Author(s): Akshit Puri, Kiran Preet Padda, Chris P Chanway
Published in: Forest Ecology and Management (September 2018)
Evidence of endophytic diazotrophic bacteria in lodgepole pine and hybrid white spruce trees growing in soils with different nutrient statuses in the West Chilcotin region of British Columbia, Canada
Bacterial biofertilizers are regarded as a sustainable and environment-friendly way to support plant growth through various mechanisms, including biological nitrogen fixation. Biological nitrogen fixation is a process by which atmospheric N2 gas is converted into a plant-usable form (NH3) by certain bacteria. In natural ecosystems like boreal forests, such bacteria could be a potent source of nitrogen nutrition for trees growing on nutrient-poor soils. West Chilcotin is a remote region located in central-interior BC where cold climate and low annual precipitation have resulted in dry and weakly developed soils lacking essential plant nutrients. This region is commonly affected by disturbances like forest fires and timber harvesting, which has led to the gradual loss of vital nutrients from soils. Most common tree stands in this region are lodgepole pine and hybrid white spruce.
In this study, we observed that soils in this region lack essential plant nutrients and were particularly poor in nitrogen. Therefore, the ability of pine and spruce to grow on such nutrient-poor (nitrogen-limited) soils raises a crucial question regarding nitrogen sources for these trees. One of the sources that we evaluated in this study was biological nitrogen fixation by bacteria living inside the tissues of pine and spruce trees growing in this region. We successfully isolated 103 potential nitrogen-fixing bacteria from the tissues of these trees. Out of these 103 bacteria, we tested and identified 41 bacteria as prominent nitrogen-fixers. In future, such nitrogen-fixing bacteria could be inoculated into seedlings and planted at sites with limited soil nitrogen levels. Such bacteria may sustain the tree growth for years and could act as an environment-friendly and cost-effective solution to offset/reduce the need to periodically apply chemical fertilizers to forest stands.
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