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Few Flowered Clubrush/Bashful Bulrush

BACKGROUND

8.  Species Information

 

Date of Assessment:             May 2000

Common Name:                     Bashful Bulrush

Scientific Name:                    Trichophorum planifolium (Sprengel) Palla

COSEWIC Status:                 Endangered

Reason for Designation:       More that 50% decline over the past decade of the few remaining populations due to habitat destruction and alteration within its two remaining areas of occurrence.

Canadian Occurrence:           ON

COSEWIC Status History:   Designated Special Concern in April 1986. Status re-examined and designated Endangered in May 2000. Last assessment based on an update status report.

8.1  Species Description

Few-flowered Club-rush/Bashful Bulrush is a perennial herbaceous sedge with short (10-40 cm), erect, grass-like leaves, which form small clumps.  However, during seed dispersal in July and August, the leaves and culms become flattened and matted on the forest floor.  Each clump produces flowering spikes in the spring, just as its leaves are beginning to lengthen and prior to the emergence of tree leaves.  The spikes are triangular in cross section, 10-20 cm high.  The flowers are not showy, with only a small solitary spike being produced at the end of each stalk.  They have no petals, and the stamens and stigmas dangle outside the flowers for wind pollination.  The leaf sheaths at the base of the plant are weathered, shredded and light-brown to reddish-brown.   

Until recently, this species has been referred to as Scirpus verecundus Fernald. However, based on embryological, anatomical, and morphological data the genus Scirpus sensu lato has been found to contain several distinct, and only distantly related, genera (for a review see Strong, 1994).  Scirpus sensu lato species with a single terminal spikelet with a scale-like bract are now referred to as Trichophorum Persoon. This treatment is widely accepted in Europe, and is used in Flora of North America (Crins, 2002).

Common names are not often applied to sedge species, but this one has several.  COSEWIC lists this species as Bashful Bulrush, the Committee on the Status of Species at Risk in Ontario (COSSARO) lists it as Few-flowered Club-rush and Bashful Bulrush, and it is also known as Shy Bulrush.  Bashful Bulrush and Shy Bulrush are probably recent creations, the product of a direct translation of Scirpus verecundus.  In light of the generic revision of Scirpus sensu lato it would be appropriate to reserve the name bulrush for the robust wetland species in the new segregate genera Schoenoplectus, Bulboschoenus, and Scirpus s.s..  Species in the genus Trichophorum have been consistently called club-rushes, and that treatment is followed here.

9.  Distribution

9.1  Global range

Few-flowered Club-rush/Bashful Bulrush occurs throughout north-eastern North America, from Vermont south to Virginia, west to Missouri (Crins, 2002).  There is some question as to the validity of two records from Maine.  One of the records was based on a misidentified collection of Trichophorum clintonii, and the voucher for the other record has not been located (Haines pers. comm.).  The southern Ontario populations represent the northern limit of the global distribution.

The entire global distribution of Few-flowered Club-rush/Bashful Bulrush is presented in Figure 1.  This map has been compiled from previously published distribution maps, internet databases, and personal communications with American botanists (Haines per. comm., 2001; McAvoy, 2001; Sargent pers.comm., 2001; Kentucky State Nature Preserves Commission, 2000; Magee and Ahles, 1999; Maryland Wildlife and Heritage Division, 1996; Eaton, 1987; Wherry et al., 1979; Mohlenbrock and Ladd, 1978; Strasbaugh and Core, 1978; Stone, 1973; Braun, 1967; Steyermark, 1963; Massey, 1961; Zenkert, 1934; House, 1924).  Some of these references are quite old, and report records that have not been recently verified.  Other references do not include county information, so only vague regional records can be inferred.  The distribution map prepared by Crins for the Flora of North America (FNA) is also included in Figure 1.  Note that in publication this map was simplified to reflect only the state by state presence of Trichophorum planifolium (Crins, 2002).

Figure 1.  Global Distribution of Few-flowered Club-rush/Bashful Bulrush

Figure 1.  Global Distribution of Few-flowered Club-rush/Bashful Bulrush

9.2  Canadian range

The only occurrences of this species in Canada are in southern Ontario. There are two known locations (Figure 2): Royal Botanical Gardens’ Cootes Paradise Nature Sanctuary in Hamilton (eight extant occurrences and two historic records) and Rouge Park in Toronto (one potentially extant occurrence and one historic record). 

