Newsletter of the Biological Survey of (Terrestrial )

Border Conflicts: How Leafhoppers Can Help Resolve Ecoregional Viewpoints in Canada and the USA K.G.A. Hamilton Agriculture and Agri-Food Canada, Ottawa, ON K1A 0C6 [email protected]

Reprinted from Newsletter of the Biological Survey of Canada (Terrestrial Arthropods) Volume 28, No. 2, pp. 41–54

(This newsletter is available online at http://www.biology.ualberta.ca/bsc/english/newsletters.htm) Vol. 28, No. 2 41

Border Conflicts: How Leafhoppers Can Help Resolve Ecoregional Viewpoints in Canada and the USA

K.G.A. Hamilton Agriculture and Agri-Food Canada, Ottawa, ON K1A 0C6 [email protected]

Abstract Introduction coregions are defined using different Biologists from the days of Darwin have Eparameters and assumptions in Canada and been fascinated by biogeographic patterns of the USA. The only ecoregion composite (pub- biota. Early classifications of North Ameri- lished in 1999) minimizes the differences but can floras and faunas (summarized in Scudder needs to be tested against an impartial data set 1979) emphasized climate and dominant veg- spanning the borders. Leafhoppers, which are etation as ruling factors in such regional pat- speciose in the northern states and southern terns. Biotic maps in Canada are usually based Canada, have been extensively collected and on 12 forest regions (e.g., Hosie 1969) while analysed for distribution patterns. These pat- in the U.S.A. the dominant vegetational types terns tend to follow those of their plant hosts, were designated as 106 regions of “potential and therefore reflect ecoregional patterns of natural vegetation” (Küchler 1964). Other clas- lower trophic levels. In general, leafhopper dis- sifications stressing endemism are little used tribution patterns agree with the 1999 synthesis in Canada since postulated glacial refugia are but differ in some significant details, especially considered significant only for arctic and alpine on the prairies where agriculture has exten- , having been too close to glaciers to sively disrupted presettlement ecosystems. account for most of Canada’s endemic species found in more temperate areas (Scudder 1979, fig. 3.44). Instead, substrate has been used as a measurable test for the extent of 15 large

Fig. 1. Southern Canadian Ecozones (Smith et al. 1996) compared to biomes in adjacent U.S.A.

42 Newsletter of the Biological Survey of Canada (Terrestrial Arthropods) biotic areas in Canada (Fig. 1). These areas holdings to approximately 300,000 identified are called Ecozones, and their subdivisions specimens. are Ecoprovinces, Ecoregions and Ecodistricts Analyses have been published of “short- (Smith et al. 1996). A subsequent analysis com- horned” bug faunas for the islands of New- bined these various criteria into a single map foundland and Cape Breton in Nova Scotia of North American terrestrial Ecoregions (Fig. (Hamilton and Langor 1987), for the Yukon 2) based equally on regional distinctions and (Hamilton 1997a), and for the Prairie Ecozone endemism (Ricketts et al. 1999). The compilers (Hamilton 2004a, b) while unpublished synop- did not provide lists of biota upon which it was ses have been prepared for each of the other based, but seem to have emphasized botani- southern ecozones. These studies find consid- cal and vertebrate distributions with other data erable cross-border disjunctions in the present from some beetles and macrolepidoptera. It is Ecoregional classification. Evidently, new data evidently a compromise classification using a is needed to bring cohesion to the ecoregions of mixture of criteria with many of the Canadian southern Canada and the northern U.S.A. “Ecoprovinces” converted into equivalents of “Ecoregions” further south. Understanding biogeographic patterns This study examines a rich fauna of insects Ecoregions are based on two kinds of data not previously utilized in defining regional bio- that correlate well with both biotic and abiotic tas. Records are based mainly on specimens ecological conditions: overall biodiversity and of leafhoppers and their relatives, or “short- regional endemism. In this study, large-scale horned” bugs (Fig. 3) in the Canadian National patterns of overall biodiversity emerge (Maw Collection (CNC), Ottawa. Arctic and subarc- et al. 2000) and high levels of endemism and tic areas were sampled in 1947-1961 during the some curiously disjunct populations are noted Northern Survey at 64 arctic and subarc- in specific areas of Canada (Bouchard et al. tic localities (Cody et al. 1986). Boreal and far 2002; Paiero et al. 2003; Hamilton 1995, 2002a, north sites represented in the CNC were mapped b, 2004a). by Huckett (1965, figs. 1-7) and representation of southern localities typical of “short-horned” Regional faunas vary with ecological con- bugs are summarized by Hamilton (1982, map ditions in various distinct ways that may be 1). Since 1963, 45 years of sampling leafhop- interpreted through the relative proportions pers (: Cicadellidae) and related of endemics to total biodiversity. Simple cli- insects at more than 1000 sites across Canada nal distributions (e.g., from wet to dry areas) and the northern U.S.A. has increased CNC will support both the highest biodiversity and highest endemism in places of optimal condi-

Fig. 2. Ecoregions of southern Canada and the northern USA (Ricketts et al. 1999).

