Conservation status of Saint John River Valley Hardwood Forest in western New Brunswick

24 Pages·2001·12.5 MB·English

by  A Macdougall

RHODORA,
No. 47-70, 2001
Vol. 103, 913,
pp.
CONSERVATION STATUS OF SAINT JOHN RIVER
HARDWOOD NEW
VALLEY FOREST WESTERN
IN
BRUNSWICK
Andrew MacDougall
1
New
Nature Trust of Brunswick, RO. Box 603 Station A,
NB, E3B 5A6
Canada,
Fredericton,
'Current Address: Department of Botany,
V6T
University of British Columbia, Vancouver, BC, Canada, 1Z4
asmacdougall@
e-mail: sprint. ca
Hardwood (SJRHF)
abstract. Saint John River Valley Forest a re-
is
gionally threatened northern disjunct plant assemblage of the central John
St.
New
River Valley and associated tributaries of southwestern Brunswick and
Two
northeastern Maine. centuries of land clearance have reduced this as-
1%
Remaining
semblage to less than of original extent. stands, especially
its
of more mature trees, support 31 regionally rare vascular plant taxa and are
at risk due to increased cutting. Assessment of the effect of recent disturbance
SJRHF
on has been hampered by limited distributional information; past sur-
veys were wide-ranging but nonsystematic. This study describes results of a
km
SJRHF
systematic habitat-based survey for remnants across 2000 2 of
New
One
western Brunswick. hundred and twenty one stands were assessed
for the presence of rare vascular plant taxa and disturbance. Fifty-four pre-
SJRHF
viously unknown stations with one or more rare taxa were identified.
Two new
taxa were discovered for the province and one provincially extir-
pated taxon was re-located. One hundred and fifteen of 121 stands showed
46%
evidence of tree harvest. Within the last two decades, of the surveyed
Ongoing
sites had been fully or partially clearcut or converted to potato fields.
stand loss suggests that conservation measures are required to maintain rem-
nant assemblages. In situations where reserve formation not possible, oc-
is
SJRHF
currence of herbs, including rare taxa, in previously select-cut stands
may
indicates that modified low-intensity harvest strategies not be incom-
patible with their persistence.
New
Key Words: Saint John River Valley Hardwood Forest, Brunswick,
Maine, deciduous forest, rare vascular plant taxa, conservation
Hardwood (SJRHF)
Saint John River Valley Forest a
re-
is
deciduous assemblage
gionally threatened northern disjunct forest
of the central John River Valley and associated tributaries of
St.
New
southwestern Brunswick and eastern Aroostook County,
SJRHF
Maine (Figure The composition of resembles
floral
1).
New
broadleaf forests of north-central England, eastern Ontario,
and the central Lawrence River Valley of Quebec, but the
St.
47
48 Rhodora
[Vol. 103
Major
Figure concentrations of deciduous
eastern forest vascular flora
1.
(shaded) within Maine, southeastern Quebec, and the Maritime Provinces
oi'
eastern Canada. Maine and Quebec from Eastman
distributions extrapolated
McMahon
(1981) and (1990), and from Rousseau (1974), respectively.
km
assemblage from
isolated these areas by 150 or more. As-
is
sociated with the enriched calcareous soils and moderate climate
SJRHF
of the central John River Valley, has been subject
St. to
extensive land clearance since the onset of European settlement
Hardwood
in the early 1800s. Saint John River Valley Forest
1%
presently covers less than of the land base believed have
to
once supported assemblage (MacDougall and Loo
this 1998).
It
provides habitat for 31 vascular plant taxa considered rare or
New
threatened within Brunswick, Maine, the Maritime Provinc-
Gulf Lawrence
or the of region general (Gawler
es, St. in et
al.
New
1996; Hinds 1983; Brunswick Committee on Endangered
Species 1995; Pronych and Wilson Recent
1993). increased log-
ging and agricultural land clearance have led concerns regard-
to
SJRHF New
ing the persistence of Brunswick, though
in assess-
ment
of the distribution and conservation of remnant
status patch-
es has been limited by nonsystematic survey Of
past efforts. par-
SJRHF
concern
ticular are the ranges of rare vascular plant
—
Hardwood 49
MacDougall John River Forest
2001] St.
and degree which increased disturbance has af-
species, the to
SJRHF
remnants.
fected
survey
This paper presents results of a systematic habitat-based
km
SJRHF approximately 2000 2 of southwestern
stands across
for
New
The describe the distribu-
Brunswick. objectives are
to: 1)
SJRHF
vascular plant
remnant describe the rare
of stands, 2)
tion
and
composition and disturbance history of the remnants,
species
discuss the implications of these findings for future conser-
3)
management
vation efforts.
