Ecohydrological controls on lichen and moss CO₂ exchange in rock barrens turtle nesting habitat

Abstract

Lichens and mosses are among the first organisms to colonize the open bedrock of eastern Georgian Bay, Ontario making them essential for primary soil formation and ecosystem succession, while also providing nesting habitat for turtle species‐at‐risk. However, the slow growing nature of lichen and moss makes them vulnerable to ecohydrological stresses caused by climate and land‐use change. In order to better understand how lichen and moss will respond to stressors, we examined which ecohydrological factors (e.g., near‐surface soil moisture and temperature) control the CO2 exchange of lichen (Cladonia spp.) and moss (Polytrichum spp.) on rock barrens, and the time of year growth primarily occurs. Net ecosystem productivity (NEP) was significantly greater in the wet period of the growing season than the dry, with an estimated difference of 0.7 μmol m−2 s−1 for lichen, 2.9 μmol m−2 s−1 for moss, and 2.5 μmol m−2 s−1 for a moss and lichen mix. These findings indicate that the wet portions of the growing season are critical for growth, while lichen and moss have little to no productivity during the dry period. Our results indicate that near‐surface soil moisture is an indicator of the CO2 exchange of lichen and moss, and this relationship varies among cover types. For the geographical regions where warm, dry conditions are expected to increase in duration and frequency with climate change, lichen and moss NEP will likely decrease, thus limiting the long‐term availability of nesting habitat for turtle species‐at‐risk.

Peat depth as a control onSphagnummoisture stress during seasonal drought

“…Given that both the magnitude and frequency of meteorological drought are expected to increase for peatlands due to climate change (Helbig et al, 2020) the differential response of shallow and deep peatlands are potentially far reaching. For example, while deep pristine peatlands will likely be resistant and resilient to drought, shallow peatlands such as younger and/or slow‐accumulating peatlands (Vardy et al, 2000), recently restored peatlands (Granath et al, 2016), and organic soils under moss and lichen mats on the upland rock barrens (Hudson et al, 2020; Moore et al, 2019) will be more vulnerable and conservation and potential adaptive management efforts may be necessary to maintain the carbon storage function of these sites. Given that peatland restoration has been emphasized as an important nature‐based solution to mitigate climate change (Humpenöder et al, 2020), our research also highlights the vulnerability of peatland restoration efforts in situations where the peat and moss layer are shallow (Grand‐Clement et al, 2015).…”

“…The wetland and peatland soil are mostly organic soil (peat) situated on a thin layer (0-5 cm) of mineral soil (Didemus, 2016). The surface cover of the ridges tends to consist of either small thin patches of mineral soil, moss cushions, lichen mats, or exposed bedrock (Hudson et al, 2020), while the intervening valleys more commonly consist of deeper mineral soil, ponds or deep and expansive peatlands.…”

Creating landscape‐appropriate habitat restoration strategies: success of a novel nesting habitat design for imperiled freshwater turtles

“…Because we paired the transplant plots with confirmed turtle nests, we had to move the lichen and moss in late June. It is possible that the moss transplants were moisture stressed given the dry conditions for 2 months following transplant (Hudson et al 2021) and were unable to recover in the fall. Conversely, lichens become dormant under dry conditions and can rapidly return to productivity when water becomes available.…”

Peat depth as a control on moss water availability during drought

“…Given that both the magnitude and frequency of drought are expected to increase due to climate change (IPCC, 2013) the differential response of shallow and deep peatlands are potentially far reaching. For example, while deep pristine peatlands will likely be resistant and resilient to drought, shallow peatlands such as younger and/or slow-accumulating peatlands (Vardy, Warner, Turunen, & Aravena, 2000), recently restored peatlands (Granath et al, 2016), and organic soils under moss and lichen mats on the upland rock barrens (Moore, Smolarz, Markle, & Waddington, 2019;Hudson, Markle, Harris, Moore, & Waddington, 2020) will be more vulnerable and conservation and potential adaptive management efforts may be necessary to maintain the carbon storage function of these sites. Given that peatland restoration has been emphasized as an important nature-based solution to mitigate climate change (Humpenoder et al, 2020), our research also highlights the vulnerability of peatland restoration efforts in situations where the peat and moss layer are shallow (Grand-Clement et al, 2015).…”