Humber River State of the Watershed Report - Terrestrial System

2008 Humber River State of the Watershed Report – Terrestrial System

EXECUTIVE SUMMARY

• Historically the Humber Watershed land base was approximately 90% forest cover. The forests of pre-settlement Ontario were also interspersed with wetlands, mainly marshes and swamps and to a lesser extent, native meadow habitats.

• In a human dominated landscape such as the Humber River watershed, a terrestrial natural heritage system for a defined area consists of the lands that have the greatest existing or potential value of supporting a biologically diverse network designed to protect and restore natural features and ecological functions across that area's overall landscape. Without these processes, ecological integrity and biodiversity decline.

• The methods used to evaluate the state of terrestrial biodiversity in the Humber River watershed takes into account multiple scales: the landscape scale (remote sensing and modelling); and vegetation communities and species scale (field inventories). These results, along with historical data, can then be used to set meaningful targets for terrestrial biodiversity protection and restoration in the watershed.

• The habitat patches in the study area were assessed using the TRCA’s Landscape Analysis Model. This model assesses the landscape level patch quality by assigning scores to each natural habitat patch for its size (area), shape (perimeter-to-area ratio) and the matrix influence (influence of the surrounding land use).

• Due to the small size of many of the remnant patches, their linear shape, and the highly urbanized matrix of land uses surrounding them, most patches of natural cover in the watershed are in the mid-functioning or ‘fair’ range in terms of quality. The fair range of patch quality is where avian species of concern begin to be lost from the natural system. Currently, the Humber River watershed is at a state of impending crisis from a patch quality standpoint. As the matrix becomes more and more urban, or as patch size or total quantity of natural cover is reduced, it can be expected that patches will cease to support these sensitive species. Quality of habitat patches is better in the northern portion of the watershed where natural cover patches tend to be larger and less influenced by urban land uses. Almost all of the higher quality habitat patches lie within the Main and East Humber subwatersheds. In the southern and middle portions of the watershed, where urban land uses and agricultural uses are more prevalent, the natural system is highly fragmented and there is a considerable lack of tableland forest.

• Connectivity within the Humber River watershed is almost entirely north-south with very little continuous cover running east-west that connects areas of tableland forest. Most of the connectivity is through narrow riparian corridors. Well-connected corridors are for the most part limited to the Oak Ridges Moraine area.

• The Humber Watershed currently contains 32% natural cover. Much of this cover is meadow type habitat with approximately 18 % of the watershed containing forest cover. Although this amount of natural cover is greater then some of the adjacent watersheds (e.g., Don and Highland) it is still well below the quantity target of 39% natural cover set using the TRCA's Terrestrial Natural Heritage System Strategy methodology.

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• Only 1.6% of the watershed's total area includes wetlands such as marshes, thicket swamps, bogs and shallow ponds. Historically, wetlands in this region would have covered anywhere between 11% and 16% of the landscape.

• There were 50 indicator species that were selected as being representative of a range of habitat types. These were used to roughly illustrate the degree of ecological function that the various subwatersheds provide. The Main Humber subwatershed, with the extensive habitats in the north, contains 49 of the 50 indicator species. The highly urbanized Black Creek subwatershed was found to contain only 25 of the 50 indicator species.

• The overwhelming management consideration in order to maintain and improve the function of the terrestrial natural heritage system is to implement the TRCA Terrestrial Natural Heritage System Strategy. This will result in increased natural cover by restoring habitats in strategic locations to build upon existing natural areas. This will help to improve the quality of the habitat patches by increasing their average size, improving their shape and increasing connectivity throughout the landscape. A more robust natural system will also help guard against the negative matrix influences associated with increased urban land use that is anticipated in the future

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TABLE OF CONTENTS

1.0 INTRODUCTION...... 1 2.0 UNDERSTANDING THE TERRESTRIAL SYSTEM IN THE HUMBER ...... 2 3.0 MEASURING AND EVALUATING THE TERRESTRIAL SYSTEM...... 4 3.1 Data Collection - Measuring the System...... 4 3.2 Evaluating the Terrestrial System...... 6 4.0 EXISTING CONDITIONS IN THE HUMBER RIVER WATERSHED...... 8 4.1 Landscape Level Context - Results of Remote Sensing and Modelling ...... 8 4.2 Vegetation Community and Species Levels - Results of Field Inventories ...... 20 4.3 Biological Threats ...... 26 5.0 SUMMARY AND MANAGEMENT CONSIDERATIONS ...... 28 6.0 REFERENCES...... 30

LIST OF APPENDICES

APPENDIX A INDICATOR SPECIES FOR HUMBER RIVER SUBWATERSHEDS...... 31 APPENDIX B TERRESTRIAL SCORING SYSTEM FOR HABITAT QUALITY ...... 33

LIST OF FIGURES

Figure 1 Natural, Urban and Agricultural Cover in the Humber River Watershed, 2002...... 3 Figure 2 Target Terrestrial Natural Heritage System, Humber River Watershed...... 5 Figure 3 Landscape Analysis of Terrestrial System - Existing Conditions (2002) ...... 9 Figure 4 Quality Disribution within the Humber Watershed (Existing)...... 11 Figure 5 ELC Sites with a Ranking of Severly Disturbed for Trampling, Trash, and Exotics (1999-2005 Data) ...... 16 Figure 6 Physiographic Regions...... 22

LIST OF TABLES

Table 1 Watershed Report Card Rating - Quality Distribution of Natural Cover ...... 14 Table 2 Compatibility of Use of Natural Areas (1999-2005 Evaluated Areas)...... 15 Table 3 General Land Use/Land Cover Statistics – Humber River Watershed, 2002 ...... 17 Table 4 Natural Land Cover Statistics – Humber River Watershed, 2002 ...... 17 Table 5 Terrestrial Natural Heritage System (TNHS) Target for the Humber River Watershed ...... 18 Table 6 Watershed Report Card Rating - Quantity of Natural Cover...... 20 Table 7 Observations of Indicator Species in Humber River Subwatersheds ...... 26

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1.0 INTRODUCTION

In 1997, the Humber Watershed Task Force released the Humber River Watershed Strategy, Legacy: A Strategy For A Healthy Humber (MTRCA, 1997), which provided thirty objectives for a healthy, sustainable watershed, and a set of actions necessary to achieve them. It also provided an overview of the state of the Humber River watershed at that time. Since the release of the watershed strategy, a significant amount of new information has become available through monitoring, special studies and the experiences of watershed partners.

In 2004, the Toronto and Region Conservation Authority (TRCA), in partnership with watershed municipalities and the Humber Watershed Alliance initiated a study to develop an integrated watershed management plan for the Humber River. This study was initiated to fulfill the watershed planning requirements of the Oak Ridges Moraine Conservation Plan , 2002, and to update the strategies and recommendations of Legacy, in light of new information, a stronger scientific foundation and better understanding of the effects of human actions on natural ecosystems. The watershed plan is intended to inform and guide municipalities, provincial and federal governments, TRCA, non-governmental organizations and private landowners regarding management actions needed to maintain and improve watershed health.

This State of the Watershed Report provides updated information on current conditions, emerging trends and identifies key watershed management issues and opportunities in the Humber pertaining to the terrestrial system. Indicators of watershed health and associated targets are used to rate current conditions. Ratings for a full suite of indicators of watershed health are summarized in, Listen to Your River: A Report Card on the Health of the Humber River Watershed (TRCA, 2007b).

This State of the Watershed report also provides an overview of current management strategies and introduces some innovative approaches to address key issues, which will be considered for inclusion in the Humber River Watershed Plan . It begins with an overview of factors that influence watershed conditions and the indicators being used to track current conditions and evaluate watershed health.

