Department of Biology

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Open Access
Response of Vegetation to Grazing Pressure by White-Tailed Deer, Odocoileus virginianus: Progress report on studies carried out in l992 at Point Pelee and at other sites in Southern Ontario
(Biology Department, York University, 1993) Koh, Saewan; Bazely, Dawn
Open Access
Responses of Vegetation to Grazing by White-Tailed Deer, Odocoileus virginianus, Progress Report #2: Studies carried out from 1992-1993 at Point Pelee National Park and at other sites in Southern Ontario
(Biology Department, York University, 1994-06) Bazely, Dawn; Koh, Saewan
Open Access
Interactions between deer and vegetation in southern Ontario, Canada: Monitoring and restoration of overgrazed plant communities in Pinery and Rondeau Provincial Parks.
(Biology Department, York University, 1995-03) Pearl, David L; Koh, Saewan; Bazely, Dawn; Voigt, Dennis R; Tang, Maxine; Soo, Wyman
Executive Summary: One of the main goals of this report was to lodge a single record of our numerous research activities on deer-plant interactions in southern Ontario. Table 1 summarizes the project's components and illustrates its wide scope. Not all of the results from these studies are presented in this report; some results are in other reports, while some data, specifically that on stand composition, soil seed bank composition, and woody browse availability, still await analysis. With the large database that we have amassed, we are now well placed to accurately monitor and assess changes in plant communities as vegetation recovers following the deer herd reduction in Rondeau and to place the ongoing degradation of grazed vegetation at Pinery into both a spatial and historical context. In spring 1994 it was clear that there was more herbaceous vegetation at Rondeau than at any time since 1991. This rapid recovery in deer grazed areas was expected based on the results of exclosure studies. Preliminary results from our studies of plant community composition showed that the plant community at Rondeau changed following protection from deer grazing in 1991 and 1978 exclosures. In 1994, both the grazed and ungrazed sites at Rondeau were distinguished from the Pinery sites in having a higher percent cover and a greater abundance of herbaceous species, typical of a mature, undisturbed Carolinian forest (e.g. Viola spp.). However, in 1992 these same Rondeau sites were distinguishable from other less heavily grazed location in southern Ontario because they had a higher percent cover of grazing tolerant species (e.g. Aster spp.). We do not yet know whether the plant community will return to its condition before disturbance by deer grazing or whether the "recovered" community will be fundamentally different - only time will tell. In 1995 we will be analyzing data sets from Rondeau for 1991, 1992, 1994 and 1995 to determine how the plant community has changed with time. We had success with the use of plant species as indicators of overall vegetation recovery following grazing, although only two of the five species which we assessed were suitable. In addition to Trillium grandiflorum (Koh et al., 1995), Circaea quadrisulcata and Polygonatum biflorum were good indicators of grazing pressure and habitat protection at Rondeau. Plant sizes observed throughout the park were determined more by deer grazing, which imposes homogeneity across grazed sites, than by habitat variation (e.g. soil type). The three other candidates for indicator species did not respond to release from deer grazing pressure as well, and their heights appeared to be related more to other factors than deer grazing. In 1995 appropriate indicator species will be determined for Pinery. While some rare plants such as Showy Orchis flowered for the first time in years in Rondeau, in general we found that effective monitoring of the recovery of rare species within the park required greater effort than was possible from two or three individuals doing sporadic searches. Due to the many negative results (failure to find species) we must develop a stringent protocol for quantifying search effort. As a consequence, S. Koh, D. Bazely, and A. Woodliffe (OMNR) will be designing a protocol which accounts for search effort and will make use of the potential volunteer base from Rondeau's visitors. Exotic and invasive plant species are of concern in any habitat which has been released from strong grazing pressure. It appears unlikely that the lower grazing pressure at Rondeau will result in as wide a distribution of weedy, invasive species as at Point Pelee National Park (e.g. Alliaria officinalis) because of the robust seedbank which contains many native species (Koh & Bazely, 1994). The greater crown cover at Rondeau (Koh, pers. comm.), in contrast to Point Pelee which is more open, will not provide as suitable a habitat for these weedy species with respect to light availability. However, in disturbed areas within Rondeau (e.g. along roadsides) some weedy species appear to be spreading. Treatment and monitoring programs initiated in 1994 will continue for A. officinalis in 1995. Berberis thunbergii (woody exotic) may have spread throughout Rondeau due to their thorns which defend them against grazing. This species may be less competitive against native shrubs now that grazing pressure has been reduced. We recommend that treatment programs be continued, and monitoring programs be established for this species. Since a herd reduction has not taken place at Pinery and has only recently occurred at Rondeau, it is vital to have a comprehensive baseline dataset against which to compare continuing habitat degradation or recovery. Such a database is in the process of being created for the woody stand structure and woody-browse, and herbaceous plant communities in both Pinery and Rondeau. Each year, data collected from the parks over the duration of the project can be compared against this baseline to monitor changes over time and grazing pressure. A report after the 1995 field season will provide the first indication of what changes can be expected in the long-term recovery process.
