Substrate‐derived CO₂ is important in the development of Sphagnum spp.

Abstract

Summary• The effects of different CO 2 concentrations in the acrotelm pore water on the development of Sphagnum magellanicum monoliths grown in wet conditions in the laboratory are reported here.• Decomposition processes result in much higher CO 2 concentrations in bog acrotelms than atmospheric concentrations. We therefore hypothesized that this substrate-derived carbon provides an important carbon source for Sphagnum .• S. ma gellanicum hummocks developed only when CO 2 concentrations in the acrotelm water were high. Plants in the low CO 2 treatment appeared to be carbonlimited; they had increased nutrient concentrations and decreased ratios of carbon to other nutrients. Chlorophyll concentrations were much higher in these plants, probably allowing them to harvest more CO 2 , but the allocation of carbon to structural tissues was lower, resulting in weak stems that were unable to remain upright. As a result of carbon-limitation, net biomass and height increases of the monoliths were much lower in the low CO 2 treatment.• Results indicate that, at least in wet conditions, atmospheric CO 2 alone is not sufficient to enable S. magellanicum to develop its normal vertical growth pattern. We conclude that the role of substrate-derived CO 2 as a carbon source for Sphagna is underestimated and requires reconsideration.

Buoyancy-driven flow in a peat moss layer as a mechanism for solute transport

“…The buoyancy flow described here operates at the much smaller scale of a water-saturated acrotelm, but there it may play an important role. Besides nutrients and oxygen, also dissolved organic compounds and CO 2 formed by aerobic decay and methane oxidation (13)(14)(15) will be carried by the water.…”

Moss Responses to Elevated CO2 and Variation in Hydrology in a Temperate Lowland Peatland

“…Hydrology may therefore confound elevated CO 2 responses of moss growth and abundance, although hydrology may also be influenced by elevated CO 2 effects itself through enhanced water use efficiency or cover of vascular plants (Field et al 1995;Heijmans et al 2001). Besides, moss growth in wet conditions may not only depend on atmospheric CO 2 but also on CO 2 originating from the substrate, since dissolved CO 2 concentrations in the upper peat layers are usually higher than atmospheric concentrations, reducing potential elevated atmospheric CO 2 responses of mosses (Lansdown et al 1992;Lamers et al 1999;Hornibrook et al 2000;Smolders et al 2001).…”

Radiocarbon dating of bulk peat samples from raised bogs: non-existence of a previously reported ‘reservoir effect’?

“…The core reported in the present paper consisted of a hummock (relatively dry conditions) during the investigated period. It would be interesting to repeat the present study using a core that had accumulated during lawn or hollow conditions, even more because mosses growing in hollows could contain a portion of recycled CO 2 from deeper peat layers (Price et al, 1997;Smolders et al, 2001). …”