The Virginia Tech Universal Classifier Synchronizer (UCS) system can enable a cognitive receiver to detect, classify and extract all the parameters needed from a received signal for physical layer demodulation and configure a cognitive radio accordingly. Currently, UCS can process analog amplitude modulation (AM) and frequency modulation (FM) and digital narrow band M-PSK, M-QAM and wideband signal orthogonal frequency division multiplexing (OFDM). A fully developed prototype of UCS system was designed and implemented in our laboratory using GNU radio software platform and Universal Software Radio Peripheral (USRP) radio platform. That system introduces a lot of latency issues because of the limited USB data transfer speeds between the USRP and the host computer. Also, there are inherent latencies and timing uncertainties in the General Purpose Processor (GPP) software itself. Solving the timing and latency problems requires running key parts of the software-defined radio (SDR) code on a Field Programmable Gate Array (FPGA)/Digital Signal Processor (DSP)/GPP based hybrid platform. Our objective is to port the entire UCS system on the Lyrtech SFF SDR platform which is a hybrid DSP/FPGA/GPP platform. Since the FPGA allows parallel processing on a wideband signal, its computing speed is substantially faster than GPPs and most DSPs, which sequentially process signals. In addition, the Lyrtech Small Form Factor (SFF)-SDR development platform integrates the FPGA and the RF module on one platform; this further reduces the latency in moving signals from RF front end to the computing component. Also for UCS to be commercially viable, we need to port it to a more portable platform which can be transitioned to a handset radio in the future. This thesis is a proof of concept implementation of the coarse classifier which is the first step of classification. Both fixed point and floating point implementations are developed and no compiler specific libraries or vendor specific libraries are used. This makes transitioning the design to any other hardware like GPPs and DSPs of other vendors possible without having to change the basic framework and design. / Master of Science

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The turbulent fluxes of carbon dioxide (CO2 ) were investigated in two sites of irrigated rice in southern Brazil, using the eddy covariance technique over 385 days of analysis at the site of Paraiso do Sul and 683 days in site Cachoeira do Sul also used the model of filling the gaps in order to estimate the net ecosystem exchange CO2 -C (NEE). Throughout the growing season, rice fields, both for the site of Paraiso do Sul to the site of Cachoeira do Sul, acted as carbon sinks (C). During fallow periods, these fields were the source of C. The NEE accumulated at the site of Cachoeira do Sul was similar in both cycles and practically equal to the estimated site of Paraiso do Sul. The GPP accumulated during the crop cycle 2010-2011, the rice field of Cachoeira do Sul, was less than 12% of the 2011-2012 cycle and higher than 15% of the site of Paraiso do Sul. The Re accumulated was similar at the site of Paraíso do Sul in the 2010-2011 cycle Cachoeira do Sul, but less than the 2011- 2012 cycle. The values of NEE, GPP and R e for the site of Paraíso do Sul were - 270.53 gCm2 , -821.19gCm2 and 527.59gCm2 , respectively. To the site of Cachoeira do Sul, were -282,53 gCm2 , -933,40gCm2 and 597,05gCm2 for NEE, GPP and Re , respectively, in the 2010-2011 cycle. For the 2011-2012 cycle in the rice field of Cachoeira do Sul, the values of NEE, GPP and Re were -279,69gCm2 , - 1062,64gCm2 and 716,58gCm2 , respectively. The total C accumulated over the period analyzed for the site of Paraíso do Sul was -45,90gCm2 , considering this area of rice cultivation, as a sink for C. While the growing area of Cachoeira do Sul was considered a source of C (19,94 gCm2 ). Showing by this that long periods of fallow contribute significantly to the accumulated fluxes due to constant presence of vegetation. The contribution of this work will assist in the investigation of CO2 in these ecosystems. / Os fluxos turbulentos de dióxido de carbono (CO2 ) foram investigados em dois sítios de cultura de arroz irrigado no Sul do Brasil, utilizando a técnica de covariância de vórtices ao longo de 385 dias de análise no sítio de Paraíso do Sul e de 683 