Terrestrial Ecosystem Mapping for Howe Sound Islands

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Terrestrial Ecosystem Mapping (TEM) for  
Howe Sound Islands – Bowen, Gambier, Keats, 
Anvil and Other Associated Islands 
 
 
 
for: 
 
Kate Emmings 
Ecosystem Protection Specialist 
Islands Trust Fund 
Suite 200 – 1627 Fort Street 
Victoria, BC,  V8R 1H8 
 
 
 
by: 
 
MADRONE ENVIRONMENTAL SERVICES LTD. 
1081 Canada Avenue, Duncan, BC,  V9L 1V2 
 
 
 
 
October 2, 2009 
Dossier 09.0096 
MADRONE 
 

Islands Trust Fund Page i 
Terrestrial Ecosystem Mapping – Howe Sound  October 2, 2009 
 
Dossier 09.0096 
MADRONE 
 
environmental  services  ltd.  
EXECUTIVE SUMMARY 
This report presents the results of Terrestrial Ecosystem Mapping (TEM) of the 
Howe  Sound  Islands,  which  are  situated  in  the  Coastal  Western  Hemlock  
(CWH)  biogeoclimatic  zone  of  southwestern  British  Columbia.  The  study  area  
covers  13,968  hectares  across  four  main  Islands  (Bowen,  Gambier,  Anvil,  and  
Keats)   located   at   the   entrance   to   the   Squamish   River,   between   Greater   
Vancouver and the Sunshine Coast Regional Districts. 
 
Terrain  and  ecosystem  mapping,  field  sampling  and  air  photo  interpretations  
were  completed  at  a  scale  of  1:10,000  using  the  appropriate  provincial  standards  
and  methods  (RISC  1996,  1998a,  2000,  2002,  and  2004).  The  original  polygon  
estimation  for  the  study  area  was  1,200  based  on  1:16,000  mapping  scale  and  a  
study area of 12,000 hectares. Our final product mapped a total of 2,017 forested, 
non-forested  and  anthropogenic  polygons  for  the  Howe  Sound  study  area,  
covering 13,968 hectares. 
 
Elevation  boundaries  for  the  study  area  range  from  sea  level  to  approximately  
900 m on Gambier Island (Mount Liddell), starting with the CWHxm1 at lower 
elevations,  the  CWHdm  in  the  upper  elevations,  and  only  the  highest  peaks  of  
the islands in the CWHvm2. These biogeoclimatic subzones or variants are very 
common  in  southwestern  BC,  covering  much  of  Vancouver  Island  and  the  
mainland coast. The temperature and climate in the CWHxm1, dm, and vm2 are 
generally warm and dry in the summer months with moist, mild winters (Green 
and Klinka, 1994). 
 
Soil  and  terrain  types  present  in  Howe  Sound today are influenced by historical 
glaciation events and contemporary erosion and deposition. The soils are mainly 
derived from morainal and colluvial deposits, and to a lesser extent, glaciofluvial 
and glaciomarine sources. The position of the islands combined with the range of 
elevations  and  terrain  sources,  lead  to  a  variety  of  vegetation  and  ecosystem  
types. 
 
The  typical  site  conditions,  such  as  soil,  terrain  and  climate,  combined  with  the  
interaction  of  vegetation,  animals  and  insects,  make  up  the  ecosystems  in  the  
CWHxm1,  dm,  and  vm2.  Site  modifiers  were  applied  to  the  TEM  mapcodes  to  
further describe atypical situations, such as shallows soils and steep slopes. 
 

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