Chemical species carry information in two dimensions, in their concentrations and their isotopic signatures. The concentrations of metabolites or synthetic compounds describe the composition of a chemical or biological system, while isotopic signatures describe processes in the system by their reaction pathways, regulation, and responses to external stimuli. Stable isotopes are unique tracers of these processes because their natural abundances are modulated by isotope effects occurring in physical processes as well as in chemical reactions. Nuclear magnetic resonance (NMR) spectroscopy is a prime technique not only for identification and quantification of small molecules in complex systems but also for measuring intramolecular distribution of stable isotopes in metabolites and other small molecules. In this thesis, we use quantitative NMR in three fields: in food science, environmental pollutant tracing, and plant-climate science. The phospholipid (PL) composition of food samples is of high interest because of their nutritional value and technological properties. However, the analysis of PLs is difficult as they constitute only a small fraction of the total lipid contents in foods. Here, we developed a method to identify PLs and determine their composition in food samples, by combining a liquid-liquid extraction approach for enriching PLs, with specialized 31P,1H-COSY NMR experiments to identify and quantify PLs. Wide-spread pollution with synthetic compounds threatens the environment and human health. However, the fate of pollutants in the environment is often poorly understood. Using quantitative deuterium NMR spectroscopy, we showed for the nitrosamine NDMA and the pesticide DDT how intramolecular distributions (isotopomer patterns) of the heavy hydrogen isotope deuterium reveal mechanistic insight into transformation pathways of pollutants and organic compounds in general. Intramolecular isotope distributions can be used to trace a pollutant’s origin, to understand its environmental transformation pathways and to evaluate remediation approaches. The atmospheric CO2 concentration ([CO2]) is currently rising at an unprecedented rate and plant responses to this increase in [CO2] influence the global carbon cycle and will determine future plant productivity. To investigate long-term plant responses, we developed a method to elucidate metabolic fluxes from intramolecular deuterium distributions of metabolites that can be extracted from historic plant material. We show that the intramolecular deuterium distribution of plant glucose depends on growth [CO2] and reflects the magnitude of photorespiration, an important side reaction of photosynthesis. In historic plant samples, we observe that photorespiration decreased in annual crop plants and natural vegetation over the past century, with no observable acclimation, implying that photosynthesis increased. In tree-ring samples from all continents covering the past 60 – 700 years, we detected a significantly smaller decrease in photorespiration than expected. We conclude that the expected “CO2 fertilization” has occurred but was significantly less pronounced in trees, due to opposing effects. The presented applications show that intramolecular isotope distributions not only provide information about the origin and turnover of compounds but also about metabolic regulation. By extracting isotope distributions from archives of plant material, metabolic information can be obtained retrospectively, which allows studies over decades to millennia, timescales that are inaccessible with manipulation experiments.

