Contribution of winter processes to soil nitrogen flux in taiga forest ecosystems

Kielland, Knut; Olson, Karl; Ruess, Roger W.; Boone, Richard D.

doi:10.1007/s10533-006-9045-3

Cited by 75 publications

(66 citation statements)

References 36 publications

(35 reference statements)

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“…The higher temperatures may have stimulated mineralization, freed N from microbial cells lysed during freeze-thaw, released N trapped in the snow, or all of the above. In any case, this midwinter increase in N mineralization may be overlooked in studies that allow buried bags to incubate from late fall through April or May (e.g., Kielland et al 2006, Miller et al 2009, Turner and Henry 2010. Such a sampling scheme may provide an estimate of total winter N mineralization, but it may not capture the response of soils to fluctuating winter temperatures that are expected to be more common as climate changes.…”

Section: Discussionmentioning

confidence: 99%

“…Until recently, winter has been perceived as a ''dormant'' period based on the belief that biological activity declines when temperatures grow cold (Campbell et al 2005). However, research in areas with seasonal snowpack has demonstrated significant contributions of winter C and N fluxes to the total annual flux , Knoepp and Swank 2002, Mo et al 2005, Groffman et al 2006, Kielland et al 2006, Groffman et al 2009). As a result, changes in winter soil C and N cycling due to higher temperatures and/or N inputs may have negative ecosystem consequences.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal dynamics of soil respiration and N mineralization in chronically warmed and fertilized soils

Contosta¹,

Frey²,

Cooper³

2011

Ecosphere

149

133

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Abstract. Although numerous studies have examined the individual effects of increased temperatures and N deposition on soil biogeochemical cycling, few have considered how these disturbances interact to impact soil C and N dynamics. Likewise, many have not assessed season-specific responses to warming and N inputs despite seasonal variability in soil processes. We studied interactions among season, warming, and N additions on soil respiration and N mineralization at the Soil Warming 3 Nitrogen Addition Study at the Harvard Forest. Of particular interest were wintertime fluxes of C and N typically excluded from investigations of soils and global change. Soils were warmed to 58C above ambient, and N was applied at a rate of 5 g m À2 y À1 . Soil respiration and N mineralization were sampled over two years between 2007 and 2009 and showed strong seasonal patterns that mirrored changes in soil temperature.Winter fluxes of C and N contributed between 2 and 17% to the total annual flux. Net N mineralization increased in response to the experimental manipulations across all seasons, and was 8% higher in fertilized plots and 83% higher in warmed plots over the duration of the study. Soil respiration showed a more season-specific response. Nitrogen additions enhanced soil respiration by 14%, but this increase was significant only in summer and fall. Likewise, warming increased soil respiration by 44% over the whole study period, but the effect of warming was most pronounced in spring and fall. The only interaction between warming 3 N additions took place in autumn, when N availability likely diminished the positive effect of warming on soil respiration. Our results suggest that winter measurements of C and N are necessary to accurately describe winter biogeochemical processes. In addition, season-specific responses to the experimental treatments suggest that some components of the belowground community may be more susceptible to warming and N additions than others. Seasonal changes in the abiotic environment may have also interacted with the experimental manipulations to evoke biogeochemical responses at certain times of year.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Seasonal dynamics of soil respiration and N mineralization in chronically warmed and fertilized soils

Contosta¹,

Frey²,

Cooper³

2011

Ecosphere

149

133

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“…However, some researchers have suggested there is microbial activity in the winter. According to Kielland et al (2006) microbial processes continue in the soil even after the soil temperatures dip below zero degrees. At our site, some microorganisms were found in the beginning of the spring (Ivanova et al 2006).…”

