Performance of late succession species along a chronosequence: Environment does not exclude Sphagnum fuscum from the early stages of mire development

Abstract

Questions: Sphagnum fuscum (Schimp.) Klinggr. is a characteristic species of the later stages of mire development. It is hypothesized that competition limits its success in earlier successional stages where higher mineral nutrient availability and wetter conditions favour species with a higher production rate and, therefore, a stronger ability to compete. We aim to quantify the importance of different site factors and the effect of neighbouring plants on the performance of S. fuscum.Location: A mire chronosequence from a land uplift coast towards inland on the Finnish side of Bothnia Bay, Baltic Sea. Methods:We transplanted S. fuscum to seven sites along a mire chronosequence for a period of two growing seasons. Neighbouring plants were removed from half of the locations/transplants. We measured several growth-related parameters, such as rate of photosynthesis, chlorophyll fluorescence (F v /F m ) and abundance of mosses.Results: Sphagnum fuscum samples did not survive in the recently exposed sandy shore stage and in fen flarks with extensive sedge cover. Photosynthesis and abundance of transplanted S. fuscum were highest in the wet meadows, the stages that immediately follow the sandy shore stage. Photosynthetic rate and F v /F m were low in the late succession bog site compared to the younger successional sites. The occurrence of neighbouring plants decreased the abundance of the transplanted mosses but improved the physiological state. The impact was similar throughout the successional chronosequence. Conclusions:The site factors favourable for rapid Sphagnum growth in general also favoured S. fuscum. The low photosynthesis, respiration and F v /F m of intact S. fuscum growing in its natural habitat compared to the surviving transplants in the younger sites suggests that in order to occur in its natural habitat, S. fuscum needs to allocate resources for photoprotective mechanisms. Our results indicate that under better environmental conditions, these resources can be allocated to the photosynthetic apparatus to increase growth.

Modelling the habitat preference of two key <i>Sphagnum</i> species in a poor fen as controlled by capitulum water content

“…Secondly, in habitats with a more persistently high moisture content, such as lawns and hollows, interspecific competition becomes important: it is acknowledged that species from such habitats generally have higher growth rates and photosynthetic capacity than hummock species (e.g. Laing et al, 2014;Bengtsson et al, 2016). Our results also agreed with this, as setting the growth-related parameters (i.e.…”

“…1b). The light levels were chosen based on previous investigation by Laine et al (2011Laine et al ( , 2015, which showed increasing A until PPFD at 1500 and no photoinhibition even at high values of 2000 µmol m −2 s −1 . The samples were allowed to adjust to cuvette conditions before the first measurement and after each change in the PPFD level until the CO 2 rate had reached a steady level, otherwise the cuvette conditions were kept constant (temperature 20 • C, CO 2 concentration 400 ppm, flow rate 500 µmol s −1 , impeller at level 5, and relative humidity of inflow air 60 %, although the relative humidity remained on average 81 % during the measurements).…”

Responses of peatland vegetation to 15‐year water level drawdown as mediated by fertility level

“…The resistance we observed is likely linked to bogs’ dependence on rainfall for both moisture and nutrients (Nijp et al., ) making especially hummocks naturally exposed to seasonal droughts and extremely nutrient‐limited conditions (Rydin & Jeglum, ). Bog vegetation is already adapted to survive in very restrictive conditions and can persist despite the WLD with adaptations such as nutrient recycling (Laine, Ehonen, Juurola, Mehtätalo, & Tuittila, ; Small, ). The mechanism of our treatment (lowering the water table from the peat surface and not controlling precipitation) and the hydrological regime of a bog (precipitation‐driven), may partly explain the resistance found for the ombrotrophic site.…”

“…Bog vegetation is already adapted to survive in very restrictive conditions and can persist despite the WLD with adaptations such as nutrient recycling (Laine, Ehonen, Juurola, Mehtätalo, & Tuittila, 2015;Small, 1972). The mechanism of our treatment F I G U R E 3 Response of different plant communities (Appendix S5: (2000, 2001, 2002, 2003, 2009, and 2016 (lowering the water table from the peat surface and not controlling precipitation) and the hydrological regime of a bog (precipitation-driven), may partly explain the resistance found for the ombrotrophic site.…”

Species-specific temporal variation in photosynthesis as a moderator of peatland carbon sequestration

“…The measured light levels were 2000, 25 and 0 µmol m −2 s −1 for vascular plants and 2000, 35 and 0 µmol m −2 s −1 for Sphagna. Light levels were designed to catch both the linear, light-limited beginning and the light-saturated maximum of the light response curve without causing photoinhibitory reduction of photosynthetic rate (Laine et al, 2015). Vascular plants were measured with a standard cuvette, but for Sphagna we used a moss cuvette of our own construction with internal dimensions of 3 × 2 × 1 cm (Hájek et al, 2009) with a net bottom to allow airflow above and below the sample reducing the aerodynamic resistance.…”