Open Access
Impact of herbivory of white-tailed deer (Odocoileus virginianus) on plant community composition
(Association of Applied Biologists, Horticulture Research International, Wellesbourne, Warwick., 1996) Koh, Saewan; Watt, Trudy A.; Bazely, Dawn; Pearl, David L.; Tang, Maxine; Carleton, Terry J.
The woodland ground flora of permanent quadrats in dry, wet and mesic habitats in Rondeau Provincial Park, Ontario, Canada was recorded in 1992. This park is a premier example of Carolinian or deciduous forest, but is heavily grazed and browsed by white-tailed deer (Odocoileus virginianus) . Within each habitat type there were both grazed and year-old fenced plots. In addition, the flora was recorded in 14-year old deer exclosures in the woodland. The long-term ungrazed plots contained greater amounts of species characteristic of Carolinian woodland (e.g. Arisaema triphyllum and Trillium grandiflorum), whereas the grazed plots had higher levels of invasive weeds (e.g. Stellaria media and Berberis thunbergii ). These data provide a baseline against which recovery of ground flora may be assessed following the herd reduction which took place in winter 1993 . Over-grazing by deer is a problem also found in southern English woodlands where roe, fallow, muntjac and sika deer numbers have increased in recent years.
Open Access
Interactions between deer and vegetation in Southern Ontario: Monitoring and restoration of overgrazed plant communities in Rondeau and Pinery Provincial Parks
(Biology Department, York University, 1997) Bazely, Dawn; Carr, L W.; Koh, Saewan; Carnie, John; Greenberg, Amy; Isaac, Leigh Anne; Falkenberg, Nancy; Hunt, Andrea M.; Sykes, Catherine A.; Carleton, Terry J.; Voigt, Dennis R.; Carleton, S. M.
Executive Summary: 1. In 1994 the Science Technology Transfer Unit of the Ontario Ministry of Natural Resources initiated a 5-year project in collaboration with the Department of Biology, York University, Toronto, to monitor and assess southern Ontario forests affected by deer herbivory. 2. In 1995, we obtained the Cornell Ecology Detrended Correspondence Analysis (DECORANA) and Canonical Correspondence Analysis (CANOCO) computer programmes. These allowed multivariate analysis of changes in the herbaceous plant communities at Rondeau and Pinery Provincial Parks, as well as the relationship between these two parks and 8 other study locations. We have analysed Rondeau data for 1995 and compared 1992 to 1995. This period covered a 1993 herd reduction. Plant community composition changed significantly in grazed areas from 1992 to 1995, but did not change significantly over the same period in deer exclosures built in 1991. We concluded that we either missed a very rapid change that occurred in exclosures from 1991 to 1992 (we have the data to check this) or the overall composition of intensely grazed plant communities in Rondeau is very slow to change to pre-overgrazed conditions. In 1995, the plant community composition was significantly different between the Bennett and Gardiner exclosures, built in 1978, and the grazed areas and also the 1991 exclosures. We suggest that these differences may be due in part to the different shade conditions in these habitats. We also suggest that intense deer grazing has radically altered subcanopy light conditions, and has subsequently affected the recovery of herbaceous communities. We will be testing this hypothesis in 1997. If it is valid then herbaceous (understorey) plant communities may only recover when overstorey woody plant communities recover from the detrimental effects of deer grazing. 3. A range of species were found to be suitable indicators of grazing pressure and vegetation recovery at both Rondeau and Pinery Parks. Plants that survived deer grazing at Rondeau increased in height from 1994 to 1995. However, a 1996 study of Arisaema triphyllum by Dennis (1996) suggested that increasing deer numbers may again have started to have an adverse affect on this species. Plant heights need to be examined in 1997 in order to confirm these trends. 4. Exotic and invasive species are of concern in Rondeau and Pinery because of their ability to invade and dominate disturbed areas. Alliaria petiolata, Garlic Mustard, populations have expanded significantly in Rondeau from 1994 to 1996. The effectiveness of control programmes for Garlic Mustard, which were initiated in 1994, could not be evaluated due to the unusual population dynamics of Garlic Mustard in which plants go through alternate years of high and low flowering populations. 