Slender Bush-clover (Lespedeza virginica) in Ontario - Ontario Recovery Strategy Series
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Photo: Allen Woodliffe
Slender Bush-clover
(Lespedeza virginica) in Ontario
Ontario Recovery
Strategy Series
Recovery strategy prepared under the Endangered Species Act, 2007
2013
Ministry of Natural Resources
About the Ontario Recovery Strategy Series
This series presents the collection of recovery strategies that are prepared or adopted
as advice to the Province of Ontario on the recommended approach to recover
species at risk. The Province ensures the preparation of recovery strategies to meet
its commitments to recover species at risk under the Endangered Species Act
(ESA) and the Accord for the Protection of Species at Risk in Canada.
What is recovery? What’s next?
Recovery of species at risk is the process by which the Nine months after the completion of a recovery strategy
decline of an endangered, threatened, or extirpated a government response statement will be published
species is arrested or reversed, and threats are which summarizes the actions that the Government of
removed or reduced to improve the likelihood of a Ontario intends to take in response to the strategy.
species’ persistence in the wild. The implementation of recovery strategies depends on
the continued cooperation and actions of government
agencies, individuals, communities, land users, and
What is a recovery strategy? conservationists.
Under the ESA a recovery strategy provides the best
available scientific knowledge on what is required to
For more information
achieve recovery of a species. A recovery strategy
outlines the habitat needs and the threats to the To learn more about species at risk recovery in Ontario,
survival and recovery of the species. It also makes please visit the Ministry of Natural Resources Species at
recommendations on the objectives for protection and Risk webpage at: www.ontario.ca/speciesatrisk
recovery, the approaches to achieve those objectives,
and the area that should be considered in the
development of a habitat regulation. Sections 11 to 15
of the ESA outline the required content and timelines
for developing recovery strategies published in this
series.
Recovery strategies are required to be prepared for
endangered and threatened species within one or two
years respectively of the species being added to the
Species at Risk in Ontario list. There is a transition period
of five years (until June 30, 2013) to develop recovery
strategies for those species listed as endangered or
threatened in the schedules of the ESA. Recovery
strategies are required to be prepared for extirpated
species only if reintroduction is considered feasible.
Recovery Strategy for the Slender Bush-clover in Ontario
RECOMMENDED CITATION
Jones, J. 2013. Recovery Strategy for the Slender Bush-clover (Lespedeza virginica) in
Ontario. Ontario Recovery Strategy Series. Prepared for the Ontario Ministry of Natural
Resources, Peterborough, Ontario. vi + 26 pp.
Cover illustration: Slender Bush-clover at Ojibway Prairie by Karen Cedar.
This photo may not be reproduced separately from this recovery strategy without
permission of the photographer.
© Queen’s Printer for Ontario, 2013
ISBN 978-4606-3063-1(PDF)
Content (excluding the cover illustration) may be used without permission, with
appropriate credit to the source.
Cette publication hautement spécialisée Recovery strategies prepared under the
Endangered Species Act, 2007, n’est disponible qu’en Anglais en vertu du Règlement
411/97 qui en exempte l’application de la Loi sur les services en français. Pour obtenir
de l’aide en français, veuillez communiquer avec Pamela Wesley au ministère des
Richesses naturelles au 705-755-5217.
iRecovery Strategy for the Slender Bush-clover in Ontario
AUTHORS
Judith Jones, Winter Spider Eco-Consulting, Sheguiandah, Ontario
ACKNOWLEDGMENTS
The Committee on the Status of Endangered Wildlife in Canada is thanked for providing
information from the 6-month interim 2012 status report. Thanks to Sam Brinker and
Mike Oldham for providing additional information on habitat; to P. Allen Woodliffe for the
photo in Figure 1 and for information from past field work; to Paul Pratt for providing
data from the Ojibway Nature Centre; and to Karen Cedar of the Ojibway Nature Centre
for providing the cover photo.
iiRecovery Strategy for the Slender Bush-clover in Ontario
DECLARATION
The recovery strategy for the Slender Bush-clover was developed in accordance with
the requirements of the Endangered Species Act, 2007 (ESA). This recovery strategy
has been prepared as advice to the Government of Ontario, other responsible
jurisdictions and the many different constituencies that may be involved in recovering
the species.
The recovery strategy does not necessarily represent the views of all of the individuals
who provided advice or contributed to its preparation, or the official positions of the
organizations with which the individuals are associated.
The goals, objectives and recovery approaches identified in the strategy are based on
the best available knowledge and are subject to revision as new information becomes
available. Implementation of this strategy is subject to appropriations, priorities and
budgetary constraints of the participating jurisdictions and organizations.
Success in the recovery of this species depends on the commitment and cooperation of
many different constituencies that will be involved in implementing the directions set out
in this strategy.
RESPONSIBLE JURISDICTIONS
Ontario Ministry of Natural Resources
Environment Canada – Canadian Wildlife Service, Ontario
iiiRecovery Strategy for the Slender Bush-clover in Ontario
EXECUTIVE SUMMARY
Slender Bush-clover (Lespedeza virginica) is listed as endangered under Ontario’s
Endangered Species Act, 2007 and on Schedule 1 of the federal Species at Risk Act. It
is a perennial herb in the Pea Family with pink flowers and many narrow leaves
crowded on upright stems. The seeds can remain viable for decades and can pass
unharmed through the gut of an animal.
In Canada, Slender Bush-clover is present only in Ojibway Park and possibly at
Tallgrass Heritage Park and Black Oak Heritage Park, all part of the Ojibway Prairie
Complex in the City of Windsor, Ontario. Collectively, these three sites comprise a
single population. The species has not been seen at Tallgrass Park since 1997 or at
Black Oak Park since 1993. It is unknown whether the seed bank is still viable at these
locations. Plants growing above ground were seen at Ojibway Park in 2011.
In Ontario, Slender Bush-clover is extremely limited by a lack of suitable habitat. In this
province, the species is restricted to dry-mesic tallgrass prairie relicts with patches of
exposed sandy soil. It requires full sun and open ground and does not tolerate dense
shade or competition from surrounding vegetation. Some type of disturbance is needed
to create open soil. Historically, this was probably fire or periodic drought. Existing
habitat is highly fragmented into small patches that are isolated from one another by
distances of hundreds of metres or more. Disturbance factors are also needed to
disrupt the seed coat to improve germination.
Slender Bush-clover may be limited by some aspects of its reproductive biology. First,
the relatively short growing season in Ontario might cause lower seed productivity than
is found in populations in the southern part of the species' range. Second, factors
responsible for breaking seed dormancy (such as fire, abrasion by sand, ingestion by
herbivores) might be lacking at extant sites. Finally, the small, isolated Canadian
population of Slender Bush-clover is at risk of being destroyed by a single stochastic
event, such as a flood or wind storm.
The most serious threat to Slender Bush-clover is alteration of the natural disturbance
regime (e.g., suppression of natural wildfire), which allows natural succession to
proceed, resulting in habitat degradation or loss. Invasive species are another threat in
need of urgent attention. All-terrain vehicle and dirt bike use are no longer threats.
