Cross-biome assessment of gross soil nitrogen cycling in California ecosystems

Yang, Wendy H.; Ryals, Rebecca; Cusack, Daniela; Silver, Whendee L.

doi:10.1016/j.soilbio.2017.01.004

Cited by 57 publications

(49 citation statements)

References 94 publications

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“…Still, a few pieces of nitrogen pool and process data are available and can be used for spot comparisons. Yang, Ryals, Cusack, and Silver () quantified nitrate pools in 0–10 cm soil cores at five California forested sites, one site being the James Reserve where US‐SCf is located. They found average soil nitrate pools of approximately 0.2 mg/kg soil .…”

Section: Discussionmentioning

confidence: 99%

Hydraulic redistribution affects modeled carbon cycling via soil microbial activity and suppressed fire

Wang

Bible

et al. 2018

Global Change Biology

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Hydraulic redistribution (HR) of water from moist to drier soils, through plant roots, occurs world-wide in seasonally dry ecosystems. Although the influence of HR on landscape hydrology and plant water use has been amply demonstrated, HR's effects on microbe-controlled processes sensitive to soil moisture, including carbon and nutrient cycling at ecosystem scales, remain difficult to observe in the field and have not been integrated into a predictive framework. We incorporated a representation of HR into the Community Land Model (CLM4.5) and found the new model improved predictions of water, energy, and system-scale carbon fluxes observed by eddy covariance at four seasonally dry yet ecologically diverse temperate and tropical AmeriFlux sites. Modeled plant productivity and microbial activities were differentially stimulated by upward HR, resulting at times in increased plant demand outstripping increased nutrient supply. Modeled plant productivity and microbial activities were diminished by downward HR. Overall, inclusion of HR tended to increase modeled annual ecosystem uptake of CO (or reduce annual CO release to the atmosphere). Moreover, engagement of CLM4.5's ground-truthed fire module indicated that though HR increased modeled fuel load at all four sites, upward HR also moistened surface soil and hydrated vegetation sufficiently to limit the modeled spread of dry season fire and concomitant very large CO emissions to the atmosphere. Historically, fire has been a dominant ecological force in many seasonally dry ecosystems, and intensification of soil drought and altered precipitation regimes are expected for seasonally dry ecosystems in the future. HR may play an increasingly important role mitigating development of extreme soil water potential gradients and associated limitations on plant and soil microbial activities, and may inhibit the spread of fire in seasonally dry ecosystems.

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Section: Discussionmentioning

confidence: 99%

Hydraulic redistribution affects modeled carbon cycling via soil microbial activity and suppressed fire

Wang

Bible

et al. 2018

Global Change Biology

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“…However, DNRA is not the dominant process based on declining vertical distributions of NH4 + -N, although it has been documented as an important fate of NO3 − in anoxic sediments [43,[45][46][47]. The prevailing conceptual model of DNRA also suggests that it is restricted to highly reducing conditions [44,45,48]. At the north sites, NO3 − -N significantly increased from deep areas to a depth of 20-40 cm, and then decreased to surface sediments, but the NO2 − -N decreased continuously ( Figure 5).…”

Section: Effect Of Potential Biogeochemical Processes In the Hyporheimentioning

confidence: 99%

Potential Drivers of the Level and Distribution of Nitrogen in the Hyporheic Zone of Lake Taihu, China