Submitted by Helena Alves do Prado null (helenapradoeco@gmail.com) on 2017-12-08T19:34:27Z No. of bitstreams: 1 Dissertação_HAP.pdf: 5105198 bytes, checksum: 05421b9dc8b38cd4f75d69d9f2066044 (MD5) / Approved for entry into archive by Adriana Aparecida Puerta null (dripuerta@rc.unesp.br) on 2017-12-11T16:34:40Z (GMT) No. of bitstreams: 1 prado_ha_me_rcla.pdf: 5105198 bytes, checksum: 05421b9dc8b38cd4f75d69d9f2066044 (MD5) / Made available in DSpace on 2017-12-11T16:34:40Z (GMT). No. of bitstreams: 1 prado_ha_me_rcla.pdf: 5105198 bytes, checksum: 05421b9dc8b38cd4f75d69d9f2066044 (MD5) Previous issue date: 2017-07-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A importância das florestas tropicais para o ciclo de carbono global e a incerteza de suas respostas a novas condições ambientais evidenciam a necessidade de aprofundar o conhecimento acerca de como as mudanças climáticas repercutirão nas dinâmicas florestais e nos processos fisiológicos associados. Essa dissertação, vinculada ao experimento AmazonFACE, objetiva avaliar como o incremento de CO2 atmosférico poderia repercutir na produtividade e eficiência no uso da água da Floresta Amazônica; se atributos funcionais envolvidos nesses processos (vcmax e g1) seriam modificados; e se ocorreriam mudanças na configuração funcional modelada da região. Para melhor caracterizar a diversidade funcional e as diferentes estratégias de sobrevivência adotadas pelas plantas em um ecossistema hiperdiverso, desenvolveu-se o CAETÊ (Carbon and Ecosystem Functional-Trait Evaluation Model) que, diferentemente dos modelos baseados em tipos funcionais, não parametriza a priori as possíveis combinações de atributos funcionais e simula um número superior de estratégicas de vida (PLS), sendo essas amostradas semi-aleatoriamente pelo modelo. Ao avaliar a performance do CAETÊ, verificou-se que a consideração de um número elevado de PLS – em vez de uma abordagem baseada em poucos tipos funcionais – simula maiores taxas de produtividade e condutância estomática; e que esse aumento tende à estabilização, com o aumento de estratégias consideradas. A aplicação do modelo foi feita utilizando a concentração de CO2 a ser empregada no AmazonFACE, de 600 ppm. Nas simulações, verificou-se uma redução nos valores médios de vcmax e g1, assim como uma modificação nos seus padrões de distribuição. Essas alterações associaram-se a um incremento nas taxas modeladas de produtividade e no uso da água, nas florestas tropicais, próximo a 13.5% (GPP) e 14.2% (NPP); redução de 3.8% na condutância estomática; e maior eficiência no uso da água (+21.1%). O enriquecimento da atmosfera também esteve associado à redução de ~5.5% na riqueza funcional. À medida que se avança para condições ambientais sem precedentes, torna-se de grande valia o uso de novas abordagens pelos modelos vegetacionais, que possibilitem a consideração de um número superior de estratégias de sobrevivência das plantas; e a captação de possíveis alterações nas respostas de atributos funcionais essenciais e, consequentemente, na riqueza funcional dos ecossistemas. As florestas tropicais desempenham um papel essencial nessas dinâmicas, uma vez que, além de hiperdiversas, são centrais para o ciclo de carbono global. / The importance of tropical forests in the global carbon cycle and the uncertainty of the forest’s responses to new environmental conditions evidence the necessity of deepening our knowledge about how climate changes affect forest dynamics and the associated physiological processes. This dissertation, linked to the AmazonFACE experiment, aims to evaluate how increasing atmospheric levels of CO2 could influence primary productivity and water use efficiency of the Amazon Forest; if functional traits involved in such processes (vcmax e g1) would be modified; and if changes would occur in the region’s modeled functional configuration. Aiming for a better characterization of the functional diversity and the different survival strategies adopted by plants in a hyperdiverse ecosystem, we developed the CAETÊ (Carbon and Ecosystem Functional-Trait Evaluation Model) which, unlike models based on functional types, does not perform a priori parameterization of the possible combinations of functional traits and simulates a superior amount of life strategies (PLS), that are semi-randomly sampled by the model. When evaluating CAETÊ’s performance, we verified that the consideration high number of PLS – instead of a framework based in few functional types – simulates higher amounts of productivity and stomatal conductance; and that such increase tends to stabilization when more strategies are considered. The model was applied