The uncertain climate footprint of wetlands under human pressure

Significant climate risks are associated with a positive carbon–temperature feedback in northern latitude carbon-rich ecosystems,making an accurate analysis of human impacts on the net greenhouse gas balance of wetlands a priority. Here, we provide a coherent assessment of the climate footprint of a network of wetland sites based on simultaneous and quasi-continuous ecosystem observations of CO2 and CH4 fluxes. Experimental areas are located both in natural and in managed wetlands and cover a wide range of climatic regions, ecosystem types, and management practices. Based on direct observations we predict that sustained CH4 emissions in natural ecosystems are in the long term (i.e., several centuries) typically offset by CO2 uptake, although with large spatiotemporal variability. Using a space-for-time analogy across ecological and climatic gradients, we represent the chronosequence from natural to managed conditions to quantify the “cost” of CH4 emissions for the benefit of net carbon sequestration. With a sustained pulse– response radiative forcing model, we found a significant increase in atmospheric forcing due to land management, in particular for wetland converted to cropland. Our results quantify the role of human activities on the climate footprint of northern wetlands and call for development of active mitigation strategies for managed wetlands and new guidelines of the Intergovernmental Panel on Climate Change (IPCC) accounting for both sustained CH4 emissions and cumulative CO2 exchange

Variability of annual CO2 exchange from Dutch grasslands

An intercomparison is made of the Net Ecosystem Exchange of CO2, NEE, for eight Dutch grassland sites: four natural grasslands, two production grasslands and two meteorological stations within a rotational grassland region. At all sites the NEE was determined during at least 10 months per site, using the eddy-covariance (EC) technique, but in different years. The NEE does not include any import or export other than CO2. The photosynthesis-light response analysis technique is used along with the respiration-temperature response technique to partition NEE into Gross Primary Production (GPP) and Ecosystem Respiration (Re) and to obtain the eco-physiological characteristics of the sites at the field scale. Annual sums of NEE, GPP and Re are then estimated using the fitted response curves with observed radiation and air temperature from a meteorological site in the centre of The Netherlands as drivers. These calculations are carried out for four years (2002–2005). Land use and management histories are not considered. The estimated annual Re for all individual sites is more or less constant per site and the average for all sites amounts to 1390±30 gC m−2 a−1. The narrow uncertainty band (±2%) reflects the small differences in the mean annual air temperature. The mean annual GPP was estimated to be 1325 g C m−2 a−1, and displays a much higher standard deviation, of ±110 gC m−2 a−1 (8%), which reflects the relatively large variation in annual solar radiation. The mean annual NEE amounts to –65±85 gC m−2 a−1. From two sites, four-year records of CO2 flux were available and analyzed (2002–2005). Using the weather record of 2005 with optimizations from the other years, the standard deviation of annual GPP was estimated to be 171–206 gC m−2 a−1 (8–14%), of annual Re 227–247 gC m−2 a−1 (14–16%) and of annual NEE 176–276 gC m−2 a−1. The inter-site standard deviation was higher for GPP and Re, 534 gC m−2 a−1 (37.3%) and 486 gC m−2 a−1 (34.8%), respectively. However, the inter-site standard deviation of NEE was similar to the interannual one, amounting to 207 gC m−2 a−1. Large differences occur due to soil type. The grasslands on organic (peat) soils show a mean net release of CO2 of 220±90 g C m−2 a−1 while the grasslands on mineral (clay and sand) soils show a mean net uptake of CO2 of 90±90 g C m−2 a−1. If a weighing with the fraction of grassland on organic (20%) and mineral soils (80%) is applied, an average NEE of 28 ±90 g C m−2 a−1 is found. The results from the analysis illustrate the need for regionally specific and spatially explicit CO2 emission estimates from grassland.An intercomparison is made of the Net Ecosystem Exchange of CO2, NEE, for eight Dutch grassland sites: four natural grasslands, two production grasslands and two meteorological stations within a rotational grassland region. At all sites the NEE was determined during at least 10 months per site, using the eddy-covariance (EC) technique, but in different years. The NEE does not include any import or export other than CO2. The photosynthesis-light response analysis technique is used along with the respiration-temperature response technique to partition NEE into Gross Primary Production (GPP) and Ecosystem Respiration (R-e) and to obtain the eco-physiological characteristics of the sites at the field scale. Annual sums of NEE, GPPand R-e are then estimated using the fitted response curves with observed radiation and air temperature from a meteorological site in the centre of The Netherlands as drivers. These calculations are carried out for four years (2002-2005). Land use and management histories are not considered. The estimated annual R-e for all individual sites is more or less constant per site and the average for all sites amounts to 1390 +/- 30 gC m(-2) a(-1). The narrow uncertainty band (+/- 2%) reflects the small differences in the mean annual air temperature. The mean annual GPP was estimated to be 1325 g C m(-2) a(-1), and displays a much higher standard deviation, of +/- 110 gC m(-2) a(-1) (8%), which reflects the relatively large variation in annual solar radiation. The mean annual NEE amounts to -65 +/- 85 gC m(-2) a(-1). From two sites, four-year records of CO2 flux were available and analyzed (2002-2005). Using the weather record of 2005 with optimizations from the other years, the standard deviation of annual GPP was estimated to be 171-206 gC m(-2) a(-1) (8-14%), of annual R-e 227-247 gC m(-2) a(-1)(14-16%) and of annual NEE 176-276 gC m(-2) a(-1). The inter-site standard deviation was higher for GPP and R-e, 534 gC m(-2) a(-1) (37.3%) and 486 gC m(-2) a(-1) (34.8%), respectively. However, the inter-site standard deviation of NEE was similar to the interannual one, amounting to 207 gC m-2a-1. Large differences occur due to soil type. The grasslands on organic (peat) soils show a mean net release of CO2 of 220 +/- 90 g C m(-2) a(-1) while the grasslands on mineral (clay and sand) soils show a mean net uptake of CO2 of 90 +/- 90 g C m(-2) a(-1). If a weighing with the fraction of grassland on organic (20%) and mineral soils (80%) is applied, an average NEE of 28 +/- 90 g C m(-2) a(-1) is found. The results from the analysis illustrate the need for regionally specific and spatially explicit CO2 emission estimates from grassland

