Losses of native plant species from Worcester, Massachusetts

25 Pages·2002·11.7 MB·English

by  R I Bertin

RHODORA,
Vol. 104. No. 920, 325-349, 2002
pp.
FROM
LOSSES OF NATIVE PLANT
SPECIES
WORCESTER, MASSACHUSETTS
RoBiiRT L Bhrtin
MA
Biology Deparlmcnl, Holy Cross College, Worcester, 01610
e-mail: [email protected]
ABsrRACT. recorded the extant vascular flora of Worcester, Massachu-
I
seven years of work beeinninu 1994 and obtained
setts in field in historical
A
records from herbarium specimens and the published literature. detailed
vascular llora of the City was published elsewhere. This paper updates the
llora with information from an important and previously overlooked collec-
tion of specimens, and examines the apparent historic losses of native species
18%
in relation to habitat and taxonomy. Overall species losses were about
among
the past century. Losses were particularly high species associated
in
with aquatic habitats, bogs, and calcareous or circumneutral terrestrial habi-
many
suuuest that the of these reflects extensive alteration of
tats. first
I
bodies of water thrt)ugh sillalion. chemical pollution, cutrophication, and
may
stream channelization. Losses in the remaining two liabitat types rcdect
combined
the initial rarity of such habitats within the City with habitat de-
struction. Losses were especially high in several families, including the Or-
chidaceae, Ophioglossaceae, Caryophyllaceae, Menyanthaceae, Lentibulari-
aceac, and Lamiaceac. High losses of aquatic and bog species have been
among
noted in other areas, and high losses orchids appear to be nearly
A
universal. combination of chancin<z land use, habitat fraementation. sue-
cessional changes, species introductions, and climate changes are likely to
cause further species losses the decades ahead.
in
Key
Words: species loss, biodiversity, habitat destruction. Worcester, or-
chids, flora
common many human
Despite knovvdedge
the that activities
decrease biological diversity, such changes are only occasionally
documented and even comnionly subjected
in the literature, less
any formal analysis. Documentation and analysis of species
to
manage
losses are, however, critical to efforts to for biological
and minimize
diversity future species losses.
to
Vascular plants probably one of the groups most suited to
ai"e
the evaluation of species losses. In temperate areas, at least, they
are relatively well sttidied. In the eastern United States, recen-
suses have advantage of published records from the
titken floristic
from
1800s or early 1900s for a variety of study areas ranging
individual pk^ts (Curtis 1959) and single nature pieserves or areas
of equivalent size (Deane 1896: Pease 191 to towns, cities, and
1),
326 Rhodora
|Vol. 104
Owen
counties (Darlington 1853; Hollick and Britton 1879;
1888).
Repeated censuses of particular areas can provide various data,
numbers Such
including of species and of species
lost rate loss.
data also permit evaluation of losses in relation to life history
Many
and
attributes, habitat type, taxoncMiiic affiliation. studies
of species loss report overall losses, but attempt further anal-
little
ysis. Notable exceptions include the evaluation of species losses
on (Robinson
in relatic^n to ecological attributes Statcn Island et
(Wiegmann
and Wisconsin
1994) 2001), relation
al. in et al. in
and taxonomy Massachusetts (Drayton and Primack
to habitat in
and growth form, and taxonomy
1996), in relation to habitat, in
Singapore (Turner
1994).
et al.
Evaluation of losses areas differing geography and
in in size,
and subjected to different intensities and kinds of disturbances
We
be
are likely to particularly valuable. are currently
ill-
how
equipped to say the characteristics of the lost flora differ at
how
the levels of a nature preserve, a town, a county, and a state;
sensitive rates of species loss are to the size of the area sampled;
how
and different types of disturbances urbanization, agri-
(e.g.,
Only
culture, recreational use) influence the kinds of species
lost.
we
after analysis of a variety of sites will be able to answer these
The
one
questions. present study step in this direction. ex-
is It
amines chaiines in the vascular flora of Worcester, Massachusetts,
New
one of the largest England cities, over a period of approx-
imately 100 years. focused especially on species losses regard
in
I
taxonomy
and
to habitat affiliation.
