Presenter/s: Katrina Strathmann
Symposium Session: 2024 - 11 Restoring Habitat for Overlooked Aquatic Organisms
Topics covered: cottonwoods
ABSTRACT
Cottonwood forests are a foundational species in lowland alluvial floodplain and channel systems in the arid west. Cottonwood forest provide shade, floodplain roughness, food-web nutrient input, and a source of large wood critical to maintaining channel morphology and in-channel habitat complexity for anadromous fish, including salmon, steelhead, and lamprey. On the Yakima River, land use activities have eliminated riparian forests, levees and roads have restricted the river’s migration zone where riparian forests are created, and river regulation attenuates annual flood patterns that are required for cottonwood establishment. Supportive flow conditions for cottonwood recruitment are naturally restrictive, and cottonwood recruitment under unregulated flow conditions occurs at intervals typically resulting in a riparian forest mosaic of many single-aged stands. Lack of riparian forest regeneration on regulated rivers has been identified as a key problem in stream systems throughout the west. Without successful recruitment, cottonwood stands will die out as older trees senesce without replacement. The presentation will report results of assessments of cottonwood regeneration in Yakima River basin, and outline strategies to improve cottonwood recruitment and survival and to restore cottonwood forests.