using the CO2 concentration to be used in AmazonFACE – 600ppm. Simulations showed a reduction in the average values of de vcmax and g1, as well as a change in their patterns of distribution. Such alterations are associated to an increase in modeled values of productivity and water use of tropical forests close to 13.5% (GPP) and 14.2% (NPP), a reduction of 3.8% in stomatal conductance, and higher efficiency in water use (+21.1%). The atmospheric enrichment was also associated with a ~5.5% reduction in the functional richness. As the environment advances to unprecedented conditions, it becomes clear how worthy is the use of new approaches by vegetational models that enable consideration of higher numbers of plant survival strategies; and the uptake of possible changes in responses of essential functional traits, therefore, in the functional richness of the environment. The tropical forests influence deeply such dynamics; once beyond hyperdiverse.

<p>Kvantifikovanjem uticaja klimatskih promena na biljnu proizvodnju stiče se mogućnost obrazovanja dugoročnih planova u poljoprivrednoj proizvodnji kako bi se održao visok i stabilan prinos ključnih gajenih kutura (p&scaron;enice, kukuruz). Najpre su urađene analize klime i agroklimatskih pokazatelja za sada&scaron;nje uslove 1971-2000. i očekivane uslove za 2030. i 2050. godinu za 11 lokaliteta Republike Srbije. Tek nakon analize klime uzima se u obzir poznata činjenica da postoji međusobna interakcija između meteorolo&scaron;kih uslova, zemlji&scaron;ta i biljke. Na ovoj interakciji zasnivaju se modeli biljne proizvodnje i upotrebljavaju se u cilju kvantifikovanja uticaja klimatskih promena na biljnu proizvodnju tj. na dinamiku vegetacije i prinos.<br />U radu su kori&scaron;ćeni osmotreni dnevni meteorolo&scaron;ki podaci sa jedanaest stanica sakupljenih u Republičkom Hidrometeorolo&scaron;kom Zavodu Srbije. Za buduće stanje klime kori&scaron;ćeni su izlazni podaci globalnih klimatskih modela (ECHAM, HadCM, NCAR) i njihovom statističkom regionalizacijom Met &amp; Roll vremenskim generatorom dobijeni su podaci o budućem stanju klime na području jedanaest izabranih lokaliteta. Podaci o zemlji&scaron;tu (mehaničke i hemijske osobine) preuzeti su od Agencije za za&scaron;titu životne sredine iz Beograda. Ulazni podaci o biljnoj vrsti i njenoj agrotehnologiji, neophodni u radu sa modelom biljne proizvodnje (kalibraciji i validaciji), obezbeđeni su sa vi&scaron;egodi&scaron;njih ogleda zasnovanih na oglednim poljima Rimskih &Scaron;ančeva Insituta za ratarstvo i povrtarstvo u Novom Sadu.<br />Kao metod kori&scaron;ćeni su modeli za određivanje agroklimatskih parametara Agriclim i model biljne proizvodnje DSSAT v. 4.2.<br />4<br />Analizom buduće klime, temperature vazduha i padavina, utvrđeno je da se može očekivati porast temperature vazduha na godi&scaron;njem nivou i tokom svih delova vegetacinog perioda, a količina padavina se očekuje da bude vi&scaron;a tokom zimskog perioda, dok u prolećnom periodu (mart &ndash; april - maj) ne&scaron;to niža do 10 mm, a tokom letnjih meseci jun-jul-avgust značajno niža.<br />Analizom rezultata DSSAT 4.2 modela biljne proizvodnje, utvrđeno je da u očekivanim klimatskim uslovima 2030. i 2050. godine pri koncentraciji CO2 od 330 ppm prinos zrna ozime p&scaron;enice ostaje nepromenjen u većini lokaliteta izuzev Kru&scaron;evcu, Somboru i Vranju gde prinos opada do 12% u 2030. i do 11% u 2050. godini. Uzrok visokih i stabilnih prinosa su povećane količine padavina i povećanje temperature vazduha u zimskom periodu, manji broj mraznih i ledenih dana. Jedan od najvažnijih faktora stabilnosti prinosa je i dovoljna količina rezerve vlage u zemlji&scaron;tu za prolećni period i količina padavina za prolećni period, koji je u literaturi određen kao kritični period potrebe p&scaron;enice za vodom. U budućim uslovima analizom rezultata broja dana potrebnih od setve do cvetanja i od setve do zrelosti, ustanovljeno je da se očekuje manji broj dana, tj. da će fenofaze kraće trajati do cvetanja i zrelosti &scaron;to je posledica očekivanih vi&scaron;ih temperatura vazduha i suma efektivnih temperatura. U uslovima 