Marc, If the field edges increase in their irregularity, then you might get an increase in perimeter with a decrease in area, so I would be careful about using perimeter as one of your measures. Depending on how many transects you have, you could potentially treat each transect as a 'belt' or rectangular representation of a portion of the field and estimate area in that method. Increasing the number of transects (just for estimating area, not herbivore use) would increase the accuracy of your estimate of area. This is essentially the foundations for finding the area under the curve in calculus. Hope that helps. Tim
>>> Marc Nutter <[email protected]> 6/22/2012 9:43 PM >>> Dear Ecologgers, I am currently designing an study that aims to assess the effectiveness of meadow encroachment management at Philmont Scout Ranch in northern NM and I'm looking for your input. This long-term field study will rely on participants of the Roving Outdoor Conservation School (ROCS) aged 16-20 to collect encroachment and pellet group count data every summer in established treatment and control meadows. The goals in this study are twofold: 1. Assess the effectiveness of meadow encroachment management 2. Provide ROCS participants with tangible examples of land management and conservation work The idea is to use pellet group counts as a proxy for relative visitation by wildlife and range animals. Baseline pellet group counts will be collected on belt transects, using t-posts as permanent endpoints. Measurements to quantify the area of the meadow would be taken next (see paragraph below). Meadows would then be treated by cutting down saplings that are invading the meadow, increasing the overall area of treatment meadows. Control meadows of similar area would also be identified and pellet group counts gathered. These will not only provide something to compare treatment meadows to, but also serve as a way to measure the rate of invasion of the surrounding woodland in the years to come. The invasion is inevitable due to the fire suppression management plan carried out here and practically everywhere else in the country. Belt transects would then be cleared of pellet groups so that when surveyed 6-12 months later, all pellet groups would be recent and give an accurate measure of relative visitation. The hypothesis is that relative visitation by large grazing mammals will increase in treatment meadows. Most of the methods (meadow encroachment treatment, belt transect pellet group counts) are drawn out and ready to go. The aspect of the study that is eluding me is how to quantify the change of meadow area with treatment. As of now, I have participants calculating two measurements per meadow: 1) the average change in width of the meadow by subtracting the distance from the t-posts to the newly established (treatment) meadow edge by its original distance and 2) percent change of meadow perimeter. I would prefer to calculate original and treated meadow area, but ideally all calculations could be made in the field with immediate results for the sake of student investment, pushing GPS off the table. Do you know of any way to calculate the area of an irregular shape with pencil, paper, and a calculator? Furthermore, in your opinion are my two measurements that I've described above adequate for what I'm trying to accomplish? Any thoughts on this topic are welcomed and greatly appreciated. Thank you for you time, Marc Nutter Conservation Coordinator for Environmental Education Philmont Scout Ranch - Cimarron, NM (575) 367-2281 ext. 1249 [email protected]
