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Ecosystems 

Latest Results for Ecosystems
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Disproportionate Contribution of Vegetated Habitats to the CH4 and CO2 Budgets of a Boreal Lake
17. Januar 2022
Abstract Many lakes have areas that are colonized by different types of macrophytes, including emergent plants that are rooted in sediments. Emergent macrophytes are known to influence local organic carbon (C) and greenhouse gas dynamics but are rarely considered in lake C assessments. Here, we assessed the direct and indirect effects of emergent macrophytes Typha latifolia and Brasenia schreberi on both CH4 and CO2 ambient concentrations and fluxes (diffusive, ebullitive, and plant-mediated) in a typical oligotrophic boreal lake and quantified the contribution of these...
Effects of Habitat-Specific Primary Production on Fish Size, Biomass, and Production in Northern Oligotrophic Lakes
12. Januar 2022
Abstract Ecological theory predicts that the relative distribution of primary production across habitats influence fish size structure and biomass production. In this study, we assessed individual, population, and community-level consequences for brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) of variation in estimated habitat specific (benthic and pelagic) and total whole lake (GPPwhole) gross primary production in 27 northern oligotrophic lakes. We found that higher contribution of benthic primary production to GPPwhole was associated with higher...
Seasonal Mass Migration of Water Boatmen (Hemiptera: Corixidae) as a Wetland–River Linkage and Dietary Subsidy to Riverine Fish
10. Januar 2022
Abstract Cross-boundary movements of organisms can act as important ecosystem linkages by subsidizing food webs. We investigated the magnitude and implications of a little understood food web subsidy in the form of migrating aquatic insects, corixids (Hemiptera: Corixidae), that fly from geographically isolated wetlands into large rivers in the Prairie Pothole Region (PPR) of North America every fall, to overwinter. We found that these migrations can lead to drastically increased riverine corixid densities as high as ~ 3,000 individuals/m2 within areas of standing or...
Increased Water Use Efficiency in China and Its Drivers During 2000–2016
08. Januar 2022
Abstract Water use efficiency (WUE), the carbon uptake per unit of water consumption, is a critical indicator of the coupling between water and carbon cycles in terrestrial ecosystems. Understanding the spatiotemporal changes in WUE and its drivers is vital for predicting ecosystem responses to environmental changes. Herein, we used a remote sensing-driven analytical model to estimate spatiotemporal variations of WUE in China during 2000–2016 and quantified its key drivers. The simulated WUE matched well with the eddy covariance observations across different ecosystems...
Combining Techniques to Conceptualise Denitrification Hot Spots and Hot Moments in Estuaries
07. Januar 2022
Abstract Degradation of aquatic ecosystems from nutrient pollution is a global issue, and quantifying nutrient removal in coastal ecosystems is a topic of interest for coastal managers worldwide. Analysing relationships between natural nitrogen removal processes, such as denitrification, and environmental variables from an ecological (rather than biogeochemical) perspective may help to identify and predict biogeochemically important habitat patches (hot spots). However, in situ measurements of denitrification that are coupled with ecosystem variables are rare. In this...
Biophysical Determinants of Shifting Tundra Vegetation Productivity in the Beaufort Delta Region of Canada
01. Januar 2022
Abstract Temperature increases across the circumpolar north have driven rapid increases in vegetation productivity, often described as ‘greening’. These changes have been widespread, but spatial variation in their pattern and magnitude suggests that biophysical factors also influence the response of tundra vegetation to climate warming. In this study, we used field sampling of soils and vegetation and random forests modeling to identify the determinants of trends in Landsat-derived Enhanced Vegetation Index, a surrogate for productivity, in the Beaufort Delta region...
Bryosphere Loss Impairs Litter Decomposition Consistently Across Moss Species, Litter Types, and Micro-Arthropod Abundance
20. Dezember 2021
Abstract The bryosphere (that is, ground mosses and their associated biota) is a key driver of nutrient and carbon dynamics in many terrestrial ecosystems, in part because it regulates litter decomposition. However, we have a poor understanding of how litter decomposition responds to changes in the bryosphere, including changes in bryosphere cover, moss species, and bryosphere-associated biota. Specifically, the contribution of micro-arthropods to litter decomposition in the bryosphere is unclear. Here, we used a 16-month litterbag field experiment in two boreal forests...