STUDY AREA
Hardwood
General John River Valley
description. Saint
Acer
assemblage dominated by sac-
deciduous
Forest a forest
is
americana
charum Marsh, Fagus grandifolia Ehrh., Fraxinus L.,
with Ostrya virginiana
and Betula ghaniensis Britton, (P.
alle
Ulmus
americana
K. Koch, Juglans cinerea L., Tilia L.,
Mill.)
secondary
americana and Tsuga canadensis (L.) Carriere as
L.,
Loo assemblage
components (MacDougall and 1998). This oc-
formation
deciduous
curs near the periphery of the eastern forest
most
described by Braun (1950) and possesses the northeasterly
vascular plant taxa
occurring concentration of southern-affinity
found along a gradient of declin-
within formation. also
this
It is
and
runs the north east
deciduous diversity that to
ing forest floral
made by absence of taxa
North America. This evident the
of
is
and
such Carya ovata Mill.) K. Koch, Dicentra canadensis,
as
(P.
Phegopteris hexagonoptera (Michx.) Fee that are characteristic
and which extend Ontario
into
of broadleaf forests to the south,
The abundance of americana, plus the
and Quebec. relative F.
such
americana, and understory species
presence of cinerea,
T.
J.
Phryma
and leptostachya distinguishes
Galearis spectabilis
as
SJRHF hardwood found northern
from other forest types in
The bark can-
Maine and Maritime Provinces [Note: butternut
the
clavigignenti-juglandacearum) has yet to seri-
ker (Sirococcus
New
though
Brunswick cinerea populations, sev-
ously affect
J.
John
possibly infected trees were observed in the central St.
eral
1997-98 Canadian Forest Service,
River Valley (K. Harrison,
in
comm.)].
pers.
John River Val-
Environmental conditions of the central St.
Hardwood with
John River Valley Forest associated
Saint is
ley.
50
Rhodora
|Vol. 103
and
the rich well-drained calcareous and moderate
soils relatively
climate
that characterize the central John River Valley and
St.
associated tributary The
valleys. extent of the calcareous
soils
New
generally defines the regional boundaries across Brunswick
and Maine (McMahon New
1990; Brunswick Department
of Nat-
New
Resources and Energy
ural
1996). In Brunswick, two edaph-
units predominate, and most
ic are the and
fertile intensively
farmed New
soils in the province (Colpitts 1995; Brunswick
et
al.
Department
of Natural Resources and Energy The
1996). Caribou
Soil Unit a finely textured and
is fast-draining glacial derived
till
from
Ordovician
argillaceous parent
material. the richer of
It is
two
the soil groups and occurs mostly to the west of the John
St.
River extending Maine. The
into Carleton Unit
Soil a
fine-
is
compact
textured
glacial derived from
Silurian calcareous
till
sandstone and found on
lower
the reaches of
is the central
St.
John
River
Valley, especially on the east side of the river between
New
Hartland and
Florenceville, Brunswick.
Topographically,
the region dissected by the Kintore
is Hills,
narrow,
a rugged, noncalcareous upland
that cuts across the
St.
John
River Valley in an east-west direction below
just the junc-
of Aroostook
ture the and John To
Rivers (Figure
St. the south
2).
of
the Kintore
Hills, the terrain is flat to gently rolling with ele-
vations generally below 200 m.
Upriver, the terrain more un-
is
m
dulating; areas below 200 occur
mostly proximity
in to the
Aroostook
and John To
St. Rivers. the east and the southeast of
the central John River
St. Valley, the regional boundaries
are
defined by noncalcareous metamorphic
or uplands
granitic
New
(Loucks
1961; Brunswick Department
of Natural Resources
and Energy
1996).
The
climate of the central St. John River Valley warmer and
is
M
M
(M
1964), a longer
frost-free
period (80 to 120 days; Hinds and
1980), annual
precipitation
mm
around 1050 (New Brunswick
Department
of Natural Re-
sources and Energy
1996).