Figure 2.  Canadian Distribution of Few-flowered Club-rush/Bashful Bulrush

Figure 2.  Canadian Distribution of Few-flowered Club-rush/Bashful Bulrush

9.3  Percent of Global Distribution inCanada

Canada comprises less than 1% of the species’ global range.

9.4  Distribution Trend

The Canadian range of this species has remained roughly steady (two sites).  However, only one plant was found in Rouge Park in 2001 and none were found in 2005.  Few-flowered Club-rush/Bashful Bulrush may be extirpated from this location, but additional surveys are required to confirm this. 

10.  Population Abundance

For the purposes of this document, “plant” is defined as a grouping of stems which is separated from other such groupings by at least one centimetre (see O’Hara, 2001).  This operating definition may be revised upon the completion of ecological and genetic investigations (see Section 3).

10.1  Global Range

Few-flowered Club-rush/Bashful Bulrush is globally secure to apparently secure (G4G5), but rare along the margins of its distribution in Vermont (S1), Maryland (S2S3), Ontario (S1), Missouri (S3S4), Kentucky (S1?), West Virginia (S1), and Delaware (S2).  It is uncommon in New Jersey (S4) and is considered historic in Illinois (SH) or District of Columbia (SH).  All Nranks and Sranks come from NatureServe (2005).  It is listed as Endangered in Vermont (VFWD, 2005), Ontario (OMNR, 2005) and Kentucky (Kentucky State Nature Preserves Commission, 2000).  Rare species tracking data for Few-flowered Club-rush/Bashful Bulrush are not available in the rest of its range – it is reported without an assigned status (SNR) in Connecticut, Maine, Massachusetts, New York, Ohio, Pennsylvania, Rhode Island, and Virginia (NatureServe, 2005).

10.2  Canadian Range

Few-flowered Clubrush/Bashful Bulrush is nationally critically imperilled (N1) (NatureServe 2006).  Field work completed in 2001, located 1633 plants from eight sites in Hamilton, however, only one plant (with 40 stems) was located in Rouge Park in 2001 and none were found in 2005.  A second Rouge Park population is suspected to have been extirpated as there were several unsuccessful searches in the 1990s (White, 2000).  It could not be located by the primary author in 2001, despite intensive searches in the vicinity of the original record.  Census data for each of the existing and historic Canadian records of Few-flowered Club-rush/Bashful Bulrush are presented in Table 2.

10.3  Percent of Global Abundance inCanada

Less than 1% of the global abundance occurs in Canada .

10.4  Population Trend

Significant declines are documented in the abundance of the Rouge Park populations.  One Rouge Park population consisted of hundreds of flowering culms in 1984 (Crins, 1989).  Varga et al. (1991) confirmed its persistence in comparable numbers.  It was not located during 1997, and only a single “tuft” was found in 1999 (White, 2000).  A single plant was located in 2001 (Smith, 2001).  Field work during 2005 failed to find it at this location.  

The other Rouge Park population consisted of a single “tuft” in 1981.  Royal Botanical Gardens staff returned to the location of the original report in 2001, but did not find any Few-flowered Club-rush/Bashful Bulrush.  Several other searches have failed to locate this population, and it is presumed extirpated (White, 2000).

It is difficult to determine the status of the Cootes Paradise Populations based on current data.  Four of the Hamilton populations numbered several hundred to thousands of fruiting culms in 1984 (Crins, 1989).  A fifth Hamilton population consisted of eight clumps of five to 30 flowering culms each.  White (2000) reported significant declines, being unable to locate three of these populations, and observing more than a 50% reduction in numbers at another two populations in 1999.  However, subsequent surveys conducted by Royal Botanical Gardens staff documented large populations at Cootes Paradise in 2000 and 2001 (O’Hara, 2001 and new data presented here).

The discrepancies between the data presented in Table 2 by Smith (2001) and those presented by White (2000) highlights the challenges in assessing the status of Few-flowered Club-rush/Bashful Bulrush.  This species is extremely inconspicuous. In addition, it is associated with gap-phase succession [1].  As a result, even under optimum conditions the persistence of Few-flowered Club-rush/Bashful Bulrush at any given location may be naturally limited, with long-term survival dependant upon the colonization of new sites.  Ongoing monitoring efforts should take this into account: in addition to monitoring existing populations, regular surveys to locate new populations should be conducted.

