Biodiversity Guide - The Intertwine

egional conservation strategybiodiversity guideChapter 3 Major Habitat Types of the Regionmining and recreational uses (e.g., rock climbing).One such site is Madrone Wall, formerlyknown as the Hardscrabble Quarry, located inClackamas County southeast of Carver. Nestingperegrine falcons were discovered on theMadrone Park site in 2010. A large unprotectedexample of rock habitats is situated above St.Helens, Oregon.Bretz Flood FeaturesThe Tonquin Geologic Area comprises approximately17 square miles of land in Washingtonand Clackamas counties, extending from thecommunities of Tualatin and Sherwood south toWilsonville. The area supports extensive evidenceof the Bretz (or Missoula) Floods that scouredthe Columbia River Gorge and extended intothe Willamette Valley multiple times betweenapproximately 13,000 and 15,000 years ago. Thesefloods left behind geologic formations such askolk ponds and channels, basalt hummocks, andknolls, which are widely present in the area todayand which support considerable and diverseplant, fish, and wildlife habitat.Springs and SeepsSprings and seeps are places where groundwateremerges, sometimes under pressure, with variabletemperature and chemistry. Water from springsand seeps usually flows into a local wetland orforms the headwaters of streams and rivers.Springs and seeps provide cold water to wetlandsand streams, making them particularly importantto native fish and invertebrates that needcool water to thrive. Several rare and decliningamphibian species, such as torrent salamandersand the coastal tailed frog, are closely associatedwith springs, seeps, and headwater habitats. Somesprings are important sources of minerals that areneeded by wildlife, including band-tailed pigeons.Many springs have been tapped for domesticwater supplies or farm and ranch uses. At suchsites, water typically has been piped or divertedand sometimes is polluted. The wetlands createdby springs and seeps may be altered or degraded.Vernal PoolsVernal pools are one of Oregon’s rarest wetlandtypes. They form on impervious basalt bedrockor on soils cemented by a calcareous or siliceoushardpan that impedes drainage. Pools can rangein size from 1 acre (0.4 hectare) or more topatches as small as 10 to 225 square feet (1 to 5square meters) and can occur singly or in groupscovering many acres. Vernal pools usually fillwith water in the fall or winter and dry up inspring or early summer, but seasonal precipitationcan be highly variable, so pools may fill foronly brief periods or not at all. They are home toa large variety of plants and animals adapted tothese harsh conditions, including some globallyrare species. Vernal pools are threatened primarilyby urbanization on the typically flat and easilyaccessible landforms in which they occur. Vernalpools are important habitats for amphibians,rare plants, and fairy shrimp and other invertebrates.(For more on vernal pools, see “Wetlands,”above.)FensFens are a unique type of wetland that includesa shallow lake with a floating peat mat. Fensare habitat for unique and rare plants as well asa variety of declining wildlife species, such asamphibians and turtles. It takes up to 10,000 yearsfor a fen to form naturally. The only known fenleft in the Willamette Valley was recently protectedby Metro. (For more on fens, see “Wetlands,”above.)Off-Channel HabitatsOff-channel habitat features such as beaverponds, oxbows, stable backwater sloughs, andside channels are important ecological componentsof river systems, especially large systemssuch as the Columbia and Willamette rivers andtheir major tributaries. Many species and ageclasses of native fish select off-channel habitatinstead of the main channel to feed, avoidpredation by other fish, escape fast water, or seekout cool water in the summer. Native turtlesand amphibians, birds, freshwater mussels, anddragonflies are attracted to alcoves, oxbows, andside channels because of unique physical andwater quality characteristics. In the last 150 years,off-channel habitats have disappeared becauseof channelization, revetments, diking, drainageof wetlands, removal of large wood, agriculturalpractices, and changes in seasonal flows thathave resulted from the construction of damsthroughout the Willamette and Columbia basins.Off-channel habitats now are uncommon in theregion, especially in the lower reaches of the WillametteRiver. (For more on the importance ofthese habitats to fish, see Chapter 5.)Conservation Strategies and OpportunitiesA priority strategy for managing and restoringspecial habitat features is to protect and maintainthose features that remain on the landscape.Because not all remnant SHF are known andmapped, land use policies should be in place toprotect them once their locations are known. Insome cases, special habitat features should bebuffered from activities on adjacent lands becausethe features themselves typically are vulnerable todegradation; buffering also is needed because themany species of flora and fauna associated withspecial habitat features tend to be sensitive tohuman-caused disturbances.The following conservation strategies also arerecommended:n Control invasive species.n Restore natural flow regimes and re-createoff-channel habitats.n Manage beaver populations to provide forbeaver-created off-channel habitats.n Provide buffers for springs and seeps.n Enforce seasonal closures to protect sensitivewildlife (e.g., birds nesting on cliffs).n Site recreational trails away from special habitatfeatures.n Employ forest management practices to createand maintain forest openings.n When addressinghazard trees, leave asection standing (highstumpmethod) toprovide some wildlifebenefit; leave woodonsite in large pieces asmuch as possible.n Retain existing snagsand downed woodwhere they occur; managefor future snags anddowned wood by girdlingor topping trees.n Evaluate methods to imitate natural vernalpool function in old ditches and depressions inagricultural fields.n Improve mapping of all special habitat features.For More InformationOregon State Conservation Strategyhttp://www.dfw.state.or.us/conservationstrategy/read_the_strategy.aspWashington State Comprehensive Wildlife ConservationStrategyhttp://wdfw.wa.gov/conservation/cwcs/cwcs.htmlSnags: The Wildlife TreeWashington Department of Fish and Wildlife.http://wdfw.wa.gov/living/snags/Oregon Wetlands Explorer: Major Wetland Typeshttp://oregonexplorer.info/wetlands/DiversityandClassification/WetlandTypesInformational Guide: Streams, Springs and SeepsCity of Portland Oregon, Bureau of DevelopmentServices, Land Division. http://www.portlandonline.com/bds/index.cfm?a=72543&c=45482Draft Recovery Plan for Vernal Pool Ecosystems inCalifornia and OregonU.S. Fish and Wildlife Service. http://www.fws.gov/pacific/ecoservices/endangered/recovery/vernal_pool/6061