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Fig. 3. Examples of families of short-horned bugs in Canada. Cicadidae: Okanagana ornata Van Duzee, found in California, Oregon and at D’Arcy, B.C.; Cicadellidae: Zygina flammigera (Fourcroy), a wind-dispersed microleafhopper imported from Europe to coastal B.C.; : Clastoptera atrapicata Hamilton, a B.C. endemic; Membracidae: Ceresa alta Walker, a North American pest; 5, : Otiocerus degeerii Kirby, restricted to southern localities; : Synecdoche constellata (Ball), a Pacific coast species also known from two inland sites; : Toya propinqua (Fieber), a migratory introduced species; : Oliarus coconinus Ball, a disjunct in the Okanagan Valley; Fulgoridae: Scolops abnormis Ball, an endemic of the Okanagan Valley; Caliscelidae: Bruchomorpha beameri Doering, a prairie species also widespread in the intermontane valleys of B.C.

Photographs courtesy of Gernot Kunz, Tom Murray, Charles Schurch Lewallen and Werner Eigelsreiter.

44 Newsletter of the Biological Survey of Canada (Terrestrial Arthropods)

Fig.4. Total biodiversity and diversity of endemics as a measure of biotic systems across environmental gradients (e.g., aridity). Ecoregions may have clinal distributions of environmental conditions, in which case both biodiversity and endemism are expected to be highest in areas with least severe conditions. Recently developed overlaps between ecoregions (ecotones) share total faunas, so biodiversity is higher than in either ecoregion alone, but endemics are rare. Where the reverse is true (endemism high, biodiversity low) the evidence points towards a relict biota. But where environmental conditions fluctuate greatly, both the fauna and flora are reduced to only highly tolerant and widespread species, and a biotic hiatus results.

tions, usually those far removed from extremes hiatus of low biodiversity and also low ende- (Fig. 4, cline). Such distributions are common micity occurs (Fig. 4, hiatus). within ecoregions. If, however, the biodiversity “Well-developed ecotonal communi- and endemism are both highest near both ends ties” differ from most ecotones in containing of the ecological cline, as happens across the endemics adapted to an admixture of condi- boreal forest zone with maximum numbers of tions (Odum 1971) such as prairie grasses species and endemics in Newfoundland (Ham- growing in partial shade, or foraging ilton and Langor 1987) and in Beringia (Hamil- in open areas but retreating to forested patches ton 1997) then at least two separate ecoregions for nesting. Well developed communities of are represented along the gradient. Where bio- endemics in ecotonal conditions indicate that diversity is high on either side of an anomalous these conditions have lasted for much longer area, and endemism is highest in that anomaly periods than the present interglacial and are (Fig. 4, relict), this represents a site where a therefore equivalent to ecoregions. It is nota- former ecoregional fauna persists embedded in ble that “” (ecotonal between an unfavorable ecological area, such as a san- prairie and boreal forest) has one of the richest dhill surrounded by land overgrown with for- faunas of endemic short-horned bugs in Can- est. If the fauna of two biomes overlap at an ada. A second such ecotone rich in endemics ecotone or “tension zone,” biodiversity will be is the belt of sand plain, alvar and oak savan- higher there than in either adjacent area (Odum nah extending from Lake Huron to the interlake 1971), but endemism should be lower (Fig. 4, district of . This area contrasts with ecotone). This study reports a rare additional that found in the prairie-forest transition zone case: where climate cycles over a multi-year extending from southern Ontario to Texas, the periodicity, as does rainfall on the Canadian habitat of the massasauga rattlesnake Sistrurus steppe (Sauchyn et al. 2004), endemic species catenatus (Ref.), but few other endemics. Two characteristic of adjacent areas cannot establish other and much less biodiverse well-developed populations adapted to either extremes, and an

Vol. 28, No. 2 45 ecotonal communities (with several endemic under bark. All these suctorial insects together species each) exist. One of these is along the form a sizeable portion of the Canadian insect upper Fraser River and its tributary the Thomp- biomass. They probably supply a large part of son in central , where aspen the diet of insect and arachnid predators and parkland species from the coexist parasites. They are thus important in nutrient with inland forest species and a very few Great cycling. Leafhoppers, and of the Basin endemics. The other is the island of family Delphacidae, are particularly impor- Newfoundland where both boreal and temper- tant in wetlands and shorelines as they include ate-zone species have adapted to a hemiboreal numerous grass and sedge-feeding species. environment. All four of these ecotonal com- “Piglet bugs” (Fulgoroidea: Caliscelidae) are munities are equivalent to ecoregions and are almost exclusively grass and sedge-feeding more clearly demarcated in their short-horned insects that may be found commonly through- bug fauna than are other communities around out southern Canada although their species are them. much fewer than those of other Fulgoroidea. Leafhoppers and their relatives are jump- Faunal description ing insects with powerful hind legs. They dis- “Short horned” bugs are traditionally perse largely by running and jumping, but they called Homoptera (more also disperse by flight even when most of the recently, Hemiptera suborders Archaeorrhyn- population are short-winged (“brachypterous”) cha and Clypeorrhyncha). They are readily and flightless. They have been recorded to identified by their small, bristle like - anten migrate over thousands of kilometres (Medler nae and tubular, hypognathous mouthparts. 1962; Cheng et al. 1979; Ghauri 1983) when (Cicadidae) are the largest “short aided by strong winds. Yet many species have horned” bugs. They are notable for their loud very restricted distributions: over 90 species of mating calls or “songs” and their subterra- leafhoppers plus 35 planthoppers, 8 treehop- nean nymphs (Hamilton 2009). Leafhoppers pers, 7 spittlebugs and 4 cicadas are known (Cicadellidae) are by far the most common and from only very small areas of Canada (Hamil- diverse of these insects and include most of the ton 1999a). This seeming contradiction appar- Hemiptera introduced into Canada, principally ently reflects the diversity of life styles found in from Europe (Hamilton 1983). Other families these insects and the necessity for differentiat- are spittlebugs (Cercopidae and Clastopteri- ing endemic species from widespread ones in dae), treehoppers (Membracidae) and plan- any faunal analysis. thoppers (Fulgoroidea). Probably over 1,500 species of “short horned” bugs inhabit Canada A great number of species of leafhoppers (Maw et al., 2000). This is less than 3% of the fly, but only few individuals of most species are total estimated insect fauna of Canada (Danks found in flight intercept traps. The main excep- 1979). Other bugs are estimated to have more tion to this rule is the genus Xestocephalus than 2,500 species in Canada, but half of these which appear to be ant-guest insects; apparently are (Aphidoidea) and plant bugs (Miri- adults fly actively near ground level in search dae) with perhaps only about 50% of the spe- of ant nests. Traps more than 1 metre above the cies known. Fully 93% of the “short horned” ground collect few leafhoppers, mainly long- bug fauna in adjacent states of the U.S.A. has winged species of Macrosteles (Waloff 1973), been recorded from Canada, indicating a well- at least some of which are known to be migra- studied Canadian fauna suitable for regional tory (Chiykowski and Chapman 1965). Tree faunal evaluation. inhabiting species, especially “micro leafhop- pers” (Typhlocybinae) probably are dispersed Most “short horned” bugs feed on plant by wind much more than ground inhabiting spe- sap as adults. Nymphs of two small fulgoroid cies. Other tree canopy species are more com- families (Derbidae, Achilidae) feed on fungi monly collected in traps than species from low