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2.0 UNDERSTANDING THE TERRESTRIAL SYSTEM IN THE HUMBER

For several millennia after the last ice age the terrestrial system in the Humber River watershed was dominated by forest. Vast tracts of deciduous, coniferous and mixed forest were interspersed by wetland and native meadow (areas maintained as open habitat do to natural disturbance). Natural cover blanketed the entire watershed. Over a century ago, land conversion to accommodate small settlements and agricultural land uses fragmented this once contiguous terrestrial cover into remnant and often isolated habitat fragments. Vast forests were clear-cut and countless hectares of wetland were drained throughout the watershed. Lost were many species adapted to the extensive natural habitats of the watershed, including eastern cougar, black bear, and elk. Some species were immediately excluded by direct habitat removal while others gradually died out over time because of unsuitable conditions. In some instances populations were drastically reduced or extirpated from the watershed - such as those of large mammals - because they were viewed as nuisances or as threats to the early settlers.

The remnant forest and wetland patches in the watershed were drastically reduced in size as settlement and land clearing progressed. The quantity, quality and distribution of the terrestrial system were altered drastically. This created conditions in the landscape which were intolerable to a number of species. For example, habitat patches were often isolated from each other, separated by extensive agricultural fields. Linkages and safe passageways were not maintained in the landscape to allow for the successful movement and dispersal of species. In addition, important natural processes such as disturbance dynamics, nutrient cycles, vegetation community succession, pollination, and species dispersal were greatly compromised in this fragmented landscape. These processes can only be maintained if there is substantial natural cover, well distributed and connected across the watershed. In absence of these processes, ecological integrity and biodiversity in the watershed are put at risk

Over the last fifty years, many of the agricultural fields and small settlement areas in the watershed have been replaced by higher density urban development. These changes have introduced a different threat to the watershed’s terrestrial biodiversity. Compared with a rural or agricultural surrounding or “matrix”, an urban matrix is considerably more intrusive to small remnant habitat patches and species due to increased pollution, refuse dumping, recreational pressures, invasive alien species, and predation by roving pets. Furthermore, urban land uses do not provide for the same degree of connectivity function that rural areas do. Figure 1 shows the existing terrestrial natural heritage system in the Humber watershed.

As urbanization continues to move northward throughout the watershed, the quantity, quality and distribution of the terrestrial system, and its ability to support species and ecological processes continues to be compromised.

Humber_Terrestrial_System_FINAL_112907F.doc 2 Figure 1 Natural, Urban and Agricultural Cover in the Humber River Watershed, 2002 Humber River State of the Watershed Report – Terrestrial System

3.0 MEASURING AND EVALUATING THE TERRESTRIAL SYSTEM

To maintain or improve ecological conditions in the watershed, a more robust terrestrial natural heritage system is needed. Recognizing the need to protect the broader system rather than just significant areas to maintain healthy ecosystems, TRCA initiated the formulation of a Terrestrial Natural Heritage System (TNHS) Strategy (TRCA, 2007c) for lands within its jurisdiction. The TNHS Strategy seeks to protect, restore and expand a targeted land base to provide for a robust terrestrial natural heritage system in the TRCA’s watersheds

TRCA’s regional target system was refined for the Humber watershed to ensure that our objectives for quantity, quality and distribution of terrestrial cover could be met. This target system for the Humber represents the minimum land base that should be secured, protected and restored to a natural state over the next century. Figure 2 Illustrates the TRCA’s draft Target Terrestrial System for the Humber River watershed.

The methods used to inventory and evaluate the state of terrestrial biodiversity in the Humber River watershed are briefly described here. This approach takes into account multiple scales, from the entire watershed down to the individual site level.

3.1 Data Collection - Measuring the System

At the watershed scale, terrestrial system data was collected via remote-sensing through the interpretation of digital aerial photography. Terrestrial habitats and land use types were identified and digitized from 2002 digital color aerial photography and the information is stored in the TRCA’s Geographic Information System. The terrestrial habitat classes identified through remote sensing include forest, wetland, cultural meadow and coastal habitats (beaches and bluffs). An advantage to remote-sensed data collection is that the entire watershed can be characterized in a relatively short period of time and updates can be routinely made as new aerial photography becomes available. In this way, changes in land use cover can be easily tracked over an extended time frame. However, remote-sensed data does not capture detailed information regarding species composition, community structure, local disturbances, and etcetera.

Detailed Information on vegetation communities and species in the watershed was collected in the field to compliment the remotely sensed data. The TRCA felt it was necessary to inventory at least 40% of the Humber’s terrestrial system prior to undertaking the watershed planning study . Field inventories took place during the appropriate season by TRCA and OMNR biologists and volunteer observers over the last several years. Vegetation communities were mapped according to the Ecological Land Classification (ELC) System of the Ontario Ministry of Natural Resources (Lee et al., 1998). Detailed checklists for flora and fauna species are created for each site inventoried. In addition, TRCA’s species of concern (L1 - L3 species, and L4 species within urbanized areas) were mapped as point data using the data collection protocol developed by TRCA (TRCA, 2005a). All data is digitized and incorporated into TRCA's Geographical Information System (GIS).

Humber_Terrestrial_System_FINAL_112907F.doc 4 Figure 2 Target Terrestrial Natural Heritage System, Humber River Watershed Humber River State of the Watershed Report – Terrestrial System

3.2 Evaluating the Terrestrial System

The Humber watershed was evaluated at two scales. The landscape level context and the vegetation communities and species level. At the landscape scale predictive models based on field collected species and community data and quantitative assessment of habitat were used. Species and community level data was also used to establish trends in distribution, occurrence and abundance as well as degree of disturbance/human impact

Landscape Level Context

There are two main parameters used to measure, evaluate and set objectives or targets for the Terrestrial System at the landscape scale. These parameters were developed looking at both species and vegetation community data and its abundance and distribution across the landscape. This then fed into the development of the ArcView GIS based computer model used here. In place of species and vegetation community data across the jurisdiction these landscape parameters/model can in many cases act as a surrogate for this information. The landscape parameters used here are the quality distribution and quantity of natural cover, and are discussed below.

Quality Distribution of Natural Cover

At the landscape level of detail, the habitat patches in the study area were assessed using the Landscape Analysis Model (LAM), developed by TRCA using ArcView GIS. This model assesses the landscape-level patch quality by assigning scores to each natural habitat patch for its size (area), shape (perimeter-to-area ratio) and the matrix influence (influence of the surrounding land use). The results (patch scores) for size, shape and matrix influence can be used individually or the scores for each of the three measures can be combined together to obtain a total patch score for each patch in the study area. It is the total (combined) patch scores that are used in this report to evaluate the quality of habitat patches for existing conditions; however in some instances the individual measures are also highlighted. Appendix B provides a summary of the scoring system. For further detail on the landscape level analyses, refer to TRCA’ s Evaluating and Designing Terrestrial Natural Heritage Systems (TRCA, 2007a).

Quality is not just viewed on its own across the watershed, distribution of this quality is considered at the same time. If the distribution of quality of habitat is poor, then the distribution of species of concern will also be poor. Where these species occur there is often a high correlation to the range and quality of ecosystem services provided. Therefore, for a watershed to deliver the range of ecosystem services equally across the watershed and provide the habitat necessary to maintain a complex and dynamic terrestrial system, good quality habitat must be distributed evenly. By examining the quality of habitat across each subunit or subwatershed the distribution of quality of habitat, or “quality distribution” can be ascertained.

Aside from the three measures used in the LAM, terrestrial system connectivity and forest interior were also used to assess the quality of the terrestrial system for the Humber River watershed. Connectivity, which is important for the dispersal and mobility of many flora and fauna species in a fragmented landscape, is assessed qualitatively through visual interpretation

Humber_Terrestrial_System_FINAL_112907F.doc 6 Humber River State of the Watershed Report – Terrestrial System of natural cover maps. The degree of habitat connectivity is examined within the watershed and between neighboring watersheds. In addition to a well-connected system, many species of flora and fauna are dependent on forest patches that have extensive forest interior conditions. Forest interior calculations are used to assess the degree of interior forest habitat, (i.e., the amount of forest habitat that is greater than 100 metres from the edge of the forest patch) using 100 metre increments. A recognized distance for deep interior conditions occurs at 400 metres from the patches edge.

