Silverweed. Potentilla Anseri.

How to propagate Silverweed.

220px-Zilverschoon_plant_Potentilla_anserinasilverweed potentilla anserina

More info: http://www.wildflower.org/plants/result.php?id_plant=ARAN7

Native use in BC: Hull’s Field in Langford. http://www.cityfarmer.org/nativecrops.html

USA. Plant Profiles. http://plants.usda.gov/java/profile?symbol=ARAN7&photoID=poan5_001_ahp.tif

Protocol Information for Silverweed

Mark E. Majerus                                  USDA NRCS – Bridger Plant Materials Center                  99 South River Road, Rte. 2, Box 1189                  Bridger, Montana 59014-9718                  (406) 662-3579                  (406) 662-3428                  mmajerus@mt.nrcs.usda.gov                  http://plant-materials.nrcs.usda.gov/mtpmc

Family Scientific Name: Rosaceae
Family Common Name: Rose
Scientific Name: Argentina anserina 
Common Name: Silverweed cinquefoil
Species Code: ARAN7
Ecotype: See
General Distribution: Alaska to southern California, mostly eastern Cascades, east to Atlantic, and in Eurasia; meadows and moist banks.
Propagation Goal: Seeds
Propagation Method: Seed
Product Type: Propagules (seeds, cuttings, poles, etc.)
Target Specifications: Harvest yields vary due to weather and age of stand. Average annual  production is 46 kg/ha (41 lb/ac).
Propagule Collection: Wildland collection occurs early August to mid September when  the yellow flower has turned brown and the achene is wrinkled and corky; difficult to hand-harvest because of prostrate, stoloniferous form.One collection hour/person will yield an average 34 grams (1.2 oz) clean seed (ranged 27 to 40 grams and varies by year, stand density, and collector experience).
Propagule Processing: Seed Processing: Seed is spread out on a tarp in a dry, sheltered environment and turned daily for approximately 3-5 days, until no moisture or warmth is detected. Seed is threshed with a hammermill through a 4/64” round hole screen, air-screen processed on an Office Clipper over a 1-20” round hole screen with very low wind. Due to tiny seed, absence of seed debris, and moderate seed flow, this species is moderately easy to clean. Larger seed lots are processed most efficiently with mechanized cleaning equipment and smaller seed lots usually require more hand labor. Seeds/Kg: 2,900,000. Purity 100%.
Pre-Planting Treatments: Seed Treatments: None required.
Growing Area Preparation/ Annual Practices for Perennial Crops: Propagation Environment:Seedbed is firm and free of weeds with good field moisture to 4” depth. Seed Propagation Method: Direct seeding.
Establishment Phase: Sowing Date: Spring. Sowing/Planting Technique: 25-30 pure live seed/ft. (0.3 m) row, irrigated 91cm (36 in) row spacing, seeded with 2-row double-disk planter with depth bands, optimum seeding depth 0.6 cm (0.25 in). Establishment Phase: Soil surface is kept moist throughout the 14 day germination and emergence period (also helps prevent soil crusting).Fertilizer application is not recommended the first year, as it generally stimulates weed growth and competition.
Length of Establishment Phase: 2 growing seasons.
Active Growth Phase: Rapid Growth Phase: Spring to fall; soil moisture is critical during budding stage, after anthesis, and post harvest to pre-freezeup –no irrigation is applied during flowering (pollination); fertilizer is broadcast at 100 lbs actual N/40 lbs actual P/acre in mid-September.
Length of Active Growth Phase: 2 to 3 growing seasons.
Hardening Phase: N/A.
Harvesting, Storage and Shipping: Harvest Date:) Cultivated harvest occurs late June to late July, with a mean harvest date of July 12 at the Bridger Plant Materials Center.Hand-harvesting is required because the seedheads are  low to the ground.Seed Storage:Seed is placed in plastic ziplock bags (seed is so small it may sneak out of paper containers), repeatedly punctured to prevent moisture buildup, placed in cloth or plastic seed sacks, and stored in a cool, dry environment. Seed Dormancy: Classified as physiological dormancy.
Length of Storage: Storage Duration: 5 to 7 years.
Outplanting performance on typical sites: Outplanting Sites: Dunraven Pass to Canyon and  Fishing Bridge to Lake Butte. Northeast Entrance.
Other Comments: Ecotype: 2 different Yellowstone National Park accessions periodically collected and produced from 1986 to 1990. Grassland ecological zones include Idaho fescue/bearded wheatgrass and  silver sagebrush/Idaho fescue habitats. Elevation 2,438 m to 2,682 m (8,000 ft to  8,800 ft).
References: Flora of the Pacific Northwest, C. L. Hitchcock and A. Cronquist, University of Washington Press, 1973.Yellowstone Vegetation – Consequences of Environment and History in a Natural Setting, Don G. Despain, Roberts Rinehart Publishers, 1990.Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination, C. C.  Baskin and J. M. Baskin, Academic Press, 2001.
Citation:
Winslow, Susan R.  2002.  Propagation protocol for production of   Argentina anserina seeds; USDA NRCS – Bridger Plant Materials Center, Bridger, Montana.  In:  Native Plant Network.  URL: http://www.nativeplantnetwork.org (accessed 15 June 2013). Moscow (ID): University of Idaho, College of Natural Resources, Forest Research Nursery.

PEAT and PARKS

Technically, the area where Cadboro Bay Gyro Park sits is known as a wetland fen. A fen is composed of water and decayed plant material primarily from various kinds of sedges and reeds.

1008_butterfly121-300x200

A fen takes thousands of years to develop and is characterized by a water table that is fed by ground water, fluctuates during the year, is rarely totally dry and is rarely totally flooded.

The Cadboro Bay Fen contains (very approximately) 3 million to 7 million cubic feet of peat. It was “topped up” around 1954 by about 500,000 cubic feet of bark chips and sawdust from the Victoria wood mills.

The area was once home to many kinds of fish and molluscs and there was an estuary where Todd Creek entered the ocean. Salmon came up Bowker Creek to spawn in the region where Bowker and Todd connected and the fry returned to the ocean via Todd Creek and the estuary.

The nature of a fen makes the kinds of development common to parks difficult and expensive. Peat is very useful as a carbon store and is quite fertile, but it is compressible. A living fen constantly renews itself. An exposed fen oxidizes and release carbon dioxide. A fen covered in hog fuel and grass acts unpredictably. If a fen is drained it can be farmed, but then it begins to subside and needs to be drained yet again or allowed to retain to its natural state.

At the moment, while speaking in a Green fashion of restoring wetlands, Saanich in these plans is treating this area as though it were entirely composed of the normal classes of soil (silt, sand, clay and humus) and therefore could be managed as those kinds of soil are: paved, moved, excavated, built-upon, forested, bermed, swaled and grassed. The municipality is also using peat’s capacity to absorb water as part of its arsenal to deal with the surface water common to the rain forest environment of Vancouver Island during the winter months. These two functional goals are at cross purposes.

One major requirement of Park users is to have the park dry enough to be used year round. All three variations of the current plan assume that this will happen and that raised asphalt paths can be built to provide wheel chair access and parking can be improved/created such that it is maintenance free and playgrounds can be “raised” to be useful year round. However, residents have not been provided with the hydrogeological studies which would explain how this all would happen.

There are some fundamental and unanswered questions.

    1. How much peat is there?
    2. What is its condition?
    3. How much ground water flows into this body of peat during the winter months?
    4. What is the annual growth rate of that winter ground water flow given proposed development of the village centre and surrounding area?
    5. What are the targets for the level of ground water in the park at various times of the year?
    6. For how many months will the ground water be at or above the surface level.
    7. Where will the large pumps be that will manage the water table? How much will they cost?

In many places in these plans, the word “raised” is used, whether for paths, parking, buildings or playgrounds. But how will this take place? If the load has a SG > 1, it will sink into the original surface of the fen. Example: the “raised” pathway and rock wall near the octopus from earlier renovations. These have subsided as one would expect for heavy objects imposed on a peat-based wetland.

Consultation on future planning for improvements to this park requires answers to all the fundamental questions raised above.

An active Fen with the harvest of sedge hay.

SedgeCutting

Harvested Sedge Hay in Part of the Cadboro Bay Fen in 1941

UCC farm pic--tweaked

 

Fen Restoration. Planting Process.

fens near ely--warercolour-with cattleThere are various ways to restore wetlands of various kinds.
This watercolour is of a fen near Ely, England. With cattle. Note how low the open water is.
large sedge-aquascapes.carex_oshimensis_evergold   www.plant-pictures.net
What follows is a restoration methodology from a nursery in Muncie, Indiana which outlines the stages and the different levels with different sets of plants. Note how waterfowl need to be kept away from the new plants for a year.

