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Earthworms (Oligochaeta: Lumbricidae and Megascolecidae) in the Canadian forests.

Authors:
  • Oligochaetology Laboratory, Kitchener, Ontario, Canada

Abstract

Canadian forests cover 43% of its landmass, which represent 10% of the world's overall forested areas and 30% of the world's boreal forests. There are eight forest regions in Canada plus grassland and tundra. Each forest region is represented by a description, map, earthworm diversity and function. Four appendices summarize: the distribution and diversity earthworms in Canadian forests according to dominant tree species and the Canadian and American soil type systems; earthworms recorded from the eight Canadian forest regions; earthworms recorded from the 10 dominant forest soils; and descriptions of the soil type profiles in Canada from which earthworms have been recorded. A map of the soil orders in Canada is presented. A table summarizes the mean values for morpho-anatomical traits characterizing the most frequent ecological categories with which earthworms are associated. The discussion considers arctic earthworm migration and climate change. Key words: Canada, Oligochaeta, Lumbricidae, Megascolecidae, forest regions, earthworms, distribution, soils, Arctic migration, climate change.
Printed in Canada*ISSN 0380-9633
MEGADRILOGICA
Volume 26, Number 12, June 2022
THE EARTHWORMS (OLIGOCHAETA: LUMBRICIDAE, MEGASCOLECIDAE)
IN THE CANADIAN FORESTS.
John Warren Reynolds
Oligochaetology Laboratory, 9-1250 Weber Street East, Kitchener, ON Canada N2A 4E1, and Research Associate,
New Brunswick Museum, Saint John, NB Canada E2K 1E5 (e-mail: john.w.reynolds1941@gmail.com)
ABSTRACT
Canadian forests cover 43% of its landmass, which represent 10% of the world's overall forested areas and
30% of the world's boreal forests. There are eight forest regions in Canada plus grassland and tundra. Each forest
region is represented by a description, map, earthworm diversity and function. Four appendices summarize: the
distribution and diversity earthworms in Canadian forests according to dominant tree species and the Canadian and
American soil type systems; earthworms recorded from the eight Canadian forest regions; earthworms recorded from
the 10 dominant forest soils; and descriptions of the soil type profiles in Canada from which earthworms have been
recorded. A map of the soil orders in Canada is presented. A table summarizes the mean values for
morpho-anatomical traits characterizing the most frequent ecological categories with which earthworms are
associated. The discussion considers arctic earthworm migration and climate change.
Key words: Canada, Oligochaeta, Lumbricidae, Megascolecidae, forest regions, earthworms, distribution, soils,
Arctic migration, climate change.
RÉSUMÉ
Les forêts canadiennes couvrent 43 % de la masse continentale du pays, ce qui représente 10 % de
l'ensemble des zones forestières mondiales et 30 % des forêts boréales à l'échelle de la planète. Il y a huit régions
forestières au Canada, auxquelles viennent s'ajouter les prairies et la toundra. Chaque région forestière comprend
une description, une carte, un inventaire de la diversité des vers de terre et leur fonction. Quatre annexes résument
la répartition et la diversité des vers de terre dans les forêts canadiennes en fonction des essences d'arbres dominantes
et des systèmes de sols canadiens et américains; les vers de terre recensés dans les huit régions forestières
canadiennes; les vers de terre recensés dans les dix sols forestiers dominants; et les descriptions des profils de types
de sols au Canada dans lesquels des vers de terre ont été recensés. Une carte des ordres de sols du Canada est
présentée. Un tableau résume les valeurs moyennes des traits morpho-anatomiques caractérisant les catégories
écologiques les plus fréquentes auxquelles les vers de terre sont associés. La discussion porte sur la migration des
vers de terre arctiques et le changement climatique.
Mots-clé: Canada, Oligochaeta, Lumbricidae, Megascolecidae, régions forestières, vers de terre, répartition, sols,
migration arctique, changement climatique.
RESUMEN
Los bosques canadienses cubren el 43 % de su masa terrestre, lo que representa el 10 % de las áreas
boscosas totales del mundo y el 30 % de los bosques boreales del mundo. Hay ocho regiones forestales en Canadá
además de pastizales y tundra. Cada región forestal está representada por una descripción, mapa, diversidad de
lombrices y función. Cuatro apéndices resumen: la distribución y diversidad de lombrices de tierra en los bosques
canadienses según las especies de árboles dominantes y los tipo de suelo canadienses y estadounidenses; lombrices
de tierra registradas en las ocho regiones forestales canadienses; lombrices de tierra registradas en los 10 suelos
forestales dominantes; y descripciones de los perfiles de tipo de suelo en Canadá a partir de los cuales se han
registrado lombrices de tierra. Se presenta un mapa con los tipos de suelo en Canadá. Una tabla resume los valores
medios de los rasgos morfo anatómicos que caracterizan las categorías ecológicas más frecuentes con las que se
asocian las lombrices. La discusión considera la migración de lombrices de tierra en el Ártico y el cambio climático.
Palabras Clave: Canadá, Oligochaeta, Lumbricidae, Megascolecidae, regiones forestales, lombrices de tierra,
distribución, suelos, migración ártica, cambio climático.
* Published on the traditional territory of the Neutral, Anishinaabeg and Haudenosaunee Peoples.
Earthworms in the Canadian Forests186
ÀÍÍÎÒÀÖÈß
Ëåñà ïîêðûâàþò 43% òåððèòîðèè Êàíàäû, ÷òî ñîñòàâëÿåò 10% îò îáùåé ïëîùàäè ëåñîâ â ìèðå è 30%
ìèðîâûõ áîðåàëüíûõ ëåñîâ. Â Êàíàäå âûäåëÿåòñÿ âîñåìü ëåñíûõ ðåãèîíîâ, à òàêæå ëóãà è òóíäðà. Äëÿ êàæäîãî
ëåñíîãî ðåãèîíà ïðåäñòàâëåíû îïèñàíèå, êàðòà, ðàçíîîáðàçèå è ôóíêöèè äîæäåâûõ ÷åðâåé. ×åòûðå ïðèëîæåíèÿ
âêëþ÷àþò: ðàñïðåäåëåíèå è ðàçíîîáðàçèå äîæäåâûõ ÷åðâåé â êàíàäñêèõ ëåñàõ â çàâèñèìîñòè îò ïðåîáëàäàþùèõ
ïîðîä äåðåâüåâ è òèïîâ ïî÷â ïî êàíàäñêîé è àìåðèêàíñêîé êëàññèôèêàöèîííîé ñèñòåìå; ñïèñêè
çàðåãèñòðèðîâàííûõ âèäîâ äîæäåâûõ ÷åðâåé â âîñüìè ëåñíûõ ðåãèîíàõ Êàíàäû; ñïèñêè çàðåãèñòðèðîâàííûõ
âèäîâ äîæäåâûõ ÷åðâåé â 10 ãîñïîäñòâóþùèõ òèïàõ ëåñíûõ ïî÷â; îïèñàíèÿ ïðîôèëåé îñíîâíûõ òèïîâ ïî÷â â
Êàíàäå, â êîòîðûõ áûëè çàðåãèñòðèðîâàíû äîæäåâûå ÷åðâè. Ïðåäñòàâëåíà êàðòà ïî÷âåííûõ ïîðÿäêîâ Êàíàäû.
 òàáëèöå ïðèâåäåíû ñðåäíèå çíà÷åíèÿ ìîðôî-àíàòîìè÷åñêèõ ïðèçíàêîâ, õàðàêòåðèçóþùèõ íàèáîëåå òèïè÷íûå
ýêîëîãè÷åñêèå êàòåãîðèè äîæäåâûõ ÷åðâåé. Îáñóæäåíèå ïîñâÿùåíî àðêòè÷åñêîé ìèãðàöèè äîæäåâûõ ÷åðâåé
è èçìåíåíèþ êëèìàòà.
Êëþ÷åâûå ñëîâà: Êàíàäà, Oligochaeta, Lumbricidae, Megascolecidae, ëåñíûå ðåãèîíû, äîæäåâûå ÷åðâè,
ðàñïðîñòðàíåíèå, ïî÷âû, àðêòè÷åñêàÿ ìèãðàöèÿ, èçìåíåíèå êëèìàòà.
INTRODUCTION
Forests are important in Canada. They cover
43% of Canada's landmass, and make a significant
contribution to the country's economy and
environmental and social well-being. On a global
basis, Canadian forests consist of 10% of the world’s
forest cover, 30% of the world's boreal forest, and 23%
world's temperate rainforest. Earthworms have the
potential to change fundamental soil properties, with
profound consequences that cascade up to include
effects on ecosystem functioning and biodiversity. The
widespread invasion of exotic earthworms into
Canada's forests could therefore have global
implications (Addison, 2009).
A forest region is defined as a major
geographic belt or zone characterized by a broad
uniformity both in physiography and in the composition
of the dominant tree species. Canada can be divided
into eight forest regions. Sometimes tundra and
grasslands are included as forest regions nine and ten,
but they are not real forests.
In North America it is generally accepted that
most indigenous earthworms did not survive the late
Wisconsonian stage of Pleistocene glaciation, and that
the majority of the earthworms now inhabiting soils in
Canada and northern regions of the US are relatively
recent introductions (Gates, 1970; Reynolds, 1994).
Consequently – with the exception of relatively small
areas where relict native earthworm populations have
survived – Canadian soils, their vegetation, and their
carbon and nutrient pools have developed in the
absence of earthworms.
CANADIAN FOREST REGIONS
There are eight major forest regions in
Canada: Acadian, Boreal (3 subtypes), Coast,
Columbian, Deciduous/Carolinian, Great Lakes-St.
Lawrence, Montane, and Subalpine (Figure 1).
Until recently, most Canadian research on
earthworms has focused on agricultural environments
where they are thought to have a generally beneficial
influence on soil structure and fertility (e.g., Tomlin
and Fox, 2003; Clapperton et al., 1997).
Biogeographical publications, largely the work of
Reynolds and his collaborators, have confirmed that
exotic earthworms were becoming widely distributed
across Canada. As early as almost 50 years ago, I
documented the presence of exotic earthworms in
forests in North America, including forest types that
occurred in Canada, e.g., Acadian (Acadienne), Boreal
(Boréale), Deciduous/Carolinian, Great Lakes-St.
Lawrence (Caduque Septentrionale), Coast and
Columbian (Côtière et Columbia), and Montane and
Subalpine (Montagnarde) (Reynolds, 1976b).
In subsequent years, and often in collaboration
with colleagues, I have continued to study the
earthworms in various Canadian Forest Regions:
Acadian Forest (Reynolds, 1975a, 1975d, 1976a, 2001;
Reynolds et al., 2015; McAlpine et al., 2022), Boreal
Forest (Reynolds, 2000a, 2000b, 1975b, 1975c; Moore
and Reynolds, 2003; Moore et al., 2009; Reynolds et
al., 2014, 2019), Deciduous/Carolinian Forest
(Reynolds, 2011a), and the Great Lakes-St. Lawrence
Forest (Reynolds, 1975b, 1976a, 1977a, 2007;
Reynolds and Mayville, 1994; Reynolds and Reynolds,
1992).
However, only recently have ecologists and
even regulatory bodies started taking a closer interest in
the distribution and activities of exotic earthworms,
especially those invading natural ecosystems.
