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The development of several large‐, "continental"‐scale ecosystem research infrastructures over recent decades has provided a unique opportunity in the history of ecological science. The Global Ecosystem Research Infrastructure (GERI) is an integrated network of analogous, but independent, site‐based ecosystem research infrastructures (ERI) dedicated to better understand the function and change of indicator ecosystems across global biomes. Bringing together these ERIs, harmonizing their respective data and reducing uncertainties enables broader cross‐continental ecological research. It will also enhance the research community capabilities to address current and anticipate future global scale ecological challenges. Moreover, increasing the international capabilities of these ERIs goes beyond their original design intent, and is an unexpected added value of these large national investments. Here, we identify specific global grand challenge areas and research trends to advance the ecological frontiers across continents that can be addressed through the federation of these cross‐continental‐scale ERIs. Plain Language Summary: The development of several large‐, "continental"‐scale ecosystem research infrastructures over recent decades has provided a unique opportunity in the history of ecological science. By bringing together these research infrastructures and harmonizing their respective data will more broadly enable cross‐continental ecological research. It will also improve the capabilities of the research community to anticipate and address future global scale ecological challenges to the planet. Moreover, increasing the international capabilities of these research infrastructures goes beyond their original design intent, and is an unexpected added value of these large national investments. Here, we identify specific global grand challenge areas and research trends to advance the ecological frontiers across continents that can be addressed through the federation of these cross‐continental‐scale ecosystem research infrastructures. Key Points: For the first time in history, we are able to bring together continental‐scale Ecosystem Research Infrastructures globallyThis effort enables macrosystem ecologists to ask research questions from continent‐to‐continent in ways not available beforeThis effort provides baseline data to tackle current and future unknown ecological challenges that society will face [ABSTRACT FROM AUTHOR]

We applied a 15N dilution technique called "Integrated Total Nitrogen Input" (ITNI) to quantify annual atmospheric N input into a peatland surrounded by intensive agricultural practices over a 2-year period. Grass species and grass growth effects on atmospheric N deposition were investigated using Lolium multiflorum and Eriophorum vaginatum and different levels of added N resulting in increased biomass production. Plant biomass production was positively correlated with atmospheric N uptake (up to 102.7 mg N pot -1) when using Lolium multiflorum. In contrast, atmospheric N deposition to Eriophorum vaginatum did not show a clear dependency to produced biomass and ranged from 81.9 to 138.2 mg N pot -1. Both species revealed a relationship between atmospheric N input and total biomass N contents. Airborne N deposition varied from about 24 to 55 kg N ha -1 yr -1. Partitioning of airborne N within the monitor system differed such that most of the deposited N was found in roots of Eriophorum vaginatum while the highest share was allocated in aboveground biomass of Lolium multiflorum. Compared to other approaches determining atmospheric N deposition, ITNI showed highest airborne N input and an up to fivefold exceedance of the ecosystem-specific critical load of 5-10 kg N ha -1 yr -1. [ABSTRACT FROM AUTHOR]

Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH), at forests, grasslands, and croplands across Europe. Biogenic contributions to DIC were estimated by means of its δC signature. Leaching of biogenic DIC was 8.3±4.9 g m yr for forests, 24.1±7.2 g m yr for grasslands, and 14.6±4.8 g m yr for croplands. DOC leaching equalled 3.5±1.3 g m yr for forests, 5.3±2.0 g m yr for grasslands, and 4.1±1.3 g m yr for croplands. The average flux of total biogenic carbon across land use systems was 19.4±4.0 g C m yr. Production of DOC in topsoils was positively related to their C/N ratio and DOC retention in subsoils was inversely related to the ratio of organic carbon to iron plus aluminium (hydr)oxides. Partial pressures of CO in soil air and soil pH determined DIC concentrations and fluxes, but soil solutions were often supersaturated with DIC relative to soil air CO. Leaching losses of biogenic carbon (DOC plus biogenic DIC) from grasslands equalled 5-98% (median: 22%) of net ecosystem exchange (NEE) plus carbon inputs with fertilization minus carbon removal with harvest. Carbon leaching increased the net losses from cropland soils by 24-105% (median: 25%). For the majority of forest sites, leaching hardly affected actual net ecosystem carbon balances because of the small solubility of CO in acidic forest soil solutions and large NEE. Leaching of CH proved to be insignificant compared with other fluxes of carbon. Overall, our results show that leaching losses are particularly important for the carbon balance of agricultural systems. [ABSTRACT FROM AUTHOR]

The article presents a study conducted at the Hainich Forest in Thuringia, Germany, where uncertainty in advection and resulting carbon dioxide exchange were investigated. Approaches like the direct measurement of horizontal carbon dioxide gradient and wind speed, and the comparison of an independent value and nighttime eddy covariance were used. Another approach was the use of vertical measurements of a carbon dioxide gradient and a three-dimensional wind profile. Explanation for each approach are also presented.

