Quiz 1 - Setting the Stage Flashcards
Why are we now seeing the need for ecological restoration? (4)
Rapid population increases (especially since the 1950s)
Lowest sockeye salmon run on record this year
Summer 2019 was a tipping point (Amazon deforestation, Greenland ice sheer broke)
Rapid increase in CO2 concentration
What did Jean-Baptiste Alphonse Karr write one 1848?
“The more things change, the more they are the same.”
How has our thoughts about climate change changed over the last 10 years?
Climate denial to climate acceptance to climate emergency (House of Commons May 1st 2019)
When was the dam era and how did our views on dams change? (2)
In the mid-late 1960s, it was believed that water running to the ocean was wasted and that it should be harvested in dams
This lasted until people began to see the effects on fish: eg. Bruce Babbitt (Secretary of the Interior) under the Clinton Administration who wrote a book about America’s Evolving Views of Dams
What are some of the impacts of this Dam Era? (5)
Fish spawning runs destroyed
Downstream rivers altered by changes in temperature
Unnatural nutrient load and seasonal flows
Wedges of sediment piling up behind structures
Delta wetlands degraded by lack of fresh water and salt water intrusion
What did the UN General Assembly fo recently? (2)
Declared 2021-2030 the UN Decade on Ecosystem Restoration on April 8th, 2019
Aims to scale up the restoration of degraded and destroyed ecosystems as a proven measure to fight the climate crisis, enhance food security, water supply, and biodiversity
The effects of poor forest harvesting on stream/river ecology and salmonid habitat (8)
- Altered drainage patterns
- Hill slope failures from logging road construction
- Siltation
- Loss of LWD
- Channelization
- Loss of fish passage at road crossings
- Oligotrophication
- Thermal stress from lack of vegetation and increased solar radiation
When did people realize that forestry was affecting steam ecology?
In 1885 when Van Cleef states that cutting down trees and bank damage affected salmonids and their habitat
However, back then they didn’t know what to do about it
The start of industrial logging (3)
Industrial logging has been occurring for over 120 years
The environmental damage caused by hand logging was limited by the amount of energy (people/strength) thar was available to cut and remove trees from the forest
Stream engines then diesel and gas turbine engines greatly increased the damage because it increased the available energy exponentially
Altered drainage patterns (2)
Drainage patterns were affected by the straightening of channels, leaving large wood in channels, compaction etc.
This led to erosion and greater sediment delivery to streams which changed the stream itself (positive feedback loop)
Increased slope failures (3)
Caused by building cheap logging roads to reach higher slopes (“end hauling” was safer but more expensive)
Old roads failed from “overloaded side casts” that frequently incorporated decaying logging debris
These failures then caused issues on the downhill slope
Why do logging roads and hill slopes fail? (4)
Altered drainage patterns
Loss of vegetation cover/evapotranspiration
Overloaded side cast fill
Increased rainfall intensity associated with climate change
Increased siltation
Logging can cause siltation in salmonid habitat including the infilling of pools, riffles, spawning gravels etc.
Loss of LWD inputs (4)
Historically, most streams were logged to the banks (until 1988 on the coast)
This creates a legacy of bank erosion and a major deficit in the supply of large mature trees to stream channels
Resulting in a loss of LWD in channels at about 10% per decade
50-100 years post-logging, streams and rivers in the PNW are still low in LWD
What is the main reason why LWD is important to salmonids? (2)
LWD is the primary structuring element for juvenile fish habitat for summer rearing and overwintering
Large trees play a dominant role in forming pools, metering sediment, trapping spawning travels, and creating a more complex stream environment
What trees are best suited as LWD? (3)
Cedars are best as they may not decay for centuries
Fir and spruce trees can last for decades
Alder and cottonwood rot within a few years
What are the consequences of decreased amounts of large wood? (3)
Loss of cover and structural complexity
Decreased availability and abundance of habitat units
Reduced varieties of current velocities and other hydraulic features
I.e. the habitat is simplified
Importance of LWD for young salmonids (4)
Large trees and root masses can provide slow back water areas during high flows and floods
Prevents young of the year coho and smaller steelhead juveniles from being swept downstream
Salmonid juveniles that are displaced from smaller streams when under their optimal size survive poorly in larger river environments
Biologists have documented substantial decreases in over-wintering coho salmon in streams after clear cut logging in riparian zones
How long until BC’s rivers return to large supplies of large wood entering by natural processes?
