Conservation and Adaptive Management of the Rare Orchid Isotria medeoloides

1. LOGO Conservation and Adaptive Management of the Rare Orchid Isotria medeoloides Erin M. Higgins and B. J. Wicklow Department of Biology, Saint Anselm College, Manchester, NH , USA 03102 Results Introduction Students in the 2007, 2008, and 2009 classes of conservation biology (BI328) have participated in a long-term, state-wide adaptive management experiment with the goal to increase numbers of Isotria medeoloides, the small whorled pogonia. This rare orchid is found in eastern North America. Because it is listed as endangered or threatened in all states in which it resides, conservation efforts are underway to increase the size and condition (number of flower and seed capsules) of Isotria populations. Previous studies show light as a limiting factor in the growth and sustainability of Isotria. Populations in our study area have declined since 1987. Our objective is to increase the available light on populations of Isotria by canopy thinning (BI 328 students, Site C in 2007 and Site A in 2008). Here we compare tree density in a newly discovered Isotria population, Site F2, with Sites A and C. We measured the DBH (diameter at breast height) and basal area of trees in the 2009 plot to compare with 2007 and 2008 plots. Table 2. Total basal area of all trees in Isotria plots A, C, and F before tree removal. Figure 3. Isotria showing flower (left) and seed capsule (right). Figure 4. Stem counts of Isotria showing a decline in numbers in areas A and C. Populations F1 and F2 were discovered by BI328 students. Figure 1. Fisheye photograph of the 2007 Isotria plot for use in calculating percent canopy cover (left).Erin marking the north-south axis of the 20 x 40 meter plot. Figure 5.Total basal area of each tree species in the 20m by 40m plots. Methods Conclusions As of 2009, no new Isotria plants have appeared at Sites A (thinned in 2008) and C (thinned in 2007). Our results show that although there were more trees in the 2009 site F2, the total basal area was lower than in the 2007 and 2008 sites. Currently, the 2007 and 2008 studies are being monitored for effects of canopy thinning on Isotria population growth. Once the effects of the 2007 and 2008 thinning are evaluated. Sites F1 and F2 will be reviewed for possible canopy thinning. Saint Anselm students, the NH Natural Heritage Bureau, and The Nature Conservancy will continue to monitor these populations. Table 1: Basal area of each tree species in plots at Sites A, C, and F. Basal area = 3.142*(([dbh_val]/2)^2)*0.00064516*12.5 Figure 2. Sample plot layout. A grid of 10x10 m cells (A1, A0, B1, B0, Z1, Z0) used in the Isotria census includes one "target cell" (A0). Five 1x1 m herbaceous ve.getation plots are placed within the target cell. One 20x40 m plot, consisting of eight 10x10 m sub-cells, is placed around the target cell, extending 5 m on either side of it. Acknowledgements Thank you to Sara Cairns, NH Natural Heritage Bureau; Bill Nichols, NH State Ecologist/Botanist; Krista Helmboldt, The Nature Conservancy; Gordon Russell; The Piscataquog Land Conservancy Saint Anselm College Conservation Biology Students 2007-2009