Table 2.  Summary of Reports of Historical and Extant Few-flowered Club-rush/Bashful Bulrush Sites

SiteEO IDTamsalu's CollectionsCrins 1989 White 2000 Smith 2001Varga, Davies, Miller 2005Vouchers
Cootes 113026 Not located First record, no population estimate Not located NS1, 6 plants N/A HAM 1329
Cootes 23100 First record 1955, "sparsely grouped" "large colony, about 100's of culms" Not located NS2, 18 plants N/A HAM 1327 HAM 1333 HAM 1335
Cootes 313027 First record 1955, "common" Not located Not located Not located N/A HAM 1331
Cootes 413027 First record 1955, "sparse" Not located Not located Not located N/A HAM 1332
Cootes 513027 First record 1958, "rare" "100's of culms, about 10 large clumps" Not located SS1, approximately 1150 plants N/A HAM 1328 HAM 1336 HAM 11323
Cootes 613027 Not located Not located Not located First record, SS2, 4 plants N/A None
Cootes 713027 Not located Not located First record, 1.5m x 1.5m patch of 10 clumps, each with about 10-20 flowering stems SS3, 81 plants N/A None
Cootes 813027 Two 1957 collections, HAM 1330 and HAM 1334, could be from either this location or the next. "Sparsely grouped" Not located Not located First record?, SS4, 171 plants N/A HAM 1330 HAM 1334
Cootes 913027 See above Not located Not located First record? SS5, 92 plants N/A None
Cootes 1013027 Not located Not located Not located First record, SS6, 111 plants N/A HAM 11319
Rouge 13098 N/A "Hundreds of flowering culms" "One small clump" 1 plant, 40 stems Not located None
Rouge 23101 N/A A single clump first recorded in 1981, not located in 1984. Not located Not located N/A None

Sources: Collections by Bill Crins, Paul O'Hara, and Aleksander Tamsalu in the Royal Botanical Gardens Herbarium (HAM); fieldwork completed by Steve Varga, Barb Davies and Gavin Miller in 2005, Tyler Smith in 2001; Varga et. al, 1991; Crins, 1989; O’Hara, 2001; White, 2000.

11. Biologically Limiting Factors:

The ecology of Few-flowered Club-rush/Bashful Bulrush is poorly understood.  Crins (1989) observed that all Canadian populations occur in the vicinity of forest canopy gaps.  This association suggests that gap-phase succession is likely responsible for producing and maintaining Few-flowered Club-rush/Bashful Bulrush habitat.  If this is the case, metapopulation dynamics that are controlled by gap dynamics may be more important than individual population trends in the long term.  No mechanism for long distance seed dispersal has been identified.  The relationships between gap creation, dispersal and colonization, seed bank and germination conditions, and demographic trends need to be elucidated.

12. Threats

Potential threats to Few-flowered Club-rush/Bashful Bulrush have been compiled from documents and individuals who are knowledgeable about the plant.  These threats are listed below, but none have been investigated empirically.  Basic biological studies need to be conducted (see Section 3) before these threats can be fully characterized, ranked and eliminated. 

Canopy closure due to succession and fire suppression, may pose the greatest threat to this species.  Crins (1989) suggested that the primary limiting factor in the establishment of new colonies appears to be the amount of sunlight reaching the forest floor through canopy gaps.  It is suspected that this is a contributing factor to the decline of Few-flowered Club-rush/Bashful Bulrush in Rouge Park and was identified as a threat to all eights sites in Cootes Paradise (O’Hara, 2001).

While moderate disturbance has been suggested as important in producing habitat for Few-flowered Club-rush/Bashful Bulrush, excessive disturbance has been identified as a threat.  Both natural (Coyote [Canis latrans] dens) and anthropogenic (hiking trails) disturbances (often resulting in erosion) were reported as damaging populations by White (2000).

High rates of deer browse were noted in Rouge Park during site visits in 2005 and may be a factor in its decline at that location.  This was also identified as a potential threat to three sites in Cootes Paradise (O’Hara, 2001).

Competition from native (Carex pensylvanica, Crins, 1989) and introduced (Lonicera spp., White 2000) plants was also suggested as a potential threat.