Post-glacial The SJRHF
origins.
origins of
lie in the vege-
changes
tation occurred
that northeastern North America
in
fol-
lowing
glacial retreat approximately 13,000 YBP. Saint John Riv-
Hardwood
er Valley assumed
Forest
be
is to a relic disjunct as-
—
Hardwood
MacDougall John River Forest 51
2001] St.
Grand
Falls
Aroostook
River
Guisiguft
f)
Brook
Florence
Big Presque
ville
Stream
Isle
Meduxne-
keag River
10
km
John River Valley
Figure Study area boundaries within the central St.
2.
New
New by Brunswick Department of Natural
Brunswick, defined
of as
Resources and Energy (1996). Contour intervals are 100 m.
52 Rhodora
[Vol. 103
semblage Kellman Raup
(sensu
1980; remnant
1937), a of a pre-
viously wide-ranging
broadleaf
forest that retreated south from
Maritime
the Provinces due
to climatic change, but was
locally
maintained due
favorable
to habitat conditions. Supporting
evi-
dence comes from two
sources: tree pollen data and extrapola-
tions of past distribution based on existing herb taxa occurrence
patterns, including extirpation information.
Tree
pollen data indicate thermophilous hardwood
that
forest
was more New
previously abundant
in northern England and the
Mariti
3000
YBP
(Anderson
Green
et al. 1986; 1987; Mott 1975a, 1975b).
The
northward movement
of broadleaf was
forest driven by the
warmer
and mostly
drier climate that characterized northeastern
North America
during the early and mid-Holocenc (Davis
1976;
Davis
et 1980; Prentice Mott
al. et al. 1991). (1975a, 1975b)
New
speculated
that, at the time of peak abundance, Brunswick's
hardwood
forest resembled present-day SJRHF,
with high
levels
of
Fraxinus, Acer, Betula, Fagus, and
Ulmus. Following 3000
YBP
climatic degradation
led to a decline of broadleaf
spe-
tree
and
cies an increase in Picea spp. and Abies balsamea
(L.)
P.
Mill.
Present-day occurrence
patterns of mesic herbs Maritime
the
in
Provinces suggest many were once more
that widely
distributed.
Isolated stations of southern-affinity herbs
are scattered across
the
—
SJRHF
region most
the extensive and
is species-rich, but
sites
SJRHF
some
with elements New
occur
also northern Bruns-
in
wick's Restigouche River Valley (Cooney Hay
1832; Hinds
1896;
New
1983,1986), the lower John River
St. Valley of Brunswick
(Hinds MacDougall
1983, 1986; and
et 1998), several areas
al.
Nova
Cape
in Scotia including Breton (Fernald 1921, 1922; Nich-
1918; Pronych and Wilson
olls Robinson
1993; 1903; Zinck
many
Because
1998). broadleaf
forest herbs are notoriously poor
dispersers (Bierzychudek
1982; Cain 1998; Matlack
et al. 1994),
formation of these by
isolates long-distance migration seems
un-
likely: the distances separating
isolates are too numbers
great, the
of
taxa in these areas are too large to have been established by
low
frequency
long-distance dispersal events, and the areas are
separated by nondeciduous
forest habitat within which mesic
herbs rarely or never
establish. Instead, species migrated
likely
into the region in association with the more widely ranging
de-
ciduous forest of the mid-Holocene. As
this forest contracted.
—
Hardwood
MacDougall John River Forest 53
2001] St.
mesic herb populations persisted in local areas with rich soils,
narrow bottomlands or with calcareous parent
either alluvial sites
SJRHF
One few
Maritime Provinces with
material. area in the
Edward became
Edward
taxa Prince Island. Prince Island iso-
is
New Nova
from Brunswick and Scotia mainland be-
lated the
YBP
5000-3000
tween due ocean increase (Bousfield
to level
Many
Thomas Kranck northward-migrating
and 1975; 1972).
may Northumberland
plants not have reached the Strait area until
became submerged, though of
the intense level
after the corridor
Edward followed
conversion on Prince Island that settle-
habitat
impoverishment.
ment (Erskine 1985) could also explain floral
were
evidence suggests mesic herbs pre-
Extirpation also that
viously more prevalent. Cryptotaenia canadensis, a deciduous
species found throughout most of central and eastern North
forest
known
was from
America formerly several
(Fernald 1950), sta-
New
Brunswick and Maine but has not been seen in either
tions in
mid- 1900s (Eastman 1981; Hinds
jurisdiction since the early- to
1983). Similarly, Trillium grandiflorum (Michx.) Salisb. has not
been seen Maine since 1926 (Campbell et 1995), and an
in al.
