Litter decomposition under snow cover in a balsam fir forest

Abstract

In a subalpine balsam fir forest in Quebec, Canada, mass losses, respiration rates, and nitrogen and sulphur dynamics were measured on fir needles, birch leaves, lichens (mixed species), and small twigs decomposing under deep (> 1.5 m) winter snow for 6 months. Mass losses ranged from <6% (twigs) to 70% (lichens) and relative decomposition rates of needles and leaves were reversed from those expected at higher temperatures. Isolation of fir needles from direct contact with the snow did not affect decay rate, nor was decay accelerated by spring snowmelt. In situ respiration rates increased from about 1 mg CO2/(g∙day)) in February to 3–5 mg CO2/(g∙day)) in May, mostly because of rising temperatures. Summer respiration rates were much higher (> 6 mg CO2/(g∙day)). Nitrogen and suphur concentrations increased in all nonwoody litter over winter, but only birch leaves and some fir needles appeared to assimilate nutrients from the environment. Melting snow could easily have provided all of the nitrogen and sulphur taken up by decomposing litter. Decomposing lichens released 40 and 60%, respectively, of their initial nitrogen and sulphur contents. A literature review indicates mass losses from leaf litter decomposing under deep snow vary according to the proportion of labile material in the litter and usually constitute 40–60% of total first-year mass losses. Key words: decomposition, winter, balsam fir, snow.

Changes in foliar litter decomposition of woody plants with elevation across an alpine forest–tundra ecotone in eastern Tibet Plateau

“…Melting snow is a very likely source of N and P, and birch leaves and some fir needles could assimilate N and P from the environment (Taylor and Jones 1990). N or P content increases because microbes immobilize N and P after plant senescence in the autumn, and, thus, the released N and P are retained throughout the winter (Lipson et al 1999;Uchida et al 2005).…”

“…The litter traits of plant species are important factors that control the decomposition rate of organic matter in ecosystems (Cornelissen 1996;Cornwell et al 2008). For example, needles, hardwood leaves, grass, and forbs showed different mass loss rates, 10.0, 15.6, 21.0, and 39.0 %, respectively, under snow cover in a balsam fir (A. balsamea) forest over a 6-month snow-covered season (Taylor and Jones 1990). Moreover, the decomposition rate of different plant types is generally in the order of forbs [ graminoids [ deciduous shrubs [ evergreen shrubs (Cornelissen 1996;Cornelissen et al 2007).…”

“…The pattern of foliar litter decomposition and its related releases of carbon (C) and nutrients at high elevations and latitudes are complicated during the long, snowcovered season (Baptist et al 2010). It has been demonstrated that the first-year decomposition largely accounts for litter decomposition in subalpine forests in winter (Wu et al 2010;Zhu et al 2012), and that the role of environmental factors seems to be the most important for winter decomposition in cold biomes (Taylor and Jones 1990;Hobbie and Chapin III 1996).…”

Soil microbial and nutrient dynamics in a wet Arctic sedge meadow in late winter and early spring

“…The increase in resources probably represents the release of inorganic nutrients in free water in late winter and during spring thaw that had accumulated over winter, as a result of fragmentation of plant litter, cell lysis, leaching of nutrients from tissues and mineralization (Hobbie and Chapin, 1996). Taylor and Jones (1990) concluded that decomposition over the winter usually led to a loss of between 40% and 60% of the litter mass, based on the results from 17 studies. In addition to inorganic nutrients, pools of soluble organic C and N also rose in early April and much of this organic C and N was probably derived from the lysis of microbial necromass that had remained in a frozen state over the winter.…”

Seasonality of soil microbial nitrogen turnover in continental steppe soils of Inner Mongolia

“…Furthermore, microbial biomass and the activities of several soil enzymes were even found to peak in late winter in alpine soils (Lipson et al 1999(Lipson et al , 2002. Furthermore, significant plant litter decomposition was found in winter in seasonally snow-covered ecosystems (Taylor and Jones 1990, Hobbie and Chapin 1996, Schmidt and Lipson 2004.…”