The increased prevalence of smaller-bodied species under warmer conditions (community downsizing) is hypothesized as an ecologically critical consequence of climate change, leading to changes in ...trophic transfer efficiency, and rates of nutrient and energy flux within ecosystems. This study used 100 intact peat-soil mescosms to measure changes in belowground biodiversity under three manipulated climate variables: elevated temperature, elevated CO2, and altered water table. Changes in species richness, abundance, community composition and body size spectra were used to determine whether climate change factors led to community downsizing, and elucidate any underlying mechanisms. Warming was the primary driver of compositional shifts in belowground fauna communities with the strongest effect among the smaller-bodied, non-sexually reproducing species. Increases in abundance driven by enhanced reproduction in small-bodied species rather than an increased extinction-rate among large-bodied predators was the basis of the observed downsizing. The overall consequences of warming-induced changes in belowground systems on ecosystem function are still unclear. However, as body size is intricately linked to metabolism, observed community downsizing suggests reductions in food web trophic transfer efficiency with consequences for nutrient and energy dynamics in belowground systems.
•This study demonstrates community downsizing in an experimental soil context.•Experimental warming lead to composition shifts in belowground fauna communities.•These shifts sare driven by enhanced reproduction in small-bodied species.•No increase in extinction-rate among large-bodied predators was observed.•Community downsizing in soil systems has important consequences for soil function.
Rare, long‐distance dispersal events are a key process in generating and maintaining patterns in biological diversity and species distributions across space and time. The 9.0 magnitude earthquake ...that struck the eastern coast of Japan in 2011, and the subsequent 38 m high tsunami washed large amounts of shoreline debris into the Pacific Ocean that led to a large‐scale biological rafting event carrying nearly 300 marine species to the western shores of North America. Whether oceanic, trans‐Pacific dispersal via rafting generates long distance dispersal events for small, flightless, terrestrial species is unknown. By sampling beach debris associated with known hot‐spots of tsunami debris along the north and east shores of Graham Island, Haida Gwaii, Canada, I document significantly dissimilar invertebrate communities associated with tide‐line beach debris and the occurrence of several putative Japanese species of soil‐dwelling mites (Acari: Oribatida). Previous explanations of Haida Gwaii's unique flora and fauna have been attributed to a proximity to the Beringian land bridge and the accumulated evidence of near‐offshore glacial refugia during the last glacial period. However, my research also suggests that stochastic, trans‐Pacific rafting events contribute to the biodiversity and biogeography of soil communities on the west coast of North America.
In the ecological literature, a ‘home-field advantage’ (HFA) describes the phenomenon where plant litters are broken down more quickly in their native versus a foreign environment due to a ...hypothesized specialised decomposer-litter relationship. Climate change is expected to spatially shift plant communities at an imbalanced rate compared to their decomposers, resulting in previously unexperienced above- and belowground pairings. Understanding decomposition dynamics has implications for global climate and carbon models, yet a clear predictive framework for the HFA has not been proposed. The ecological HFA concept is borrowed from the sports realm where extensive research has found a consistent, greater-than-random chance that teams in sports competitions win games played at their home venue because players are in better physical and psychological states. While research continues to show the sports HFA present in all types of sports independent of playing level or region, the ecological HFA has been shown inconsistently and cannot currently be generalised across scales and ecosystems. In this review, we map the ecological HFA onto a framework used to interpret the HFA in sports. First, we identify and outline the ‘game’ of decomposition, the ‘teams’ of decomposer organisms, how plants ‘coach’ this game, and also how ecological researchers are involved in their role as game ‘officials’. Second, we place parallels between the game location factors established in the sports analogy and their ecological counterparts to reveal a greater mechanistic understanding of the ecological HFA. Here we explore microbial adaptation to abiotic environments, the role of historical resource inputs, and how degree of ecosystem contrast and definitional ambiguity affect the HFA. In doing so, we discuss how microbial functional breadth, plant strategy and temporal effects play into the HFA. Using the sports HFA framework provides a novel and promising approach to understanding the ecological HFA that has been lacking, and helps identify potential factors that may not traditionally have been considered. Our framework incorporates multiple theories and views the HFA as a ‘team effort’ involving multiple components.
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•A home-field advantage (HFA) is consistently documented in sports, but not ecology.•A conceptual framework for interpreting the ecological HFA is proposed.•Location factors of home and away decomposition sites are important considerations.•Microbial functional breadth and plant strategy play a role in the HFA.•Spatio-temporal scale and plant-microbe trait trade-offs provide insight to the HFA.