dias, no sítio de Cachoeira do Sul. Além disso, utilizou-se o modelo de preenchimento das lacunas com o objetivo de estimar a troca líquida de C-CO2 no ecossistema (NEE). Ao longo do período de cultivo, os campos de arroz, tanto para o sítio de Paraíso do Sul quanto para o sítio de Cachoeira do Sul, atuaram como sumidouros de carbono (C). Durante os períodos de pousio, esses campos foram fontes de C. O NEE acumulado, no sítio de Cachoeira do Sul foi semelhante em ambos os ciclos e praticamente igual ao estimado no sítio de Paraíso do Sul. A GPP acumulada durante o ciclo de cultivo de 2010-2011, no campo de arroz de Cachoeira do Sul, foi inferior a 12% do ciclo de 2011-2012 e superior em 15% a do sítio de Paraíso do Sul. A Re acumulada foi semelhante no sítio de Paraíso do Sul e no ciclo de 2010- 2011 de Cachoeira do Sul, mas inferior a do ciclo de 2011-2012. Os valores de NEE, GPP e Re para o sítio de Paraíso do Sul foram de -270,53 gCm2 , -821,19gCm2 e 527,59gCm2 , respectivamente. Para o sítio de Cachoeira do Sul, foram de - 282,53gCm2 , -933,40gCm2 e 597,05gCm2 para NEE, GPP e Re , respectivamente, no ciclo de 2010-2011. Para o ciclo de 2011-2012, no campo de arroz de Cachoeira do Sul, os valores de NEE, GPP e Re foram de -279,69gCm2 , - 1062,640gCm2 e 716,58gCm2 , respectivamente. O total de C acumulado ao longo do período analisado para o sítio de Paraíso do Sul foi de -45,90gCm2 , considerando esta área de cultivo de arroz, como um sumidouro de C. Enquanto que a área de cultivo de Cachoeira do Sul foi considerada fonte de C (19,94 gCm2 ). Mostrando com isso, que períodos longos de pousio contribuem consideravelmente para os fluxos acumulados devido a permanência constante de vegetação. A contribuição deste trabalho auxiliará na investigação das emissões de CO2 nesses ecossistemas.

Este trabalho parte da hipótese que a hidrodinâmica influencia o metabolismo de um lago. Para testar esta hipótese, este estudo utilizou uma estratégia numérica baseada em processos para avaliar o efeito da hidrodinâmica (governada pelo vento) sobre as estimativas de metabolismo (GPP, NEP e R) considerando a heterogeneidade espacial da lagoa Mangueira, um grande lago raso subtropical na costa sul do Brasil. O efeito da hidrodinâmica dominada pelo vento no metabolismo foi avaliado pela mudança da série de vento original (direção e intensidade), totalizando cinco novos cenários de vento. A avaliação espacial foi desenvolvida em quatro áreas (Norte, Centro, Sul e a lagoa como um todo) e em zonas biológicas (zona limnética e zona litorânea). Os resultados indicaram que há diferenças nas estimativas de metabolismo (GPP, NEP e R) entre as regiões da lagoa Mangueira considerando a situação com a série de vento original. Em geral, a diferença média nas estimativas de metabolismo entre a região Norte e a região Sul foi de 3,81 mgO2/m³/dia (p-value<0,05) para o GPP, 3,32 mgO2/m³/dia para R (p-value<0,05) e 0,49 mgO2/m³/dia (p-value<0,05) para NEP. A diferença entre a zona litorânea e a zona limnética na lagoa Mangueira como um todo foi de 10,1 mgO2/m³/dia para GPP, para R foi de 1,3 mgO2/m³/dia e para NEP foi de 8,8 mgO2/m³/dia. O metabolismo geral da lagoa também apresentou variações sazonais, alternando entre períodos autotróficos (NEP>0, em 41,0 % do tempo) e períodos heterotróficos (NEP<0, em 59,0 % do tempo). As estimativas de metabolismo da Lagoa Mangueira e nas regiões delimitadas se mostraram sensíveis a alterações no vento. Cada área delimitada apresentou resposta diferente às alterações nas séries de vento. Os cenários de vento testados mostram que a hidrodinâmica causa diferenças significativas no metabolismo da Lagoa Mangueira. O balanço de oxigênio neste ecossistema foi influenciado pela taxa de reaeração, pela produção primária e pela respiração do fitoplâncton. Os outros processos considerados no balanço de oxigênio não demonstraram contribuições importantes para o metabolismo geral do ecossistema. / The hypothesis of this work is that hydrodynamics can alter the lake metabolism. To evaluate this hypothesis this study used a process-based strategy for evaluating the effect of wind-driven hydrodynamics on estimates of lake metabolism (GPP, R, and NEP) considering the spatial heterogeneity in Lake Mangueira, a subtropical grate lake in southern coast of Brazil. The effect of wind-driven hydrodynamics over the lake metabolism was evaluated