Quantity of Natural Cover

Once aerial photographs are interpreted, digitized and incorporated into the GIS, the amount of natural cover can be easily quantified at any scale. Quantity is highly correlated to the quality distribution of natural cover (i.e., with additional quantity of natural cover placed strategically, targets for quality distribution can be met).

Vegetation Communities and Species Level Contexts

The vegetation community and species data collected in the field are extremely valuable when assessing the state of the watershed’s terrestrial system or of an individual habitat patch. Not only does this information inform and update the landscape level analysis models used to assess quality distribution, but the species and community type representation, abundance and distribution from selected sites in the landscape are excellent indicators of how the terrestrial system is functioning and responding to the surrounding land use practices. Where available, vegetation community and species information from historical records (e.g., records older than 25 years) were used to compare the findings of recently surveyed areas and relate species responses to the changing matrix over time. Information about the behaviour and ecology of species present or in some cases no longer present, in the watershed was also used to make inferences and speculate about the state of the terrestrial system. Both native and invasive alien species are considered

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4.0 EXISTING CONDITIONS IN THE HUMBER RIVER WATERSHED

The following sections provide an assessment of the current condition of the terrestrial system in the Humber River watershed, based on the results of remote-sensing of the entire watershed’s natural system and field inventories across the watershed (TRCA, 2003a). Presented, are the results of data collection for the recent years up to November 2004 (landscape, 2002; vegetation communities, 1980 to 2004; flora species 1998-2004; fauna species 1996 to 2004).

4.1 Landscape Level Context - Results of Remote Sensing and Modelling

The Humber River watershed today is dominated by human land uses. The total area of the Humber River watershed, based on 2002 aerial photography interpretation, can be divided into: 32.2% natural cover (forest, successional, wetland, meadow and beach/bluff), 0.6% open water, 26.1% urban land use and 40.2% agricultural and/or rural land uses. The results of the natural cover analysis are discussed below.

Quality Distribution of Natural Cover

The results of the Landscape Analysis (total patch scores) for the Humber River watershed are shown in Figure 3. This figure provides a good overall impression of the quality of the habitats remaining in the watershed.

Due to the small size of many of the remnant patches, their linear shape, and the highly urbanized matrix, most patches are within the mid-functioning or “fair” range in terms of quality (L3 ranking, orange-colored patches, score a 9 or 10 out of a possible 15 points). Avian species of regional concern have been shown to be present in habitat patches that generally range from the mid- to high-level (fair to excellent range) of quality (Kilgour, 2003) (patches color-coded as orange, light green and dark green in Landscape Analysis Figure 2). The “fair” range of patch quality is where avian species of concern begin to be lost from the natural system. Overall, the measures for quality add up to a ‘C’ grade for the Humber watershed. This grade is based on the zonal mean (i.e., area weighted mean) for total habitat patch scores (based on combined individual scores for size, shape and matrix influence) using the following breakdown: Very Poor = E grade, Poor = D, Fair = C, Good = B and Excellent = A. See Appendix B for more detail on scoring and grading of habitat patch scores.

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When we begin to consider the distribution of this quality a more alarming picture of the state of the watershed’s terrestrial system begins to emerge. Almost all of the higher quality habitat patches (ranked L1 and L2) are within the Main and East Humber subwatersheds (Figure 4). Within these subwatersheds some high quality habitat patches (patches ranked L2) remain, yet they are generally in a form or shape that leaves them vulnerable to external negative influences or they are not well connected to the remainder of the system. Unless the system is enhanced, these areas of higher quality will likely decline in quality over time and cease to support the current suite of species. The fully urbanized Black Creek and Lower Humber subwatersheds are in stark contrast to the Main and East Humber subwatersheds. Habitat patches in Black Creek and Lower Humber subwatersheds are predominantly poor quality; characterized by small fragmented patches of a generally poor and often linear shape. Habitat in these subwatersheds is often limited to riparian corridors with very little tableland forest.

Whether good quality habitat is more heavily distributed to the north (as in the case in the Humber River watershed) or to the south of a watershed (as is the case in the adjacent Rouge River watershed), such an unbalanced quality distribution can have profound effects on the regional natural system. For example, it can effect how safely migrant birds are able to pass through the watershed, the accessibility of essential habitat to resident species, and the degree of flood attenuation in the watershed. The fragmentation of good habitat also affects the movement of less mobile fauna species and most certainly flora, a fact that becomes significant in terms of promoting genetically viable and variable populations and the restocking of habitats that have undergone a localized disturbance or recent restoration.

According to this analysis, the Humber River watershed receives a ‘fair’ watershed report card grade from a patch quality standpoint (Table 1). This means that while it supports many species of concern it is within a quality range where many species and communities are on the cusp of disappearing. Even if land uses remained unchanged in the watershed, a decline in native biodiversity over time would likely continue as many species are slow to react (e.g., vegetation community shifts, invasive species spread) and there can be a lag time of several years to decades before the effects of urbanization and public use are seen on the distribution of some flora and fauna species. As such a static urban growth scenario is highly unlikely, and population growth and development continues within the watershed we will see many of these species and communities pushed over this cusp into non-existence. The existing terrestrial system, although receiving a ‘fair’ grade and currently supporting many sensitive species and communities, needs restoration and enhancement work if, at a minimum, we are to stem the loss of species and vegetation communities of concern within the watershed, let alone recover those species and communities we have already lost.

As the matrix continues to urbanize, and/or as patch size or total natural cover is further reduced, it can be expected that patches will cease to carry out important functions and support sensitive species. Patches must be large enough to provide ample interior habitat conditions and mitigate the negative effects of the urban matrix, and be well-connected or in close proximity to other natural patches, to ensure population viability.

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Figure 4 Quality Disribution within the Humber Watershed (Existing)

18000

16000

14000

12000

L5 10000 L4 L3 L2

Hectares 8000 L1

6000

4000

2000

0 Lower Black West Main East Humber Creek Humber Humber Humber Subwatershed

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Habitat Patch Size and Shape Edge Effect Within the Humber River watershed, habitat External influences (either patches are of a range of size classes, but are environmental or anthropogenic) that have a negative impact on a habitat on average of a ‘fair’ size. The mean average patch, such as wind, exotic species, score for patches is a 3 out of a possible 5 predators, parasites, etc. (Table 1). Larger patches are mainly located in the east and northern portions of the main subwatersheds but in the more southern portions of the watershed the patches are considerably smaller. Overall, patches are ranked between good and excellent based on the measure for habitat patch size. In general, in order to receive this rank forest patches on average are larger then 10 hectares and wetlands are greater than 3 hectares. This is why area sensitive species such as least bittern, scarlet tanager and broad-winged hawk are present in the watershed. The largest contiguous forest patch in the Humber River watershed is 490 hectares in size, and is located in the northwest corner of the watershed at the corner of Airport Road and Finnerty Sideroad. However, this forest block has a poor shape, as do most larger forest patches in the watershed, exposing it to increased edge effects. The majority of habitat patches in the Humber fall into the ‘poor’ category for shape. The mean average score for patches is a 2 out of a possible 5 (Table 1) as many of the patches remaining are linear and follow the valley corridors.

Matrix Influence

Surrounding each habitat patch is a matrix of land use types that are generally categorized as either urban, agricultural or natural. Matrix influence is a measure of the relative degree to which land uses in the vicinity of the habitat patch are likely influencing (positively or negatively) the quality of habitat the patch is capable of supporting. Urban land uses are assumed to exert a high negative influence on the quality of nearby habitat patches, while agricultural land uses are assumed to exert a moderate to low negative influence. When other types of natural land cover are nearby, this is assumed to exert a positive influence on the quality of the habitat that the patch is capable of supporting.