Wang

Zhang

et al. 2017

Water

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Abstract:The hyporheic zone is the connection between surface water and groundwater that often plays an important function in nutrient transport and transformation, and acts as an active source of or sink for nutrients to the surface water, depending on its potential water flow patterns. Bottom surface water and sediments in the shallow hyporheic zone (approximately 100 cm depth) were sampled at 12 sites near the shoreline and two sites at the center of Lake Taihu (China) during spring and winter of 2016. Concentrations of total nitrogen, ammonium, nitrate, and nitrite in the bottom surface water and porewater (obtained from sediments using a frozen centrifugation method) were analyzed in a laboratory to establish the nitrogen distribution and potential drivers. The results show that, in general, the quality of bottom water and porewater near the shoreline was poor compared to that at the center, and it gradually improved from the northwestern to the southeastern zones of Lake Taihu. No significant relationship in nitrogen concentration was found between the bottom water and porewater in surface sediments. Nitrogen concentrations in porewater differed between sampling sites and sediment depths in Lake Taihu. Vertical profiles of nitrogen in porewater and differences in nitrogen between the winter and spring seasons indicated that potential upwelling water flow occurred in the hyporheic zone in the south, west, north, and center zones of Lake Taihu, but potentially weak water flow in variable directions likely occurred in the east zone. A strong reducing environment dominated the deep parts of the hyporheic zone (i.e., below 40 cm depth), while a weak oxidizing environment dominated the shallow parts. Furthermore, the decreasing total nitrogen and ammonium nitrogen from the deep to shallow depths in the hyporheic zones in the south, west, north, and center zones indicated that potential anammox and/or denitrification processes occurred. In the east zone, potential weak nitrification processes occurred in the hyporheic zone, and plant fixation and sedimentation of nitrogen also contributed to the surface sediments. In conclusion, the hyporheic zone near the shoreline in the south, west, and north sites of Lake Taihu acts as an active source of nitrogen for the lake water due to potential upwelling water flows, whereas the east site acts as an active source or sink due to seasonally variable directions in water flow. Water flow and biogeochemistry in the hyporheic zone jointly influence nutrient distribution in the hyporheic zone and even switch or alternate the source/sink function of sediment in surface water.

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“…A) to a less mobile form of ammonium (Yang et al. ), the lower abundance of assimilatory nitrate reduction to ammonium and dissimilatory nitrate reduction to ammonium genes might lead to lower nitrate and ammonium N contents in ARSP and ARMP than in NRSF soils (Fig. , Table ).…”

Section: Discussionmentioning

confidence: 99%

“…) indicated that the potential for ammonification, which is often regarded as a regulator of N availability in plants (Yang et al. ), was the least robust in the ARSP. Consistently, with the conversion of natural systems to artificial systems, both the abundances of ammonification genes (Berthrong et al.…”

Section: Discussionmentioning

confidence: 99%

Artificial reforestation produces less diverse soil nitrogen‐cycling genes than natural restoration

et al. 2019

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Reforestation is effective in restoring ecosystem functions and enhancing ecosystem services of degraded land. The three most commonly employed reforestation methods of natural reforestation, artificial reforestation with native Masson pine, and introduced slash pine plantations were equally successful in biomass yield in southern China. However, it is not known whether soil ecosystem functions, such as nitrogen (N) cycling, are also successfully restored. Here, we employed a functional microarray to illustrate soil N-cycling. The composition of N-cycling genes in soils varied significantly with reforestation method and varied with constructive species identity and plant diversity. Artificial reforestation had less superior organization of N-cycling genes than natural reforestation, as indicated by the less diverse and less stable pathways to perform the biogeochemical N-cycling processes. Besides, artificial reforestation had lower functional potential (abundance of ammonification, denitrification, assimilatory, and dissimilatory nitrate reduction to ammonium genes) in soils than natural method. Evaluations of the abundance and interactions of N-cycling genes in soils showed that plantations, especially artificial reforestation with slash pine plantations, possessed a smaller range of ecosystem functions that provide a less diverse array of N-related substrates and nutrients to microbial communities compared with natural restoration. This might lead to a lower independence of N-cycling, which indicated a higher risk of N release in plantations. The unfavorable N-cycling conditions in plantations were corroborated by the lower contents of available N, ammonium N, and nitrate N. These findings demonstrate that reforestation methods could have broad regional and possibly global implications for N-cycling.

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Cross-biome assessment of gross soil nitrogen cycling in California ecosystems

Cited by 57 publications

References 94 publications

Hydraulic redistribution affects modeled carbon cycling via soil microbial activity and suppressed fire

Hydraulic redistribution affects modeled carbon cycling via soil microbial activity and suppressed fire

Potential Drivers of the Level and Distribution of Nitrogen in the Hyporheic Zone of Lake Taihu, China

Artificial reforestation produces less diverse soil nitrogen‐cycling genes than natural restoration

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