The recovery goal is to maintain the abundance and distribution of growing plants of
Slender Bush-clover at Ojibway Park at current or greater levels by reducing threats,
and if the species is extant in the seed bank at the other two subpopulations, to
increase the number of growing plants present there to pre-1995 levels. The protection
and recovery objectives are to:
1. maintain or improve habitat suitability at the three existing sites;
2. reduce presence of invasive species at the three existing sites;
3. fill knowledge gaps; and
4. increase population size and extent if deemed feasible.
ivRecovery Strategy for the Slender Bush-clover in Ontario
It is recommended that a habitat regulation cover all three Windsor sites and that at
Ojibway Park the entire opening where the species occurs plus a protective zone of 50
m around the outside of the opening be prescribed. A definition of "opening" is given in
the body of the text. At Tallgrass and Black Oak Heritage Parks it is recommended that
a 50 m zone around the former area of live plants be prescribed as habitat to protect the
seed bank and allow disturbance to occur even though live plants have not been seen
in recent years. It is recommended that the Tallgrass and Black Oak sites be
prescribed for 50 years unless live, growing plants of Slender Bush-clover re-emerge in
which case habitat would remain prescribed beyond this time. It is recommended that
restoration populations be regulated if they are planted within the three parks where the
species is endangered and in natural vegetation but not in garden beds.
vRecovery Strategy for the Slender Bush-clover in Ontario
TABLE OF CONTENTS
RECOMMENDED CITATION ........................................................................................... i
AUTHORS ....................................................................................................................... ii
ACKNOWLEDGMENTS .................................................................................................. ii
DECLARATION ............................................................................................................... iii
RESPONSIBLE JURISDICTIONS .................................................................................. iii
EXECUTIVE SUMMARY.................................................................................................iv
1.0 BACKGROUND INFORMATION .......................................................................... 1
1.1 Species Assessment and Classification ............................................................ 1
1.2 Species Description and Biology....................................................................... 1
1.3 Distribution, Abundance and Population Trends ............................................... 4
1.4 Habitat Needs ................................................................................................... 7
1.5 Limiting Factors ................................................................................................. 8
1.6 Threats to Survival and Recovery ..................................................................... 9
1.7 Knowledge Gaps............................................................................................. 10
1.8 Recovery Actions Completed or Underway..................................................... 11
2.0 RECOVERY ....................................................................................................... 13
2.1 Recovery Goal ................................................................................................ 13
2.2 Protection and Recovery Objectives ............................................................... 13
2.3 Approaches to Recovery ................................................................................. 14
2.4 Area for Consideration in Developing a Habitat Regulation ............................ 17
GLOSSARY .................................................................................................................. 21
REFERENCES .............................................................................................................. 23
LIST OF FIGURES
Figure 1. Flowering clusters of Slender Bush-clover ...................................................... 2
Figure 2. Historical and current distribution of Slender Bush-clover in Ontario. ............. 5
LIST OF TABLES
Table 1. Conservation ranking for Slender Bush-clover. ................................................ 5
Table 2. Abundance of Slender Bush-clover at the Ojibway Park site............................ 6
Table 3. Protection and recovery objectives................................................................. 13
Table 4. Approaches to recovery of the Slender Bush-clover in Ontario. ..................... 14
viRecovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
1.0 BACKGR
ROUND IN
NFORMAT
TION
1.1 Species
S Assessme
A ent and Classifica
C ation
COMMO
ON NAME: Slender Bush-clover
B r
SCIENT
TIFIC NAME
E: Lespede
eza virginica
SARO List
L Classificcation: End
dangered (wwithin Tallgrrass Prairie
e Heritage P
Park, Ojibw
way
Park and
d Black Oak Heritage Park in the
e City of Winndsor)
SARO List
L History: Endangere
ed (2008), Endangere
ed – Regula
ated (2004)
COSEW
WIC Assessment History: Endang
gered (2000
0, 1986)
SARA Schedule
S 1: Endangere
ed
CONSERVATION STATUS RANKINGS:
R :
GRANNK: G5 NRANK: N
N1 SRANK: S1
The glosssary provid
des definitio
ons for the abbreviatio
ons above a
and for othe
er technical
terms in this recove
ery strategy
y.
1.2 Species
S Descriptio
D on and Biiology
Species Description
Slender Bush-clove er (Lespede
eza virginicca (L.) Britto
on) is a pere ennial herb
b in the Legume
or Pea Family
F (Fabbaceae). The upright hairy
h stemss, 30 to 100 0 cm tall, arrise from a
woody rhizome and d sometimees branch near
n the top p. Numerou us narrow, tthree-parte ed
leaves thhat are stroongly ascennding (pointting up) gro ow from the e main stem m on short (1
cm) stalks, giving th he stem a crowded,
c sppike-like proofile. In latte summer, small, purp ple
to pink pea-like
p flow
wers, 4 to 7 mm acros ss, are prodduced in sho ort clusters in the axilss of
the leaves (Figure 1). Two typ pes of floweers are prod duced: thosse that ope en and have e
showy petals,
p and those that are
a smallerr, remain clo osed, and a are self-ferttile. Follow
wing
pollinatio
on, a flat, oval-shaped
o d pod 4-7 mm
m in diame eter contain ning one se eed is produ uced
from botth types of flowers
f (Cle
ewell 1966, Gleason a and Cronqu uist 1991).
Slender Bush-clove er may be distinguishe
d ed from oth er species of Bush-clo over that ha
ave
upright stems
s and purple-colooured petalss by the folllowing charracteristics::
narrow, strap-shaped le eaves (not oval shape ed);
le eaves some ewhat hairyy (but not de
ensely velvvety);
numerous, non-opening
n g flowers present (mo ore than justt a few pressent), and
flowers with open corolllas on shorrt stalks or sitting direcctly on the sstem (not oon
sttalks nearly
y the length
h of leaves).
1Recovery Strategy for the Slender Bush-clover in Ontario
Figure 1. Flowering clusters of Slender Bush-clover showing both the showy and the
non-opening flowers. (Photo: P.A. Woodliffe. This photo may not be reproduced
separately from this document without permission of the photographer.)
Species Biology
Slender Bush-clover is a perennial that comes up each year from underground woody
rhizomes. Clewell (1964) counted the annual growth rings on rhizomes of Hairy Bush-
clover (L. hirta) and Wand-like Bush-clover (L. intermedia) in southern Indiana and
found plants lived up to 13 to 17 years, which may give an indication of the potential life
span of the growing plants of Slender Bush-clover as well. Like other plants in the
Legume family, Slender Bush-clover has nitrogen-fixing bacteria in nodules on the
rhizome (Yao et al. 2002). This symbiotic association enables Slender Bush-clover to
grow in nitrogen-poor soils.
In Ontario, Slender Bush-clover flowers in August and September and produces both
open (chastogamous) flowers and closed (cleistogamous) flowers that self-pollinate.