Aim The aim of this study is to determine the patterns of nitrogen (N) concentrations in leaf litter of forest trees as functions of climatic factors, annual average temperature (Temp, °C) and annual precipitation (Precip, dm) and of forest type (coniferous vs. broadleaf, deciduous vs. evergreen, Pinus, etc.). Location The review was conducted using data from studies across the Eurasian continent. Methods Leaf litter N concentration was compiled from 204 sets of published data (81 sets from coniferous and 123 from broadleaf forests in Eurasia). We explored the relationships between leaf litter N concentration and Temp and Precip by means of regression analysis. Leaf litter data from N2-fixing species were excluded from the analysis. Results Over the Eurasian continent, leaf litter N concentration increased with increasing Temp and Precip within functional groups such as conifers, broadleaf, deciduous, evergreen and the genus Pinus. There were highly significant linear relationships between ln(N) and Temp and Precip ( P < 0.001) for all available data combined, as well as for coniferous trees, broadleaf trees, deciduous trees, evergreen trees and Pinus separately. With both Temp and Precip as independent variables in multiple regression equations, the adjusted coefficient of determination ( ) was evidently higher than in simple regressions with either Temp or Precip as independent variable. Standardized regression coefficients showed that Temp had a larger impact than Precip on litter N concentration for all groups except evergreens. The impact of temperature was particularly strong for Pinus. Conclusions The relationship between leaf litter N concentration and temperature and precipitation can be well described with simple or multiple linear regression equations for forests over Eurasia. In the context of global warming, these regression equations are useful for a better understanding and modelling of the effects of geographical and climatic factors on leaf litter N at a regional and continental scale. [ABSTRACT FROM AUTHOR]

Carbon fluxes were investigated in a mature deciduous forest, located in Northern Germany (53°47′N–10°36′E), by means of eddy-covariance technique, stand survey and models. This forest has been managed following a concept of nature-oriented forestry since the 1980s. One of the goals of the study was to test whether changed management led to increased carbon sequestration. The forest contains several broadleaved tree species. Depending on wind direction, the fetch-area of the eddy-covariance data was dominated by different tree species. Three subplots dominated by Oak, Beech or Alder/Ash could be distinguished from the tower data. In each of these subplots, 30× 30 m2 areas were defined to analyse leaf area index, litterfall and the increase of the wood biomass.Eddy-covariance analysis showed that the gross primary productivity (GPP′) was higher in the Oak subplot (−1794 g C m−2 yr−1) in comparison with the Beech plot and the Alder/Ash plot (−1470 and−1595 g C m−2 yr−1, respectively). The total ecosystem respiration (TER) was the highest in the Alder/Ash-dominated subplot (1401 g C m−2 yr−1) followed by the Oak plot and the Beech plot (1235 and 1174 g C m−2 yr−1, respectively). The resulting net ecosystem productivity (NEP) was−559 g C m−2 yr−1 for the Oak-dominated subplot,−295 g C m−2 yr−1 for the Beech plot and−193 g C m−2 yr−1 for the Alder/Ash plot.From Stand survey and modelling, the net primary productivity was estimated as 1103, 702 and 671 g C m−2 yr−1 in the Oak, Beech and Alder/Ash plot, respectively. Also carbon flux with litterfall was the highest in the Oak plot 343 g C m−2 yr−1 and lowest in Alder/Ash plot (197 g m−2 yr−1) with the Beech plot in between (228 g m−2 yr−1). The observations indicate an increase of the proportion of litterfall with increasing GPP′ and a different ability of carbon sequestration of the three stands in medium temporary scale. Only in the Oak stand that comprised the oldest trees and the most structured canopy the carbon sequestration was increased compared with conventionally managed forests. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the relationships between climatic factors and litterfall in coniferous and broadleaf forests in Eurasia and to explore the difference in litterfall between coniferous and broadleaf forests as related to climate at a continental scale. We have used data from across Eurasia. The relationships between litterfall and climatic factors were examined using linear regression analysis of a compilation of published data from coniferous and broadleaf forests in Eurasia. The relationships between litterfall and climatic factors show that in the temperate, subtropical, and tropical areas, broadleaf forests had higher litterfall than coniferous ones, whilst the opposite was found for boreal forests. Combining all climatic zones, a multiple regression analysis using annual mean temperature (T) and annual precipitation (P) as independent variables gave an adjusted R2 ( ) of 0.272 for total litterfall in coniferous forests ( n = 199, P < 0.001), 0.498 for broadleaf litterfall ( n = 240, P < 0.001), and 0.535 for combined coniferous and broadleaf litterfall ( n = 439, P < 0.001). The linear models for broadleaf stands have significantly higher coefficients for T and P than those for coniferous ones but the intercepts were similar. Thus, litterfall in broadleaf forests increased faster with T and P than that in coniferous forests. Further, a transformation of temperature and precipitation to relative units showed that a relative-unit change in T had a larger impact than P on total litterfall in broadleaf forests. The results indicate that at a continental scale, climatic controls over litterfall differ between coniferous and broadleaf forests. A relative unit change in annual mean temperature has a greater effect on litterfall compared to the same change in annual precipitation across the Eurasian forests. Further, the higher response to T for broadleaf forests indicates a difference in climate control between coniferous and broadleaf forests at a continental scale, and consequently different litterfall responses to climate change. [ABSTRACT FROM AUTHOR]

Reports a variation in root respiration and total soil respiration measured in an alder forest. Comparisons between measurements of total soil respiration and calculations by process models; Determination of variation by fine root structural parameters; Causes of deviations during early summer.