Moss litter decomposes more slowly than vascular litter. Fact?

1. Moss litter decomposes more slowly than vascular litter. Fact?

2. * Numbers in parentheses are percent mass loss during field litter bag incubations, typically over 3 years.

3. Why does moss litter decompose slowly? 1) low N concentrations, particularly given the high nutrient use efficiency and abundance of dead hyaline cells of Sphagnum species 2) soluble phenolic compounds typically produced by some bryophytes (Rasmussen 1994) 3) insoluble phenolics (Wilson et al. 1989; Verhoeven & Liefveld 1997; Williams et al. 1998) that can mask cellulose and make tissue more recalcitrant 4) antimicrobial properties (Basile et al. 1999; Banderjee & Sen 1979)

4. But decomposition rates vary among moss species Turetsky et al., J. Ecology in press

6. Turetsky et al., J. Ecology in press

7. Mosses regulate energy balance in forests and peatlands Fact?

8. Boreal bog, Alberta Moss typically has high porosity and high water holding capacity, resulting in high heat capacity and low thermal diffusivity. Thus, loss of moss generally will serve to reduce the thermal regulation of the peat substrate.

9. Pendulous (limp) lateral branches act like a wick to soak water upwards; Horizontal lateral branches provide support via entanglement with adjacent branches from other stems.

10. Hyaline cells

11. Moss species control water holding capacity Kellner, unpubl data

12. Moss species control water holding capacity

13. Species and microtopography contribute to spatial variability in moss VMC VMC(%)

14. Decomposition history controls water holding capacity tension (10^n cm of water) VMC

15. Mosses regulate carbon and water fluxes under drought stress Sphagnum rubellum bleaching

16. Vegetation re-establishment Surface roughness length Surface roughness length IMPLICATIONS: Vegetation (moss + vasculars) regrowth alters surface characteristics and causes “changing turbulence regimes” Mulch cover Surface friction velocity Petrone et al. 2004