Both kinds of flowers produce viable seed. The ratio of the different flower types
produced may change in response to different environmental conditions or stresses
(Clewell 1964, Schutzenhofer 2007). More closed flowers are produced when plants
are stressed. These flowers have smaller petals and no nectar and require less energy
to produce. Thus, they may be a smaller energy investment that guarantees
reproduction when conditions are less than optimal.
The open flowers of Slender Bush-clover are likely pollinated by a variety of insect
2Recovery Strategy for the Slender Bush-clover in Ontario
species, with bees, butterflies, and moths probably being the main pollinators (Pratt
1986). Clewell (1966) observed honeybees and several types of bumblebees on bush-
clovers in Indiana. Simpson (1999) removed competing species in plots to see if
Slender Bush-clover was limited by pollination. In the first year, she found an increase
in insect visits but no increase in seed-set and concluded that pollination was already
above a threshold level for seed set. In the second year, she found a stronger
correlation between insect visits and amount of seed set because overall visitation was
low. This suggests that Slender Bush-clover can be limited by pollination depending on
conditions for pollinators in any given year.
Both the showy and non-opening flowers of Slender Bush-clover produce viable seeds.
However, seeds of non-opening flowers have slightly lower viability (Schutzenhofer
2007). Schutzenhofer (2007) examined the effects of herbivory on the production of
both types of flowers and found that herbivory resulted in an increase in the ratio of non-
opening flowers over showy flowers. Since seeds of non-opening flowers have lower
viability, this change in ratio may have consequences for overall reproductive success.
No significant difference was found in germination rates between seeds produced from
showy flowers and those of non-opening flowers, but rates for both types of seeds were
low. No analysis has been done that would take into consideration any benefit provided
if herbivory results in increased seed dispersal distances or improved seed germination
rates. It can be speculated that the amount of herbivory within a patch, as well as the
parts of the plant eaten, may make a difference.
The seeds of Slender Bush-clover have a hard, impervious seed coat that permits them
to pass unharmed through animal digestive systems and to remain viable in the soil for
long periods of time. The seed coat must be scarified or disrupted in some way before
germination can occur. Passage through an animal gut may improve germination for
seeds of Slender Bush-clover. Blocksome (2006) found improved germination rates for
seeds of Chinese Bush-clover (L. juncea var. sericea) after passage through the gut of
quail. Clewell (1966) reported a 100% germination rate for seeds of Slender Bush-
clover manually scarified with a scalpel versus 0% for seed that was not scarified. As
well, Clewell (1966) successfully germinated seeds taken from a 54-year-old herbarium
specimen, showing that under some conditions seeds may remain viable for many
decades. The actual time that Slender Bush-clover seeds can remain viable outdoors in
soil is unknown. If seeds do not pass through an animal gut, some other natural
process may be needed to disrupt the seed coat. It can be speculated that fire or
possibly abrasion by sand may provide this function.
At the Ontario location for Slender Bush-clover, in the Ojibway Prairie Complex in the
City of Windsor, a number of animals and birds are present that may eat the seeds of
Slender Bush-clover, including White-tailed Deer (Odocoileus virginianus), Northern
Bobwhite (Colinus virginianus), Wild Turkey (Meleagris gallopavo) and Mourning Dove
(Zenaida macroura), as well as many small mammals such as mice and rats (Pratt
1986, Blocksome 2006, Ojibway Nature Centre 2012). The seed of Slender Bush-
clover may be dispersed by animals if eaten and expelled in feces at another location.
It is not known whether animals are the main dispersal vector of Slender Bush-clover,
3Recovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
but some other spe ecies of bus
sh-clovers are
a dispersed primarilyy by animals (Blockso ome
2006). The
T likeliho ood of the seed
s of Slen
nder Bush-cclover passsing through h the gut ra
ather
than being broken down durin ng digestionn is not knowwn, but it iss possible that an animmal
may be both a seed d predator and an occ casional disspersal vecttor. There may be a
trade-offf between having
h a se
eed that is an
a attractivee food sourrce to anima al vectors a
and
losing so
ome seed tot animal diigestion. If not eaten, the fruits oof Slender B Bush-cloverr
stay on the plant th
hrough the fall
f and win nter, eventu
ually falling and openin ng to releasse
the seedd (Clewell 1966).
1
Several ecological processes must occur for successsful germination. The ese include e
suitable disturbanc ce to exposee mineral soils (ground d fires, scra
aping, etc.) and action ns
that scarify or disru
upt the seedd coat (fire, passage th hrough an a animal gut, being rubb bed
by sand, etc.) as well
w as suitable moisturre condition ns. In contrrolled garde en trials in
Indiana, Clewell (19 966) found plants of Hairy
H and WWand-like Bush-clover were able tto
reach maturity
m and bear seed in the first year after g germination n, but foundd seedlings in
natural populations
p s either didn
n't flower in the first ye
ear or floweered but pro oduced few
seeds. It is unknow wn whetherr flowering in i the first yyear is posssible for Sle
ender Bush h-
n Ontario. The
clover in T species s also is abble to sprea ad from sho ort, undergro ound stolon ns or
from fraggments of the
t woody rhizome
r (Clewell 1964 4). The pre esence of underground d
woody rhizomes, a hard seed coat, and the t ability to o spread froom fragments are
adaptations that alllow Slender Bush-clov ver to survivve the fire oor other dissturbance th hat is
requiredd to create and
a maintain suitable habitat.
Slender Bush-clove er appears to be a pooor competito or and growws best when not crow wded
by otherr vegetation
n. In a stud
dy of severaal species oof bush-clovver growing g on both
eroded and
a non-ero oded soils, Slender Buush-clover g grew taller and had increased yie eld
(dried biiomass), inc
creased winnter surviva
al and grea ter survivall of seedling
gs in plots tthat
were we eeded to redduce comp petition rega
ardless of ssoil type (Ha
arris and Drrew 1943).
1.3 Distributio
D on, Abun
ndance an
nd Popula
ation Tre
ends
In Canada, Slender Bush-clov ver has beeen documen nted only in
n southwesttern Ontario o
(Figure 2).
2 In the United
U State
es, Slenderr Bush-clovver is found in 26 state es, and in
northernn Mexico it is
i present in the state of Nuevo L Leon. Table e 1 shows tthe state orr
provinciaal conservaation rankin
ngs (S ranks s) for Slend
der Bush-clover (NaturreServe 20 012).
The spe ecies is not consideredd rare within
n the core oof its Midwe
estern range but is ran nked
rare in northern
n are
eas. In adddition, Slend
der Bush-cllover is legaally listed a
as threateneed in
New Hampshire an nd Wisconsin. Globally, the speccies is considered secu ure and ran
nked
G5 (NatureServe 2012).
2
4Recovery Strategy for the Slender Bush-clover in Ontario
Figure 2. Historical and current distribution of Slender Bush-clover in Ontario.
Solid circle: extant population consisting of three subpopulations in the Ojibway Prairie
Complex in the City of Windsor. Open circle: historical record from the Leamington area
not seen since 1892.
Table 1. Conservation ranking for Slender Bush-clover by state or province
(NatureServe 2012).
