As an aside, if you're doing plots, it is better to establish a single reference point for each plot using the gps, and then record the location of each plant using horizontal surveying (e.g. bearing and distance of each plant from the reference point), than getting a GPS location for each individual shrub. That will give you a much higher relative precision for the location of each plant in relation to the others.
In fact, if you're only interested in the accuracy of these relative positions (let's say, if you're looking at plant spatial distribution), you might not even need the DGPS. All your points will have the same absolute position error from the GPS used for the reference point, but will still be very accurate in relation to each other. Best, Thiago S. F. Silva Instituto Nacional de Pesquisas Espaciais (INPE) On Sunday, October 28, 2012, Tim Farkas wrote: > Hi Ecologers, > > I'm planning a field study in which I need to achieve ~30cm precision in > marking the locations of shrubs in a mountainous landscape in southern, > coastal California. I have been told that differential GPS may be our > solution. There's a lot of stuff out there on the web, so I'm a little > overwhelmed with the apparent options. Also, when researching this a few > years ago, I read about needing permission from the government for this > kind > of mapping precision. Is that true? > > Can anybody provide a source of recommendations for DGPS units, caveats of > their use, etc.? > > Help much appreciated. > > Cheers, > > tim > -- > -- -- *Dr. Thiago Sanna F. Silva* Postdoctoral Fellow Remote Sensing Division - Instituto Nacional de Pesquisas Espaciais (INPE) São José dos Campos, SP - Brazil www.dsr.inpe.br Personal Webpage: www.thiagosilva.wordpress.com https://plus.google.com/101212496230661235420