There have been a number of other colleagues
who have surveyed earthworms in various Canadian
Forest Regions. Addison (2009) presented an excellent
summary about earthworms in forest types, but her
paper was metadata relying heavily on numerous
surveys by Reynolds and colleagues (Moore and
Reynolds, 2003; Reynolds, 1977a, 2000a, 2000b, 2001,
2002, 2003; Reynolds and Clapperton, 1996;
Reynoldsand Khan, 1999; Reynolds and Moore, 1996;
Reynolds and Reynolds, 1992).
MEGADRILOGICA 187
Figure 1. Forest regions of Canada (after Rowe, 1972; Natural Resources Canada, 2007 in Lamoureux et al., 2012).
In western Canada, studies examining
earthworms in forest regions were conducted by:
McKey-Fender and Fender (1982), Spiers et al. (1986),
McKey-Fender et al. (1994), Dymond et al. (1997),
McLean and Parkinson (1997, 2000a, 2000b), Scheu
and McLean (1993), Scheu and Parkinson (1994), and
Cameron et al. (2007).
In eastern Canada, studies examining
earthworms in forest regions not involving Reynolds
were conducted by: Bohlen et al. (2004), Whalen
(2004), Wironen and Moore (2006) and Sackett et al.
(2013).
A forest region is defined as a major
geographic belt or zone characterized by broad
uniformities both in physiography and in the
composition of the dominant tree species. Canada can
be divided into eight forest regions. Sometimes tundra
and grasslands are included as forest regions nine and
ten, but they are not real forests and not included here.
The forest descriptions have been modified from
Stanton and Bourchier (2020).
The earthworm authorities will occur only the
first time they are reported. Their ecological function
will be found in the Discussion.
1. Acadian Forest Region
Forest Description:
Closely related
to the Great Lakes-St
Lawrence Forest Region,
this region is confined to
Nova Scotia, Prince
Edward Island and a large portion of New Brunswick.
Red spruce (Picea rubens Sargent), balsam fir (Abies
balsamea (L.) Miller), yellow birch (Betula
alleghaniensis Britton) and sugar maple (Acer
saccharum Marshall) are commonly found. Black
spruce (Picea mariana (Miller) Britton, Sterns and
Poggenburg), white and grey birch (Betula papyrifera
Marshall, Betula populifolia Marshall, respectively),
red oak (Quercus rubra L.), white elm (Ulmus
americana L.), black ash (Fraxinus nigra Marshall),
beech (Fagus grandifolia Ehrhart), red maple (Acer
Earthworms in the Canadian Forests188
rubrum L.), trembling aspen (Populus tremuloides
Michaux) and balsam poplar (Populus balsamifera L.)
are also widely distributed.
Earthworm Diversity and Function:
The earthworms in the Acadian Forest Region
were presented in a paper on the Atlantic Maritime
Ecoregion, which included areas outside the Acadian
Forest Region (Reynolds, 2010a). This forest region is
found in three provinces (New Brunswick, Nova Scotia
and Prince Edward Island) and the Magdalene Islands
of Quebec. In all three provinces only introduced
European lumbricids comprise the earthworm
populations' (McAlpine and Reynolds, 2018, 2019,
2020, McAlpine et al., 2020; Reynolds, 1975a, 1975c,
1975d, 1976a, 2001, 2010b, 2014b; Reynolds et al.,
2015).
The following earthworm species were found
in forests in all four jurisdictions: Aporrectodea
trapezoides (Dugès, 1828), Aporrectodea tuberculata
(Eisen, 1874), Aporrectodea turgida (Eisen, 1873),
Dendrobaena octaedra (Savigny, 1826), Dendrodrilus
rubidus (Savigny, 1826), Lumbricus castaneus
(Savigny, 1826), and Lumbricus rubellus Hoffmeister,
1843. Aporrectodea rosea (Savigny, 1826) and
Lumbricus terrestris Linnaeus, 1758 were collected in
the Acadian Forest of Prince Edward Island and the
Magdalene Islands. In the forests of New Brunswick
and Nova Scotia, two additional species were collected:
Octolasion cyaneum (Savigny, 1826) and Octolasion
tyrtaeum (Savigny, 1826), but Dendrobaena lusitana
Graff, 1957 and Lumbricus festivus (Savigny, 1826)
were only found in the Acadian Forest of New
Brunswick. There are five species found in some of the
jurisdictions, but not in the Acadian Forests:
Allolobophora chlorotica (Savigny, 1826), Eisenia
fetida (Savigny, 1826), Eiseniella tetraedra (Savigny,
1826), Octolasion cyaneum (Savigny, 1826) and
Sparganophilus tamesis (Benham, 1892b) (= Sp. eiseni
Smith, 1895; see Rota et al., 2016). Their detailed
distributions in the Atlantic Maritime Ecozone and in
Ontario can be found in Reynolds (2010a, 2014b),
respectively.
2. Boreal/Taiga Forest Region
Forest Description:
Approximately
80 per cent of Canada's
forested land is in the
immense Boreal Forest
Region, which swings in
an arc south from the
Mackenzie River Delta and Alaskan border to northeast
British Columbia, across northern Alberta and
Saskatchewan, through Manitoba, Ontario and Québec,
terminating in northern Newfoundland on the shores of
the Labrador Sea. The northern boreal region consists
of open forest, with trees growing farther apart and
smaller in size as the forest stretches towards the
tundra, where only dwarf specimens persist.
The southern boreal region presents a denser,
closed forest which, at its southwest boundary in the
prairie provinces (Alberta, Saskatchewan and
Manitoba), gives way to a transitional zone dominated
by poplar. Known as the aspen grove, this part of the
forest thins out into open, almost treeless prairie. White
and black spruce (Picea glauca (Moench) Voss and P.
mariana (Miller) Britton, Sterns and Poggenburg,
respectively) are the principal species of the
predominantly coniferous boreal forest, but other
conifers (e.g., balsam fir (Abies balsamea (L.) Miller),
jack pine (Pinus banksiana Lambert) and tamarack
(Larix laricina (Du Roi) K. Koch)) also have a wide
distribution. There is a general mixture of broad-leaved
trees in the region, including white birch (Betula
papyrifera Marshall), balsam poplar (Populus
balsamifera L.) and the wide-ranging trembling aspen
(Populus tremuloides Michaux).
Earthworm Diversity and Function:
The earthworms in the Boreal Forest Region
were presented in numerous papers: Cameron et al.
(2007, 2015), Dymond et al. (1997), McLean and
Parkinson, 1997, 2000a, 2000b; Moore et al. (2009,
2018, 2022), Parkinson et al. (2004), Reynolds (1976b,
1977a), Reynolds and Reynolds (1992), Reynolds et al.
(2014, 2019), Scheu and McLean (1993). This forest
region is found in seven provinces (Alberta, British
Columbia, Manitoba, Newfoundland and Labrador,
Ontario, Quebec and Saskatchewan) and three
territories (Northwest, Nunavut and Yukon).
The most frequently encountered earthworm
species in the Boreal Forest are: Aporrectodea
tuberculata (7/3)1 and Dendrobaena octaedra (7/2)1
and Dendrodrilus rubidus, Lumbricus rubellus and
Lumbricus terrestris (7/1)1. The next group of species
are commonly encountered in this forest: Aporrectodea
trapezoides (6/0)1, Aporrectodea rosea, Aporrectodea
turgida and Octolasion tyrtaeum (5/0)1. There are six
species rarely found in the Boreal Forest: Aporrectodea
longa (Ude, 1885) (3/0)1, Lumbricus castaneus (3/1)1,
Arctiostrotus fontinalis McKey-Fender, 1994 (0/1)1,
Bimastos parvus (Eisen, 1874) (0/1)1, Lumbricus
festivus and Octolasion cyaneum (1/0)1.
1number of provinces/territories present in forest soils.
MEGADRILOGICA 189
There are four species found in some of the
jurisdictions, but not in the Boreal Forest:
Allolobophora chlorotica, Eisenia fetida, Eiseniella
tetraedra, and Sparganophilus tamesis. Their detailed
distributions can be found in Reynolds (2000a, 2014a,
2014b, 2015).
3. Coast Forest Region
Forest Description:
T h is fo re st
region covers the lower
seaward slopes of British
C o l u m b i a ' s C o a s t
Mountains and extends to
the coastal islands. Characteristic species are western
hemlock (Tsuga heterophylla (Rafinesque) Sargent),
Douglas fir (Pseudotsuga menziesii (Mirbel) Franco),
western red cedar (Thuja plicata Donn ex D. Don) and
Sitka spruce (Picea sitchensis (Bongard) Carrière), all
renowned for their value as timber-producing trees. By
comparison, the region's broad-leaved trees (e.g., black
cottonwood (Populus trichocarpa Torrey and Asa Gray
ex. Hooker), red alder (Alnus rubra Bongard), big-leaf
maple (Acer macrophyllum Pursh) have a limited
distribution and are of minor economic importance.
Earthworm Diversity and Function:
Since the Coast Forest Region is only found in
British Columbia in Canada, the most common
earthworm species present are: Aporrectodea
trapezoides, Aporrectodea tuberculata, Aporrectodea
turgida, Dendrobaena octaedra, Dendrodrilus rubidus,
Lumbricus rubellus, Lumbricus terrestris, Octolasion
cyaneum, Octolasion tyrtaeum, Arctiostrotus perrieri
(Benham, 1892a) and Arctiostrotus vancouverensis
McKey-Fender, 1994 (in McKey-Fender et al., 1994).
Less frequently collected species, with five or
fewer sites were Aporrectodea longa, Bimastos
lawrenceae Fender, 1994 (in McKey-Fender et al.,
1994) and Toutellus oregonensis (Smith, 1937).
There are seven earthworm species found in
British Columbia, but not in the Coast Forest soils, or
forest locations: Allo lobo phora chlor o tica ,
Aporrectodea limicola Michaelsen, 1890, Aporrectodea
longa, Aporrectodea rosea, Dendrobaena attemsi
Michaelsen, 1902, Eisenia fetida, Eiseniella tetraedra,
Lumbricus castaneus and Lumbricus festivus. Their
detailed distributions can be found in Reynolds (2015).
4. Columbia Forest Region
Forest Description:
Th is f or es t
region lies in southeast
British Columbia between
the Rockies and the
central plateau and
fingers its way through the subalpine region along river
valleys and lakes. The forest of this interior wet belt
strongly resembles that of the coast region, although
fewer species occur in the interior. Characteristic trees
are western red cedar (Thuja plicata Donn) and western
hemlock (Tsuga heterophylla (Rafinesque) Sargent).
The blue Douglas fir (Pseudotsuga menziesii var.
glauca (Mayr) Franco) is widely distributed, and in
southern parts western white pine (Pinus monticola
Douglas), western larch (Larix occidentalis Nuttall),
grand fir (Abies grandis (Douglas ex D. Don) Lindley)
and western yew (Taxus brevifolia Nuttall) are found.
Engelmann spruce (Picea engelmannii Parry) is found
in the upper Fraser Valley and occasionally at higher
elevations in the region.
Earthworm Diversity and Function:
The Columbian Forest Region is also found
only in British Columbia in Canada; this forest region
has very few reported collection sites where the
following earthworm species have been found:
Aporrectodea tuberculata, Lumbricus rubellus
Aporrectodea turgida, Octolasion tyrta eum,
Dendrobaena octaedra, Dendrodrilus rubidus, and
Lumbricus terrestris. No other earthworm species have
yet been reported from the Columbian Forest.