A significant fraction of the Earth's land surface is dominated by bryophytes. Research on carbon and nitrogen budgets of tundra, boreal, and peatland ecosystems has demonstrated the important role ...of mosses in understanding global change. Bryophytes are also habitat to a highly diverse microbiota that plays a key role in the function of these ecosystems. Here we define the term bryosphere to emphasize the combined role of mosses and their associated organisms in the functioning of ecosystems from local to global scales. In this minireview, we emphasize the value of the bryosphere as a spatially bounded, whole ecosystem that integrates aboveground and belowground processes, and we highlight the potential of the bryosphere as a natural model system (NMS) to assist in the study of environmental change on biodiversity and ecosystem functioning. We propose a formal definition of the bryosphere, attempt to summarize the current state of knowledge of the bryosphere, and discuss how the bryosphere can be a complex yet tractable system under an NMS framework. Recent use of the bryosphere as an NMS has shown how alterations in food web structure can affect ecosystem function in a manner that, although predicted by theory, has remained largely untested by experiment. An understanding of the biodiversity, ecosystem functioning, and adaptation of the bryosphere can be advanced by manipulative experiments coupled with a blend of techniques in molecular, physiological, community, and ecosystem ecology. Although studies described herein have demonstrated the utility of the bryosphere NMS for addressing ecological theory, the bryosphere is an underutilized system with exceptional promise.
The notion that plants are tightly coupled to their belowground environment so that decomposition occurs faster in their place of origin is now a widely tested hypothesis known as the home-field ...advantage (HFA). Microbial adaptation to the most prevalent plant litter is the hypothesis proposed to explain decomposition results in a number of HFA studies but fails to corroborate results of many others, highlighting the need for a more comprehensive understanding of decomposition dynamics at local scales. Boreal peatlands are important ecosystems for carbon storage that are expected to be significantly affected by climate change, thus understanding decomposition dynamics in Boreal peatland systems is of global relevance. We performed a reciprocal transplant experiment using pure and mixed litters of two dominant peatland plant types (Sphagnum moss and Carex sedge) present in differing densities at two sites differing in nutrient status in a Boreal peatland complex. Aboveground (temperature, relative humidity) and belowground (pH, moisture, available nitrogen) environmental characteristics were measured, and initial litter quality (C, N, S) was assessed with decomposition (mass loss) quantified after one year. We use linked HFA equations that help account for differences in litter quality and site conditions. While Carex lost greater overall mass than Sphagnum, both Carex and Sphagnum demonstrate a HFA, but only where they were the dominant plant of each site. This result held for both pure and mixed litters, suggesting microbial specificity to the most prevalent plant type, yet mixed litters moderated the strength of the HFA. While our results provide novel insights to plant-soil linkages and mixed litter interactions in Boreal peatlands, mechanisms underpinning microbial specificity to plant litter in these ecosystems requires further investigation.
•Home-field advantage was observed for the dominant plant of each site.•Litter quality did not explain the home-field advantage in pure litters.•Both synergistic and antagonistic effects were observed in mixed litters.•Our results suggest local adaptation of the microbial communities to litter quality.
CONTEXT: An ecosystem service approach for land-use or conservation decisions normally uses economic or biophysical assessments for valuating nature’s services. In contrast, even though ecosystem ...services are required for human well-being, the actual use of services by differing stakeholder groups are rarely considered in typical ecosystem service assessments, especially the more intangible, cultural ecosystem services. OBJECTIVES: The aim of this research was to quantify different uses for 15 cultural and provisioning ecosystem service indicators across seven stakeholder groups in a watershed proposed with large hydroelectric dam development. METHODS: We used a large-scale survey to quantify use and frequency of use for ecosystem services. RESULTS: We demonstrate that different stakeholder groups use ecosystem services differently, both in terms of specific ecosystem service indicators, as well as for frequency of ecosystem service use. Across all stakeholder groups, specific cultural ecosystem services were consistently more important to participants when compared to provisioning ecosystem services, especially aesthetic/scenic values. CONCLUSIONS: This work is of global importance as it highlights the importance of considering cultural ecosystem services (e.g. aesthetic/scenic, sense-of-place values) along with multiple stakeholder groups to identify the trade-offs and synergies during decision-making processes for land-use or conservation initiatives.