MATHRIALS AND METHODS
The
Description of the study area. City of Worcester
lies in
south-central Worcester County, Massachusetts, covering an area
9740
of ha. falls largely within drainage of the Blackstone
Tt tlie
River, which flows to Narragansett Bay, though a small area of
northern Worcester in the drainage of the Nashua and Merri-
is
mack The
Rivers. City along an ill-defined north-south es-
lies
m
{—
carpment that separates lower land 100 elevation) to the east
and south froni higher land (-^300 m) to the west and north. The
bedrock consists largely of highly metamorphosed rocks of
Si-
and Devonian The bedrock covered by most
lurian age.
in
is till
areas, with smaller areas occupied by glacial outwash.
—
20021 Bertin Losses of Native Plant Species 327
Perhaps 300 Indians occupied the area of Worcester prior to
European Permanent European began
settlement
colonization. in
the early 1700s, and a major increase in population occurred in
(Anonymous The
the middle 1800s 1879). original forested land-
way
scape gave to agriculture, which then decreased over the past
commercial, and devel-
century. Intensive industrial, residential
opment began 1800s and continues Today,
in the to the present.
Worcester consists of an urban core, with large buildings, exten-
sive paved areas, and occasional landscaped grounds and vacant
Fingers of intensive development extend from the core along
lots.
major roads towards the edges of the City. Surrounding the areas
of intensive development are extensive residential neighborhoods,
most of which contain scattered parks and undeveloped land.
on west
Closest to the City's perimeter, especially the side, are
undeveloped mostly
larger areas of land, forested.
Historical records of the flora. used a combination of her-
I
document
barium records and published reports to the historical
One
native flora of the City. important collection housed in
is
Hadwen Herbarium Clark University (cuw). Most of these
at
specimens were between 1920 and 1955 by group of
collected a
Mary
Dodge,
botanists active the Worcester region, including
in
Norman
Burton Gates, W. H. Hodge, David Potter, George Pride,
A
Woodward, Burton N. Gates, and Winifred C. Gates. second
P.
important collection includes specimens of the Worcester Natural
History Society (unofficially abbreviated wnhs), housed the
at
Ecotarium Worcester. These were collected in the late 1800s
in
Norman
and early 1900s by a variety of collectors, including
P.
Woodward, Katherine Fish, Mary C. Dodge, and G. E, Stone.
1.
These specimens were not cited the Worcester flora (Bertin
in
New
was unaware
2000) because of existence. species
their
I
from documented
this collection are therefore in this publication.
Additional records came from the Gray Herbarium (gh) and the
New
herbarium of the England Botanical Society (nebc), includ-
M.
by 1879-1880 and K. Wie-
ing collections Hattie Merrifield
in
gand, collecting 1911, and from the herbarium of the Univer-
in
of Massachusetts (mass).
sity
Supplementing herbarium specimens were pub-
several
the
A
lished sources, including Jackson's (1909) Catalogue of the
and addendum
Flowering Plants Ferns Worcester County, an
of
to this flora (Jackson 1927), Tucker's (1894) Frees of Worcester,
328 Rhodora
\Vo\. 104
Stone's (1899) Flora of Lake Quinsigcuno/ui and of Potter
lists
Woodward The
and (1935) and Potter (1940). published
et al.
sources and herbarium reccMxls do not represent a snapshot one
(^f
some
historical time, but rather record species present at point in
1800s
the late or early 19()0s.
Records of the current Intensive work inven-
flora. field to
from 1994-1996, and
tory the current flora ran less intensive
work made
continued 2001. hundred
into several separate visits
T
to over 70 sites during this period. These sites included the range
of natural and disturbed habitats found the City. Records were
in
kept of native and introduced species, and herbarium speci-
all
70%
mens
of approximately of the extant flora were deposited at
MASS.