5. Deciduous/Carolinian Forest Region
Forest Description:
Canada's smallest
forest region, this area
borders the southeast
shore of Lake Huron and
the northern shores of
Lakes Erie and Ontario.
Despite its small size, this region contains the largest
number of native tree species of any region. Along
with the broad-leaved trees common to the Great
Lakes-St Lawrence Forest Region are found the
cucumber tree (Magnolia acuminata (Linnaeus)), tulip
tree (Liriodendron tulipifera L.), black gum (Nyssa
sylvatica Marshall), blue ash (Fraxinus quadrangulata
Earthworms in the Canadian Forests190
Michaux), sassafras (Sassafras albidum (Nuttall) Nees),
walnut/butternut (Juglans cinerea L.) and others which
are at the northern limits of their range. Conifers occur
only as a scattering of eastern white pine (Pinus strobus
L.), tamarack (Larix laricina (Du Roi) K. Koch),
eastern red cedar (Juniperus virginiana L.) and eastern
hemlock (Tsuga canadensis (L.) Carrière).
Earthworm Diversity and Function:
The Deciduous Forest Region with its
Carolinian Remnant is only found in the province of
Ontario in Canada. There are 13 species which have
been collected in this forest type: Aporrectodea longa,
Aporrectodea rosea, Aporrectodea trapezoides,
Aporrectodea tuberculata, Aporrectodea turgida,
Dendrobaena octaedra, Dendrodrilus rubidus,
Lumbricus castaneus, Lumbricus festivus, Lumbricus
rubellus, Lumbricus terrestris, Octolasion cyaneum and
Octolasion tyrtaeum.
Their detailed distributions can be found in
Reynolds (1976c, 2014a, 2014c). There are five
species found in Ontario, but not in this forest type:
Allolobophora chlorotica, Aporrectodea icterica
(Savigny, 1826) Eisenia fetida, Eiseniella tetraedra and
Sparganophilus tamesis.
6. Great Lakes-St Lawrence Forest Region
Forest Description:
Although it is
less than one-tenth the
size of the boreal forest,
th e Great La kes-St
Lawrence Forest Region
is Canada's second-largest
forest region. With the exception of a 322 km gap
where the boreal region touches the north shore of Lake
Superior, this forest stretches from southeastern
Manitoba to the Gaspé Peninsula. It is bordered to the
south by the deciduous forest region, and is a
transitional forest between the coniferous and
broad-leaved regions. Characteristic species are eastern
white pine (Pinus strobus L.), red pine (Pinus resinosa
Aiton), eastern hemlock (Tsuga canadensis (L.)
Carrière) and yellow birch (Betula alleghaniensis
Britton). Sugar and red maples (Acer saccharum
Marshall and A. rubrum L., respectively), beech
(Carpinus caroliniana Walter var. virginiana
(Marshall) Fernald), red oak (Quercus rubra L.),
basswood (Tilia americana L.) and white elm (Ulmus
americana L.) are also found, as are many boreal
species (see Moore et al., 2022).
Earthworm Diversity and Function:
Although southeastern Manitoba has a small
section of the Great Lakes-St Lawrence Forest Region,
no earthworms have been reported in Manitoba's
portion. The following earthworm species were found
in this forest type in both Ontario and Quebec:
Ap o rrec todea long a, Aporrecto de a r o sea,
Aporrectodea trapezoides, Aporrectodea tuberculata,
Aporrectodea turgida, Dendrobaena octaedra,
Dendrodrilus rubidus, Lumbricus castaneus, Lumbricus
festivus, Lumbricus rubellus, Lumbricus terrestris,
Octolasion cyaneum and Octolasion tyrtaeum.
There are seven species found in some of the
jurisdictions, but not in forest soils per se:
Allolobophora chlorotica, Bimastos beddardi
(Michaelsen, 1894), Eisenia fetida, Eisenia hortensis
Michaelsen, 1890, Eiseniella tetraedra, Satchellius
mammalis and Sparganophilus tamesis. Their detailed
distributions can be found in Reynolds (2014a, 2014c).
7. Montane Forest Region
Forest Description:
Th i s reg ion
i n c l u d es B r i t i s h
Co l um b ia 's c e nt ra l
plateau and several valley
pockets adjacent to the
Alberta boundary, areas which share a prevailing dry
climate. The characteristic tree of this region is the
blue Douglas fir (Pseudotsuga menziesii var. glauca
(Mayr) Franco), a smaller variety of the coast-region
type. Lodgepole pine (Pinus contorta Douglas var.
latifolia Englemann) and trembling aspen (Populus
tremuloides Michaux) are generally present, and white
spruce is found in cooler, shaded valley locations. In
southern parts of the region's more open forest,
ponderosa pine (Pinus ponderosa Lawson) is common.
Engelmann spruce (Picea engelmannii Parry) and
alpine fir (Abies lasiocarpa (Hooker) Lindley) from the
subalpine region, together with western white birch
(Betula papyrifera Marshall var. commutata (Regel)
Fernald), are important species of this region's northern
limits.
Earthworm Diversity and Function:
This is another forest region which is only
found in British Columbia in Canada. There are six
earthworm species reported from the Montane Forest
Region: Aporrectodea trapezoides, Aporrectodea
tuberculata, Dendrodrilus rubidus, Lumbricus rubellus,
Lumbricus terrestris and Octolasion tyrtaeum.
MEGADRILOGICA 191
There are three earthworm species found in the
Montane Forest Region, but not in the forest soil per se:
Allolobophora chlorotica, Aporrectodea turgida and
Eisenia fetida. Their detailed distributions can be
found in Reynolds (2015).
8. Subalpine Forest Region
Forest Description:
The Subalpine
F o r e s t R e g i o n
e nc o m p a ss e s t wo
vegetation zones. These
zones are quite distinct,
with one stretching along
the Pacific coast and the other lying inland in British
Columbia and Alberta. The two vegetation regions are
characterized by different plant populations, which are
influenced by the climate, nature, composition and by
soil erosion, the hydrographic network and human
activity.
Hence, along the Pacific coast, and especially
in British Columbia, we find yellow cypress
(Chamaecyparis noothatensis (D. Donn) Spach),
mountain hemlock (Tsuga mertensiana (Bongard)
Carrière), western hemlock (Tsuga heterophylla
(Rafinesque) Sargent), and fir (Abies lasiocarpa
(Hooker) Nuttall). In the inland areas of British
Columbia and Alberta, the subalpine forest is mainly
composed of Engelmann spruce (Picea engelmannii
Parry) and white spruce (Picea glauca (Moench) Voss).
Subalpine fir species dominate at altitude. The
secondary species include western larch (Larix
occidentalis Nuttall), white pine (Pinus monticola
Douglas) and limber pine (Pinus flexilis James). It
snows a lot on the Pacific coast, which protects the soil
from frost. Mountain hemlock, Pacific silver fir (Abies
amabilis Douglas ex. J. Forbes) and yellow cypress are
the main species here. In areas further from the coast,
the land freezes before the snow arrives.
Earthworm Diversity and Function:
There are very few earthworm species found
in this forest region. The following seven species are
reported from both Alberta and British Columbia
sections of this forest type: Aporrectodea tuberculata,
Aporrectodea turgida, Dendrobaena octaedra,
Dendrodrilus rubidus, Lumbricus rubellus, Lumbricus
terrestris and Octolasion tyrtaeum. Their detailed
distributions can be found in Reynolds (2015).
DISCUSSION
Although there are 26 earthworm species in
the forest soils of the Canadian Forest Regions, they are
not all performing the same function. Earthworm
ecological types were first described by Bouché (1970,
1972). He had only three forms: anéciques (anecic),
épigées, and endogées. Although more widely known
as designations by Bouché, he patterned his forms from
earlier work by Gisin (1943) who had only two forms:
épigées, and endogées. He also modelled his system
after concepts presented earlier by Wilcke (1953) and
Lee (1959) although they did not use these terms.
Bouché (1972: 475–476) constructed his system on
several factors: 1) colour or pigmentation, 2)
musculature, 3) respiration, 4) regeneration, 5)
nephropores, 6) diapause, 7) tail morphology, and 8)
tail size. His system was qualitative, not quantitative.
Recently, Bouché's classification has been quantified
from his original dataset utilizing 125 species (Table 1)
(Bottinelli et al., 2020). Based on my work, primarily
in North America, I added two more types in 1977, e.g.
corticole and limicolous. Since then others have added
a number of other types: amphibious, aquatic, arboreal,
epi-anecic, epi-endogeic, endo-anecic, geophagous,
hydrophilic, marine, ripicolous, and saproxylic. These
are primarily subdivisions of the five types I use and
may be used in some cases for aquatic oligochaetes; it
depends on whether you are a lumper or splitter!
Anecic (anécique) species are deep burrowers
(up to 2 metres); once they have completed their
burrow system they do not eat their way through the
soil as endogeic species, instead returning to the surface
to feed on soils, plant litter, duff, and to copulate
(Figure 2: 1). These species are very large, measuring
90–300 mm in length as adults. Anecic species are
strongly pigmented, commonly reddish-brown in colour
and consume large amounts of litter annually. Examples
of earthworm species in Canadian forest soils are:
Aporrectodea longa and Lumbricus terrestris.
Epigeic (épigée) species are small to medium
sized earthworms, measuring usually 1–7 cm in length
as adults. They also appear reddish-brown on the
dorsal surface and are litter and surface-dwelling
species found in the litter or in the A horizon of the soil.
Epigeic mainly feed on plant litter and dwell on the soil
surface or in litter layers (Figure 2: 3). As they
consume humus or soil, their castings neutralize the soil
and – by aggregation of soil particles – improve water
infiltration and percolation. Examples of earthworm
species in Canadian forest soils are Bimastos
lawrenceae, Dendrobaena octaedra, Lumbricus
castaneus, Lumbricus festivus, Arctiostrotus perrieri
and Arctiostrotus vancouverensis.
Earthworms in the Canadian Forests192
Figure 2. The common locations of the earthworm ecological types: 1 = anecic/anécique; 2 = endogeic/endogée; 3 =
epigeic/épigée; 4 = corticole/corticole; and 5 = limicolous/limicoles (modified from Reynolds, 1977b).
Table 1. Summary of the mean values for morpho-anatomical traits characterizing the most frequent ecological
categories studied by Bouché (1972) (after Bottinelli et al., 2020).
Morpho- Epigeic Endogeic Anecic Epi-anecic
anatomical traits
Length (mm) 62 79 349 143
Diameter (mm) 2 3 9 6
Weight (mg) 518 751 1,235 3,054
Pigmentation (%) 100 0 100 100
Skin colour red (86%) pink (61%) grey (100%) grey (55%)
Anterior-posterior 100 0 100 100
gradient (%)
Dorso-ventral 95 0 84 100
gradient (%)
Flattening index1No (43%) No (45%) Clitellum-Tail (47%) Clitellum-Tail (45%)
Tail (29%) Clitellum (29%) Tail (47%) Tail (23%)
1 see Bottinelli et al. (2020) for discussion of flattening index.