On average, matrix influence scores fall within the ‘good’ range. The mean average score for patches is a 4 out of a possible 5 (Table 1), reflecting the fact that much of the remaining natural cover is located in rural areas and is surrounded by predominantly agricultural land uses.

For the purpose of better reflecting the diversity of the TRCA watersheds, the TNHS Strategy divided the region into four distinct terrestrial natural heritage planning zones: the Urban, Urbanizing, Rural/Agricultural, and Oak Ridges Moraine - Niagara Escarpment Zones. Each zone has its own combination of characteristics (e.g., physiography, dominant land uses, and land use policies) that influence the management approaches needed to achieve the target terrestrial natural heritage system. Under present conditions, the Urban Zone in the Humber River watershed accounts for approximately 29% of the watershed’s area.

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The Urbanizing Zone - representing 16% of the watershed - consists mainly of agricultural lands that are within designated urban or settlement areas as defined by municipal official plans, and are currently being developed or are committed to development to accommodate the region's continuing rapid growth.

Assuming development trends remain unchanged, the rural zone will continue to decrease in area as the urban zone nears 45% of the total watershed area. Unless actions to improve habitat patch quality are undertaken and measures to mitigate negative influences of surrounding urban land uses are put in place, the added stress that further urbanization will put on the terrestrial system will result in further loss of biodiversity and ecological integrity and diminished quality of life for watershed residents. Recent provincial initiatives such as the Greenbelt Plan will hopefully help to curb some of the negative effects. For example, the Greenbelt Plan will benefit the watershed’s terrestrial system in the future by limiting the extent of urban development in the Humber River watershed, and by maintaining a more favourable agricultural matrix in the Greenbelt Plan area. However, the plan does not extend over what is currently all-of-the rural zone, and the targets of the Province’s Growth Plan for the Greater Golden Horseshoe for intensification in existing urban areas will only emphasize the need for a robust terrestrial system that can withstand these future urban stresses.

Terrestrial System Connectivity

Linkages or connectivity between patches within the watershed are almost entirely north-south with very little continuous cover running east-west that connects areas of tableland forest (Figure 1). This is due to the fact that the majority of the linkages within the landscape are through riparian corridors. Unfortunately, as with most riparian corridors, much of this continuity is achieved through rather narrow riparian habitat where there is little opportunity for species of conservation concern to persist. The lack of tableland forest, as previously noted, has effectively severed all upland connectivity within the cities of Toronto, Brampton, and southern portions of Vaughan and Caledon. Well-connected corridors are for the most part limited to the Oak Ridges Moraine area.

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Table 1 Watershed Report Card Rating - Quality Distribution of Natural Cover Objective: To protect, restore and enhance terrestrial natural heritage Overall system quality and function to minimize the negative influences of Rating surrounding land uses. C

Indicator Measure Target

Quality Total Patch Quality Scores The quality target is determined Distribution of - range of total scores based on the by the zonal mean total patch natural cover weighted scores for Size, Shape, and score of the targeted terrestrial Matrix Influence for all patches . system for the watershed

Total Score Total Score Humber watershed...... 9.8- fair Humber watershed...... 11.0- good

Subwatersheds Subwatersheds Black Creek...... 8-poor Black Creek...... 7.4- poor East Humber...... 9.9-fair East Humber...... 11.2- good Lower Humber ...... 7.7-poor Lower Humber ...... 8.6- poor Main Humber...... 10.3-fair Main Humber...... 11.8- good West Humber...... 8.8-poor West Humber...... 9.5- fair

Patch Size Scores -increase patch sizes by restoring (Size Score 3 - fair) land to natural cover as indicated - range of habitat patch size scores) by the watershed’s target based on interpretation of aerial photos terrestrial natural heritage system

Patch Shape Scores - enhance patch shape to be (Shape Score 2 -poor) more round with lower edge to - range of habitat patch shape scores area ratios as indicated by the based on interpretation of aerial photos watershed’s target terrestrial natural heritage system Matrix Influence Scores (Matrix Score 4 - good) - mitigate negative external - range (histogram of matrix influence influences of the matrix and target scores of all patches in the watershed. a ratio of urban/ rural/natural land The area considered as the matrix of a uses as indicated by the patch is a 2 km radius from its edge. watershed’s target terrestrial natural heritage system Disturbances in natural areas (Ratios range 118-1,035:14,547) - maintain or reduce the ratio of - ratio of the area of severely disturbed severely disturbed area to total ELC patches to the total area of ELC evaluated area patches for trampling/trails, trash/dumping, and exotics

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Disturbances in Natural Areas

During field data collection and mapping of ELC vegetation communities, the extent of disturbance to communities is assessed. Disturbance for each community is ranked from 1 (light) to 3 (severe) for each of a number of stresses, including trampling/trails, trash/dumping, and exotics. Figure 5 shows visited sites that were ranked as severely disturbed (1999-2005 data). Table 2 shows the extent of disturbance at evaluated sites. Exotics appear to be the most widespread and evenly distributed problem, with 7.1% of the area visited ranked as severly disturbed. There seem to be hot spots of trampling in Cold Creek and the West Branch of the West Humber River. Dumping appears to be less of an issue and is also fairly evenly distributed. Disturbances of these sorts and others (e.g., logging, grazing) affect the health of natural areas and the quality of nature-based recreational experiences, on those sites where recreation is permitted.

Table 2 Compatibility of Use of Natural Areas (1999-2005 Evaluated Areas) Disturbance Type Ratio of Severely Disturbed % of Evaluated Area that is Area to Total Area Evaluated Severely Disturbed Trampling/trails 241:14,547 1.9 Trash/dumping 118:14,547 0.8 Exotics 1,035:14,547 7.1

Quantity of Natural Cover

Tables 3 and 4 summarize the results from landscape scale analysis of land use and land cover, based on interpretation of 2002 aerial photography. In 2002, the Humber River watershed contained approximately 29,096 hectares of natural land cover (forest, wetland, successional, meadow, and beach/bluff habitats), representing 32.2% of the watershed area.

The objective for the quantity of natural cover in the Humber River watershed is to protect, restore and increase the amount of natural cover. The minimum target for natural cover in the Humber River watershed that has been established using the TRCA’s Terrestrial Natural Heritage Strategy methodology is 39% of the total watershed area. This means that restoration of natural cover on an additional 13770 hectares of land in the Humber River watershed is needed to create a healthy and functioning terrestrial system (Table 5). Figure 2 and Table 5 describe the draft Humber River watershed terrestrial natural heritage system target, which is based on the regional terrestrial natural heritage system, but refined at the watershed-scale based on available knowledge of opportunities and constraints.

Of the 32% natural cover, 18.3% of this is forest, including mixed forest, deciduous forest, coniferous forest, successional (regenerating) lands, treed swamps and plantations (Figure 1). Natural coniferous forest is relatively uncommon in the Great Lakes-St. Lawrence Mixed Forest Zone, although it does occur at some sites in the northern portions of the watershed. In addition to natural coniferous forest, are red and white pine forests that were planted on the Oak Ridges Moraine in the middle of the 20th century after inappropriate farming caused major erosion problems. These plantations have been found to serve as suitable habitat for many of the coniferous forest-dependent flora and fauna species in the TRCA jurisdiction.

