Demography of the Rare Orchid, Isotria Medeoloides (Orchidaceae) and Its Response to a Canopy Thinning Treatment

Isotria medeoloides, a North American Threatened Orchid: Fungal Abundance May Be as Important as Light in Species Management

“…While there are no data to support this assumption, Isotria seeds have been found to remain viable for decades in the soil, and an increase in fungal abundance could potentially trigger germination. Isotria seeds in soil in seed packets [53] As was shown in the two studies in New England [20,28], our research demonstrated the positive effect of thinning on the growth of individual plants (Figure 7), the positive relationship between canopy openness and growth (Figure 6), and the increase in fungal abundance in response to the death of the canopy tree at PRWI (Figure 8). Falb and Leopold [49] showed similarly positive relationships between light and plant size in Cypripedium candidum.…”

“…This resulted in a significant Thinning effect (z-value = 2.13, p = 0.03), but not a significant Relative Year effect (z-value = 1.92, p = 0.052) or Thinning χ Relative Year interaction (z-value = −0.54, p = 0.59). Long-term monitoring of Isotria has occurred at a several sites [20,28,38], but few longterm data have been published in peer-reviewed articles since Mehrhoff's studies [35,36]. Brumback et al [22] and Brumback [28] reported monitoring data as part of an experiment to determine if the decline of Isotria populations in New Hampshire was the result of increased shading as forests matured.…”

“…Fungi in the Russulaceae are considered obligately ectomycorrhizal with plants, and some can simultaneously form mycorrhiza. For Isotria, Long-term monitoring of Isotria has occurred at a several sites [20,28,38], but few long-term data have been published in peer-reviewed articles since Mehrhoff's studies [35,36]. Brumback et al [22] and Brumback [28] reported monitoring data as part of an experiment to determine if the decline of Isotria populations in New Hampshire was the result of increased shading as forests matured.…”

“…Unlike P. leucophaea , attempts to germinate Isotria seeds for the development of propagation protocols have not been successful, even though several attempts to germinate mature and ‘green pod’ seeds have been conducted across several institutions. The successful management of Isotria depends on developing protocols for maintaining or increasing the size of known populations, ideally through the use of enhanced flowering and seed production to increase the possibility of new plant recruitment, or through the emergence of dormant plants [ 20 ]. The most recent species recovery plan for Isotria was published in 2008 [ 21 ], and is currently being updated [Cherry Keller, USFWS, personal communication].…”

Impact of weather conditions on seasonal development, population structure and reproductive success on Dactylorhiza traunsteineri (Orchidaceae) in the Komi Republic (Russia)

“…But even taking into account numerous recent publications (e.g. Vakhrameeva, 2006;Blinova, 2008Blinova, , 2009Puchnina, 2017;Brzosko, 2002Brzosko, , 2003Pfeifer et al, 2006;Shefferson, 2006;Jacquemyn et al, 2007;Hutchings, 2010;Sletvold et al, 2010a;Van der Meer et al, 2016;Dibble et al, 2019;Stroh, 2019), many issues of orchid population dynamics are still poorly studied.…”