Endogeic (endogée) species – medium sized
worms (usually measuring 20–120 mm in length as
adults), living in horizontal burrows as soil feeders
(Figure 2: 2). They are shallow, horizontal burrowers
with no preferential orientation, often refilling burrows
with casts. Endogeic species frequently are
unpigmented, but some species may appear pinkish,
whitish, green, yellowish-brown, or gray-blue. They
live and feed in the mineral soil horizons getting their
energy from minerals and carbohydrates (litter) found
MEGADRILOGICA 193
there. These species can tunnel through the soil, often
to depths of almost 50 cm. Examples of earthworm
species in Canadian forest soils are: Aporrectodea
limicola, Ap. rosea, Aporrectodea trapezoides, Ap.
tuberculata, Ap. turgida, Octolasion cyaneum, O.
tyrtaeum and Toutellus oregonensis.
Some endogeic species may be collected from
habitats more commonly supporting epigeic species
frequenting the soil surface during favourable weather
conditions (periods of increased precipitation and
cooler temperatures) but burrowing back into the soil
during periods of dry and warmer weather, or to
aestivate or hibernate, e.g., Lumbricus rubellus
(Reynolds, 2018).
Corticole species frequently small sized
worms (usually measuring<100 mm in length as adults)
are those which live under the bark of fallen trees, frass
(the sawdust-like material) between the bark and the
tree-wood cambium layer (Figure 2: 4). Many of these
species are found in the litter adjacent to the fallen
trees. Habitat usage by corticole species (e.g., Bimastos
beddardi [Michaelsen, 1894], B. heimburgeri [Smith,
1928], B. longicinctus, B. parvus, B. tumidus [Eisen,
1874] and B. zeteki [Smith and Gittens, 1915]) depends
on their geographical location, and can also be
influenced by the presence of other earthworm species
(e.g., Dendrodrilus rubidus) (Èernosvitov and Evans,
1947; Gerard, 1964; Reynolds,1977b). For example, in
areas where one or more Bimastos spp. are found, they
usually are the dominant corticole species perhaps
influencing Dendrodrilus rubidus individuals to move
into habitat more commonly occupied by epigeic
species.” Bimastos lawrenceae may be a corticole
species, but so few individuals from a limited area are
known that it is not possible to define fully its
ecological role at this time.
Limicolous (limicole) species are mud
dwellers, living in very wet habitats that include the
saturated soils along the banks of streams, ponds, lakes,
wetlands, flood plains, as well as saturated tree-wood
(Figure 2: 5), and moist litter covering the soil / muddy
surfaces in these areas; species are also often collected
from the sediments in truly aquatic habitats, and from
depths approaching one metre. Most Sparganophilus
species (family Sparganophilidae) are considered to be
limicolous (Reynolds, 1980, 2001, 2008). Eiseniella
tetraedra and Allolobophora chlorotica (Savigny,1826)
(family Lumbricidae) are commonly collected from
moist to saturated soils, mud, and from lentic and lotic
habitats. Several species in yet other families are also
discovered, live, in aquatic and semi-aquatic habitats,
although likely there only temporarily (as waifs,
probably washed in during precipitation events, or
stranded when water levels have receded).
Sparganophilus species are unpigmented; Eiseniella
tetraedra is yellowish to yellow-brown in colour. These
are not generally found in forest soils. Their habitat
usage depends on geographical location and the other
earthworm species present.
A summary of the earthworms in the forest
regions can be found in Appendix I.
Canada and the northern United States were
under ice during the Wisconsin glaciation that ended
approximately 11,000 years ago. Therefore, the
majority of earthworms present in these regions prior to
the last glacial period were eradicated (Reynolds, 1994;
Reynolds et al., 1974). Earthworms have been slow to
recolonize these areas since the glaciers retreated, so
northern forests have developed in the absence of
earthworms (Reynolds, 2018). Recent decades of
increased global travel and commerce has led to the
introduction of European and Asian earthworms to
these previously earthworm-free areas as well as to
areas, where the results of surveys for earthworms were
limited to native species only (Reynolds, 1976b, 2002,
2003, 2004; Addison, 2009; Reynolds et al., 2019).
The forest floor, also known as the litter layer
or O horizon, is composed of decaying plant material.
Forest soils gain new carbon mainly through the life
cycle of plants. Carbon dioxide enters leaves through
the stoma and is utilized in photosynthesis and then
stored in the plant until it dies. Plant organic matter
then falls to the forest floor where it is incorporated on
the litter layer or incorporated in lower horizons when
the plant roots dies (Janzen, 2004). Only when carbon
reaches the A or B horizons does it become stabilized.
Earthworms play a role in this process, though their
exact function depends on where they live, what food
resources are present, and what the earthworms chose
to consume (Serniak, 2017). The earthworms in the
Canadian forest regions are predominantly invasive
European species which often decrease the mass and
thickness of the forest floor, or in some cases can cause
the litter layer to completely disappear (Wironen and
Moore, 2006).
There is a difference in the leaf litter in the
forest, and earthworms have shown a preference for
different leaf species. Initial studies in leaf litter
breakdown were conducted by Edwards and Heath
(1963) and Heath et al. (1966). They found the
disappearance rates of leaf discs in fine mesh bags in
woodland soil to be: elm>ash=lime>oak = beech
sometimes the rates of oak and beech were similar, but
oak always disappeared first. In subsequent studies
using several other leaf species, colleagues and I were
Earthworms in the Canadian Forests194
able to expand the preference list as follows: Robinia
(locust) >> Alnus (alder) = Populus (poplar) > Prunus
(cherry) = Salix (willow) = Ulmus (elm) = Acer
(maple) = Liriodendron (tulip poplar) > Fraxinus (ash)
= Tilia (basswood) = Gleditsia (locust) = Betula
(birch) > Quercus (oak) = Fagus (beech) > Picea
(spruce) = Pinus (pine) = Abies (fir) = Thuja (cedar) =
Tsuga (hemlock) = Pseudotsuga (Douglas fir) = Larix
(larch/tamarack) (Reynolds and McBrayer, unpublished
data, 1968); Reynolds, 1972; Reynolds and Jordan,
1975). I have termed this sequence the leaf palatability
index since the earthworm preference is the same as the
natural leaf disappearance order. This is not surprising
since the greater amount of lignins and tannins in the
oak and beech leaves and conifer needles are more
difficult for earthworms to digest.
Soil temperature is important for earthworm
development with the optimum being 12–25EC for
most species. Reynolds and Jordan (1975) noted that
most soil pH levels associated with earthworm habitats
ranged from 4.0 to 8.1 (H2O) (Reynolds and Jordan,
1975). This was recently supported by Ruiz et al.
(2021):
"Favourable soil moisture and mechanical conditions
dominate the global distribution of earthworms. Additional
constraints such as permafrost soil and subzero MAT
preclude earthworm activity in large parts of the world.
Despite evidence for soil acidity limitations (soil pH < 4.5),
the global earthworm distribution was not overly sensitive to
low values of soil pH. The primary mechanism that shapes
earthworm occurrence appears to be driven by soil physical
(hydromechanical) conditions; determined by soil moisture
and earthworm physiological limitations in unfrozen soils."
The distribution of soil orders in Canada is
shown in Figure 3.
The results in Appendix II should come as no
surprise, considering 15.8 % of the land mass contains
podzolic soils (= Spodosols). Therefore, it would be
suspected that earthworms would be recorded primarily
in these soils. It should be pointed out that 20.7% of
the land mass is not considered forest or forest soils
(marked * on Figure 3). Also, cryosolic soils (=
Gelisols) which represent 40% of the land mass are in
areas which are for the most part devoid of earthworms.
If you add these two groups together it represents
approximately 61% of the land mass, so that podzolic
soils comprise about 62.5% of the forested land mass
which could be inhabited by earthworms. The second
largest area where earthworms have been recorded are
the brunisolic order (= Inceptisols) which represents
approximately 31% of the forested land mass. The
remaining 6.5% of the forested land mass where
earthworms are reported is divided between Gleysols
and Organic (= Histosols), Luvisols (= Alfisols), and
Regosols (= Entisols) soils.
A summary of earthworm species recorded
from the various forest soils in Canada is presented in
Appendix III. Soil type profiles in Canada from which
earthworms have been recorded are summarized in
Appendix IV.
I used to think that all earthworms were good,
and that there were no negative aspects to their
activities in the soil. In recent decades their spread as
invasive species and the effect of climate change have
caused me to rethink my original position. I have often
thought of myself as the antithesis of Johnny
Appleseed, travelling the world taking samples
randomly, instead of spreading apple seeds randomly
everywhere he went (Hillis, 1917; Means, 2011).
The question that has been on on the minds of
many scientists is – what effect is climate change going
to have on earthworms in the Canadian Forest Regions?
Physical properties of soils have been altered
by the invasive pheretimoid earthworms and their
casting layer creates a thermal refuge (Görres et al.,
2019). Ali and Naaz (2013) have used earthworms as
biomarkers for assessing the environmental impact in
soils.
Climate change can have a significant effect
on organisms above and below the soil surface in
terrestrial ecosystems (Singh et al., 2019). Many
ecological factors can affect earthworm population
densities, biomass and the species complex.
Undoubtedly, the obvious and most frequently cited
factors include soil moisture, soil temperature and soil
acidity each of which potentially can act as a
complete limiting factor. Other factors, such as soil
depth and texture, nutrient and food supply (vegetation
species), physiographic features (physiographic
position, slope, aspect, elevation) and soil colour can
interact with the above factors and influence soil
conditions; a preliminary model reflecting these
interactions was published nearly 50 years ago
(Reynolds and Jordan, 1975). We suggested that soil
moisture tension was more important than the
percentage of moisture in the soil, which seems to have
been ignored in most subsequent studies, e.g., Diehl
and Williams (1992) and Bessolitsyna (2012).
Earthworm communities ebb and flow with the
changing precipitation patterns (Tondoh, 2006;
Eisenhauer et al., 2019), but if the moisture is not
available to the earthworms, this pattern may not be
sustainable. Therefore, soil moisture tension gives a
better indication of earthworm's ability to reproduce
and feed in a given habitat (Reynolds, 2021).
MEGADRILOGICA 195
Figure 3. Soil Order map of Canada with Percent of Land Mass (Canadian Society of Soil Science, 2020).
Biological invasions can have strong impacts
on biodiversity as well as ecosystem functioning and
introduced below ground organisms (e.g., earthworms)
may have strong effects. The impacts of introduced, or
invading earthworms on plant diversity and community
composition in Canadian forests can be significant
(Craven et al., 2017).
I have noticed a change in the earthworm
diversity in North America during the past 50 years. In
the mid to late 1960's, the Oriental pheretimoid species
(Amynthas, Metaphire, Pithemera and Polypheretima
spp.) were limited in natural habitats to the southeastern
United States, particularly south of Tennessee
(Reynolds, 1978, 2011b). A change in climate permits
a rapid increase in their range due to their
parthenogenetic reproduction. In the past 50 years,
they have spread into the midwestern and the
northeastern American soils (Reynolds, 2011c, 2010c,
respectively). It was not until recently that I recorded
the first populations of these earthworms in Canada
(Reynolds, 2014a) and then again in 2021 (Reynolds
and McTavish, 2021) and 2022 (McAlpine et al.,
2022). I may not live to see it happen, but as the soils
in Canada warm, and if precipitation in the form of
increased rain and vegetation diversifies, one day
earthworms will become a major component of the soil
fauna in the Canadian far north.