5. Berberis thunbergii, Japanese Barberry, is an exotic shrub common in Rondeau. If a removal policy for B. thunbergii is to be adopted, then the most effective method is cutting the bushes and then painting the stumps with herbicide. 6. The structure and composition of woody plant communities at Pinery and Rondeau Parks have been altered by intensive vertebrate grazing, resulting in lower shrub densities and the presence at both parks of unpalatable woody species. Intensively grazed sites such as Rondeau and Pinery had smaller trees (lower diameters at breast height - DBHs) than other forest locations. We suspect that there may be higher mortality rates of larger trees at Rondeau and in some Pinery habitats due to increased windthrow. This process could be initiated when intense deer grazing reduces the sub-canopy shrubs and saplings to the point where recruitment of saplings to the canopy does not occur. When recruitment declines, canopy gaps will increase in size, subsequently increasing the likelihood of windthrow of larger trees. In 1996, Catherine Sykes (M.Sc. student) revisited 1980 plots in Rondeau and found that in some of them over 50% of the large trees were gone and many of the smaller trees were also missing. These data, along with lower DBHs, suggest that regeneration rates at Rondeau are not high enough to fill existing canopy gaps. In addition, the relatively low shrub densities in Bennett and Gardiner exclosures indicate that recovery is proceeding slowly. Overall, these results are alarming because they suggest that the Rondeau forest will continue to decline as long as trees are no longer recruited to the overstorey. We strongly recommend that the loss rates of large trees and rates of creation of canopy gaps be monitored at Rondeau (this is included as part of our 1997 research programme), and that the impact of altered understorey light conditions on plant communities be assessed. This will indicate whether some form of drastic management intervention might be justified to replace and/or protect large trees. 7. Available woody browse (current annual growth - CAG) was sampled in Rondeau and Pinery in the Fall of 1994 and 1995. In both parks the availability of woody browse was extremely low in 1995 (< 1 g dwt CAG /m2), with the bulk of CAG from species traditionally considered to be less palatable to deer.
Open Access
Overgrazed Ecosystems: Do Plant Communities Recover?
(Parks Research Forum of Ontario (PRFO) Heritage Resources Centre University of Waterloo, Waterloo, Ontario, Canada, 1998) Koh, Saewan; Bazely, Dawn; Watt, Trudy A.
Large herbivores, such as white-tailed deer (Odocoileus virginianus), are major determinants of the structure and composition of forest plant communities. Previous studies of herbivory have examined plant community response by focusing primarily on diversity indices or single plant species. Few studies have shown whether statistically significant changes in species composition have occurred. In this study we used ordination analyses (DCA, CCA and RDA) to examine the effect of biomanipulations including exclosures and removal of deer on plant species composition and the dynamics of southern Ontario forests in the Canadian region of the North American Eastern Deciduous Forest or Carolinian Zone. In 1992, 1995 and 1996, plant communities in forest stands with high deer densities (50 deer/km2) were compared with adjacent plots closed-off to deer in 1978, 1991 and other long-term ungrazed sites. Stands where deer were reduced in 1993 from 10 to 50 individuals/km2 were also examined. Ordination showed that older exclosures were similar to ungrazed sites and dominated by native plant species. Both differed significantly from grazed sites, which were dominated by non-native species. Newer exclosures and stands where deer densities were reduced differed from both grazed and long-term ungrazed sites. This suggested an intermediate or alternate recovery trajectory with implications for management decisions about plant species conservation and reestablishment. Herbivore-mediated changes in light regimes at-the forest subcanopy may be a factor in preventing native plant communities in overgrazed sites from recovering and may also be determining the trajectory of some plant communities over time.
