Update of the Metro Vancouver Sensitive Ecosystem Inventory


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Update of the Metro Vancouver Sensitive Ecosystem Inventory (20092014)
Technical Report
Prepared by: Josephine Clark, Metro Vancouver & Del Meidinger, Meidinger Ecological Consultants Ltd. December 2020

Executive Summary
In 2014 Metro Vancouver produced the region’s first Sensitive Ecosystem Inventory (SEI) in response to the need for up-to-date, standardized ecological information to support decision making. Polygon delineation relied primarily on 2009 orthophoto imagery. An update to that inventory was conducted in 2015-2018 using 2014 imagery. The purpose of the update was primarily to document ecosystem losses over the five-year period (2009-2014). Additionally, the update incorporated new mapping and fieldwork, and made corrections where necessary. Updating the SEI will ensure it continues to be an effective and relevant land use and conservation planning tool for the region.
In the update project, one Modified Ecosystem class was removed from the inventory—Seasonally flooded agricultural fields (FS) – because they were considered too ephemeral to be mapped consistently using only one set of imagery.
Spatial information and associated attributes are stored in an ArcGIS 10 geodatabase, including attributes to track changes from the 2009 inventory.
Analyses of the dataset shows that between 2009 and 2014 the region lost almost 1% (1,637 ha) of its 'Sensitive' and 'Modified' ecosystems (Table 1). Much of this loss (1,190 ha) was focused within the ‘regional core’ – the more urbanized southern part of the region that excludes the large parks and estuaries under Provincial management, watersheds and other higher elevation areas. This equals a loss of 3.4% of sensitive and modified ecosystems within the regional core in a 5-year period. A decrease in ecosystem quality of less than 1% was detected at both the region and regional core levels.

Region Regional Core

Sensitive Ecosystems (SE)

Original Loss % Loss

SEI (Ha) (Ha)

150,422

658

0.4%

25,028

421

1.7%

Modified Ecosystems (ME)

Original Loss

% Loss

SEI (Ha) (Ha)

28,254

979

3.5%

10,049

767

7.6%

Totals – SE and ME Original Loss SEI (Ha) (Ha)
178,676 1,637 35,077 1,189

Table 1 – Sensitive and Modified Ecosystem Loss for the Region and Regional Core

% Loss
0.9% 3.4%

This report is focused on the update methodology and any changes from the original SEI methodology. Users should refer to the 2014 SEI Technical report (Meidinger, Clark, and Adamoski, 2014) for further details about how the inventory was created.