Specifications for Installation of Wetland Plants in Stormwater Wetlands (According to Marion County, Indiana Regulations)

Part 1 General

A.        Preparation
B.        Seeding
C.        Planting
D.        Seed Protection
E.         Waterfowl exclusion
F.         Maintenance

1.02 Bidder qualifications

A.        The submitting bidders shall be, and have been, actively and directly engaged in wetland plant installation for a period of two (2) or more years. Provide proof of five (5) or more successful wetland plant installations.
B.        Qualified bidders shall possess specialized equipment for working in and around water, including a small boat, hip waders, and floatation life preservers to be worn while working in water.

1.03     Environmental Requirements

A.        Installation shall be performed during the growing season, specifically between March 15th and September 30th.
B.        Hydrology shall be established prior to installation. Wetland must have an established water level.
C.        Surrounding uplands shall be stabilized with the specified grass seed mix. No pre-emergent herbicides shall be applied to surrounding turf during the six months prior to installation and for at least 1 year following installation.
D.        Emergent plants shall be installed prior to seeded communities.

1.04     Materials

A.        All native seed shall be stored in a cooler at 40 degrees Fahrenheit prior to installation

1.         All native seed must be of wild ecotype as provided by Spence Restoration Nursery or approved local source. No hybrids or cultivars may be included.
2.         Local genotype seed shall be used whenever possible due to its adaptation to local soil and climate. These specifications do not apply to the temporary matrix.

B.        Container grown plants shall be used for the emergent plant communities.

1.         Container grown plants must be of wild ecotype as provided by Spence Restoration Nursery in 2 3/8”X 3 ¾” open bottomed pots. No hybrids or cultivars may be included.
2.         Container grown plants shall be inoculated with pelletized VAM (Vesicular Arbuscular Mycorrhizae) endomycorrhizal fungi as provided by Spence Restoration Nursery or approved source where available.

Part II – Products

2.01 Plants
A.        Low Marsh 6-18 inches

Installation must include at least three of the species below, including two aggressive species marked with an asterisk(*). Species noted by the number sign (#) may be installed bare-root. Others must be installed from container grown plants.

Pickerel Weed (Pontederia cordata)#

Stormwater Wetlands 3

Hard-Stemmed Bulrush (Scirpus acutus)
River Bulrush (Scirpus fluviatilis)#*
Soft-Stem Bulrush (Scirpus validus)*
Giant Burreed (Sparganium eurycarpum)*

B. High Marsh: 6 inches or less below normal pool elevations.

Installation must include at least 6 of the species below, including two aggressive species marked with an asterisk(*).

Sweet Flag (Acorus calamus)
Water Plantain (Alisma subcordatum)
Bristly Sedge (Carex comosa)
LakeSedge (Carex lacustris)*
Tussock Sedge (Carex stricta)
Hairy-Fruited Lake Sedge (Carex trichocarpa)*
Buttonbush (Cephalanthus occidentalis)
Creeping Spike Rush (Eleocharis erythropoda)*
Swamp Rose Mallow (Hibiscus palustris)
Soft Rush (Juncus effusus)
Wild Iris (Iris versicolor)
Blue Flag (Iris virginica shrevei)
Rice Cut Grass (Leersia oryzoides)*
Arrowhead (Sagittaria latifolia)*
Lizard’s Tail (Saururus cernuus)
Dark Green Bulrush (Scirpus atrovirens)
Woolgrass (Scirpus cyperinus)
Three-Square Bulrush (Scirpus pungens)*

 

C.        Semi-Wet Zone – Areas above normal pool that are occasionally inundated

Installation must include container grown plants or a seed mix containing at least 15 species below including two aggressive species marked with an asterisk (*). Species appropriate for shady locations are marked with a carrot (^)

Marsh Milkweed (Asclepias incarnata)
Shining Aster (Aster firmus)
New England Aster (Aster novae-angliae)
Swamp Aster (Aster puniceus)
Flat-Topped Aster (Aster umbellatus)
Tall Brome (Bromus latiglumis)^
Blue-Joint Grass (Calamagrostis canadensis)*
Marsh Marigold (Caltha palustris)^
Brome Hummock Sedge (Carex bromoides)^
Fringed Sedge (Carex crinita)^

Stormwater Wetlands 4

Crested Sedge (Carex cristatella)
Riverbank Tussock Sedge (Carex emoryi)*
Frank’s Sedge (Carex frankii)^
Meadow Sedge (Carex granularis)^
Burr Sedge (Carex grayi)^
Porcupine Sedge (Carex hystericina)
Bottlebrush Sedge (Carex lurida)
Palm Sedge (Carex muskingumensis)^
Spreading Oval Sedge (Carex normalis)^
Short’s Sedge (Carex shortiana)
Narrow-Leaf Cattail Sedge (Carex squarrosa)^
Awl-Fruited Sedge (Carex stipata)^
Pointed Oval Sedge (Carex tribuloides)
Fox Sedge (Carex vulpinoidea )
White Turtlehead (Chelone glabra)^
Pink Turtlehead (Chelone obliqua)^
Hollow Joe-Pye Weed (Eupatorium fistulosum)
Spotted Joe-Pye Weed (Eupatorium maculatum)
Boneset (Eupatorium perfoliatum)
Queen of the Prairie (Filipendula rubra)
Fowl Manna Grass (Glyceria striata)^
Autumn Sneezeweed (Helenium autumnale)
Torrey’s Rush (Juncus torreyi)*
Cardinal Flower (Lobelia cardinalis)^
Great Blue Lobelia (Lobelia siphilitica)^
Common Mint (Mentha arvensis)
Monkey Flower (Mimulus ringens)
Obedient Plant (Physostegia virginiana)
Golden Ragwort (Senecio aureus)^
Ohio Goldenrod (Solidago ohiensis)
Swamp Goldenrod (Solidago patula)
Riddell’s Goldenrod (Solidago riddellii)
Prairie Cord Grass (Spartina pectinata)
Tall Ironweed (Vernonia altissima)
Smooth Ironweed (Vernonia fasciculata)

2.02 Accessories

A.        Waterfowl Exclusion

1.         Posts – 6 foot lightweight fence posts

2.         Fence – 4 foot width of plastic filaments with 1 inch square openings.

B.        Potting mix – Sterile dry potting mix composed of a light-weight vermiculite mix

Stormwater Wetlands 5

 

Part III Execution

3.01 Examination

A.        Verify that a stable water level has been established in the wetland.

B.        Verify that the surrounding uplands have been stabilized with the specified

grass seed mix.

3.02 Preparation

A.        Two weeks (14 days) prior to installation, apply a glyphosate herbicide approved for use around water (Rodeo) to the area to kill existing vegetation.

B.        Following a complete kill of existing vegetation, begin installation by tilling any areas to be seeded to a depth of 3 inches. Till as close to the shoreline as soil moisture conditions permit. Do not till areas where live plants are to be installed.

3.03 Installation of waterfowl exclusion fence

A.        Place posts on 15 ft centers. Each post shall be driven approximately 1 foot into the pond bottom. Install fence to form 15′ X 15′ enclosures. Form each enclosure immediately following installation of plants. Planted areas shall not remain unprotected overnight.

B.        Attach fence to posts with wire ties so that the fence extends to the pond bottom and at least 30 inches above the waters surface.

3.04 Installation of Plants

A.        All aquatic plants must be installed in the appropriate water depths where protected by waterfowl exclusion fence and the shore. 50% of the 15’X 15′ enclosures shall be planted according to the specifications below.

1.         Low marsh plants shall be installed 6-18 inches below normal pool elevation. Install plants on 2′ centers. Evenly distribute each species around the pond, planting in groups of 3 to 5 plants of each species.

2.         High marsh species shall be installed 6 inches or less below the normal pool elevation. Install plants on 18″ centers. Evenly distribute each species around the pond, planting in groups of 3 to 5 plants of each species.

3.         Semi-Wet zone species shall be installed in areas above normal pool elevation that are inundated by larger storm events. These species shall be Stormwater Wetlands 6

installed as either container grown plants on 12″ centers or an approved seed mix containing species from the above list.

B.        All low and high marsh plants shall be installed by creating a hole with a spade or dibble, placing the plants in the hole and firmly packing the soil around them. Plants allowed to float to the surface following installation shall result in rejection

of the installation.

C.        Plants installed in the semi- wet zone shall be installed by creating a hole with a gas powered hand-held auger.

1.         Holes shall be created in a staggered pattern on 1 foot centers.

2.         Plant plugs level with existing soil grade. Be certain that soil is placed around the plugs and firmed into place. Do not fill around plugs with mulch.

3.         Thoroughly soak plugged area with water until soil is moist to a depth of 4 inches.

3.05 Seeding

A. Place a portion of the seed in a clean, dry 5 gallon bucket. Mix 2 parts potting mix with 1 part seed. Thoroughly mix seed and potting mix.

B. Hand broadcast potting mix/seed mixture across the specified tilled area. Apply half of the mixture over the entire area. Apply the second half over the same area utilizing the same procedure. This method prevents using all of the seed before the entire area is covered.

C. Lightly firm seedbed with a roller where soil moisture permits. Do not roll areas where soil is moist enough to stick to the roller.

3.06. Protection

A. Protect seeded areas with stakes and tape around area periphery.

3.07. Maintenance

A. Pull weeds of the following invasive species deemed detrimental to wetland

plantings.

