Plant List and Planting Guidance for Landscape- Based Stormwater Measures
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Appendix BB Plant List and Planting Guidance for Landscape- Based Stormwater Measures Table of Contents B.1 Introduction 1 B.2 General Recommendations 2 B.3 Plants for Stormw ater Measures 3 B.4 Planting Specifications 10 B.5 Monitoring and Maintenance 13 B.6 Bay-Friendly Landscaping and Integrated Pest Management 15 B.7 Nursery Sources for Native Plants 19 References 20 B.1 Introduction The purpose of this appendix is to provide guidance on the planting techniques and selection of appropriate plant materials for the stormw ater measures described in this handbook. The plant lists described in this appendix are not prescriptive, but should serve as a guide. In selecting plant materials, it is important to consider factors that influence plant establishment and success, such as microclimate, type of soil, w ater availability, proximity to saltw ater and exposure to sun. Numerous resources are available to assist in selecting appropriate plant species in Alameda County, including Sunset's Western Garden Book and the East Bay Municipal Utility District’s Plants and Landscapes for Summer-Dry Climates of the San Francisco Bay Region. APPENDIX B B-1 ALAMEDA COUNTYWIDE CLEAN WATER PROGRAM In addition, the function of the individual stormw ater measure should be carefully considered w hen selecting plant materials. Factors to be considered include inundation period, expected flow of w ater, and The pllantt lliistts descriibed iin access and maintenance requirements. tthiis appendiix are nott prescriipttiive,, butt shoulld B.2 General Recommendations serve as a guiide.. In sellecttiing pllantt matteriialls,, iitt Avoid the use of invasive species. In selecting plants for iis iimporttantt tto consiider stormw ater measures, the use of invasive species should facttors tthatt iinflluence pllantt be avoided. A complete list of invasive plants can be found establishment and success, at www.cal-ipc.org, the California Invasive Plant Council’s establishment and success, Invasive Plant Inventory. such as miicroclliimatte,, ttype of soiill,, watter avaiillabiilliitty,, Minimize or eliminate the use of irrigated turf. Effort proxiimiitty tto sallttwatter and should be made to minimize the use of irrigated turf, w hich exposure tto sun.. has higher maintenance requirements and greater potential for polluted runoff. Select California natives and/or drought tolerant plants. Planting appropriate, drought tolerant California natives or Mediterranean plants reduces w ater consumption for irrigations, and reduces mow ing, fertilizing, and spraying. For the purposes of the plant list on the follow ing pages, "drought tolerant" refers to plants that meet the follow ing critieria: . Are identified as drought tolerant as follow s: California Native Plants for the Garden (Borstein, et al.). Are identified as requiring occasional or infrequent irrigation in Borstein, et al., or Plants and Landscapes for Summer Dry Climates (EBMUD). Are identified as requiring no summer w ater in EBMUD. Are identified as requiring little or no w ater in the Sunset Western Garden Book. Are identified as requiring low or very low irrigation in the Guide to Estimateing Irrigation Water Needs of Landscape Plantings in California (University of California Cooperative Extension). Plants not listed in any of the above references w ill require that the design professional base selection upon successful experience w ith species on previous projects under similar horticultural conditions. Site-specific Factors. Given Alameda County spans several Sunset climate zones, w ith variable humidity, heat, frost, and w ind factors, as w ell as varying soil characteristics, plants need to be selected w ith an understanding of specific climate and microclimate conditions, and grouped in appropriate hydrozones. Supplemental watering needs. Many plants listed as drought tolerant per the above references may require more supplemental w atering in fast-draining, engineered soils. B-2 APPENDIX B C.3 STORMWATER TECHNICAL GUIDANCE B.3 Plants for Stormwater Measures Plants play an important role in the function of landscape-based stormw ater treatment measures: . Infiltration and evapotranspiration. Plants aid in the reduction of stormw ater runoff by both increasing infiltration, and by returning w ater to the atmosphere through evapotranspiration. Sedimentation. Some stormw ater treatment measures, such as vegetated sw ales and vegetated buffer strips, are designed to remove coarse solids through sedimentation that is aided by dense, low -grow ing vegetation. Pollutant trapping. Vegetation helps to prevent the resuspension of pollutants associated w ith sediment