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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

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.

LOGO

Figure 1. 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.

Table 1Table 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 5.Figure 5. Total basal area of each tree species in the 20m by 40m plots.

Figure 4. Figure 4. Stem counts of Stem counts of IsotriaIsotria showing a decline in showing a decline in numbers in areas A and C. Populations F1 and F2 were numbers in areas A and C. Populations F1 and F2 were discovered by BI328 students.discovered by BI328 students.

Figure 3. Figure 3. IsotriaIsotria showing flower (left) and seed capsule (right). showing flower (left) and seed capsule (right).

Introduction

Methods

Results

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.

AcknowledgementsAcknowledgementsThank 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

Table 2. Total basal area of all trees in Isotria plots A, C, and F before tree removal.

Species

Site C(Trees Removed in2007)

Site A (Trees Removed in

2008)Site F 2009

(No Trees Removed)  # trees Basal Area # trees Basal Area # trees Basal Area

White Birch 12.00 6.11 0.00 0.00 2.00 0.27Black Birch 13.00 0.63 4.00 2.11 132.00 0.88Red Maple 38.00 7.45 8.00 1.75 26.00 2.13White Pine 7.00 2.07 13.00 15.00 16.00 0.06Red Oak 7.00 5.20 16.00 10.34 0.00 0.00

Oak 0.00 0.00 6.00 4.70 3.00 0.55Hemlock 70.00 26.18 12.00 6.22 56.00 13.23

Beech 41.00 1.97 31.00 0.91 43.00 0.47Witch Hazel 25.00 0.54 74.00 0.51 14.00 0.02

Stump 0.00 0.00 0.00 0.00 3.00 9.80White Ash 0.00 0.00 1.00 0.35 2.00 0.57Unknown 5.00 0.01 0.00 0.00 4.00 0.11TOTAL 218.00 50.17 165.00 41.90 301.00 28.07

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.