I haven't worked through this mathematically, but could the average distance vary for the same value of density? I would think that the median could differ, but I'm not so sure about the average. The point-centered quarter method for estimating stem density relies explicitly on the square of the average distance (1/d2) to individual trees from the point. But, the assumption of that method is (I believe) that plants are randomly distributed in relation to one another, which of course may not be the case.
Mark D. -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[email protected]] On Behalf Of Basil Iannone Sent: Wednesday, April 25, 2012 8:40 AM To: [email protected] Subject: Re: [ECOLOG-L] estimating distance between points from density? Nic, Can you give us more context. Are you trying to use average distance as a predictor of some other variable? If so, why not just stick with density? Converting density to an average distance seems to me that you are just making up numbers, i.e., in reality the average distance could vary considerably for the same value of density. So it seems to me that your density measure is actually reflective of the level of precision that you collected your data at and should be used rather than average distance. On Wed, Apr 25, 2012 at 4:15 AM, Nic Charlton <[email protected]>wrote: > Hi Ecologgers, > > I am trying to estimate the average distance between flowers from > their density (flowers per square metre) and have not been able to > find a simple and satisfactory method for this. > > At first I assumed that if the flowers were distributed evenly, I > could use the square root of the density to find the number of flowers > in a straight line per metre, and use this to estimate the distance > between the nearest two flowers. > > Does any one know a better way to estimate average distance between > points or prey items (in my case flowers for foraging bees) from their > density (preferably without a lot of maths)? > > Thank you, > Nic Charlton > PhD student > University of Bristol, UK > > -- Basil Iannone University of Illinois at Chicago Department of Biological Sciences (MC 066) 845 W. Taylor St. Chicago, IL 60607-7060 Email: [email protected] Phone: 312-355-3231 Fax: 312-413-2435 http://www2.uic.edu/~bianno2