46 Newsletter of the Biological Survey of Canada (Terrestrial Arthropods) vegetation, as the usual flight path of leafhop- although its native range is in the south-central pers is obliquely downwards. The rapidly dis- plains of the U.S.A. (Hamilton 1998, Map 13). persing exception seems to be sexually imma- ture individuals (Waloff 1973); possibly these Faunal composition actively disperse over short distances to pre- Southern Canada has seven Ecozones (Fig. vent inbreeding. By the time females become 1). The Boreal Shield is the most extensive eco- gravid they usually lose the power of flight. zone, but the forest classification of Canada (Hosie 1969) divides the Boreal Shield roughly Most migratory bugs are light-bodied at latitude 48°N, with the lower part assigned insects not more than 4 mm long that are eas- to the Great Lakes-St. Lawrence zone. The lat- ily carried by air currents. They usually show ter classification is preferred here because most modifications for flight: their wings are usually faunas of short-horned bugs (excepting only more than 4 times as long as wide, and (in Del- Achilidae and Delphacidae) decrease dramati- phacid planthoppers) their eyes are very large cally across the boreal forest divide, which cor- compared to the width of the head. Wind-car- responds to the 2500 degree-day isotherm for ried insects apparently include most microleaf- the growing season (National Atlas of Can- hoppers plus Balclutha spp. Only these and the ada, 4th ed., 1974, p. 50). A similar disjunction migrant “aster leafhopper” Macrosteles quadri- occurs between insular Newfoundland (except lineatus (Forbes) are excluded from the follow- for the Long Range Mountains) and Labra- ing biogeographic discussion. dor (Maw et al. 2000) at 50°N. This dramatic Many tropical species of planthoppers are decrease in the phytophagous fauna probably also migratory. Only a few of these are known corresponds to the open understory of conifer- from Canada, but one, Sogatella kolophon ous forests that has a very limited diversity of (Kirkaldy), which overwinters in the southern herbaceous plants. This study therefore focuses U.S.A. has been found as far north as Cape on the six parts of Canada that lie below lati- Breton Island. tude 48°N: insular Newfoundland, hemiboreal parts of the Boreal Shield, Atlantic Maritime The rate at which non-migratory leafhop- Ecozone (AME), Mixedwoods Plains Ecozone per populations spread is best observed in spe- (MPE), Prairies Ecozone (PRE), Montane Cor- cies imported by human activity. These “exot- dillera Ecozone (MCE) and Pacific Maritime ics” expand their ranges at rates between 10 and Ecozone (PME). 100 km/year (Hamilton 1983). Perhaps these figures may be upward extremes for leafhopper Insular Newfoundland has a boreal aspect vagility, as imported species are often the ones but coastal areas to the south and west have a most able to encroach on occupied areas. These strong admixture of 23 hemiboreal leafhoppers insects disperse readily by following introduced and 21 temperate-zone species (44 species in floras along transportation corridors. all) compared to 42 boreal species (Hamilton and Langor. 1987) for an overall hemiboreal Native species or ones which inhabit frag- aspect. There are also six species endemic to mented habitats appear to spread at much slower Newfoundland and adjacent land to the south- rates. For example, only one arctic species out west, in contrast to only four exclusive to Cape of 24 has been able to invade islands across Breton Island and two found around the Gulf of major water channels and a third of the arctic St. Lawrence. The presence of emergent land Alaskan-Yukon leafhoppers have not crossed on the adjacent Grand Banks during Pleisto- the Mackenzie River valley in the 12,000 years cene minimum sea levels (Fig. 5) must have since deglaciation (Hamilton 1997a). Some served as a glacial-age refugium for the distinc- native species have been spread unnaturally tive Newfoundland fauna. quickly by human activities; thus, for example, the Canadian clover leafhopper Ceratagal- The Maritimes or AME is divided into three lia humilis (Oman) is a pest in eastern Canada “ecoprovinces” which in turn are subdivided

