The Role of Abandoned Channels as Refugia for Sustaining Pioneer Riparian Forest Ecosystems

摘要: In disturbance-prone ecosystems, organisms often persist in spatial refugia during stressful periods. A clear example is the colonization of abandoned river channels by pioneer riparian trees. Here, we examine prominence this establishment pathway for a foundation tree species (Fremont cottonwood, Populus fremontii) within corridor large river, Sacramento River central California. We quantified total proportion forest that initiated as result channel abandonment 160-km reach, analyzed concurrent patterns with floodplain accretion and sedimentation history, developed conceptual model biogeomorphic evolution channels. Historical air photo analysis indicated stands associated comprised more than 50% extant cottonwood area. Tree-ring evidence showed commonly immediately following abandonment, recruitment window ranged from 4 to 40 years, but was less 10 years at most sites. Rates rise fine sediment accumulation were high young sites decreased logarithmically over time. Together, these results suggest are an important refuge recruitment, greatest opportunity occurs short period after cutoff event, processes influence duration window. On rivers where along active severely limited hydrologic regulation and/or land management, may play even role sustaining ecologically functional corridor. Preserving bank erosion, meander corridors regeneration zones created events therefore key conservation measures on shifting rivers.