Development of recreational and industrial
activities are rapidly expanding in the boreal forests of
western Canada. It has been suggested that this activity
is facilitating the introduction and spread of non-native
species such as exotic European earthworms,
particularly Dendrobaena octaedra, Dendrodrilus
rubidus and Lumbricus rubellus (Cameron et al., 2007;
Reynolds, 2015; Moore et al., 2022). Since earth-
worms cannot migrate very far on their own, Cameron
et al. (2007) suggested four mechanisms for their
introduction: 1) bait cast-offs, 2) dispersal via vehicles,
Earthworms in the Canadian Forests196
3) dispersal via vertebrate predators, and 4) dispersal
via waterways. Their research indicates that the first
two mechanisms are the most likely. My experience,
particularly in the United States, has shown that river
flooding is a definite means of dispersal. In the
Canadian far north where the rivers, streams and lakes
flow into the Arctic region, this is a definite possibility.
Saint Mary's University environmental
scientist Dr. Erin K. Cameron found that virtually all
the earthworms in one study area in Alberta belonged
to a species that eats leaf litter but doesn't burrow into
the soil. In a 2015 study, she modelled the worms'
effects over time. "Forest-floor carbon is reduced by
between 50 and 94%, mostly in the first 40 years, and
that carbon is released into the atmosphere" (Cameron
et al., 2015). In an earlier study, Cameron et al. (2007)
determined the worms' range would increase from 9%
of northeastern Alberta to half of the region by 2049.
Today, the Arctic is a treeless plain with only
sparse tundra vegetation, such as grasses, sedges and a
few flowering plants (Reynolds, 2020). In contrast, the
Russian sediment cores contained pollen from trees
such as larch (Larix spp.), spruce (Picea spp.), fir
(Abies spp.) and hemlock (Tsuga spp.) (Geraskina et
al., 2021). This shows that boreal forests, which today
end hundreds of miles farther south and west in Russia
and at the Arctic Circle in Alaska and Canada, once
reached all the way to the Arctic Ocean, across much of
Arctic Russia and Arctic North America. Changes in
Arctic vegetation can have important implications for
trophic interactions and ecosystem functioning leading
to climate feedbacks. Arctic plant communities and
species are generally sensitive to warming, but trends
over a period of time are heterogeneous and complex
(Bjorkman et al., 2018).
The latest evidence of drastic Arctic warming
came when scientists recorded extreme summer melt
rates across the Greenland Ice Sheet. In early August
2020, Canada's last remaining ice shelf, in the territory
of Nunavut, collapsed into the sea. Parts of Arctic
Siberia and Svalbard, a group of Norwegian islands in
the Arctic Ocean, reached record-shattering high
temperatures 38EC (100EF) in the summer of 2020
(Brigham-Grette and Petsch, 2020).
Earthworms must adapt to the temperature
conditions generally prevailing in the soil. Reynolds
(1973) reported the optimum soil temperature for
earthworm development for several species:
Aporrectodea rosea 12EC, Aporrectodea turgida 12EC,
Dendrodrilus rubidus 18–20EC, Eisenia fetida 25EC,
Lumbricus rubellus 15–18EC and Octolasion cyaneum
15EC.
Soil can hold heat, or cold, better than air
does. Soil temperatures at any given depth are
inherently insulated by the soils both above and below
that depth; surface and subsurface temperatures are also
insulated by vegetation, snow, and other natural and
anthropomorphic ground cover. Changes in soil
temperatures fluctuate less with increasing depth. While
ambient or air temperature can exhibit change as great
as +/- 50°F (10°C) in 24 hours, the change in soil
temperature may take one to several days to fluctuate
even a couple of degrees.
In the Swedish Boreal Forest, Jungqvist et al.
(2014) found that although air temperature could also
be changing more rapidly than soil temperatures in this
catchment on an annual scale, the largest change was
projected to occur in the top soil, with differences
between the top/lower layers responses being most
pronounced in late summer and early autumn. This
showed that the projected effects of climate change on
soil temperature in snow dominated regions are
complex, and general assumptions of future soil
temperature responses to climate change based on air
temperature alone are inadequate and should be avoided
in boreal regions.
Therefore, climate change will have the
greatest immediate affect on epigeic species which live
in the litter layer and surface soil, e.g., Arctiostrotus
fontinalis, Ar. perrieri, Ar. vancouverensis, Bimastos
lawrenceae, Dendrobaena octaedra, Dendrodrilus
rubidus, Lumbricus castaneus, and L. festivus. The
endogeic species which live in the surface soil will be
less affected by the early stages of climate change, e.g.,
Aporrectodea limicola, Ap. rosea, Ap. trapezoides, Ap.
tuberculata, Ap. turgida, Lumbricus rubellus,
Octolasion cyaneum and O. tyrtaeum. The anecic
species, Aporrectodea longa and Lumbricus terrestris,
may be able to resist the effects of climate change the
longest, as they burrow deeper in the soil profile and
come to the surface just to feed and copulate.
One species in particular found in western
Canada, Arctiostrotus perrieri, will definitely be
affected by climate change, "These taxa are extremely
intolerant of heat and will decompose quickly in a room
that is comfortably warm to humans." (Fender and
McKey-Fender, 1990: 364).
Grant (1955), using three different species,
determined their upper lethal temperatures to be 27.7EC
MEGADRILOGICA 197
[Eisenia fetida], 24.9°C [Amynthas hupeiensis
(Michaelsen, 1895)] and 24.7°C [Aporrectodea
turgida]) following acclimatization at 22EC.
Acclimatization produces an average gain in heat
tolerance of 0.3EC per 1EC increase in conditioning
temperature.
The presence of parthenogenetic morphs, and
wide plasticity in terms of soil and habitat preferences
in several of these species means that they are excellent
invaders, particularly in subtropical, tropical and even
temperate regions (Chang et al., 2017; Brown et al.,
2006).
Arctic Earthworm Migration and Climate Change
The question is whether the invasion of
earthworms in the North will effect the release of
carbon in the soil, or increase the concentration of
atmospheric carbon dioxide (CO2) in the soil
(sequestration). However, it is difficult to determine at
present, and the results may often contradict each other.
As an example, Zhang et al. (2013) and Coleman et al.
(2017) showed how earthworms contribute to net
carbon sequestration (a natural or artificial process by
which carbon dioxide is removed from the atmosphere
and held in solid or liquid form) in soil.
Earthworms were often found to stimulate CO2
emission, especially in short-term experiments, but they
have also been reported to enhance carbon stabilization
in soil aggregates in some longer-term experiments
(Coleman et al., 2017). Nevertheless, more
experimental data support the view that earthworms
reduce carbon sequestration, due to the fact that CO2
emission is easier to detect than carbon stabilization.
As a result, a recent meta-analysis study concluded that
earthworm presence will increase CO2 emissions from
soil by 33 % (Lubbers et al., 2013). In contrast, Zhang
et al. (2013) found that earthworms could facilitate net
carbon sequestration through unequal amplification of
carbon stabilization compared with carbon
mineralization. Zhang et al. proposed that neither an
increase in CO2 emission nor that in stabilized carbon
would entirely reflect the earthworms' contributions to
net carbon sequestration; that is, the impacts of
earthworms on the two coupled processes of carbon
mineralization and carbon stabilization should be
studied simultaneously. They found that, firstly,
although earthworms accelerate carbon mineralization,
the total amount of CO2 that can potentially escape
from the soil with earthworms differs little from soil
containing no earthworms because the capacities of
carbon mineralization of earthworms and soil
microbiota are similar. Most previously published
studies did not note this, and thus, were likely to
conclude that earthworms decrease carbon
sequestration only because CO2 emission was often
enhanced by earthworms (Lavelle, 1997; Liski et al.,
2003). Secondly, an increase in carbon mineralization
(Cmin) and carbon stabilization (Csta) may be a natural
consequence of an increased pool of activated carbon
which can impact plant activity. The pool size of the
activated carbon (Cact) and its allocation pattern into
carbon mineralization and carbon stabilization then
determines the net carbon sequestration. Thus, Zhang
et al. introduced the new concept of sequestration
quotient (SQ, Csta/Cact) to quantify the earthworms'
impact on the balance of carbon mineralization and
carbon stabilization. Their study revealed that the
presence of earthworms is more likely to create a
carbon sink, as the carbon stabilized by earthworms
outweighs that converted to CO2 during carbon
mineralization, i.e., SQ values are higher in soil with
earthworms.
Earthworms play an essential part in
determining the greenhouse gas balance of soils
worldwide, and their influence is expected to grow over
the next decades. They are thought to stimulate carbon
sequestration in soil aggregates, but also to increase
emissions of the main greenhouse gases CO2 and
nitrous oxide (N20). Therefore, it remains highly
controversial whether earthworms predominantly affect
soils by acting as a net source of, or sink for greenhouse
gases. Lubbers et al. (2013) provided a quantitative
review of the overall effect of greenhouse gas
emissions from soils increased by earthworms.
Another recent study (Blume-Werry et al.,
2020) indicated that invasive earthworms unlock arctic
plant nitrogen. Arctic plant growth generally has
limited nitrogen due to low temperatures and slow soil
microbial processes. Their study illustrated that arctic
plant-soil N-cycling was constrained by lack of
earthworms and their activities. Earthworm activity
also increased either the height or number of floral
shoots, while enhancing fine root production and
vegetation greenness. The effect of earthworms
suggested that human spreading of earthworms may
lead to substantial changes in the structure and function
of Arctic ecosystems. The authors reported the
earthworms only as Aporrectodea sp. and Lumbricus
sp. Since they cite Reynolds (2000a), it may be
assumed they referred to Ap. tuberculata and L.
rubellus or L. terrestris.
Earthworms in the Canadian Forests198
Another factor which is receiving more
attention due to global climate change is wildfires,
which have become more frequent and intense world
wide. This is presenting an acute problem for forested
countries, and northern Canada in particular. Forest
ecosystems are decreasing rapidly, which causes an
irreparable loss of biodiversity. This situation may
cause a permanent loss of some species and animal
communities. Even if recovery is possible, it may take
a long time to recover. There are competing views that
wildfires increase biodiversity (Geraskina et al., 2021).
Currently, vegetation in the Canadian north is sparse
compared to that present in the south. If the widespread
forest fires of recent years continue as the climate
changes, the spread of earthworms into the northern
forest regions may be delayed.
A recent report has shown that earthworms are
bioindicators of soil health (Alves et al., 2022). The
use of biological indicators, such as earthworms, to
assess the health of soil has grown because they allow
an integrated assessment of the terrestrial ecosystem's
functioning.
The Canadian Arctic hasn't been this warm for
three million years; geoscientists have great concern
about what is going on in the Arctic and the effect it
will have on the rest of the world. It has taken humans
only 200 years to completely reverse the trajectory
begun 50 million years ago and return the planet to CO2
levels not experienced for millions of years. Scientists
project that the Arctic will be completely ice-free in
summer within the next two decades, e.g., by 2040
(Brigham-Grette and Petsch, 2020).
New data recently released (Statistics Canada,
2022) showed that the population of the Canadian
North is growing. The total Canadian population has
been growing at a rate of 5%, but on average the North
is growing faster. According to information collected
in May 2016, the three territories in the Canadian North
are growing at an average rate faster than the rest of
Canada, with Nunavut leading the way at 12 percent.
From 2016–2021 the Yukon had a growth rate of
12.1%, while the Northwest Territories had a growth
rate of -1.7%.
As temperatures in northern Canada rise, there
will be vegetational changes, as well as an increase in
the human population and tourism. Since earthworms
do not migrate on their own, these activities will
contribute to the introduction of earthworm species into
the northern Canadian forests. It is my belief that by
2050, the frequency and diversity of earthworms in the
Canadian Arctic regions, i.e., those north of 60E
latitude – Northwest Territories, Nunavut and Yukon –
will be considerably greater than it is today.