Vol. 28, No. 2 47 into 14 “ecoregions.” The AME fauna of native highland areas. The highlands of Cape Breton “short-horned” bugs reflects to some degree are quite dissimilar from the other hemiboreal the broader geographical patterns expressed in areas in having a number of lowland disjuncts this classification, but not the finer subdivisions plus the majority of endemics in Nova Scotia. (Hamilton and MacQuarrie 2000, and Hamilton The fauna of Îles-de-la-Madeleine, QC is also in press). At least 285 species out of 425 have distinctive. Technically, these remote islands in limited dispersal opportunities and are truly the middle of the Gulf of St. Lawrence belong year-round residents in the AME. These most to the Northumberland Lowlands Ecoprovince, clearly support the designation of distinctive but they have a distinctive leafhopper and spit- “Ecoprovinces” within the AME. These “Eco- tlebug fauna (Hamilton 2002a). Their fauna of province” faunas are, indeed, more discrete 35 native and 7 introduced “short-horned” bugs than that of the AME itself. In this connection it is tiny compared even to the depauperate fauna is noteworthy that the North America-wide bio- of Prince Edward Island, which has 123 native diversity classification system (Ricketts et al. species and 19 European species. Still, it is sur- 1999) recognizes three separate “Ecoregions” prisingly rich considering the distance from but not the AME. They segregate the Northum- the mainland and differs significantly from berland Lowlands ecoprovince as a separate the Prince Edward Island fauna in consisting Ecoregion, and map the tip of Cape Breton primarily of species typical of the Gaspé. It Island in the same Ecoregion as most of New- also includes one strongly disjunct leafhopper, foundland, the north shore of the St. Lawrence, Rosenus acutus (Beamer), which is not other- and the highlands of Gaspé and New Bruns- wise known south or east of northern Manitoba. wick. The data from “short-horned” bugs sup- The biota includes a number of endemic forms port the separation of the lowlands, but do not and even a few endemic species. None of these support such a “lumping” of widely separated was probably able to weather the last glacial

Fig. 5. Pleistocene minimum sea levels 12,500 years before the present (BP) exposed many of the offshore banks near Nova Scotia (NS), New Brunswick (NB) and Maine (ME). Lower sea levels probably made a land connection to the Îles de la Madaleine and formed offshore refugia for hemiboreal insects and plants. Embayed shallow waters in the Gulf of Maine permitted mild temperatures and associated vegetation to invade New Brunswick until 5000 years BP.

48 Newsletter of the Biological Survey of Canada (Terrestrial Arthropods) period on these islands. Instead, they probably The Great Plains of Canada experienced came to the islands from the mainland at a time less detailed surveys than in the U.S.A. in the when glaciers had retreated enough to allow 19th century when the native vegetation of the a boreal forest to flourish (Fig. 5), yet before presettlement prairies was still extensive. Now, melting ice caps raised sea levels closer to their only fragments of the eastern half of this area present height, increasing the distance between still retains a semblance of its native grasses the islands and the mainland. and the original extent and character of the eastern “prairies” is almost entirely conjec- The Mixedwoods Plains Ecozone in tural. Ecoprovinces of the Prairie Ecozone are southern Ontario and the St. Lawrence Valley therefore based on soil types rather than veg- of Québec was mostly dense forest in presettle- etation, a measure more of the degree of aridity ment days, except where wetlands and sedge than of presettlement vegetation. Fortunately, marsh broke the canopy. The dominant bug leafhoppers, “piglet bugs” and delphacid plan- fauna of the MPE is therefore one that feeds thoppers are abundant, diverse and frequently on trees, understory plants and sedges, with a host-specific on native prairie plants. Three smaller component that feed on grasses associ- cicadas, one spittlebug, seven treehoppers, 47 ated with rocky outcrops and 14 boreal species planthoppers and 168 leafhoppers make up a found in scattered bogs. It is surprising there- fauna consisting of 55 species widespread on fore that 12% of the 563 native species is simi- the Great Plains, 39 species characteristic of lar to that of the prairies of western Canada and eastern plains (six species are found only in grasslands in the western or southern U.S.A. tall-grass prairie and seven on oak savannah), (Hamilton 1997b). Most of these 66 grassland and 132 species found on the drier western species are host-specific, showing that they “steppe” (Hamilton 2004a,b). The northward evolved in an area where grasses, alkaline- extension of tall-grass prairie into southern adapted sedges and other arid-adapted plants Manitoba in the vicinity of Morden, the warm- formed a dominant or subdominant part of the est part of the , continues into ecosystem. Peripheral zonation of this fauna eastern (Hamilton 2005). Of partly reflects milder climate near the Great the western fauna, 34 are widespread, 40 are Lakes and partly the presence of sand or lime- restricted to aspen parkland and 58 are found stone that maintains aridity throughout much of only on “short-grass” prairie. These distribu- the growing season. Fully 47 grassland species tions do not match the concentric patterns of are found in such coastal situations, 15 being the Ecoprovinces of the Prairie Ecozone (nor widespread, seven found only on the eastern of the Ecoregions that are based on these Eco- side of Lake Huron from the Bruce Peninsula provinces) but instead follow an anomalous to Ipperwash Beach and 12 are found only pattern (Fig. 6). An oak savannah fauna occu- from Grand Bend to Ipperwash. Many others pies most of the and vicinity are found near the southern tip of Ontario, or around southern Lake Manitoba northwest to on limestone plains (“alvars”) from Manitoulin Winnipegosis; a western fauna extends along Island in Lake Huron south to the Bruce Penin- the southern edge of the Ecozone as far as the sula and east to Ottawa (Bouchard et al. 2002, sandhills of western Manitoba, but this fauna Paiero et al. 2003). Similar faunas are found in drops off rapidly to the north. However, there northwestern and northeastern parts of southern is a major biodiversity “hot spot” of 92 prai- Michigan and in oak savannah from northeast- rie species at Elbow, Saskatchewan where the ern Illinois and southern Wisconsin diagonally Qu’Appelle Valley headwaters nearly meet the through Minnesota to eastern Manitoba includ- South Saskatchewan. Apparently the transverse ing the Tolstoi “tall-grass” prairie (Hamilton valley system represented by these two rivers 1995) at the southern tip bof the Boreal Plains (a relict of a glacial-age meltwater spillway) Ecozone. is a conduit between the arid western fauna, which inhabits its sun-parched south-facing

