Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes (original) (raw)
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Ecology, 2014
Climate warming in arctic tundra may shift dominant vegetation from graminoids to deciduous shrubs, whose functional traits could, in turn, alter biotic and abiotic controls over biogeochemical cycling of carbon (C) and nitrogen (N). We investigated whether shrub-induced changes in microclimate have stronger effects on litter decomposition and nutrient release than changes in litter quality and quantity. In arctic tundra near Toolik Lake, Alaska, USA, we incubated a common substrate in a snow-addition experiment to test whether snow accumulation around arctic deciduous shrubs altered the environment enough to increase litter decomposition rates. We compared the influence of litter quality on the rate of litter and N loss by decomposing litter from four different plant functional types in a common site. We used aboveground net primary production values and estimated decay constant (k) values from our decomposition experiments to calculate community-weighted mass loss for each site. Snow addition had no effect on decomposition of the common substrate, and the site with the highest abundance of shrubs had the lowest decomposition rates. Species varied in their decomposition rates, with species from the same functional type not always following similar patterns. Community-weighted mass loss was 1.5 times greater in the high shrub site, and only slightly decreased when adjusted for soil environment, suggesting that litter quality and quantity are the primary drivers of community decomposition. Our findings suggest that on a short time scale, the changes in soil environment associated with snow trapping by shrubs are unlikely to influence litter nutrient turnover enough to drive positive snow-shrub feedbacks. The mechanisms driving shrub expansion are more likely to do with shrub-litter feedbacks, where the higher growth rates and N uptake by shrubs allows them to produce more leaves, resulting in a larger litter N pool and faster internal cycling of nutrients.
Ecosystems, 2015
The Arctic climate is projected to change during the coming century, with expected higher air temperatures and increased winter snowfall. These climatic changes might alter litter decomposition rates, which in turn could affect carbon (C) and nitrogen (N) cycling rates in tundra ecosystems. However, little is known of seasonal climate change effects on plant litter decomposition rates and N dynamics, hampering predictions of future arctic vegetation composition and the tundra C balance. We tested the effects of snow addition (snow fences), warming (open top chambers), and shrub removal (clipping), using a full-factorial experiment, on mass loss and N dynamics of two shrub tissue types with contrasting quality: deciduous shrub leaf litter (Salix glauca) and
Science of the Total Environment, 2020
Aims Litter decomposition is an important driver of soil carbon and nutrient cycling in nutrient-limited Arctic ecosystems. However, climate change is expected to induce changes that directly or indirectly affect decomposition. We examined the direct effects of long-term warming relative to differences in soil abiotic properties associated with vegetation type on litter decomposition across six subarctic vegetation types. Methods In six vegetation types, rooibos and green tea bags were buried for 70–75 days at 8 cm depth inside warmed (by open-top chambers) and control plots that had been in place for 20–25 years. Standardized initial decomposition rate and stabilization of the labile material fraction of tea (into less decomposable material) were calculated from tea mass losses. Soil moisture and temperature were measured bi-weekly during summer and plant-available nutrients were measured with resin probes. Results Initial decomposition rate was decreased by the warming treatment. Stabilization was less affected by warming and determined by vegetation type and soil moisture. Soil metal concentrations impeded both initial decomposition rate and stabilization. Conclusions While a warmer Arctic climate will likely have direct effects on initial litter decomposition rates in tundra, stabilization of organic matter was more affected by vegetation type and soil parameters and less prone to be affected by direct effects of warming.
Oecologia, 2012
Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the eVects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year Weld experiment, we manipulated these seasonal components in a sub-arctic bog and studied the eVects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis < Betula < Rubus. After 4 years, overall mass loss in the climate-treatment plots was 10 % higher compared to the ambient incubation environment. Litter chemistry showed within each incubation environment only a few and species-speciWc responses. Compared to the interspeciWc diVerences, they resulted in only moderate climate treatment eVects on mass loss and these diVered among seasons and species. Neither N nor P mineralization in the litter were aVected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species diVered in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited eVects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.
Ecology, 2017
Rapid arctic vegetation change as a result of global warming includes an increase in the cover and biomass of deciduous shrubs. Increases in shrub abundance will result in a proportional increase of shrub litter in the litter community, potentially affecting carbon turnover rates in arctic ecosystems. We investigated the effects of leaf and root litter of a deciduous shrub, Betula nana, on decomposition, by examining species-specific decomposition patterns, as well as effects of Betula litter on the decomposition of other species. We conducted a 2-yr decomposition experiment in moist acidic tundra in northern Alaska, where we decomposed three tundra species (Vaccinium vitis-idaea, Rhododendron palustre, and Eriophorum vaginatum) alone and in combination with Betula litter. Decomposition patterns for leaf and root litter were determined using three different measures of decomposition (mass loss, respiration, extracellular enzyme activity). We report faster decomposition of Betula lea...
