Effects of water level and temperature on performance of four Sphagnum mosses

Abstract

To evaluate the effects of changes in water level and temperatures on performance of four Sphagnum mosses, S. magellanicum, S. rubellum, S. imbricatum and S. fuscum were grown at two water levels, -5 cm and -15 cm, and at two temperatures, 15°C and 20°C. These species differ in their position along the microtopographical gradient and in their geographical distribution. Height increment, subcapitulum bulk density, biomass production, capitulum water content and cumulative evaporation were measured. Height increment and biomass production of S. magellanicum was lower at low water table than at high water table, whereas height increment and biomass production of S. rubellum, S. imbricatum and S. fuscum were unaffected. Height increment of S. magellanicum, S. rubellum and S. imbricatum was higher at high temperature than at low temperature. Biomass production of only S. magellanicum and S. rubellum was higher at high temperature than at low temperature, corresponding with their more southern distribution. Cumulative evaporation of S. magellanicum and S. rubellum was lower at low water table and could be explained by hampered water transport towards the capitula. We conclude that changes in water table and temperature may alter the Sphagnum composition on raised bogs, which may result in changes to important ecosystem processes. Therefore, it is important that species composition and changes therein are taken into account when evaluating global change effects on raised bog ecosystems.

Response of Sphagnum species mixtures to increased temperature and nitrogen availability

“…Other studies have shown that increased temperature can increase Sphagnum production (Asada et al 2003;Dorrepaal et al 2003;Gerdol 1995), but the temperatures used in those experiments were lower and varied between 8 and 15°C. Though Robroek et al (2007b) did find greater height increment and production at 20°C than at 15°C for several Sphagnum species, their experiment lasted for only 6 months. Harley et al (1989) and Skre and Oechel (1981) showed that photosynthesis in Sphagnum increases with temperature up to an optimum around 20-25°C.…”

“…The composition of the vegetation also determines the characteristics of a peat bog. We have already found different responses in biomass production among species when temperature is increased (Breeuwer et al 2008a;Robroek et al 2007b). It seems likely that when a species with high production and/or a low decomposition rate increases its relative abundance in a bog, this will increase the carbon storage capacity of the system.…”

The Impact of Experimental Temperature and Water Level Manipulation on Carbon Dioxide Release in a Poor Fen in Northern Poland

“…The higher temperatures elevate CO 2 respiration and may also stimulate plant productivity, especially in cold regions (Rustad et al 2001). Results of field experiments show the increased Sphagnum productivity with warming (Robroek et al 2007), as long as there was sufficient water (Dorrepaal et al 2003). In Linje mire, the noticeably lower Q10 values found in the dry treatment can be explained by changes in microclimate conditions that affect the microbial community (Luo et al 2001;Allison et al 2010;Crowther and Bradford 2013) and particularly by the lower peat moisture (Silvola et al 1996;Suseela et al 2012).…”

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

“…Mean annual temperature together with PPFD during the growing season are the most important factors explaining Sphagnum productivity on the global scale (Gunnarsson, 2005;Loisel et al, 2012), and the temperature optimum of Sphagnum photosynthesis is known to change over the growing season (Gaberščik and Martinčič, 1987). However, the temperature dependence and acclimatization of species-level photosynthesis in peatlands has been studied only with a few Sphagnum species (Gaberščik and Martinčič, 1987;Robroek et al, 2007).…”