Variability of annual CO₂ exchange from Dutch Grasslands

Si la protection des droits fondamentaux constitue « l’élément essentiel au succès à long terme de la lutte contre le terrorisme », il est, dès lors, essentiel de préciser l’obligation pour les organisations internationales de répondre de leurs actes en cas de violation des droits de l’homme, en particulier dans le cas de l’édiction et de la mise en oeuvre de sanctions ciblées. Cela suppose que soient précisées les obligations applicables aux organisations en matière de droits de l’homme, ainsi que les conditions et mécanismes de la mise en oeuvre de leur responsabilité internationale. À cet égard, nous pourrons souligner un certain nombre d’insuffisances d’ordre théorique et pratique, ce qui nous conduira à nous interroger sur d’autres solutions et en particulier celle qui consisterait à engager la responsabilité des Etats pour les actes des organisations dont ils sont membres et qui ne respecteraient pas les droits fondamentaux.If the fundamental rights protection constitutes an “essential element for the success in the long term fight against terrorism”, it is therefore an essential duty of international organizations to response of their actions in case of human rights violations and in particular, the case of ediction and implementation of targeted sanctions. It is supposed that organizations obligations on human rights must be specified and the conditions and mechanisms for the implementation of their international responsibility as well. In this respect, we can highlight some number of theoretical and practical shortcomings which will lead us to reflect on other solutions and in particular the one that would consist to engage government responsibility for organizations actions of which they are members and which would not respect the fundamental rights.Si la protección de los derechos fundamentales constituye "el elemento esencial al éxito a largo plazo de la lucha contra el terrorismo", es esencial, desde entonces, precisar la obligación para los organismos internacionales de responder de sus actos en caso de violación de los derechos humanos, en particular en el caso de la elaboración y de la puesta en ejecución de sanciones dirigidas. Esto supone que sean precisadas las obligaciones aplicables a las organizaciones en materia de derechos humanos, así como las condiciones y los mecanismos de la puesta en ejecución de su responsabilidad internacional. A este respecto, podremos subrayar un cierto número de insuficiencias de orden teórica y práctica, lo que nos conducirá a interrogarnos sobre otras soluciones y en particular lo que consistiría en comprometer la responsabilidad de los Estados para los actos de las organizaciones de las que son miembros y que no respetan los derechos fundamentales

