Designing Pocket Wetlands

 "Reconciliation is more than words and involves the restoration of good relations with the Earth, including the waters... Every human has a responsibility to preserve, protect, and conserve the waters. We all come from water, and therefore all have a relationship to water. Reconciliation includes learning to understand the relationship to the waters, to respect the waters for providing life, and maintain a reciprocal healthy relationship to the waters. This will guide true sustainable water governance.
Susan Chiblow, Reconciling our relationships with the Great Lakes

Where land holds water, a wetland forms: marsh, floodplain, wet meadow, vernal pool, riparian edge. Kingston is a city of wetlands within the Katarokwi Watershed. Katarokwi means the clay, the mud, the material that water makes and moves. In the Haudenosaunee creation story, clay is the material from which human bodies were fashioned and placed on the earth. 

Why create a pocket wetland 

Often when we hear about wetlands and the importance of preserving them, we hear about why they're important from a human-centric point of view. What if we were to take Water's point of view? Or the point of view of all of the other beings with whom water is in relationship — plants, birds, bees, wasps, flies, dragonflies, macroinvertebrate, soil, foxes and so many more? 

No wetland, no pond is an island. For dragonflies, damselflies, and toads, an ecological corridor means a network of ponds — a pondscape — across Kingston. The more pocket wetlands within reach, the richer the life in each. Every new pocket wetland strengthens the pondscape. From Pondful:

"A pondscape is a group of ponds, often of different sizes, shapes and depths, spread across the landscape to form a network. A pondscape provides habitats for more species than a single waterbody of the same size  —  and multiple ecosystem services for people. Pondscapes may comprise anything from a handful to hundreds of ponds. Biologically, the ponds will form a habitat network, even if they are not physically connected to each other, because freshwater plants and animals are adapted to dispersing between them, forming a landscape with ponds."

Pocket wetland design principles

While pocket wetlands are one of the best ways to increase biodiversity, there's no 'best' design. Each one matters. Each one contributes to the pondscape. Each one, if managed for biodiversity, has the possibility of being ecologically unique.

“We don’t want every pond to be the same, we want a wide range of environmental conditions. This has been recommended before for terrestrial garden management and could now be taken further to include water habitats."

Site with intention 

Site the pond at a natural low point where water already pools after rain. You can use the workbooks provided in G3 group's watershed approach to landscaping. Consider the trade-offs between sun and shade. Small ponds heat up quickly in full sun, encouraging algae, while shade moderates temperature but limits plant selection. Choose a location where you can enjoy the life your pond brings — a window, a deck, or a favourite corner of the garden.

Shape the land around the pond

Use the soil you dig out to build gentle mounds and berms around the pond, creating topography that supports different plant communities. Use berms to channel rainwater into the pond and to keep road salt runoff out. Plan a spillway so that heavy rain has somewhere to go. Armour your spillway with stones or gravel to prevent erosion.

Vary the depth

Create a shallow zone (10–40 cm) for plants to root, amphibians to lay eggs, and nymphs to emerge. Dig a deeper zone (60–80 cm+) to hold water during drought, support nymphs of species like Green Darner who spend several years underwater before emerging, and to anchor floating-leaved plants like White Water-lily (Nymphaea odorata) and Yellow Pond-lily (Nuphar variegata).

Carve soft, sloped edges

Dragonfly and damselfly nymphs need emergent stems rooted in the shallow sloped edges to crawl up when they emerge as adults. Salamander larvae and froglets need that same gradual slope to transition from water to land.

Create a living bed

Midge larvae, mayfly nymphs, and dragonfly nymphs like Widow Skimmer all live in soft sediment. If you have heavy clay soil, compact the bottom and sides to hold water. If you need to use a pond liner, add a layer of sand or fine gravel on top.

Keep fish out

Dragonflies, Wood Frog, American Toad, Blue-spotted Salamander, and Fairy Shrimp all breed in fishless water. Fish eat their eggs, nymphs, and tadpoles. They also eat Daphnia, the tiny crustacean that grazes algae and keeps the water clear. Without Daphnia, algae take over, light no longer reaches the bottom, and the underwater plants that larvae and nymphs hide in and hunt from die. The pond looks fine to a female laying eggs, but her nymphs won't survive.

Plant emergent vegetation

Dragonflies and damselflies choose where to lay their eggs based on the plants growing along the water's edge. Plant diversity increases dragonfly diversity.

Design for seasonal change

Vernal ponds usually dry up in July or August. This seasonal cycle keeps fish from establishing, allowing dragonflies, American Toad, and Wood Frog to breed successfully. Fairy Shrimp eggs lie dormant through the dry season and hatch when the pond refills in spring. If you want to support dragonfly nymphs like Green Darner who take several years to develop, ensuring part of the pond is at least a metre deep and compacting the clay will help the pond hold water through drought.

Planting the pocket wetland

Plants bring a pocket wetland to life. The zones you plant, the plants you choose, and where you locate them shape the beings who find the pocket wetland. Plants give dragonflies somewhere to lay eggs, nymphs a ladder out of the water, tadpoles somewhere to hide, and Daphnia the shade they need to keep the water clear.

