Author Correction: Biotic soil-plant interaction processes explain most of hysteretic soil CO2 efflux response to temperature in cross-factorial mesocosm experiment.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Biotic soil-plant interaction processes explain most of hysteric soil CO2 efflux response to temperature in cross-factorial mesocosm experiment.

Ecosystem carbon flux partitioning is strongly influenced by poorly constrained soil CO2 efflux (Fsoil). Simple model applications (Arrhenius and Q10) do not account for observed diel hysteresis between Fsoil and soil temperature. How this hysteresis emerges and how it will respond to variation in vegetation or soil moisture remains unknown. We used an ecosystem-level experimental system to independently control potential abiotic and biotic drivers of the Fsoil-T hysteresis. We hypothesized a principally biological cause for the hysteresis. Alternatively, Fsoil hysteresis is primarily driven by thermal convection through the soil profile. We conducted experiments under normal, fluctuating diurnal soil temperatures and under conditions where we held soil temperature near constant. We found (i) significant and nearly equal amplitudes of hysteresis regardless of soil temperature regime, and (ii) the amplitude of hysteresis was most closely tied to baseline rates of Fsoil, which were mostly driven by photosynthetic rates. Together, these findings suggest a more biologically-driven mechanism associated with photosynthate transport in yielding the observed patterns of soil CO2 efflux being out of sync with soil temperature. These findings should be considered on future partitioning models of ecosystem respiration.

Identificación de factores de confusión en el estudio de la relación cáncer colorrectal-dieta / Identifying confounding factors in studies of therelationship between colorectal cancer and diet

Introducción. La dieta se reconoce como segunda causa evitable relacionada con el desarrollo de cáncer. No obstante, dado su naturaleza multicausal, al estudiar la relación cáncer-dieta deben considerarse otros factores con potencial efecto confusor para evitar sesgos en estimaciones de riesgo. Objetivos. a) Identificar el efecto confundente del nivel de actividad física, hábito de fumar y nivel socioeconómico en la relación cáncer colorrectal (CCR) y dieta; b) Valorar el riesgo de factores alimentarios asociados a CCR, considerando las variables confundentes identificadas. Metodología. Se condujo un estudio caso-control (n=319; 102 casos de CCR, 217 controles) en Córdoba, Argentina (2006-2011). Se realizó un análisis bivariado entre variables alimentarias de interés y presencia de CCR, estimando ORs como medida de asociación. Luego, mediante análisis de Mantel-Haenszel, se estratificó por potenciales variables confundentes. Finalmente, se construyeron modelos de regresión logística múltiple, incluyendo las confundentes. Resultados. Se verificó efecto confusor del nivel socioeconómico en relación al consumo de carnes rojas cocidas, fibra y etanol, y de la actividad física en cuanto al consumo de fibra alimentaria. Controlando por dichos efectos, no se encontró asociación (OR 0,71; IC95 por ciento 0,31-1,62) entre la ingesta de fibra y la patología, y se observó un efecto promotor (OR 1,75; IC95 por ciento 0,95- 2,60) del nivel socioeconómico bajo y de la ingesta energética diaria (OR 1,0003; IC95 por ciento 1,00008-1,0006). Conclusión. Se reconoce el nivel socioeconómico y la actividad física como potenciales variables confusoras en el estudio de la relación CCR y alimentación en Argentina. Se recomienda considerarlas como variables de ajuste al realizar análisis de riesgos alimentarios.

Introduction. Diet is the second preventable cause related to the development of cancer. Given its multi-causal nature, in studying the relationship between cancer and diet, other factors with potential confounding effect must be considered to avoid bias in risk estimates. Objectives: a) Identifying the confounding effect of physical activity level, smoking habits and socioeconomic status in the relationship between colorectal cancer and cooked red meat, fiber and alcohol intake; b) Assessing the effect of dietary factors on the occurrence of colorectal cancer, considering the confounding variables identified. Methods. A case-control study was conducted (102 cases with colorectal cancer and 217 controls) in Cordoba, Argentina, over 2006-2011. A bivariate analysis, between food variables and the presence of colorectal cancer, and a Mantel-Heanzel analysis, stratifying by the potential confounders, were conducted. Finally, multiple logistic regression models were constructed, including the confounding variables. Results. Confounding effect of the socioeconomic status related to cooked red meat, fiber and alcohol intake, and physical activity level was verified. There was no association between fiber intake and colorectal cancer (OR 0,71; IC95 percent 0,31-1,62), while a promoting effect of low socioeconomic status (OR 1,75; IC95 percent 0,95-2,60), and daily energy intake (OR 1,0003; IC95 percent 1,00008-1,0006) were found. Conclusion. It is recommended to consider socioeconomic status and physical activity as adjusted factors when conducting food risk analysis in the study of the relationship between colorectal cancer and diet in Argentina.