wetlands: biodiversity offsets: challenges and considerations
DESCRIPTION
Written by Dave Howerter, Director of Conservation Science, Ducks Unlimited CanadaTRANSCRIPT
Wetlands: ecology of prairie wetlands and their importance to waterfowl
Wetlands: Biodiversity Offsets: Challenges and considerations David Howerter & Karla Guyn, Ducks Unlimited Canada
Outline Wetland definition Wetland Classification Wetland Values Offset Challenges DUC Experiences Atlantic Canada Alberta
“ …. land that is saturated with water long enough to promote wetland or aquatic processes as indicated by poorly drained soils, hydrophytic vegetation, and various kinds of biological activity which are adapted to the wet environment.”
(Wetlands of Canada, 1988, page 416)
What is a wetland?
• there are five classes of wetlands in the Canadian Wetland Classification System: bogs, fens, swamps, marshes, & shallow water wetlands
Canada’s Wetlands
• organic wetlands (> 40 cm of peat): - bogs - fens
peatlands
Canada’s Wetlands
Bogs
peat-covered wetland
wetland isolated from ground water
low nutrients
water and peat usually acidic
dominated by Sphagnum mosses with tree, shrub or treeless vegetation cover
Bogs
Fens
peat-covered wetland
wetland exposed to groundwater
more nutrients than bogs
less acidic
greater variety of plants than bogs: grass meadows, shrubs, and trees
Fens
• organic wetlands (> 40 cm of peat): - bogs - fens
peatlands
• mineral wetlands: - swamps - marshes - shallow open water
Canada’s Wetlands
Swamps
non-peat forming wetland
waterlogged soil, often with standing water
vegetation is dense coniferous or deciduous trees, or tall shrub thickets
water-loving plants
Swamps
Marshes
Marshes
non-peat forming wetland
waterlogged soil in plant rooting zone, often with standing water
nutrient rich water offering greater plant diversity: emergent reeds, rushes or sedges
surface water level may fluctuate seasonally
Shallow open waters
Shallow open waters
non-peat forming wetlands locally known as ponds or sloughs standing water, often a transition between
lake and marsh fewer emergent plants but submersed plants
may be present water depth usually < 2 meters
Canada has approx. 127 million ha of wetlands (24% of all the world’s wetlands)
Prairie Pothole Region
Manitoba
Montana North Dakota
South Dakota
Iowa
Minnesota
approximately 715,000 km2
Stewart and Kantrud (1971)
based on vegetative growth
allows for a more detailed classification
Stewart, R. E. and H. A. Kantrud. 1971. Classification of Natural Ponds and Lakes in the Glaciated Prairie Region. Resource Publication 92, Bureau of Sport Fisheries and Wildlife, U.S. Fish and Wildlife
Permanent Ponds (Class V)
Semi-permanent Ponds (Class IV)
Seasonal Ponds (Class III)
Temporary Ponds (Class II)
Ephemeral Ponds
(Class 1)
Wetland Area = 10 Ha
One 10 Ha wetland = 1 Mallard Pair
Source: Reynolds, R.E., D.R. Cohan, and M.A. Johnson. 1996. Using landscape information approaches to increase duck recruitment in the Prairie Pothole Region. Trans. N. Amer. Wildl. And Nat. Resour. Conf.
Relationship Between # Mallard Pairs/Ha of Wetland and Individual Wetland Size (in Ha)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6
Wetland Size (in Ha)
Mal
lard
Pai
rs/H
a
Wetland Area = 10 Ha
Ten 1 Ha wetlands = 3 Mallard Pairs
Wetland Area = 10 Ha
One Hundred 0.1 Ha wetlands = 9 Mallard Pairs
Wetland Offset Challenges 1. Equivalency
– Variability – Clear Objectives, Agreement on Currency
Wetland Values Water Quality Nutrients Chemicals Sediments
Water quantity Flood prevention Groundwater recharge
GHG sequestration Recreation Biodiversity
Hydrologic Response To Draining Wetlands
current drainage area boundary
wetlands
stream
Hydrologic Response To Draining Wetlands
Hydrologic Response To Draining Wetlands
New drainage area boundary
Wetland Offset Challenges 1. Equivalency
– Variability – Clear Objectives, Agreement on currency
2. Proximity – Benefits accrue at different scales
Wetland Restoration vs. Securement
A) Fall 2008 B) Spring 2009 C) Fall 2011
Wetland Offset Challenges 1. Equivalency
– Variability – Clear Objectives, Agreement on currency
2. Proximity – Benefits accrue at different scales
3. Timing – Benefits accrue at different rates
4. Additionality – Expected rates of loss
Offset rules
cabaysdirt works.com
Wetland Offset Challenges 1. Equivalency
– Variability – Clear Objectives, Agreement on currency
2. Proximity – Benefits accrue at different scales
3. Timing – Benefits accrue at different rates
4. Additionality – Expected rates of loss
5. Equitability
Wetland Offset Challenges 1. Equivalency
– Variability – Clear Objectives, Agreement on currency
2. Proximity – Benefits accrue at different scales
3. Timing – Benefits accrue at different rates
4. Additionality – Expected rates of loss
5. Equitability 6. Lack of wetland inventory/monitoring
Atlantic Province Offset Similarities NB, NS and PEI: Wetland and Watercourse Alteration
Regulation Mitigation Sequence in place Ratios established NB 2:1, NS 2:1, PE 3:1
Alberta Offset rules Mitigation Sequence in place Variable Ratios Within same watershed
Wetland Offset Challenges 1. Equivalency
– Variability – Clear Objectives, Agreement on currency
2. Proximity – Benefits accrue at different scales
3. Timing – Benefits accrue at different rates
4. Additionality – Expected rates of loss
5. Equitability 6. Lack of wetland inventory/monitoring 7. Finding a qualified delivery agent!
Delivery Agent
Identify suitable projects Manage and maintain projects as required Provide long-term security Monitor projects Provide effective and efficient process
Ducks Unlimited Canada, a private, non-profit charitable organization, conserves, restores and manages wetlands and associated habitat for North America’s waterfowl. These habitats also benefit other wildlife and people.