2030. i 2050. godine i očekivane koncentracije CO2 po IPCC izve&scaron;taju iz 2007. godine, uticaj povi&scaron;ene koncentracije CO2 na prinos zrna p&scaron;enice je pozitivan. Prinosi kod većine lokaliteta ostaju nepromenjeni dok je mali pad prinosa zrna bio primećen na lokalitetima Kru&scaron;evac i Sombor, gde neznatno opada do 7% u 2030. godini i 2050. godini. U Somboru se očekuje nepromenjena količina padavina za mart &ndash; april - maj period i mnogo manja količina padavina u periodu jun &ndash; jul - avgust, a u Kru&scaron;evcu ne&scaron;to manja količina padavina u periodu mart &ndash; april &ndash; maj i do 40% manja količina u periodu jun &ndash; jul - avgust u 2050. godini.<br />Analizom rezultata prinosa zrna kukuruza za 2030. i 2050. godinu pri koncentracije CO2 od 330 ppm dobijen je veoma značajan pad prinosa i u uslovima bez navodnjavanja i u uslovima navodnjavanja normom od 180 mm za sve lokalitete. U 2030. i 2050. godini u uslovima povi&scaron;ene koncentracije CO2 uticaj očekivane koncentracije CO2 na prinos zrna kukuruza simulacijama ocenjen je kao negativan, jer je dobijeni prinos zrna kukuruza bio jo&scaron; niži nego pri koncentraciji CO2 od 330 ppm.<br />Veoma značajan pad prinosa posledica je vi&scaron;ih temperatura vazduha u JJA periodu, povećanja fiziolo&scaron;kog stresa kod biljaka usled povećanja broja letnjih i tropskih dana, značajno smanjenje količine padavina, posebno u periodu jun &ndash; jul &ndash; avgust i povećanje broja su&scaron;nih dana tokom istog perioda. Analizom dužine trajanja vegetativne sezone za oba režima uzgajanja kukuruza moglo se zapaziti da se u budućim uslovima očekuje skraćenje perioda vegetacije zbog vi&scaron;ih temperatura vazduha i sume temperatura. Analizom rezultata simulacije prinosa zrna soje za 2030. i 2050. godinu pri koncentraciji CO2 od 330 ppm, očekuje se nepromenjen prinos zrna u lokalitetima Ćuprija, Ni&scaron;, Vranje i Prizren, ili neznatno vi&scaron;i do 9 % u lokalitetima Kraljevo, Kru&scaron;evac, Novi Sad, Sombor i Zaječar. Samo u istočnom lokalitetu Dimitrovgrad i centralnom Požega se očekuje značajno vi&scaron;i prinos do 14% u 2030. godini i do 23% u 2050. godini. U 2030. i 2050. godini pri povi&scaron;enoj koncentracije CO2 po IPCC izve&scaron;taju iz 2007. godine očekuje se veoma značajno vi&scaron;i prinos u svim lokalitetima, a posebno je nagla&scaron;eno u lokalitetima Dimitrovgrad i Požega gde su dobijene najniže srednje temperature vazduha za AMJ i JJA period, najmanji broj letnjih i tropskih dana. Nakon dobijenih rezultata prinosa zrna za izabrane biljne kulture, rezultati prinosa zrna kukuruza ukazivali su na potrebu definisanja i uvođenja mera adaptacija u dosada&scaron;nju agrotehnologiju. DSSAT model biljne proizvodnje je izabran u istraživanju i kvantifikovanju mera adpatacija, jer se potrebe i fiziolo&scaron;ke reakcije biljke u simulacijama mogu pratiti na dnevnom nivou (Wang et al., 2011). Kao mere adaptacije analizirane su adaptacija roka setve i navodnjavanje. Adaptacija roka setve urađena je za kukuruz u uslovima bez navodnjavanja, da bi se ocenio isključivo uticaj primene ranijeg roka setve na prinos, a ne i navodnjavanje. Na osnovu analize<br />5<br />rezultata relativne promene prinosa za sve lokalitete, pokazalo se da se u uslovima ranijeg roka setve očekuju vi&scaron;i prinosi nego u uslovima uobičajenog datuma setve. Međutim, u svim lokalitetima i dalje se očekuje veoma značajan pad prinosa, izuzev u Dimitrovgradu, Vranju i Prizrenu, gde se očekuje značajan porast u odnosu na prinose perioda 1971-2000. godina.