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Fig. 6. Distribution of endemic Homoptera on the Canadian prairies, with size of circle proportionate to biodiversity of site (a cross indicates 3 or fewer prairie-endemic species; total prairie fauna indicated if larger than 40). Sites are ranked as aspen parkland, tallgrass or shortgrass prairie according to insects that are host-specific.These affinities do not match existing ecoregions that are based on overall moisture gradients. slopes, and the eastern fauna which inhabits the valleys, and semiarid shrub-steppe in the south, moister valley bottom. All around this area is with Ponderosa pine woods as ecotone among tableland subject to wide and periodic changes all three and therefore commensurate with an from exceptionally dry to exceptionally moist extension of the interior forest ecoregion in the years. This highly volatile climate is suitable Pacific Northwest states. Ecodistricts 1002 and only for highly vagile, widespread plant feed- 1005 together (lower Fraser valley) are unique ing insects like leafhopper “tramps.” in the ME as their endemic fauna of four spe- cies probably came from the coastal intermon- The distinctive “aspen parkland” fauna tane valleys of Oregon and Washington states from the northern fringe of the prairies also by way of the Pacific Maritime Ecozone. extends into the Ecozone where it forms a disjunct fauna along the upper The short-horned bug fauna of the north- reaches of the Fraser River and extends as far ern end of the Pacific Maritime Ecozone shares south as Princeton, B.C. (Hamilton 2002b). with the adjacent parts of the MCE a large part This grassland fauna is quite distinct from that of its boreal and wide-ranging fauna. There is of the Pacific Northwest fauna that extends into a small component of coastal endemics, princi- the southern Okanagan Valley. Elsewhere, the pally around the Queen Charlotte Islands. Fur- Montane Cordillera Ecozone consists largely ther south the Pacific coast has more species of temperate forest valley bottoms embed- ranging northward from Oregon and Califor- ded in boreal forest-clad mountains (Hamilton nia, particularly on the southern tip of Vancou- 1999b). A total of 465 species of Homoptera- ver Island. A few species in this temperate-zone Auchenorrhyncha are reported from the Eco- mixed hardwood forest are species shared with zone. Of these, 157 are confined to valleys (138 the Palouse grassland of Washington state and of these occur in the Okanagan Valley); 28 are the Okanagan Valley that must have crossed the confined to mountains; and 148 are widespread Coastal Range by way of the Columbia River species of the boreal and hemiboreal zones. The in postglacial times. fauna is consistent with the recognition of three ecoprovinces: a widespread boreal forest fauna Discussion extending across Canada, a northern grassland Short-horned bugs provide clear evidence extension of the prairies that occupies the lowest of regional faunas in two aspects of southern

