The relative photosynthetic contribution of old and new fronds of the wintergreen fern Dryopteris carthusiana, Ontario, Canada¹

Seasonal coordination of leaf hydraulics and gas exchange in a wintergreen fern

“…Evidence from our diurnal net carbon assimilation models shows that days sampled in April, October and November account for 58 % of the total net diurnal carbon assimilation estimates. Thus, these shoulder season months with no overstory deciduous canopy represent an important period of photosynthetic carbon gain for P. acrostichoides , along with other wintergreen ferns ( Goldblum and Kwit 2012 ).The wintergreen habit, while conferring the advantage of net positive carbon gain in the shoulder seasons, also comes with the liability of the respiratory costs of keeping foliage alive throughout the winter. The northern limit to the distribution of a wintergreen species would likely be constrained by the amount of time spent in below freezing temperatures, given that net carbon gain is strongly affected by T min .…”

“…This strategy allows photosynthesis to continue under higher light intensity conditions in the spring and fall when deciduous canopy leaves are absent ( Noodén and Wagner Jr 1997 ; Forget et al 2018 ). In a wintergreen Dryopteris , over 75 % of the total annual carbon gain occurs before canopy closure or after deciduous leaf senescence ( Goldblum and Kwit 2012 ). Despite the respiratory cost, maintaining leaves over winter gives access to light during the open canopy period which promotes carbon storage and early growth in the following season ( Chabot and Hicks 1982 ).…”

Reduced winter snowfall damages the structure and function of wintergreen ferns

“…The net emission of carbon from the damaged sections of leaves could be from respiration or decomposition (Howard and Howard, 1974; Atkin et al, 1997; McTiernan et al, 1997). Overwintering fronds are important sources of vernal carbon for wintergreen ferns (Tessier, 2001; Tessier and Bornn, 2007), contributing approximately 43% of annual carbon gain in deciduous settings (Goldblum and Kwit, 2012, 2013). This loss of photosynthetic surface area (Table 2) may result in decreased annual growth in these species (Fry and Phillips, 1977; Lee and Bazzaz, 1980).…”

“…Ferns with very thin fronds, such as Dryopteris intermedia (Fig. 3 and calculated from data in Goldblum and Kwit, 2012, 2013), may be the most susceptible to frost damage. The species‐specific nature of and the myriad factors that control frost hardiness in plants (Bannister, 1984; Bannister and Fagan, 1989; Bigras and D’Aoust, 1993; Griffith and McIntyre, 1993; Bannister et al, 2005; Naaf and Wulf, 2011; Diamond et al, 2012; Gusta and Wisniewski, 2013) offer multiple possibilities for the ecophysiological traits responsible for frost damage in these ferns.…”

“…These fronds only senesce once a new set of fronds forms when canopy trees leaf out (Tessier, 2008). Frost damage to the overwintering fronds may be important to these species because they provide important energetic and nutritional benefits to these plants (Minoletti and Boerner, 1993; Tessier and Bornn, 2007; Goldblum and Kwit, 2012, 2013).…”