Purple Loosestrife (Lythrum salicaria)
Common Reed (Phragmites australis)

Stormwater Wetlands 7

Cattails (Typha spp)

B. Remove unwanted woody seedlings in shoreline areas including Cottonwood (Populus deltoides), Willow (Salix spp), and Silver Maple (Acer saccharinum).

C. If weed growth exceeds ten inches in height in seeded areas, trim or mow to 4 inches. Do not cut areas where live plants were installed.

D. Maintain waterfowl exclusion fence for 1 year. At the end of that period, remove fence and posts.

3.08 Acceptance

A. Planted Wetland Communities – For acceptance at the end of the first growing season, the following condition shall be met for areas where live plants were installed.

1.         75% of the species planted shall be alive and present.
2.         50 % of the water surface in the shallow water community shall be covered with vegetation.
3.         25 % of the water surface in the floating leaf community shall be covered with vegetation.

B. Seeded Native Communities – For acceptance at the beginning of the second growing season, the following conditions shall be met.

1.         Coverage – 80 % of each plant community shall be covered with/by Vegetation.
2.         Presence – 50 % of the species planted should be alive and present.
3.         Abundance – 50 % of the vegetation should native species of the permanent matrix.

Fen Plant Images

http://www.bing.com/images/search?q=Sedge+Plant&FORM=RESTAB#view=detail&id=5B77F30A8699DF2FAE7148A581F8838249CEFDCC&selectedIndex=176

A more detailed management guide is here:

http://www.bohnsfarm.com/_ccLib/attachments/pages/LANDSCAPE+GUIDE+for+Stormwater+BMP+Design_1008.pdf

This one has an excellent chart of plants. St. Louis, USA, zoned.

Wetland in a Wetland

Discussions are underway to modify the 15 acre Cadboro-Gyro Park so that it includes a wetland.

The purposes of the proposed wetland are noble.  The fact sheet asks for a wetland that will:

  • increase habitat,
  • facilitate new recreational and educational opportunities,
  • contribute significantly to the park’s ecological integrity and
  • mitigate extended flooding within the park.

The park has been the subject of several reviews in the past, most of which were triggered by concerns
related to flooding, underground service lines, and maintenance. It is noted that development and maintenance of the park is extremely challenging due to::

  • unstable peat soils,
  • a high water table, and
  • stormwater and tidal influences.

What is ironic about all of this is that the entire park is actually a wetland already and that some state of  “flooding” is normal for the entire area most of the year.

Cadboro-Gyro Park was developed in a fen alongside an ocean. Fens are peatlands. Peats  are very, very stable–unless you try to put a highway or train track  over them. And guess what?

Fens are characterized by:

  • peat soils,
  • a high water table,
  • stormwater and tidal influences.

Fens are one of the four main kinds of wetlands. They are characterized by being fed by mineral-rich surface water or groundwater and by the fact that over time they develop beds of peat which help absorb and disperse the groundwater which in turn supports the specific kinds of plants which, very slowly, form the peat. Fens are different from marsh wetlands in that they are shallower and that the fauna develops on or near the surface. They are distinguished from bogs in that bogs are fed solely by rain and are thus acidic whereas fens are neutral or alkali. When drained in whole or in part, fens make very good farmland.

The following activities are not normal in fens or are difficult to accomplish: roads, paved areas, railroads, buildings, parking lots, golf courses, playgrounds, grassy parks. Any of these detract from “the ecological integrity” of the park.

Natural fens are very useful for: mitigating the effects of storms and heavy rainfalls, providing a home for diverse fauna and wildlife, the growing of sedges, reeds and osiers for commercial purposes, cleaning up contaminated water, storing carbon.

The natural purpose of this fen for many years was to receive the surplus water from three or four hundred acres on higher ground to the north west.  The fen wetland before HBC and farm settlements would have been much larger in 1850 and it was farmed quite successfully until housing and shops began to expand in the f1950’s.

For centuries, this “surplus” water would have nourished the plants covering the tens of acres of fens which ran parallel to the shore. Given that much of that original fen is now built up and that the farms of the uplands have been covered with houses and roads and parking lots, the ratio between  the land receiving groundwater and the land drained has decreased enormously: let us say (without any detailed calculation) from 1 to 6 down to 1 to 60. Except for the 15 acres of the park, all of the original fen is now covered in houses and roads.

Logically, since all 15 acres of park are actually a wetland now, the park design should be quite different than is now proposed. This is not Beacon Hill. This  is a peatland/wetland and what lies under the surface is as much a part of that wetland as the water that often floods the planted grass as nature tries to move things back to their more natural state.

Sand and beach.

The beach is a natural dividing land and should serve its original purposes as summer recreation for the people and a winter dog-walking haven. It should be celebrated and made as accessible as possible for individuals. It should be expanded where feasible as each small bay or indentation increases the available space for summer recreation.

Parking.

Parking for cars should be eliminated or moved to the older parts of the fen, along Cadboro Bay Road. One house has been bought and two or three more could be purchased contiguous to the Cadboro Bay Road entrance. Walking is healthy.

Boats.

Boat storage could remain as a buffer between the existing housing and the park. So this buffer area might well take up two or three acres in whole but the goal should be to minimize the built/paved area and maximize the wetland.

Playgrounds.

The play area should remain where it as, as that terrain is almost part of the sandy beach terrain. Or, it could move or expand to the buffer area. The scout house is on a lease so must stay where it is for the time. When it goes, that would be a good site for washrooms.

Washrooms.

Washrooms have been solidly established and in any case the part of the wetland where they sit has been damage has been damaged. So they might as well stay rather than damaging another location.

Paving.

No area should be “paved”  as currently planned. That would be very expensive and detract from “ecological integrity.” To pave over peat you need to bring in tons of sand, let it sit there for a year or two until the peat compresses, take away the sand, and then pave. For the same amount of money, you could restore ten acres of fen.

Peat.

The existing peat beds should be mapped in detail and restoration goals should be set for their health and development. Appropriate wetland species should be planted over at least 8 acres of the existing part which would be more than enough area to properly establish a fen wetland with some substantial “ecological integrity”. We need to start adding to the peat again.

Trees.

No trees should be planted and existing trees should be removed where they are invasive and contribute to peat degradation. The invasion of trees marks the end of the wetland character of any particular wetland except a swamp and the types of trees which grow in swamp wetlands are not particularly attractive. While trees are considered “green” in all cases, in fact they do not contribute at all to the ecological integrity of a wetland.

Waterflow.

In the past, there very likely was a marsh wetland portion or portions of the fen between the main fen and the ocean. If a true wetland is created, there should be a number of ponds and waterways within the vegetation. The general flow of water from outside the fen should be into the fen from outside, through the fen, and eventually, as clean water, into the ocean. This entails somewhere, towards the middle of the beach, a fen-marsh-ocean transition area.

Access.

Access to the beach should be mainly by foot or bicycle. There should be a large area for bicycle storage near the foot of Sinclair. There is an extensive literature about walkways through fens in Holland, England, Scotland and elsewhere.

Fundamentals:

Almost all of the planned developments lessen the “ecological integrity” of these 15 acres. These 15 acres represent the last segment of a major fen/marsh wetland that lasted for tens of centuries and that covered at least 150 acres.  We can seize the moment and create a true wetland  or we can pave and grass over most of this land and build a pseudo-wetland with a plastic liner in one corner of the park, first of all excavating all the peat.

This is a radical proposal in the circumstances but it is the logical outcome of an emphasis on ecological integrity and the management of “surplus” water.

lowtide-Cadboro-Bay-2-2011-07-30-Cadboro-Bay-Beach-view

FENS. Part 1.

hay sedge planthay sedge

My interest in fens is growing. I am restructuring my posts on this subject. Dave Godfrey

1.  General Introduction

Fen: a fen  is a type of wetland, a broad expanse of nutrient-rich, ground-fed  shallow water in which dead plants do not fully decay, resulting in a flora of emergent plants growing in saturated peat. The other 3 types of wetlands are bogs, swamps, and marshes.

Simply put: swamps and marshes have lots of water, salt or fresh. Swamps have trees. Bogs and fens have saturated soil. The water in a bog comes from rain water. The water in a fen comes from ground water and/or flowing water. Fens are rich in nutrients and can be grazed in perpetuity if proper managed.

Wicken-Fen-Hide-meadow

Good video introductions to Fens

Wildlife: http://www.youtube.com/watch?v=mdFeQaSeDl4

General: http://www.youtube.com/watch?v=5cxmYYReNe8

Cycling the fen: http://www.youtube.com/watch?v=cmEocg3OW1I  Turn the volume down.

Dung digging: http://www.youtube.com/watch?v=XRsSGwCojBA  Why grazing is good for fens.

Wild bees at Wicken: http://www.youtube.com/watch?v=445FH_RqWDs

Wicken Windmill in song: http://www.youtube.com/watch?v=EpUxFH3RfhI

2. Wetlands in General

{habitat_image_alt}CAREXoshimensis
Wetlands form over any land whose soil is either seasonally or permanently waterlogged. This can happen alongside rivers, across floodplains, where there are springs and seepage, a high water table or tidal incursion.

