20-year Forest Restoration Plan - City of Kirkland

20-Year Forest Restoration PlanWhy Kirkland’s Forested NaturalAreas are DecliningFive basic problems prevent the city’s forested natural areas fromsustaining themselves as native habitat:1.2.3.4.5.FragmentationDeclining canopyInvasive-dominated understoryNative species struggle to regenerateInadequate funding for natural area management/restorationFragmentationKirkland’s forested natural areas are widely dispersed throughoutthe city due to development. Many are isolated and lackconnectivity to other natural areas. Fragmentation often resultsin habitat degradation and loss. It poses significant challengesto the diversity of native plants and wildlife species that use severalhabitat types throughout their life stages. Fragmentationalso increases the exposure of forested natural areas to humanimpacts, pollution, and invasive species.Declining CanopySeveral factors contribute to the loss of Kirkland’s forest canopyin parks and open spaces. Deciduous trees make up a disproportionateshare of the forest canopy. Based on an assessmentof Kirkland’s forested natural areas by International Forestry,pioneering alder and big-leaf maples nearing the end of theirlifespan now comprise more than 90% of Kirkland’s natural areaforest canopy.The high proportion of mature deciduous trees in the canopywill continue to rapidly decline. Most over-mature deciduoustrees are either dead or dying, allowing sunlight to reach theground surface. Because most invasive species are more aggressivein full sun, the loss of canopy has allowed invasive plants tobecome the dominant species in many areas of Kirkland’s forestednatural areas.Removal of vegetation along many riparian areas includingstreams, wetlands, and their buffers has resulted in a completeloss of native species cover. Many streams are now buried undera canopy of invasive species such as blackberry, ivy, or reedcanary grass. Loss of native vegetation along our aquatic habitatsresults in significant impacts on stream temperatures andwater quality that influence aquatic species such as salmon.Invasive-Dominated UnderstoryIn the understory, invasive plants now out-compete nativeNorthwest plants. Invasive species cover the ground and blocknative species from sprouting. Especially alarming is Englishivy. English ivy, through a combination of root and leaf competitionand sheer mass, can kill deciduous trees within 20years. Ivy and morning glory look green and harmless, but theyquickly spread from an understory blanket into the tree canopies,covering leaves and blocking photosynthesis. Their weightalone is enough, over time, to break branches and stunt growth.Meanwhile, blackberries and Scot’s broom work in the understoryto crowd out ferns and other native species.Currently, invasive plant growth outpaces the stewardshipavailable to control it. Without intervention, the result is slowlydying forested natural areas with little or no chance of returningto a native ecosystem.English ivy destroys trees through sheer mass and competition for sunlight.19