Section: Seasonal Dynamics Of N In Soilmentioning

confidence: 99%

Nitrogen availability in the taiga forest ecosystem of northeastern Siberia

Popova

Tokuchi

Ohte

et al. 2013

Soil Science and Plant Nutrition

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The inorganic nitrogen (N) cycle and its dynamics in the soil were observed in the ecosystem at the Spasskaya Pad experimental forest near Yakutsk in northeastern Siberia in order to estimate the N availability for the larch (Larix cajanderi Mayr.) The soil pool of bulk N in the forest accounted for up to 866 g N m −2 (0-50 cm), whereas up to 1.7% (14.6 g N m −2 ) was potassium chloride (KCl)-extractable inorganic N. Ammonium was a dominant form of inorganic N. The size of the soil inorganic N pool fluctuated seasonally. It was small in the beginning of the summer and increased rapidly once the cumulative degree day of the soil temperature at 20 cm reached more than 300 (°C days), indicating that active N mineralization began at some point from the middle of July to the beginning of August. This soil pool of inorganic N that had accumulated at the end of the previous summer was consumed by the beginning of the next summer through microbial immobilization, which may have begun in September. Recycling of N in the soil was important because the input of inorganic N by deposition was very small (48 mg N m −2 year −1). A tracer 15 N experiment showed that larch did not uptake organic N in the form of amino acid (alanine); rather, it used ammonium and nitrate as N sources. The amount of available N for plants was assessed as water-extractable inorganic N in the soil solution that was transported to the rooting area by mass flow driven by plant transpiration, and it accounted for 1.9 × 10 3 (1.2 × 10 3 for trees) mg N m −2 during the growing season −1 (0-50 cm of the mineral soil layer in June, July, and August). Microorganisms in the soil are also expected to be competing for this available N. Our results show that despite a large amount of inorganic N production, N availability for plants is low as the soil pool of inorganic N is built up at the same rate as larch senescence.

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“…However, based on the investigation of more indirect parameters of N turnover such as soil mineral N concentrations, several studies showed that significant biogeochemical C and N turnover can occur in frozen soils and during freeze/thaw periods (Vogt et al 1986, Clein and Schimel 1995, Brooks et al 1999. Soil microbial N turnover may occur in winter under snowpack in the soil, as indicated e.g., by measurements of significant net N turnover rates in continental steppe of China (Zhou et al 2009, Zhao et al 2010, boreal forests (Kielland et al 2006), arctic tundra , and temperate hardwood forests (Groffman et al 2001b). Furthermore, microbial biomass and the activities of several soil enzymes were even found to peak in late winter in alpine soils (Lipson et al 1999(Lipson et al , 2002.…”

Section: Introductionmentioning

confidence: 99%

Seasonality of soil microbial nitrogen turnover in continental steppe soils of Inner Mongolia

Dannenmann

Wolf

et al. 2012

Ecosphere

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). Four different seasons with characteristic functional patterns of N turnover were identified: (1) Growing season dynamics as characterized by drying/rewetting cycles and negatively correlated temporal courses of net microbial growth and periods with intensive gross ammonification, contributing 40-52% and 29-32% to cumulative annual gross ammonification and nitrification, respectively. Net N mineralization was almost exclusively observed during the growing season. (2) Microbial N dynamics during the autumn freeze-thaw period was characterized by a sharp decline in microbial biomass in conjunction with a peak of gross nitrification contributing 19-36% to cumulative annual fluxes. (3) During winter at constantly frozen soil, a net build-up of microbial biomass was observed, whereas gross N turnover rates were low, contributing 7-10% and 6-11% to cumulative annual gross ammonification or gross nitrification, respectively. (4) The spring freeze-thaw period showed extremely dynamic changes in gross N turnover and soil nitrate concentrations. This period contributed 34-44% and 21-46% to cumulative annual gross ammonification and nitrification, respectively. This study highlights that freeze-thaw cycles are key periods for understanding patterns and magnitudes of gross N turnover in semi-arid continental steppe ecosystems. The results further imply that the observed patterns of microbial biomass and gross N turnover dynamics are likely the consequence of a seasonal succession of microbial communities and turnover of microbial biomass. Our findings emphasize the necessity for high resolution studies on gross N turnover as a prerequisite to infer functioning and annual budgets of ecosystem N cycling.

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Contribution of winter processes to soil nitrogen flux in taiga forest ecosystems

Cited by 75 publications

References 36 publications

Seasonal dynamics of soil respiration and N mineralization in chronically warmed and fertilized soils

Seasonal dynamics of soil respiration and N mineralization in chronically warmed and fertilized soils

Nitrogen availability in the taiga forest ecosystem of northeastern Siberia

Seasonality of soil microbial nitrogen turnover in continental steppe soils of Inner Mongolia

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