Suitability and use of the 15N-isotope dilution method to estimate nitrogen fixation by actinorhizal shrubs

Busse, Matt D.

doi:10.1016/s0378-1127(99)00264-9

Cited by 41 publications

(42 citation statements)

References 32 publications

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“…Secondly, we did not simulate an understory in the Juniper site. The dominant understory species is bitterbrush (Pursia tridentata), a strong N 2 -fixer (Busse et al 2000). Contributions of inorganic N not accounted for in a juniper-dominated simulation may have contributed to our simulated underestimates of carbon pools and fluxes at this site.…”

Section: Gppmentioning

confidence: 95%

An analysis of soil respiration across northern hemisphere temperate ecosystems

et al. 2005

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Abstract. Over two-thirds of terrestrial carbon is stored belowground and a significant amount of atmospheric CO 2 is respired by roots and microbes in soils. For this analysis, soil respiration (Rs) data were assembled from 31 AmeriFlux and CarboEurope sites representing deciduous broadleaf, evergreen needleleaf, grasslands, mixed deciduous/evergreen and woodland/savanna ecosystem types.Lowest to highest rates of soil respiration averaged over the growing season were grassland and woodland/savanna < deciduous broadleaf forests < evergreen needleleaf, mixed deciduous/ evergreen forests with growing season soil respiration significantly different between forested and non-forested biomes (p < 0.001). Timing of peak respiration rates during the growing season varied from March/April in grasslands to July-September for all other biomes. Biomes with overall strongest relationship between soil respiration and soil temperature were from the deciduous and mixed forests (R 2 ‡ 0.65). Maximum soil respiration was weakly related to maximum fine root biomass (R 2 = 0.28) and positively related to the previous years' annual litterfall (R 2 = 0.46). Published rates of annual soil respiration were linearly related to LAI and fine root carbon (R 2 = 0.48, 0.47), as well as net primary production (NPP) (R 2 = 0.44). At 10 sites, maximum growing season Rs was weakly correlated with annual GPP estimated from eddy covariance towersites (R 2 = 0.29; p < 0.05), and annual soil respiration and total growing season Rs were not correlated with annual GPP (p > 0.1). Yet, previous studies indicate correlations on shorter time scales within site (e.g., weekly, monthly). Estimates of annual GPP from the Biome-BGC model were strongly correlated with observed annual estimates of soil respiration for six sites (R 2 = 0.84; p < 0.01). Correlations from observations of Rs with NPP, LAI, fine root biomass and litterfall relate above and belowground inputs to labile pools that are available for decomposition. Our results suggest that simple empirical relationships with temperature and/or moisture that may be robust at individual sites may not be adequate to characterize soil CO 2 effluxes across space and time, agreeing with other multi-site studies. Information is needed on the timing and phenological controls of substrate availability (e.g., fine roots, LAI) and inputs (e.g., root turnover, litterfall) to improve our ability to accurately quantify the relationships between soil CO 2 effluxes and carbon substrate storage.

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Section: Gppmentioning

confidence: 95%

An analysis of soil respiration across northern hemisphere temperate ecosystems

et al. 2005

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“…The quantity of N fixed by legumes (N fixed, g N m -2 ) was calculated as the following equation (Busse 2000):…”

Section: Sampling and Calculationsmentioning

confidence: 99%

Symbiotic nitrogen fixation by legumes in two Chinese grasslands estimated with the 15N dilution technique

Yang

Qiao

et al. 2011

Nutr Cycl Agroecosyst

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Symbiotic nitrogen (N) fixation by legumes was investigated using the 15 N dilution technique in two Chinese grasslands: one in the north-eastern Tibetan Plateau and the other in Inner Mongolia in China. A small amount (0.03 g N m -2 ) of 15 N labelled (NH 4 ) 2 SO 4 fertilizer was evenly distributed in two soils. One month after the 15 N addition, four legumes (Astragalus sp., Gueldenstaedtia diversifolia, Oxytropis ochrocephala and Trigonella ruthenica) in the alpine meadow and two legumes (Thermopsis lanceolata and Melissitus ruthenica) in the temperate steppe were collected. Several non-legume plant species were harvested as the reference. Above-ground biomass of legumes ranged from 8 to 24 g m -2 in the alpine meadow and from 11 to 35 g m -2 in the temperate steppe. The reference plants showed distinctly higher 15 N atom% excess than legumes (0.08% vs. 0.02% in the alpine meadow, 0.10% vs. 0.02% in the temperate steppe). The N derived from atmosphere (%Ndfa) ranged from 50 to 90% N in the alpine meadow, while it ranged from 85 to 92% in the temperate steppe. Based on the legume above-ground biomass, total symbiotic N 2 -fixation rate was estimated to be 1.00 g N m -2 year -1 in the alpine meadow and 1.15 g N m -2 year -1 in the temperate steppe. These N inputs by legumes can account for 9% of the gap between the N demand and the seasonal N release by mineralization in the alpine Kobresia grassland and 20% in the temperate Leymus grassland, respectively. Considering additional contribution of the root biomass, we suggest that biological N 2 -fixation by legumes plays an important role in the cycling of N in both Kobresia and Leymus grasslands on an annual scale.

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“…In the actinorhizal plant Ceanothus velutinus, Busse (2000) showed that the percentage of nitrogen fixed in root nodules exceeded 80% of the total nitrogen accumulated in the plants. Further, Wall (2000) reported that the annual amount of nitrogen (240-350 kg·ha −1 · year −1 ) fixed in Frankia-actinorhizal root nodules was similar to that in Rhizobium-legume root nodules.…”

Section: Influence Of Inoculation On Plant Growthmentioning

confidence: 99%

Nitrogen Fixation in Seabuckthorn (Hippophae rhamnoides L.) Root Nodules and Effect of Nitrate on Nitrogenase Activity

一幾¹,

喜則²,

亘³

et al. 2007

J. Japan. Soc. Hort. Sci.

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Seabuckthorn (Hippophae rhamnoides L.) is a small fruit tree belonging to the family Elaeagnaceae. Because seabuckthorn fruit is rich in unsaturated fatty acids and vitamins, this plant has potential as a food and medicinal crop. Here, we focused on symbiotic nitrogen fixation that could aid in the cultivation of this species. Microscopic observations showed that seabuckthorn root nodules have a standard morphology characteristic of Frankiaactinorhizal root nodules. Under nitrogen-free conditions, seabuckthorn seedlings inoculated with a homogenate of root nodules grew normally, and the fresh weight of root nodules was positively correlated with plant growth. In the field, nitrogenase activity in root nodules was high from May to September, when air temperatures were high and photosynthesis was active. Inhibition of nitrogen fixation by nitrate has been well documented in the root nodules of legumes. Therefore, we investigated the effect of nitrate on nitrogenase activity in seabuckthorn root nodules. Nitrogenase activity in seabuckthorn root nodules was not inhibited by the addition of high concentrations (up to 30 mM) of nitrate over a short term (5 days), but was apparently inhibited by long-term (20-30 days) treatments with 5 and 10 mM of nitrate.

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Suitability and use of the 15N-isotope dilution method to estimate nitrogen fixation by actinorhizal shrubs

Cited by 41 publications

References 32 publications

An analysis of soil respiration across northern hemisphere temperate ecosystems

An analysis of soil respiration across northern hemisphere temperate ecosystems

Symbiotic nitrogen fixation by legumes in two Chinese grasslands estimated with the 15N dilution technique

Nitrogen Fixation in Seabuckthorn (Hippophae rhamnoides L.) Root Nodules and Effect of Nitrate on Nitrogenase Activity

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