ACKNOWLEDGEMENTS
I wish to thank W.M. Reynolds (Oligo-
chaetology Laboratory, Kitchener), Dr. Frederick W.
Kutz (formerly of the US EPA, Washington, DC) and
Mark J. Wetzel (Illinois Natural History Survey, Prairie
Research Institute at the University of Illinois Urbana-
Champaign) for reviewing the manuscript, and for their
comments and suggestions. The author also wishes to
thank Dr. Catalina C. de Mischis, Universidad Nacional
de Córdoba (Argentina), Dr. Jean-Marc Gagnon,
Canadian Museum of Nature (Ottawa, Ontario), and
Anna P. Geraskina (Àííà Ï. Ãåðàñüêèíà), Russian
Academy of Science (Moscow) for checking my
translations of the abstracts and key words.
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MEGADRILOGICA 207
APPENDIX I
Summary of Earthworms in Canadian Forests.
Earthworm Forest Dominant tree Soil Type Soil Type
(Ecological type) Region Species Canadian System American System
LUMBRICIDAE
Aporrectodea Coast Tsuga heterophylla Humo-Ferric Podzol Haplorhods
limicola
(endogeic)
Aporrectodea Acadian Acer saccharum, Tsuga canadensis Humo-Ferric Podzol Haplorhods
longa Boreal Betula papyrifera, Populus tremuloides Melanic Brunisol Hapludolls
(anecic) Coast Pseudotsuga menziesii, Populus tremuloides Humo-Ferric Podzol Haplorhods
Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Luvisol Hapludalfs
Aporrectodea Acadian Picea mariana, Betula papyrifera Humo-Ferric Podzol Haplorhods
rosea Ulmus americana
(endogeic) Boreal Betula papyrifera, Populus tremuloides Melanic Brunisol Hapludolls
Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
Coast Pseudotsuga menziesii, Tsuga heterophylla Humo-Ferric Podzol Haplorhods
Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Luvisol Hapludalfs
Great Lakes-St. Lawrence Alnus rugosa Brunisol Inceptisols
Great Lakes-St. Lawrence Fagus grandifolia, Acer rubrum Humic Gleysol Aquaolls
Great Lakes-St. Lawrence Acer rubrum, Fagus grandifolia Dystric Brunisol Dystrochrepts
Aporrectodea Acadian Abies balsamea, Betula papyrifera Humo-Ferric Podzol Haplorhods
trapezoides Acadian Acer saccharum, Betula alleghaniensis Orthic Podzol Cryorthods
(endogeic) Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
Boreal Populus tremuloides, Salix nigra Gray Brown Podzol Udalfs
Coast Alnus rubra, Pseudotsuga menziesii Dystric Brunisol Dystrochrept
Coast Pseudotsuga menziesii, Tsuga heterophylla Humo-Ferric Podzol Haplorhods
Coast Acer macrophyllum, Pseudotsuga menziesii Humo-Ferric Podzol Haplorhods
Columbia Pseudotsuga menziesii, Betula papyrifera Eutric Brunisol Eutrochrepts
Deciduous Plantanus occidentalis, Sassafras albidum Orthic Luvisol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Great Lake-St. Lawrence Abies balsamea, Betula alleghaniensis Humo-Ferric Podzol Haplorhods
Aporrectodea Acadian Pinus strobus, Picea rubens Humo-Ferric Podzol Haplorhods
tuberculata Acadian Abies balsamea, Betula papyrifera Ferro-Humic Podzol Cryorthods
(endogeic) Acadian Abies balsamea, Betula papyrifera Humo-Ferric Podzol Haplorhods
Acadian Acer saccharum, Tsuga canadensis Humo-Ferric Podzol Haplorhods
Acadian Acer saccharum, Tsuga canadensis Gray Brown Podzol Hapludalfs
Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
Boreal Picea glauca, Abies balsamea Orthic Regosol Udorthents
Boreal Betula papyrifera, Populus tremuloides Humo-Ferric Podzol Haplorhods
Boreal Picea glauca, Picea mariana Turbic Cryosol Turbels
Coast Pseudotsuga menziesii, Tsuga heterophylla Humo-Ferric Podzol Haplorhods
Coast Alnus rubra Fibrisol Fibrists
Columbian Thuja plicata, Tsuga heterophylla Humo-Ferric Podzol Haplorhods
Columbian Pseudotsuga menziesii, Eutric Brunisol Eutrochrepts
Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Great Lakes-St. Lawrence Fagus grandifolia, Acer rubrum Humic Gleysol Aquaolls
Great Lakes-St. Lawrence Acer rubrum, Fagus grandifolia Dystric Brunisol Dystrochrepts
Great Lake-St. Lawrence Picea glauca, Abies balsamea Humo-Ferric Podzol Haplorhods
Great Lake-St. Lawrence Picea glauca, Abies balsamea Dystric Brunisol Dystrochrepts
Montane Abies lasiocarpa, Pseudotsuga menziesii, Humo-Ferric Podzol Haplorhods
Picea glauca
Subalpine Picea englemannii, Abies lasiocarpa Ferro-Humic Podzol Cryorthods
Earthworms in the Canadian Forests208
Summary of Earthworms in Canadian Forests (continued).
Earthworm Forest Dominant tree Soil Type Soil Type
(Ecological type) Region Species Canadian System American System
Aporrectodea Acadian Acer saccharum, Betula alleghaniensis Orthic Podzol Cryorthods
turgida Acadian Acer saccharinum, Fraxinus pennsylvanica Orthic Podzol Cryorthods
(endogeic) Acadian Abies balsamea, Betula papyrifera Ferro-Humic Podzol Cryorthods
Acadian Abies balsamea, Betula papyrifera Orthic Gleysol Typic Cyaquepts
Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
Boreal Picea glauca, Abies balsamea Orthic Regosol Udorthents
Boreal Betula papyrifera, Populus tremuloides Humo-Ferric Podzol Haplorhods
Boreal Acer saccharum, Tilia americana Eutric Brunisol Eutrochrepts
Coast Alnus rubra Ferro-Humic Podzol Cryorthods
Coast Sphagnum bog Fibrisol Fibrists
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Deciduous Plantanus occidentalis, Sassafras albidum Orthic Luvisol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Great Lakes-St. Lawrence Alnus rugosa Brunisol Inceptisols
Great Lakes-St. Lawrence Acer saccharum, Betula alleghaniensis Humo-Ferric Podzol Haplorhods
Great Lakes-St. Lawrence Fagus grandifolia, Acer rubrum Dystric Brunisol Dystrochrepts
Great Lake-St. Lawrence Picea glauca, Abies balsamea Humo-Ferric Podzol Haplorhods
Montane Pseudotsuga menziesii, Populus tremuloides Humo-Ferric Podzol Haplorhods
Subalpine Picea englemannii, Abies lasiocarpa Ferro-Humic Podzol Cryorthods
Bimastos Coast Tsuga heterophylla Humo-Ferric Podzol Haplorhods
lawrenceae
(corticole-epigeic)
Dendrobaena Acadian Acer saccharum, Betula papyrifera Orthic Podzol Cryorthods
octaedra Acadian Acer saccharum, Tsuga canadensis Humo-Ferric Podzol Haplorhods
(epigeic) Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
Boreal Abies balsamea, Betula tremuloides Gray Luvisol Boralfs
Boreal Betula papyrifera, Populus tremuloides Humo-Ferric Podzol Haplorhods
Boreal Abies balsamea, Betula tremuloides Gray Luvisol Boralfs
Boreal Betula glandulosa, Populus balsamifera Melanic Brunisol Hapludolls
Coast Alnus rubra Ferro-Humic Podzol Cryorthods
Coast Tsuga heterophylla Ferro-Humic Podzol Cryorthods
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Great Lakes-St. Lawrence Acer saccharum, Betula alleghaniensis Humo-Ferric Podzol Haplorhods
Great Lakes-St. Lawrence Fagus grandifolia, Acer rubrum Dystric Brunisol Dystrochrepts
Great Lake-St. Lawrence Picea glauca, Abies balsamea Dystric Brunisol Dystrochrepts
Montane Populus tremuloides, P. balsamifera, Gray Luvisol Boralfs
Montane Pinus contorta, Abies glauca, Eutric Brunisol Cryochrepts
Populus tremuloides
Montane Pinus contorta, Abies lasiocarpa, Gray Luvisol Boralfs
Picea glauca
Montane Abies lasiocarpa, Pseudotsuga menzeii, Humo-Ferric Podzol Haplorhods
Picea glauca
Subalpine Picea englemannii, Abies lasiocarpa Ferro-Humic Podzol Cryorthods
Dendrodrilus Acadian Acer saccharum, Betula alleghaniensis Orthic Podzol Cryorthods
rubidus Acadian Acer saccharinum, Fraxinus pennsylvanica Orthic Podzol Cryorthods
(corticole-epigeic) Acadian Abies balsamea, Betula papyrifera Orthic Gleysol Typic Cryaquepts
Acadian Abies balsamea, Betula papyrifera Humo-Ferric Podzol Haplorhods
Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
Boreal Abies balsamea, Betula tremuloides Gray Luvisol Boralfs
Boreal Populus tremuloides, P. balsamifera, Gray Luvisol Boralfs
Picea glauca
Boreal Abies balsamea, Betula tremuloides Gray Luvisol Boralfs
Coast Tsuga heterophylla, Pseudotsuga menziesii, Humo-Ferric Podzol Haplorhods
Thuja plicata
Coast Tsuga heterophylla Ferro-Humic Podzol Humic Cryorthods
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
MEGADRILOGICA 209
Summary of Earthworms in Canadian Forests (continued).