Data
analysis. analyzing species by used
In loss habitat,
I
habitat descriptions reported in three published floras covering
my
own
the study area, used published information rather than
T
assessments to prevent possible bias. used data from more than
I
one flora to allow for the variation in habitat designations in the
The
different publications. were Gleason and Cronquist
floras
Magee
and Ahles and Seymour
(1991), (1999), (1982). created
I
names
a spreadsheet data hie including of native species
that
all
have been reported in Worcester and habitat descriptions supplied
in each of the three references, then established several habitat
I
categories (Table and identihcd terms found
1), a series of" in the
each For example, bog was
floras that fitted category. habitat
designated by a single term: ''bog.'' Rock outcrop habitat was
designated by
the terms: ''crevice,'' ''ledge,'' ''outcrop/'
''cliff,'^
The
and '"rocks." categories were chosen to represent a variety
of habitats that could be distinguished usini: terms in the floras.
S(Mne categories overlap, and some species were present more
in
A
than one category. computerized search permitted
the
listing
of species each category each For
in habitat in literature source.
few was examine
a habitat categories then necessary to the
it
and
species list delete species clearly inappropriate to that cate-
gory. For example, one search term for aquatic habitat was
"stream." However, term triggered inclusion of species such
this
spicebush Blume], which was
as [L'uulcni
heiizol/i (L.) listed in
one flora as occurring ''along streams."
To
determine habitats associated with particularly high losses.
1
—
2002 Berlin Losses of Native Plant Species 329
examined
Table Habitat categories in this study, along with the habitat
1.
were
terms in floras that used to assign species to these categories.
Terms
Habitat Cateizory Habitat
Aquatic Brooks, floating, lakes, pond, pool, rivers,
springs, streams, submersed, water (excluding
such combinations as ''along rivers")
Bogs Bog
Burned
areas Burn,
fire
Calcareous Alkaline basic calcareous, circumneu-
terrestrial soil, soil,
tral soil, limy soil, neutral, sweet soil (exclud-
ing aquatic species)
Conilerous Cedar, conifer, pine, Thuja
Disturbed sites Buildings, compacted soil, cultivated, disturb,
dooryards, dun^ps, dwellings, garden, gravel
henyards, lawn, pavement,
paths, railroad,
pits,
weed
roadside, sidewalks, stone walls, waste,
Dry herbaceous Dry dry gravelly dry meadow, dry
field, field,
open dry sandy
place, fields
meadow,
Grasslands Field, grass, pasture, prairies
Herbaceous Field, grass, marsh, meadow, openings, pasture,
prairies
Rich
terrestrial Fertile, rich
Rock
outcrc^ps crevice, ledge, cuilcrop, rock
Clift",
Sandy Sand
substrate
swamp
Shrub Shrub
sw^anips
Abandoned
Successional field, old field, serai, successional
Swamp
Swamps
Vciietaled wetlands Bog, marsh, miry, mucky, mud, peat, poorly
swamp,
drained sedge mats,
sites, w^et
Low
Wet meadow, meadows,
herbaceous marsh, moist peaty
swampy
meadow, meadow, wet
springy
field,
wet grassland, wet meadow, wet sunny
field,
Woods wood
Forest,
number was
the of species a particular habitat category
lost in
compared
to the overall rate of species loss using exact prol')a-
based on binomial For example, of 797
a distribution.
bilities
my
native species documented by either herbarium specimens or
sight records, 147 (18.4%) have disappeared. Gleason and Cron-
quist (1991) report 9 of the 797 native species as being associated
Of
with rock outcrops. these, two have disappeared Worcester.
in
Randomly sampling from which 18.4%
nine species a universe in
of species have been one can use the binomial distribution
lost,
to calculate the probability that 1,2, or 9 of
0, 3, 4, 5, 6, 7, 8,
By summing
have been
the nine species will lost. the last eight
Rhodora
330
[Vol. 104
one
of these individual probabilities, finds that the probability of
two more randomly
losing or of nine seleeted speeies 0.52.
is
Losses were considered
in a partieular habitat significantly dif-
from
ferent the overall rate of loss the likelihood of such a loss
if
occurring by chance was less than 0.05. Because 0.52 exceeds
conclude Worcester's rock outcrop species have not
0.05, that
I
been prone
particularly to local extinction.
