Appendix 1. Dragonfly Habitats in Northern British Columbia

There is a wide variety of aquatic habitats available to dragonflies in northern British Columbia. A general overview is presented below, with a few of the distinctive dragonfly species associated with each. The wetland site association classification used is that of MacKenzie and Moran (2004); pertinent parts are summarized in Table 2 below. Dragonfly associations are much broader than plant site associations, largely because dragonflies (in both adult and larval stages) appear to react to the structure of plants and plant communities rather than plant species.

Some species, such as Libellula quadrimaculata, have such wide tolerances that almost any standing freshwater body half a square metre or larger in any habitat is adequate for breeding. On the other hand, Aeshna subarctica requires submerged moss for larval habitat. And although it requires peatlands of a certain structure (peatlands characterized by shallow pools supporting short sedges, such as Carex limosa and C. livida), Aeshna sitchensis apparently does not discriminate if the pond is in an acid coastal bog dominated by Sphagnum mosses and ericaceous shrubs with Carex livida in the pools (Wb52) or if the habitat is a neutral interior fen with a Drepanocladus moss mat, shrubby willows and Carex limosa in the pools (Wf08). In this case the plant lists from the two places will be radically different, but the dragonfly community will show much less variability. For this reason, at least, the occurrence of any dragonfly species overlaps many of the wetland site associations described in MacKenzie and Moran (2004) and the following discussion is kept relatively general and only the more common and obvious site associations are mentioned.

1. Large lakes (wave-washed shores with little vegetation)
Many northern lakes, such as Fraser, Purden and Moberly lakes, to name only a few, have wave-washed shores with little aquatic vegetation. In some sheltered situations, sparse stands of bulrushes (Schoenoplectus acutus, Wm06) or horsetails (Equisetum fluviatile, Wm02) may occur. The dragonflies associated with this habitat are: Enallagma carunculatum (in bulrush beds), E. ebrium, Aeshna umbrosa, Ophiogomphus severus and Somatochlora cingulata. In larger, deeper lakes (Fig. 20), such as Atlin, Babine and Stuart lakes, the waters are colder and less productive, and dragonflies are restricted to shallow waters in sheltered bays, where the fauna resembles that found in small lakes and ponds.

Figure 20. Tatlayoko Lake, Chilcotin. A large lake with little aquatic vegetation.
Photo: Robert A. Cannings.

2. Small lakes and ponds with floating, but little emergent, vegetation)
A wide variety of small lakes and ponds are present in the North. Those lacking emergent vegetation of any significance often support Nuphar lutea - Utricularia macrorhiza communities (Fig. 21). Yellow pond-lily ecosystems occur on a variety of sites from deep (5 m) lakes with gravel bottoms to shallow, acidic, peat-degradation pools in coastal bogs (MacKenzie and Moran 2004). In lake habitats, a diverse array of Odonata occurs: Enallagma ebrium, Aeshna canadensis, A. eremita, A. palmata, A. tuberculifera, A. umbrosa, Cordulia shurtleffi, Somatochlora albicincta, S. cingulata, Leucorrhinia glacialis, L. hudsonica, L. proxima, Ladona julia and Sympetrum obtrusum.

Figure 21. Mitten Lake, Kispiox. A small lake with Nuphar lutea association.
Photo: Gord Hutchings

3. Saline lakes
These salty lakes occur primarily in grasslands and open forests on the plateaus of the Chilcotin and Cariboo (Fig. 22). Site associations in the saline meadows adjacent to the lakes and ponds include Juncus balticus (Wm07) marshes, Distichlis spicata var. stricta (Gs01), Puccinellia nuttalliana - Hordeum jubatum (Gs02) and Carex praegracilis (Gs03) associations. Some dragonfly species are able to live in this unusual habitat despite the often high salinity, and their life histories enable them to take advantage of the ephemeral nature of the shallower lakes and ponds: Enallama boreale, E. clausum, Lestes congener, L. unguiculatus, Sympetrum internum, S. corruptum and S. costiferum. These species are not restricted to this habitat.

