Download Where Land and Water Meet The Rich

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
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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