Earthworm Forest Dominant tree Soil Type Soil Type
(Ecological type) Region Species Canadian System American System
Dendrodrilus Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
rubidus Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Great Lakes-St. Lawrence Acer saccharum, Betula alleghaniensis Humo-Ferric Podzol Haplorhods
Great Lake-St. Lawrence Picea glauca, Abies balsamea Dystric Brunisol Dystrochrepts
Montane Abies lasiocarpa, Pseudotsuga menzeii, Humo-Ferric Podzol Haplorhods
Picea glauca
Subalpine Picea englemannii, Abies lasiocarpa Ferro-Humic Podzol Cryorthods
Subalpine Picea engelmannii, Picea glauca Ferro-Humic Podzol Cryorthods
Lumbricus Acadian Abies balsamea, Betula papyrifera Orthic Gleysol Typic Cryaquepts
castaneus Acadian Acer saccharum, Tsuga canadensis Humo-Ferric Podzol Haplorhods
(epigeic) Boreal Acer saccharum, Tilia americana Eutric Brunisol Eutrochrepts
Boreal Acer saccharum, Betula alleghaniensis Humo-Ferric Podzol Haplorhods
Coast Alnus rubra Ferro-Humic Podzol Cryorthods
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Great Lakes-St. Lawrence Acer saccharum, Betula alleghaniensis Humo-Ferric Podzol Haplorhods
Lumbricus Acadian Acer saccharum, Tsuga canadensis Humo-Ferric Podzol Haplorhods
festivus Boreal Picea glauca, Betula papyrifera Humic Regosol Entisols
(epigeic) Boreal Acer saccharum, Betula alleghaniensis Humo-Ferric Podzol Haplorhods
Coast Alnus rubra Fibrisol Fibrists
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Great Lakes-St. Lawrence Acer saccharum, Fagus grandifolia Gray Brown Luvisol Hapludalfs
Great Lakes-St. Lawrence Acer saccharum, Betula alleghaniensis Melanic Brunisol Hapludolls
Lumbricus Acadian Acer saccharum, Fagus grandifolia Orthic Podzol Cryorthods
rubellus Acadian Acer saccharinum, Fraxinus pennsylvanica Gleyed Humic Podzol Cryohumods
(epi-endogeic) Acadian Abies balsamea, Betula papyrifera Ferro-Humic Podzol Cryorthods
Acadian Abies balsamea, Betula papyrifera Orthic Gleysol Typic Cryaquepts
Acadian Abies balsamea, Betula papyrifera Humo-Ferric Podzol Haplorhods
Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
Boreal Abies balsamea, Betula tremuloides Gray Luvisol Boralfs
Coast Pseudotsuga menziesii, Tsuga heterophylla Humo-Ferric Podzol Haplorhods
Coast Tsuga heterophylla Ferro-Humic Podzol Cryorthods
Coast Alnus rubra Humo-Ferric Podzol Haplorhods
Columbia Thuja plicata, Tsuga heterophylla Humo-Ferric Podzol Haplorhods
Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Great Lakes-St. Lawrence Alnus rugosa Brunisol Inceptisols
Great Lakes-St. Lawrence Acer rubrum, Fagus grandifolia Dystric Brunisol Dystrochrepts
Great Lake-St. Lawrence Picea glauca, Abies balsamea Humo-Ferric Podzol Haplorhods
Montane Picea contorta, P. glauca, Populus tremuloides Gray Luvisol Boralfs
Subalpine Picea engelmannii, Picea glauca Ferro-Humic Podzol Cryorthods
Lumbricus Acadian Acer saccharum, Tsuga canadensis Humo-Ferric Podzol Haplorhods
terrestris Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
(anecic) Boreal Abies balsamea, Betula tremuloides Gray Luvisol Boralfs
Coast Pseudotsuga menziesii Humo-Ferric Podzol Haplorhods
Coast Tsuga heterophylla Ferro-Humic Podzol Cryorthods
Coast Alnus rubra Ferro-Humic Podzol Cryorthods
Columbia Thuja plicata, Tsuga heterophylla Humo-Ferric Podzol Haplorhods
Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Great Lakes-St. Lawrence Acer rubrum, Fagus grandifolia Dystric Brunisols Dystrochrepts
Great Lake-St. Lawrence Picea glauca, Abies balsamea Humo-Ferric Podzol Haplorhods
Montane Populus tremuloides, Populus balsamifera Gray Luvisol Boralfs
Earthworms in the Canadian Forests210
Summary of Earthworms in Canadian Forests (concluded).
Earthworm Forest Dominant tree Soil Type Soil Type
(Ecological type) Region Species Canadian System American System
Octolasion Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
cyaneum Coast Pseudotsuga menziesii Humo-Ferric Podzol Haplorhods
(endogeic) Great Lake-St. Lawrence Acer saccharum, Tilia americana Humo-Ferric Podzol Haplorhods
Great Lake-St. Lawrence Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Octolasion Acadian Acer saccharinum, Fraxinus pennsylvanica Humo-Ferric Podzol Haplorhods
tyrtaeum Acadian Acer saccharum, Tsuga canadensis Humo-Ferric Podzol Haplorhods
(endogeic) Boreal Abies balsamea, Betula papyrifera Brunisol Inceptisols
Boreal Abies balsamea, Betula tremuloides Gray Luvisol Boralfs
Coast Alnus rubra, Pseudotsuga menziesii Humo-Ferric Podzol Haplorhods
Columbian Thuja plicata, Tsuga heterophylla Ferro-Humic Podzol Humic Haplorthods
Deciduous Plantanus occidentalis, Sassafras albidum Luvisols and Gleysol Hapludalfs
Deciduous Liriodendron tulipifera, Magnolia acuminata Gleysol Aquents
Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
Great Lakes-St. Lawrence Alnus rugosa Brunisol Inceptisols
Great Lakes-St. Lawrence Picea glauca, Abies balsamea Dystric Brunisol Dystrochrepts
Montane Populus tremuloides, Populus balsamifera Gray Luvisol Boralfs
Subalpine Picea englemannii, Abies lasiocarpa Ferro-Humic Podzol Cryorthods
MEGASCOLECIDAE
Amynthas agrestis Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
(epi-endogeic)
Amynthas Acadian Acer saccharum, Fraxinus pennsylvanica Humo-Ferric Podzol Haplorhods
hilgendorfi Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
(epi-endogeic)
Amynthas Acadian Acer saccharum, Fraxinus pennsylvanica Humo-Ferric Podzol Haplorhods
tokioensis Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
(epi-endogeic)
Arctiostrotus Boreal Salix pulchra, Betula glandulosa Organic Cryosol Gleic Histosols
fontinalis
(epi-endogeic)
Arctiostrotus Coast Pseudotsuga menziesii, Tsuga heterophylla Dystric Brunisol Dystrochrepts
perrieri Coast Thuja plicata, Tsuga heterophylla Ferro-Humic Podzol Humic Haplorthods
(epigeic) Coast Alnus rubra, Pseudotsuga menziesii Ferro-Humic Podzol Humic Haplorthods
Coast Acer macrophyllum Ferro-Humic Podzol Humic Haplorthods
Coast Thuja plicata, Tsuga heterophylla Fibrisol Fibrists
Arctiostrotus Coast Tsuga heterophylla, Abies amabilis Humo-Ferric Podzol Haplorthods
vanouverensis Coast Thuja plicata, Tsuga heterophylla Dystric Brunisol Dystrochrepts
(epigeic) Thuja plicata, Tsuga heterophylla Ferro-Humic Podzol Humic Haplorthods
Pithemera bicincta Deciduous Acer saccharum, Fagus grandifolia Gray Brown Podzol Udalfs
(epigeic)
Toutellus Coast Pseudotsuga menziesii Humo-Ferric Podzol Haplorthods
orgonensis Coast Thuja plicata Ferro-Humic Podzol Humic Haplorthods
(endogeic)
Sources: Addison (2009); Battigelli (2000); Cameron et al. (2007); Dymond et al. (1997); Eisenhauer et al. (2007); McAlpine and Reynolds (2018,
2019, 2020); McKey-Fender et al. (1994); McLean and Parkinson (1997); Moore and Reynolds (2003); Moore et al. (2009, 2018, 2022), Panesar et
al. (2000); Reynolds (1975a-d, 1976a,b, 1977a), Reynolds and McTavish (2021), Reynolds and Reynolds (1992), Reynolds et al. (2014, 2015, 2019),
Welke and Parkinson (2003); Whalen (2004), Wironen and Moore (2006).
MEGADRILOGICA 211
APPENDIX II
Summary of the earthworm species in the various forest regions of Canada.
Earthworm Forest Regions
__________________________________________________________________________
species Acadian Boreal Coast Columbian Deciduous Great Lakes- Montane Subalpine
(Carolinian) St. Lawrence
Lumbricidae
Aporrectodea limicola - - !- - - - -
Aporrectodea longa !-! ! -!- -
Aporrectodea rosea ! ! ! -! ! - -
Aporrectodea trapezoides ! ! ! ! ! - - -
Aporrectodea tuberculata ! ! ! ! ! ! ! !
Aporrectodea turgida ! ! ! -! ! ! !
Bimastos lawrenceae - - !- - - - -
Bimastos parvus -!- - - - - -
Dendrobaena lusitana !- - - - - - -
Dendrobaena octaedra ! ! ! -! ! ! !
Dendrodrilus rubidus ! ! ! -! ! ! !
Lumbricus castaneus ! ! ! -! ! - -
Lumbricus festivus ! ! ! -! ! - -
Lumbricus rubellus ! ! ! ! ! ! ! !
Lumbricus terrestris ! ! ! ! ! ! ! -
Octolasion cyaneum -! ! - - !- -
Octolasion tyrtaeum ! ! ! ! ! ! ! !
Megascolecidae
Amynthas agrestis - - - - !- - -
Amynthas hilgendorfi !- - - !- - -
Amynthas minimus !- - - - - - -
Amynthas tokioensis !- - - !- - -
Arctiostrotus fontinalis -!- - - - - -
Arctiostrotus perrieri - - !- - - - -
Arctiostrotus vancouverensis - - !- - - - -
Pithemera bicincta - - - - !- - -
Toutellus oregonensis - - !- - - - -
Additional species not considered to be present in Canadian forest soils: Lumbricidae – Allolobophora chlorotica, Aporrectodea
bowcrowensis, Aporrectodea icterica, Bimastos beddardi, Dendrobaena attemsi, Eisenia fetida, Eiseniella tetraedra, Satchellius
mammalis, Megascolecidae – Amynthas minimus, and Sparganophilidae – Sparganophilus tamesis.
Earthworms in the Canadian Forests212
APPENDIX III
Summary of earthworm species recorded from the various forest soils in Canada.
Earthworm Forest Soils
species
Ferric Humic Brown Dystric Melanic Eutric Orthic Humics Organic Gray/Orthic
Podzols Podzols Podzols Brunisols Brunisols Brunisols Gleysols Regosols Cryosols Luvisols
Lumbricidae
Aporrectodea limicola !- - - - - - - - -
Aporrectodea longa !-!-!- - - - !
Aporrectodea rosea ! ! -! ! - - - - !
Aporrectodea trapezoides !-! ! - - !- - !
Aporrectodea tuberculata ! ! ! ! -! ! ! ! -
Aporrectodea turgida ! ! -!- - - ! ! !
Bimastos lawrenceae !- - - - - - - - -
Bimastos parvus - - - - - - - - - !
Dendrobaena lusitana !- - - - - - - - -
Dendrobaena octaedra ! ! -! ! ! ! - - !
Dendrodrilus rubidus ! ! ! ! - - !- - !
Lumbricus castaneus ! ! ! -! ! ! - - !
Lumbricus festivus !-!-! ! -!-!
Lumbricus rubellus ! ! ! ! ! -!- - !
Lumbricus terrestris ! ! ! ! ! -!- - !
Octolasion cyaneum !-!-!- - - -
Octolasion tyrtaeum ! ! ! -!-!- - !
Megascolecidae
Amynthas agrestis - - - - - - !- - -
Amynthas hilgendorfi - - - - - - !- - -
Amynthas minimus - - - - - - - - -!
Amynthas tokioensis - - - - - - !- - -
Arctiostrotus fontinalis - - - - - - - - !-
Arctiostrotus perrieri ! ! -!- - - - - -
Arctiostrotus vancouverensis ! ! -!- - - - - -
Pithemera bicincta - - - - - - ! - - -
Toutellus oregonensis ! ! - - - - - - - -
APPENDIX IV
SOIL TYPE PROFILES FROM WHICH EARTHWORMS HAVE BEEN RECORDED
(Soil Classification Working Group, 1998)
Cryosolic Order (= Gelisols in the American System)
These soils have permafrost (permanently frozen material) within one metre of the surface
(2 m if the soil is strongly cryoturbated; i.e., disturbed by frost action). As permafrost is
a barrier to roots and water, the active layer (seasonally thawed material) above it may
become a saturated, semifluid material in spring. Commonly the permafrost layer near
the surface contains abundant ice. Melting of ice and frozen materials, resulting from
disturbance of the surface vegetation (boreal forest or tundra), may cause slumping of the
soil and disruption of roads, pipelines and buildings. Cryosolic soils, occupying about
3,672,000 km2 (about 40%) of Canada's land area, are dominant in much of the Yukon,
Northwest Territories and Nunavut and occur in northern areas of all but the Atlantic
provinces (excluding Labrador). Turbic Cryosols have a patterned surface (hummocks,
stone nets, etc.) and mixed horizons or other evidence of cryoturbation. Static Cryosols
lack marked evidence of cryoturbation; they are associated with sandy or gravelly materials. Organic Cryosols are
composed pre dominantly of organic materials (e.g., peat). Because organic material acts as an insulator, Organic
Cryosols occur farther south than the boundary of continuous permafrost.