Open Access
Grazing impacts of White-tailed Deer or "Culling Bambi to save the forest"
(Heritage Resources Centre, University of Waterloo, 2000) Koh, Saewan; Bazely, Dawn; Timciska, M.
Large herbivores, such as white-tailed deer, can significantly determine the structure and composition of forest plant communities. In several National and Provincial Parks located on southwestern Ontario shorelines, deer overgrazing has been a major cause of habitat degradation. Few studies of herbivory have examined the link between herbivory-induced or mediated changes in environmental variables, and vegetation change. In this study we used ordination analyses (DCA, CCA) to examine the effect of changes in understorey light levels on plant communities in Rondeau Provinical Park and other Carolinian forests. In 1996, plant communities in forest stands with a past history of high deer densities (50 deer/km2) were compared with deer exclosures and other long-term ungrazed sites. Ordinations showed that older exclosures were similar to ungrazed sites and dominated by native plant species. Both differed significantly from grazed sites, which were dominated by non-native species. Newer exclosures and stands where deer densities were reduced differed from both grazed and long-term ungrazed sites, suggesting that these plant communities are following an intermediate or alternate recovery trajectory. Interestingly, despite the differences in plant community composition there were no significant differences in species diversity among treatments. Thus, measurements of diversity or species richness alone are inadequate descriptors of plant community change. From 1987-91 over 50% of trees were lost from permanent plots in Rondeau. The main reason is that deer overgrazing has prevented tree regeneration, causing increased understorey light levels. We suggest that in this more open forest, the normal recovery of native plant species is prevented, and the trajectory of some plant communities over time, may have been significantly altered. The major implication for park managers is that sustained deer herd reductions alone are not enough to ensure the recovery of vegetation - management for accelerated canopy closure may also be desirable.
Open Access
Restoration of Red Cedar Savanna Plant Communities in Point Pelee National Park
(Heritage Resources Centre, University of Waterloo, 2000) Falkenberg, Nancy; Bazely, Dawn; Mouland, G.
Open Access
Evaluating the Success of Deciduous Forest Restoration in Southwestern Ontario, Canada
(Heritage Resources Centre, University of Waterloo, 2000) McLachlan, S.M.; Bazely, Dawn
Forest fragmentation has resulted in reduced richness of native species in northeastern North America. Despite recent large-scale increases in forest cover, studies indicated that understorey herbaceous plant communities may take decades to recover. In 1994 and 1995, we assessed the effectiveness of restoration by comparing the understorey plant composition of 28 former cottage and road sites with less disturbed reference sites at Point Pelee National Park, Ontario, Canada. Sites were restored over a 35-year period. We took into account the effects of selected environmental and landscape variables. There was a significant increase in similarity between restored and reference sites as time-since-restoration (TSR) increased. Overall, there were no signifcant differences in the diversity of native species between restored and relatively undisturbed reference sites suggesting recovery of restored sites may have been unsucessful. However, there was still significant among-site variation in the composition of the native species component of these plant communities. When only restored sites were examined, variation in native species composition was associated with time since restoration, soil moisture, canopy cover, and distance to continuous forest. Native species were assigned vulnerability rankings according to their relative occurence in reference and restored sites. Spring-flowering herbs such as Hepatica acutiloba, Dicentra cucullaria, and Allium tricoccum, with ant or gravity dispersed seeds, were absent from restored sites and were defined as highly vulnerable. In contrast, summer and fall-flowering herbs, with verterbrate and wind-dispersed seeds, dominated restored sites and were assigned lower vulnerability rankings. Species assigned low and intermediate vulnerability rankings had colonized restored sites successfully. These intermediately ranked species should function as indicators of recovery. In contrast, species with high vulnerability rankings had not recovered at all and, because of their limited disperal ranges, may only recolonize restored sites if they are actively reintroduced.