Water-logging tends to exclude oxygen from the soil and plants have evolved many ways to deal with this, leading to the evolution of hundreds of specialist wetland and waterside species.

Wetland habitats include marshes, fens, bogs, water-meadows and any muddy place by water; they  often include systems of aquatic habitats such as ditches, rills and streams which can also be important for plants. Wetland complexes in the UK such as the Broads, Somerset and Pevensey Levels, form extensive networks of habitats which are rich in many other forms of wildlife. Canada has an extremely diverse set of wetlands in all parts of the country. Holland and the UK lead in Fen restoration.

3. Wetland Habitat features

1, Bogs

Upland and Lowland bogs are characterised by the dominance of Sphagnum moss species, which lay down layers of bog peat as they grow. Sphagnum acidifies its own environs and so bog systems are populated with plants that can cope with base-poor, acid waters. In England, upland blanket-bogs cover more than 10,000 hectares of land and are hugely significant in the landscape.

2. Fens and reedbeds

This kind of habitat occurs in river valleys and floodplains that are not conducive to the development of Sphagnum dominated vegetation. Sedges and rushes tend to dominate and common reed is a prominent species, although its abundance is greatly affected by management; fens and reedbeds have a very long history of traditional management, some being grazed but many cut for ‘fen litter’ or ‘marsh-hay’, a product that went for feed and bedding for the many thousands of horses that once populated our towns and cities. Fen-litter and saw-sedge, another traditional fen product, are both cut in late summer, which suppresses reed growth; however winter cutting encourages reed growth and leads to such dominance that the reed can be harvested in bulk for thatching.

3. Wet woodland

Mature wet woodland is a rarity, as opposed to swampy woodlands, and isoften restricted to the margins of fens and marshes and the fringes of slow moving rivers. Typically dominated by alder or willow, it can be a species-rich habitat, especially where it occurs at one end of a complete transition from open water to woodland.

4. Water meadows and wet grasslands

Although often badly affected by agricultural improvement, these grasslands can form extensive systems in river valleys and the lower parts of river floodplains. Associated with traditional extensive grazing regimes, where intervening ditches are maintained as ‘wet-fences’, such grassland networks form some of the most intact wetland systems.

5. Farmable wetlands.

UCC farm pic

Some wetlands, in some seasons, can be quite productive. It has been estimated that the full value of wetlands in terms of annual benefits is in the order ten to fifteen thousand dollars a hectare. The Cadboro Bay fen was used mainly for pasturing and  the production of sedge-hay also termed meadow hay.

SedgeCutting

4. Transition

Wetlands may be seen as transitional stages moving from open water towards woodland. The technical term hydrosere is used to describe a succession which starts in water. A wetland is a transitional area between open water and dry land and may contain several stages of a hydrosere at the same time. Some studies add a fifth type: shallow open water.

In time, an area of open freshwater such as a lake or marshy sea shore may become woodland. During this process, a range of different habitats such as marshes and fens may succeed each other. Peat usually accumulates slowly, at the rate of about a millimetre per year.

This succession from open water to climax woodland is likely to take at least several thousand years although some intermediate stages will last a shorter time than others. For instance, a shallow swamp may change to marsh within a decade or less. How long it takes will depend largely on the amount of siltation occurring and whether storms and tides scour out established vegetation from time to time.

If there are five or six feet of peat beneath Gyro Park, one can be sure that it has been a long time since the area was a marsh. However, the calculation is complex since after the last Ice Age, the island rose but so did the sea levels.

5. Key issues

Perhaps the single most influential factor in the loss of wetlands is drainage. Wetland soils, particularly fen peats, make fine agricultural soils if the water can be got rid of. This has of course already happened across many tens of thousands of hectares of former wetland habitat, with unfortunate consequences in terms of soil loss through oxygenation and shrinkage, windblow and carbon release.

The flower-richness of wetland habitats is dependent also on good water quality. Where wetlands are fed by rivers which pass through towns and cities and intensively farmed agricultural areas, high nutrient concentrations in the water cause a few species to outgrow the majority, leading to a rapid decline in floral diversity.

Abstraction of water from underground sources can reduce supplies of water to spring fed systems. . This leads to a gradual drying out, loss of water-dependent species and ultimately to complete loss of the wetland habitat. Water-levels can often be restored quite quickly, with the withdrawal of abstraction, but this does not necessarily lead to a restoration of former vegetation, mainly due to the oxygenation and breakdown of formerly water-logged soils.

Changes in agriculture and the way people live their lives has led to a decline (and in some cases almost complete loss) in markets for traditional fen produce. This has led to fens becoming uneconomic to manage in the traditional way, leading to conversion to agriculture or abandonment.

Recently, however, analysis of methods of carbon storage have revitalized interest in the peat bogs which cover 3%  of the earth’s surface and store an estimated 550Gt of carbon. Drainage of peatlands leads to mineralisation of carbon and nitrogen from the peat, releasing the greenhouse gases CO2 and N2O to the atmosphere and thus contributing significantly to global warming. It is estimated that such land use induced changes are responsible for 6 % of anthropic CO2 emissions, with well-known hotspots in south-east Asia (SEA) and central and eastern Europe (CEE). It is also well known that rewetting of drained peatlands can increase carbon storage.

The International Mire Conservation Group produces a reputable (and free) journal covering wetlands world wide. Here is a review from that journal of the carbon credits and peatland restoration question. http://www.mires-and-peat.net/map11/map_11_br_03.pdf

6. LIST OF FEN PLANTS

Yellow Flag

220px-Iris_pseudacorus_001

In pools

In typical fen

In fen carr

General article on sedge: carex: http://en.wikipedia.org/wiki/Carex

7. Canadian Expertise.

Canada has a large percent of the world’s peatlands.

Despite continued detrimental impact to wetlands, Canada still has over 127 million hectares of wetland comprising
an estimated 24% of the total world wetland base.

For a long time, Canada was a leader in wetland research, but this expertise is now in decline. One great book from the golden era is this one:

http://www.gret-perg.ulaval.ca/fileadmin/fichiers/fichiersGRET/pdf/Doc_generale/Wetlands.pdf

8. Bluedale

To get an idea of plants you can grow for your own wetland, check out this great (Australian) site on Facebook.

https://www.facebook.com/pages/Bluedale-Wholesale-Nursery/149284481811934

Westringa video:

http://www.youtube.com/watch?v=SbR7op5u2gc&list=UUqoGgTBQ7tfyg5FdvPL2N6g

Juncus usitatus

juncus usitatus at bluedale

Or this one in California: sedge plants available:

http://www.smgrowers.com/search/bsearchcarex.asp?strSearchText=carex

List of grasses and sedges in the Fraser Valley:

http://www.natureguidesbc.com/files/Grasses.pdf

9. British Columbia

Environment BC has done some good work on wetlands, but again, in the past decade, this seems to have fizzled. The following excerpts are from a useful document: http://www.env.gov.bc.ca/wld/documents/WEG_Oct2002_s.pdf

Although British Columbia has large areas of natural wetlands, the situation in urbanized areas is critical.

Wetlands are one of the most important life support systems on earth. Currently comprising about 5.6% or 5.28 million hectares of British Columbia, they provide critical habitat for fish, birds, and other wildlife. Most wildlife in the province use wetland habitat at some point in their life cycle, and many red- and blue-listed species are wetland-dependent.

Creston Wetlandslowtide-Cadboro-Bay-2-2011-07-30-Cadboro-Bay-Beach-view
The functional contribution of wetlands in helping to minimize or remediate environmental problems is substantial. They absorb and filter sediments, pollutants, and excess nutrients; recharge groundwater; maintain stream flows; control runoff; store flood waters; reduce erosion; stabilize shorelines; and help regulate atmospheric gases and climate cycles. In short, wetlands absorb water quickly and release it slowly with an improvement in quality.

Wetlands provide for commercial and recreational use of wetland-dependent fish and shellfish, enhance agricultural productivity, and support a variety of scientific , educational and recreational opportunities. Environmental economists such as Robert Costanza have used various methods to estimate the economic market and non-market values of the goods and services of various ecosystems. For wetlands, the total value is estimated to be $19,580 hectare/year (1994 US$). Using this figure to estimate the goods and services value of wetlands, British Columbia’s total wetland surface area of 5.28 million hectares would yield a potential value of over $100 billion/year. At a local level such as the Fraser Valley, the total wetland surface area of 41,906 hectares would yield a potential goods and services value to society of over $800 million/year.

There is a growing concern over the escalating rate of wetland losses in British Columbia. In the Fraser Vancouver Island, it is estimated that 50% to 70% of the original wetland habitat has disappeared. In the ecologically critical South Okanagan, wetland losses have reached 85%.