75-150 years
What are the main natural processes of LWD inputs? (4)
Wind throw
Bank erosion
Tree decay
Tributary debris flow
Channelization (2)
Common where streaks were aligned or diverted to protect logging roads, crossings, log sorting areas and mulling sites
Results in loss of channel and fish habitat complexity (simplification)
Fish passage (4)
Adult fish passage at logging road culverts has been a long standing concern
Many culverts are impassible to juveniles, which often require off-channel refuges to successfully overwinter
Large areas of watershed can be blocked simply due to debris or weirs
Easy, cheap fix to remove or replace perched culverts
Oligotrophication
Subtle consequence of combined effects of forest harvesting habitat degradation and commercial overfishing (removing wood and salmon reduces nutrient input)
Thermal stress (2)
Caused by increased solar radiation and a lack of riparian vegetation
Temperatures over 24*C are lethal to all salmonids
Loss of riparian areas results in: (9)
Increase in sediment and siltation
Increase in solar radiation and stream temperature
Increase in evaporation and runoff resulting in less water in summer/fall and more in winter
Loss of riparian leaf litter inputs
Excessive nutrient loading = algal blooms and loss of stream invertebrates
Increase in turbidity
Loss of LWD input
Increased loading of vet pharmaceuticals and pathogens into watercourse (agriculture)
Increase in taste and odious for downstream water use (agriculture)
How does overgrazing affect the water table? (2)
Reduces riparian vegetation which increases runoff and evaporation so that the water table isn’t replenished
This leads to a lower water table and the drying out of steams in summer
How does land use effect the soil? (2)
Causes increased erosion and physical loss of soil
How can we restore agricultural land use impacts on streams? (3)
Stream fencing
Livestock water access stations
Riparian planting
Effects of urbanization on salmonid habitat and stream ecology (2)
Creation of impervious surfaces
Removal of vegetation allowing contaminated rainwater to flow overland and into streams, rivers, and lakes as point and non-point spice pollution
Urbanization and pollution (3)
Up until the 1980s, sewer systems combine sewer and storm water into one pipe which leads to Combined Sewer Overflows (CSOs) during heavy rains
Now the drainage systems are separated (but some old ones still remain)
Storm water contains oil, grease, gas, diesel, brake fluid, transmission fluid, antifreeze, brake and clutch dust, tire rubber etc.
How do we combat polluted storm water draining into waterways?
Infiltration galleries, created wetlands, detention ponds, swales etc. are all designed to intercept overland and storm drain flows and allow the water to deep slowly back into the ground or into water courses
Specific dates important for logging in riparian areas (4)
1962 - scientists (D.W. Chapman) began getting first hand knowledge of the effects of logging on fish, but there wasn’t much research on it
In B.C., all streams were logged to their banks until the inception of the Fish Forest Clear Cut Guidelines in 1988 and the Forest Practices Code in 1995
1985 - end of an era for logging companies to work unregulated (conflict arose over one coastal logging road (sustainable resource use, old-growth forests and First Nations rights on Lyell Island)
How does size generally relate to stability for large woody debris?