State or Provincial Conservation Rank States with this rank
Critically imperilled (S1) New Hampshire, Ontario
Imperilled (S2) Wisconsin
Possibly vulnerable (S3?) New York
Apparently secure (S4) Iowa, Virginia, West Virginia
Secure (S5) Delaware, Kentucky, New Jersey, North Carolina
Not ranked (SNR) Alabama, Arkansas, Connecticut, District of Columbia, Florida,
Georgia, Illinois, Indiana, Kansas, Louisiana, Maryland,
Massachusetts, Michigan, Mississippi, Missouri, Ohio,
Oklahoma, Pennsylvania, Rhode Island, South Carolina,
Tennessee, Texas;
Mexico: Nuevo Leon
5Recovery Strategy for the Slender Bush-clover in Ontario
In Ontario, Slender Bush-clover is present only in the Ojibway Prairie Complex in the
City of Windsor. In that area, the species has been documented from three sites,
Tallgrass Heritage Park, Black Oak Heritage Park, and Ojibway Park, all of which
qualify as subpopulations of a single population or occurrence according to the criteria
used by the Natural Heritage Information Centre (NHIC 2012)1. All three sites are in
parks managed by the City of Windsor, Department of Parks and Recreation.
The species was first discovered at Tallgrass Heritage Park in 1977. Plants were
observed there in 1978, 1979, 1982, 1984 and 1997 but were not found in 2000 or 2011
(NHIC 2012). Abundance was not documented except in 1984 when approximately 150
plants were reported. In 2000, the site was reported to be too shaded-in and dense with
understory vegetation (NHIC 2012), and the loss of the Slender Bush-clover plants at
this site has been attributed to natural succession (COSEWIC 2012a).
In 1993, a single Slender Bush-clover plant was observed in Black Oak Heritage Park
along a walking trail. The site was visited in 1997 and 2011 but the species was not
found and may have been destroyed by all-terrain vehicles (ATVs) (COSEWIC 2000,
COSEWIC 2012a).
In 1979, Slender Bush-clover was discovered at Ojibway Park. The plants were not
found in 1984 for the first COSEWIC status report (Pratt 1986) but were observed and
documented in 1986, 1997, 2000 and 2011 (COSEWIC 2000, NHIC 2012). Abundance
of Slender Bush-clover at this site is shown in Table 2.
Table 2. Abundance of Slender Bush-clover at the Ojibway Park site (NHIC 2012)
Date Abundance Observers
1979 ~50 plants P.D. Pratt
1984 0 P.D. Pratt
1986 "a few" M.J. Oldham
1997 160 K. Cedar
2000 >24 D. Jacobs, P.D. Pratt, P.A.
Woodliffe & K. Cedar
2011 165 S.R. Brinker, M.J. Oldham, C.D.
Jones
Due to Slender Bush-clover's long-lived seed viability, it is possible the species may be
extant in the seed bank and could potentially reoccur at any of the three sites in the
Ojibway Prairie Complex even though live plants of Slender Bush-clover have only been
seen in recent years at the Ojibway Park site. Therefore, all three sites must still be
considered extant locations.
Only generalized conclusions can be made about population trends because the
populations have not been consistently observed, but overall there appears to be a
1
All patches that occur within 1 km of each other are considered to belong to the same population or
occurrence. Patches at greater distance may also be included if there is no significant break or change in
the habitat. See NHIC (2012) for a detailed definition of occurrence.
6Recovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
decline in
i populatio
on size in th
he last 25 years.
y The loss of the plants at thhe Tallgrasss
Heritage
e Park site, from 150 plants
p in 1984 to 8 plannts in 1997
7 to 0 in 20111, likely du
ue to
successsion (COSE EWIC 2000)), is certainlly a decline
e. The loss of the plannts at Blackk
Oak Herritage Park, probably from
f ATVs, is another decline. A At the Ojibw
way Park sitte,
the data
a show man ons and an overall slig ht increase
ny fluctuatio e from the pprevious hig gh of
160 in 1997 to 165 in 2011 (NNHIC 2012).. However,, generally, the trend in the last 2 25
years in Ontario ap
ppears to bee one of deecline and ppossibly the
e loss of site
es.
Historica
ally, Slende
er Bush-clov ver was alsso present iin the Leammington area, where it was
collected
d by Macou un in 1892 (NHIC
( 20122). Howeve er, the popu ulation therre has neveer
been rellocated desspite many focused se earches. Th he area is nnow heavilyy urbanized d or
converteed to agricu
ulture (Prattt 1986). In addition, th
here is a hisstorical report of Slend
der
Bush-cloover from th
he Niagara Region ma ade by W. S Scott in 18996; howeve er, the reporrt is
not backked up by a collected specimen
s and
a the reco ord is considered likely an error
(COSEW WIC 2000).
1.4 Habitat
H Ne
eeds
In Canada, Slender Bush-clov ver is restric
cted to dry--mesic tallg
grass prairie
e relicts with
h
patches of exposed d sandy soiil. In 2011, the Ontario o habitat w
was reported d to be sanddy
openings in oak wo oods with Little Blueste em (Schiza achyrium sccoparium), C Crown Vetcch
(Securig
gera varia), Black Oak (Quercus velutina),
v C
Canadian Tiick-Trefoil ((Desmodium m
canaden nse), Feather Three-aw wn (Aristidaa purpurasccens), Densse Blazing Star (Liatriss
spicata), and Spottted Knapwe eed (Centau urea stoebe e) (NHIC 20 012). The Ecological
Land Claassification
n (ELC) veg getation typee (Lee et al. 1998) of tthe current Ontario
location is describe
ed as Dry Black
B Oak Tallgrass
T Saavannah (T TPS1-1) (P.A A. Woodlifffe,
pers. comm. 2012) or possibly y Dry Blackk Oak Tallgrrass Woodland (TPW 1-1) at the
sites wh
here vegetation cover hash increas sed and clo osed in mosst of the ope en area. AAs
the speccies occupiees the open n patches within
w these e vegetationn communitty types, it ccan
be assumed that DryD Tallgrass Prairie (T TPO1-1) wo ould also prrovide suitable habitat..
The speecies requirees full sun and
a open ground
g for e
establishme ent of seedllings and does
not appeear to be abble to grow in dense shade or witthstand eve en moderatte levels of
competittion from suurrounding vegetation (Pratt 1986 6, COSEW WIC 2000). The openin ng at
Ojibwayy Park wherre the speciies currently occurs is approxima ately .33 ha.
