Effects of warming, ozone exposure and nitrogen addition on soil microbial profiles in rhizosphere area of Scots pine (Pinus sylvesteris) seedlings
Year: 2015
Type: dissertation
Abstract: Increasing atmospheric temperature, tropospheric ozone (O3) concentration and nitrogen (N) deposition in the boreal forests are effecting the forest ecology.In this work, the effect of the above three factors, alone and in combination, on the below-ground microbial profiles in the Scots pine (Pinus sylvestris) rhizosphere have been studied.The experiment was set up in a field where the seedlings were placed in eight exposure plots.Half of the plots were exposed to elevated ozone concentrations (1.5x ambient O3) using the open air fumigation systems, and the rest of the plots were ambient air plots.These plots were further divided into subplots for warming treatments: in each plot one subplot was kept at elevated temperature using infrared heaters (air temperature elevation c. +1°C, soil temperature elevation c. 0.8°C) and other subplots were kept at ambient temperature.Half of the trees in each subplot received nitrogen fertilization (N dose 120 kg/ha/a in 2011 and 2013), while rest were grown at prevailing soil N level.The microbial profiles were studied using phospholipid derived fatty acids (PLFAs) from soil samples collected in autumn 2013.The main microbial groups in the rhizosphere soil were gram-positive, gram-negative bacteria, Fungi(AMF-) (all fungi except AMF) and Fungi(AMF+) (only AMF).The results revealed that warming increased while ozone exposure decreased fungi(AMF-) relative abundance.Relative abundance of gramnegative bacteria decreased while that of fungi(AMF-) increased in response to increased nitrogen availability.Ozone exposure and warming showed significant interactive effect on fungi(AMF-) whereby they warming partly compensated for the effects of ozone.Results obtained in this experiment show that the below-ground microbial profiles are sensitive to the futuristic climatic conditions especially fungi; which it may effect the soil nutrient cycle.
Author: Muhammad Usman Rasheed
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDGs: Life on land, Climate action
Open Access status: green
Funder: Itä-Suomen Yliopisto
Award: G418833491
OpenAlex ID: W3096462402