Figure 22. Rock Lake, Riske Creek, Chilcotin -- a saline lake.
Photo: Robert A. Cannings

4. Ephemeral ponds (temporary ponds)
In addition to some saline ponds that may disappear during hot weather, fresher ephemeral waters in the southern parts of the study area (Fig. 23) support the following species: Lestes dryas, L. unguiculatus, Sympetrum internum, S. madidum and S. pallipes. Some of these species overwinter as eggs in the dry pond basin. These habitats may represent a wide range of site associations, e.g., Schoenoplectus acutus (Wm06), Eleocharis palustris (Wm04), and Juncus balticus (Wm07) marshes.

Figure 23. Grassland pond near Rock Lake, Riske Creek, Chilcotin.
Such ponds often dry completely in summer.
Photo: Robert A. Cannings

5. Cattail/bulrush marshes (including margins of lakes, streams and ponds)
Marshes are permanently to seasonally flooded non-tidal mineral wetlands dominated by emergent grass-like vegetation. Low species diversity is typical with strong dominance by one or two aggressive species that spread vegetatively (MacKenzie and Moran 2004). Tall stands of cattails (Typha) and bulrushes (Schoenoplectus) are most common in nutrient-rich, warm waters at lower elevations having warm, dry summers. They are most common in the southern parts of the region. Typha latifolia marshes are designated Wm05 (Fig. 24); Schoenoplectus acutus ones are Wm06 (Fig. 25). Species associated with these habitats are: Lestes congener, L. disjunctus, L. dryas, L. forcipatus, L. unguiculatus, Coenagrion angulatum, Enallagma annexum, E. carunculatum, Ischnura cervula, I. perparva, Aeshna canadensis, A. interrupta, A. palmata, Anax junius, Rhionaeschna californica, R. multicolor, Leucorrhinia intacta, Libellula quadrimaculata, Sympetrum costiferum, S. danae, S. internum, S. obtrusum and S. pallipes.

Figure 24. Blackburn Lake, Fort St. James. Typha marsh.
Photo: Robert A. Cannings, RBCM

Figure 25. Pond near Como Lake, Atlin. Schoenoplectus marsh.
Photo: Gord Hutchings.

6. Sedge marshes
Carex utriculata - Carex aquatilis marshes (Wm01) (Fig. 26) represent the most common and widespread marsh association in BC. This community is frequent on sites inundated by shallow low-energy floodwaters that have some drawdown in the late season. They include flooded beaver ponds, lake margins and floodplains. This association is found on mineral soils rather than on peat (the fen equivalent, Wf01); in general, Wm01 is more deeply flooded, has a more dynamic hydrology and has a higher cover of C. utriculata (MacKenzie and Moran 2004). The Equisteum fluviatile - Carex utriculata association (Wm02) is similar and occurs more on lake margins and floodplains where there is more water movement. Some swamp associations such as Ws02, Ws04, Ws05 and Ws06 also may be related. Typical species in these habitats are: Lestes congener, L. disjunctus, L. dryas, L. forcipatus, Coenagrion resolutum, Enallagma annexum, E. boreale, Nehalennia irene, Aeshna canadensis, A. interrupta, A. palmata, Anax junius, Epitheca canus , E. spinigera, Somatochlora semicircularis, S. hudsonica, Libellula quadrimaculata, Leucorrhinia borealis, L. hudsonica, Sympetrum internum and S. obtrusum. Other types of sedge marshes have similar dragonfly faunas.

Figure 26. Lake at head of Yahwa Creek, Mackenzie. Carex utriculata - Carex aquatilis marsh.
Andrew Harcombe and Tim Vogt collecting Aeshna juncea.
Photo: Robert A. Cannings.