The requ uirement foor open soil indicates that some tyype of distu urbance (su uch as fire,
periodic drought orr anthropogenic disturb bance) is neeeded for mmaintenancce of suitable
habitat conditions.
c Without it, the open ground
g wou uld be expected to beccome coverred
with thattch from a build-up
b of leaves and d organic m aterials andd to fill in w
with vegetation
from nattural succes ssion, becooming unsuitable for S Slender Bussh-clover. H Historically,,
bare groound probab bly resulted
d from fire but
b now like ely comes m mainly from m other typees of
disturbance. Pratt (1986) repo orts that at the Tallgra
ass Heritagee Park site,, Slender B Bush-
clover plants were located in ana area where the gro ound was sccraped. He e adds that
1948 airr photos sho ow an open n trail a few
w metres ea ast of where
e the plantss were locatted,
so the trrail may also have previously provided some e disturbance. Howevver, he also o
7Recovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
reports that
t spring fires burned through the area in 1978, 1980 0 and 1983 and occurrred
within 10
00 m of thee population
n in 1976, 1977 and 19984, so it iss possible th
hat fire help
ped
maintainn the opennness of the area during
g the time t hat the habbitat remain
ned suitablee.
The freqquency at which
w disturbance is re equired, or tthe time peeriod over wwhich the
habitat may
m becom me too heav vily vegetateed to be suitable, is un nknown. Acccording to o
Pratt (19
986), the sccrape at Tallgrass Herritage Park probably da ated from a around 1958,
and was s therefore roughly 26 years old in 1986. Be etween 197 75 and 1986 6, Pratt
observed little appaarent chang ge in the sitte, indicatin
ng a very sloow rate of ssuccession,
especiallly in the ce
entre of the scraped arrea, during that nine-yyear period. This was also
a periodd in which fire and humman disturba ance were occurring ssporadicallyy. By 1997,
there waas almost non open min neral soil prresent (COS SEWIC 200 00) and onlly eight Slender
Bush-cloover plants were found d. Thus, it appears the e habitat beecame sign nificantly
degrade ed in the 13 years betw ween 1984 and 1997. It can be sspeculated that fire or
disturbance may be e needed every
e 3 to 13 years, an nd probablyy closer to the more
frequentt end of thaat range since plants had nearly d disappeared d after 13 yyears.
Optimal habitat for Slender Bu ush-clover contains
c a sspecific asssociation off prairie forbs
(Pratt 19 986), but sppecies composition in the habitat has probab bly changed somewha at in
the last 25 years, possibly
p indicating an overall
o degradation. P Pratt (1986)) listed 12
species frequently associated with Slend der Bush-cloover and 12 2 rare speccies (based on
Argus an nd White 19 977, 1982 and
a 1983, and a Argus a and Keddy 1984) that were found d
within 1 m of Slend der Bush-clo
over. Of these, only twwo of the foormer frequuent associa ates
and only y three of th
he former ra
are speciess were pressent in 2011 1 (COSEWIC 2012a).
Still, it is
s possible th
hat some of
o this differe
ence may bbe due to th he reduction n in the num mber
of sites as a well.
COSEW WIC (2012a)) listed 34 plant
p speciees growing within 1 m of Slender Bush-clove er
during fieldwork in Septemberr of 2011. Most
M are prrairie-obliga
ates or speccies of old
fields. One
O of these e, Dense Bllazing Star (Liatris spiicata) is fedderally and provinciallyy
listed as
s Threateneed, and threee are listed
d as rare in Ontario: AArrow Feath her Three-awn
(Aristida
a purpurasccens – S1), Tall Coreopsis (Coreo opsis tripterris—S2), annd Round-
fruited Panic
P Grasss (Dicanthelium sphae erocarpon— —S3) (COSE EWIC 2012 2b, NHIC 20 012).
gan, Slende
In Michig er Bush-cloover is found in 17 cou unties in habitats that iinclude dry
open wo oods (espec cially oak), prairies, sh
hores, fieldss, railroad b
banks and oopen hills
(Voss 19985, Reznic cek et al. 20
011). It is unknown
u w
why the speccies occurss in more
locations
s and in a wider
w range
e of habitatss in Michiga an than in OOntario. Th
hroughout itts
global ra
ange, the species is no ot restricted
d to sandy ssoils, and inn some staates the speecies
is found at latitudes
s more norttherly than Windsor.
1.5 Limiting
L Factors
F
In Ontarrio, Slenderr Bush-clover is extremmely limitedd by a lack o
of suitable habitat. Off the
hundredds of square e kilometres
s of tallgras
ss prairie annd savannaah documen nted in earlly
8Recovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
settleme ent times, only
o about 2100
2 ha or 0.5%
0 rema ains, with the majority llost to
agricultuural use and d residentia
al developmment (Bakow wsky and R Riley 1994).. Today, appart
from thee Ojibway Prairie
P Complex and arreas on Wa alpole Islandd, most rem
mnant patchhes
are sma all (less thann 2 ha) andd isolated. Natural
N eco
ological proocesses, such as the
occurren nce of wildffire, are sev
verely comp promised inn such small patches. Suitable
prairie habitat
h for Slender
S Bussh-clover is highly frag
gmented intto small pattches that a
are
isolated from one another
a by distances
d of
o hundredss of metres or more. T This probabbly
limits the
e ability of Slender
S Bush-clover too expand innto new are eas (COSEW WIC 2000).
Mature fruiting
f plan
nts of Slendder Bush-cloover producce only a fe
ew hundred d seeds, wh hich
may redduce the rep productive capacity
c of the speciess (COSEWWIC 2000). In addition,,
these seeeds require e scarification before they
t can geerminate annd the natural factors
which hiistorically may
m have prrovided this s process (ssuch as fire
e, specific tyypes of animal
vectors, etc.) may now
n be unc common or no longer o occur. Low w reproducttive capacity is
not an in
nherent limitation in the genus sin nce some sspecies of bbush-cloverrs, such as
Silky Bu
ush-clover (Lespedeza a cuneata) are
a invasive e on rangelland (Blockksome 2006 6).
It is posssible that th
he climate of
o Ontario, the
t northerrn part of thhe species rrange, mayy be
a limitatiion to Slendder Bush-cllover. The species flo owers at thee end of the e summer aand
must set seed befo ore the end of the grow
wing season n. This time frame is sshorter in
Ontario than it is in the core of the specie es' range in
n the centraal Midwest, and probab bly
occasion nally resultss in low or lost
l seed se
et in years when there e is early fro
ost or snow
wfall.
Finally, the
t populattion of Slender Bush-c clover in Caanada is very small and isolated a and
thus at risk
r of being g destroyedd by a single stochastic event, su uch as a floood or wind
storm. A severe sttorm wiped out a popu ulation that had been p planted in LLambton Co ounty
as part of
o an experrimental res
storation (R
R. Ludolph, pers. comm m. 2012). A single eve ent
could remove the entire
e popullation, espe
ecially since
e the live pllants curren
ntly occupyy an
area of only
o 9 by 4 m (COSEW WIC 2012a).
1.6 Threats
T to
o Surviva
al and Rec
covery
Observe ed Threats
Altered Disturbance
D e Regime
The mos st serious current
c threat to Slender Bush-clo over is degrradation or loss of hab bitat
from fire
e suppressio on or otherr changes too the naturaal disturban
nce regime. Without
disturbance of som me type, nattural succes ssion takess place and open areas fill in with
vegetation, coverin ng up the oppen ground required fo or germinattion and groowth. Slender
Bush-clo over does not
n compete e well with surroundingg vegetatioon, so the in
ncreased co over
of other plants is a serious detriment thatt can ultimaately lead too a complette decline a and
he population. Degrad
loss of th dation of ha
abitat contin
nues to be an active th hreat despiite
all three locations for
f the spec cies being in protectedd, managed d parks. Th he filling in o
of
vegetation is likely the main faactor responsible for thhe lack of g
growing plants and
possible e Tallgrass Heritage Park populattion (COSE
e loss of the EWIC 2012a a).
9Recovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
c burning is conducted within the Ojibway Prrairie Comp
Periodic plex and all three sitess for
Slender Bush-clove er have bee en burned occasionally
o y in the passt with enouugh intensitty to
remove leaf litter and blacken soil. Howe ever, the fre
equency off burns has been low in
Ojibwayy Park and Tallgrass
T Prairie Herita
age Park (P P.D. Pratt, p
pers. comm m. 2012).
Whetherr due to loww intensity, low frequen ncy or a coombination, it appears that the
burning done was insufficient
i to maintain
n the habitaat at the Talllgrass and Black Oakk
Park site
es. Lack off fire or othe
er disturbannce contributes to hab bitat loss byy allowing a
build-up of leaves and
a organic c materials (dead plan nts and grasss) to coverr patches o of
exposed d soil.
Invasivee Species
Crown Vetch
V (Secu urigera variia), Autumn
n Olive (Ela eagnus um
mbellata) an nd Spotted
Knapwe eed (Centau urea stoebee ssp. micraanthos) are
e present wiithin 1 m off Slender Bush-
clover plants (COS SEWIC 2012 2a). These
e non-native have the capacity to
e species h
spread quickly,
q take over open ground and eliminatte most othe er surroundding plant
species.. None of these species is mentioned by Prratt (1986) o or COSEW WIC (2000),
indicatin
ng that theirr presence is a recent occurrencee.
Crown Vetch
V formss a low grouund cover that carpetss open sand d. Because e it spreadss
quickly and
a has ten nacious roo ots, it is freq
quently plan
nted in highhway constrruction projects
to preveent erosion. According g to COSEW WIC (2012a a), in 2011 tthis speciess had alrea ady
succeed ded in covering up mos st of the oppen sand paatches in thhe small pra airie remnant
where Slender
S Bus
sh-clover is found. Spotted Knap pweed is kn nown to be h highly invassive
due to itts allelopathhic effects (secreting
( to
oxins from its roots intto the soil). It was liste
ed as
rare in th
he vicinity of
o the Slend der Bush-clover plantss. Autumn Olive is a fa ast-growing g
woody species
s thatt is presentt in the habitat. It has the capacitty to grow ttall and sha ade
out shorrter plants.
Historica
al threats
In the pa
ast, ATV an nd dirt bike use occurrred near the e Canadiann Slender Bush-clover
subpopu ulations (Prratt 1986). All-terrain vehicle
v usee can be a tthreat if it da
amages or
breaks plants
p and causes
c rutting and dissplacement of soil. Ho owever, distturbance fro om
ATVs prrobably also o contribute
ed to mainta aining the e exposed gro ound the sp pecies
requiress. All terrain
n vehicles and
a dirt bike es are no lo onger permmitted in the protected
parks wh here Slender Bush-clo over occurs s. This has eliminated the threat of damage e to
Slender Bush-clove er plants bu
ut it has also removed a factor tha at helped to o maintain
suitable habitat in the
t absence e of naturall disturbancce. Reinsta ating ATV u use is certainly
not reco
ommended, but the iss sue is mentioned here to show that light leve els of some
e
types off human dis sturbance may
m be bene eficial, altho
ough strikin
ng the corre ect balance
e
where no harm is done
d may be
b difficult.
1.7 Knowledg
K ge Gaps
Whetherr Slender Bush-clover
B is still pres
sent and via
able in the sseed bank at Tallgrasss
and Blac
ck Oak Herritage Parks
s is a knowledge gap tthat must b be filled in o
order to kno
ow if
10Recovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
these tw
wo sites (wh here live Sleender Bush h-clover plants have no ot been see
en recently) still
require recovery
r effforts. In ad
ddition, the processes needed to allow Slender Bush-
clover plants to be successfully re-establlished from the seed b bank are noot known.
Researcch to fill these gaps ge enerally requires takingg soil coress and germiinating all
seeds present in a controlled environmen nt.
Many otther knowle edge gaps need
n to be filled
f to guid
de recoveryy for the Ojjibway Parkk
occurren
nce and possibly for th he other twoo sites. These include e limited unnderstanding of:
thhe viability of
o the occurrence;
thhe frequenc cy and intennsity of burning that co ould be benneficial for h
habitat
maintenance
m e and improovement;
productivity (i.e., amount of seed sets and effe ects of wea
ather);
seed viability y and germmination rate
es;
genetic uniq queness and d possible effects
e of in
nbreeding;
availability of
o pollinators and degre ee of reliannce on self-fertilization versus cro
oss-
pollination;
current rates s and distan
nces of seeed dispersa al and availa
ability of an
nimal vectorrs;
and
thhe severity of the threaat from inva
asive specie es as well a
as the mechanism of tthe
th
hreat (e.g., shading, coompeting foor pollinatorrs, allelopathy, etc.).
The locaation and heealth of any y transplantted occurre
ences would
d also be useful to kno
ow
to assistt with poten
ntial future restorations
r s.
1.8 Recovery
R Actions Completed or Underway
All subpopulations of Slender Bush-clove er are within n parks tha
at are manaaged by thee City
of Windssor. No mo otorized vehhicles are allowed,
a so the threat oof damaged d or broken
n
plants and habitat degradation
d n from ATV Vs and dirt bbikes has bbeen eliminaated. In
addition, controlled
d burning is done in Ojibway Parkk, Tallgrass Prairie Heritage Parkk,
Ojibwayy Prairie Pro
ovincial Natture Reservve, and Sprring Garden n Natural Area, althoug
gh
the frequ
uency and intensity off burning in Slender Bu ush-clover habitat probbably needs to
be adjussted to ensuure burning
g actually coontributes tto the on-gooing mainteenance of
suitable habitat andd possibly provides
p ne
ew areas foor colonizatiion. Invasivve Crown
Vetch annd Autumn Olive have e been remo oved period dically by hand at the Ojibway Pa ark
Slender Bush-clove er site (P.D. Pratt, pers
s. comm. 22012).
In 2005, the Tallgra ass Recove ery Team produced the e draft Natiional Recovvery Strateg gy
for Tallg
grass Comm munities of Southern
S Ontario
O and Associated d Species a at Risk
(Ambros se and Waldron 2005)). The overrall goal of tthe plan wa as to recove er, reconstrruct,
and conserve a rep presentative e network of
o tallgrass communitie es, along wwith the full
complem ment of plan nt and animmal species that inhabiit these diveerse ecolog gical
commun nities. This strategy co overed 1388 plant speccies and 45
5 animal spe ecies that a are
rare or at
a risk, all off which are restricted to
t or assocciated with ttallgrass eccosystems.