<br />Na osnovu analize rezultata simuliranih prinosa za ozimu p&scaron;enicu, kukuruz i soju, konstatovano je da se p&scaron;enica može proizvoditi u uslovima bez navodnjavanja, a prolećni usevi kukuruz i soja bi morali da se navodnjavaju zbog očekivanog velikog smanjenja količine padavina u letnjem periodu. Da bi se procenila adekvatna norma navodnjavanja u proizvodnji kukuruza u simulacijama u DSSAT modelu biljne proizvodnje izabrana je opcija 50 % dostupne vode biljci. Simulacije proizvodnje kukuruza u uslovima 50% dostupne vode biljci dale su pozitivne rezultate prinosa. Prinosi su bili nepromenjeni u lokalitetima Ćuprija, Kru&scaron;evac, Kraljevo, Ni&scaron;, Novi Sad, Sombor, Vranje, Zaječar u 2030. godini i 2050. godini izuzev u Kraljevu gde je prinos bio niži do 17% u 2050. godini. U lokalitetima Dimitrovgrad, Požega i Prizren prinos je bio vi&scaron;i oko 9% u 2030. godini i nepromenjen u 2050. godini. Uvećanje norme navodnjavanja je bilo veoma značajno na većini lokaliteta od 20% do 30% sa maksimumom u Požegi do 45% u 2030. i 84% u 2050. godini. Lokalitet Požega imao je zemlji&scaron;te tipa ilovasti fluvisol i izmeren visok procenat peska, iznad 50% u svom mehaničkom sastavu, &scaron;to je uslovilo i veću propusnost vode, njeno kraće zadržavanje u profilu zemlji&scaron;ta i potrebu za većom količinom vode u navodnjavanju. Simulacije prinosa soje odmah su urađene u uslovima navodnjavanja od 50% dostupne vode biljci, jer je opcija u uslovima bez navodnjavanja davala jako niske prinose, a opcija 50% dostupne vode je davala takve norme navodnjavanja koje su bile slične u na&scaron;im uslovima na Institutu za ratarstvo i povrtarstvoPri takvoj opciji navodnjavanja u svim lokalitetima norma navodnjavanja je u budućim uslovima veoma značajno rasla od 10 do 40% u 2030. godini i od 13 do 110% u 2050. godini, a rezultati relativne promene prinosa ukazivali su na veoma značajno povećanje prinosa u budućim&nbsp;uslovima.</p> / <p>DSSAT 4.0 is a crop model commonly used to quantify the climate change impact on agriculture production. The model predictions are very important for long term planning in agriculture to keep high and stable yield production. At the first, the climate was analysed for 1971-2000 period, 2030 and 2050 year. After these analyses the crop model was run. Crop model is based on interaction between climate, soil and plant. Simulations were predicted the yield and dynamic in vegetation for 2030 and 2050 climate conditions. As input parameters were used observed daily weather data from eleven weather stations for 1971-2000 period. For 2030 and 2050, the data were used from global climatology models ECHAM5, HadCM3 and NCAR-PCM for two scenarios A1B and A2. Before crop simulations, the out results from global climatology models had to be regionalised and downscaled with Met &amp; Roll weather generator. The soil input data were assumed from Agency for Environmental Safety from Belgrade. The data were consist of mechanical and chemical characteristics of soil which were chosen near the weather station. The crop input data were collected from the literature and personal communication of Institute of Field and Vegetable Crops and their long term period experiments. A current and future agroclimatic indices were calculated with Agriclim model. As a crop model, DSSAT v. 4.2. was chosen for crop simulations of major field crops: winter wheat, maize and soybean.<br />The results of climate shown that the air temperature should be higher in all vegetation phases, and precipitation should be higher during winter months, lower for 10 mm in spring and significantly lower in summer months June- July-August.<br />In 2030 and 2050 year (CO2=330 ppm) simulations shown that winter wheat yield might be the same as in 1971-2000 period in most locations except in Krusevac, Sombor and Vranje where yield might be lower for 12% in 2030 year and lower for 11% in 2050 year. It is a consequence of expected higher precipitation and higher air temperatures during winter period, less frosty and frozen days, higher precipitation during spring, which is a critical period for winter wheat production. It was analysed the dinamyc in vegetation in future<br />9<br />conditions. The results showed the shorter vegetation, less number of days from seeding to anthesis and seeding to maturity. These changes in vegetation duration were caused by expected higher air temperatures and higher effective temperatures.<br />The yield results were also analysed for expected conditions under future CO2 concentration from IPCC report 2007, and shown that winter wheat yields were not changed for most locations except in Krusevac and Sombor in 2030 and 2050 year.