7. Small peatland ponds with aquatic moss
Peatlands are poorly drained wetlands where decaying moss and other vegetation accumulates as peat. Bogs are nutrient-poor peatlands where ericaceous shrubs and hummock-forming Sphagnum mosses form distinctive communities adapted to highly acid and oxygen-poor soils. The rooting zone is isolated from mineral-enriched groundwater (MacKenzie and Moran 2004). Fens are nutrient-medium peatlands dominated by non-ericacious shrubs, sedges and brown mosses, where mineral-bearing groundwater is within the rooting zone. A few examples of site associations are Carex limosa - Menyanthes trifoliata - Sphagnum bogs (Wb13), Ledum groenlandicum - Kalmia microphylla - Sphagnum bogs (Wb50), Juniperus communis - Trichophorum cespitosum - Rhacomitrium lanuginosum bogs (Wb52), Betula nana - Menyanthes trifoliata - Carex limosa fens (Wf07) and Carex limosa - Menyanthes trifoliata - Drepanocladus fens (Wf08). Standing, open water occurs in many of these habitats; in these ponds and pools, especially if there is floating and submerged moss, (Fig. 27) a special group of dragonflies may occur along with species having wider ecological tolerances: Coenagrion interrogatum, Aeshna. septentrionalis, A. subarctica, Somatochlora kennedyi, S. septentrionalis, Leucorrhinia patricia. A few of the more important specific peatland types are summarized below.

Figure 27. Heckman Pass, western Chilcotin. Peatland ponds with
submerged and floating aquatic moss.
Photo: Robert A. Cannings.

8. Water Sedge-Beaked Sedge fens
Sedges (Carex) form dense stands in water-saturated areas or around many lakes and ponds. The most common site association type is Wf01 (Carex aquatilis -- Carex utriculata fens) (Fig. 28). It occurs from low to subalpine elevations on sites that are annually inundated by shallow, low-energy flood waters. They occupy wetter zones in larger peatlands but also form extensive pure meadow-like basins (MacKenzie and Moran 2004). Some swamp associations such as Ws02, Ws04, Ws05 and Ws06 also may be related. Some dragonfly species associated with this habitat are Lestes congener, L. disjunctus, L. dryas, L. forcipatus, Coenagrion resolutum, Enallagma annexum, E. boreale, Nehalennia irene,A. interrupta, A. palmata, Anax junius, Somatochlora semicircularis, S. hudsonica, Libellula quadrimaculata, Leucorrhinia borealis, L. hudsonica, Sympetrum internum and S. obtrusum

Figure 28. Carex aquatilis - Carex utriculata fen near Takla Landing.
Andrew Harcombe collecting.
Photo: Robert A. Cannings.

9. Slender Sedge fens
Common on peat flats surrounding small lakes and ponds or in infilled basins. Prolonged shallow surface flooding is typical. Common associations are Wf05 (Carex lasiocarpa - Drepanocladus aduncus fens) and Wf06 (Carex lasiocarpa - Menyanthes trifoliata fens) (Fig. 29). Shrubs such as Salix pedicellaris, S. candida and Betula nana can occur.

Wf06 has less flooding and greater peat saturation than Wf05; the former almost always occurs as a floating mat adjacent to a lake or pond. This habitat supports a diverse species list, including Lestes disjunctus, Coenagrion interrogatum, C. resolutum, Nehalennia irene, Anax junius, Aeshna subarctica, Leucorrhinia hudsonica, L. proxima and Sympetrum obtrusum. Along the open edge of the water body, or in associated pools, A. septentrionalis, A. subarctica, A. tuberculifera, Somatochlora kennedyi, S. septentrionalis, Leucorrhinia patricia, among others, may occur.

Figure 29. Carex lasiocarpa fen at Bear Lake, north of Prince George.
Photo: Robert A. Cannings.

