form the tree overstory closest to the water with an understory of blackberries, narrow-leaf and shining willow, red-osier dogwood, brown dogwood, chokecherry, syringa, hawthorn (Crataegus suksdorfii), spirea and ninebark. Climbing over the shrub and tree canopies are California greenbriar, native and feral grapevines, Western white clematis (Clematis ligusticifolia), and orange honeysuckle. Graminoids include reed canarygrass and whiteroot sedge. Forbs present were moth and common mullein (Verbascum blattaria, V. thapsus), poison hemlock, sweetclover, soapwort (Saponaria officinalis), Douglas mugwort, nettles (Urtica dioica), St. Johnswort, deadly nightshade, purple loosestrife, common teasel (Dipsacus fullonum), bladder campion, and bull thistle. 8 Photo 4a (waypoint 16): Ninebark along the river. Photo 15b (waypoint 36): Reed canarygrass along water edge with blackberries and red-osier dogwood forming a wall on the bank. Photo 5a Red-osier dogwood with California greenbriar along the river (waypoint 17) Photo 18b (waypoint 36): Dog rose (Rosa caninum) is the dominant shrub for a short distance. This rose is the aggressive weedy shrub near Immigrant Lake; this was the only location were it was observed in the survey area. 9 Photo 21b (waypoint 36): Red-osier dogwood is the dominant shrub. Photo 27b (between waypoints 37 and 38): native grapevine over red-osier dogwood. Photo 24b (waypoint 37): Native grapevines over the trees. 10 Photo 28b (between waypoints 37 and 38): native grape and smilax over blackberry. Photo 29b (between waypoints 37 and 38): native grape over red-osier dogwood. Transect #4: Waypoint 32. Azimuth 220º. A white alder overhangs the shoreline here, with syringa an important understory shrub, but not as abundant as the Himalayan blackberries. California greenbriar, grapevines, honeysuckle and clematis climb over all the woody vegetation. Poison hemlock and reed canarygrass are major non-natives here. Native plants include nettles, snowberry (Symphoricarpos), gooseberry, chokecherry and blue wildrye. In the understory were copious amounts of garlic mustard, scattering seeds everywhere at the slightest touch. 11 Photos 73a-74a (waypoint 32): transect #4 vegetation described above. Left bank: A solid wall of Himalayan blackberries is overlain with California greenbriar, and grapevines. Interspersed with the blackberries are large clumps of red-osier dogwood, also overlain with vines. Oregon ash, bigleaf maple (Acer macrophyllum) and Hinds walnut occur here, and farther from the water’s edge are black cottonwood trees (Populus trichocarpa). Non-woody species include birdsfoot trefoil (Lotus corniculatus), soapwort, and bladder campion. Photo 1b (waypoint 33): solid patches of reed canarygrass between the shrubs and the water. Photo 3b (waypoint 34): native grapevines trailing over blackberry and red-osier dogwood. 12 Photos 7b-8b (waypoint 35): examples of escaped cultivated grape climbing over the tops of native trees (probably Oregon ash), and completely covering them. Other native trees in photo include Hinds walnut, white alder and black cottonwood. Photo 11b (waypoint 36): feral grape covering Himalayan blackberry bushes with poison hemlock protruding through. Rogue River Area #5 Right bank: Cattails, sedges, reed canarygrass, willows, blackberries, and grapevines; occasional poison hemlock, deadly nightshade, Canada thistle. 13 Photo 41b (between waypoints 39 and 40): reed canarygrass with thistle and clumps of cattails are interspersed with blackberries and grapevines; black cottonwoods are the tall trees back from the river. Photo 105b (below waypoint 44): Canada thistle with reed canarygrass and poison hemlock. 14 Photo 109b (waypoint 45): cattails and willows, then blackberries with reed canarygrass along river bank. Transect #5 Waypoint 44. Azimuth 300º. The first 50 feet is reed canarygrass with a few narrow-leaf willow, all overtopped with feral grapevines; a few plants of nightshade and poison hemlock. The second 50 feet of transect is a solid stand of Himalayan blackberry, overtopped with feral grapevines. 15 Photos 99b & 97b (waypoint 44): transect vegetation, as described above. Left bank: Most of this stretch of the river borders tall fescue pastureland, where the vegetation is either pasture weeds (poison hemlock, teasel, Canada thistle) or a narrow line of Himalayan blackberry and reed canarygrass. At the mouth of Bear Creek there is more purple loosestrife, some horsetail (Equisetum), yellow nutsedge (Cyperus esculentus), native willows, and a variety of grasses, sedges, and rushes (Scirpus microcarpus, Eleocharis palustris, Juncus effusus var. pacificus, Juncus acuminatus, Agrostis stolonifera). Photo 35b (waypoint 38): snowberry grows between the field and the edge of the river. Photo 38b (waypoint 39): St. Johnswort between the field and the edge of the river. Photo 42b (waypoint 40): mouth of Bear Creek. Willows and St. Johnswort where the bank is sloughing. Photos 43b-44b (waypoint 40): the left bank of Bear Creek is steep and sloughing off with teasel and other weedy vegetation as well as Equisetum along the water edge; the right bank is gentle with wetland vegetation, including sedges, rushes, bulrushes and willows. 