N-15 in symbiotic fungi and plants estimates nitrogen and carbon flux rates in Arctic tundra
Hobbie, John E.
Hobbie, Erik A.
MetadataShow full item record
KeywordAlaska; Arctic tundra; Carbon flux; Mycorrhizae; N-15; Nitrogen-limited ecosystems; Plant nitrogen; Soil nitrogen; Plant–fungal symbioses; Soil–microbe–root relationships
When soil nitrogen is in short supply, most terrestrial plants form symbioses with fungi (mycorrhizae): hyphae take up soil nitrogen, transport it into plant roots, and receive plant sugars in return. In ecosystems, the transfers within the pathway fractionate nitrogen isotopes so that the natural abundance of N-15 in fungi differs from that in their host plants by as much as 12‰. Here we present a new method to quantify carbon and nitrogen fluxes in the symbiosis based on the fractionation against N-15 during transfer of nitrogen from fungi to plant roots. We tested this method, which is based on the mass balance of N-15, with data from arctic Alaska where the nitrogen cycle is well studied. Mycorrhizal fungi provided 61–86% of the nitrogen in plants; plants provided 8–17% of their photosynthetic carbon to the fungi for growth and respiration. This method of analysis avoids the disturbance of the soil–microbe–root relationship caused by collecting samples, mixing the soil, or changing substrate concentrations. This analytical technique also can be applied to other nitrogen-limited ecosystems, such as many temperate and boreal forests, to quantify the importance for terrestrial carbon and nitrogen cycling of nutrient transfers mediated by mycorrhizae at the plant–soil interface.
Author Posting. © Ecological Society of America, 2006. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 87 (2006): 816-822.
Showing items related by title, author, creator and subject.
Mycorrhizal fungi supply nitrogen to host plants in Arctic tundra and boreal forests : 15N is the key signal Hobbie, John E.; Hobbie, Erik A.; Drossman, Howard; Conte, Maureen H.; Weber, John C.; Shamhart, Julee; Weinrobe, Melissa (NRC Research Press, 2009-02-03)Symbiotic fungi’s role in providing nitrogen to host plants is well-studied in tundra at Toolik Lake, Alaska, but little-studied in the adjoining boreal forest ecosystem. Along a 570 km north–south transect from the Yukon ...
Incident radiation and the allocation of nitrogen within Arctic plant canopies : implications for predicting gross primary productivity Street, Lorna E.; Shaver, Gaius R.; Rastetter, Edward B.; van Wijk, Mark T.; Kaye, Brooke A.; Williams, Mathew (2012-01)Arctic vegetation is characterized by high spatial variability in plant functional type (PFT) composition and gross primary productivity (P). Despite this variability, the two main drivers of P in sub-Arctic tundra are ...
Depleted 15N in hydrolysable-N of arctic soils and its implication for mycorrhizal fungi–plant interaction Yano, Yuriko; Shaver, Gaius R.; Giblin, Anne E.; Rastetter, Edward B. (2009-08)Uptake of nitrogen (N) via root-mycorrhizal associations accounts for a significant portion of total N supply to many vascular plants. Using stable isotope ratios (δ15N) and the mass balance among N pools of plants, ...