During the 2001 field season, fungal infection and lepidopteran herbivory destroyed some fruit-clusters in the Cootes Paradise populations.  The extent and significance of these factors are not known.

13. Habitat Identification

13.1 Habitat Needs

Few-flowered Club-rush/Bashful Bulrush is found in open-canopied deciduous and mixed forest with few shrubs in the understory and excellent drainage.  In Ontario, the plants are found on warm, slightly disturbed sites with associated tallgrass habitat.  Common associates are White Oak (Quercus alba), Black Oak (Quercus velutina), and White Pine (Pinus strobes). Herbaceous associates include Pennsylvania Sedge (Carex pensylvanica), Bellow-beaked Sedge (Carex albicans), Oval-leaved Sedge (Carex cephalophora), Longstalk Sedge (Carex pedunculata), Broad-leaved Sedge (Carex platyphylla), Hairy Woodrush (Luzula acuminata), Large-leaf Wood-aster (Eurybia macrophylla), and Bluestem Goldenrod (Solidago caesia).

The putative gap-phase specialization of Few-flowered Club-rush/Bashful Bulrush has serious implications for long term habitat requirements.  It may be determined that individual populations suffer natural extinctions as canopy gaps close.  If this is the case the persistence is dependent upon the ability of Few-flowered Club-rush/Bashful Bulrush to colonize new gaps as they form.  Effective stewardship will therefore require a sound understanding of dispersal and seedbank dynamics for this species.

13.2 Critical Habitat

The Species at Risk Act (SARA) defines critical habitat as "the habitat that is necessary for the survival or recovery of a listed wildlife species”.  Extensive information is required to define critical habitat and the following is only a portion of what is believed to be the critical habitat for Few-flowered Club-rush/Bashful Bulrush.  At this time, critical habitat will only be described to the extent possible and will be refined as additional information is acquired. 

The survival of Few-flowered Club-rush/Bashful Bulrush is contingent on the protection of its occupied habitats in Cootes Paradise and Rouge Park.  Critical habitat for Few-flowered Club-rush/Bashful Bulrush is being identified, to the extent possible, in the Recovery Strategy, and includes: (1)  the eight sites of occupied habitat that have been identified at Cootes Paradise, six on the south shore and two on the north shore.  These occupied habitats are contained within Dry-Fresh Oak-Red Maple Deciduous Forest Type and Dry Black Oak-White Oak Tallgrass Woodland Type as described by the Ecological Land Classification (ELC) for Southern Ontario (Lee et al. 1998); and, (2)  one site of occupied habitat that is located in the Rouge Park within Dry-fresh Mixed Oak Deciduous Forest Type.  All of these sites are warm, well-drained slopes, usually subject to slightly higher-than-average light levels, due to tree fall, proximity to trail, or steep slope (Crins, 1986). Further studies are needed to more fully identify the extent of critical habitat required to achieve long-term survival of the species and are identified in Section 13.4.

13.3 Examples of Activities that are Likely to Result in Destruction of the Critical Habitat

The primary activities that will likely result in destruction of critical habitat are:

  • Trampling from the adjacent recreational use of trails and the creation of new trails.

13.4 Schedule of Studies

Further study is required to determine if additional critical habitat is required for the recovery of Few-flowered Club-rush/Bashful Bulrush.  Very little is known about the biology and ecology of this species and Section 3 identifies many of the remaining questions that research efforts could help answer.  Table 3 draws from this list to specifically address the research activities which will help determine if and where additional critical habitat is required for the recovery of Few-flowered Club-rush/Bashful Bulrush.  

Table 3.  Schedule of Studies

Description of Research Activity Expected Results

Start

Date*

Completion Date*
Update habitat mapping and assessment using Ecological Land Classification (ELC) for all sitesIdentify the ELC vegetation type and its extent for each population.April 2006Oct 2007
Complete a Population Viability Analysis (PVA).To determine population viability under current conditions and to help evaluate the number of individuals and amount of habitat required to attain viability.Nov 2008Mar 2009
Further define the abiotic and biotic habitat requirements for the species.To help identify potential critical habitat for population expansion if deemed necessary by PVA.April 2006Nov 2009

* These are tentative dates and may be modified as necessary.