50 Newsletter of the Biological Survey of Canada (Terrestrial Arthropods)

Canadian biogeography where data is sadly altitudinal endemism is unlikely and fauna are lacking: the exact southern boundary of boreal scattered vertically by summer updrafts. On forest and the extent and nature of presettle- the other hand, reliance on surrogates such as ment grasslands. soil types divorces such analyses from direct faunal and floral comparisons provided by eco- Boundaries of ecoregions of ecotonal logical studies such as “potential natural veg- origin are usually ragged rather than continu- etation.” Ecoregional landscape patterns based ous (Newfoundland is the exception) but can on patterns of biodiversity and endemism but be mapped fairly easily as large-scale regions with precise boundaries governed by geologi- encompassing the particular sites with highest cal factors is a happy compromise between biodiversity. Boundaries of a hiatus are much these two systems. But ecoregional patterns more problematic because biodiversity though are very complex to analyse and only as good such regions is very low and therefore difficult as the data base on which they are founded. to characterize. In the case of the boundary Inclusion of the rich and geographically lim- between aspen parkland and arid plains in Sas- ited faunas of short-horned bugs is essential katchewan there is conflicting evidence between for a well-founded biogeographical assessment the prevalence of aspen and that of dominant that transcends national boundaries and offers a and subdominant grasses such as mat muhly, return to nested sets of landscape scales. Muhlenbergia richardsonis (Trin.) Rydb. The insects, on the other hand, show a sharp bound- Twenty-five ecoregions in Canada lie south ary across the area of least biodiversity where of Canadian Shield forest (Ricketts et al. 1999). the South Saskatchewan and Qu’Appelle Riv- Of these, five (7, 8, 27–29) lie partially or almost ers transect the area and bring these two faunal entirely within boreal forest as defined by the zones into direct contact with maximum diver- 2500 degree-day isotherm. The three western sity, a very narrow east-west ecotone. ecoregions (27–29) enclose deep valleys that support temperate-zone species and are there- Of all the ecoregions in Canada, the shrub fore included in this analysis. The two eastern steppe of the Okanagan is by far the most ecoregions (7, 8) lack such strong topographic clearly defined by its extraordinarily high bio- features and their insect biodiversity strongly diversity and endemism in a geographically supports their subdivision according to existing constricted area. Yet this faunal region cannot forestry maps (Hosie 1969). The faunal analysis be demarcated by its biota (83 endemic species according to endemism supports the following in the north and 73 in the south, with 37 species 15 redefined ecoregions that cross the Canada- in common). This is an exemplar of an ecore- USA border representing four biomes. The rest gional situation with a clinal distribution. Such of Canada’s ecoregions fit into the Arctic, Taiga ecoregions commonly have indefinite boundar- (subarctic, mostly above the 1500 degree-day ies. In such cases the boundaries of the ecore- isotherm) and Boreal biomes. gion must be set by factors other than biota, such as soil types, which permit precision. Hemiboreal and deciduous forest biome (Fig. 7: 1-7) Conclusions Ecozone classification of landscapes offers (eastern Canada) three advantages: (1) a nested set of regional 1. Hemiboreal zone or forest/boreal tran- landscapes at differing scales which simpli- sition (southern half of ecoregion 7-8) is fies interpretation and offers a broader choice consistent on both sides of Lake Superior, of descriptive options; (2) precise boundaries with a few endemics centrally located, suitable for conservation decisions and ecolog- mostly on the Upper Peninsula of Michigan ical management; (3) the “lumping” of altitudi- and adjacent Wisconsin. Its faunistics are nal zones in such mapping simplifies the data quite distinct from those of aspen parkland and works well in glaciated landscapes where

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(ecoregion 55) which forms a similar tran- the Grand Banks of Newfoundland, and a sition but with numerous grassland endem- distinctive coastal fauna of 12 species that ics scattered around the rim of the Great attenuates northward from the New England Plains from western Manitoba to central states. Its fauna is similar to that of the Colorado. Adirondack Mountains in New York state (part of ecoregion 8) from which it is sepa- 2. Newfoundland forms a distinctive hemi- rated only by the narrow Hudson Valley, but boreal ecoregion with a strong admixture distinct from the more southerly hemiboreal of both boreal and temperate-zone in- forest in Pennsylvania (ecoregion 15). sects along with four endemic leafhoppers (Hamilton and Langor 1987). 7. Gulf of St. Lawrence lowlands (ecore- gion 13) represents an isolated extension 3. Northern oak savannah (ecoregion 9 in of broadleaf forests found in coastal Maine Minnesota and Michigan) is consistent with (northern part of ecoregion 14) with mainly the eastern half of ecoregion 59 (“northern coastal endemics, some of which are widely tall grasslands”) in Manitoba, the southern disjunct from the New England fauna, most half of ecoregion 59 in Wisconsin (based on notably the Tibicen lyricen (DeGeer) early survey records) and the Manitoulin- that has been photgraphed on July 31, 2007 Bruce Peninsula limestone outcrops and at Richibuctou, NB. beach ridges around Lake Huron in Ontario. Most of its endemics are around Lake Michigan and its northwest extent (7 en- Montane forests biome (Fig. 7: 8-11) and demics) forms an ecotone with aspen park- land. The “boreal” fauna of the boggy strip Intermontane arid lands biome (Fig. 7: 12) of land south of Lake is included (western Canada) here because it is interspersed by sandy ar- eas that have a quite different, more south- 8. Pacific coastal forests (ecoregions 23, 24, erly aspect that supports a hemiboreal fauna 33, 34) have a fauna associated mainly with of leafhoppers and includes a relict oak sa- pine, sedge and alder. Three endemics are vanna around Tolstoi. found on the unglaciated Queen Charlotte Islands and adjacent mainland. 4. Southern Great Lakes forest (ecore- gion 10) has the greatest biodiversity of 9. Interior forests (ecoregions 25-30) ap- any ecoregion in Canada, but has only pear to be a northern extension of interior one endemic species, the very rare cicada forests of Oregon and western Washington Okanagana noveboracensis Emmons in the (ecoregions 37, 38) that became isolated as vicinity of Niagara Falls. The fauna is rich- interior shrub steppe spread during post- est at the tip of southern Ontario and adja- glacial warming. Its few endemics and cent Michigan. disjuncts in Canada are associated with ice front conditions during the last ice age (e.g., 5. Great Lakes lowland forest (ecoregion Psammotettix beirnei Greene in the vicin- 11) is consistent with the southern half of ity of Mt. Revelstoke is a sister-species of ecoregion 9, with a few endemic insects and P. alexanderi Greene in the vicinity of Mt. prairie disjuncts found mostly in the vicin- Washington in New Hampshire). ity of the Great Lakes. 10. Leeward forests (ecoregions 31, 32) en- 6. Acadian forest (ecoregion 12) is an iso- compass arid valleys which represent an ec- lated extension of hemiboreal forest on the otone of aspen parkland and shrub steppe, eastern side of the St. Lawrence lowlands. with 27 prairie disjuncts plus a few endemic It has six endemics mostly at its eastern tip insects confined to the upper Fraser Valley. closest to the presumed glacial refugium of