Action is required to help reduce wetland losses and provide for coordinated conservation and management efforts. Because wetlands occur across a range of ecosystem types and can be affected by various land use activities, a comprehensive approach is needed to ensure the protection and management of wetlands. It is intended that several initiatives currently under development, including the Biodiversity Strategy, Species At Risk Strategy, the Living Rivers Strategy, as well as ongoing Land Use Planning and Protected Areas management, will all play an important role in protecting, maintaining and restoring wetlands.

10. Capital Region District

Another good summary. http://www.crd.bc.ca/watersheds/ecosystems/wetlands.htm

Map of watersheds: http://www.crd.bc.ca/watersheds/publications/documents/GreaterVictoriaWatersheds.pdf

11. Local

Mystic vale and Hobbs Creek.

There were once salmon here. A great detailed study is here: http://www.urbanecology.ca/documents/Student%20Technical%20Series/Oliver%20hannah%20final.pdf

A local report from 2005: http://www.islandnet.com/~thelynns/cbra/minutes/cbramin_2011_01_10_mystic_pond.pdf

Another summary of what could/should be down with Mystic Vale and Hobbs Creek: http://web.uvic.ca/enweb/undergraduate/pdf/MysticVale.11.09.pdf

Another group doing interesting work on communities: http://mapping.uvic.ca/welcome/committee

Some other very  interesting comments are in comments below.

Revision:

(April 22nd to 29thth, 2013.)

FENS 1

astdragon.org
BIODIVERSITY REFERENCE
British habitats
 
   Fens   
 
(page 1)

Distribution: Throughout the world wherever there is sufficient rainfall to support wetland communities. Scattered throughout Britain and Ireland, famously in East Anglia, but often in fragmentary state.

View across litter fields, Wicken Fen, Cambridgeshire, July 1997. The litter fields here are cut annually or biennially and are dominated by grasses such as Purple Small-reed (Calamagrostis canescens) and Purple Moor-grass (Molinia caerulea, especially subsp. arundinacea). They contain a rich diversity of tall herbs. Creamy-white patches of Meadowsweet (Filipendula ulmaria) are visible in the distance and beyond is carr with Buckthorn (Rhamnus cathartica) and Grey Sallow (Salix cinerea subsp. cinerea) along with Birch (Betula pubescens).

DEFINITIONS

An immediate problem in providing any brief summary of fens is that ecologists themselves differ in how they use the term. Firstly it is necessary to distinguish “fen” as an ecological term from “Fenland” as a geographical entity.

Fenland, a geographical area of East Anglia
Geographically, Fenland is the ancient area of marshes on the vast floodplain that surrounded the rivers Witham, Welland, Nene and Ouse (and their subsidiaries) that drain much of central and eastern England and flow into the Wash between Norfolk and Lincolnshire. It is or was an area of several hundred square miles (3800 km2 according to Good & Ratcliffe, in Ratcliffe, 1977), and in postglacial times evidently continued much further still into what is now the North Sea. It extended from Lincolnshire in the north to Norfolk in the southeast, encompassing much of the geographical (no longer political) county of Huntingdonshire and part of Cambridgeshire.
Perhaps one indication of the immensity of the area is the myth and legend surrounding Hereward the Wake, an ancient “Robin Hood-like” folk hero or outlaw who operated out of the Fens and who fortunately has not yet been subjected to the same recent historical and cultural media travesties as Robin Hood.

Little of this ancient area now exists. Most is now arable farmland, a flat landscape of huge fields and drainage dykes, with few natural hedges and with scattered, surprisingly isolated human communities. A few fragments remain to provide most of our finest British examples of “fen” as an ecological concept. These include Chippenham Fen and Wicken Fen in Cambridgeshire and Holme and Woodwalton Fens in Huntingdonshire, all of which are National Nature Reserves, though Wicken Fen, the most accessible of these, is owned and managed by the National Trust.

Although this present account is wider in concept, examples and photographs here are currently all from the geographical Fenland. An excellent account of the history, ecology and present/past management of fens by Godwin (1978) refers entirely to Fenland.

Though outside Fenland as defined here, there are a number of named fens stretching further east in Norfolk across to the Norfolk Broads, generally as parts of valley mire complexes. Many of the fenland rarities are or were to be found in both areas.

Fens as an ecological concept
Ecologists regularly use the word “fen” but establishing a precise definition is more difficult, reflecting the diversity and continuity of habitat and vegetation types. Generally, however, use of the term equates to the majority of topogenous mires, where local relief results in permanently high water tables, as on flood plains and in shallow depressions, or in transitional zones of vegetation bordering open waters. Smaller areas of fen may also occur within soligenous mires associated with routes of moving drainage water. It is understood here that any type of mire is generally characterised by peat formation, i.e. the build up of incompletely decomposed organic matter under conditions of waterlogging and negligible diffusion of oxygen, though in fact, as Wheeler & Proctor (2000) emphasise, some soligenous fens accumulate little or no peat, though are otherwise similar in hydrochemistry and vegetation.

The East Anglian fens are characterised by alkaline conditions resulting from water draining from chalk and other calcareous rock formations. They (and similar examples elsewhere) may be distinguished as “rich fen“, though there is often a general understanding that a “fen” will be relatively eutrophic (nutrient rich). A classic plant of rich fen is Saw-sedge (or simply “Sedge”) (Cladium mariscus), which may be a key species in past or present management (see below). The definition of “fen” however often also covers sites with much lower mineral input and corresponding higher acidity; such areas may be described as “poor fen” and are commonly characterised by extensive development of Sphagnum moss carpets.

(It may be noted in passing that “poor fen” should not be confused with a “Poor’s Fen”, which at Wicken and elsewhere was a name given to a specific area of a fen where the village poor, lacking other rights, were still able to cut peat or harvest sedge.)
This variation and often imprecision of terminology has been examined by Wheeler & Proctor (2000), who make a number of recommendations. In examining a wide range of mire types they find a bimodal distribution of pH that backs up the rather vague existing concepts of “fen” and “bog”.

They consider fen to be defined by a pH generally above 6.0 and with relatively high levels of calcium and bicarbonate ions. The vegetation of such mires tends to be rich in herbs and ‘brown mosses’ (they cite DrepanocladosCampylium and Scorpidium, and Cratoneuron also should be included).

By contrast, bog is defined by a pH generally below 5.0, with low levels of calcium ions, and with chloride and sulphate ions as the main anions. Vegetation includes members of the heather family (CallunaErica etc.), cotton-grasses (Eriophorum) and other calcifuge (“calcium-avoiding”) members of the sedge family, and often an abundance of Sphagnum mosses.
On this definition, many examples of so-called “poor fen” or “acid fen” are better considered as “bog” and this gives a more satisfactory treatment of phases and microtopography in complex acid mire systems.
THE PLANT COMMUNITIES

A detailed account of British fen types and their plant communities is provided by Wheeler (1984). Only outline summaries are given here.
The communities recognised in the National Vegetation Classification are given by Rodwell et al. (1995).

Herbaceous fen (including open reed and sedge fens)
The open fens are usually dominated by tall reedlike grasses, such as Common Reed (Phragmites australis), Small-reeds (Calamagrostis species) or Purple Moor Grass (Molinia caerulea), or by tall sedges such as Carex acutiformis or C. disticha, or by Saw-sedge (Cladium mariscus), or locally by the Blunt-flowered Rush (Juncus subnodulosus). A variety of other tall herbs such as Meadowsweet (Filipendula ulmaria) may be present, perhaps along with declining rarities such as the Marsh Pea (Lathyrus palustris). Below the field layer is likely to be a layer of mosses, including Campylium and Cratoneuron species. This may be a transitional phase or may be maintained by appropriate management.

Marsh Pea (Lathyrus palustris)
A nationally scarce herb of rich fens, largely confined to eastern England and East Anglia and scattered in a very few coastal fens elsewhere. Lost through drainage (and perhaps nitrogen enrichment?) from many of its former sites (see Mountford in Stewart et al., 1994). Its narrow leaves are, however, very difficult to spot amongst tall fen vegetation and even when in flower it is often not a conspicuous plant. It may await discovery at other sites.
Photograph: Wicken Fen, July 1997.

Traditional management of many of the East Anglian fens has been the cutting of ‘Sedge’ (Cladium), primarily for thatch. Sedge is more flexible and durable than reed and was used for ridging reed-thatched roofs or, less often, for thatching entire roofs. It also had uses as kindling material and as a tough litter for floor coverings. Large areas were maintained for this purpose and the survival of undrained fen fragments no doubt has been due to the value of sedge as a crop. However, there is now much less demand and former sedge fens have in many cases been colonised by bushes to form carr. This has meant the local disappearance of many plants requiring these open conditions and is implicated in the extensive loss of invertebrates such as the Swallowtail Butterfly (see below). While there is still a small commercial demand, cutting sedge is now largely a conservation exercise. Management aims at, e.g. Wicken Fen, are not only to maintain sedge fens but also to reclaim areas from carr and extend the open communities.