10. Shallow sedge/moss fens: Betula nana - Menyanthes trifoliata - Carex limosa (Wf07) and Carex limosa - Menyanthes trifoliata - Drepanocladus (Wf08) associations
Peatlands affected by flowing water, evenly vegetated with low sedges and shallowly flooded or dotted with shallow pools only a few centimetres deep (Figs. 27, 30, 31). Carex limosa rooted in shallow water is the constant characteristic of Wf08 (Fig. 30), which is typical of patterned fens host a particular assemblage of species: Lestes disjunctus, L. congener, L. forcipatus, Enallagma boreale, Coenagrion resolutum, Nehalennia irene, Aeshna septentrionalis, A. sitchensis, A. tuberculifera, Somatochlora brevicincta, S. franklini, S. kennedyi, S. semicircularis and S. whitehousei, Leucorrhinia hudsonica and Sympetrum danae. Widspread species and those noted in #9 above may also occur.

Figure 30. Patterned fen at Williams Creek Ecological Reserve, Terrace.
Photo: Robert A. Cannings.

Figure 31. Fen near Takla Landing.
Photo: Robert A. Cannings

11. Outer Coastal bogs
Bogs on the outer coastal lowlands form a blanket mire complex on level or sloping terrain (Fig. 32). Hypermaritime climate, high precipitation and humidity and mineral-poor bedrock produce these bogs. The Pinus contorta - Empetrum nigrum - Sphagnum austinii site association (Wb51) and Juniperus communis - Trichophorum cespitosum - Rhacomitrium lanuginosum (Wb52) association are typical and are perhaps the most important for Odonata. Stunted Pinus contorta, Chamaecyparis nootkatensis and Thuja plicata are common; shrubs such as Empetrum nigrum, Myrica gale, Ledum groenlandicum and Juniperus communis are common. Ponds and pools usually have firm, peaty margins. Lestes disjunctus, Enallagma boreale, Aeshna interrupta, Aeshna sitchensis, Cordulia shurtleffii, Somatochlora albicincta, Leucorrhinia hudsonica, Libellula quadrimaculata and Sympetrum danae are typical species.

Figure 32. Tow Hill Bog, Graham Island, Queen Charlotte Islands. A coastal Sphagnum bog.
Photo: Robert A. Cannings.

12. Streams
Odonata are not normally found in the cold streams of mountainous areas. The following species, when living in flowing waters, are generally restricted to rather warm, slow streams or montane streams that drain lake basins (Fig. 33), beaver ponds or peatlands: Ophiogomphus colubrinus, Ophiogomphus severus and Aeshna umbrosa. The latter two species also live in lakes. Somatochlora minor inhabits small montane streams and S. walshii lives in streams or slowly flowing water in peatlands. Yet to be found in the region, but to be looked for, Cordulegaster dorsalis is found in many warm streams draining lakes on the west side of the Coast Mountains south of 52º. It is known from coastal Alaska and from spring-fed streams in the southern Interior.

Figure 33. Tezzeron Creek, Fort St. James. Andrew Harcombe
hunting Ophiogomphus colubrinus.
Photo: Robert A. Cannings.

13. Springs and shallow seeps
Some of the more uncommon species of Odonata are associated with small springs and shallow seeps. Amphiagrion abbreviatum is known from only one locality in the region in such habitats. In the northern fringes of its range, Ischnura damula is normally restricted to warm springs, such as Liard River Hot Springs (Fig. 34). Somatochlora forcipata is apparently restricted to spring-fed streamlets through sloping fens. Potential habitat occurs in subalpine fens such as Salix barclayi - Carex aquatilis - Aulacomnium palustre (Wf04) and Eriophorum angustifolium - Caltha leptosepala (Wf12). Tanypteryx hageni larvae burrow in seepage areas in coastal fen associations such as Eriophorum angustifolium - Sphagnum (Wf50).

Figure 34. Liard River Hot Springs.
Photo: Robert A. Cannings.

Table 2. Site Association Information (after MacKenzie and Moran, 2004)