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Dans un contexte de changement climatique, le fonctionnement de la biosphère continentale peut être durablement affecté par l’augmentation d’extrêmes climatiques, diminuant l’assimilation photosynthétique du carbone ou augmentant la respiration de l’écosystème. Quantifier le stockage de carbone par les écosystèmes et prédire leur sensibilité aux changements climatiques repose donc fortement sur notre capacité à diagnostiquer séparément les flux de photosynthèse et de respiration à différentes échelles. La productivité primaire brute (GPP) n’est cependant pas directement mesurable. Des approches indirectes ont été proposées pour estimer les flux bruts biosphériques (GPP et respiration), combinant différents traceurs et notamment les isotopologues stables du CO2 (13C et 18O), et, plus récemment, la mesure de l’oxysulfure de carbone dans l’atmosphère (COS). Dans ce contexte, mes travaux de thèse ont exploré deux approches. La première visant à utiliser les mesures isotopiques des cernes d’arbres et leur largeur, toutes liées aux variations de l’activité photosynthétique. Les variations interannuelles du flux de photosynthèse modélisées par un modèle de biosphère continentale ont ainsi pu être évaluées et comparées aux mesures in situ. La seconde visant utiliser les mesures atmosphériques de COS pour contraindre les estimations de GPP des modèles actuels de biosphère, en (1) établissant un nouveau bilan global des sources et puits de ce gaz, (2) optimisant les différents termes de sources et puits de COS et (3) estimant le potentiel de ce nouveau traceur pour valider/invalider les flux bruts de photosynthèse (GPP) simulés par les modèles actuels de biosphère continentale. / In the context of global climate change, the behavior of the terrestrial biosphere can be durably affected by the increased frequency and intensity of extreme climatic events, which can decrease the photosynthetic assimilation of carbon and/or increase the respiration rate of the ecosystems. Therefore, quantifying the carbon storage capacity of the ecosystems and predicting their sensitivity to climate changes strongly rely on our capacity to separately estimate the photosynthesis and respiration rates at different scales. The gross primary productivity (GPP) is however not directly measurable. Indirect approaches have been proposed to estimate the biospheric gross fluxes (GPP and respiration), combining for instance stable isotopologues of CO2 (13C and 18O), and, more recently, the measure of carbonyl sulfide (COS) concentrations in the atmosphere. In this context, my PhD work followed two complementary approaches. In the first approach, isotopic measurements and tree-ring widths were used, because both of them are linked to the photosynthetic activity. The inter-annual variations of the photosynthetic fluxes simulated with the ORCHIDEE continental biosphere model were evaluated and compared with in situ measurements. The second approach consisted in using atmospheric measurements of OCS concentrations and in exploring their potential to constrain the current estimates of the GPP in dynamic global vegetation models (DGVM), by (1) establishing a new global budget of sources and sinks of this gas, (2) optimizing the source and sink terms of this cycle and (3) estimating the potential of this new tracer to validate/invalidate the simulated GPP when using current DGVMs.

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My diploma thesis is focused on the subject of biosphere reserves, as an example of special protected areas, with special regard to BR Šumava. There is examined its current situation and its contribution to sustainable development. At the same time there are being found out the opinions, attitudes and expectations of key local stakeholders and other persons and organizations concerned towards the institution BR Šumava. This thesis deals with optimal functioning model of BR Šumava and its future sustainable development.

There are increased ‘calls to reconnect humanity with the biosphere’ to respond to the current environmental crisis. The formative potential of nature experiences for individual’s development of connectedness with nature therefore requires attention. Specifically, connecting children with nature through nature experiences could be a leverage point for sustainable development. This thesis explores the temporal dimension of nature experiences, i.e. nature routines, for young children from a socialecological systems perspective. The views of experienced pedagogues in Swedish outdoors preschools are addressed. The results show that affective connectedness with nature develops in four general phases: being comfortable in nature, enjoy being in nature, caring for nature and oneness with nature, while experiential and cognitive connectedness with nature develop gradually. There is a progression in the pedagogically designed nature routines during the time at the preschool, as pedagogues facilitate relevant learning situations in nature to support the on-going development of children’s connectedness with nature. Nature routines are understood as generating enculturation on how to be and behave in nature. Furthermore, pedagogues’ functional classification of nature places highlights the pedagogical values of varying natural environments and biotopes near the preschool. Implications for urban planning could therefore be investigated further. Future research could also address the relevance of nature routines and the phases of affective connectedness with nature for other age groups.

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