MEGADRILOGICA 213
Organic Order (= Histosols in the American System)
These soils are composed predominantly of organic matter in the upper half metre (more
than 30% organic matter by weight) and do not have permafrost near the surface. They
are the major soils of peatlands (e.g., swamp, bog, fen). Most organic soils develop by
the accumulation of plant materials from species that grow well in areas usually saturated
with water. Some organic soils are composed largely of plant materials deposited in
lakes; others, mainly of forest leaf litter on rocky slopes in areas of high rainfall. Organic
soils cover almost 374,000 km2 (4.1%) of Canada's land area: large areas occur in
Manitoba, Ontario and northern Alberta, smaller areas in other provinces and territories.
Organic soils are subdivided into 4 great groups. Fibrisols, common in Canada, consist predominantly of
relatively undecomposed organic material with clearly visible plant fragments; resistant fibres account for over 40% by
volume. Most soils derived from Sphagnum mosses are Fibrisols. Mesisols are more highly decomposed and contain
less fibrous material than Fibrisols (10–40% by volume). Humisols consist mainly of humified organic materials and
may contain up to 10% fibre by volume. Folisols consist mainly of thick deposits of forest litter overlying bedrock,
fractured bedrock or unconsolidated material. They occur commonly in wet mountainous areas of coastal British
Columbia.
Podzolic Order (= Spodosols in the American System)
These acid soils have a B horizon containing accumulations of amorphous materials
composed of humified organic matter associated with aluminum and iron. They develop
most commonly in sandy materials in areas of cold, humid climate under forest or shrub
vegetation. Water moving downward through the relatively porous material leaches out
basic elements (e.g., calcium), and acidic conditions develop. Soluble organic substances
formed by decomposition of the forest litter attack soil minerals in surface horizons, and
much of the iron and aluminum released combines with this organic material. When the
proportion of aluminum and iron to organic matter reaches a critical level, the organic
complex becomes insoluble and is deposited in the B horizon. Dissolved aluminum and
iron may also move downward in inorganic forms and be deposited as aluminum-silicon
complexes and iron oxides. An Ae (light grey, strongly leached) horizon usually overlies
the Podzolic B horizon.
Podzolic soils occupy about 1,429,000 km2 (15.6%) of Canada's land area and
are dominant in vast areas of the humid Appalachian and Canadian Shield regions and in
the humid coastal region of British Columbia. They are divided among 3 great groups on the basis of the kind of
Podzolic B horizon. Humic Podzols have a dark B horizon with a low iron content. They occur mainly in wet sites
under humid climates and are much less common than other Podzolic soils.
Ferro-Humic Podzols have a dark reddish-brown or black B horizon containing
at least 5% organic carbon and appreciable amounts (often 2% or more) of aluminum and
iron in organic complexes. They occur commonly in the more humid parts of the area
of Podzolic soils; e.g., coastal British Columbia and parts of Newfoundland and southern
Quebec. In Labrador along the Churchill River valley Ferro-Humic Podzols comprise
about 36% of soils. Humo-Ferric Podzols, the most common Podzolic soils in Canada,
have a reddish-brown B horizon containing less than 5% organic carbon associated with
aluminum and iron complexes.
Gleysolic Order (= Histosols in the American System)
These soils are periodically or permanently saturated with water and depleted of oxygen.
Earthworms in the Canadian Forests214
They occur commonly in shallow depressions and level areas of subhumid and humid climate in association with other
classes of soil on slopes and hills. After snowmelt or heavy rains, depressions in the landscape may be flooded. If
flooding occurs when the soil temperature is above approximately 5 °C, microbial activity results in depletion of oxygen
within a few days. Under such conditions, oxidized soil components (e.g., nitrate, ferric oxide) are reduced. Depletion
of ferric oxide removes the brownish colour common to many soils, leaving them grey. As the soil dries and oxygen
re-enters, the reduced iron may be oxidized locally to bright yellow-brown spots (mottles). Thus, Gleysolic soils are
usually identified by their poor drainage and drab grey colour, sometimes accompanied by brown mottles. Gleysolic
soils cover about 117,000 km2 (1.3%) of Canada's land area.
Three great groups of Gleysolic soils are defined. Humic Gleysols have a dark A horizon enriched in organic
matter. Gleysols lack such a horizon. Luvic Gleysols have a leached (Ae) horizon underlain by a B horizon in which
the clay has accumulated; they may have a dark surface horizon.
Luvisolic Order (= Alfisols in the American System)
These soils have eluvial horizons from which clay has been leached after snowmelt or
heavy rains and illuvial horizons in which clay has been deposited; these horizons are
designated Ae and Bt, respectively. In saline or calcareous materials, clay translocation
is preceded by leaching of salts and carbonates. Luvisolic soils occur typically in forested
areas of subhumid to humid climate where the parent materials contain appreciable clay.
Luvisolic soils cover about 809,000 km2 (8.8%) of Canada's land area. Large areas of
Luvisolic soils occur in the central to northern Interior Plains; smaller areas in all regions
south of the permafrost zone.
The two great groups of Luvisolic soils are distinguished mainly on the basis of
soil temperature. Gray Brown Luvisols have a dark Ah horizon in which organic matter
has been mixed with the mineral material (commonly by earthworm activity), a brown,
often platy eluvial horizon (Ae) and an illuvial horizon (Bt) in which blocky structure is
common. Their mean annual soil temperature is 8 °C or higher. The major area of Gray
Brown Luvisols is found in the southern part of the Great Lakes-St Lawrence Lowlands. Gray Luvisols have eluvial
and illuvial horizons and may have an Ah horizon if the mean annual soil temperature is below 8 °C. Vast areas of Gray
Luvisols in the Boreal Forest Zone of the Interior Plains have thick, light grey eluvial horizons underlying the forest litter
and thick Bt horizons with clay coating the surface of aggregates.
Brunisolic Order (= Inceptisols in the American System)
This order includes all soils that have developed B horizons but do not meet the
requirements of any of the orders described previously. Many Brunisolic soils have
brownish B horizons without much evidence of clay accumulation, as in Luvisolic soils, or
of amorphous materials, as in Podzolic soils. With time and stable environmental
conditions, some Brunisolic soils will evolve to Luvisolic soils; others, to Podzolic soils.
Covering almost 790,000 km2 (8.6%) of Canada's land area, Brunisolic soils occur in
association with other soils in all regions south of the permafrost zone.
Four great groups are distinguished on the basis of organic matter enrichment in
the A horizon and acidity. Melanic Brunisols have an Ah horizon at least 10 cm thick and
a pH above 5.5 (H20). They occur commonly in southern Ontario and Quebec. Eutric
Brunisols have the same basic properties as Melanic Brunisols, except that the Ah horizon,
if any, is less than 10 cm thick. Sombric Brunisols have an Ah horizon at least 10 cm thick,
and are acid and their pH is below 5.5 (H20). Dystric Brunisols are acidic and do not have
an Ah horizon 10 cm thick.
MEGADRILOGICA 215
Regosolic Order (= Entisols in the American System)
These soils are too weakly developed to meet the limits of any other order. The absence
or weak development of genetic horizons may result from a lack of time for development
or from instability of materials. The properties of Regosolic soils are essentially those
of the parent material. Two great groups are defined. Regosols consist essentially of C
horizons. Humic Regosols have an Ah horizon at least 10 cm thick. Regosolic soils
cover about 73,000 km2 (0.8%) of Canada's land area.
ÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏ
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Seven species in four genera of lumbricid earthworms are recorded from the 2,832 ha Caledonia Gorge Protected Natural Area (CG PNA), New Brunswick, Canada. Six of the species are considered European introductions. We consider Bimastos (Dendrodrilus) rubidus, recorded at four of 15 sites surveyed in the CG PNA, as native to Maritime Canada. Non-native Aporrectodea tuberculata and Lumbricus rubellus are the most widespread earthworm species in the CG PNA. Earthworms within the CG PNA appeared to be most frequent in bottomland, roadside old field habitat, and the riparian zone of permanent and ephemeral flowing waters. Although more intensive earthworm collection in the CG PNA will likely reveal additional non-native species, further sampling should focus on hardwood dominated hilltops and upper slopes to gain a better understanding of the distribution and abundance of putative native B. rubidus in the CG PNA. RÉSUMÉ Sept espèces de quatre genres de vers de terre lumbricidés ont été recensées dans la zone naturelle protégée de la gorge Caledonia (ZNP GC), au Nouveau-Brunswick (Canada), un secteur d'une superficie de 2832 ha. Six des espèces semblent avoir été introduites d'Europe. Nous considérons que le Bimastos (Dendrodrilus) rubidus, recensé dans quatre des 15 sites étudiés dans la ZNP GC, est originaire des Maritimes. L'Aporrectodea tuberculata et le Lumbricus rubellus, non indigènes, sont les espèces les plus répandues de la ZNP GC. Les vers de terre observés dans cette zone semblaient davantage se concentrer dans les terrains en contre-bas, les anciens champs en bordure des routes et l'écotone riverain de cours d'eau permanents et intermittents. Une collecte plus poussée de vers de terre dans la ZNP GC révélerait probablement d'autres espèces non indigènes, mais cela nécessiterait d'autres échantillonnages sur les sommets de collines et les hauts de pentes à dominance de feuillus pour mieux comprendre la répartition et l'abondance du B. rubidus qu'on suppose indigène dans la ZNP GC. Mots clés: Bimastos rubidus, gorge Caledonia zone naturelle protégée, Nouveau-Brunswick, Oligochaeta, Lumbricidae, vers de terre, répartition, espèce envahissante. RESUMEN Se registraron siete especies incluídas en cuatro géneros de gusanos lumbricidos de 2,832 ha del Desfiladero de Caledonia Área Natural Protegida (CG PNA), Nuevo Brunswick, Canadá. Seis de las especies son introducciones europeas. Consideramos Bimastos (Dendrodrilus) rubidus, registrados en cuatro de 15 sitios en el CG PNA, como natural de Canadá Marítimo. El no natural Aporrectodea tuberculata y Lumbricus rubellus son las especies de gusano más extendidas en el CG PNA. Los gusanos dentro del CG PNA parecieron ser los más frecuentes en tierras bajas, borde del camino viejo, hábitat de campaña, y la zona ribereña de cuerpos de agua sueltos permanentes y efímeros. Aunque la colección de gusano más intensiva en el CG PNA revele probablemente especies no nativas adicionales, mas adelante debería concentrarse la atención en cimas dominadas por madera dura y cuestas superiores para obtener un mejor entendimiento de la distribución y la abundancia del supuesto nativo B. rubidus en el CG PNA.
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