Humber_Terrestrial_System_FINAL_112907F.doc 15 Figure 5 ELC Sites with a Ranking of Severly Disturbed for Trampling, Trash, and Exotics (1999-2005 Data)

Humber River State of the Watershed Report – Terrestrial System

Table 3 General Land Use/Land Cover Statistics – Humber River Watershed, 2002 General Land Subwatersheds Total Watershed Use/Land Cover Black Creek East Humber Lower Humber Main Humber West Humber Class hectares % of hectares % of hectares % of hectares % of hectares % of hectares % of total total total total total total area area area area area area Agriculture 26.86 < 1 9130.03 46 0.04 < 1 14569.03 41 12559.05 62 36285.01 40.2 Urban 5457.14 84 3362.12 17 6521.02 83 4304.9 12 3963.39 19 23608.56 26.2 Natural 802.13 12 7062.38 36 1210.63 15 16527.7 46 3492.99 17 29095.83 32.2 Open Water 1.14 < 1 190.32 1 89.25 1 185.71 1 95.47 <1 561.89 0.6 Vacant 171.01 3 133.2 < 1 2.00 < 1 92.08 <1 308.05 2 706.34 0.8 Total Area 6458.28 100 19878.06 100 7822.94 100 35677.42 100 20418.94 100 90255.63 100

Table 4 Natural Land Cover Statistics – Humber River Watershed, 2002 Natural Land Cover Subwatersheds Total Watershed Class Black Creek East Humber Lower Humber Main Humber West Humber hectares % of hectares % of hectares % of hectares % of hectares % of hectares % of total total total total total total area area area area area area Beach/Bluff 0 0 0 0 0 0 2.46 < 1 0 0 2.46 < 1 Forest 300.48 4.6 4095.4 20.6 599.31 7.7 10057.67 28.2 1471.16 7.2 16524.02 18.3 Meadow 476.12 7.4 2126.25 10.7 540.07 6.9 4762.31 13.3 1699.1 8.3 9603.84 10.6 Successional 13.8 < 1 349.34 1.8 57.23 < 1 925.01 2.6 218.32 1.1 1563.7 1.7 Wetland 11.73 < 1 491.39 2.5 14.03 < 1 780.24 2.2 104.41 0.5 1401.81 1.6 Total Area 802.13 12 7062.38 36 1210.63 15 16527.7 46 3492.99 17 29095.83 32.2

17 Humber River State of the Watershed Report – Terrestrial System

Table 5 Terrestrial Natural Heritage System (TNHS) Target for the Humber River Watershed Parameter Subwatersheds Total Watershed Black Creek East Humber Lower Humber Main Humber West Humber hectares % of hectares % of hectares % of hectares % of hectares % of hectares % of total total total total total total area area area area area area Existing Natural 437.38 7 5194.90 26 850.03 11 12719.93 36 2521.06 12 21723.30 24 Cover in TNHS Target Potential Natural 54.85 1 4128.36 21 204.64 3 7263.08 20 2118.66 10 13769.59 15 Cover in TNHS Target Total TNHS Target 492.23 8 9323.26 47 1054.67 14 19983.01 56 4639.72 22 35492.89 39

18 Humber River State of the Watershed Report – Terrestrial System

While the percent forest cover in the Humber River watershed is higher than in more urbanized TRCA watersheds such as the Don (9%) and the Highland (6%), it is still low considering that historically, it was probably closer to 90%. Forest cover has actually increased slightly in the 20th century due to reforestation on the Oak Ridges Moraine and a reduction in the intensity of agricultural use on the ORM resulting from the abandonment of lands as well as improved practices. Now with urban expansion, the trend is again shifting towards a reduction in the amount of forest cover in the Humber River watershed.

From the remotely-sensed aerial photos (2002) it has been determined that wetlands in the Humber cover 1401 hectares. This accounts for only 1.6% of the total watershed area and includes wetland such as marshes, thicket swamps, bogs and shallow ponds. Historically, wetlands in this region would have covered anywhere between 11 and 16 percent of the total watershed area (Environment Canada, 1986). Treed swamps although wetlands, are typically classified as forest habitat during the remote sensing exercise and are treated as forest cover for landscape analyses due to their contribution to interior forest values, and the difficulty in discerning treed wetlands from forests on the aerial photographs. Therefore we may be underestimating the total area of wetlands.

Only a very small portion of the Humber River watershed in pre-settlement times supported native meadow communities such as tallgrass prairie, savannah and sand barren communities. These communities largely being dependent on natural disturbances such as: forest fire, disease or pest outbreaks and blow downs. For this reason large areas of open habitat do not naturally occur in this bio-region therefore the maintenance of such open habitat and associated fauna and flora species would require a high degree ongoing management. The majority of meadows in the watershed are a result of human influence on the landscape (cultural meadows). Cultural meadows cover 9603.8 hectares, or 10.6% of the total watershed area. There still remains savannah habitat in the Humber watershed at Lambton Park. These habitat types are intermediate stages between old-field and sand barren, a natural vegetation type that probably occurred in forest openings on dry, sandy soil on the moraine and possibly along the Iroquois Shoreline in the Humber River watershed. True tallgrass prairie and oak savannah occur on the Oak Ridges Moraine to the east of the TRCA jurisdiction, in the vicinity of Rice Lake.

Beach and bluff habitat also includes coastal habitats that do not correspond to any of the other major habitat type categories. This category includes dynamic communities such as natural beach, coastal dunes, barrens and bluffs. In the Humber watershed, only 0.5 hectares of the watershed has been classified as beach/bluff habitat. Although one would expect this category to represent only a small fraction of the watershed, it is possible that through further ground-truthing in the watershed more beach/bluff habitat would be identified.

19 Humber River State of the Watershed Report – Terrestrial System

Table 6 Watershed Report Card Rating - Quantity of Natural Cover Objective: Protect, restore and increase the amount of natural cover. Overall Rating

C

Indicator Measure Target

- Quantity of natural Portion of total watershed area - protect, secure and restore cover with natural cover existing and potential natural 32.2% cover through various methods (planning and policy framework, stewardship, advocacy etcetera) to increase the percent natural cover to at least 39%; which is the minimum target defined using the Terrestrial Natural Heritage System methodology)

Portion of the total watershed Targets for forest cover will be area with forest cover developed through 18.3% implementation, as site conditions will dictate what communities are restored. Although we can acknowledge that based on historic conditions and the Humber’s location within a forest biome, most of the 39% TNHS target should be restored to forest.

The overall rating for quantity of natural cover was determined to be a ‘C’ in the watershed based on the current amount of 32%. This grade is determined based on how much natural cover is in the watershed. These grades are broken down as follows: 0 - 10% = F grade, 11 - 20% = D, 21 - 40% = C, 41 - 60% = B, greater than 60% = A.

4.2 Vegetation Community and Species Levels - Results of Field Inventories

Within the Humber River watershed, terrestrial habitats are associated with five broad physiographic regions: the Niagara Escarpment, Oak Ridges Moraine (ORM), the South Slope, the Peel Plain and the Iroquois Sand Plain (Figure 6). The physiographic regions define the character of the vegetation communities that can develop within an area.

20 Humber River State of the Watershed Report – Terrestrial System

The Humber River watershed spans two floristic regions, the Great Lakes – St. Lawrence Mixed Forest Zone and the Carolinian Forest Zone. The dominant tree species that characterize the Great Lakes-St. Lawrence Zone include sugar maple (Acer saccharum ), white ash ( Fraxinus Americana ), American beech ( Fagus grandifolia ), white pine ( Pinus strobus ) and eastern hemlock ( Tsuga canadensis ), although other species associations do occur where conditions permit. The Carolinian Zone is only represented by a small proportion of land in the southern parts of the watershed. Black Oak Savannah can be found in areas such as Lambton Park and High Park (not actually in the watershed but lies along the eastern watershed boundary). In addition, these areas also support a few species with Carolinian affinities, such as sycamore (Platanus occidentalis ), shagbark hickory ( Carya ovata ) and wild lupine ( Lupinus perennis ).

While the South Slope and Peel Plain areas are largely dominated by agricultural and urban uses, the ORM and Niagara Escarpment have more natural cover. Several outstanding remnant natural areas occur within the Humber headwaters, and, where the Humber River feeds into Lake Ontario, a large coastal marsh. The watershed contains a high diversity of species including a large number of species of concern (Appendix D and E), partly due to the combination of characteristic northern and southern Ontario conditions, the physiographic regions, the variety of habitat types and the presence of relatively large patches of mature, remnant forest.

