Determinants of above-ground carbon stocks and productivity in secondary forests along a 3000-m elevation gradient in the Ecuadorian Andes

Background: Secondary montane forests, covering 30% of forested lands in the Andes, play a crucial role in mitigating the impact of carbon release. However, the mechanisms responsible for carbon sequestration in the above-ground biomass of these forests are not well quantified. Aims: Understanding the determinants of above-ground carbon (AGC) dynamics in secondary forests along a 3000-m elevational gradient in the Andes to assess their mitigation potential. Methods: We assessed how abiotic and biotic conditions and past human disturbances were related to forest structure and composition, AGC stocks and productivity within sixteen 0.36-ha plots established in secondary forest stands of 30–35 years of age. Results: Structural equation models revealed that changes in temperature conditions along the elevation gradient shaped leaf functional composition, which in turn controlled AGC dynamics. Productivity and temperature decreased with increasing elevation and decreased tree community leaf area. Disturbance legacy (Tree mortality) increased with competitive thinning and low soil fertility. Conclusions: We show that temperature drives AGC dynamics by changing the functional trait composition. This highlights the importance of preserving these forests along elevation gradients and implies potentially strong future changes due to global warming.</p

Flexible automatic algorithm for comet assay analysis

The comet assay is a commonly used technique in molecular and cell biology fields, for studies in which the DNA damage of a cell is measured. For instance, it is useful to analyze whenever a carcinogenic cell is affected by chemical agents, helping with oncology research. Traditionally, in order to evaluate the damage of a cell, an expert observes the morphology and the intensity (brightness) of the resulting comet. However, taking into account that a large number of images have to be analyzed, this task may demand a lot of time to be done manually. In recent years, the comet assay analysis has been implemented semi-automatically and automatically with the rise of new image processing algorithms. Although these new algorithms reduce the time invested in the image analysis, some problems in comet identification and accurate measure of their components need to be improved. This project aimed to develop an algorithm and an interface, named CometLab, for flexible automatic comet segmentation. Its performance was assessed with a set of images and compared against an open source, available software called OpenComet. It was found that only 1 of the 15 features that were extracted by both algorithms was not statistically correlated (head diameter), meaning that the designed application is suitable; therefore, this research helped to obtain information about the performance of CometLab in comparison to OpenComet, which serves as setpoint for future works in which it would be possible to decide which algorithm is better. © SPIE. Downloading of the abstract is permitted for personal use only