Sedge (Cladium) fen, Chippenham Fen, Cambridgeshire, 1980
Saw-sedge (or “Sedge”) (Cladium mariscus)
On the edge of a drainage dyke.
Wicken Fen, July 1998.
Conservation volunteers cutting a sedge field at Wicken Fen, July 1997

The areas dominated by grasses such as Calamagrostis species or Molinia were traditionally cut as “litter” for animal bedding. Like the sedge fens they tend to be herb-rich and continued cutting on an annual or biennial cycle is required to maintain floristic diversity.

As noted above, poor fens (if considered “fens” at all) are likely to have a moss layer including or dominated by Sphagnum species. Purple Moor-grass (Molinia caerulea), Bottle Sedge (Carex rostrata) and the smaller sedges, such as C. echinata and C. nigra may predominate amongst the vascular plants.

Carr (wooded fen)
Succession to carr (wet scrub and swampy woodland) is usually to be expected except where active management maintains the open areas. Lowered water tables caused by drainage within or adjacent to the fen complex may accentuate this and since most surviving fens are surrounded by farmland, this may be a substantial management problem.

Bushes and trees forming carr must be capable of growing in waterlogged conditions with little oxygen supply to the roots. Willows and sallows (Salix species) may predominate, including Grey Sallow (S. cinerea subsp. cinerea), which often dominates East Anglian fens and occurs more locally north to central Scotland.

Grey Sallow (Salix cinerea subsp. cinerea) carr, Wicken Fen, July 1997. The butterfly is a Comma (Polygonia c-album).
Comma (Polygonia c-album)
The same individual as shown in the photograph above. The Comma is by no means exclusively a fen butterfly, indeed it is widespread and locally common across much of southern England and Wales, but carr woodlands seem to suit it. No doubt this is partly because its main foodplant, the Stinging Nettle (Urtica dioica) is usually present in some abundance on the carr margins and along the droves (cut pathways).
There is some evidence it is currently increasing its range northwards, with recent scattered records in southern Scotland (including one individual in riverside scrub here in Paisley during the 1990s).

Two buckthorn species, the Common or Purging Buckthorn (Rhamnus cathartica) and the Alder Buckthorn (Frangula alnus) are also locally abundant carr species in some of the East Anglian Fens. Common Buckthorn is not confined to fen carrs; it can be a component of scrub on dry chalk slopes. Alder Buckthorn is more restricted to damper habitats.

Alder Buckthorn (Frangula alnus) in mixed carr, Wicken Fen, July 1998.

At Wicken, both were abundant in the first part of the 20th century and Rhamnus still is, locally being the dominant carr species. Frangula, however, suffered a decline through apparent fungal attack in the 1930s and has suffered other misfortunes since (Friday, 1997). It is currently a typical pioneer species in young carr and appears to be recovering its former status.

Alder (Alnus glutinosa) is a larger tree that may come to dominate richer fens in some localities. It is notable as possessing rood nodules containing a symbiotic nitrogen-fixing actinomycete. Nitrogen may otherwise be deficient during development of fen woodland.
In poor fen, the shrub Bog Myrtle or Sweet Gale (Myrica gale) is no doubt even more important as another species that effects nitrogen enrichment via symbiosis.

On poorer sites, Downy Birch (Betula pubescens) is likely to become the dominant tree species, sometimes forming more or less pure woodland on the thicker peats.

Birch carr with Downy Birch (Betula pubescens), here with Saw-sedge (Cladium mariscus) dominating the ground vegetation but no doubt suffering from the drying and more shaded conditions. Photograph: Holme Fen, Huntingdonshire, 1967.

FENS TWO

lastdragon.org
BIODIVERSITY REFERENCE
British habitats
 
   Fens   
 
(page 2)

ACCESS: DROVES AND WATERWAYSAs already indicated, most large fens have a past history of extensive management. Small fens or those in valley mires may be relatively natural, but a history of peat cutting or sedge harvesting requires routes of access. Water levels in the same fen systems have required control. Consequently the geographical Fenland has an ancient system oflodes, navigable waterways, some apparently dating back to Roman times. Subsidiary to these are dykes, which when clear may be able to take small boats, and additional drainage ditches. Cut routes through the fen are droves and again some are at least a few hundred years old. They provide a continuing short turf habitat and may support a flora of small sedges, rushes and herbs that cannot compete in taller vegetation.

Wicken Lode, an ancient, continually navigable waterway, now mainly used by holiday barges. It is bordered by the Lode Bank, a drove which itself is of substantial age. It is higher and dryer than most of the Fen droves, which are often temporarily flooded in the winter months. Wicken Fen, Cambridgeshire, May 1998.

The waterways are of great importance for their aquatic fauna and flora. The smaller dykes and ditches are readily colonised by submerged and floating-leaved aquatic plants, including, in rich fens, populations of local or rare stoneworts (Charophyta). The invertebrate fauna may be equally diverse. Further colonisation by taller aquatic macrophytes such as the Common Reed (Phragmites australis) is likely and the probability is that the dykes will become clogged with vegetation and silt. At length they may be crossable on foot and their value for water management, and indeed for their fauna and flora is lost. A cyclic programme of clearance maintains the waterways and ensures continuing habitat for rare species.

Water Violet (Hottonia palustris) amongst other aquatic macrophytes colonising a drainage dyke. Wicken Fen, May 1998.

CONSERVATION

Open water and flood-plain mires have probably been more extensively destroyed by man in Britain than those of any other class. This is especially true of the once vast swamps and marshes of the East Anglian Fenlands, occupying the large shallow basin of the three main rivers draining to the Wash. Many others have been reclaimed for agriculture, since the richer types of fen peat give a very fertile soil when dried out, and a great many have been partly drained or modified by human activity.
(Goode & Ratcliffe, in Ratcliffe, 1977)

Ratcliffe does go on to make the point that the Norfolk Broads owe their present existence to human activity. Large scale cutting of peat in the Middle Ages formed extensive hollows that have flooded and undergone succession, now forming important habitats from open water to rich fen and carr.

Mire surfaces are often sensitive to disturbance and uncontrolled public access can cause considerable damage to vegetation and to ground nesting birds. Trampling damage can be reduced by provision of boardwalks, which also have the effect of controlling the route taken by casual visitors.

Wicken Fen, being (mostly) owned by the National Trust, is managed to allow public access, which must then be balanced against conservation necessities. A circular nature trail via boardwalks takes visitors through most of the main habitats, permits access to the windpump and bird hides and ensures minimal damage to the Fen. Effectively the boardwalk is also a bridge across much of the wetter ground and (usually) means that waterproof footwear is not necessary. Wicken Fen, July 1998.
This particular section of the boardwalk has been replaced and re-routed since the taking of this photograph.

The dramatic loss of fenland habitat has taken its inevitable toll with regard to the specialist plants and animals of such habitats. Senecio congestus, the Marsh Fleawort, was once a plant of fen ditches in the Lincolnshire and East Anglian fenlands but is long extinct. A second Senecio species, S. paludosus, the Great Fen Ragwort, was also thought long extinct until a very few plants appeared on a cleared ditchbank in Cambridgeshire in 1972, evidently from long-buried seed. The population has been maintained and plants have been transferred to a safer location, though it is reasonable to expect that the surviving British stock is genetically impoverished. Other plants such as the Fen Orchid, Liparis loeselii and the Fen Violet, Viola persicifolia are critically endangered.

Predictably there are a number of birds confined to fen habitats. The East Anglian fens are the main British stronghold of the Bearded Tit (Panurus biarmicus), a species of reed-beds. Savi’s Warbler (Locustella luscinoides) is another reed-bed species that once bred in the Fenlands before becoming extinct in Britain. It has re-established itself in Britain since the 1950s, with Wicken Fen being a key site. The Marsh Harrier (Circus aeruginosus) is arguably the special bird of prey of the East Anglian fens. After coming close to extinction from use of cyclodiene agricultural pesticides, populations are now recovering following banning of these chemicals from agricultural use.
THE RÔLE OF THE ENTOMOLOGISTS

It was, however, the entomological interest of the East Anglian fens that first led to preservation of surviving fragments as nature reserves. The strong interest, particularly in butterflies and moths, during the 1800s meant that not only were the fens much visited, but also that sedge cutters were able to supplement their incomes by finding and selling larvae of the more sought after species. As the old Fenlands were turned so rapidly into productive agricultural land, it was the entomologists who first seem to have realised the value of holding onto and preserving some remnant of the old watery wilderness. The Swallowtail butterfly became a symbol of such efforts, though as it turned out, “preservation” of its remaining Cambridgeshire location was not enough, conservation through management was also needed and was sadly lacking in the early years of the 1900s. Other species, such as the Large Copper butterfly and the Reed Tussock moth were already extinct in Britain before any thought was given to conserving the Fens.

The Swallowtail (Papilio machaon) is now confined in Britain to the Norfolk Broads, though it was once also a classic butterfly of the geographical Fenland and persisted at Wicken Fen until the 1950s. Its distribution is necessarily limited by that of its foodplant, the Milk Parsley (Peucedanum palustre), which itself is a nationally scarce species, virtually confined to the old Fenland and the Norfolk Broads and extinct in most of the northern part of its range.