A
was
similar approach used analyze species disappearances
to
by plant family. Here the grouping was by plant family and the
question asked was: ''Given the overall of species which
rate loss,
showed
families significantly different extinction rates than the
flora as a whole?''
All species and family designations were based on Gleason and
The
Cronquist (1991). rates of loss reported in this paper are
documented
based on species by an herbarium si^ecimcn (the vast
my
by
majority) or sight record (collectively referred to as doc-
umented species). also performed a second set of analyses that
I
documented
included species plus those reported in the literature
(total species). report the results of significance tests involving
I
this group of species, but not the data themselves, which paral-
documented
leled the results for species.
Comparisons of species losses in Worcester to state-wide pat-
made
were from Massa-
terns of rarity using published data the
chusetts Natural Heritage Program (Sorrie and Somers 1999). The
Massachusetts
species at greatest risk are referred to herein as
state-listed species, comprising species that are designated by the
state as endangered, threatened, or of special concern. Species
referred to herein as watch species are those species given
list
informal designation by the Natural Heritage Program. These
this
species are not formally listed, but flagged for monitoring. For
each of these two groups and watch calculated
(state-listed
list),
I
many among
the hkelihood of obtaining as listed species the ex-
tirpated Worcester species sampling randomly from the native
if
species originally present the City using exact binomial prob-
in
abihties.
Changes two
the extent of several habitats the past cen-
in in
were gauged by examining Geological
turies States Sur-
Ui^iited
vey topographic maps drawn and
1935, 1951, 1971, 1982,
in
map
along with a hand-drawn of the City from 1830. Only three
habitats could be distinguished from the maps: forest, wetland,
mm
and water. placed a grid of 5 squares on a transparency
T
—
2002] Bertin Losses of Native Pkint Species 331
number
over each map, and recorded the of grid points falling
in
number
each of the three habitats, alone with the of grid
total
The number
squares within City boundaries. of grid squares
total
was at least 3300 for each map. The proportion of grid squares
was
falling within each of the three habitats taken as the propor-
tion of that habitat in the City at that time.
RESULTS
The analyses presented herein are based on of 820 native
a total
Of
species. these, 797 were documented species and the remain-
ing 23 species were recorded only in published literature and were
my
not observed by me. Most species on which analyses are
based and ffow-
are listed in Bertin (2000), are not repeated here,
examination of Worcester Natural History Society (wnhs)
ever,
specimens the Ecotarium and a few others yielded several doz-
at
Of
and Appendix. 820
en additions changes, the the
listed in total
Of
species, 170 (20. 79^) are no longer found in Worcester. the
797 documented species, 147 (18.4%) no longer occur.
The most
extinction rates for habitat categories did not deviate
from However,
significantly the overall extinction rate (Table
2).
showed
four habitats significantly greater than average extinction
one Species from bogs were
rates in at least analysis. losses sig-
nificantly higher than average for both total losses and docu-
mented losses no matter which flora was used for habitat classi-
Documented from
species losses calcareous
fication. terrestrial
habitats were significantly greater than average for two sources
and for aquatic habitats and coniferous forest for one source each.
Three showed were
habitats species losses that significantly less
one herbaceous
than overall losses for source: disturbed
sites,
and swamps.
vegetation,
taxonomic had documented
In the analysis, six families local
extinction rates significantly higher than for the overall flora:
Menyanthaceae, Ophioglossaceae, Lentibulariaceae, Orchidaceae,
Caryophyllaceae, and Lamiaceae (Table All but the last family
3).
show when undocu-
also significantly elevated species losses
mented
records are included.
The from Worcester
species lost reflect at least partly the pat-
terns of species decline in the entire state. This illustrated by
is
the fact that the proportions of state-listed and watch species
list
among much
those extirpated from Worcester are greater than the
332 Rhodora
[Vol. 104
Documented Sam-
Tabic proportion of species hy habitat category.