Tree Diversity, Initial Litter Quality, and Site Conditions Drive Early-Stage Fine-Root Decomposition in European Forests
20. Dezember 2021
Abstract Decomposition of dead fine roots contributes significantly to nutrient cycling and soil organic matter stabilization. Most knowledge of tree fine-root decomposition stems from studies in monospecific stands or single-species litter, although most forests are mixed. Therefore, we assessed how tree species mixing affects fine-root litter mass loss and which role initial litter quality and environmental factors play. For this purpose, we determined fine-root decomposition of 13 common tree species in four European forest types ranging from boreal to Mediterranean...
Recent Lateral Expansion of Sphagnum Bogs Over Central Fen Areas of Boreal Aapa Mire Complexes
20. Dezember 2021
Abstract We investigated recent changes in spatial patterning of fen and bog zones in five boreal aapa mire complexes (mixed peatlands with patterned fen and bog parts) in a multiproxy study. Comparison of old (1940–1970s) and new aerial images revealed decrease of flarks (wet hollows) in patterned fens by 33–63% in middle boreal and 16–42% in northern boreal sites, as lawns of bog Sphagnum mosses expanded over fens. Peat core transects across transformed areas were used to verify the remote sensing inference with stratigraphic analyses of macrofossils...
Is Oxygenation Related to the Decomposition of Organic Matter in Cryoconite Holes?
17. Dezember 2021
Abstract Cryoconite is a sediment occurring on glacier surfaces worldwide which reduces ice albedo and concentrates glacier surface meltwater into small reservoirs called cryoconite holes. It consists of mineral and biogenic matter, including active microorganisms. This study presents an experimental insight into the influence of sediment oxygenation on the cryoconite ability to produce and decomposition of organic matter. Samples were collected from five glaciers in the Arctic and the European mainland. Cryoconite from three glaciers was incubated in stagnant and...
Stream Water Chemistry in Mixed-Conifer Headwater Basins: Role of Water Sources, Seasonality, Watershed Characteristics, and Disturbances
01. Dezember 2021
Abstract Understanding the transport of dissolved organic carbon (DOC) and nitrogen (N) as water flows through headwater basins is important for predicting downstream water quality. With increased recognition of climatic impact on nutrient transport, more studies are needed in headwater basins experiencing a Mediterranean-type climate, such as those of the Sierra Nevada, California. We analyzed water samples collected over 5 years from eight low-order and mixed-conifer watersheds to elucidate the temporal variation of water chemistry and evaluate their responses to...
Decomposition in Mixed Beech Forests in the South-Western Alps Under Severe Summer Drought
01. Dezember 2021
Abstract Climate and plant litter diversity are major determinants of carbon (C) and nitrogen (N) cycling rates during decomposition. Yet, how these processes will be modified with combined changes in climate and biodiversity is poorly understood. With a multisite field experiment, we studied the interactive effects of reinforced and prolonged summer drought (using rainout shelters) and tree species mixing on leaf litter decomposition in beech forests in the French Alps. Forests included monospecific stands of Fagus sylvatica, Abies alba and Quercus pubescens and...
Soil Organic Carbon Content Decreases in Both Surface and Subsoil Mineral Horizons by Simulated Future Increases in Labile Carbon Inputs in a Temperate Coniferous Forest
01. Dezember 2021
Abstract Soils represent important pools of soil organic carbon (SOC) that can be greatly influenced by labile C inputs, which are expected to increase in future due to CO2 enrichment of atmosphere and a concomitant rise in plant primary productivity. Studying effects of variable labile C inputs on SOC pool helps to understand how soils respond to global change. However, this knowledge is missing for coniferous forest soils despite being widespread throughout the northern temperate zone. We conducted a 7-month field manipulation experiment to study the effects of...