The Milk Parsley is a plant of rich fen, growing in sedge and litter fields and dependent on suitable cutting regimes. There have been several attempts to reintroduce the Swallowtail to Wicken Fen and management of the sedge and litter fields has included maintenance of its foodplant as a priority. However, past encroachment of carr has reduced the suitable area and it seems that at the present time the remaining area is too vulnerable to both drying and flooding for the Swallowtail population to remain viable. Clearance of some of the carr is a management priority, though it may be noted that a successful introduction from Norfolk will not replace the loss of genetic diversity. Dempster et al. (cited by Heath et al., 1984) carried out a museum study that suggested that Wicken butterflies were genetically somewhat different from those of Norfolk, a not unlikely result of the fragmentation of the old Fenland habitat.

It should also be noted that there are early records of the Swallowtail in Britain that suggest a much wider distribution in southern England and perhaps use of a broader spectrum of foodplants such as the relatively common Wild Carrot (Daucus carota) (Morris, 1870). Whereas the endemic British subspecies, Papilio machaon britannicus, is strictly a fenland butterfly feeding only on Milk Parsley, the widespread continental subspecies, Papilio machaon bigeneratus, is less restricted in its diet. It is possible these early records simply represent occasional vagrants from the continent, but it was collected in some numbers at least in Dorset. The Swallowtail had been locally abundant in the Fenlands of Huntingdonshire and Cambridgeshire but there were already concerns for its survival in the latter part of the 1800s. As the fens became the last refuge of this butterfly in Britain, perhaps isolation then further defined our endemic subspecies?
The illustration is taken from Morris (op. cit.) and was based on an 1851 Cambridgeshire specimen.


[To be added: accounts of the Large Copper & Reed Tussock. Ecotypic adaptation and genetic consequences of human disturbance in the Fen Nettle.]

FURTHER INFORMATION

Wicken Fen is the best documented fenland site, as well as being an area in which the author has a research interest, so has been much cited in this web profile. Much more is to be found at:

Wicken Fen Vision
http://wicken.org.uk
The official site (National Trust) of the Wicken Fen National Nature Reserve, with the management plan and plenty else on this area of ancient fenland. There was an older site, formerly at http://www.demon.co.uk/ecoln/wicken_fen/index.html (English Nature) which contained a wealth of information. Though sadly gone, it is archived at the Wayback Machine (insert the URL and wait …).
Fungi of Wicken Fen
http://www.lastdragon.org/wicken/wickenfungi.html   (link temporarily unavailable)
Primarily of research and specialised interest, but gives some extra background to habitats in the Fen.

For a very comprehensive account of Wicken Fen, its history, management and natural history, see Friday (1997). It has much of great relevance to fens in general. A detailed account of the history and past management of Wicken Fen is also given by Rowell & Harvey (1988).

Godwin (1978) gives an excellent account of the history of Fenland, with much on past and present management and conservation. Goode & Ratcliffe (in Ratcliffe, 1977, chapter 8) give an excellent overview of British peatlands including fens, their diversity and conservation criteria. Volume 2 of the same work summarises key British fenland sites selected as grade 1 or grade 2 SSSIs. A valuable compendium of detail, if somewhat outdated now, was provided by Tansley (1939). For a modern overview of mires, with a rigorous examination of terminology, see Wheeler & Proctor (2000).

References:

  • Friday, L., (ed.) (1997). Wicken Fen: the making of a wetland nature reserve, Harley Books, Colchester.
  • Godwin, H., (1978). Fenland: its ancient past and uncertain future, Cambridge University Press, Cambridge.
  • Heath, J., Pollard, E., & Thomas, J., (1994). Atlas of butterflies in Britain and Ireland, Viking, Harmondsworth.
  • Morris, F.O., (1870). A history of British butterflies, 3rd ed., Bell and Daldy, London.
  • Ratcliffe, D.A., (ed.) (1977). A nature conservation review, vol. 1, Cambridge University Press, Cambridge.
  • Rodwell, J.S., et al., (1995). British plant communities. 4Aquatic communities, swamps and tall-herb fens, Cambridge University Press.
  • Rowell, T.A., & Harvey, H.J., (1988). The recent history of of Wicken Fen, Cambridgeshire, England: a guide to ecological development. Journal of Ecology 76: 73-90.
  • Stewart, A., Pearman, D.A., & Preston, C.D., (1994). Scarce plants in Britain, JNCC, Peterborough.
  • Tansley, A.G., (1939). The British Islands and their vegetation, Cambridge University Press, Cambridge.
  • Wheeler, B.D., (1984) British fens – a review, in Moore, P.D., (ed), European mires, Academic Press, London.
  • Wheeler, B.D., & Proctor, M.C.F., (2000). Ecological gradients, subdivisions and terminology of north-west European mires. Journal of Ecology 88: 187-203.

Note: Like much of this site, these pages are likely to be the object of continuing development and review.

Fens AA

FENS

1.  General Introduction

Fen: a fen  is a type of wetland, broad expanse of nutrient-rich, ground-fed  shallow water in which dead plants do not fully decay, resulting in a flora of emergent plants growing in saturated peat. The other 3 types of wetlands are bogs, swamps, and marshes.

Fens can be drained but this can cause problems. Some major English fens were drained in the 1600`s. However, their early success was short-lived. Once drained of water, the peat shrank, and the fields lowered further. The more effectively they were drained, the worse the problem became, and soon the fields were lower than the surrounding rivers. By the end of the 17th century, the land was under water once again. While drained, however, fens are very productive in agricultural terms.

Wicken Fen

The best example in England of an undrained (but managed) English Fen is the Wicken Fen established by the National Trust in 1899. On 1 May 1899, the National Trust purchased two acres (8094 m²) for £10.

Although it is often described as a natural wilderness, it is neither—humans have been closely involved in this fen for centuries and the reserve is managed intensively to protect and maintain the delicate balance of species which has built up over the years. Much of the management tries to recreate the old systems of fen working which persisted for hundreds of years, allowing species to become dependent on the practices. For example the Sedge plant, Cladium mariscus, is harvested every year and sold for thatching roofs. The first recorded sedge harvest at Wicken was in 1414. Ever since then, sedge has been regularly cut. This has allowed a pattern of plants and animals to build up who depend on regular clearance of the sedge to survive. Many plants and animals are dependent upon regular management of vegetation in this way to keep their habitats going. Konik Ponies and Highland cattle have now been introduced to parts of the fen to prevent scrub from regrowing as a part of the management plan.

The present appearance of Wicken Fen is the result of centuries of management by human beings. Many of the practices now undertaken have changed little since medieval times. In surrounding areas, the landscape has changed so completely that it is almost impossible to imagine how it must once have all looked. Only a very few places survive where it is possible to experience this primitive landscape first hand; Wicken Fen is one of these.

Tracks in and around Wicken Fen became visible on Google Street View before many towns and urban areas in Britain were covered. Try it: http://maps.google.co.uk/maps?rlz=1C1GGLS_en-GBGB360GB360&sourceid=chrome&q=wicken%20fen&um=1&ie=UTF-8&sa=N&hl=en&tab=wl

170px-Wicken_Fen_Windpump

The National Trust aims to acquire further land as it becomes available, paying the market prices.[7] As a result of the increased area of wetlands, the populations of skylarks, snipe, grey partridge, widgeon and teal have all increased with a major increase in barn owls and short-eared owls. Buzzards, hen and marsh-harriers have returned, and bitterns began breeding by 2009 for the first time since the 1930s.[9]

The Wicken Fen Vision has great support from many people and organisations. Large sums of money have been raised from grant-awarding bodies, and from individual donors.

A Carr Fen is swampy.

carr, the name of which is derived from the Old Norse kjarr, meaning a swamp, is a type of waterlogged, wooded terrain that, typically, represents a succession stage between the original reedy swamp and the eventual formation of forest in a sub-maritime climate.[1]

The carr is one stage in a so-called hydrosere: the progression of vegetation beginning from a terrain that is submerged by fresh water along a river or lake margin. In sub-maritime regions, it begins with reed-swamp. As the reeds decay, the soil surface eventually rises above the water, creating fens that allow vegetation like sedge to grow. As this progression continues, riparian trees and bushes appear and a carr landscape is created–in effect a wooded fen in a waterlogged terrain. At this stage the pH is not too acidic and the soil is not too deficient in mineral elements. Characteristic trees include alderwillow and sallow.[1]

FEN MANAGEMENT

ONE: General.  from plantlife.org

Wetland

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Wetlands form over any land whose soil is either seasonally or permanently waterlogged. This can happen alongside rivers, across floodplains, where there are springs and seepage, a high water table or tidal incursion.

Water-logging tends to exclude oxygen from the soil and plants have evolved many ways to deal with this, leading to the evolution of hundreds of specialist wetland and waterside species.

