Methodological and Operational Problems
Much is unknown about the Pacific Water Shrew because it is so rare. Its rarity makes it a difficult mammal to research. Much of this analysis is based on what researchers hypothesize to be true regarding the Pacific Water Shrew's habitat. These include the buffer regions; there is much argument between what the minimum required buffer distance from a stream should be when it comes to loggers, land developers, and environmentalists. Generalizations had to be made in order to do this project, which may under represent what occurs in real life.
One problem with this type of analysis is that the weighting scheme is subjective. Different people have different ideas on what is the most important factor when considering the Pacific Water Shrew's habitat. Some may say that anthropogenically-created factors such as urban areas, agriculture, and road networks are more important to consider than old growth forests and wetlands.
The park data does not give a detailed description. This could be problematic as some campgrounds are within a forested area, making it a suitable habitat for the Pacific Water Shrew, especially since camping is seasonal. Other campgrounds are similar to a field, which would make it a much less suitable habitat. The same problem applies to the park or sport field layer used to create the "lesser parks" layer. Some of these parks could be just a sport field or playground, while some are actual forested areas that are very suitable for habitat location. An example of this is Mundy Park, which is located in Coquitlam, B.C. where the Pacific Water Shrew was observed. There are sport fields at one end of the park, but amidst a reasonably sized wooded area (Lattik, 2001).
Road network data create another potential problem. Some roads have more traffic than other roads, such as highways versus side streets or roads used in rural areas. This results in different roads having differing amounts amounts of pollutant production and runoff (oil, gas, or garbage), with busier roads creating a more unsuitable area surrounding it and not so busy roads having less of an impact on suitability.
Different areas of the city will also have varying amounts of pollution production that can be harmful to the suitable habitat for the Pacific Water Shrew. An industrial area will produce more pollution than the suburbs of Vancouver; the suburbs of Vancouver will have more pollution produced than the suburbs of Langley, and so forth. Determination of locations that produce a significant amount of pollution is difficult. Urban centres versus industrial areas or sewage treatment plants, versus agricultural areas will produce different amounts of pollution at different times of the year. For example, in agriculture pesticides and fungicides are used most heavily in the summer season, while in the winter spraying does not occur for most farmers. Data regarding pollution is also difficult to retrieve because it does not promote the image of whomever produces it.
It is also difficult to determine where pollution would go due to complex drainage systems. The distance to suitable habitat from agriculture would probably be less upstream than it would be downstream, but research would have to be done at various points up and downstream of a particular location. It is also not so simple as looking at river drainage networks. The hydrogeology of the area must be examined to determine groundwater flow as well.
The region created based on the map produced from the SARA website is digitized, and approximate. Some locations show up as suitable near the edge of the ocean, which should probably not be the case since it is a fresh water mammal.
Jacquelyn Shrimer ~ jshrimer@sfu.ca ~ Geog 355