Carbon dioxide fluxes over an ancient broadleaved deciduous woodland in southern England

We present results from a study of canopy-atmosphere fluxes of carbon dioxide from 2007 to 2009 above a site in Wytham Woods, an ancient temperate broadleaved deciduous forest in southern England. Gap-filled net ecosystem exchange (NEE) data were partitioned into gross primary productivity (GPP) and ecosystem respiration (R(e)) and analysed on daily, monthly and annual timescales. Over the continuous 24 month study period annual GPP was estimated to be 21.1Mg C ha(-1) yr(-1) and R(e) to be 19.8Mg C ha(-1) yr(-1); net ecosystem productivity (NEP) was 1.2Mg C ha(-1) yr(-1). These estimates were compared with independent bottom-up estimates derived from net primary productivity (NPP) and flux chamber measurements recorded at a plot within the flux footprint in 2008 (GPP = 26.5 +/- 6.8Mg C ha(-1) yr(-1), R(e) = 24.8 +/- 6.8Mg C ha(-1) yr(-1), biomass increment = similar to 1.7Mg C ha(-1) yr(-1)). Over the two years the difference in seasonal NEP was predominantly caused by changes in ecosystem respiration, whereas GPP remained similar for equivalent months in different years. Although solar radiation was the largest influence on daily values of CO(2) fluxes (R(2) = 0.53 for the summer months for a linear regression), variation in R(e) appeared to be driven by temperature. Our findings suggest that this ancient woodland site is currently a substantial sink for carbon, resulting from continued growth that is probably a legacy of past management practices abandoned over 40 years ago. Our GPP and R(e) values are generally higher than other broadleaved temperate deciduous woodlands and may represent the influence of the UK's maritime climate, or the particular species composition of this site. The carbon sink value of Wytham Woods supports the protection and management of temperate deciduous woodlands (including those managed for conservation rather than silvicultural objectives) as a strategy to mitigate atmospheric carbon dioxide increases

Fosfitos para o controle de podridões pós-colheita em maçãs ‘Fuji’ durante o armazenamento refrigerado Use of phosphites for rot control during cold storage of ‘Fuji’ apples

Foi conduzido um experimento com o objetivo de avaliar o efeito da aplicação de adubos foliares contendo fosfitos de potássio e fosfitos de cálcio mais boro sobre o controle de podridões em maçãs ‘Fuji’ durante a frigoconservação. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições de 25 frutos. Foram realizadas quatro lesões distribuídas de forma eqüidistante na região equatorial dos frutos, com 3mm de diâmetro e 5mm de profundidade. Os frutos foram submersos em uma solução com suspensão de esporos, onde permaneceram por 20 segundos. Após, foram aplicados os tratamentos: 1 - Testemunha (água); 2 - Iprodione (75g 100L-1); 3 - cloreto de cálcio( CaCl2) a 2%; 4 - fosfito de potássio (250mL 100L-1) + CaCl2 (2%); 5 - fosfito de potássio (250mL 100L-1); 6 - fosfito de cálcio mais boro (300mL 100L-1); e 7 - fosfito de potássio (250mL 100L-1) na suspensão de esporos por uma hora. Os frutos foram armazenados em ambiente refrigerado à temperatura de 0&deg;C durante 14 dias. As avaliações foram realizadas na saída da câmara e aos 2, 4, 6 e 8 dias a 20&deg;C. Verificou-se que os frutos tratados com fosfito de potássio (250mL 100L-1) + CaCl2 (2%) apresentaram a menor incidência de podridões e o menor diâmetro de lesão. Esses resultados foram semelhantes aos obtidos com a aplicação do fungicida padrão Iprodione e superiores à aplicação de fosfito de potássio isoladamente. O uso de fosfito de cálcio mais boro não foi eficiente.<br>This experiment aimed to evaluate the effectiveness of potassium (K) phosphite and calcium (Ca) + borum (B) phosphite to control rot during cold storage of ‘Fuji’ apples. Four equidistant lesions were made in the central region of the fruits, measuring 5mm wide and 3mm deep. After the treatments, fruits were submerged for 20 seconds in a spore suspension, except for the last treatment, in wich the immersion lasted one hour. The treatments were as follow: 1. control (water); 2. fungicide Iprodione (75g 100L-1); 3. CaCl2 (2%); 4. potassium phosphite (250mL 100L-1) plus CaCl2 (2%); 5. potassium phosphite (250mL 100L-1); 6. Ca + B phosphite (300mL 100L-1); and 7. potassium phosphite (250mL 100L-1) in spore suspension for one hour. Fruits were refrigerated at 0&deg;C during 14 days and evaluated at removal from cold room and after 2, 4, 6 and 8 days at 20&deg;C. Fruits treated with potassium phosphite (250mL 100L-1) combined with CaCl2 (2%) had less decay and smallest lesion diammeter. These results were similar to those obtained with the fungicide Iprodione. Potassium phosphite alone was not as effective as in combination with CaCl2, and Ca + B phosphite was not effective to control apple rot