16 Photo 48b (waypoint 40): the wetland vegetation at the island at the mouth of Bear Creek included vigorous stands of purple loosestrife. Rogue River Area #6 Right bank: A solid wall of Himalayan blackberry lines the river, interspersed with tree and shrub willows, and red-osier dogwood. A native rose (Rosa) is present in this area. Nettles, reed canarygrass and poison hemlock are also common. Photo 50b (just north of waypoint 40): wall of blackberries with vines. 17 Photo 77b (waypoint 43): St. Johnswort and bladder campion in blackberries and dense vegetation on banks. Photo 80b (waypoint 43): looking downstream; dense wall of impenetrable shrubs. Photos 84b, 90b (between waypoints 43 and 44, looking downstream): blackberry bushes and vines. Transect #6 Waypoint 41. Azimuth for transect is 160º. The transect starts under a large native hazelnut (Corylus cornuta) tree overhanging the shore. The understory shrubs include snowberry, syringe, red-osier dogwood, ninebark, 18 and gooseberry. Adjacent trees are Oregon ash. Vines are primarily western white clematis and California greenbriar. Abundant garlic mustard grew under this multilayered canopy and was spreading copious amounts of seed when disturbed. Photo 58b (waypoint 41): transect vegetation as described above. 19 Garlic mustard in flower; most plants had ripe seed. Island: This was dominated by native willows and reed canarygrass, but we noted a single young catalpa (Catalpa speciosa) tree that had become established and was several feet tall. Photo 69 (waypoint 42): view of the island. Photo 72b (waypoint 43): catalpa tree on island. 20 Left bank: Native trees included black cottonwood, Oregon ash, and native willows. Parts of the bank was a wall of Himalayan blackberry with intermittent red-osier dogwood, with grapevines and sometimes greenbriar, but there were also areas were black mustard, poison hemlock, mugwort, bladder campion, great hedgenettle (Stachys cooleyae), St. Johnswort, deadly nightshade and birdsfoot trefoil found some sun to thrive. Summary The Rogue River upstream from Gold Ray Dam was, by design, an area of slow-moving water (particularly Tolo and Kelly Sloughs). Materials carried downstream with the current tended to settle out and remain there until floods carry them further downstream. Included in the sediments are seeds and other fragments of plants such as roots, branches, leaves, fruits. The survey area shown on a map on page 3 contains a mixture of native and introduced species, some which were part of the existing landscape (before the dam), while others arrived later via water (downstream flow or clinging to boats), air (wind or waterfowl), or were transported by wild or domestic animals or humans. The reasons why certain plants are currently found in association with others may not be obvious by casual observation, but are likely related to several factors, including biology of the species, availability of key resources (light, water) and to timing of introduction (i.e., when a particular plant or propagule found its way to the pond). Once introduced to favorable habitats, they intermingled with existing resident plants, and became part of the vegetative community as their populations expanded. Plant associations in the survey area are complex, but there are some patterns based on relative availability of water and sunlight, and frequency of disturbance. For example, some species such as purple loosestrife, yellow flag iris and reed canarygrass were seen primarily in full sun along the wet shoreline or in shallow standing water. Others, including the native willows are well adapted to rapid colonization following flood scouring and deposition, so were often seen along shorelines exposed to these events, including islands. Vines, both native (honeysuckle, smilax, native grape) and non-native (woodbine and cultivated grape) ascend through existing canopies to access the sunlight they require. Others species are more shade-tolerant, including garlic mustard, which was found even under dense canopies of Himalayan blackberry. The native tree community is segregated primarily by the water table; e.g., Hinds walnut grows with Oregon ash in openings on depositional floodplains with a consistently high water table, while black cottonwood, as the tallest tree, forms the dominant canopy of the floodplain woodland, even a considerable distance from the current shoreline. Because introduced and native species are so intermingled, treatment and/or control of the invasive species without harming desirable vegetation would be difficult. 