by changes in the original wind series (direction and intensity), totalizing five new sets of wind scenarios. The spatial evaluation was carried in four different areas (North, Center, South, and the lake as a whole) and in two different biological zones (littoral zone and limnetic zone). Our findings indicate that there are differences on estimates of lake metabolism between the four areas taking into account the original wind time series. In general, the differences on lake metabolism estimates between the Norte region and the South region was 3.81 mgO2/m³/day (p-value<0,05) for GPP, 3.32 mgO2/m³/day (p-value<0,05) for R, and 0.49 mgO2/m³/day (p-value<0,05) for NEP. The difference between the littoral zone and the limnetic zone in the Lake Mangueira as a whole was 10.1 mgO2/m³/day for GPP, 1.3 mgO2/m³/day for R, and 8.8 mgO2/m³/day for NEP. The overall lake metabolism also presented seasonal variations, alternating among autotrophic periods (NEP>0, 41.0% of the time), and heterotrophic periods (NEP<0, 59.0% of the time). Estimates of lake metabolism in Lake Mangueira as a whole were sensitive to changes in the wind time series. Each area showed different response to the changes in wind time series. The tested sets of wind scenarios showed that wind-driven hydrodynamics can significantly alter the Lake Mangueira metabolism estimates. The overall oxygen balance in this system was mostly influenced by reaeration, and by the primary production and respiration of phytoplankton. The other processes considered in the oxygen balance showed no significant contributions to the overall metabolism of the ecosystem.

Este trabalho parte da hipótese que a hidrodinâmica influencia o metabolismo de um lago. Para testar esta hipótese, este estudo utilizou uma estratégia numérica baseada em processos para avaliar o efeito da hidrodinâmica (governada pelo vento) sobre as estimativas de metabolismo (GPP, NEP e R) considerando a heterogeneidade espacial da lagoa Mangueira, um grande lago raso subtropical na costa sul do Brasil. O efeito da hidrodinâmica dominada pelo vento no metabolismo foi avaliado pela mudança da série de vento original (direção e intensidade), totalizando cinco novos cenários de vento. A avaliação espacial foi desenvolvida em quatro áreas (Norte, Centro, Sul e a lagoa como um todo) e em zonas biológicas (zona limnética e zona litorânea). Os resultados indicaram que há diferenças nas estimativas de metabolismo (GPP, NEP e R) entre as regiões da lagoa Mangueira considerando a situação com a série de vento original. Em geral, a diferença média nas estimativas de metabolismo entre a região Norte e a região Sul foi de 3,81 mgO2/m³/dia (p-value<0,05) para o GPP, 3,32 mgO2/m³/dia para R (p-value<0,05) e 0,49 mgO2/m³/dia (p-value<0,05) para NEP. A diferença entre a zona litorânea e a zona limnética na lagoa Mangueira como um todo foi de 10,1 mgO2/m³/dia para GPP, para R foi de 1,3 mgO2/m³/dia e para NEP foi de 8,8 mgO2/m³/dia. O metabolismo geral da lagoa também apresentou variações sazonais, alternando entre períodos autotróficos (NEP>0, em 41,0 % do tempo) e períodos heterotróficos (NEP<0, em 59,0 % do tempo). As estimativas de metabolismo da Lagoa Mangueira e nas regiões delimitadas se mostraram sensíveis a alterações no vento. Cada área delimitada apresentou resposta diferente às alterações nas séries de vento. Os cenários de vento testados mostram que a hidrodinâmica causa diferenças significativas no metabolismo da Lagoa Mangueira. O balanço de oxigênio neste ecossistema foi influenciado pela taxa de reaeração, pela produção primária e pela respiração do fitoplâncton. Os outros processos considerados no balanço de oxigênio não demonstraram contribuições importantes para o metabolismo geral do ecossistema. / The hypothesis of this work is that hydrodynamics can alter the lake metabolism. To evaluate this hypothesis this study used a process-based strategy for evaluating the effect of wind-driven hydrodynamics on estimates of lake metabolism (GPP, R, and NEP) considering the spatial heterogeneity in Lake Mangueira, a subtropical grate lake in southern coast of Brazil. The effect of wind-driven hydrodynamics over the lake metabolism was evaluated by changes in the original wind series (direction and intensity), totalizing five new sets of wind scenarios. The spatial evaluation was carried in four different areas (North, Center, South, and the lake as a whole) and in two different biological zones (littoral zone and limnetic zone). Our findings indicate that there are differences on estimates of lake metabolism between the four areas taking into account the original wind time series. In general, the differences on lake metabolism estimates between the Norte region and the South region was 3.81 mgO2/m³/day (p-value<0,05) for GPP, 3.32 mgO2/m³/day (p-value<0,05) for R, and 0.49 mgO2/m³/day (p-value<0,05) for NEP. The difference between the littoral zone and the limnetic zone in the Lake Mangueira as a whole was 10.1 mgO2/m³/day for GPP, 1.3 mgO2/m³/day for R, and 8.8 mgO2/m³/day for NEP. The overall lake metabolism also presented seasonal variations, alternating among autotrophic periods (NEP>0, 41.0% of the time), and heterotrophic periods (NEP<0, 59.0% of the time). Estimates of lake metabolism in Lake Mangueira as a whole were sensitive to changes in the wind time series. Each area showed different response to the changes in wind time series. The tested sets of wind scenarios showed that wind-driven hydrodynamics can significantly alter the Lake Mangueira metabolism estimates. The overall oxygen balance in this system was mostly influenced by reaeration, and by the primary production and respiration of phytoplankton. The other processes considered in the oxygen balance showed no significant contributions to the overall metabolism of the ecosystem.

Este trabalho parte da hipótese que a hidrodinâmica influencia o metabolismo de um lago. Para testar esta hipótese, este estudo utilizou uma estratégia numérica baseada em processos para avaliar o efeito da hidrodinâmica (governada pelo vento) sobre as estimativas de metabolismo (GPP, NEP e R) considerando a heterogeneidade espacial da lagoa Mangueira, um grande lago raso subtropical na costa sul do Brasil. O efeito da hidrodinâmica dominada pelo vento no metabolismo foi avaliado pela mudança da série de vento original (direção e intensidade), totalizando cinco novos cenários de vento. A avaliação espacial foi desenvolvida em quatro áreas (Norte, Centro, Sul e a lagoa como um todo) e em zonas biológicas (zona limnética e zona litorânea). Os resultados indicaram que há diferenças nas estimativas de metabolismo (GPP, NEP e R) entre as regiões da lagoa Mangueira considerando a situação com a série de vento original. Em geral, a diferença média nas estimativas de metabolismo entre a região Norte e a região Sul foi de 3,81 mgO2/m³/dia (p-value<0,05) para o GPP, 3,32 mgO2/m³/dia para R (p-value<0,05) e 0,49 mgO2/m³/dia (p-value<0,05) para NEP. A diferença entre a zona litorânea e a zona limnética na lagoa Mangueira como um todo foi de 10,1 mgO2/m³/dia para GPP, para R foi de 1,3 mgO2/m³/dia e para NEP foi de 8,8 mgO2/m³/dia. O metabolismo geral da lagoa também apresentou variações sazonais, alternando entre períodos autotróficos (NEP>0, em 41,0 % do tempo) e períodos heterotróficos (NEP<0, em 59,0 % do tempo). As estimativas de metabolismo da Lagoa Mangueira e nas regiões delimitadas se mostraram sensíveis a alterações no vento. Cada área delimitada apresentou resposta diferente às alterações nas séries de vento. Os cenários de vento testados mostram que a hidrodinâmica causa diferenças significativas no metabolismo da Lagoa Mangueira. O balanço de oxigênio neste ecossistema foi influenciado pela taxa de reaeração, pela produção primária e pela respiração do fitoplâncton. Os outros processos considerados no balanço de oxigênio não demonstraram contribuições importantes para o metabolismo geral do ecossistema. / The hypothesis of this work is that hydrodynamics can alter the lake metabolism. To evaluate this hypothesis this study used a process-based strategy for evaluating the effect of wind-driven hydrodynamics on estimates of lake metabolism (GPP, R, and NEP) considering the spatial heterogeneity in Lake Mangueira, a subtropical grate lake in southern coast of Brazil. The effect of wind-driven hydrodynamics over the lake metabolism was evaluated by changes in the original wind series (direction and intensity), totalizing five new sets of wind scenarios. The spatial evaluation was carried in four different areas (North, Center, South, and the lake as a whole) and in two different biological zones (littoral zone and limnetic zone). Our findings indicate that there are differences on estimates of lake