52 Newsletter of the Biological Survey of Canada (Terrestrial Arthropods)

11. Puget Sound forests (ecoregion 35) are Great Plains grasslands (Fig. 7: 13-15) probably a northern extension of Williamette 13. Aspen parkland (ecoregions 55-57 with Valley forests (ecoregion 6) with a postgla- southern boundary extending to the South cial influx of shrub steppe fauna which con- Saskatchewan and Qu-Appelle Rivers) rep- stitutes most of the endemic insects. resents a periglacial grassland that became 12. Palouse grasslands (ecoregion 53) is a disjunct from grasslands of the Colorado westward extension of montane grasslands mountains (ecoregion 45) when postglacial in ecoregion 43 (South Central Rockies) aridity eliminated much of the fauna from that differs sharply in its short-horned bug the intervening Wyoming basin (ecoregion fauna from that of the adjacent Great Plains, 77). There are 40 endemics plus unde- although the dominant grasses across the scribed Delphacidae scattered throughout passes are identical. This tiny area has an the region. enormous number of grassland endemic 14. Steppe or “mixed grasslands” (ecoregions short-horned bugs (275) and probably 56 and 58 south of aspen parkland) has represents a postglacial fusion of numer- most of its 58 endemic bug species in south- ous isolated grassland refugia (Hamilton eastern and adjacent Saskatchewan, 2002b). The southern Okanagan Valley is but there are isolated populations of west- enriched by 22 arid-adapted species from ern species as far east as western Manitoba, the shrub steppes (ecoregion 75) which in- and there are 34 prairie-endemic spe- vade sun-parched eastern slopes in the vi- cies in common with aspen parkland. The cinity of Okanagan Falls south to Osoyoos leafhopper fauna tapers off southwards, and another 24 extend their ranges into arid leaving some species in southern Canada areas north and east from there. widely disjunct from populations in Kansas (particularly significant are the flightless Attenuipyga balli Oman, and Pectinapyga

Fig. 7. Fifteen ecoregions south of the boreal zone supported by faunas of short-horned bugs.

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texana Osborn on buffalo grass, both found Hamilton, K.G.A. 1983. Introduced and native leaf- at single sites in Saskatchewan). hoppers common to the old and new worlds (Rhynchota: Homoptera: Cicadellidae). The 15. Prairie or northern tall grasslands (west- Canadian Entomologist 115: 473 511. ern half of ecoregion 59 and eastern part Hamilton, K.G.A. 1995. Evaluation of leafhop- of ecoregion 55) probably existed only in pers and their relatives (Insecta: Homoptera: the southern Red River Valley of Manitoba Auchenorrhyncha) as indicators of prairie pre- where the degree-days of the growing sea- serve quality. pp.211-226 In D.C. Hartnett, ed., Proceedings of the Fourteenth Annual North son exceed 3000, but a northwestern exten- American Prairie Conference: Prairie Biodiversity sion into Saskatchewan (Hamilton 2005) (Kansas State University, Manhattan). has many of the same six endemic spe- Hamilton, K.G A. 1997a. Leafhoppers (Homoptera: cies (especially those on little bluestem, Cicadellidae) of the Yukon: dispersal and ende- Andropogon scoparius). This northern prai- mism. pp. 337-375 In Danks, H.V. and J.A. Downes rie has an admixture of 26 more widespread (Eds.), Insects of the Yukon. Biological Survey of Canada, Ottawa. northeastern prairie species and appears to be an ecotone with aspen parkland. Hamilton, K.G.A. 1997b. Short-horned bugs. In I.M. Smith (Ed.), Assessment of Species Diversity in the Mixedwood Plains Ecozone [electronic publi- References cation on CD-ROM]. Bouchard, P., K.G.A. Hamilton and T.A. Wheeler. 2002. Diversity and conservation status of prairie Hamilton, K.G.A. 1998. The species of the North endemic Auchenorrhyncha (Homoptera) in alvars American leafhoppers Ceratagallia Kirkaldy and of the Great Lakes region. Proceedings of the Aceratagallia Kirkaldy (Rhynchota: Homoptera: Entomological Society of Ontario 132 [December Cicadellidae). The Canadian Entomologist 130: 2001]: 39-56. 427-490. Cheng, S.A., J.C. Cheng, H.. Si, L.M. Yan. T.L. Chu, Hamilton, K.G.A. 1999a. Leafhoppers (Insecta: C.T. Wu, J.K. Chien and C.S. Yan. 1979. Studies Homoptera: Cicadellidae) as indicators of endan- on the migration of brown Nilaparvata gered ecosystems. pp. 103-113 In J. Loo and M. lugens Stål. Acta Entomologica Sinica 22:1-21. Gorman (Comp.), Protected Areas and the Bottom Line. Proceedings of the 1997 Conference of the Chiykowski, L.N. and R.K. Chapman. 1965. Migration Canadian Council on Ecological Areas, September of the six-spotted leafhopper Macrosteles fascifrons 14-16, 1997, Fredericton, New Brunswick. (Stål), Part 2. Migration of the six-spotted leafhop- Canadian Forest Service. (9 Nov. 2009) Research Bulletin 261: 23-45. Hamilton, K.G.A. 1999b. Short-horned bugs. in: G.G.E. Cody, W.J., D.B.O. Savile and M.J. Sarazin. 1986. Scudder and I.M. Smith (Eds.), Assessment of Systematics in Agriculture Canada at Ottawa, Species Diversity in the Montane Cordillera Ecozone. 1886-1986. Agriculture Canada Historical Series Ecological Monitoring and Assessment Network. 28. http://www.naturewatch.ca/eman/reports/publica- tions/99_montane/homopter/intro.html (19 Nov. Danks, H.V. 1979. Summary of the diversity of 2009) Canadian terrestrial arthropods. In Canada and its Insect Fauna. In: H.V. Danks (ed.), Memoirs of the Hamilton, K.G.A. 2002a. Îles-de-la-Madeleine Entomological Society of Canada 108: 240-244. (Magdalen Is.): a glacial refugium for short- horned bugs (Homoptera: Auchenorrhyncha)? Le Ghauri, M.S.K. 1983. A case of long-distance disper- Naturaliste canadien 126(1): 25-40. sal of a leafhopper. pp. 249-255 In 1st International Workshop on Leafhoppers and Planthoppers of Hamilton, K.G.A. 2002b. Homoptera (Insecta) in Economic Importance. Edited by W.J. Knight, Pacific Northwest grasslands. Part 2 - Pleistocene N.C. Pant, T.S. Robertson and M.R. Wilson. refugia and postglacial dispersal of Cicadellidae, Commonwealth Institute of Entomology, London. Delphacidae and Caliscelidae. Journal of the Entomological Society of British Columbia 99: Hamilton, K.G.A. 1982. The Insects and Arachnids 33-80. of Canada. Part 10. The Spittlebugs of Canada. Homoptera: Cercopidae. Agriculture Canada Hamilton, K.G.A. 2004a. Leafhoppers and their Publication 1740. 102 pages. relatives (Homoptera, Auchenorrhyncha) from the Canadian Great Plains. Arthropods of Canadian

