Vegetation exerts a greater control on litter decomposition than climate warming in peatlands

Abstract

Abstract. Historically, slow decomposition rates have resulted in the accumulation of large amounts of carbon in northern peatlands. Both climate warming and vegetation change can alter rates of decomposition, and hence affect rates of atmospheric CO 2 exchange, with consequences for climate change feedbacks. Although warming and vegetation change are happening concurrently, little is known about their relative and interactive effects on decomposition processes. To test the effects of warming and vegetation change on decomposition rates, we placed litter of three dominant species (Calluna vulgaris, Eriophorum vaginatum, Hypnum jutlandicum) into a peatland field experiment that combined warming with plant functional group removals, and measured mass loss over two years. To identify potential mechanisms behind effects, we also measured nutrient cycling and soil biota. We found that plant functional group removals exerted a stronger control over short-term litter decomposition than did ;18C warming, and that the plant removal effect depended on litter species identity. Specifically, rates of litter decomposition were faster when shrubs were removed from the plant community, and these effects were strongest for graminoid and bryophyte litter. Plant functional group removals also had strong effects on soil biota and nutrient cycling associated with decomposition, whereby shrub removal had cascading effects on soil fungal community composition, increased enchytraeid abundance, and increased rates of N mineralization. Our findings demonstrate that, in addition to litter quality, changes in vegetation composition play a significant role in regulating short-term litter decomposition and belowground communities in peatland, and that these impacts can be greater than moderate warming effects. Our findings, albeit from a relatively short-term study, highlight the need to consider both vegetation change and its impacts below ground alongside climatic effects when predicting future decomposition rates and carbon storage in peatlands.

Effects of land use and precipitation on above- and below-ground litter decomposition in a semi-arid temperate steppe in Inner Mongolia, China

“…In the present study, above-ground litter production, quality, and decomposition rates differed among the three land use types. The vegetation composition plays a significant role in regulating short-term litter decomposition and below-ground microbial communities by altering the quality and quantity of the litter that is added to the soil (Ward et al, 2015). Litter production provided an energy resource for soil microbial metabolism, and the accumulation of litter could promote litter decomposition by improving soil characteristics such as the soil water content and the characteristics of the decomposer community (Mincheva et al, 2014).…”

“…At regional to global scales, climate change can control decomposition rates by altering organic matter decomposition in the soil, but also by altering the quantity and quality of inputs of plant litter (Ward et al, 2015). Thus, the combination of climate change and land-use change will affect litter decomposition in temperate grasslands, possibly in synergistic ways (Benot et al, 2014).…”

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

“…However, the relative importance of temperature and hydrological conditions for R ECO is unclear and seems to depend on their relative effect on autotrophic and heterotrophic pathways, which might be decoupled (Lafleur et al 2005). Remarkably, the effect of vegetation on heterotrophic respiration seems to be larger than the effect of temperature (Ward et al 2015) or water table (Turetsky et al 2008), highlighting the importance of these biotic controls on peatland carbon fluxes.…”

Effects of Different Land Use on Soil Bacterial Functional Diversity in Sanjiang Plain, Northeast China

“…ETLaNDS, which account for 5~8% of the earth's surface, offer a high degree of biodiversity, and have important ecological functions such as water purification and flood control [1][2][3]. Moreover, wetland ecosystems play key roles in regulating global greenhouse gases and carbon sinks.…”