13.5  Habitat Protection / Ownership

The habitat for the vast majority of the extant sites is protected under the private ownership of Royal Botanical Gardens in Cootes Paradise Nature Sanctuary. 

Rouge Park is publicly owned by the Toronto and Region Conservation Authority and managed under the direction of the Rouge Park Alliance.  The Park’s goal, as identified in Rouge Park’s Management Plan (1994), is “to protect, restore, and enhance the natural...values of the park in an ecosystem context...”.  Both sites of Few-flowered Club-rush/Bashful Bulrush are zoned as Nature Reserve in Rouge Park’s Management Plan.  The policies regarding this zoning include management for the continuation of natural processes, and limiting development to walking trails, cross country ski trails and wildlife viewing.

Few-flowered Club-rush/Bashful Bulrush is listed as Endangered under the Species at Risk Act and is regulated under Ontario’s Endangered Species Act.  This provides protection to the plant and its habitat.  Ontario’s Provincial Policy Statement also offers protection by not permitting development or site alteration in its significant habitat. 

14.  Ecological Role

This species is an understorey herb. Otherwise, no specific ecological roles are known for this species.

15.  Importance to People

The presence of this species could be capitalized upon by Royal Botanical Gardens and/or Rouge Park for ecotourism activities.  Its protection could influence the alignment of trail systems, access for wildlife viewing and forest management practices for both properties. 

16.  Anticipated Conflicts or Challenges

The inconspicuous nature of the species presents challenges in conducting field research.  Locating populations has proven to be difficult, and any surveys must be completed between late April and early June to be effective.

The pool of individuals with field experience to search for this species is limited given the difficulty in its identification.  There are individuals within the Guelph and Aurora District offices of the MNR  TRCA and at RBG with the requisite experience to continue to monitor and to search for new populations.  

This species is associated with gap-phase succession limiting the ability of the species to persist in any suitable or optimal habitats.  Vigilance is required to monitor known populations to record changes in the habitat.  Opportunities for the creation of new canopy gaps need to be pursued if this is not occurring naturally.

17.  Knowledge Gaps

17.1  Survey Requirements

The discovery of other populations in Canada could change the conservation priority of the species.  It would certainly improve our understanding of its ecology.  The inconspicuous nature of the plant has led several authors to speculate that it is likely under-reported (Crins 1989, Steyermark 1963, Strasbaugh and Core 1978).  Crins (1986) identified major river valleys of Western Lake Ontario as potential sites for further investigation.  Specifically, he named Jordan Valley, Grindstone Valley, Bronte and Oakville Creeks south of Highway 5, and Highland Creek. Maycock’s collection from Eastern Lake Ontario suggests that searches in appropriate habitat around Cornwall may be fruitful.

Several of these areas were searched in 2001, but no new records of Few-flowered Club-rush/Bashful Bulrush were discovered.  The Hendrie Valley Nature Sanctuary (Royal Botanical Gardens) portion of the Grindstone Creek was searched without success in both 2000 and 2001.  This area has very similar habitat to the occupied sites in Cootes Paradise.  It has now been searched intensively over several years, and it is unlikely that Few-flowered Club-rush/Bashful Bulrush could have been overlooked.  Further searching upstream of Royal Botanical Gardens property may prove more successful.  La Salle Park in Burlington was searched, as it has habitat comparable to the Cootes Paradise sites.  In addition, Royal Botanical Gardens staff spent half a day searching the slopes and rim of the Bronte Creek Valley in Oakville.

17.2  Biological/Ecological Research Requirements

Basic biological information is lacking for this species; background ecological, habitat and genetic research is thus essential for effective recovery planning (see Section 3). What little is known about its ecological relationships suggests that it could present several interesting conservation challenges.  After establishing the geographical distribution of the species through field surveys, demographic studies are critical in planning for recovery.  As outlined in Schemske et al. (1994), these studies would include three distinct stages:

1) Assessing the biological status of the species using quantitative demographic studies:

Are populations stable, declining, or increasing over time?

2) Identifying life history stages critical to overall population decline:

Can population decline be linked to a particular life history stage?

e.g. seedbank, seedling survival, seed-set, dispersal

3) Determining biological factors responsible for critical life history stage parameters:

What is limiting the success of the critical life history stage?

e.g. lack of genetic diversity, disturbance regime, missing disperser, climate change

Once completed, this research would enable the recovery team to establish appropriate goals with accompanying restoration actions.

