Topographical Differences in Soil N Transformation Using<sup>15</sup>N Dilution Method along a Slope in a Conifer Plantation Forest in Japan

Tokuchi, Naoko; Hirobe, Muneto; Koba, Keisuke

doi:10.1007/bf02762758

Cited by 21 publications

(28 citation statements)

References 19 publications

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“…A lack of net nitrification is not always indicative of a lack of gross nitrification (Davidson et al 1992;Hart et al 1994). Even though most NO 3 − was readily immobilized by soil microbes, gross nitrification still occurred in Cryptomeria japonica plantations with soils without NO 3 − pools or net nitrification (Tokuchi et al 2000;Hirobe et al 2003). Inorganic N flux measurements, based on ion exchange resin bags buried at 50-cm depths in mineral soil, revealed that NO 3 − flux occurred, even in upper slopes (Tokuchi et al, unpublished data), suggesting the occurrence of gross nitrification.…”

Section: Resultsmentioning

confidence: 98%

“…Two soil habitat types with differences based on N transformation patterns were identified along a slope; the lower part of the slope had large nitrate pools and high net nitrification rates, while the upper part of the slope had no to small nitrate pools and low net nitrification rates (Garten et al 1994;Hirobe et al 1998;Tokuchi et al 2000;Tateno and Takeda 2003). The former condition is thought to indicate higher N availability than the latter, because plants can more readily take up nitrate than ammonium (e.g., Binkley and Vitousek 1989).…”

Section: Introductionmentioning

confidence: 99%

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Inorganic nitrogen source utilization byFagus crenata on different soil types

Tateno

Terai

Tokuchi

et al. 2005

Trees

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The nitrogen source utilization by Fagus crenata distributed on soils with different forms of inorganic nitrogen in a cool-temperate deciduous forest in central Japan was determined by measuring foliar δ 15 N. Two soil habitat types along a slope were delineated based on nitrogen transformation patterns, i.e., soils with high net nitrification rates and with no or low net nitrification, respectively. Despite differences in soil types, the study species, F. crenata, was distributed along the entire slope. The foliar δ 15 N value of F. crenata from the lower slope area was significantly lower than that from the upper slope. Given the finding of a previous study that the δ 15 N of NO 3 − was lower than that of NH 4 + , our results indicate that reliance on NO 3 − as a nitrogen source was greater in the lower slope area than in the upper slope area. Differences in the values of foliar δ 15 N were about 1‰, which is far less than the 10‰ δ 15 N value of soil inorganic N reported in the previous study. This discrepancy might suggest that the study species utilized NO 3 − even in the upper site where net nitrification had not been detected. Measurements of nitrate reductase activity, an index of NO 3 − uptake, also supported this interpretation. Nitrate reduction occurred in leaves and roots at R. Tateno ( ) · N. Osada · M. Terai · H. Takeda

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Inorganic nitrogen source utilization byFagus crenata on different soil types

Tateno

Terai

Tokuchi

et al. 2005

Trees

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“…This limits discussion of how stand development affects soil N dynamics. However, Japanese cedar plantation forests under the same climatic and geologic conditions have a relatively homogeneous soil environment, despite the effect of topography-mediated conditions (Hirobe et al 1998;Tokuchi et al 2000;Ichikawa et al 2003). Thus, to compare soil N dynamics among forest watersheds of different ages, we established soil pits in each watershed at a similar position on a lower slope (i.e., a similar distance from a stream; Fig.…”

Section: Discussionmentioning

confidence: 99%

Soil nitrogen dynamics during stand development after clear-cutting of Japanese cedar (Cryptomeria japonica) plantations