Selected descriptions based on physiographic regions and field inventories from various sites are provided below to add some detail to the previous broad characterization of the existing conditions in the watershed (flora and fauna, and vegetation community lists appear in Appendices C, D and E. Terrestrial field inventories have been completed for approximately 40% of the Humber River watershed. The reference to provincially or locally significant wetlands is based on the federal/provincial evaluation system that classifies wetlands as either nationally, provincially, regionally or locally significant areas (OMNR, 1994).

Oak Ridges Moraine

The Humber headwater areas along the Oak Ridges Moraine contain the larger forests blocks found in the watershed. The largest natural cover ‘cluster’ is found in the most northwestern portion of the watershed in the Main Humber in the area of Centreville Creek, Palgrave and Albion Hills Conservation Areas. This area supports some of the highest quality natural habitats in the watershed, including vegetation communities ranging from dry coniferous plantations, sandy meadows, mature sugar maple forests with small kettle wetlands, and ponds surrounded by coniferous swamp. As high quality and relatively intact remnants of the natural system, they can serve as reference sites for the improvement of the target terrestrial natural heritage system for the southern and central reaches of the watershed.

Provincially Significant Wetlands (PSWs) and Wetland Complexes have been identified and inventoried and, in the headwater region, include the Eaton Hall - Mary Hackett Lakes Wetland Complex, Philips - Bond - Thompson Wetland Complex, Centreville Creek Wetland Complex, Widgett - Innis Lakes Wetland Complex, King - Vaughan Wetland Complex, and the Black Duck Wetland Complex .

21 Figure 6 Physiographic Regions Humber River State of the Watershed Report – Terrestrial System

The PSWs on the moraine within the watershed are noteworthy for their kettle bogs, high quality kettle lakes, and high concentrations of sensitive flora and fauna species. Natural heritage field inventories conducted by TRCA and OMNR staff biologists have revealed that these remnant sites encompass a high diversity of vegetation communities featuring shallow marsh, thicket swamp, and deciduous, mixed and coniferous forest swamps. The coniferous swamps are cool, shady habitats usually dominated by white cedar. Some contain regionally uncommon associations of balsam fir, white spruce and tamarack, which are communities with a strong boreal (northern Ontario) character. This forest-wetland combination with boreal affinities is particularly evident at Ballycroy Wetland.

The headwater wetland complexes also support several species and vegetation communities of concern (L1 to L3 ranking species). Fauna of concern present in these high quality areas include many wetland-dependent fauna such as sora, least bittern, wood duck, bullfrog, grey treefrog, and wood frog, and upland forest and meadow/successional species such as barred owl, ovenbird, bobolink and grasshopper sparrow. Vegetation communities of concern identified in the headwater areas include a tamarack-leatherleaf treed kettle bog (BOT2-1; ranked at L1), organic willow thicket swamp (SWT3-2; L3), broad-leaved cattail organic shallow marsh (MAS3-1A; L3), and several submerged shallow aquatic communities (SAS1; ranking L2- L3).

The kettle lakes in the Humber River watershed are noted for their rich aquatic plant communities, including flora of concern such as water-weed ( Elodea canadensis ), fragrant white water lily ( Nyphaea odorata ) and coon-tail ( Ceratophyllum demersum ). The kettle bogs support flora of concern such as tamarack ( Larix laricina ), leatherleaf ( Chamaedaphne calyculata ) and bog buckbean ( Menyanthes trifoliata ). The smaller kettle wetlands support flora of concern such as water horsetail ( Equisetum fluviatile ), winterberry ( Ilex verticillata ), and cinnamon fern ( Osmunda cinnamomea ).

South Slope

The South Slope includes some relatively high quality valley land such as the Nashville Tract, Cold Creek and the Provincially Significant King-Vaughan Wetland Complex. Outside of these areas, natural habitats on the South Slope are highly fragmented with small upland forest patches scattered throughout the largely agricultural landscape. Cedar swamps and meadow marshes appear where there is groundwater seepage and are associated with flora species of concern such as marsh pennywort ( Hydrocotyl americana ), gold thread ( Coptis trifolia ), and golden saxifrage ( Chrysosplenium americanum ). Ten sites have been recently surveyed by TRCA on the South Slope portion of the watershed . They support such sensitive fauna species as ovenbird, ruffed grouse, long eared owl, black-billed cuckoo and black and white warbler. Flora species of concern include cinnamon fern ( Osmunda cinnamomea ), nodding wood reed (Cinna latifolia ), and Indian cucumber-root (Medeola virginiana ).

23 Humber River State of the Watershed Report – Terrestrial System

Peel Plain

The Peel Plain physiographic region is characterized by land that is mostly flat or gently undulating with the exception of the ravines that carry streams flowing to Lake Ontario. The soils in this region are heavy and somewhat impermeable, especially in areas affected by temporary glacial melt-water ponding during the ice retreat. They are, however, highly fertile and desirable from an agricultural standpoint and most of the Peel Plain is still farmed.

Seven sites situated on the Peel Plain have been recently surveyed by the TRCA, including a large site at Kortright Centre and Boyd. This area is unique as it is the largest southern expanse of forest and despite the urbanization that has happened to the south, east and west this area is still able to support many species and vegetation communities of regional concern. South of this many natural areas are highly fragmented and are no longer able to support these species. In other sites where surveys have been completed (e.g. Claireville Conservation Area) fauna of concern such as wood frog and wood thrush have been discovered. Unless the terrestrial system is enhanced in this area of the watershed, the viability of these species is questionable.

Iroquois Sand Plain

The Iroquois Sand Plain runs as a narrow band along the lower portion of the watershed (below Hwy 401). The soils are largely sand to sand loam with isolated deposits of clay. Largely developed, little remains of the Carolinian and prairie habitats that would have once dominated the landscape here. Vegetation communities such as SBO1-c (Hard Fescue Sand Barren), TPS1-1 (Dry Black Oak Tallgrass Savannah) and FOD1-3 (Dry Fresh Black Oak Forest) and species like butternut ( Juglans cinerea ), skunk cabbage ( symplocarpus foetidus ), wild lupine ( Lupinus perennis ssp perennis ) and big bluestem ( Andropogon gerardii ) elude to the unique character that this area would have once contributed to the larger watershed.

Coastal Area

The Humber River watershed flows into Lake Ontario and the portion of the watershed around the mouth is considered a coastal area. The Humber Marshes formed here, now one of the few remaining coastal marsh areas along the north shore of Lake Ontario. However, like other Lake Ontario coastal marshes, the amount of vegetation cover declined significantly during the second half of the twentieth century, with emergent marsh being replaced by mudflats and open water. A wide array of factors are possible causes this decline, including persistently high water levels and carp activity.

There are no dynamic beach-bar communities found at the mouth of the river due to the presence of the breakwall in Lake Ontario that runs a short distance out from the shoreline. These communities rely on wave and wind action for their development and continued success. Shoreline beach and swale communities are becoming increasingly rare in the landscape due to hardening of shoreline areas. Further upstream of the mouth there are several marshes, open water and swamp communities.

24 Humber River State of the Watershed Report – Terrestrial System

Although many of these communities are dominated by non-native species, the open water areas are impressive for the Lower Humber and contain some sensitive flora species such as fragrant white water lily ( Nymphaea odorata ), lakebank sedge ( Carex lacustris ) and river bulrush (Bolboschoenus fluviatilis ).

The vegetation in the Humber Marshes and the vegetation that makes the Humber Bay West and High Park connection is extremely important for migrant birds. These areas are important staging areas for birds as it is the last stop or the first stop for birds that cross Lake Ontario.

Indicator Species

The lists of indicator species reported on in the 2000 Humber River watershed report card were developed using a combination of field-collected and remote-sensed information. Indicator species, in the absence of a complete inventory of species and communities, can provide a rough measure of the condition or ‘state of health’ of the watershed. However like any list, it merely indicates a presence or absence of species and does not consider abundance. It is presence along with abundance that indicates a healthy and functioning terrestrial system because species abundance is closely tied to natural cover quality, distribution and quantity. Therefore, interpretation of these lists must consider that indicator species were used here as a simplification to convey the state of biodiversity in the Humber watershed.