Open Access
Recovery of Red Cedar Savanna and Oak Savanna Plant Communities: Report to Pinery Provincial Park & Point Pelee National Park for the 1999 Field Season
(Biology Department, York University, 2001-06) Tagliavia, Cecilia; Koh, Saewan; Bazely, Dawn
Executive Summary: 1. Southwestern Ontario is the most densely populated, urbanized, industrialized and intensively farmed part of Canada. The remaining natural habitat cover is 5-10%, and much of this has been subjected to intense human-induced disturbance in the past Conservation and habitat restoration is, to put it mildly, a huge challenge. 2. This report explains the 1999 fieldwork results of two projects, part of which comprises the research of Cecilia Tagliavia a York University M.Sc. student. The work done at Point Pelee by Ms. Tagliavia, followed up on the M.Sc. research of Nancy Falkenberg. 3. The overall aim of the research was to determine how best to restore Carolinian plant communities, specifically Oak Savanna and Red Cedar Savanna. 4. Both communities are to some degree a fire-dependent. Rare and endangered species (e.g. Wild Lupine and Karner Blue Butterfly) are present and oak savanna itself is considered to be extremely rare in Ontario and globally imperiled. 5. For Oak Savanna communities at Pinery Provincial Park, our goal was to assess the effects of restoration efforts (deer herd reductions and deer exclusion) on plant community composition. 6. Intensive deer herd reductions, and removal of planted pines at Pinery Provincial Park are allowing the Oak Savanna plant communities to move away from the species composition of the early to mid-1990s, towards communities characterized by prairie and savanna species. We support the proposals to continue deer herd reductions and to carry out prescribed burns at Pinery for the foreseeable future. 7. In the future, the recovery rates of these Oak Savanna communities will depend on the presence of a suitable seedbank and the dispersal rates of individual plant species from local seed sources. 8. For Red Cedar Savanna communities at Point Pelee National Park our goal was to assess the effects of restoration efforts (prescribed burns in 1997 and 1999, soil disking and manipulation of red cedar tree densities) on plant community composition. 9. At Point Pelee, there was a significant increase from 1997 to 1999 in the cover of species native to Red Cedar Savanna at one of the two experimental plots (De Laurier), while at the Nature Reserve the cover of native species declined, but this was not significant compared with 1997. Overall, the communities changed in opposite directions at the two experimental sites, most likely because the native seedbank and availability of seed sources varied. 10. We recommend that prescribed burns in Red Cedar Savanna sites be maintained and that desired species be actively reintroduced if no or low levels of local seed sources are available, in order for these species to compete more effectively with non-native species present at these sites.
Open Access
Report to the Endangered Species Recovery Fund, World Wildlife Fund, Toronto, Ontario, Canada on the 2000 field season.
(Biology Department, York University, 2001-07) Hynes, Kim E.; Tagliavia, Cecilia; Bazely, Dawn
1. Southwestern Ontario is the most densely populated, urbanized, industrialized and intensively farmed part of Canada. The remaining natural habitat cover is 5-10%, and much of this has been subjected to intense human-induced disturbance in the past. Conservation and habitat restoration is, to put it mildly, a huge challenge. 2. This report explains the 2000 fieldwork results of 3 projects funded by the ESRF, which comprise the research of 2 York University graduate students, Cecilia Tagliavia and Kim Hynes. 3. The overall aim of the research was to determine how best to restore Carolinian plant communities, specifically Oak Savanna and closed canopy Carolinian forest. 4. Oak savanna is to some degree a fire-dependent plant community. Rare and endangered species (e.g. Wild Lupine and Karner Blue Butterfly) are present and the community itself is considered to be extremely rare in Ontario and globally imperiled. 5. Overall, the 2000 field season has demonstrated that active management efforts in Carolinian plant communities have the potential of successfully restoring and rehabilitating highly disturbed habitats.