New
Brunswick
western (H.
old report apparently exists for
Hinds, comm.). There are also reports of Betula lenta L.
pers.
(Braun 1950; Cooney 1832; Halliday 1937; Perley 1847), Car-
Michaux
pinus caroliniana Walter (Fern 1808;
Muhl.
Speck and Dexter us rubra
Perley 1847;
John
(Perley 1847; Speck and Dexter 1952) in the central St.
Mariti
ever been formally collected. Although these records could easily
common
be the result of identification errors or misapplication of
common name
names "black birch", the of Betula lenta,
(e.g.,
New
was often used to describe B. alleghaniensis in 18th century
Brunswick survey records; Lutz 1997), their occurrence plau-
is
sible due to the close proximity of their present-day northern
M
&
The evidence could
anecdotal nature of extirpation
1990). this
when from
disappeared
period these species
the
reflect, in part,
immediate
were
the region. Fertile habitats usually subject to
by Taxa were already rare the time of
clearing that at
settlers.
may have been eliminated before botanical surveys
settlement
commenced
in the mid- to late- 1800s.
New
Settlement history. The settlement of western Bruns-
54
Rhodora
(Vol. 103
wick and eastern Aroostook County by Europeans
did not begin
until the early 1800s. Before this time, the Malecite Indians oc-
cupied the John River Valley two
St. for at least millennia, using
the river and associated
tributaries as travel corridors access
to
coastal wintering areas and hunting grounds (Ganong
interior
The
1899). Malecite established few permanent settlements and
practiced agriculture on very compared
a limited basis groups
to
New
England Cronon
in central and
(e.g., 1983), thus are be-
lieved have had impact on
to
the
little forest.
In the early 9th century, large numbers of began
settlers en-
1
John
tering the central River Valley from lower John
St. the
St.
River Valley and from Maine;
central land grants along
the river
and backcountry were
in the quickly At
filled. that time, the re-
was
gion called "the garden of Maine" due
to fertile soils
its
was
(Bailey
1894). estimated that took only 50 years, ending
It
it
in the 1860s, for the area to be converted from "dark wilderness"
to a pastoral landscape (Bailey During
1894). the period of peak
which
settlement, most
lasted for of the 19th century, the area
was dominated by farms and small communities. Patches of
forest
persisted mostly woodlots may
as subject to selective cutting and
have SJRHF
served
as the only refuges
for
flora.
Following
the turn of the century, rural land abandonment be-
gan
John
in the central St. River Valley, mirroring trends ob-
served elsewhere eastern North America
in as populations
shifted
urban Many
to centers (Foster 1998; Matlack
et 1997). farms,
al.
away
from
especially the reverted back Remnant
rivers,
to forest.
SJRHF
stands survived
that the 1800s are thought have
to re-
mained
most
stable for of the 20th century. Recent increases
in
demand
the for hardwood, combined with improved
harvest
ca-
pabilities, have led to increased cutting. Given that many of the
second growth
region's have
forests not developed and
fully pos-
low
sess percentages of hardwood
tolerant
tree species, the
is
it
SJRHF
older stands supporting remnant
species most
that are
at
risk.
Early
botanical explorations and
forest
classifica-
The
tions. botanical significance of the John River Valley
St.
and was
associated
tributaries recognized soon
after settlement.
hardwood
In addition to the botanists were drawn
flora, also
to
the calcareous fens, poorly drained Thuja
occidentalis
L. forests,
and rocky
calcareous
shorelines of the region hosted numer-
that
—
Hardwood 55
MacDougall John River Forest
2001] St.
van brunetianus Fernald
ous taxa Astragalus alpinus L.
rare
[e.g.,
Carex
and Polygala senega L. along shorelines; sterilis Willd.,
&
Gray)
Candida and Valeriana uliginosa (Torr.