There are 25 flora and 25 fauna indicator species that were selected in 2000 as being representative of a range of habitat types, and could easily be identified by volunteers through the TRCA’s Terrestrial Volunteer Monitoring Program. Appendix A contains the complete set of lists of indicator species for each of the Humber River subwatersheds that have been generated through a combination of volunteer and TRCA biologist field collected data.

The data that was used in this interpretation was dated from 1996 to 2005. As was expected the Main and East Humber are very close to approaching the full suite of fauna indicator species, with the West Humber falling close behind. This would be indicative of the greater amount of natural cover in these subwatersheds, and the intensive agricultural history and increasing urbanization of the West Humber. In the Main Humber 25 of the 25 fauna indicator species were found and in the East there are 24 of the 25. The West Humber was in the middle range in terms of supporting the fauna indicator species with 19 present. In the largely urban Lower Humber and Black Creek, there is a marked decrease in the number of indicator species present. In the Lower there are 10 of the 25 fauna species represented and in the Black Creek there are seven .

There is a noticeable difference between flora and fauna species presence in these subwatersheds. The number of fauna indicator species being observed are much lower than flora indicator species. This can be explained by the fact that fauna are more sensitive to human impacts than flora (e.g. predation by cats and repeated flushing by people and pets). Flora, being less mobile, tend to persist longer in these unfavourable conditions. Table 7 summarizes the results regarding observations of flora and fauna indicator species in Humber subwatersheds.

25 Humber River State of the Watershed Report – Terrestrial System

Historically, most species would have been found throughout, except for a few species with some restrictions e.g., Meadow species, prairie species.

Table 7 Observations of Indicator Species in Humber River Subwatersheds (1996 - 2005) Parameter Subwatershed Main East West Lower Black Creek Humber Humber Humber Humber Fauna Indicator 25/25 24/25 19/25 10/25 7/25 Species Flora Indicator 24/25 23/25 21/25 19/25 18/25 Species

4.3 Biological Threats

Invasive Alien Species

Invasive species are recognized as one of the top five threats to biodiversity in the province of Ontario (OMNR, 2005). Many species and communities present in the watershed are vulnerable to invasive species, particularly forest herbs. In the Humber River watershed, a good proportion of the terrestrial communities that were recently inventoried have severe infestations of invasive alien plants. Within the watershed, garlic mustard (Alliaria petiolata ), an aggressive invasive forest herb, is already present in the forests, and European buckthorn (Rhamnus cathartica ), an invasive shrub has dominated many of the isolated forest patches throughout the study area. Also, aggressive non-native wetland species such as purple loosestrife ( Lythrum salicaria ) and common reed grass ( Phragmites australis ) now dominate several of the wetland communities. These aggressive species out compete native shrubs and saplings which lowers resident biodiversity and endangers the long term viability of the forest itself. Similarly, forest birds nesting in a forest under storey dominated by Tartarian honeysuckle, have been shown to be more predated upon than if they had been nesting in native shrubs that provide more protection from would be predators.

Extremely aggressive invasive species such as the recent introductions of the Asian long- horned beetle and emerald ash-borer have shown both the potential ecological impacts of invasive species, and the economic repercussions that follow. These two species have drawn much media attention due to the very obvious nature of their infestation, the speed at which they have spread and the obvious economic impacts they could pose for our forestry industry.

The control and management of invasive alien species is recommended as a means to improve and enhance the native biodiversity and the quality of the local terrestrial system. In many cases, invasive plants will need to be dealt with before restoration work is carried out. Care should be taken to monitor the spread of invasive plants along trails in sensitive habitats and infestations should be removed as soon as they become established.

26 Humber River State of the Watershed Report – Terrestrial System

Climate Change

In planning for a healthy natural heritage system we must also consider the likely affects of climate change. What the exact changes will be to the climate across the watershed are still not certain, but we can predict that it will be warmer, precipitation patterns will be changed, and extreme weather events will be more frequent. Our natural system will be tested as species are forced to adapt to a changed climate or migrate elsewhere. An unhealthy natural system will be more vulnerable while a healthy and robust natural system will be better able to adapt to these future challenges. For instance, a larger, more robust terrestrial system will help to ensure for greater genetic variability and stock necessary for the unknowns. The current state of the terrestrial system in the Humber as based on the analysis in this report will not be resilient enough.

27 Humber River State of the Watershed Report – Terrestrial System

5.0 SUMMARY AND MANAGEMENT CONSIDERATIONS

Due to the continued loss of terrestrial natural cover and the intensifying land uses within the matrix, the quality distribution and quantity of the terrestrial system in the watershed continues to decline. That quantity distribution and connections between high quality, or core habitat patches in the watershed is currently insufficient to support viable populations of species and communities.

The losses in natural cover in the watershed have lead to a loss in system function. This is evidenced by the decline in species. A good portion of the fauna and flora species occurring in the Toronto region have ecological or behavioural requirements that are compromised within an urbanizing landscape. Within a 25-year time frame, numerous sensitive species and communities have been lost from the watershed and many that have persisted have severely declined in health. These declines can be attributed to the continual and cumulative losses of terrestrial natural cover in the area, and the negative pressures imposed on the remaining terrestrial system by the surrounding urban land uses (e.g., invasive species, changes in hydrology, pollution, roving pets, inappropriate recreational uses, over use, etc.). One can expect that the sensitive species that are still present in the study area today will also disappear unless action is taken to implement the target system and TNHS strategy thereby improving the health and functioning of the existing system.

Securing an appropriate land base for an improved natural heritage system (such as the target system identified in the TNHS Strategy) is critical to mitigate the negative effects that are expected from future urbanization. By restoring an expanded terrestrial system, and following the objectives to improve the quality, quantity and distribution of existing habitats, terrestrial biodiversity will be more able to withstand the impacts of the highly urbanized matrix and will be more resilient in light of the unknown. The enhancement of the terrestrial system within the watershed will benefit other watershed components, such as the aquatic system, water quality and quantity, air quality, and will provide more opportunity for nature appreciation and recreation in the area.

A robust natural system is needed not only for biodiversity and the provision of ecosystem services (clean water, air, places to recreate in), but also to allow for a more resilient system in face of the unknown. In our region, we may face certain biological threats whose impacts are still unknown (e.g., changing climate and severe weather events, invasive species such as the Asian Long Horn Beetle, pollution, etc.). Increasing the amount and quality of terrestrial cover will help to create a more resilient system. Regarding the current state of the terrestrial system features remaining in the watershed, the following actions are recommended:

1. Protect and enhance existing terrestrial system features remaining in the watershed.

- Control and manage the spread of existing invasive alien plant species. - Secure all remaining habitat patches in the watershed to the extent possible.

28 Humber River State of the Watershed Report – Terrestrial System

2. Implement the TNHS strategy and target terrestrial system in the watershed by protecting the land base and restoring/enhancing habitat wherever possible over the next 100 years.

- Increase the size, improve the shape, and maximize forest interior values of existing terrestrial habitat patches. - Prioritize restoration efforts to buffer the known locations of sensitive vegetation and species. - Maximize connections between existing features, plan for species movement corridors; focus on restoring east-west connections on tableland where possible. - Restore old fields and manicured areas to forest and wetland communities where possible. - Recovery species and communities lost from the system.