Open Access
Characteristics of expanding and stable populations of garlic mustard in Carolinian parks
(Heritage Resources Centre, University of Waterloo, 2002) Firanski, J. Carrie; Falkenberg, Nancy; Koh, Saewan; Bazely, Dawn
Garlic Mustard (Alliaria petiolata) is a short-lived monocarpic perennial introduced to North America in 1868 which reached Canada in 1879. It was first introduced to Point Pelee National Park in 1969 and Rondeau Provincial Park in the 1980s. Both parks have long histories of human-induced disturbance, with most recently high deer grazing pressure. We show that garlic mustard has become (Point Pelee NP) and is becoming (Rondeau PP) a predominant understorey herb from 1994 to the present, and that the two parks are in different phases of colonization. Our research suggests that the garlic mustard population at Point Pelee has stabilized while the Rondeau population is continuing to expand. We found a significant negative relationship between species diveristy and garlic mustard density for both of the parks. However, it is unknown whether garlic mustard is supressing native herbaceous species diversity, or whether low diversity is an outcome of the intense long-term grazing pressure exerted by deer on the native species. Interestingly, the garlic mustard populations at both parks have alternate years of high and low flowering densities, driven by intraspecific density effects. This may expalin the lack of negative association in garlic mustard density and native diversity in some years. Further research will include experiments with native species transplants into garlic mustard dominated sites to determine competitive interactions, and analysis of changes in distribution throughout the transects to determine rate of spread of expanding garlic mustard populations at Rondeau.
Open Access
Multiple Scale Effects of Overgrazing by White-tailed Deer (Odocoileus virginianus) in Eastern Deciduous (Carolinian) Forests
(Heritage Resources Centre, University of Waterloo, 2002) Koh, Saewan; Bazely, Dawn
Large herbivores such as white-tailed deer can have a significant impact on vegetation across multiple biological scales. We examined the relationship between plant community dynamics in several southern Ontario forest sites and ecosystem responses such as productivity, nitrogen dynamics, species diversity and ecosystem structure. Between 1992 and 1998, sites with a history of high deer densities (>50/km2) were compared with deer exclosures and long-term ungrazed sites. Ordination analyses showed older exclosures were similar to ungrazed sites, with higher woody stem densities and dominated by plant functional types relatively high in nitrogen. Both differed from grazed sites, with lower stem densities and dominated by functional types lower in nitrogen. Reductions in deer did not result in the recovery of overgrazed sites because deer mediated changes at the ecosystem level and depletions of desirable native species from seedbanks were the major determinants of successful trajectories. These results present implications for plant species conservation and re-establishment.
Open Access
A study of prescribed burns, tree and shrub layer in oak savanna plant communities in Southern Ontario: Pinery Provincial Park, Rondeau Provincial Park and Point Pelee National Park
(Heritage Resources Centre, University of Waterloo, 2002) Tagliavia, Cecilia; Bazely, Dawn; Koh, Saewan
Oak savanna is a rare plant community in Ontario, which has been intensely overgrazed by white-tailed deer in the study areas. The goals of the study were to: 1) assess vegetation recovery after deer herd reduction and prescribed burns at Pinery Provincial Park, 2) monitor savanna remnants at Rondeau Provincial Park and Point Pelee National Park. In the Pinery sites deer exclosures were built in 1994 in order to test for deer grazing. Following burning some of the sites at Pinery and at Rondeau has shown an increase in species such as Big Bluestem (Andropogon gerardii). In the unburned site at Rondeau native savanna species are present. In Pelee the Oak savanna remnants appear to be in an advanced stage of succession with closer canopy and forest type species. The tree and shrub density are similar, except for the tree density in the Point Pelee sand dune.
Open Access
Panel Commentary: An Approach for Monitoring in Ontario’s Provincial Parks and Protected Areas
(Heritage Resources Centre, University of Waterloo, 2002) Bazely, Dawn
Open Access
Shedding Light on the Problem of Deer Overgrazing in Carolinian Forests
(Centre for Wildlife and Conservation Biology, Acadia University, 2002) Hynes, Kim E.; Koh, Saewan; McLachlan, S.M.; Timciska, M.; Bazely, Dawn
In nearly a decade of research we have carried out a multi-faceted study of the impact of deer grazing in three major Carolinian parks: Point Pelee National Park, and Rondeau and Pinery Provincial Parks. This research has had a direct impact on management policy. We will review key findings of the research program and highlight what we consider to be our most general research finding, namely that the state of the overhead canopy in Carolinian forests appears to have a major impact on the composition of understorey plant communities. We suggest that deer overgrazing has initiated a process that has signiticantly altered understorey light conditions. Our hypothesis is that increased canopy gaps, initially caused by deer preventing forest regeneration, have led to trees being more susceptible to wind throw. This further opens the canopy, leading to increased light levels in the understorey, which in turn drive changes in the vegetation. Non-native, invasive species can take advantage of the increased light conditions and appear to replace and suppress native woodland species, which are adapted to shade. The forest may then switch to some alternative stable state. Currently, analysis of long-term data sets is aimed at evaluating this hypothesis. Our current research aims to quantify the relationship between understorey light levels and the plant community, and it will establish whether there is some threshold light level beyond which many vulnerable native understorey species cannot survive, and are suppressed by exotics. In this respect it is of general interest to anyone working in a degraded, highly disturbed forest, with an interest in habitat restoration.
