Priming depletes soil carbon and releases nitrogen in a scrub-oak ecosystem exposed to elevated CO2

Langley, J. Adam; McKinley, Duncan C.; Wolf, Amelia A.; Hungate, Bruce A.; Drake, Bert G.; Megonigal, J. Patrick

doi:10.1016/j.soilbio.2008.09.016

Cited by 118 publications

(104 citation statements)

References 50 publications

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“…Several studies have reported that increasing C flux belowground in response to elevated atmospheric CO 2 results in increased microbial activity, faster decomposition of fresh organic matter, and increased breakdown of more recalcitrant pools of soil organic C (Langley et al, 2009;Drake et al, 2011). These results are consistent with more basic expectations that increasing simple carbohydrates to microbial communities increases, or primes the degradation of soil C and increases mineralization of nutrients previously immobilized in recalcitrant soil organic C (Kuzyakov et al, 2000).…”

Section: Impacts On Microbial Communities Soil Organic Matter and Ssupporting

confidence: 70%

Sensitivity of four ecological models to adjustments in fine root turnover rate

McCormack

Crisfield

Raczka

et al. 2015

Ecological Modelling

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A B S T R A C TLarge uncertainties surrounding root-specific parameters limit model descriptions of belowground processes and ultimately hinder understanding of belowground carbon (C) dynamics and terrestrial biogeochemistry. Despite this recognized shortcoming, it is unclear which processes warrant attention in model development, given the computational cost of additional model complexity. Here, we tested the sensitivity of four models to adjustments in fine root turnover in forested systems: CENTURY, ED2, MC1, and LANDCARB. In general, faster root turnover rates resulted in lower total system carbon (C) and within model changes ranged from 1% to 38% following 100-year simulations. However, the underlying mechanisms driving these changes differed among models as some expressed lower net primary productivity (NPP) with faster turnover rates and others had similar NPP but large shifts in C allocation away from wood to fine roots. Based on these findings we expect that different model responses to changes in fine root turnover will be determined by (1) whether C is allocated to fine roots as fixed portion of NPP or to maintain a fixed biomass ratio between fine roots and leaves or stems and (2) whether soil nutrient and water uptake is a function of both resource availability and fine root biomass or based on resource availability alone. These results suggest that better constrained estimates of fine root turnover will represent a valuable improvement in many terrestrial biosphere models.

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Section: Impacts On Microbial Communities Soil Organic Matter and Ssupporting

confidence: 70%

Sensitivity of four ecological models to adjustments in fine root turnover rate

McCormack

Crisfield

Raczka

et al. 2015

Ecological Modelling

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“…The parallel loss of soil C and increase in N mineralization in the study by Langley et al (2009) suggests that priming occurred due to microbial 'co-metabolism' of organic matter to acquire N (Kuzyakov et al 2000), which is often considered the limiting nutrient in temperate forests. In contrast, studies performed in tropical forests suggest that decomposition is limited by the availability of P (Hobbie and Vitousek 2000;Kaspari et al 2008).…”

Section: Introductionmentioning

confidence: 94%

“…Priming has been suggested as the cause of reductions in soil C in temperate forest grown under experimentally elevated CO 2 , despite increased inputs of plant-C to soils (Carney et al 2007;Langley et al 2009). The parallel loss of soil C and increase in N mineralization in the study by Langley et al (2009) suggests that priming occurred due to microbial 'co-metabolism' of organic matter to acquire N (Kuzyakov et al 2000), which is often considered the limiting nutrient in temperate forests.…”

Section: Introductionmentioning

confidence: 99%

Priming and microbial nutrient limitation in lowland tropical forest soils of contrasting fertility

et al. 2011

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“…The higher N mineralization rate may eventually lead to higher soil N availability for root uptake due to faster turnover of microbes compared to roots (Frank and Groffman, 2009;Kuzyakov and Xu, 2013). This microbial N mining hypothesis has been invoked as a mechanism to explain increased plant N uptake in elevated CO 2 studies (Zak et al, 1993;Cheng, 1999;Langley et al, 2009;Billings et al, 2010;Phillips et al, 2011), but only few studies (e.g. Herman et al, 2006;Dijkstra et al, 2009) have directly tested this hypothesis.…”

Section: Introductionmentioning

confidence: 99%

Rhizosphere priming effects on soil carbon and nitrogen mineralization

Zhu

Gutknecht

Herman

et al. 2014

Soil Biology and Biochemistry

339

153

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a b s t r a c tLiving roots and their rhizodeposits affect microbial activity and soil carbon (C) and nitrogen (N) mineralization. This so-called rhizosphere priming effect (RPE) has been increasingly recognized recently. However, the magnitude of the RPE and its driving mechanisms remain elusive. Here we investigated the RPE of two plant species (soybean and sunflower) grown in two soil types (a farm or a prairie soil) and sampled at two phenological stages (vegetative and mature stages) over an 88-day period in a greenhouse experiment. We measured soil C mineralization using a continuous 13 C-labeling method, and quantified gross N mineralization with a 15 N-pool dilution technique. We found that living roots significantly enhanced soil C mineralization, by 27e245%. This positive RPE on soil C mineralization did not vary between the two soils or the two phenological stages, but was significantly greater in sunflower compared to soybean. The magnitude of the RPE was positively correlated with rhizosphere respiration rate across all treatments, suggesting the variation of RPE among treatments was likely caused by variations in root activity and rhizodeposit quantity. Moreover, living roots stimulated gross N mineralization rate by 36e62% in five treatments, while they had no significant impact in the other three treatments. We also quantified soil microbial biomass and extracellular enzyme activity when plants were at the vegetative stage. Generally, living roots increased microbial biomass carbon by 0 e28%, b-glucosidase activity by 19e56%, and oxidative enzyme activity by 0e46%. These results are consistent with the positive rhizosphere effect on soil C (45e79%) and N (10e52%) mineralization measured at the same period. We also found significant positive relationships between b-glucosidase activity and soil C mineralization rates and between oxidative enzyme activity and gross N mineralization rates across treatments. These relationships provide clear evidence for the microbial activation hypothesis of RPE. Our results demonstrate that rootesoilemicrobial interactions can stimulate soil C and N mineralization through rhizosphere effects. The relationships between the RPE and rhizosphere respiration rate and soil enzyme activity can be used for explicit representations of RPE in soil organic matter models.Published by Elsevier Ltd.

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Priming depletes soil carbon and releases nitrogen in a scrub-oak ecosystem exposed to elevated CO2

Cited by 118 publications

References 50 publications

Sensitivity of four ecological models to adjustments in fine root turnover rate

Sensitivity of four ecological models to adjustments in fine root turnover rate

Priming and microbial nutrient limitation in lowland tropical forest soils of contrasting fertility

Rhizosphere priming effects on soil carbon and nitrogen mineralization

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