2. lost
presumed numbers
ple sizes in parentheses represent the original species in
each habitat. Significant departures from the overall extinction rale are de-
documented
noted as follows; significantly greater, species; significantly
'''
t
+
#
greater, total species; significantly less, docuiiiented species; significantly
species.
less, total
&
Gleason
&
Magee Seymour
Habitat Category Cronquist Ahles
Aquatic 0.28 0.22 (77)t 0.25
(79)^'=t
(6())t
Bogs
0.35 0.33 0,39
(66)-t (5l)^^^t
(72)^^^t
Burned 00
areas 0.25 1.00
(4) 1. (1) (1)
Calcareous 0.25 0.86 0.40 (15)-
terrestrial (20)
(7)='=t
Coniferous 0.50 (8)-t 0.23 (31) 1.00 (1)
Disturbed sites 0.16 (83) 0.11 (215)#+ 0.13 (68)
Dry herbaceous 0.31 (16) 0.14 (43) 0.11 (35)
Dry open woods
0.09 0.29
(11) (21) 0. II (27)
Grasslands 0.18 (139) 0.15 (305) 0.20 (157)
Herbaceous 0.16 (171) 0.15 (337)#+ 0.19 (167)
Rich terrestrial 0.24 (50) 0.19 (104) 0.15 (97)
Rock
outcrops 0.22 0.21 (14) 0.20 (20)
(9)
Sandy
substrate 0.19 (80) 0.25 (71) 0.17 (52)
swamps - -
Shrub
0.09
(0) (23) (0)
-
Successioual 0.05 0.15
(20) (13) (0)
Swamps
0.20 (108) 0.13 (I35)# 0.16 (144)
Vegetated wetlands 0.19 (275) 0.17 (285) 0.16 (268)
Wet
herbaceotis 0. (47) 0.17 60) 0. 12 (17)
(1
1 1
Woods
0.18 (390) 0.17 (491) 0.16 (313)
among
proportion of the listed species the extant flora (Table
4).
\%
For example, state-listed species comprise less than of the
Worcester make up 9.5%
extant native flora, but of the extirpated
Worcester watch comprise
native Similarly, species
flora. list
1.2% of the extant flora, but 12.2% of the extirpated flora. In
among
each case, the proportion of listed species the extirpated
among
flora significantly grcciter than the group of native
is all
<
known
species to liave existed in W(M"cester (P 0.001, exact
binomial
probability).
The extent of forested, wetland and aquatic habitats changed
1830—1982
Worcester during the period (Table Forest hab-
in
5).
was low in the 1800s and early 1900s, increased during the
itat
middle and decreased again the 1900s. Wetland
19()()s, in late
decreased from 800s
habitat sul^stanlially the to the 190()s.
1
Aquatic habitats increased from the 1800s into the early and mid
1900s and then decreased the past 50 years.
in
—
Berlin Losses of Native Plant Species 333
2002]
Table 3. Proporlit)ns of species lost in families having lost more than a
third of original species. Faniilies with two or fewer species are excluded.
Numbers
species per family are given parentheses. denotes signihcant
ol' in '-•'
fiom
departures extinction rales in overall flora.
Documented
Total
Family Species Loss Species
I^oss
Menyanthaceac
1.00 (2)^-^ 1.00 (2)^^^
Ophioglossaccae 0.83 0.83
(6)=== (6)=^^
Ulmaceae
0.67 0.67
(3) (3)
Fumariaceae
0.67 0.67
(3) (3)
Lentibulariaceae 0.67 (6)^^ 0.60 (5)="^
Haloragaceae 0.60 0.30
(5) (4)
Orchidaccae 0.57 (21)- 0.53 (19)==^
Caryophyllaccae 0.56 0.56
(9)^^^ {9y-'
Lamiaceae 0.40 0.40
(15) (15)^-=
Onagraceae 0.40 0.40
(10) (10)
Sparganiaceac 0.40 0.25
(5) (4)
Polamogctonaccae
0.36 0.25
(14) (12)
DISCUSSION
18%
The
Worcester approximately
overall species loss
in is if
one considers only species that have been documented with her-
2\%
barium specimens and one additionally considers species
if
listed for the City only in published records. Several sources of
error are likely to influence these numbers. Despite the consid-
my
amount
erable of time that spent in the field, records are
I
certainly incomplete, and populations of a few species listed here
as extirpated probably remain in the City. Studies from other
examples were
areas are replete with of species reappearing that
once thought be (Dicksc^n 2000; Kent
to locally extinct et al.
