The understory impacts and health problems identified during the field survey were trampling of the vegetation, soil compaction, invasive weed infestation, and a loss of species diversity and native plant components. The vegetation trampling results from all types of off-trail traffic (pedestrian, equestrian, and bicycle) with no distinct difference in degree of impact between the types of off-trail traffic. The off-trail traffic causes direct physical impact to the plants as well as soil compaction, which can be a limiting factor for plants (especially the liliaceous species). Off-trail use was noted throughout the trail system. In particular, the flat and gentle slope areas, such as the ridgeline and spur ridges associated with the Ravine and Big Trees trail areas, were heavily impacted (see Figure 5).

Tree Layer:

Acer macrophyllum bigleaf maple
Alnus rubra red alder
Cupressus lawsoniana Port Orford-cedar (planted)
Pseudotsuga menziesii var. menziesii Douglas-fir
Quercus chrysolepis canyon live oak
Sequoia sempervirens coast redwood
Sequoiadendron giganeum giant sequoia (planted)
Ulmus sp. elm (planted and escaped)
Umbellularia californica California bay

Shrub Layer:

Baccharis pilularis coyote brush
Corylus cornuta var. californica California hazelnut
Cytisus scoparius scotch broom (invasive)
Dryopteris expansa spreading wood fern
Duchesnea indica mock-strawberry
Epilobium ciliatum northern willowherb
Equisetum telmateia ssp. braunii giant horsetail
Fragaria vesca wood strawberry
Galium triflorum sweet-scented bedstraw
Gaultheria shallon salal
Genista monspessulana French broom (invasive)
Hedera helix English ivy (invasive)
Holcus lanatus common velvet grass
Hypochaeris radicata hairy cat's-ear
Ilex aquifolium English holly (invasive)
Iris douglasiana Douglas iris
Juncus effusus common rush
Juncus patens spreading rush
Lactuca virosa wild lettuce
Lathyrus sp. pea
Lonicera hispidula var. vacillans hairy honeysuckle
Marah fabaceus California man-root
Mimulus aurantiacus orange bush monkeyflower
Myosotis latifolia forget-me-not
Osmorhiza chilensis mountain sweet-cicely
Oxalis oregana redwood sorrel
Oxalis pes-caprae Bermuda buttercup
Panicum dichotomiflorum fall panicum
Pentagramma triangularis goldenback fern
Physocarpus capitatus Pacific ninebark
Polystichum munitum sword fern
Pteridium aquilinum var. pubescens western bracken fern
Pyracantha sp. firethorn
Rhamnus californica coffeeberry
Ribes menziesii canyon gooseberry
Ribes sanguineum var. glutinosum red flowering currant
Rosa gymnocarpa wood rose
Rubus parviflorus thimbleberry
Rubus ursinus Pacific bramble
Rumex crispus curly dock
Sambucus racemosa var. racemosa red elderberry
Satureja douglasii yerba buena
Scrophularia californica coast figwort
Senecio mikanioides German-ivy (invasive)
Smilacina racemosa branched Solomon's seal
Smilacina stellata star Solomon's seal
Solanum americanum small-flowered nightshade
Sonchus oleraceus common sow thistle
Symphoricarpos albus var. laevigatus common snowberry
Toxicodendron diversilobum poison-oak
Vaccinium parvifolium red huckleberry
Vaccinium ovatum evergreen huckleberry

Herbaceous Layer:

Actaea rubra baneberry
Agrostis exarata western bent-grass
Asarum caudatum wild ginger
Athyrium filix-femina lady fern
Briza maxima large rattlesnake grass
Bromus sp. brome
Carduus pycnocephalus Italian thistle (invasive)
Carex subfusca rusty sedge
Cirsium vulgare bull thistle (invasive)
Conium maculatum poison hemlock (invasive)
Cynosurus echinatus hedgehog dogtail grass
Cyperus eragrostis nut-grass
Disporum smithii Smith’s fairy bells
Dryopteris arguta coastal wood fern
Stachys ajugoides hedge-nettle
Stachys stricta Sonoma hedge-nettle
Taraxacum officianale common dandelion
Tellima grandiflora fringe cups
Tolmiea menziesii youth-on-age
Torilis arvensis rattlesnake weed
Trillium ovatum western trillium
Urtica dioica ssp. holosericea stinging nettle
Veronica serpyllifolia thyme-leaved speedwell
Vicia gigantea giant vetch
Vinca major greater periwinkle (invasive)
Viola sempervirens evergreen violet

18-19