<br />The maize yield results for 2030 and 2050 under CO2 concentration of 330 ppm shown a significant decrease in yield in non irrigated conditiond and irrigated conditions with 180 mm water added per vegetation season. Also, the results given under expected CO2 concentration from IPCC Report 2007, shown great decrease in 2030 and 2050 and lower yield than under CO2 was set on 330 ppm. The significant decrease in yield was caused by expected higher temperatures in JJA period, higher physiologicaly stress caused by more days with extreme high temperatures (summer and tropical days) and very significant decrease in precipitation during JJA period. The results showed the shorter vegetation, less number of days from seeding to anthesis and seeding to maturity. These changes in vegetation duration were caused by expected higher air temperatures and higher effective temperatures.<br />The soybean yield analyses for 2030 and 2050 under CO2 concentration of 330 ppm shown no changes in yield for Cuprija, Nis, Vranje and Prizren, a little higher to 10% in Kraljevo, Krusevac, Novi Sad, Sombor, Zajecar and up to 24% higher in Dimitrovgrad and Pozega. In 2030 and 2050 under future CO2 concentrations from IPCC Report 2007, it is expected a significantly higher yield in all locations especially for Dimitrovgrad and Pozega, where the air temperatures were lowest in AMJ and JJA period. The results showed the shorter vegetation in soybean production, less number of days from seeding to anthesis and seeding to maturity. These changes in vegetation duration were caused by expected higher air temperatures and higher effective temperatures. After all simulations for winter wheat, maize and soybean, it is concluded that maize production need some adaptation measures for future conditions. As an adaptation measure it were chosen two measures: the shift in sowing date and irrigation quantity. The adaptation in sowing date was set for maize under non irrigated conditions, to analyse only the time of sowing not irrigation. The sowing date was set 15 days earlier, on the 5th of April. The yield results shown less decrease than results given at usual sowing date (20th of April), but in all locations the predicted yield decreased except in DM, VR and PR where the yield shown significant increase in a comparison with 1971-2000 yield. The change in irrigation quantity was more efficient for yield. It was done for maize production and soybean, because winter wheat irrigation was estimated as non economic. The irrigation method was set on 50% available water for plant. The maize yield was stable in Ćuprija, Kru&scaron;evac, Kraljevo, Ni&scaron;, Novi Sad, Sombor, Vranje, Zaječar in 2030 and 2050 year except in Kraljevo where the yield decreased up to 17% in 2050 year. In Dimitrovgrad, Požega and Prizren the yield was higher for 9% in 2030 year and not chaged in 2050 year. The water requirements had significantly higher values than in 1971-2000 period up to 20-30% in 2030 year with maximum in Požega up t 45% in 2030 year and 84% in 2050 year. The location Požega has soil with a high percent of sand in structure, above 50%, what caused quick water filtration and more water in irrigation. The soybean simulations were done in irrigation option of 50% available water at the begining, because the non irrigated method did not gave the satisfied yield results in crop model. The 50% irrigation method gave adequate yield and water requirements as in experiments on Institute. The water requirements had significantly higher values in 2030 year from 10-40% and from 13% to 110% in 2050 year than in 1971-2000 period.<br />Key words: climate change, CO2 fertilization, DSSAT v. 4.2. crop model, effective irrigation, maize yield, soybean yield, vegetation, winter wheat yield.</p>