metabolism between the four areas taking into account the original wind time series. In general, the differences on lake metabolism estimates between the Norte region and the South region was 3.81 mgO2/m³/day (p-value<0,05) for GPP, 3.32 mgO2/m³/day (p-value<0,05) for R, and 0.49 mgO2/m³/day (p-value<0,05) for NEP. The difference between the littoral zone and the limnetic zone in the Lake Mangueira as a whole was 10.1 mgO2/m³/day for GPP, 1.3 mgO2/m³/day for R, and 8.8 mgO2/m³/day for NEP. The overall lake metabolism also presented seasonal variations, alternating among autotrophic periods (NEP>0, 41.0% of the time), and heterotrophic periods (NEP<0, 59.0% of the time). Estimates of lake metabolism in Lake Mangueira as a whole were sensitive to changes in the wind time series. Each area showed different response to the changes in wind time series. The tested sets of wind scenarios showed that wind-driven hydrodynamics can significantly alter the Lake Mangueira metabolism estimates. The overall oxygen balance in this system was mostly influenced by reaeration, and by the primary production and respiration of phytoplankton. The other processes considered in the oxygen balance showed no significant contributions to the overall metabolism of the ecosystem.

Ongoing climate change is predicted to increase water temperatures and export of terrestrial dissolved matter (TDOM) to aquatic ecosystems influencing ecosystem productivity, food web dynamics and production of top consumers. Ecosystem productivity is mainly determined by the rates of primary production (GPP) in turn controlled by nutrients, light availability and temperature, while temperature alone affect vital rates like consumption and metabolic rates and maintenance requirements of consumers. Increased level of TDOM causes brownification of water which may cause light limitation in algae and decrease GPP and especially so in the benthic habitat. Temperature increase has a been suggested to increase metabolic rates of consumers to larger extent than the corresponding effect on GPP, which suggest reduced top consumer biomass and production with warming. The aim of this thesis was to experimentally study the effects of increased temperature and TDOM on habitat specific and whole ecosystem GPP and fish densities and production. In a replicated large-scale pond experiment encompassing natural food webs of lotic ecosystems I studied population level responses to warming and brownification in the three- spined stickleback (Gasterosteus aculeatus). Results showed overall that warming had no effect on whole ecosystem GPP, likely due to nutrient limitation, while TDOM input decreased benthic GPP but stimulated pelagic GPP. In fish, results first of all suggested that recruitment in sticklebacks over summer was negatively affected by warming as maintenance requirements in relation to GPP increased and thereby increased starvation mortality of young-of-the-year (YOY) sticklebacks. Secondly, brownification increased mortality over winter in YOY as the negative effect on light conditions likely decreased search efficiency and caused lower consumption rates and starvation over winter in sticklebacks. Third, seasonal production of YOY, older, and total stickleback production was negatively affected by warming, while increased TDOM caused decreased YOY and total fish production. The combined effect of the two was intermediate but still negative. Temperature effects on fish production were likely a result of increased energy requirements of fish in relation to resource production and intake rates whereas the negative effect of TDOM likely was a result of decreased benthic resource production. Finally, effects of warming over a three-year period caused total fish density and biomass and abundance of both mature and old fish to decrease, while proportion of young fish increased. The main cause behind the strong negative effects of warming on fish population biomass and changes in population demographic parameters were likely the temperature driven increased energy requirements relative to resource production and cohort competition. The results from this thesis suggest that predicted climate change impacts on lentic aquatic ecosystems will decrease future densities and biomass of fish and negatively affect fish production and especially so in systems dominated by benthic resource production.

