Principal investigator: Mgr. Filip Oulehle, Ph.D.
(Co)investigator from the Department: Karolina Tahovská
Duration: 2014 - 2016

Project goals: 
1) assessment of the shift in the relative balance of soil N and C accumulation, versus losses in either organic or inorganic forms, 2) description of the change in internal soil processes and decomposer composition and its link to the change in soil chemistry, 3) biogeochemical modelling

Project description: 
Nitrogen (N) and sulphur (S) deposition are important drivers of the terrestrial carbon (C) and N cycling. In the past 25 years deposition of S has decreased by >80%, whereas reduction in N deposition was much smaller. It is thus possible that recent measurements of C and N fluxes might not be representative of systems in long-term balance with climatic conditions. A set of replicated acidity/N availability experiments in beech and spruce forests will be undertaken in an area of formerly high S/N deposition to understand the combined effects of S and N deposition on C and N cycling in forest soils. In each experiment, we will measure the effects of soil alteration on: A) losses of C and N in gaseous and dissolved forms, B) soil microbial community composition and C) key ecosystem processes, such as the transformation of C and N between organic and inorganic forms, using a combination of cutting edge isotopic tracing and molecular techniques, enzyme measurements and ecosystem modelling.

(Spolu)řešitel na KBE: Jaroslav Vrba
Poskytovatel: Grantová agentura České republiky
Doba trvání: 2015 - 2017

Cíle projektu: 
Hlavními cíli projektu je zpracování vzorků zooplanktonu a analýzy dosud nevyhodnocených datových řad o stratifikaci, chemismu a planktonu, získaných během ~60 let dlouhodobého ekologického výzkumu Slapské nádrže.

Popis projektu: 
Projekt je zaměřen na dosud neprobádané dědictví české nádržové limnologie: téměř 60-letá data o stratifikaci, chemismu a planktonu Slapské nádrže. Jejich zpracování umožní popsat změny v druhovém složení, fenologii, množství biomasy a velikostní struktuře klanonožců a perlooček a určit druhově specifické odpovědi na antropogenní a klimatické změny v celém povodí Slapské nádrže od výstavby Vltavské kaskády. Výstupy projektu prohloubí obecné porozumění řídícím vlivům v ekologii plankonu, hlavně vlivům klimatu, hydrologie a teplotní stratifikace, hydrodynamiky nádrže a zatížení živinami na strukturu a sezonní vývoj planktonních společenstev. Získané závěry budou použitelné zejména pro morfologicky podobné nádrže mírného pásma.

Principal investigator: prof. RNDr. Karel Šimek, CSc.
(Co)investigator from the Department: Karel Šimek
Duration: 2013 - 2017

Project goals: 

• To measure growth potential of relevant isolated strains, or genus-like taxa of the target bacteria by exploiting specifically designed in situ experiments in several habitats during different phases of plankton succession.
• To establish the nutritive value of the representative strains for natural HNF communities when these bacteria are fed as the dominant food source; detecting of HNF growth parameters and biomass yield related to a particular prey item.
• To characterize intra-genus and intra-species diversity in ecophysiological and genomic traits of the target bacteria, based on experimental tests (growth and prey quality parameters) and genome analysis of closely related bacteria.
• To reveal if rate-specific differences in carbon-flow to higher trophic levels, which are expected between Limnohabitans and Polynucleobacter C-subcluster, can be linked to qualitative (e.g., gene content) or quantitative (e.g. genome size, gene families, functional groups of genes) genome traits.
• To suggest important features of life strategies of the target bacterial groups that will contribute to refinements of life strategy concepts applicable for representative freshwater bacteria.

Project description: 
We propose investigations of life strategies related to genomic and ecophysiological traits of representative strains of the key groups of freshwater Betaproteobacteria, i.e. the genera Limnohabitans and Polynucleobacter, with contrasting lifestyles and frequently also different habitat preferences. We hypothesize that strains affiliated with these abundant groups differ in growth potential and grazing-induced mortality in situ, thus modulating the role of the groups in carbon flow to higher trophic levels. Notably, a large collection of representative strains from both groups is available that facilitates examination of diversity in ecophysiologic and genomic traits of these bacteria. Specific in situ experimental designs are proposed for testing of ecophysiological characteristics of the bacteria and estimating of their taxon-specific roles in carbon transfer to bacterivorous flagellates in five different habitats. Important new insights into distinct bacterial lifestyles are assumed, including implications for refinement of existing concepts of bacterial life strategies.

(Co)investigator from the Department: Eva Kaštovská
Funding provider: Grantová agentura České republiky
Duration: 2016 -2018

Project goals: 
The overarching aim of the project is to determine the mechanisms relating plant C:N stoichiometry to plant and microbial activities in the rhizosphere and how shifts in plant C:N ratios and related physiological changes will impact C and N cycling in soil.

Project description: 
We want to study the connection between The C:N stoichiometry of plant tissue and root-released compounds, and their effects on rhizosphere microbial activity and soil C and N sequestration. The C:N stoichiometry of root exudation was recognized as the important factor constraining microbial performance in soil. Likely, the C:N ratio of root exudation is closely related to root C:N and the C:N ratio and composition of the plant metabolome. However, neither of these relations nor their effects on soil microbial activity have been directly studied yet. We will study these relations for two plant species, conservative versus competitive, using a manipulative mesocosm experiment. We will shift plant C:N stoichiometry through foliar N application thus maintaining the same initial conditions of N availability in the soil with the only input of additional N via the plant. Then we will determine the relations between increased plant N and other plant functional traits, and soil C and N cycling using biochemical and analytical methods including stable isotope probing and plant metabolomics.