Slender Bush-clove er is one off these speccies. While
e most recoovery effortss have sincce
11Recovery Strategy for the Slender Bush-clover in Ontario
shifted to working on species individually, this plan brought a lot of attention to the
benefits of recovering the ecosystem as a whole in order to improve the situation for
many species together. There are still several multi-species recovery plans being
developed and implemented from this group of species.
From 1985 to at least the mid-1990s, Slender Bush-clover was grown in gardens at the
Ojibway Nature Centre using seeds from the Tallgrass Park site (COSEWIC 2000, R.
Ludolph, pers. comm. 2012). The plants were planted out by the Rural Lambton
Stewardship Network as part of restoration work in the historical range of tallgrass
prairie. However, the main location where plants were successfully growing was
destroyed in a storm and information on any other locations has been lost. The species
is reportedly easy to grow and is good for attracting wildlife (R. Ludolph, pers. comm.
2012). A few plants still survive in the garden at the nature centre (P.D. Pratt, pers.
comm. 2012).
The Ojibway Prairie Complex, which consists of several parks, has been well studied
and botanized, so the area is well known and has been searched intensively without
finding additional sites for Slender Bush-clover. Furthermore, many other Ontario
prairie sites have also been well studied and searched for species at risk, and Slender
Bush-clover has not been found. This includes Walpole Island (Walpole Island Heritage
Centre 2006). The species also has not been found during new field work in the
corridor of the Detroit River International Crossing (Canada-U.S.-Ontario-Michigan
Border Transportation Partnership 2009), in which several new populations of other
species at risk have been discovered (G.E. Waldron, pers. comm. 2010, P.A. Woodliffe,
pers. comm. 2010). Thus, it is rather unlikely that additional populations of Slender
Bush-clover will be found.
12Recovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
2.0 RECOVER
R RY
2.1 Recovery
R Goal
The reco overy goal is to mainta
ain the abundance and d distributio
on of growinng plants off
Slender Bush-clove er at Ojibwaay Park at current
c or g
greater leve els by reduccing threatss,
and if the species is extant in the seed ba
ank at the oother two subpopulatio ons, to
increasee the numbe er of growin
ng plants present therre to pre-19995 levels.
Rationalle for Recov very Goal
First, two of three known
k subp
populations s of Slenderr Bush-clovver appear tto have bee en
lost to habitat degraadation. Th herefore, re
ecovery mu ust focus onn maintaininng the last
remainin ng location where live,, growing plants of thee species arre present. Second, th he
known historical
h dis
stribution off Slender Bush-clover
B r in Canadaa includes oonly the
Ojibway y Prairie Complex in Windsor
W and a site nearr Leamingto on where th he species has
not been n seen sincce 1892. Th herefore, re maintaining the current
ecovery willl focus on m
distribution in the Ojibway
O Pra
airie Comple ex. Finally,, whether th
here is a via
able seed bbank
of Slendder Bush-clo over has too be determined before e recovery ccan be con nsidered forr
Tallgrass and Black k Oak Herittage Parks..
Given thhe small population siz ze and extre emely limite
ed distributtion, it is unlikely that
recovery y will ever result
r in dow
wnlisting off this specie
es. Still, ha
alting habitaat loss may
result in stable or even
e somew what expanded popula ations which h might req quire less
attentionn to ensure their persisstence.
2.2 Protection
P n and Rec
covery Objectives
O s
To meett the recoveery goal, the
e protection
n and recovvery objectiives for Sle
ender Bush--
clover are as follow
ws:
Table 3. Protection
n and recov
very objectives
No. Protection
P or Recovery Ob
bjective
1 Maintain
M or im
mprove habita
at suitability att the three ex isting sites.
2 Reduce
R prese
ence of invasive species att the three exxisting sites.
3 Fill
F knowledge
e gaps.
4 Increase popu
ulation size an
nd extent if de
eemed feasib
ble.
Note tha
at the know wledge gap regarding the seed ba ank must be
e filled (Objective 3)
before itt will be kno
own if Objec
ctives 1, 2, and 4 shou
uld be applied to the T
Tallgrass an
nd
Black Oak Heritage e Park sites
s.
13Recov
very Strategy for the
t Slender Bush
h-clover in Ontarioo
2
2.3 Appro
oaches to Re
ecovery
T
Table 4. Appro
oaches to reco
overy of the Slender Bush-clover in Ontario
o.
Threats or
Relative Relative Recovery
Approach
A to Recovery K
Knowledge Gaps
s
Priority Timeframe Theme
Addressed
1. Maintain
n or improve habitat suitability at the three existing sites.
Critical Short-term Management
M 1.1 Assess type of habitat improv vement actions thhat are Habita
at degradation orr loss
and needed and appropriate for each
e of the three ssites.
Stewardship
S These may include burning, cutting
c back vegeetation,
scraping, rak
king or other actio
ons.
Critical Short-term Management
M 1.2 Assess potential positive or negative
n impacts oon Habita
at degradation orr loss
and other rare sp
pecies present in the same habitatt from
Stewardship
S habitat impro f Slender Bush -
ovement actions for
clover.
Critical Ongoing Management
M 1.3 Plan and exe ecute appropriate
e actions to improove Habita
at degradation orr loss
and habitat at ea
ach site.
Stewardship
S -- Search forr partners and vo
olunteers to help w
with
labour.
Necessary Ongoing Monitoring
M and 1.4 Monitor resu
ults of 1.3. Habita
at degradation orr loss
Assessment
A
Necessary Ongoing Management
M 1.5 Based on 1..4, plan next actio
ons. Consider Habita
at degradation orr loss
and stewardship frequency an
nd intensity at wh
hich action is requuired.
2. Reduce
e presence of inva
asive species at the
t three existing sites.
Critical Short-term Management
M 2.1 Assess best method to reduc ce presence of thee Invasiive species
and invasive spe ecies for each of the three sites. C
Consult
Stewardship
S current litera
ature for best mannagement practicces.
Critical Short-term Management
M 2.2 Assess potential positive or negative
n impacts oof Invasiive species
and invasive speecies removal on other
o rare speciees
Stewardship
S present in the same habitat.
14Recovery Strategy for the Slender Bush-clover in Ontario
Threats or
Relative Relative Recovery
Approach to Recovery Knowledge Gaps
Priority Timeframe Theme
Addressed
Critical Short-term Management 2.3 Plan and execute appropriate actions to reduce Invasive species
and invasive species presence.
Stewardship -- Search for partners and volunteers to help with
labour.
Necessary Ongoing Monitoring and 2.4 Monitor effects of 2.3. Invasive species
Assessment
Necessary Ongoing Management 2.5 Based on 2.4, plan next actions. Consider frequency Invasive species
and and intensity at which action is required.