21 Conclusions Treatment and management of the former impoundment area behind Gold Ray Dam will not be easy, nor will it be quick. There are now, and will be, different forces at work than prior to removal of the dam (e.g., rapidly moving water, through traffic by boats, higher level of human interface). The open, newly exposed mudflats are especially vulnerable to invasion by a host of candidates; not least of which are those located on immediately adjacent lands. Areas farther back from previously standing water (the periphery of the green zone) may lose subsurface water, changing from a subirrigated to a well-drained, dryland environment. Both Kelly and Tolo Sloughs drained in August 2010, a time at which many annual and perennial plants were producing seed. Daily afternoon winds, typical in southwestern Oregon, can be expected to carry seeds from these ruderal species onto the newly exposed mudflats, where many will germinate and become established. This situation should not come as a surprise, nor should it cause much alarm. If prompt action is taken to establish competitive, desirable species, the presence of annual weeds is likely to be relatively short-lived (in the absence of further disturbance). In addition to immediately adjacent plants colonizing this newly exposed setting, noxious weeds upstream of the ponded area (species not currently observed in the contract area) may be moved downstream. Thus, the area should be monitored for new invaders, which should be treated when found. Some of those species are listed on pages 3 and 4 (in regular, not bold type). Recommendations Little or no action should be taken without a clear idea and understanding of what future vegetative cover of the project area is desired. Short-term and long-term vegetation management goals should be established within a landscape plan. Widespread and uncoordinated treatments in the project area prior to the creation of a landscape plan may result in irreversible damage, or at the very least, expensive, redundant projects. Recommended short-term goals might include: Consult with landowners with regard to desired outcome in landscape vegetation; Prevent garlic mustard, yellow flag iris, and purple loosestrife from occupying the newly exposed mudflats; Collect seeds and/or cuttings or ‘slips’ of desired native trees (e.g., willow, white alder, hawthorn, hazelnut, black cottonwood Hinds walnut, Oregon ash) in preparation for planting; [Frank Callahan, local seedsman and president of the Siskiyou Chapter of the Native Plant Society of Oregon, is exceptionally knowledgeable on the ecology of riparian woodlands in Jackson County, and 22 would be a good individual to consult when developing a landscape vegetation plan.] Collect seeds of native shrubs (ninebark, red-osier dogwood, smooth dogwood, snowberry, gooseberry, chokecherry) for out-planting in preparation for establishment with the tree species; Submit grant proposals for rehabilitation funds of newly exposed areas; If photo-points were not previously established for key treatment areas, this should be done soon. They will help monitor success/failure, as well as establish historical references. Recommended long-term goals might include: Contracts for survey and treatment of undesirable plant species, focusing on new invaders; Contracts for planting tree and shrub ‘slips,’ plugs, or seedlings; Armoring of ‘at-risk’ banks and exposed slopes; Agreements with landowners for long-term management, including weed treatment, on adjacent lands; Strong consideration should be given to reed canarygrass as a temporary dominant species in the newly exposed mudflats. Although this grass is not native, it is already widespread and is a highly competitive dominant in the area, excluding annual weeds and many invasive perennials. It is also a superb bank stabilizer, and is not on Oregon’s A, B, or T list of noxious weeds. Where grape plants are climbing large, desirable trees, the grape vines should be severed close to the ground. Heavy masses of grapevines in the upper canopy of desirable trees makes them more vulnerable to windshear of branches, or may result in the entire tree falling in the event of high winds. In terms of treatment of undesirable plant species, certainly a prioritization for time and money is important. For these reasons, as well as the likelihood for success, the following is recommended: Focus the majority of resources on garlic mustard, yellow flag iris, and purple loosestrife. Populations of yellow flag iris and purple loosestrife are relatively small at present, and although there are other populations upstream, which could 23 re-populate the project area, they would establish along the newly created riverbank, not the prior high water line. Garlic mustard is widespread throughout the project site, but the fact that it is a biennial gives control a good chance. Every effort should be made to treat this species prior to seed production. Ultimate success in controlling this species is more likely under this prescription. Because only one Catalpa was seen on the furthest upstream island, that should be removed. If and when Japanese knotweed or spiny cocklebur appear, they should become priority weeds, and targeted for removal. Other species, such as Himalayan blackberry, grape, and yellow nutsedge are so widespread and numerous that the chances for success are minimal. That doesn’t mean they couldn’t or shouldn’t be targeted in the future as part of an overall vegetation management plan, but first efforts should be targeted as stated above. The recent change in environment may be detrimental to existing non-target weeds, and they may be less competitive as a consequence of the drop in water level. 24