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Where Land and Water Meet The Rich Interconnections of Floodplain Forests Robert J Naiman Professor Emeritus School of Aquatic & Fishery Sciences Within Our Reach Conference 8 December 2016 Photo: Wallick et al. 2013 Significant Ecological Features of Rivers and Floodplains The ecological vitality of natural streams, rivers and floodplains – and the First Foods derived from them – is largely determined by the flow regimes of water, sediment and organic matter Floodplains are valuable “hotspots” for sustaining individual species, biodiversity, and water quality – largely due to their inherent ecological structures and processes Nearly all floodplains in the Pacific Northwest – regardless of type and location – have been significantly altered by human actions A Brief Ontogeny of Scientific Discovery The discovery phase challenges and refines perspectives of how rivers and their floodplains function as ecosystems • • • • • • • Columbia River Food Web River ecosystem patterns from headwaters to the sea (Vannote et al. 1980) Effects of large dams and reservoirs on river corridors (Ward and Stanford 1983) Hyporheic zones (Stanford and Ward 1988, Boulton et al. 1998) Roles of large animals in shaping stream dynamics (Naiman 1988, Naiman et al. 2002) Importance of floods (Junk et al. 1989, Poff et al. 2010), seasonal flows (Bunn and Arthington 2002), riparian zones (Décamps 1996, Naiman and Décamps 1997), and habitat mosaics (Stanford et al. 2005) Spatial dynamics of species and populations adapt and prosper in changing habitats (Fausch et al. 2002) And many, many others • Basically, we learned that rivers and their floodplains are highly complex and resilient ecological systems Basic Ecological Processes Underpin Floodplain Productivity, Biodiversity and Natural Resilience 1. River-specific flow patterns 2. Productivity is ‘fuelled’ by locally generated carbon & nutrients mixed with carbon & nutrients from the catchment 3. Seasonal movements of biota facilitated by flood regimes 4. Productivity – and food webs – sustained by hydrological connectivity 5. Fire is a major consumer of carbon and key in the redistribution of nutrients and wood 6. River-floodplains have inherent resilience to natural variability but only limited resilience to artificial modifications (Pettit et al. 2016) Questions for Exploration Stories of Discovery How does dynamic complexity (in space and time) influence basic ecological characteristics of rivers & floodplains? Why are floodplains so productive in the face of constant physical change? Where does the food come from to support the productive animal communities (fish, amphibians, birds)? Do species matter? Dynamic Complexity and Floodplain Characteristics Rio Negro, Brazil Channel Meandering – Queets River, WA 1962 1996 1939-2002 Floodplains are Physically Complex Source: Wallick et al. 2013 Floodplain Biodiversity - Plants Pollock et al. 1998 Productivity in the Face of Constant Physical Change Despite constant change (“disturbance”) and nutrient leaching, floodplain trees often exhibit exceptional growth rates and long lives How is this accomplished? Successional processes Biogeochemical mechanisms Biotic considerations (epiphytes) Successional Processes Van Pelt et al. 2006 Biogeochemical Mechanisms H2O + CO2 from root metabolism and from decomposition of organic matter = Carbonic acid Carbonic acid + fine sediments deposited from floods = abundant micronutrients Despite massive rainfall there is highly efficient retention of K (potassium), Ca, Mg – but not N or P Is the widespread focus on N + P in ecology misplaced? Additional nutrient processes are mediated by tree epiphytes and mosses, abundant adventitious roots on limbs, and capture of micronutrients in marine aerosols Floodplain Epiphytes Van Pelt & Naiman, unpublished Biogeochemical Mechanisms H2O + CO2 from roots and from decomposition of organic matter = Carbonic acid. Carbonic acid + fine sediments deposited from floods = abundant micronutrients Despite massive rainfall there is highly efficient retention of K (potassium), Ca, Mg but not N or P. Is the widespread focus on N + P in ecology misplaced? Additional nutrient processes mediated by tree epiphytes and mosses, abundant adventitious roots on limbs, and capture of marine aerosol micronutrients. Is the popular focus on the need for marine-derived nutrients misplaced? What has been lost by the widespread cutting of mature floodplain forests? Understanding the biogeochemical basis for floodplain productivity is paramount in appreciating