Post-Glacial Climate–Fire Interactions Control Tree Composition of Mesic Temperate Forests in Eastern North America
01. Dezember 2021
Abstract Stand-scale gap-phase dynamics is generally viewed as the main driver of development in mesic deciduous forests of the temperate biome. Soil charcoal of temperate forests in eastern North America are unnoticed in most surveys, thus explaining why fire is undervalued as a driver of forest succession. The extent to which gap-phase, fire, or other processes are responsible for the regeneration and maintenance of mesic deciduous forests is unknown because paleoecological evidence is lacking. We tested the fire-driven succession hypothesis on the development of this...
Legacies of Nutrient Accumulation and Depletion in Residential Ecosystems
01. Dezember 2021
Abstract In residential ecosystems, land management can help regulate climate and improve water quality by promoting the accumulation of nutrients in the soil. We tested how varying intensity of residential land use and management altered nutrient (Ca, K, Mg, P, S) pools. We studied soils and vegetation across twelve land use-intensity gradients (yards-perennial old fields-forests) established 15–227 y. ago in the native ecosystems of temperate forests. We found that yard soils were enriched with nutrients relative to fields and forests, regardless of recent yard...
Coupled Shifts in Ectomycorrhizal Communities and Plant Uptake of Organic Nitrogen Along a Soil Gradient: An Isotopic Perspective
01. Dezember 2021
Abstract Plants associating with mutualistic ectomycorrhizal (ECM) fungi may directly obtain nitrogen (N) bound in soil organic matter (N-SOM). However, the contribution of N-SOM to plant growth under field conditions remains poorly constrained. We tested the hypothesis that turnover in ECM communities along soil inorganic N gradients mediates a functional transition from plant reliance on N-SOM in low inorganic N soils, to primarily inorganic N uptake in inorganic N-rich condition soils. We quantified the δ 15 N of Q. rubra foliage and roots, organic and...
Methane and Carbon Dioxide Flux Heterogeneity Mediated by Termite Mounds in Moist Tropical Forest Soils of Himalayan Foothills, India
01. Dezember 2021
Abstract Termites are dominant soil macro-fauna in tropical forests, yet remain an uncertain component of the carbon budget in many regions. We investigated CH4 and CO2 flux patterns from termite mounds and background soils of moist tropical deciduous forests in Indian lower Himalaya from April 2015 till March 2016 using static closed chamber technique. The relation between gas fluxes and soil moisture as well as temperature were examined. Termite (Odontotermes obesus) mounds were significant localized source of CH4 (0.38 ± 0.01 mg m−2 h−1) and CO2...
Trade-offs Between Light and Nutrient Availability Across Gradients of Dissolved Organic Carbon Lead to Spatially and Temporally Variable Responses of Lake Phytoplankton Biomass to Browning
01. Dezember 2021
Abstract Northern lakes are experiencing widespread increases in dissolved organic carbon (DOC) that are likely to lead to changes in pelagic phytoplankton biomass. Pelagic phytoplankton biomass responds to trade-offs between light and nutrient availability. However, the influence of DOC light absorbing properties and carbon–nutrient stoichiometry on phytoplankton biomass across seasonal or spatial gradients has not been assessed. Here, we analyzed data from almost 5000 lakes to examine how the carbon–phytoplankton biomass relationship is influenced by seasonal...
Stream Macroinvertebrates and Carbon Cycling in Tangled Food Webs
01. Dezember 2021
Abstract The annual global loss of organic carbon from terrestrial ecosystems into rivers is similar to the organic carbon stored in soils each year. Dissolved organic matter (DOM) flows through the food web to macroinvertebrates, but little is known about the effect of DOM increase on stream food webs and how much macroinvertebrates may contribute to the regulation of carbon fluxes in rivers. Using a before and after control impact (BACI) experimental design, we increased by 12% (+ 0.52 mg C L−1) the concentration of DOM in a stream for three weeks by adding...
Differential Resilience of Soil Microbes and Ecosystem Functions Following Cessation of Long-Term Fertilization
01. Dezember 2021
Abstract Nitrogen (N) from anthropogenic sources has dramatically increased in terrestrial ecosystems globally. Although belowground microbial processes and events that release N into the atmosphere, such as fire, could support ecosystem resilience to eutrophication, little is known about how these factors might affect N loss following chronic fertilization, thus promoting ecosystem recovery. We studied how N pools, N-cycling potential rates and their affiliated microbial populations, and microbial community composition responded to the factorial effects of cessation of...