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Contents
Executive Summary ........................................................................................................................................ i Introduction .................................................................................................................................................. 1
Change in Project Area.............................................................................................................................. 1 Changes to Classification System.............................................................................................................. 1 SEI Update Procedures.................................................................................................................................. 2 2014 Orthophoto Image Update Methodology........................................................................................ 2 Field Checking ........................................................................................................................................... 6 New Mapping Incorporated into SEI......................................................................................................... 6 New Land Cover Mapping......................................................................................................................... 6 Estuarine and Intertidal Mapping ............................................................................................................. 7 Quality Assurance - Overall....................................................................................................................... 7 Quality Assurance - Old Field .................................................................................................................... 7 Results........................................................................................................................................................... 8 Region and Regional Core ......................................................................................................................... 9 Loss of Forest Ecosystems....................................................................................................................... 10 Changes in Ecosystem Quality ................................................................................................................ 11 Improvements and Future Work ................................................................................................................ 12 References .................................................................................................................................................. 13 Appendices.................................................................................................................................................. 14 Appendix I: SEI Data Model..................................................................................................................... 14 Appendix II: Comparing 2009 and 2014 Land Cover Mapping ............................................................... 29
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Introduction
The Metro Vancouver SEI was initiated in response to the need for up-to-date, standardized ecological information for the region to facilitate conservation of important ecological areas through informed land use and conservation planning, and increased awareness of ecosystem presence and declines. The initial SEI was completed in 2013 based on imagery from 2009 and other available map data. The initial SEI was recently updated using imagery from 2014 in order to incorporate changes to mapped ecosystems after 5 years, i.e., to document the amount, rate and type of ecosystem loss. This report describes the update process and summarizes the results.
To ensure the Metro Vancouver SEI continues to be an effective and relevant land use and conservation planning tool, it must be kept up to date. The overall goal of the update project was just that—to update the inventory, primarily to detect removals from sensitive ecosystem categories over the five years. Using 2014 regional orthophotos, ecosystem polygons were reviewed, and any loss or disturbance was documented. Improvements to the original mapping were also made through incorporation of new and more detailed mapping from other organizations, error correction, and additional field work to confirm and inform mapping decisions.
The objectives of the update were as follows:
1. Identify areas of disturbance or other land use change using 2014 regional orthophotos and update the SEI polygon boundaries;
2. Update the SEI classification attributes based on new imagery; 3. Modify the SEI data structure to allow changes to be tracked; 4. Identify, update and document polygons with classification errors in original mapping; 5. Summarize the changes, particularly the amount and rate of loss of sensitive ecosystems over
time.
This report is focused on the update methodology and any changes from the original SEI methodology. Users should refer to the 2014 SEI Technical report (Meidinger, Clark, and Adamoski, 2014) for further details about how the inventory was created.
Change in Project Area
Abbotsford has returned to the Fraser Valley Regional District for its Parks function so Metro Vancouver no longer has responsibilities for conservation planning related to parks. For this reason, Abbotsford has been largely removed from the Metro Vancouver SEI. Some buffer areas around Regional Parks that fall on the Langley/Abbotsford border are still included.
Changes to Classification System
The initial SEI was conducted according to Provincial standards for mapping ecologically significant and relatively unmodified ‘Sensitive Ecosystems’, including wetlands, older forests and woodlands. In addition, important ‘Modified Ecosystems’ such as old fields and young forest were mapped1. Modified Ecosystems are younger and more human modified but still have ecological value and importance to biodiversity.
1 See the SEI Technical Report (Meidinger, Clark, and Adamoski, 2014) for more detail on the classification system
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However, at the start of the update, it became apparent that the Modified Ecosystem class: Seasonally Flooded Agricultural Fields (code: FS) was going to be problematic. There was not a good match in what appeared to be wet areas of agricultural fields in comparing the 2014 imagery to the 2009 imagery and the fieldwork that was conducted. There were several sites that were initially mapped as ‘FS’ that appeared completely dry in the 2014 and other Google Earth imagery. Many other areas looked wet in 2014 imagery but did not appear so last time (or not enough to digitize). There are other instances where the areas appear wet in both images, but the boundaries do not match up well. Due to concerns that this class would change too much between iterations or would require considerable additional imagery and field work to map accurately, the decision was made to remove the class from the inventory. It is an extremely modified ecosystem and was included as an “Other Important Ecosystem” by Ministry of Environment (2006) as the areas may, at one time, have supported moist forested and non-forested ecosystems, including wetlands, and in their present form are important to waterfowl in the winter months. However, the area of flooded field varies with winter rainfall and agricultural field modification and their ephemeral nature makes them challenging to map accurately.
SEI Update Procedures
The SEI Update incorporated four sources of information:
1. 2014 orthophoto image 2. Field checking 3. New ecosystem mapping from other organizations 4. New land cover mapping (2014)
A discussion of each of these follows. The update methodology detailed in this document was based initially on Axys (2005) and adjusted as required.
2014 Orthophoto Image Update Methodology
As the primary goal of the update was to detect change, the 2009 SEI polygons were overlaid on the 2014 image and each was inspected to see if change had occurred. Figure 1 outlines the workflow associated with decisions about change or no change to a mapped area and Figure 2 provides an example of spatial modification. The SEI database structure, including new fields added during the update, is provided in Appendix I.
During the update, various kinds of change were detected, including:
• Deletions: polygons that were disturbed to the point where they were no longer a Sensitive or Modified ecosystem. Polygons were attributed as to reasons for change and attributes modified accordingly. Deleted polygons remain in the database to allow for calculation of change.
• Reductions in size: polygons where a portion of the 2009 polygon was disturbed. Required digitizing change in polygons and attributing reasons for change.
• Reductions in condition: polygons where some disturbance reduced the condition, but the polygon still meets the minimum requirements for inclusion as a Sensitive or Modified ecosystem. Required modifying Condition field and attributing reasons for change.
• Correcting errors and making improvements in 2009 mapping: some errors were observed during the update process; new, improved ecosystem mapping datasets were occasionally made available from other organizations and were reviewed and incorporated; and some issues raised
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in the 2012 quality assurance process required correction. Polygons deleted due to error correction (i.e. they should not have been included originally) have been removed from the inventory as they are not needed for calculations. • Addition, deletion or condition change due to natural factors: addition due to restoration work or natural aging; deletion due to aging or change that could not be attributed directly to human disturbance (e.g. water level change affecting a wetland). Deleted polygons remain in the database to allow for calculation of change. Condition fields were modified where required. The level of polygon updating was much less in the mountainous northern region—it is largely made up of protected areas (the watersheds, Provincial Parks and Regional Parks), with limited public access. In this area, the update was focused on fixing issues noted in the 2012 quality assurance assessment and scanning for obvious evidence of change (e.g. avalanche, blow downs, any park or watershed infrastructure development).
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Figure 1- General Workflow

Site is inspected

ON SCREEN

IN THE FIELD

Change is required?

