Project description:Analysis of microbial community composition in arctic tundra and boreal forest soils using serial analysis of ribosomal sequence tags (SARST). Keywords: other
Project description:Soil microbial community is a complex blackbox that requires a multi-conceptual approach (Hultman et al., 2015; Bastida et al., 2016). Most methods focus on evaluating total microbial community and fail to determine its active fraction (Blagodatskaya & Kuzyakov 2013). This issue has ecological consequences since the behavior of the active community is more important (or even essential) and can be different to that of the total community. The sensitivity of the active microbial community can be considered as a biological mechanism that regulates the functional responses of soil against direct (i.e. forest management) and indirect (i.e. climate change) human-induced alterations. Indeed, it has been highglihted that the diversity of the active community (analyzed by metaproteomics) is more connected to soil functionality than the that of the total community (analyzed by 16S rRNA gene and ITS sequencing) (Bastida et al., 2016). Recently, the increasing application of soil metaproteomics is providing unprecedented, in-depth characterisation of the composition and functionality of active microbial communities and overall, allowing deeper insights into terrestrial microbial ecology (Chourey et al., 2012; Bastida et al., 2015, 2016; Keiblinger et al., 2016). Here, we predict the responsiveness of the soil microbial community to forest management in a climate change scenario. Particularly, we aim: i) to evaluate the impacts of 6-years of induced drought on the diversity, biomass and activity of the microbial community in a semiarid forest ecocosystem; and ii) to discriminate if forest management (thinning) influences the resistance of the microbial community against induced drought. Furthermore, we aim to ascertain if the functional diversity of each phylum is a trait that can be used to predict changes in microbial abundance and ecosystem functioning.
Project description:Climate change forecasts increase the susceptibility of forest due to longer drier seasons. The adaptive management protocols have highlighted the reduction of the forest densification to improve their vulnerability to extreme climate events (i.g. drought). One of this sensitive woody species to climate change is the Abies pinsapo, a relic conifer tree endemic from the southern Spain. Previous works have shown changes in their trends because of the climate change action, being carried out experimental thinning management in their lowest distribution limit, in Sierra de las Nieves Natural Park (Malaga). Our objective is to evaluate the water improvements of thinned trees in terms of light availability by means of a shading treatment in those thinned trees. To do that we have evaluated the synergic effect of ecophysiology, metabolomics and transcriptomics in control, thinning and thinning+shading plots in wet and dry seasons for two years. The results showed strong differences between summer and spring seasons at the three studied levels. The water deficit shows a greater influence than light exposure in the ecophysiology and metabolomics tree response. And the transcriptomics suggested an improvement of thinned trees when light exposure was reduced. Our results support the necessity of adaptive forest management in order to improve the conservation status of A. pinsapo forest. The combination of different levels of tree response is paramount to understand and predict the tree physiology under water and light stress conditions.
Project description:Anthropogenic nitrogen (N) deposition may affect soil organic carbon (SOC) decomposition, thus affecting the global terrestrial carbon (C) cycle. However, it remains unclear how the level of N deposition affects SOC decomposition by regulating microbial community composition and function, especially C-cycling functional genes structure. We investigated the effects of short-term N addition on soil microbial C-cycling functional gene composition, SOC-degrading enzyme activities, and CO2 emission in a 5-year field experiment established in an artificial Pinus tabulaeformis forest on the Loess Plateau, China.