their formidable ecological qualities Where Does the Food Come From? We remain highly uncertain as to where and how sufficient quantities of food are produced, and precisely at the right times Surprises from bioenergetics modeling and experiments Organic matter budgets: Role of floodplain hyporheic zones in food production Bioenergetics Modeling and Experiments Food demand: spring-summer Chinook salmon smolts Lower Granite Dam to Bonneville, 461 km ~9 million hatchery and wild yearling Chinook, May 2008 ~13 day migration Total food required: 166.5 MT 33.3 MT dipterans 52.1 MT other insects 38.8 MT Daphnia 42.2 MT amphipods Source: Transect of Riverine Aquatic Habitat by California Trout Importance of Floodplain Hyporheic Zones Fluxes in the hyporheic zone Flathead River, MT Moisie River, Quebec Do Species Matter? Yes – and the biochemical aspects are vitally important BEARS PRESENT Terrestrial herbivores Terrestrial scavengers High-quality browse BEARS EXTIRPATED Terrestrial herbivores Lower-quality browse Plentiful marine nutrients Partially eaten carcasses Little marine nutrients Few carcasses Slower-growing spruce trees Fast-growing spruce trees Small-bodied scavengers Bears Large wood Retention sites High carcass retention Less large wood Fewer retention sites Fewer carcasses Less spawning habitat Spawning habitat Fry Productive rearing habitat Fewer fry Abundant spawners Smolts Diminished rearing habitat Fewer spawners Fewer smolts Adult salmon Fewer adult salmon Final Thoughts The resilience and productivity of floodplains are truly remarkable, especially in light of the constant natural changes imposed upon them They are full of ecological surprises and, while much is known, much remains to be discovered – especially on the frontiers of chemistry and genetics “Sure kid, you start out working for the ecosystem but pretty soon you figure out how to get the ecosystem to work for you!” A Vision for Riverine Floodplains It is time to move beyond isolated management and restoration actions to Basin-scale strategies. Strategies with broadly integrated actions based on a landscape perspective – one that seamlessly links social and ecological considerations Thank You! Implementing such a perspective with its attendant philosophies, ethics and visions is just as important for local sustainable economies and cultures as it is for individual species, biodiversity, and healthy floodplains Photo: Wallick et al. 2013 END THE ONTOGENY OF RIVER-FLOODPLAIN CONSERVATION AND RESTORATION PHASE 1 - DISCOVERY Exploration and understanding of patterns and processes PHASE 2 - CONSERVATION Protecting species and places PHASE 3 - RESTORATION Re-establishing environmental functions and conditions Integrating conservation and restoration processes with social drivers and expectations 1970 1980 1990 PHASE 4 - 2000 EFFECTIVE ACTIONS 2010 Naiman 2013 Key Challenges for Integrated Floodplain Management in the Willamette Basin • Re-establish adequate fluxes of bedload, suspended sediments and large wood onto floodplains These are the building material for floodplains, most is trapped by dams or prevented from entering channels. Floodplains are not physically stable – they change dramatically in response to floods as well as to regulated flows Operationally, this means allowing streams and rivers to periodically overtop banks and fill floodplains. Flood and bankfull stages (as determined by the US Weather Service) often seek to help prevent overbank flows Key Challenges for Integrated Floodplain Management in the Willamette Basin • Establish a healthy perspective between urban areas and flooding. This is central to having an integrated floodplain management strategy Rethink the design of cities, businesses, and farms to accommodate periodic flooding – (e.g., 2-yr inundation is critical for aquatic communities, provides important food resources and many functions without greatly impacting adjoining land use, and represents areas most easily altered by channelization, riprap, and levees) Resistant?; certainly not resilient Key Challenges for Integrated Floodplain Management in the Willamette Basin • Overcome complex social issues (e.g., landowners, public perceptions and values), technical hurdles (e.g., engineering complexity, loss assessment, appropriate M&E) and effective coordination (seamless integration among agencies, Tribes, land owners and project sponsors) At the Basin scale, think and act in creative ways, improve adaptive capacity as individuals and as communities, and empower stewardship and the assumption of personal responsibility