Limitations of the point-count method for inferring stand-level species-resource relationships : a sampling simulation approach

• Main Author: Goodinson, Clive
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/10304

In this thesis, I suggest that only under special, simplified circumstances is the point-count method appropriate for deducing stand-level species-resource relationships. As a field evaluation of the point-count method, I developed stand-level species-resource models for two woodpecker species, the red-naped sapsucker (Sphyrapicus nuchalis) and the northern flicker (Colaptes auratus). Compounding sources of uncertainty severely compromised the usefulness of this exercise in elucidating species-resource relationships. In response to the difficulties with the field data, I developed Sample Sim'on, a program that simulates the repeated sampling of a population of mobile, territorial organisms in a landscape with one or more resources. I show that the spatial distribution of resources, species behaviour, and sampling design can greatly affect the success rate with which species-resource relationships can be determined correctly (i.e., the sampling success rate). Realistic values for parameters describing these elements result in a very low sampling success rate, even when sampling effort is impracticably high. In addition, other variables that are not explicitly defined in Sample Sim'on, including those acting over larger spatial scales, can only add variance to species-resource data, further weakening sampling success.