In general, the large the LWD, the most stable in the stream channel as heavier flows require higher flows for mobilization and longer pieces are more likely to be caught by the stream bank and its vegetation
What does the condition of the riparian zone dictate? (2)
The condition of the riparian zone can make the stream more susceptible to logging related impacts and can determine the ability of the stream to recover from such impacts
Effects of sedimentation on fish and fish habitat (5)
Increases in sediment input can reduce stream habitat complexity, thereby reducing fish species and macroinvertebrate composition and population abundance
Sedimentation and reduction in inter and inter-gravel water flow can harm eggs (reduce oxygen or smother), reduce habitat for alevin, juvenile fish, and other organisms, directly kill or harm fish
Reduces water clarity and visibility which impairs the ability of aquatic life to find food, mate, and escape predators
Lead to the elimination of critical food items such as insects and aquatic invertebrates
Fish death can depend on whether the turbidity issue is acute or chronic (eg. Low turbidity for long periods of time can result in death just as a short period of high turbidity)
Logging practices and sedimentation (2)
Logging practices affect steam channel morphology by altering the amount of sediment and water input to stream channels
Excessive inputs of coarse sediment via landslides and erosion deposit in pools, thereby reducing critical pool habitat for overwinter and summer cover
Effects of logging on stream hydrology (7)
In general, studies indicate that stream flow increases once a certain threshold of forest cover has been removed
Most studies have been done on the West Coast, in either OR or BC
In one study in OR, in the HJ Andrews Experimental Forest, the removal of 30% of vegetation from a forested watershed caused a 12-28% increase in minimum streamflow
Another study concluded that clear cut logging increased the size of peak flows in rain on snow runoff processes
In a neighbouring watershed, 80% deforestation caused an 85% increase in minimum stream flows
The highest clear cutting resulted in the highest maximum stream flows
The removal of trees (and transpiration) provided a soil mass which was more moist and responsive to precipitation events
Rain on snow events (3)
Rainstorms thar result in large amounts of surface runoff due to the combined effects of heavy rainfall and snowmelt
Rapid snowmelt is caused by 1.heat supplied from the warm air that is characteristic of intense rainstorms and 2.by heat released during condensation of moisture from the air onto the snow surface
Can cause significant damage to streams as rain falls on frozen ground may cause flooding and heavy erosion
What are the requirements for a rain on snow event to be considered? (2)
Events must have at least 0.33mm of rain falling on a minimum of 1cm of snow already on the ground
Trace amounts of snow on ground or rainfall occurring on a day were not included in analyses in the prairies and northern provinces of Canada
What physical processes cause heat transfer from the atmosphere and terrestrial environments to a stream after logging? (6)
Snowfall accumulations Net solar radiation Evaporation Convection Conduction Advection
What is the primary driver of temperature in unshaded coastal streams?
The input of solar radiation is much more important than the air temperature or the cooling effect of evaporation in controlling stream temperature
The ecological effects of increased temperature are: (4)
Complex
Site specific
Species specific
Not always negative
Riparian treatments of Carnation Creek (6)
- Leave-strip butter: 1-70m wide from the estuary to 1300m upstream
- Intensive clear-cutting: along 900m upstream (took all trees off-site/out of stream)
- Careful clear-cutting: 900m upstream (left shrubs but took trees)
Study conducted over 3 phases:
- Pre-harvest: 1970-1975
- During harvest: 1976-1981 when about 41% id watershed was harvested
- Post-harvest: currently from 1982 to 2006 when about 21% more of the basin was logged in headwater areas
Main structural effects of forest harvesting in Carnation Creek study (5)
Bank erosion causing the channel to become wider and more shallow
Loss of large woody material and the accumulation of woody debris into recently formed logjams
Movement of sand and pea-sized gravel to the lower reaches of the stream and estuary
Post logging widening of the channel, accelerated scour and deposition, and loss of stable LWD have been largely due to stream moving around these logjams and sediment deposits and redistributing materials downstream
Short term and long term habitat changes has affected all salmonids in the watershed
Main temperature effects of forest harvesting in Carnation Creek study (4)
Riparian clear cutting increased stream temperatures in all seasons
Mean monthly temperatures in small, lofted tributaries have increased by as much as 4*C in summer
Mean temperatures in main creek have increased by as much as 3.2C in August, 0.7C in December, and 2*C in April
Increases during autumn and winter were relatively small but had the most profound effects on salmonid populations
Uses of Carnation Creek study (5)
Results have been widely used to develop forest management practices, regulations, and guidelines in B.C. and elsewhere in the PNW
BC Coastal Fisheries Forestry Guidelines (CFFG) which were first implemented in 1987 and guided forestry practices in coastal forest districts until 1994, were based primarily upon research information from Carnation Creek and the Queen Charlotte Islands
It subsequently made substantial contributions toward the development of the hill slope, stream, and riparian management provisions of the Forest Practices Code id BC which replaced the CFFG in 1995
The FPC was applied to the entire province and contained legally binding regulations together with guidelines and recommended best management practices
These provisions remain as default environmental standards under the new Forest and Range Practiced Act
