Concerning my post about the proper way to determine the density of woody species in fixed plots, contributors to the discussion unanimously agreed that only species mostly rooted in a plot (>50% within plot) should be tallied. Otherwise, the true plot size is unknowable if species rooted outside the plot are included. Rebecca Weissinger provided a link to an excellent treatise on measuring and monitoring plant populations http://www.blm.gov/nstc/library/pdf/MeasAndMon.pdf ,which also discusses the importance of designing studies to meet management and sampling objectives and statistical analysis of collected data. Of course, as with any study, one must have a firm grasp on objectives before designing a study and the pros and cons of various methods that can be used, including limitations concerning time, effort, and funding constraints. I suspect that various aspects of designing vegetation studies have been discussed on and off in this forum already and will continue to be.
Thanks for everyone's input to my basic question about density measurements. It seems that much of the problem stemmed from the term "stem" being undefined in the protocol. Funny how the misinterpretation of one word can wreak so much havoc. -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[email protected]] On Behalf Of Palmer, Mike Sent: Monday, June 03, 2013 12:25 PM To: [email protected] Subject: Re: [ECOLOG-L] plot sampling for density For those of you interested in questions of sampling and analyzing vegetation, You are not alone! I will put in a plug here for the International Association of Vegetation Science (IAVS) - On the web: http://www.iavs.org/ On Facebook: https://www.facebook.com/#!/groups/iavs.org/?fref=ts --Mike Palmer, Oklahoma State University -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[email protected]] On Behalf Of Rebecca Weissinger Sent: Monday, June 03, 2013 9:54 AM To: [email protected] Subject: Re: [ECOLOG-L] plot sampling for density Any well-designed long-term monitoring program should include definitions of what is "in" and "out" in a plot. For a good discussion of density, see Chapter 8 Section F in Elzinga et al's Measuring and Monitoring Plant Populations, particularly Figure 8.3 for discussions of boundaries. http://www.blm.gov/nstc/library/pdf/MeasAndMon.pdf The protocol you are using is definitely unusual in counting stems that are rooted out of the plot. If this program is just starting out, by all means improve the protocol with definitions of stems and how to treat boundaries. However, it sounded to me like there is already a reasonably long history of data collection. If that is the case, I would attempt to analyze the data as is and keep the methods the same, as the value of a long-term dataset may outweigh an improved technique that would be unable to incorporate previous data. If the previous data are unusable because of the slop, then it is worth attempting to correct the problem. If you can use the old data but still want to improve the methods, one way to transition is to do both methods side-by-side for several years to get a "correction factor" that can be applied to previous years of data. As examples, the U.S. National Park Service Inventory and Monitoring program has many long-term monitoring protocols available that could be useful. https://irma.nps.gov/App/ProtocolTracking Try searching under Biological Integrity/Forest/Woodland Communities for examples.