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Grasslands 10: 16-24. http://www.biology.ualberta. Medler, J.T. 1962. Long-range displacement ca/bsc/pdf/grasslands10.pdf (9 Nov. 2009) of Homoptera in the central . Proceedings of the XI International Congress of Hamilton, K.G.A. 2004b. Abundant endemic bugs and Entomology 3:30-35. Canadian plains conservation. In T.A. Radenbaugh and Glenn C. Sutter, (Eds.), Managing Changing Odum, E.P. 1971. Fundamentals of Ecology, 3rd edi- Prairie Landscapes. Prairie Forum 30 (1, Spring tion. (W.B. Saunders, Philadelphia). 2005): 107-122 +6 plates. Paiero, S.M., S.A. Marshall and K.G.A. Hamilton. Hamilton, K.G.A. 2005. Bugs reveal an extensive, 2003 . New records of Hemiptera from Canada and long-lost northern tall-grass prairie. BioScience Ontario. Journal of the Entomological Society of 55(1): 49-59. Ontario 134: 115-129. Hamilton, K.G.A. 2009. Cicadas of Canada. http:// Ricketts, T.H., E. Dinerstein, D.M. Olson, C.J. Loucks, www4.agr.gc.ca/AAFC AAC/display afficher. W. Eichbaum, D. Della Sala, K. Kavanagh, P. do?id=1229021431446&lang=eng (9 Nov. 2009) Hedao, P.T. Hurley, K.M. Carney, R. Abell and S. Walters. 1999. Terrestrial Ecoregions of North Hamilton, K.G.A. [in press] Short-horned bugs America: a Conservation Assessment. Island Press, (Homoptera-Auchenorrhyncha). In: D. MacAlpine Washington, D.C. 470 pp. (Ed.), Assessment of Species Diversity in the Atlantic Maritime Ecozone. NRC Press Sauchyn, D., S. Kennedy and J. Stroich. 2004. Drought, Biodiversity Monograph Series. climate change, and the risk of desertification on the Canadian prairies. Prairie Forum 30 (1, Spring Hamilton, K.G.A., and D.W. Langor. 1987. Leafhopper 2005): 143-155. fauna of Newfoundland and Cape Breton Islands (Rhynchota: Homoptera: Cicadellidae). The Scudder, G.G.E. 1979. Present patterns in the fauna Canadian Entomologist 119: 663 695. and flora of Canada. Chapter 3 In H.V. Danks (ed.), Canada and its Insect Fauna. Memoirs of the Hamilton, K.G.A. and K. MacQuarrie. 2000. Entomological Society of Canada 108: 87-179. Leafhoppers and their relatives in P.E.I. Island Naturalist Oct.-Dec. 1999 (154): 4-6. Smith, S., I. Marshall and Ecological Stratification Working Group. 1996. A national ecological Hosie, R.C. 1969. Native trees of Canada. Queen’s framework for Canada. Agriculture and Agri-Food Printer, Ottawa. Canada, State of the Environment Directorate, Huckett, H.C. 1965. The Muscidae of northern Canada, Ottawa/Hull. Report and national map at 1:7 500 Alaska and Greenland (Diptera). Memoirs of the 000 scale. Entomological Society of Canada 42. Waloff, N. 1973. Dispersal by flight of leafhop- Küchler, A.W. 1964. Potential natural vegetation pers (Auchenorrhyncha: Homoptera). Journal of of the coterminous United States. American Applied Ecology 10(3):705-730. Geographical Society Special Publication 36. 116 pp. Maw, H.E.L., R.G. Foottit, K.G.A. Hamilton and G.G.E. Scudder. 2000. Checklist of the Hemiptera of Canada and Alaska. NRC Research Press, Ottawa. 220 pp.