particles. It is essential that pollutants removed during small storms are not remobilized during large storms. Phytoremediation. Plants for stormw ater treatment measures are important for their role in phytoremediation, the uptake of nutrients and the ability to neutralize pollutants. Soil stabilization. As in any landscaped area, established plantings help control soil erosion. This is important both to keep sediment out of stormw ater and to retain the surface soils, w hich help to remove pollutants from infiltrated runoff. Aesthetic benefits. Plants w ithin or adjacent to stormw ater facilities provide an aesthetic benefit. Plants suitable for use in stormw ater treatment measures are organized according to the follow ing categories: . Emergent refers to those species w hich occur on saturated soils or on soils covered w ith w ater for most of the grow ing season. The foliage of emergent aquatics is partly or entirely borne above the w ater surface. Grasses refer to those species that are monocotyledonous plants w ith slender-leaved herbage found in the in the Family Poaceae. Herbaceous refers to those species w ith soft upper grow th rather than w oody grow th. Some species w ill die back to the roots at the end of the grow ing season and grow again at the start of the next season. Annuals, biennials and perennials may be herbaceous. Shrub is a horticultural distinction that refers to those species of w oody plants w hich are distinguished from trees by their multiple stems and low er height. A large number of plants can be either shrubs or trees, depending on the grow ing conditions they experience. Tree refers to those species of w oody plants w ith one main trunk and a rather distinct and elevated head. APPENDIX B B-3 ALAMEDA COUNTYWIDE CLEAN WATER PROGRAM Plants suitable for use in stormw ater treatment measures are listed in tw o w ays. First, a comprehensive list of all recommended plant species is provided in Table B-1, w hich lists the plants in alphabetical order by Latin name, in the categories described above. The columns in Table B-1 indicate stormw ater treatment measures for w hich each plant species may be suitable. Follow ing Table B-1 are brief descriptions of the stormw ater measures for w hich technical guidance is included in this handbook, including the suitable plantings from Table B-1. Invasive species. Under no circumstances shall any plants listed as invasive under www.cal- ipc.org/paf be specified. B-4 APPENDIX B CLEAN WATER PROGRAM ALAMEDA COUNTY Table B-1 Plant List for Stormwater Measures Emergent Species Artemisia douglasiana Carex barbarae Carex densa Carex obnupta Eleocharis macrostachya Hydrocotyle ranunculoides Juncus balitcus ¹ Juncus bufonius Juncus effusus ¹ Juncus leseurii Juncus mexicanus Juncus patens Juncus xiphioides Limonium californicum Phragmites spp. Scirpus actutus Scirpus americanus ¹ Scirpus californicus ¹ Spartina foliosa mugwort Grass Species Typha angustifolia Santa Barbara sedge Typha latifolia dense sedge slough sedge Agrostis exarata creeping spikerush Alopecurus aequalis marsh pennywort Alopecurus saccatus baltic rush Aristida purpurea toad rush Carex pansa Pacific rush Carex praegracilus common rush Carex divulsa (tumulicola) Mexican rush Chondropetalum tectorum blue rush Danthonia californica iris-leaved rush Bioretention Area - including Deschampsia cespitosa ¹ Marsh rosemary linear treatment measure Deschampsia cespitosa ssp. holciformis common reeds Deschampsia danthonioides tule Distichlis spicata three square Eleocharis palustris california bulrush Flow-Through Planters Elymus glaucus California cordgrass Festuca californica narrowleaf cattail 2 Tree Well Filters Festuca idahoensis cattail Festuca rubra¹ Festuca rubra 'molate' spike bentgrass Vegetated Buffer Strip Hordeum brachyantherum ¹ shortawn foxtail Leymus triticoides Pacific foxtail Purple three-awn Infiltration Trench Linum usitatissimum ¹ Grass Species cont'dLolium perenne ¹ California meadow sedge Melica californica clustered field sedge Extended Detention Basin - Berkeley sedge Melica imperfecta cape rush biotreatment soil California oatgrass Muhlenbergia rigens tufted hairgrass Pacific hairgrass Extended Detention Basin - annual hairgrass non-biotreatment soil salt grass creeping spikerush * Denotes riparian species with limited drought tolerance blue wild rye Turf Block Pavers ¹ Denotes species with phytoremediation capabilities 2 California fescue Non-tree species to be used only with adequate planting surface and when infiltration rates are 5-10 inches/hour Idaho fescue red fescue Green Roof - extensive Molate fescue meadow barley creeping wildrye Green Roof - intensive flax ryegrass California Native California melic coast range melic Drought Tolerant^ deergrass CLEAN WATER PROGRAM ALAMEDA