Salix Willd.,
swamp George Goodale, curator of
Rydb. and
fens forest].
in
eastern
botany for the Portland Society of Natural History, visited
He
Aroostook County the 860s. noted the presence of south-
in
1
and commented on the unique character of the
taxa
ern-affinity
New
(Goodale
England general 1861, 1862).
region relative to in
were
numerous botanical forays
During the next several decades,
made on both sides of the border, expanding the list of species
and
Fernald
and confirming the significance of the area (e.g.,
compiled
Wiegand Hay John Species
1910; 1883; 1929). lists
St.
New Hay
Brunswick (Fowler 1901;
1885;
during period for
this
SJRHF
found
Hay 1882, 1884) contain most of the taxa
et
al.
These have served valuable references for re-lo-
as
today.
lists
and assessing distribution
populations of rare species
cating
changes.
SJRHF
was recognized regional
The significance of also in
New
England and Maritime
the
vegetation classifications for
Though small area and disjunct in distribution,
Provinces. in
Hawes
SJRHF was by Hawley and (1912) as part of
classified
Maine,
hardwood of southern
association typical
the northern
New Hampshire, Vermont, western Massachusetts, and northern
New Loucks
York. Braun (1950) followed this classification.
recognized the distinct character of this forest
(1961) similarly
surrounding areas, distinguishing as a separate forest
relative to it
Maritime Provinces.
region for the
AND METHODS
MATERIALS
SJRHF
of potential Potential sites in
Identification sites.
New
western Brunswick were identified using a fine-scale habitat-
conducted on Geographical Information
based search procedure a
System The procedure focused on the selection of loca-
(GIS).
tions with a high probability of hosting rare vascular flora. Sites
by GIS method possessed a combination of spatially
the
identified
environmental data layers forest cover, soil fer-
referenced (e.g.,
conditions associ-
together best described the habitat
that
tility)
SJRHF on
mature deciduous stands well-
forest
with
ated rarities:
was based on
drained calcareous This habitat description
soils.
New
SJRHF Brunswick,
occurrence observations in
existing
56 Rhodora
[Vol. 103
combined
with studies in eastern North America that demonstrat-
ed a paucity of woodland herbs immature and
in heavily disturbed
deciduous
forest stands (Matlack 1994; Meier Whit-
1995;
et
al.
ney and The
Foster
1988). use of procedure
this site identification
was
necessary due
to the extensive area of the river valley (2000
km
2 and random and
the visually indiscrete distribution of ma-
)
embedded
ture stands within a landscape of farms, settlements,
and By
regenerating forest. directing ground surveys mature
to
deciduous
forest stands, large areas considered unsuitable for rare
SJRHF
vascular flora in terms of habitat bogs) or
(e.g., distur-
bance old Populus spp.-Abies balsamea were
(e.g., field
forest)
avoided. was
Site identification not conducted Maine due
in to
time constraints and the perception hardwood
that the forests of
Aroostook County had undergone more
intensive and widespread
New
disturbance than Brunswick Rooney, comm.).
in
(S. pers.
Only few SJRHF known
a scattered stations are from Aroostook
County, and
they contain just over half of the rare taxa found
in
New
Brunswick.
The GIS
method
search
for identifying potential consisted
sites
—
The
of three sequential two
steps. first steps identifying the re-
gional study area boundary and
selecting well-drained calcareous
—
employed
soil units a previously established multi-level Eco-
Land
(ELC)
logical Classification developed
for the province of
New
(New
Brunswick Brunswick
Department
of Natural Re-
sources and Energy 1996; Zelazny The ELC was
1997).
et
al.
derived using combinations of and
abiotic vegetational data layers
across a range of spatial resolutions, including fine-scale edaphic
and
topographic
habitat variables targeted by The
this study. third
step in the identification process involved
stand-level photo-in-
terpreted data describing canopy composition and age
class.
The ELC
study area boundary was defined by
the
district-level
(1:250,000)
classification delineated using geomorphological and
topographical information. This boundary
followed
the distribu-
tion of calcareous parent material within the John River Val-
St.
New
running from below Woodstock,
ley, Brunswick,
to
St.
New
Leonard, Brunswick, north of Grand The
Falls (Figure
2).
boundary
international defined western
the limit. All previously
known SJRHF
but one occurred
sites
in this district.
ELC
The
second employed
step
site-level (1:20,000) designa-
tions delineated using information on
soil fertility, soil drainage,
and
elevation, slope, and supplemented with cover
forest data.