Foliar litter is the main input of organic carbon to many soils, and thus litter decomposition processes are integral to our understanding of carbon dynamics in soil systems. Despite the short ...duration of the leaching phase of decomposition, a considerable amount of mass loss can occur providing a valuable energy source for microbes, and influencing leaf litter chemistry for subsequent microbial decomposition. At the same time, differences in plant species and their functional traits play a role in decomposition dynamics, particularly in consideration of shifting plant communities or changes in leaf chemistry under climate change. Here we investigate the short-term leaching decomposition dynamics of three boreal peatland plant species (Carex magellanica, Chamaedaphne calyculata, Sphagnum magellanicum) grown under ambient and elevated levels of atmospheric CO2. Litter chemistry was significantly different among all three plant species. In addition, plant tissues grown under elevated CO2 showed lower total C and total N than plants grown under ambient CO2. After leaching, however litter from plants grown under elevated CO2 conditions were not significantly different in total C values compared to plants grown under ambient CO2 conditions. Mass loss corresponded with the total dissolved organic carbon release across all species and was greatest in Chamaedaphne, a woody shrub; measures of carbon lability (SUVA254) were significantly greater in vascular plant species compared to Sphagnum moss. Mass loss was reduced in plants grown under elevated CO2 conditions, suggesting allocation to more non-soluble structural compounds. Placing our results within a climate change scenario where peatland plant community compositional shifts from mosses to graminoids and woody shrubs have been observed, we suggest that greater amounts of more labile carbon released from vascular plant species indicates a shift to more decomposable litters with the potential to stimulate microbial growth and activity.
•Plant species identity and CO2 growing conditions influence soluble carbon release.•Vascular plant species release more carbon of greater lability during leaching.•Elevated CO2 growing conditions increased carbon lability of vascular plants.•Plant species shift under climate change will likely impact carbon inputs to soils.
Microbial and faunal decomposers regulate the flux of carbon and nitrogen belowground, thus controlling the storage/release of carbon and nitrogen in soil systems. Warming is anticipated to alter ...decomposer biomass, and accelerate organismal metabolism and soil carbon release. We parameterized six soil food webs using empirical data for 18 trophic nodes at two boreal peatland sites under three climate scenarios (control, +2 °C, +4 °C), and model carbon and nitrogen flux, loss and retention using an energetic ecostoichiometric food web model. Differences in microbial biomass between sites dictated flux under warming. The community biomass of the fungal-dominated site was more impacted by warming, but fluxes were more responsive to warming at the bacterial-dominated site. Decreased metabolic efficiency of the soil food web at both sites in response to warming led to greater per capita carbon losses, indicating the long-term carbon storage potential of both systems is diminished.
•Six empirical soil food webs were created for two boreal peatland sites.•We modeled carbon flux under three climate scenarios.•Differences in microbial biomass between sites dictated flux under warming.•Fungal biomass was more impacted by warming but bacteria dictate flux response.•Decreased metabolic efficiency under warming diminishes carbon storage potential.
Aims
Global change is shown to significantly affect the C storage function of peatlands; however, a majority of previous research is focused on a single environmental stressor such as the increased ...temperature. As a result, little is known about the interactive effect of multiple environmental stressors on peatland C storage, especially in sedge-dominated fen peatlands.
Methods
We performed a full factorial experiment of increased temperature and elevated atmospheric CO
2
concentration on minerotrophic, sedge-dominated fen monoliths to experimentally examine the individual and interactive effects of simulated future climate conditions on peatland plant biomass, CO
2
exchange, and pore water dissolved organic carbon (DOC) over one full growing season.
Results
Our study demonstrates that warming and elevated atmospheric CO
2
significantly increased aboveground and belowground biomass, respectively, as well as the gross ecosystem production (GEP), while the DOC concentrations and respired CO
2
from peatland soils only increased under warming
Conclusions
Our results suggest that global change will increase both plant production and microbial decomposition, but with altered plant biomass allocation between aboveground and belowground. Our study provides experimental evidence for shifts in ecosystem-level carbon dynamics under global change for a sedge-dominated peatland, and suggests that while carbon stores may weaken, the carbon sink will be maintained in these types of northern peatlands if hydrological conditions are largely maintained.
In boreal peatlands, the aboveground (plant) and belowground (microbial) communities are acutely linked because the whole soil profile is partially decomposed plant matter (peat), and dictates the ...nutrients available to the belowground system. We characterized the aboveground and belowground communities in two boreal peatlands: a Sphagnum dominated fen and a Carex-dominated fen. We link the plant and microbial communities by observing plant, litter and peat carbon and nitrogen values. The Sphagnum-dominated fen had greater plant diversity but provided low quality litter inputs (high carbon:nitrogen) that formed peat and that corresponded with greater fungi:bacteria and Gram-positive:Gram-negative bacteria microbial community compared to the Carex-dominated fen. The higher quality plant inputs in the Carex-dominated fen supported a 5 × greater microbial biomass that was also 2 × more active (as measure by CO₂ production). In this approach we highlight that peatlands and their component plant and microbial communities play-out along a common resource-spectrum that dictates ‘fast’ vs ‘slow’ carbon and nutrient cycling (i.e., a plant–soil interaction spectrum) that can, in turn, affect carbon storage potential. As peatland plant community composition is predicted to shift and decomposition rates are expected to increase under climate change, our work highlights the importance of understanding plant–soil microbial interactions.
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