Spatial variability of soil nitrogen transformation patterns along a forest slope in a Cryptomeria japonica D. Don plantation

Hirobe, Muneto; Tokuchi, Naoko; Iwatsubo, Goro

doi:10.1016/s1164-5563(00)88649-5

Cited by 73 publications

(74 citation statements)

References 24 publications

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“…Likewise, total soil N concentrations were elevated in shoulder positions of cantenae underlain by N-rich shale substrates in the Shinga Prefecture, Japan (Hirobe et al, 1998). More directly, Morford et al (2011) demonstrated that the N content of soils and forest foliage collected from erosional slopes of N-rich metasedimentary rocks (350-950 ppm) was elevated by more than 50 % compared to similar temperate forest sites underlain by N-poor igneous parent material (30-70 ppm).…”

Section: Topographymentioning

confidence: 94%

A new synthesis for terrestrial nitrogen inputs

Houlton

Morford

2015

SOIL

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Abstract. Nitrogen (N) inputs sustain many different aspects of local soil processes, their services, and their interactions with the broader Earth system. We present a new synthesis for terrestrial N inputs that explicitly considers both rock and atmospheric sources of N. We review evidence for state-factor regulation over biological fixation, deposition, and rock-weathering inputs from local to global scales and in transient vs. steady-state landscapes. Our investigation highlights strong organism and topographic (relief) controls over all three N input pathways, with the anthropogenic factor clearly important in rising N deposition rates. In addition, the climate, parent material, and time factors are shown to influence patterns of fixation and rock-weathering inputs of N in diverse soil systems. Data reanalysis suggests that weathering of N-rich parent material could resolve several known cases of "missing N inputs" in ecosystems, and demonstrates how the inclusion of rock N sources into modern concepts can lead to a richer understanding of spatial and temporal patterns of ecosystem N availability. For example, explicit consideration of rock N inputs into classic pedogenic models (e.g., the Walker and Syers model) yields a fundamentally different expectation from the standard case: weathering of N-rich parent material could enhance N availability and facilitate terrestrial succession in developmentally young sites even in the absence of N-fixing organisms. We conclude that a state-factor framework for N complements our growing understanding multiple-source controls on phosphorus and cation availability in Earth's soil, but with significant exceptions given the lack of an N fixation analogue in all other biogeochemical cycles. Rather, non-symmetrical feedbacks among input pathways in which high N inputs via deposition or rock-weathering sources have the potential to reduce biological fixation rates mark N as fundamentally different from other nutrients. The new synthesis for terrestrial N inputs provides a novel set of research issues and opportunities in the multidisciplinary Earth system sciences, with implications for patterns of N limitation, tectonic controls over biogeochemical cycling, and carbon-nutrient-climate interactions.

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Section: Topographymentioning

confidence: 94%

A new synthesis for terrestrial nitrogen inputs

Houlton

Morford

2015

SOIL

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“…The N availability for plants can be strongly affected by the hydrological factors on a slope (Hill and Kemp, 1999;Band et al, 2001). Therefore, many studies have focused on the patterns of soil N dynamics and NO − 3 production as well as their controlling factors in forest slopes (Hirobe et al, 1998(Hirobe et al, , 2003Tokuchi et al, 2000;Nishina et al, 2009a,b;Koyama et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Microbial regulation of nitrogen dynamics along the hillslope of a natural forest

Isobe

Ohte

Oda

et al. 2015

Front. Environ. Sci.

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Topography affects the soil physicochemistry, soil N dynamics, and plant distribution and growth in forests. In Japan, many forests are found in mountainous areas and these traits are often highly variable along steep slopes. In this study, we investigated how the microbial population dynamics reflected the bioavailable N dynamics with the physicochemical gradient along the slope in soils of a natural forest in Japan. We measured the gross rates of NH + 4 production, nitrification, and NH + 4 / NO − 3 immobilization using the N isotope dilution method to analyze the N dynamics in the soils. We also determined the abundance of the bacterial 16S rRNA gene and bacterial and archaeal ammonia monooxygenase gene (amoA) using qPCR to assess the populations of total bacteria and nitrifiers. We found that gross rates of NH + 4 production and nitrification were higher in the lower part of the slope, they were positively correlated with the abundance of the bacterial 16S rRNA gene and archaeal amoA, respectively; and the availability of N, particularly NO − 3 , for plants was higher in the lower part of the slope because of the higher microbial nitrification activity and low microbial NO − 3 immobilization activity. In addition, path analysis indicated that gross rates of NH + 4 production and nitrification were regulated mainly by the substrate (dissolved organic N and NH + 4 ) concentrations and population sizes of total bacteria and nitrifiers, respectively, and their population sizes were strongly affected by the soil physicochemistry such as pH and water content. Our results suggested that the soil physicochemical gradient along the slope caused the spatial gradient of gross rates of NH + 4 production and nitrification by altering the communities of ammonifiers and nitrifiers in the forest slope, which also affected plant distribution and growth via the supply of bioavailable N to plants.

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“…Because topography regulates soil water movement and drainage, lower slopes tended to be moist and upper slopes drier, which created a biogeochemical gradient on the slope (Swanson et al 1988;Hirobe et al 1999;Tsui et al 2004). Likewise, soil respiration varies according to the topographical position on the hill slope.…”

Section: Introductionmentioning

confidence: 99%

Topographic variation in heterotrophic and autotrophic soil respiration in a tropical seasonal forest in Thailand

Takahashi

Hirai

Limtong³

et al. 2011

Soil Science and Plant Nutrition

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Soil respiration is a carbon flux that is indispensable for determining carbon balance despite variations over time and space in forest ecosystems. In Kanchanaburi, western Thailand, we measured the soil respiration rates at different slope positions-ridge (plot R), upper slope (plot U), and lower slope (plot L)-on a hill in a seasonal tropical forest [mixed deciduous forest (MDF)] to determine the seasonal and spatial variations in soil respiration on the slope. The heterotrophic (organic layer and soil) and autotrophic (root) respiration was differentiated by trenching. Soil respiration rates showed clear seasonal patterns: high and low rates in rainy and dry seasons respectively, at all plots, and tended to decrease up the slope. Soil respiration rates responded significantly to soil water content in the 0-30 cm layer, but the response patterns differed between the lower slope (plot L) and the upper slope (plots R and U): a linear model could be applied to the lower slope but exponential quadratic models to the upper slope. The annual carbon dioxide (CO 2 ) efflux from the forest floor was also associated with the slope position and ranged from 1908 gC m À2 year À1 in plot L to 1199 gC m À2 year À1 in plot R. With ascending position from plot L to R, the contribution of autotrophic respiration increased from 19.4 to 36.6% of total soil respiration, while that of the organic layer decreased from 26.2 to 9.4%. Mineral soil contributed to 46.3 to 54.4% of the total soil respiration. Soil water content was the key factor in controlling the soil respiration rate and the contribution of the respiration sources. However, the variable responses of soil respiration to soil water content create a complex distribution of soil respiration at the watershed scale.

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Spatial variability of soil nitrogen transformation patterns along a forest slope in a Cryptomeria japonica D. Don plantation

Cited by 73 publications

References 24 publications

A new synthesis for terrestrial nitrogen inputs

A new synthesis for terrestrial nitrogen inputs

Microbial regulation of nitrogen dynamics along the hillslope of a natural forest

Topographic variation in heterotrophic and autotrophic soil respiration in a tropical seasonal forest in Thailand

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