NO

YES

No changes required [Mod_Type] = N or NB.

Change is required?

YES

NO

Change [SmplTyp] to V (if P). [Mod_Type] = N or NB

Change is due to actual
change in the landscape?

Change is due to actual
change in the landscape?

NO (error)

YES

YES

NO (error)

Change any fields needed to correct error. Complete [Mod_Type] (‘I’ or similar). Change [SourceDate] and [EcoMapper] if changes were significant.

Complete [Mod_Type]. If deleted, also complete [LU_Change]. If fieldchecked, [SmplTyp] = V. Amend [SourceDate] and [EcoMapper] if polygon was changed but not deleted.

Change any fields needed to correct error. Complete [Mod_Type] (‘I’ or similar). Change [SourceDate] and [EcoMapper] if changes were significant. Change [SmplTyp] to V (if P).

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The following bullets outline how observed changes (actual and mapping error) were reflected in the database:
• The field [Mod_Type] was used to document type of modification conducted on the polygon. Codes and descriptions are provided in Appendix I. Multiple modification types were sometimes recorded for one polygon, e.g. actual disturbance plus correction of a mapping error.
• The field [Change] is a summary of actual change between 2009 and 2014, populated using the field [Mod_Type]. It records if a polygon was added due to natural change, deleted due to natural change, or deleted due to human disturbance.
• For polygons deleted due to disturbance, a new field named [LU_Change] was used to record the cause of ecosystem loss. If only a portion of the polygon was deleted, [LU_Change] was only completed for the deleted portion, not the remaining portion even if it was deleted due to a remnant assessment (i.e. deleted because the remaining portion falls below the minimum polygon size). [LU_Change] codes are provided in Appendix I. The associated field [LU_Change_Desc] – is used to provide a few words of description of the land use change observed, if needed. o For areas where multiple land use types caused the ecosystem loss, these were only separately digitized if it was relatively easy to do so and they were of a significant size. In instances where it was not practical to do so (e.g. a residential development with associated roads and lawns), the land use change type documented was the most dominant one.
• Field-checking: o If a polygon is field checked and nothing is changed, only the Amend fields – [AmendDate], [AmendMapper] and [AmendComment] - are completed, so as to record when the field check occurred (i.e. it wasn't when the polygon was first mapped) o If a polygon is field checked and the polygon is deleted as a result, only the Amend fields are completed, so as to record when the field check and deletion occurred o If a polygon is field checked and the classification is amended as a result, the Amend fields are completed to document the field checking, any changes are made to the classification fields, and the [SourceDate] and [EcoMapper] fields are changed to new date and mapper.
• If a polygon is checked and classification or disturbance fields are changed, [EcoMapper] and [SourceDate] are amended to the new mapper and date
• If a polygon is checked and deleted (due to actual disturbance or mapping error), [EcoMapper] and [SourceDate] remain with the original info. [AmendDate] and [AmendMapper] are completed so that there is a record of when the polygon dropped out of the inventory
Additional points to note: • Before the update, a new field named [SEI_PolyNbr2009] was created to store the original SEI Polygon Number and provide a link to the previous version of the database. [SEI_PolyNbr] will only differ from [SEI_PolyNbr2009] in instances where amendments have split polygons and a new ID number is required to ensure each polygon has a unique ID. • Polygons that were reassessed and found to be too disturbed to be included in the inventory (i.e. a mapping error) were removed from the inventory entirely. • Calculations of loss can be made by selecting polygons with ‘DD’ in [Mod_Type] (alone or in combination with another code).
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• As with the original SEI, if calculations are being made based on particular component, the fields [WSize_SE1_BASIC], [WSize_SE2_BASIC] and [WSize_SE3_BASIC], provided the area of the polygon covered by each ecosystem component.
• Two fields were added to aid calculation of change in Quality between 2009 and 2014. [Adj09Qual] holds 2009 quality scores, if they were adjusted due to a reassessment in 2014. [Qual0914] indicates whether the polygon was assessed for quality in 2009 and/or 2014.
Field Checking
Four days of field checking was conducted in September 2016. One hundred and two polygons were checked. If errors were found in mapped polygons, they were corrected. The experience gained was also used to update other map polygons. For example, some areas of Estuarine marsh vs. meadow were checked in Richmond. Areas on the imagery that appeared to be slightly drier and potentially meadow were not found to be such in the field. It is likely that upper estuarine areas that historically may have been meadows are now behind the dykes.