Stewardship
3. Fill knowledge gaps.
Critical Ongoing Research 3.1 Plan and conduct research on seed bank of Slender Whether a viable seed bank
Bush-clover. is present
-- Search for partners to conduct research. How to bring Slender Bush-
clover back from seed bank
Beneficial Long-term Research 3.2 Plan and conduct research on other knowledge Population viability and
gaps as funding and partners become available. productivity
Seed viability and
germination
Genetics
Pollinators
Dispersal rates and
distances
Severity of threats
Location and health of
transplanted populations
4. Increase population size and extent if deemed feasible.
Necessary Long-term Management 4.1 Establish new populations as feasible to prevent All threats
extirpation of the species due to stochastic events
and as a precaution in case of failure to manage
current threats.
15Recovery Strategy for the Slender Bush-clover in Ontario
Threats or
Relative Relative Recovery
Approach to Recovery Knowledge Gaps
Priority Timeframe Theme
Addressed
Beneficial Long-term Management 4.2 Pending outcome of 1.4, conduct recovery actions to Limiting factor: small
increase presence of Slender Bush-clover at all population.
three sites.
Beneficial Long-term Management 4.3 Pending outcome of 3.1, conduct recovery actions to Limiting factor: small
increase presence of Slender Bush-clover from seed population.
bank.
16Recovery Strategy
S for th
he Slender Bu
ush-clover in O
Ontario
Narrative to Support Approach hes to Recoovery
All recovvery actions for Slender Bush-cloover need to o be carefu
ully assesse ed and plannned
before being
b carried out. This
s is to ensure that actio
ons do not harm the e existing smaall
population of Slend der Bush-clover or any y of the othe
er species at risk or ra
are speciess that
are pressent in the same
s habita
at.
Howeve er, most other species present wo ould probab onal clearing
bly benefit ffrom additio
and opeening up of the habitat (P.D. Prattt, pers. commm. 2012, S S.R. Brinker, pers. com mm.
2012), and
a staff at Ojibway Prrairie are already takin ng care to p
protect fire-ssensitive
species at risk during burning (P.D. Prattt, pers. commm. 2012). However, best
manage ement practtices (BMPs s) for invasive-speciess control alsso need to be conside ered
during re
ecovery woork to keep invasives from being ffavoured byy habitat cle earing. To
prevent spreading the invasivees, it is like
ely that seve
eral types oof recovery actions wo ould
need to be done in combinatio on (for exam mple, burning followed d by herbiciide use, or
clipping of shrubs followed
f by burning).
Althoughh the Canadian popula ation is veryy small, witth recovery actions, the prognosiss for
Slender Bush-clove er could be very positive. In Illino ois, efforts tto recover a similar
species,, Prairie Bush-clover (L Lespedeza a leptostachhya—threattened in the e U.S.), havve
includedd the use off fire, herbic
cide and gra azing by bisson to redu uce compettition from
grasses and other plants. Pre eliminary annalyses sho ow these tre eatments hhave resulteed in
an increase in seed dling production, an increase in n number of in ndividuals o
overall, and
d in
plants th
hat are morre robust (P P. Vitt, pers.. comm. 20012, Chicag go Botanic G Garden 201 12).
As a preecaution, it would
w be beneficial to
o establish ssome plantings of Slen nder Bush-
clover in
n locations separate
s fro
om the currrent patch tto ensure th
hat the spe ecies is not
extirpate
ed in case of
o an accide ental event, such as a storm. Th he few plantts in the gaarden
bed at th
he Ojibway Nature Ce entre could be augmen nted to ensuure a stable e garden
population. Slende er Bush-clover is listed
d on Schedule 1 of the e ESA as en ndangered only
within Olibway
O Parkk, Black Oaak Heritagee Park and T Tallgrass H
Heritage Park, so the
plants would
w not haave legal prrotection els
sewhere. T Therefore, it might be advisable tto
establish
h an additioonal restoraation populaation somew where within one of th hese parks to
ensure the
t plants would
w be prrotected. Relocation
R o
of the restorration sites where the
species was plante ed in Lambtton County would also o be beneficcial to see iff any restorred
populations of Slen nder Bush-c clover havee survived.
2.4 Area
A for Considera
C ation in Developin
D ng a Habiitat Regulation
Under thhe ESA, a recovery
r strrategy mus st include a recommen ndation to th
he Minister of
Natural Resources on the area that shou uld be consiidered in de eveloping a habitat
regulatio
on. A habita
at regulation n is a legal instrumentt that presccribes an arrea that willl be
protecte
ed as the haabitat of the
e species. The
T recomm mendation p provided beelow by thee
author will
w be one of o many sou urces cons sidered by th
he Ministerr when deve eloping the
habitat regulation
r for
fo this spec cies.
17Recovery Strategy for the Slender Bush-clover in Ontario
In establishing the area to be prescribed as habitat in a regulation, several
considerations need to be mentioned.
First, although seeds of Slender Bush-clover are known to remain viable for decades, it
is unknown whether Slender Bush-clover is still viable in the seed bank at the Black Oak
and Tallgrass Heritage Park sites. Therefore, it is recommended that all sites where
Slender Bush-clover has been observed in the Ojibway Prairie Complex come under a
habitat regulation even if no live plants are present, until this knowledge gap is filled or
until a 50-year time limitation has passed (see #4 below).
Second, the habitat of Slender Bush-clover must have periodic disturbance in order to
remain suitable. This disturbance may come from several different types of activities or
processes including some types of human usage. Therefore, it is recommended that
legal regulation and protection of habitat should not cause the exclusion of all human
activities from the regulated area.
Third, the current habitat of Slender Bush-clover occurs within the recognizable ELC
types, Dry Black Oak Tallgrass Savannah or Dry Black Oak Tallgrass Woodland.
However, suitable habitat is only some small open patches within the savannah or
woodland matrix, so the habitat required is much smaller than the entire ELC vegetation
type polygon. Thus, ELC vegetation type is not a precise enough guide to prescribe
habitat.
Finally, although dispersal habitat is an important consideration for recovery, for Slender
Bush-clover it is not possible to base the size of the habitat to be prescribed on
dispersal distances. Dispersal in animal or bird feces is unpredictable, and the
distances covered by these vectors may be quite large, even on the order of kilometres.
Therefore, it is recommended that habitat be prescribed as follows:
1) At Ojibway Park, where live Slender Bush-clover plants continue to be observed, it is
recommended that the regulated habitat include the entire opening in which the plants
occur, as well as a protective zone of 50 m around the outside of the open area,
including any disturbed, human-made components such as scraped areas since light
soil disturbance may be helpful to the species. Should any suitable openings extend
beyond the 50 m, it is suggested that all of this open area also be prescribed. For this
prescription, "open" or "opening" may be defined as the area in which total tree cover is
less than 25 percent, with ground dominated (greater than 50%) by herbaceous plants,
shrubs or exposed soil, and not shaded by trees. These criteria are consistent with the
ELC characteristics of tallgrass prairie and cultural meadow (Lee et al. 1998). The
boundaries of the opening at Ojibway Park would be the point at which tree cover
becomes continuous and the ground too shaded. The exact boundary line of the
Ojibway Park opening is probably best assessed and mapped in the field.
A distance of 50 m has been shown to provide a minimum critical function zone for the
maintenance of microhabitat properties, such as light, temperature, litter moisture, vapor
18You can also read