Variability of annual CO₂ exchange from Dutch grasslands

An intercomparison is made of the Net Ecosystem Exchange of CO₂, <i>NEE</i>, for eight Dutch grassland sites: four natural grasslands, two production grasslands and two meteorological stations within a rotational grassland region. At all sites the <i>NEE</i> was determined during at least 10 months per site, using the eddy-covariance (EC) technique, but in different years. The <i>NEE</i> does not include any import or export other than CO₂. The photosynthesis-light response analysis technique is used along with the respiration-temperature response technique to partition <i>NEE</i> into Gross Primary Production (<i>GPP</i>) and Ecosystem Respiration (<i>R_e</i>) and to obtain the eco-physiological characteristics of the sites at the field scale. Annual sums of <i>NEE</i>, <i>GPP</i> and <i>R_e</i> are then estimated using the fitted response curves with observed radiation and air temperature from a meteorological site in the centre of The Netherlands as drivers. These calculations are carried out for four years (2002&ndash;2005). Land use and management histories are not considered. The estimated annual <i>R_e</i> for all individual sites is more or less constant per site and the average for all sites amounts to 1390&plusmn;30 gC m^&minus;2 a^&minus;1. The narrow uncertainty band (&plusmn;2%) reflects the small differences in the mean annual air temperature. The mean annual <i>GPP</i> was estimated to be 1325 g C m^&minus;2 a^&minus;1, and displays a much higher standard deviation, of &plusmn;110 gC m^&minus;2 a^&minus;1 (8%), which reflects the relatively large variation in annual solar radiation. The mean annual <i>NEE</i> amounts to &ndash;65&plusmn;85 gC m^&minus;2 a^&minus;1. From two sites, four-year records of CO₂ flux were available and analyzed (2002&ndash;2005). Using the weather record of 2005 with optimizations from the other years, the standard deviation of annual <i>GPP</i> was estimated to be 171&ndash;206 gC m^&minus;2 a^&minus;1 (8&ndash;14%), of annual <i>R_e</i> 227&ndash;247 gC m^&minus;2 a^&minus;1 (14&ndash;16%) and of annual <i>NEE</i> 176&ndash;276 gC m^&minus;2 a^&minus;1. The inter-site standard deviation was higher for <i>GPP</i> and <i>R_e</i>, 534 gC m^&minus;2 a^&minus;1 (37.3%) and 486 gC m^&minus;2 a^&minus;1 (34.8%), respectively. However, the inter-site standard deviation of <i>NEE</i> was similar to the interannual one, amounting to 207 gC m^&minus;2 a^&minus;1. Large differences occur due to soil type. The grasslands on organic (peat) soils show a mean net release of CO₂ of 220&plusmn;90 g C m^&minus;2 a^&minus;1 while the grasslands on mineral (clay and sand) soils show a mean net uptake of CO₂ of 90&plusmn;90 g C m^&minus;2 a^&minus;1. If a weighing with the fraction of grassland on organic (20%) and mineral soils (80%) is applied, an average <i>NEE</i> of 28 &plusmn;90 g C m^&minus;2 a^&minus;1 is found. The results from the analysis illustrate the need for regionally specific and spatially explicit CO₂ emission estimates from grassland

Greenhouse gas fluxes of agricultural soils in Finland

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