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2017-10-16T11:54:44Z No. of bitstreams: 1 Bruna Treviso Cenci_.pdf: 1353743 bytes, checksum: 8f26b4c7d6c7b81666f8667d019dcdad (MD5) / Made available in DSpace on 2017-10-16T11:54:44Z (GMT). No. of bitstreams: 1 Bruna Treviso Cenci_.pdf: 1353743 bytes, checksum: 8f26b4c7d6c7b81666f8667d019dcdad (MD5) Previous issue date: 2017-07-24 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / O aumento das concentrações de CO2 atmosférico no último século deve impactar a produtividade primária dos ecossistemas. Esse efeito pode ser direto e positivo, devido a um mecanismo de fertilização, ou de modo indireto (positivo ou negativo) através de mudanças climáticas. Evidências sobre variação no balanço de carbono de florestas nas últimas décadas indicam respostas neutras em regiões boreais, positivas em regiões temperadas e negativas nos trópicos. Especificamente para florestas subtropicais há pouca evidência acerca de como a produtividade primária responde a esses fatores de mudança global. Nesse trabalho, investigamos como a produtividade primária de uma conífera arbórea dominante em florestas subtropicais úmidas do SE da América do Sul (Araucaria angustifolia) tem sido afetada ao longo do último século pelas concentrações de CO2 e consequentes alterações climáticas. Para uma população dessa espécie, testamos a validade das seguintes hipóteses: (i) o incremento de CO2 atmosférico afeta a taxa de fixação de carbono indiretamente, através do impacto do aquecimento global nos regimes regionais de temperatura e precipitação; e (ii) além desse efeito indireto, o incremento de CO2 afeta diretamente a taxa de fixação de carbono através de um mecanismo de fertilização. Para uma amostra inicial de 25 árvores de A. angustifolia de 0,33 ha de floresta subtropical madura no sul do Brasil, estimamos séries de incremento anual de carbono no lenho de 14 árvores, a partir de séries dendrocronológicas codatadas de largura de aneis (de um estudo preexistente) e de densidade de aneis (por densitometria de Raios X); e equações hipsométrica (ajustada à população local) e volumétrica (geral para a espécie). As séries individuais foram combinadas numa série média de índices de incremento de carbono (vetor I), filtrando previamente tendências ontogenéticas (pela Curva Regional de Padronização) e autocorrelação temporal (por modelos autoregressivos). Comparando I à séries regionais de temperatura média e precipitação total (estimativas do CRU TS4), através de Função de Correlação, selecionamos variáveis climáticas relacionadas à fixação de carbono (matrizes P e T). Dados instrumentais de concentração de carbono atmosférico (NOAA EARL) e estimativas de temperatura global (CRU TEM4) compuseram as matrizes C e A, respectivamente. Finalmente, a validade dos modelos causais descrevendo as relações entre as matrizes I, T, P, A e C segundo as diferentes hipóteses de estudo, foi testada por Análise de Caminhos. A cronologia de índices residuais de incremento de carbono obtida cobriu o período 1890 a 2014, com médias de rbar = 0,27 e EPS = 0,77. Nas análises subsequentes consideramos o período de 1901 a 2008 (período comum com as séries climáticas). Ambos modelos não foram rejeitados na Análise de Caminhos (P > 0,1), sendo o modelo que representa a hipótese i considerado mais plausível pelo maior p-valor para a estatística C de Fisher (Fisher-C = 9,25, gl = 10, P = 0,508). Nesse modelo, o aquecimento global decorrente da elevação do CO2 afeta negativamente o incremento de carbono em A. angustifolia através da elevação da temperatura de maio prévio na região. Além deste fator climático, as precipitações de março e junho prévios afetam a fixação de carbono de modo positivo, porém ambas não são influenciadas pelo CO2 através do aquecimento global. Em conjunto, as variáveis climáticas explicaram 19% da variação temporal do incremento de carbono das árvores. Esses resultados demonstram que, apesar do conhecido impacto positivo do aumento do CO2 na eficiência do uso água nessa espécie (e sítio) isso não se traduz em maior produtividade primária, possivelmente pelo carácter ombrófilo do clima regional. Por outro lado, a mudança para outonos com temperatura mais elevadas tem resultado em menor produtividade primária de A. angustifolia ao longo do último século. Sendo esta espécie dominante e com papel chave na estrutura trófica, este efeito negativo da mudança climática na sua produtividade, possivelmente, pode