Fukushima

Tateno

Tokuchi

2011

Journal of Forest Research

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We examined soil N dynamics, including inorganic N concentration, net N transformation rates, and estimated plant N uptake (EPNU) from soil N budgets, and litterfall inputs, in five Japanese cedar plantation stands of different ages (5, 16, 31, 42, and 89 years) in the Mt Gomadan Experimental Forest (GEF). Net soil N mineralization and nitrification rates did not differ significantly between the youngest and oldest stands; soil moisture and inorganic N concentration were higher in the youngest stand. The EPNU was highest in the 16-year-old stand and lowest in the 31-year-old stand, and had a significant negative correlation with litter C:N ratio. The oldest (89-year-old) stand had a higher soil C:N ratio, lower proportion of nitrification rate to mineralization rate (%NIT), and higher estimated plant NH 4? uptake than did the other stands, indicating that changes of soil organic matter quality can alter soil N dynamics. These results suggest that as a Japanese cedar plantation develops, soil N dynamics can be altered by the quantity and quality of input litter and soil organic matter, and can generate the imbalance between N supply from soil and N demand by plant.

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“…Davidson et al (1992) pointed out, however, that neither the relative size of the NO 3 -pool nor net changes in NO 3 -pool sizes over time is a good index of the importance of NO 3 -in the internal N cycle of an ecosystem. Actually, some studies describe rapid turnover of NO 3 -and high significant gross nitrification rate despite small NO 3 -pool and low net nitrification in forest soils (Davidson et al 1992;Tokuchi et al 2000). Hart et al (1994) reported that the best measure of the relative dynamics of NH 4 ?…”

Section: Site Characteristics Of N Transformation Ratesmentioning

confidence: 99%

Gross nitrification rates in four Japanese forest soils: heterotrophic versus autotrophic and the regulation factors for the nitrification

Kuroiwa

Koba

Isobe

et al. 2011

Journal of Forest Research

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Measurements of gross NH 4 ? and NO 3-production in forest soils were conducted using the 15 N pool dilution method. Mineral topsoils (0-10 cm depth) were collected from four forests from northern to southern Japan with a natural climate gradient to elucidate the mechanisms regulating gross nitrification rates in forest soils. Additionally, we attempted to evaluate the relative importance of heterotrophic nitrification in gross total nitrification using acetylene as a specific inhibitor of autotrophic nitrification. Distinct differences were found among sites in the gross rates of NH 4 ? production (3.1-11.4 mg N kg -1 day -1 ) and gross total nitrification (0.0-6.1 mg N kg -1 day -1 ). The rates of gross heterotrophic nitrification were low in this study, indicating that heterotrophic nitrification is of minor importance in most forest mineral topsoils in Japan. Significant relations were found between gross autotrophic nitrification and gross NH 4 ? production, soil N, and soil C concentrations, but none was found between gross autotrophic nitrification and soil pH. We determined the critical value of the gross NH 4? production rates for gross autotrophic nitrification under which no gross autotrophic nitrification occurred, as well as the critical soil C/N ratio above which gross autotrophic nitrification ceased. Results show that tight coupling of production and consumption of NH 4 ? prevents autotrophic nitrifiers from utilizing NH 4 ? as long as NH 4 ? availability is low.

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Topographical Differences in Soil N Transformation Using¹⁵N Dilution Method along a Slope in a Conifer Plantation Forest in Japan

Cited by 21 publications

References 19 publications

Inorganic nitrogen source utilization byFagus crenata on different soil types

Inorganic nitrogen source utilization byFagus crenata on different soil types

Soil nitrogen dynamics during stand development after clear-cutting of Japanese cedar (Cryptomeria japonica) plantations

Gross nitrification rates in four Japanese forest soils: heterotrophic versus autotrophic and the regulation factors for the nitrification

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Topographical Differences in Soil N Transformation Using15N Dilution Method along a Slope in a Conifer Plantation Forest in Japan

Cited by 21 publications

References 19 publications

Inorganic nitrogen source utilization byFagus crenata on different soil types

Inorganic nitrogen source utilization byFagus crenata on different soil types

Soil nitrogen dynamics during stand development after clear-cutting of Japanese cedar (Cryptomeria japonica) plantations

Gross nitrification rates in four Japanese forest soils: heterotrophic versus autotrophic and the regulation factors for the nitrification

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Topographical Differences in Soil N Transformation Using¹⁵N Dilution Method along a Slope in a Conifer Plantation Forest in Japan