Wetland habitats include marshes, fens, bogs, water-meadows and any muddy place by water; they are found all across the UK and often include systems of aquatic habitats such as ditches, rills and streams which can also be important for plants. Wetland complexes such as the Broads, Somerset and Pevensey Levels, form extensive networks of habitats which are rich in many other forms of wildlife.

Habitat features

Bogs

Upland and Lowland bogs are characterised by the dominance of Sphagnum moss species, which lay down layers of bog peat as they grow. Sphagnum acidifies its own environs and so bog systems are populated with plants that can cope with base-poor, acid waters. English upland blanket-bogs cover more than 10,000 hectares of land and are hugely significant in the landscape. Lowland bogs are much less extensive, are more fragmented and prone to damage; our largest extent, in the Humberhead levels, has been badly damaged in recent decades as a consequence of peat removal at an industrial scale

Fens and reedbeds

This kind of habitat occurs in river valleys and floodplains that are not conducive to the development of Sphagnum dominated vegetation. Sedges and ruches tend to dominate and common reed is a prominent species, although its abundance is greatly affected by management; fens and reedbeds have a very long history of traditional management, some being grazed but many cut for ‘fen litter’ or ‘marsh-hay’, a product that went for feed and bedding for the many thousands of horses that once populated our towns and cities. Fen-litter and saw-sedge, another traditional fen product, are both cut in late summer, which suppresses reed growth; however winter cutting encourages reed growth and leads to such dominance that the reed can be harvested in bulk for thatching. Most fens are small, isolated and restricted to the margins of larger wetland systems; however large areas are still to be found in the Broads and the Cambridgeshire Fens.

Wet woodland

Mature wet woodland is a rarity in the UK and where it does exist it is often restricted to the margins of fens and marshes and the fringes of slow moving rivers. Typically dominated by alder or willow, it can be a species-rich habitat, especially where it occurs at one end of a complete transition from open water to woodland; a few such examples can be found in the Broads. Wet woodland also occur away from obvious water supplies, for instance in Suffolk where alder woods occur on the poorly drained plateau clays.

Water meadows and wet grasslands

Although often badly affected by agricultural improvement, these grasslands can form extensive systems in river valleys and the lower parts of river floodplains. Associated with traditional extensive grazing regimes, where intervening ditches are maintained as ‘wet-fences’, such grassland networks form some of our most intact wetland systems. Good examples can be found all around the country and include the Pevensey and Somerset Levels, the floodplains of the Itchen and Test rivers in Hampshire and the Thames in Oxfordshire and parts of the Broads in Norfolk and Suffolk. Many such systems support the last of our species-rich lowland meadows but even where these are not as good as they once were, the ditch networks that divide them up can still be rich in aquatic and marginal plants

Key issues

Perhaps the single most influential factor in the loss of wetlands is drainage. Wetland soils, particularly fen peats, make fine agricultural soils if the water can be got rid of. This has of course already happened across many tens of thousands of hectares of former wetland habitat, with unfortunate consequences in terms of soil loss through oxygenation and shrinkage, windblow and carbon release.

The flower-richness of wetland habitats is dependent also on good water quality. Where wetlands are fed by rivers which pass through towns and cities and intensively farmed agricultural areas, high nutrient concentrations in the water cause a few species to outgrow the majority, leading to a rapid decline in floral diversity.

Abstraction of water from underground sources can reduce supplies of water to spring fed systems such as valley fens and chalk-stream margins. This leads to a gradual drying out, loss of water-dependent species and ultimately to complete loss of the wetland habitat. Water-levels can often be restored quite quickly, with the withdrawal of abstraction, but this does not necessarily lead to a restoration of former vegetation, mainly due to the oxygenation and breakdown of formerly water-logged soils.

Changes in agriculture and the way people live their lives has led to a decline (and in some cases almost complete loss) in markets for traditional fen produce. This has led to fens becoming uneconomic to manage in the traditional way, leading to conversion to agriculture or abandonment.

What we’re doing about it

Plantlife’s Fenlands Project, supported by Esmee Fairbairn and Natural England, conducted experimental management at a range of sites in the East of England to a) enhance populations of priority fen species and b) encourage the reappearance of fen plants at degraded fens. Experimental work finished in 2009 but monitoring work continues to track the response of plants to the experiments over time.

TWO: Technical

A good manual illustrates how complex this can be:

The Fen Management Handbook Edited by Andrew McBride, Iain Diack, Nick Droy, Bobbie Hamill, Peter Jones, Johan Schutten, Ann Skinner and Margaret Street

Introduction and Basic Principles
Fens are magical places; they are an essential part of our
cherished landscape. They support a rich variety of wildlife, and
are often a repository of evidence of many generations of past
economic use and management. With so much in their favour, it is
perhaps surprising that fens are one of the least well recognised
habitats, and a part of our countryside which most people
understand little about.
This handbook has been produced to improve understanding
of fens and how they function, to explain why fens need
management and to provide best practice guidance. Case
studies are included at the end of most sections as practical
examples of the principles and techniques outlined in the text.
The handbook is aimed at anyone interested in fens, or who might
become involved in fen management, creation or restoration from
a practical, policy or planning perspective.
Key points and good practice are highlighted in green boxes.
Cautions about activities which might be legislatively controlled
or which might potentially damage the interest of fens are
highlighted in red boxes.

Snapshot case studies in the text to
illustrate specific points are highlighted in yellow.
1.1 What are fens?
The word ‘fen’ is derived from the old English word ‘fenn’ meaning
marsh, dirt or mud.

A fen is a wetland that receives water and nutrients from surface and/or
groundwater, as well as from rainfall.

Differentiating between fens and bogs
Fens receive most of their water via rock and soil which contain
dissolved minerals creating growing conditions that allow more lush
vegetation than bogs.
Bogs receive water exclusively from rainfall which is acidic and contains
very few minerals; consequently rain-fed acid bogs support a less
diverse range of vegetation than fens.
Fens are found from sea level up into the hills, across the whole of the British
Isles. They range in size from tiny flushes of only a few square metres, to extensive
floodplain fens covering hundreds of hectares, forming important features in the
wider landscape and river catchments. 8
1.2 What’s so special about fens?

Fens were prized by our ancestors for the range of products they yield: reeds and
sedge for thatching, willow for basketry, hay and lush aftermath grazing for cattle.
It is the past management and human interaction with fens for such purposes that
has created the extremely diverse and ever-changing habitat which attracts and
supports a rich variety of plants, insects, mammals and birds, and which explains
why fens are described as semi-natural rather than natural habitats.

Section 2:
Fen Flora and Fauna explains more about the flora and fauna which make fens so
special from a wildlife perspective.
The UK contains a large proportion of fen types found in Europe, the surviving
fragments of previously much more extensive wetlands. ‘

In his book The Illustrated History of the Countryside, Oliver Rackham suggested that “about a quarter of the
British Isles is, or has been some kind of wetland.”

As in other parts of Europe, the
quality and extent of wetlands including fens has declined dramatically as a result
of drainage, development and neglect. Some of our best agricultural soils have
been provided by fens, following drainage and decades of tillage. However, the
organic component of the soil that makes it so suitable for root and other crops has
gradually broken down releasing carbon and lowering the land level, making the
land more difficult to drain.
It is estimated that of 3,400 km2
of fen present in England in 1637, only 10 km2
remains today.

In intensively farmed lowland areas of England, fens now occur less
frequently, are smaller in size and are more isolated than in other parts of the UK.
Despite these losses, the UK still boasts some large fens such as the 300 ha Insh
Marshes in the floodplain of the River Spey in Scotland, the calcareous rich-fen and
swamp of Broadland covering 3,000 ha in Norfolk and Suffolk, and the Lough Erne
system in Northern Ireland with extensive areas of fen and swamp. In some lowland
areas, such as the Scottish Borders and southern parts of Northern Ireland, there
are large numbers of fens which although small (many less than 3 ha in size), are
still of European importance for the rich wildlife they support.

FEN PLANTS

Yellow Flag

220px-Iris_pseudacorus_001

Greater Pond Sedge: carex riparia800px-Carex_riparia_(Ufer-Segge)_IMG_22812

Common Spike Rush

In pools

[edit]In typical fen

[edit]In fen carr

Kjarr

carr, the name of which is derived from the Old Norse kjarr, meaning a swamp, is a type of waterlogged, wooded terrain that, typically, represents a succession stage between the original reedy swamp and the eventual formation of forest in a sub-maritimeclimate.[1]

The carr is one stage in a so-called hydrosere: the progression of vegetation beginning from a terrain that is submerged by fresh water along a river or lake margin. In sub-maritime regions, it begins with reed-swamp. As the reeds decay, the soil surface eventually rises above the water, creating fens that allow vegetation like sedge to grow. As this progression continues, riparian trees and bushes appear and a carr landscape is created–in effect a wooded fen in a waterlogged terrain. At this stage the pH is not too acidic and the soil is not too deficient in mineral elements. Characteristic trees include alderwillow and sallow.[1]

Canadian Expertise.

http://www.gret-perg.ulaval.ca/fileadmin/fichiers/fichiersGRET/pdf/Doc_generale/Wetlands.pdf