impactar indiretamente a estrutura e o funcionamento dos ecossistemas em que insere. / The increase in the concentrations of atmospheric CO2 in the last century must impact ecosystems primary productivity. This effect may be direct and positive, due to a fertilization mechanism, or indirect (positive or negative) through climate changes. Evidences on the variation of carbon balance in forests in the last decades indicate neutral responses in boreal regions, positive in temperate regions and negative in the tropics. There is little evidence about how primary productivity responds to these global changing factors in subtropical forests. In this study, we investigate how the primary productivity of a dominant conifer in subtropical moist forests of the Southeast region of South America (Araucaria angustifolia) has been affected throughout the last century by elevated CO2 concentrations and consequent climate alterations. For a population of this species, we have tested the validity of the following hypothesis: (i) the increase of atmospheric CO2 indirectly affects the rate of carbon fixation, through the impact of global warming in the local temperature and rainfall regimes; and (ii) besides this indirect effect, the increment in CO2 directly affects the rate of carbon fixation through a fertilization mechanism. In an initial sample of 25 A. angustifolia trees from 0,33 ha of mature subtropical forest in the south of Brazil, we estimated annual series of wood carbon content for 14 trees using series of dendrochronologically dated growth-ring widths (from a preexisting study) and growth-ring densities (by X ray densitometry), and hypsometric (adjusted to local population) and volumetric (general for the species) equations. The individual series were combined in an average index series of carbon increment (I vector), previously removing ontogenetic tendencies (through Regional Curve Standardization) and time autocorrelation (by autoregressive models). By comparing I to regional series of mean temperature and total rainfall (estimations of CRU TS4) through a Correlation Function, we selected several climatic variables related to carbon fixation (P and T matrices). Instrumental data of atmospheric C concentration (NOAA EARL) and estimations of global temperature (CRU TEM4) composed matrices C and A, respectively. Finally, the validity of causal models describing the relations among matrices I, T, P, A e C according to the different hypothesis of the study, was tested through Path Analysis. The resulting chronology of residual indexes of carbon increment comprehended the period of 1890 to 2014, with averages of rbar = 0,27 and EPS = 0,77. In the subsequent analysis, we considered the period of 1901 to 2008 (common period with the climate series). Both models were not rejected in the Path Analysis (P > 0,1), and the model which represents the i hypothesis was considered the most plausible by the greater p-value for the Fisher’s C-statistic (Fisher-C = 9.25, gl =10, P = 0.508). In this model, global warmth comes from the elevation of CO2 which negatively affects the increase in carbon content in A. angustifolia through regional temperature elevation (in previous) may. Besides this climatic factor, rainfalls in previous march and june affected carbon fixation in a positive way, although both are not influenced by CO2 through global warming. In summary, climatic variables explained 19% of temporal variation of carbon increase in the trees. These results demonstrate that, despite the known positive impact of CO2 in water use efficiency in this species (and site), this does not translate into a greater primary productivity, possibly by the ombrophilous character of the regional climate. On the other hand, the change into autumns with higher temperatures has resulted in lower primary productivity of A. angustifolia throughout the last century. As this is the dominant species and plays a key role in the trophic structure, this negative effect of the climatic change in its productivity may, possibly, indirectly impact the structure and the operation of the ecosystems in which it is inserted.