Plant and Soil, 2013
Aims Climate-induced changes in snow cover are likely to affect cold arctic and alpine ecosystems functioning and major processes such as wintertime plant litter decomposition. However, it remains poorly studied in subalpine systems where the snowpack may be irregular. In this paper we explored the dynamic of the winter plant litter decomposition process, its magnitude and its relationship with the snowpack properties. Methods In subalpine grasslands of the Central French Alps, we performed a litter bag experiment monitoring over a whole winter the litter decomposition from the exploitative Dactylis glomerata and the conservative Festuca paniculata, under two contiguous experimental sites with snowpacks differing in depth and physical properties. Results Litter decomposition rates were stable during winter and 3-fold higher under deeper and permanent snowpack with higher thermal resistance. Litter quality appeared only significant under thinner snowpack with higher decomposition rates for the exploitative species. A snowpack with higher thermal resistance created an insulating layer promoting the decomposition process. Conclusion These results suggest that the temporal (permanence vs. intermittency) and physical (depth Plant Soil (2013) 363:215-229
Vegetation exerts a greater control on litter decomposition than climate warming in peatlands
Ecology, 2014
Understanding the effects of warming on greenhouse gas feedbacks to climate change represents a major global challenge. Most research has focused on direct effects of warming, without considering how concurrent changes in plant communities may alter such effects. Here, we combined vegetation manipulations with warming to investigate their interactive effects on greenhouse gas emissions from peatland. We found that although warming consistently increased respiration, the effect on net ecosystem CO 2 exchange depended on vegetation composition. The greatest increase in CO 2 sink strength after warming was when shrubs were present, and the greatest decrease when graminoids were present. CH 4 was more strongly controlled by vegetation composition than by warming, with largest emissions from graminoid communities. Our results show that plant community composition is a significant modulator of greenhouse gas emissions and their response to warming, and suggest that vegetation change could alter peatland carbon sink strength under future climate change.
Control of Litter Decomposition in a Subalpine Meadow–Sagebrush Steppe Ecotone Under Climate Change
Ecological Applications, 2001
Litter decomposition is an important component of the global carbon and nitrogen cycles. Because climate exerts strong controls over rates of litter decomposition, climate change may alter both cycles. Climate change can influence litter decomposition rates directly, or indirectly through changes in litter quality. The relative importance of climate and litter quality in controlling rates of decomposition varies across ecosystem types. Thus, ecosystem responses to climate change are not readily predictable. This study examines in situ litter decomposition rates of native plant litter of different growth forms (grass, forb, and shrub) in two microclimates (xeric and mesic). In a Colorado subalpine meadow-sagebrush steppe ecotone, a climate-warming treatment was used to determine the influence of litter quality, microclimate, and warming on the rates of decomposition. Three one-year litter bag experiments were performed using senescent leaf litter of the three growth forms from a xeric microclimate (shrub, Artemisia tridentata; grass, Festuca thurberi; forbs, Delphinium nuttallianum, Erigeron speciosus) and a mesic microclimate (shrub, Pentaphylloides floribunda; grass, Festuca thurberi; forbs, Erythronium grandiflorum, Ligusticum porteri). A reciprocal transplant litter experiment was performed in the third year to determine the direct effect of warming on litter quality and subsequent litter mass loss rates. Evidence suggests that decomposition was limited by moisture in the xeric zone and by temperature in the mesic zone. Decomposition rates were strongly correlated with the initial lignin:N ratio of the litter. The forbs had a much lower initial lignin:N ratio and, therefore, decomposed at a much higher rate than did the grasses or shrubs. In a changing climate, initial microclimate and changes in litter quality of the bulk litter produced as a result of shifts in species composition may be more important in determining rates of litter decomposition than the direct effect of warming.
Litter decomposition in two subalpine forests during the freeze–thaw season
Acta Oecologica, 2010
Mass loss and nutrient release of forest litter during the freezeethaw season could play an essential role in C and nutrient cycling in cold regions, but few studies in some key ecosystems have been available. In order to characterize litter decomposition during the freezeethaw season in a subalpine forest region of western China, a field experiment using the litterbag method was conducted on the decomposition of foliar litter of two dominant species, fir (Abies faxoniana) and birch (Betula platyphylla) under their respective forests. Over the freezeethaw season following leaf-fall, about 18% and 20% of mass, 13% and 14% of lignin, 30% and 26% of cellulose, 14% and 21% of C, 30% and 27% of N, 17% and 15% of P, and 17% and 13% of K were lost from fir and birch litters, respectively. The lost mass and components accounted for more than 64% and 65% of mass, 72% and 69% of lignin, 75% and 60% of cellulose, 49% and 59% of C, 56% and 71% of N, 62% and 37% of P, and 38% and 37% of K in 1 year net loss rate of fir and birch litter, respectively. In addition, the loss of mass, lignin, cellulose and component bio-elements during the freezeethaw season correlated closely with the initial substrate type and the levels of the individual bioelements. The results demonstrated that litter decomposition during the freezeethaw season contributes significantly to the first year decomposition in these subalpine forests.