Bakgrund: Mångmiljardbelopp spenderas varje år i onödan på offentliga upphandlingar, delvis på grund av bristande ekonomistyrning. Offentliga upphandlingar beräknas även stå för 28 procent av den totala klimatpåverkan för Sveriges konsumtion. Trots det finns det flera lagar som styr upphandlingar, exempelvis lagen om offentlig upphandling men den kan dock upplevas som tvetydig gällande miljöhänsyn. Syfte: Syftet med studien är att undersöka hur mindre kommuner implementerar miljöhänsyn i deras upphandlingar samt att ta reda på vilka faktorer som påverkar mindre kommuners möjligheter att utföra strategiska upphandlingar. Metod: Vi har utfört en kvalitativ undersökning för studien. Vi har utfört semistrukturerade intervjuer med upphandlingschefer eller ordföranden i kommunstyrelsen i 5 olika kommuner där datan som inhämtats har använts som grund i vår empiri.  Slutsats: Avslutningsvis konkluderar vi att alla intervjuade kommuner tar miljöhänsyn i beaktning vid upphandlingar men de har olika förutsättningar för att lyckas. Samverkan mellan kommuner är något som frekvent anges främja hållbarhet i upphandlingar medan kompetensutveckling och uppföljningar behöver utvecklas ytterligare. / Background: Billions of SEK are spent unnecessarily each year on public procurement, partly due to inadequate financial management. Public procurement is also estimated to account for 28 percent of Sweden's total carbon footprint from consumption. Despite this, there are several laws governing procurement, such as the Public Procurement Act, but it can be perceived as ambiguous regarding environmental considerations. Purpose: The purpose of the study is to investigate how smaller municipalities incorporate environmental considerations in their procurement processes and to identify the factors influencing smaller municipalities' ability to conduct strategic procurement. Method: We conducted a qualitative study for this research. We conducted semi-structured interviews with procurement managers or chairpersons of the municipal boards in five different municipalities, and the data collected from these interviews formed the basis of our empirical analysis. Conclusion: In conclusion, we find that all interviewed municipalities take environmental considerations into account in their procurement processes, but they have varying conditions for success. Collaboration between municipalities is frequently mentioned as a factor that promotes sustainability in procurement, while further development is needed in terms of competence development and monitoring.

No description available.

Le bilan carboné d'une rotation culturale de quatre ans a été établi entre 2004 et 2008 sur le site expérimental de Lonzée, Belgique. La région se caractérise par un climat tempéré océanique avec une température moyenne de l'air de 10°C et des précipitations annuelles de l'ordre de 800 mm. Le sol de la parcelle est un Luvisol. Les cultures composant la rotation sont des cultures de betterave, froment dhiver, pomme de terre et froment dhiver. Dans le but détablir un bilan carboné, des mesures ont été effectuées à différentes échelles spatiales et temporelles. Un système de mesure par eddy covariance fournit une estimation par demiheure de l'échange net en CO2 de l'écosystème (NEE). La qualité des procédures de sélection et de traitement des flux de NEE a été contrôlée. A partir de ces mesures, la productivité primaire brute (GPP) et la respiration totale de l'écosystème (TER) sont déduites. Plusieurs procédures basées sur les mesures diurnes ou nocturnes de NEE sont comparées. L'intérêt d'utiliser un court pas de temps dans ces procédures et la température du sol comme température de référence a été mis en avant, ainsi que la nécessité de déterminer une valeur seuil de la vitesse de friction (u*) pour chaque culture et les longues inter-cultures. Pour la culture de froment d'hiver 2005, une estimation de la GPP déduite des mesures d'eddy covariance est comparée à une estimation basée sur une modélisation de mesures réalisées, une fois par semaine, à l'échelle de la feuille. La conception initiale de l'appareil de mesure a permis de réaliser les mesures sur les feuilles uniquement. Les évolutions des deux estimations sont proches à l'échelle de la saison et à l'échelle journalière. La mise en oeuvre de la méthode basée sur les mesures à léchelle de la feuille a apporté dimportantes informations en termes de réponse de la GPP aux facteurs climatiques et non climatiques et a permis une validation de lestimation basée sur les mesures deddy covariance. Toutefois, dans le cadre de létablissement dun bilan carboné, la méthode basée sur les mesures d'eddy covariance est préférée. Des mesures de la respiration de sol, réalisées à l'échelle de la miniparcelle de sol, et des mesures du contenu en carbone des plantes sont aussi réalisées. Combinées aux mesures d'eddy covariance, ces mesures permettent de déduire les parts autoet hétérotrophiques de la respiration. Sur l'ensemble de la rotation, la parcelle apparait être une source significative de carbone de 0.17 (+/- 0.14) kg C m-2. Cela suggère que, durant la rotation, le contenu en carbone du sol a diminué. Ceci peut sexpliquer par labsence dapport de fertilisation organique durant les 10 dernières années ainsi que par la récolte systématique des pailles des céréales.