3. Mitigate the negative effects of the matrix (surrounding land use).

- Encourage the preservation and care of urban trees and increase urban tree canopy through planting of native species. - Encourage the naturalization and the use of native plants on industrial properties and public lands wherever possible. - Encourage native species plantings on private lands. - Limit public access to certain areas within the system where sensitive species and communities exist. - Ensure that proposals for trail development take the locations of sensitive species and communities into consideration to mitigate all potential threats. - Use signage to identify formal trails and sensitive areas that should be kept free of public use. - Restore new areas to address recreational demands. - Control roving pets (cats and dogs) from residential areas, keep dogs on leashes and cats indoors during the bird breeding season. - Control encroachment into natural areas. - Control and manage the spread of non-native invasive species.

By protecting and restoring the ability of natural systems to carry out ecological functions within a developed landscape such as the Humber River watershed, there will be less need for costly maintenance of infrastructure, as well as cost savings from taking a preventative approach rather then relying on remedial solutions.

29 Humber River State of the Watershed Report – Terrestrial System

6.0 REFERENCES

Environment Canada, Inland Waters and Lands Directorate. 1986. Wetland Distribution and Conversion in Southern Ontario, Working Paper No. 48. Minister of Supply and Services Canada.

Kilgour, B. 2003. Landscape and patch character as a determinant of occurrence of eighty selected bird species in the Toronto area. A report prepared for the TRCA. Jacques-Whitford Ltd.

Lee, H., W. Bakowsky, J. Riley, J. Bowles, M. Puddister, P. Uhlig, S. McMurray, 1998. Ecological Land Classification for Southern Ontario: First Approximation and it’s Application. SCSS Field Guide FG-02, Ontario Ministry of Natural Resources; Toronto, Ontario.

Metropolitan Toronto and Region Conservation Authority. 1997. Legacy: A Strategy for a Healthy Humber . Prepared for the Humber Watershed Task Force.

Ontario Ministry of Natural Resources, 1994. Ontario Wetland Evaluation System - Southern Manual, 3 rd Edition.

Ontario Ministry of Natural Resources, 2005. Protecting What Sustains Us: Ontario’s Biodiversity Strategy.

Toronto and Region Conservation Authority, 2000. A Report Card on the Health of the Humber River Watershed , Humber Watershed Alliance, Toronto, Ontario.

Toronto and Region Conservation Authority. 2003a. Terrestrial Natural Heritage Program Data Collection Protocol, Draft.

Toronto and Region Conservation Authority, 2005. Data Collection Methodology, Draft.

Toronto and Region Conservation Authority, 2007a. Evaluating and Designing Terrestrial Natural Heritage Systems.

Toronto and Region Conservation Authority. 2007b. Listen to Your River – A Report Card on the Health of the Humber River Watershed. Prepared for the Humber Watershed Alliance.

Toronto and Region Conservation Authority, 2007c. Toronto and Region Terrestrial Natural Heritage System Strategy, Final Draft.

30 Humber River State of the Watershed Report – Terrestrial System

APPENDIX A INDICATOR SPECIES FOR HUMBER RIVER SUBWATERSHEDS

Fauna Indicator Species for Humber River Subwatersheds

Subwatershed Fauna Indicator Species Main Humber American woodcock eastern wood pewee savannah sparrow wood frog ovenbird green frog northern spring peeper scarlet tanager bull frog striped chorus frog swamp sparrow grey treefrog northern leopard frog green heron eastern chipmunk American toad Virginia rail mink wood duck bobolink ruffed grouse pileated woodpecker eastern meadowlark porcupine eastern screech owl East Humber American woodcock eastern wood pewee savannah sparrow wood frog ovenbird green frog northern spring peeper scarlet tanager grey treefrog striped chorus frog swamp sparrow eastern chipmunk northern leopard frog green heron mink American toad Virginia rail ruffed grouse wood duck bobolink porcupine pileated woodpecker eastern meadowlark eastern screech owl West Humber American woodcock eastern wood pewee savannah sparrow wood frog ovenbird green frog northern spring peeper swamp sparrow eastern chipmunk striped chorus frog green heron ruffed grouse northern leopard frog bobolink porcupine American toad eastern meadowlark wood duck pileated woodpecker eastern screech owl Lower Humber northern leopard frog eastern wood pewee savannah sparrow American toad green heron green frog wood duck Virginia rail eastern chipmunk eastern meadowlark Black Creek American woodcock eastern wood-pewee savannah sparrow American toad eastern meadowlark green frog eastern chipmunk

31 Humber River State of the Watershed Report – Terrestrial System

Flora Indicator Species for Humber River Subwatersheds

Subwatershed Flora Indicator Species Main Humber marsh marigold swamp milkweed white oak Jack-in-the-pulpit spotted Joe Pye weed riverbank wild rye narrow-leaved spring beauty barber-pole bulrush Christmas fern white trillium greater bur reed zig-zag goldenrod foam flower common arrowhead winterberry star flower black-eyed Susan eastern hemlock Michigan lily spreading dogbane white pine turtlehead fire weed white cedar East Humber marsh marigold swamp milkweed riverbank wild rye Jack-in-the-pulpit spotted Joe Pye weed Christmas fern narrow-leaved spring beauty barber-pole bulrush zig-zag goldenrod white trillium greater bur reed winterberry foam flower common arrowhead eastern hemlock star flower black-eyed Susan white pine Michigan lily spreading dogbane white cedar turtlehead fire weed West Humber marsh marigold swamp milkweed riverbank wild rye Jack-in-the-pulpit spotted Joe Pye weed Christmas fern narrow-leaved spring beauty barber-pole bulrush zig-zag goldenrod white trillium common arrowhead winterberry foam flower black-eyed Susan eastern hemlock star flower spreading dogbane white pine Michigan lily white cedar turtlehead Lower Humber marsh marigold swamp milkweed white oak Jack-in-the-pulpit spotted Joe Pye weed riverbank wild rye narrow-leaved spring beauty barber-pole bulrush zig-zag goldenrod white trillium common arrowhead eastern hemlock foam flower spreading dogbane white pine Michigan lily big bluestem white cedar turtlehead Black Creek Jack-in-the-pulpit swamp milkweed white oak narrow-leaved spring beauty spotted Joe Pye weed riverbank wild rye white trillium barber-pole bulrush zig-zag goldenrod foam flower common arrowhead eastern hemlock Michigan lily spreading dogbane white pine turtlehead big bluestem white cedar

32 Humber River State of the Watershed Report – Terrestrial System

APPENDIX B TERRESTRIAL SCORING SYSTEM FOR HABITAT QUALITY

Quality Ranking Criteria

Based on the zonal mean total patch scores (total score); which are made up of the individual scores for shape, size and surrounding (matrix) influence. RANKING CRITERIA

A Excellent Local Rank Habitat that is of the highest quality and Total score of (L1) habitat supports both regional species and vegetation (13 +) communities of conservation concern that are the most sensitive and the most threatened.

B Good Local Rank 2 Habitat of good quality that supports both Total score of (L2) habitat regional species and vegetation communities of (11-12.99) conservation concern

C Fair Local Rank 3 Habitat of a fair quality that supports or is either Total score of (L3) Habitat on the cusp of supporting both regional species (9-10.99) and vegetation communities of conservation concern.

D Poor Local Rank 4 Habitat of a poor quality that generally will not Total score of (L4) Habitat support regional species or vegetation (6-8.99) communities of concern, but will support urban species and vegetation communities of conservation concern

F Very Local Rank 5 A patch of very poor quality will generally only Total score of Poor (L5) Habitat support those species and vegetation (0-5.99) communities that are the most common, and not of either regional or urban concern.

Scoring for size, shape, and matrix influence of habitat patches

Score Size (ha) Forests & Size (ha) Shape Matrix Meadows Wetlands & (P/A) Beach/Bluff

1- very poor <2 <1 Q500 -100 to - 60 2- poor Q2 Q1 Q300 < -20 3- fair Q10 Q3 Q200 -20 to + 20 4- good Q50 Q10 Q125 > +20 5*- excellent Q250 Q20 Q100 +60 to 100 *A score for patches greater than 250 ha was included to reflect restored conditions where such patches were possible, and to allow for application of the model to other jurisdictions .

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