Open Access
Restoring highly fragmented populations of herbaceous spring ephemerals in a severely grazed Carolinian forest
(Heritage Resources Centre, University of Waterloo, 2003) Firanski, J. Carrie; Bazely, Dawn
High deer populations at a number of provincial parks (e.g., Rondeau and Presqu'ile Provincial Parks) throughout Ontario are seen to pose a threat to the natural state of the park. The effects of grazing by white-tailed deer (Odocoileus virginianus), on the structure of a forest canopy were investigated at Rondeau Provincial Park in southwestern Ontario in response to the lack of investigation into landscape level change incurred by these high populations. Canopy gap data was compiled from analysis of three sets of air photos (1955, 1972 and 1978) for the park. Overall, average area and frequency of gaps increased over the 23 year period.
Open Access
What is Ecosystem Recovery and How Should we Measure it in Our Parks?
(Heritage Resources Centre, University of Waterloo, 2004) Bazely, Dawn; Koh, Saewan; Firanski, J. Carrie; Tagliavia, Cecilia
Southwestern Ontario, or the Carolinian ecozone, is the most heavily populated region of Canada. Natural habitat cover is as low as 5% in some counties. Furthermore, human-induced disturbance has been great in many of the remaining natural habitats, including Rondeau and Pinery Provincial Parks and Point Pelee National Park. Consequently, managers have recognized the need for active habitat restoration. How do managers know that their restoration efforts have lead to ecosystem recovery and that conservation targets are being met? This question presupposes that ecosystem response to management can be easily quantified. Lessons learned from 12 years of research into forest and savanna responses to management for high white-tailed deer populations and prescribed burning in these parks will be used to address this question. Our three main conclusions are: 1) "one size does not fit all" when it comes to assessing different management regimes, 2) " a multi-scale approach is essential" - without one, important habitat changes will likely be missed; and, 3) "change is slow" - these habitats usually respond over decades.
Open Access
Invasive Plants of Canadian Woodlands – Scientific Challenges
(Heritage Resources Centre, University of Waterloo, 2004) Bazely, Dawn; Firanski, J. Carrie; Koh, Saewan
About 28% of the Canadian flora are non-indigenous species (NIS). What is their impact on woodlands? While some spectacular introduced invasive plants in North America function as keystone species, altering ecosystem structure and function, most NIS simply increase the species richness of an area. We have found that some so-called invasive plant species are likely not having a major impact on plant communities, and that ecosystem and landscape-level disturbances are of much greater significance in determining plant community composition. Predicting which introduced species may become a problem remains a challenge, although, in keeping with the literature, we have found that one problem species, Japanese Barberry, was deliberately introduced as a garden plant and then escaped. Additionally, we also found that human-induced disturbance is associated with the spread of non-native plants.
Open Access
A bee diversity survey in oak savannah habitats in Rondeau Provincial Park, Ontario
(Heritage Resources Centre, University of Waterloo, 2004) Mac, Lily; Bazely, Dawn
A survey of bee diversity was conducted in two oak savannah habitats - Oak Savannah 3 (03) and South Point (SP) - in Rondeau Provincial Park in Southern Ontario, Canada. The bee community composition of 03 and SP were similar in both sites according to a Detrended Correspondence Analysis (DCA) and Sorensen's coefficient of community similarity. However, bees appeared to prefer the SP habitat over 03 as determined by the greater bee species abundance, richness, Shannon diversity, and evenness values found in SP. This is possibly due to the larger habitat area and greater plant species richness and abundance of SP compared to 03. The decline in bee species richness and abundance toward the end of the summer correlated with the decline in plant richness and abundance because bees rely on the nectar and pollen in plants that are flowering as sources of food.