17.3  Threat Clarification Research Requirements

The research outlined in Section 3 directly addresses threat clarification.  As described in that section, once threats have been identified, more detailed studies and specific recovery actions will be described in a Recovery Action Plan.  

18.  Ecological and Technical Feasibility of Species Recovery

Based on current knowledge of Few-flowered Club-rush/Bashful Bulrush, it is recommended that recovery of this species is technically and biologically feasible. 

The relationship between Few-flowered Club-rush/Bashful Bulrush and natural disturbances suggests that practical management practices could be found to protect and enhance Canadian populations.  Basic biological data need to be collected before these practices can be appropriately defined.

Ecological Land Classification (ELC, Lee et al. 1998) surveys have been completed for the populations at Cootes Paradise.  The results of the ELC survey show that all available habitats are not occupied in Cootes Paradise, and appropriate unoccupied habitat occurs in Hendrie Valley.

Quality habitat in Royal Botanical Gardens Nature Sanctuaries, and in Hamilton and Halton Regions generally, coincides with areas identified as tallgrass woodland remnants (Goodban et al. 1996).  Few-flowered Club-rush/Bashful Bulrush is not listed as a component of the tallgrass flora (Rodger 1998, Packard and Mutel 1997).  However, the conditions in dry-fresh tallgrass woodland communities correspond to those favoured by Few-flowered Club-rush/Bashful Bulrush: warm exposures, coarse well-drained soils, open understory, and occasional canopy gaps.  Habitat mapping for Rouge Park was completed in the late 1980s and is presented in the Ecological Survey of the Rouge Valley Park (Varga et al. 1991).  Updated mapping using current Ecological Land Classification standards would useful to assess the quality and availability of habitat in Rouge Park.

Open woodlands, tallgrass or otherwise, are becoming scarce in Hamilton and Halton (Goodban et al. 1996).  The open character previously maintained by a natural fire regime is being lost.  In the absence of fire, native and introduced forbs and shrubs are colonizing the understory.  This lowers the light levels reaching the ground, creating a cooler, wetter microclimate. As a result the availability of potential habitat for Few-flowered Club-rush/Bashful Bulrush is being reduced.

Prescribed burns or physical removal of shrubbery could be effective tools to restore open habitats.  A coordinated tallgrass woodland restoration program, incorporating these and other measures, would serve two related objectives.  Immediately, it would help protect the flora and fauna of this endangered habitat.  In the long term it could provide critical habitat for Few-flowered Club-rush/Bashful Bulrush (and also Hoary Mountain Mint (Pycnanthemum incanum), another endangered species that exploits forest gaps (Thompson 2000)).  Similarly, threats from human disturbance are manageable at the Cootes Paradise and Rouge Park locations (via exclosures or trail re-routing).

Successful ex situ propagation techniques have been identified.  Seeds collected from Cootes Paradise in 2000 were germinated after cold stratification in the Royal Botanical Gardens greenhouse.  17% germination was recorded in a test planting (5 out of 30 seeds germinated).  A total of 80 seedlings have been produced.  At the end of one season of growth most of the seedlings have four to six culms.  These seedlings will not be planted out until the need is firmly established and a scientific introduction strategy is developed.

19.  Recommended Approach / Scale for Recovery

The restoration of Few-flowered Club-rush/Bashful Bulrush would probably benefit other species such as those associated with tallgrass woodlands, according to the tallgrass communities recovery plan (Rodger 1998).  Recovery efforts for Few-flowered Club-rush/Bashful Bulrush should coordinate with this community recovery plan and the Hoary Mountain Mint recovery strategy since they share similar habitats and threats.  There may also be opportunities to coordinate efforts with the Rouge Park Management Plan and TRCA’s Natural Heritage Strategy.  Long-term recovery for Few-flowered Club-rush/Bashful Bulrush will require research directed at identifying threats and opportunities specific to this species.  Metapopulation dynamics may be critical in establishing the appropriate scale for recovery action.

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[1] Gap-phase succession refers to the dynamic ongoing process of regeneration that occurs in small forests openings.  These openings or gaps are continually created by the loss of single mature trees.  These sites become areas of increased regeneration and are eventually occupied by trees reaching into the canopy.