Shrubs for perching, foraging, structural complexity 

• Buttonbush (Cephalanthus occidentalis) Round, fragrant flower heads July–August for pollinators and Ruby-throated Hummingbirds. Seeds for songbirds and waterfowl. Tolerates standing water.
• Red Osier Dogwood (Cornus sericea) White flower clusters in June for pollinators. White berries in July for birds. Brilliant red stems in winter.
• Winterberry (Ilex verticillata) Late winter berries for over-wintering birds including Robins and Cedar Waxwings.
• Pussy Willow (Salix discolor) Important for early pollinators. Hosts over 450 Lepidoptera species. 
• Speckled Alder (Alnus rugosa) Nitrogen-fixer. Seeds for Goldfinches, Redpolls, and siskins in winter.
• Swamp Rose (Rosa palustris) Pink flowers June–July loved by bumble bees. Rose hips for over-wintering birds. 
• Spicebush (Lindera benzoin) Early yellow flowers in April before the leaves open. Bright red berries in late summer for migrating birds. Host plant for Spicebush Swallowtail Butterfly. 

Wet edge plants for birds, froglets, and emerging nymphs

• Marsh Marigold (Caltha palustris) One of the first wetland flowers of spring, blooming in May. Popular with Syrphid flies.
• Palm Sedge (Carex muskingumensis) Arching leaves over the water's surface. Spreads slowly by rhizomes. 
• Cattail Sedge (Carex typhina) Arching leaves over the water's surface. Spreads moderately by rhizomes, monitor. 
• Water Avens (Geum rivale) Nodding pink-orange flowers in May–June. Seeds loved by Goldfinches.
• Cardinal Flower (Lobelia cardinalis) Blooms July–August. A favourite of Ruby-throated Hummingbird. Short-lived, but self-seeds.
• Swamp Milkweed (Asclepias incarnata) Blooms July–August. Host plant for Monarch Butterfly. Supports many specialist bees and Great Gold Digger and Black Gold Digger wasps.
• Swamp Rose-mallow (Hibiscus moscheutos) Spectacular large pink flowers July–September.
• Swamp Aster (Symphyotrichum puniceum) Blooms September–October. Late-season nectar source for migrating Monarchs.
• Bog Goldenrod (Solidago uliginosa) Blooms August–September. Supports dozens of specialist bee species and Lepidoptera.
• Nodding Beggar's Ticks (Bidens cernua) Annual. Blooms August–October, supporting late season pollinators. Seeds attach to feathers and fur.
  
• Jewelweed (Impatiens capensis) Annual. Blooms July–September. A favourite of Ruby-throated Hummingbirds. 

Shallow water plants for egg-laying and nymph emergence

• Soft Rush (Juncus effusus) Round, pliable stems. Eastern Forktail, Familiar Bluet, and other damselflies insert their eggs into the stems. Spreads by rhizomes. Divide clumps to control spread.
• Blue Flag Iris (Iris versicolor) Blooms June, attracting Ruby-throated Hummingbirds. Blade-like leaves are an emergence ladder for damselflies and dragonflies. Brown-belted Bumble Bee is one of the few bees with a tongue long enough to reach the nectar.
• Arrowhead (Sagittaria latifolia) Blue-spotted Salamander attaches egg masses to submerged stems. Dragonfly nymphs crawl up the stems to emerge. Mallards eat the tubers. Divide to manage spread.
• Pickerelweed (Pontederia cordata) Dragonflies and damselflies lay eggs on the stems. Nymphs use them as emergence ladders. Seeds eaten by waterfowl. Specialist relationship with Pickerelweed Bee (Dufourea novaeangliae), Pickerelweed Longhorn Bee (Melissodes apicatus), and Worthy Longhorn (Florilegus condignus). Divide to manage spread.

Surface plants for shade and shelter

• Greater Duckweed (Spirodela polyrhiza) Shades the surface. Eaten by waterfowl. Dormant buds sink to the bottom in fall, re-emerging in spring. Remove clumps to prevent dense mats from blocking light.
• White Water-lily (Nymphaea odorata) Blooms June–September. Fragrant white flowers open in the morning and close at noon. Leaves provide surface cover for nymphs. Can form dense colonies in a small pond. Plant in a submerged container to control spread.
• Yellow Pond-lily (Nuphar variegata) Blooms June–September. More structurally complex than White Water-lily. Submerged stems shelter nymphs. Common in Ontario lakes and ponds. Less aggressive than White Water-lily in small ponds.

Submerged plants for oxygenation and underwater habitat

Nymphs, tadpoles, and salamander larvae hide in and hunt from submerged plants. Weigh roots down with stones to avoid adding nutrients to the water.

• Canadian Waterweed (Elodea canadensis) Fast-establishing oxygenator. Provides dense underwater structure for nymphs and tadpoles. Spreads aggressively under favorable conditions and can choke a small pond. Thin regularly throughout the growing season. Poses no invasion risk in a closed garden pond with no outflow to natural waterways.
  
• American Water-milfoil (Myriophyllum sibiricum) Feathery submerged stems provide nymph refuge. 

Meet Lakeside's Dragonfly Lair

Meet Dragonfly Lair, Lakeside’s new vernal pond. We situated this pond just immediately north of Lakeside's Little Forest.

Vernal ponds — temporary wetlands that dry up in summer or fall — are some of the most biodiverse and undervalued habitats in the urban landscape. Josh Cowan, who led the design and construction of the pond, trained in watershed restoration with Dr. Rajendra Singh, the Waterman of India. He calls vernal ponds — temporary wetlands that dry up in summer or fall — some of the most biodiverse and undervalued habitats in the urban landscape. 

"If you didn't know better, you might not recognize raindrops and rivers as kin, so different are the particular and the collective."
Robin Wall Kimmerer, Witness to the rain