An
1975). opposing source of error the incompleteness of the
is
earlier records. Most of the 64 previously unrecorded native spe-
cies probably were present but overlooked earlier work, thtuigh
in
a few could be recent colonizations. Subtracting 64 species from
the number of total known species (820) and documented species
numbers and
(797), leaves the actual of historical records (756
from which
733, respectively) the losses are derived. Tn percent-
22.5% and
age terms, the losses then represent of species
total
20.0% of documented The presence of any undiscovered
species.
species with historical records would lower these numbers, but
few
they are probably accurate within a percentage points.
334 Rhodora
[Vol. 104
among
Table Species loss and persistence slate-listed and watch
4. list
species. species represented by specimens; Cypripediui}} calccolus rep-
''' y is
resent by two varieties, recognized as species in Sorrie and Somcrs (1999),
H — E = T =
one endangered, one on the watch historical, endangered,
list;
=
SC
threatened; special concern. All species are native.
Watch
Species Species
State-listed List
EXTANT
T
laevii^ata (Muh].) Poir; Asclepias tuhcrosci L.
''^'Arahis
&
T
Muhh;
Gray)
''^Elvnuts villosifs ''Biclens cliscoidea (Torr. A.
Britton
n
W. Necs
Potdfuoi^elon vaseyi Rt)b- cdpillcnis (L.)
-i: J. ''^''Eragrostis
E
bins; Isotria vcrticiHatci (Willd.) Raf.
Juglans cincrca
L.
"^''Polygdla vcrticilUila L.
'^'Ribes cimericcniuni Mill.
'''Sporobolus crypiciiuh'iis (Torr.) A.
Gray
= =
Extant species 3/650 Extant watch species 8/650
state-listed
list
-
O.S^A of and documented 1.29f of and documented spe-
total total
species cies
EXTIRPATED
fungosa (Aiton)
''^'Acllumia Biclcfis heckii Torr.
T
Greene;
T
''^'Arerhusci hulhosa L.; '^'Botrychiion lanccolatun} (S. G.
Gmel.)
Angstr.
A
T
purpurascens
Asclep'uts L.; '''Boti'xchiufn DHitricar'uicloliuin
Braun
H
Custillcjci cDcc'nieci (L.) Spreng.: ''''Boirychiu/n oncidcfise (Gilbert)
House
'''Cypripediui}} calccolus L.; Et '-''Ccirdd/nifie rhoiiiboidea (Pers.)
Alph. de Candollc
'^'Eriophorum gracile W. D. Carex diandra Schrank
J
T
Koch;
Galium E Carex Dewey
barecdc haydenii
L.;
T
"^''Ilabcnaria ftava (L.) R. Br.; ''•''Chenoj^odiu/n gigcnitospcnuuni Ael-
len
E
Isoctes hu-uslris L.; '''Cypripcdiuni calccolus L.t
E
Juncu.s ^'Dryoptcris goldiaua (Hooker) A.
Jiliforniis L.;
Gray
Ma
SC
'^dJatris scariosa (L.) Willd.; "^'Goitiauopsis criuiia (Fi'oel.)
'-"'Lygodium paluialuin (Bernh.) '''d^abenaria lu)okeri Torr.
SC
Sw.;
-|: Myriopliylluni aUeniiJtoru}}}\ '•'Habenaria viridis (L.) R. Br
T
Alph. dc Candollc;
E
"^Myriophyllufi^ verticiUatuni E.; '•djipifms pereunis L.
'''Ojdiioglossum vulgatuni (Blake) Malaxis unijblia Michx.
T
Farw.;
'Panax SC Michx
quincjucfolius L.; '''Polygonuui tenue