New Mapping Incorporated into SEI
Several new ecosystem mapping projects were incorporated into the SEI during the update.
2013 Islands Trust Area Eelgrass Inventory – Mapping was mostly used ‘as is’, with a few exceptions:
• Some polygons were merged with adjacent polygons if they were very close together. • Some extremely small polygons were left out.
Although the minimum size of some resulting polygons falls below our official minimum (0.5 ha), the same approach was taken as with small TEM polygons – it has already been mapped so include, unless it’s extremely small (Rao et al., 2013)
Widgeon Marsh Regional Park – new TEM mapping of the wetlands at Widgeon Marsh (Schaefer and Page, 2015).
Iona Island – new TEM mapping for park (Page, 2011).
Grauer – new mapping provided by Ducks Unlimited Canada (with permission from City of Richmond).
Pitt Polder – new TEM wetlands mapping provided by Nick Page (with permission from Ducks Unlimited Canada).
New Land Cover Mapping
Land Cover mapping is used to determine the Landscape Context attribute which is one of three values used to determine Quality (see Meidinger et al., 2014). New high-resolution Land Cover mapping for Metro Vancouver (2014) was obtained to update the landscape context values in the SEI. The 2014 Land Cover classification was created with a slightly different methodology and an improved resolution (Ruan et al., 2017), as compared to the 2009 land cover classification used when creating the SEI initially.
To enable an assessment of change in landscape context between 2009 and 2014, it was necessary to compare the two land cover classifications to determine how significant differences between the two were, and whether differences could be attributed to actual change or methodological change.
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Sources of major difference between the 2010 and 2014 land cover classifications were: • Increased image resolution. 2010 was 10m and 2014 was 5m. • Incorporation of LiDAR data, where it was available in the region. This further enhanced the ability to detect small features. • Only ‘pure’ land cover classes. The 2010 land cover used some ‘mixed’ classes, e.g. Urban Mixed was used when buildings, paved areas, trees, grass and shrub occur in close proximity to each other and are not well defined. The increased resolution in 2014 meant these mixed classes could be removed.
Appendix II outlines the method used to compare the two land cover datasets and assess whether changes were likely due to the methodology, or actual change. The assessment exercise showed that actual change of vegetated to non-vegetated land covers was picked up well which was the primary concern for use in the SEI. It is likely that some change, positive and negative, was not captured due to the change in methodology. However, for use in the landscape context, land cover classes are generalized and similar classes (e.g. Buildings and Roads) are given the same landscape context ‘score’ within the analysis – this means that differences between similar classes between 2009 and 2014 will not affect the landscape context assessment. Given this, and the steps taken to refine detected change and only classify a subset as actual change, any errors or omissions are unlikely to be very significant.
This is likely to be somewhat of an ongoing issue, i.e., different imagery quality and methods of analysis will change the result of future updates.
Estuarine and Intertidal Mapping
Mapping of Intertidal mudflats and eelgrass, and Estuarine marsh and tidal flats, which are often partially or wholly submerged in orthophotos, are challenging to update without focused effort in the field. Mapping of these classes in the SEI has relied largely on the 2006 FREMP (Fraser River Estuary Management Program) Habitat Inventory work. For this update, changes were made when they were visible in the orthos but the SEI should not be used to assess or calculate change over time in these ecosystems. Recession in the brackish marshes of the Fraser River estuary is being studied by the Provincial and Federal governments, in-conjunction with others, and these sources should be referred to for this information. For more information, please contact the Coordinator of the South Coast Conservation Land Management Program, Eric Balke ([email protected]).
Quality Assurance - Overall
In this update, Josephine Clark conducted the update mapping and flagged some polygons for additional evaluation. Del Meidinger checked these polygons and scanned others to check the mapping – 820 polygons were given this additional review, which is 5% of the polygons reviewed (~11,500 polygons fall within the protected watersheds and provincial parks and were only scanned for change). The QA was used to update the mapping and was not a separate procedure post-mapping.
Quality Assurance - Old Field
The intention with the Old Field class is to capture a particular ecological state. Sites with welldeveloped herbaceous vegetation but with some shrubs and potentially a few young trees. This range in
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Update of the Metro Vancouver Sensitive Ecosystem Inventory