Shoot and root biomass production in semi-arid shrublands exposed to long-term experimental N input

Vourlitis, George L.; Jaureguy, Jeff; Marín, L. Natividad; Rodriguez, Charlton

doi:10.1016/j.scitotenv.2020.142204

Cited by 10 publications

(12 citation statements)

References 59 publications

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“…Fertilization had no effects on soil C fractions, except for at one site, where the MAOC fraction decreased likely because of changes in soil physicochemical properties induced by acidification. Contrary to previous studies, POC did not increase despite above‐ground biomass increasing in three of the four study systems (Parolari et al, 2012; Vourlitis, Jaureguy, et al, 2021) coupled to a likely decrease in biotic decomposition in soil–soil microbial biomass and extracellular enzyme activities decreased—in the two sites that experienced strong acidification. Furthermore, we found no evidence for a microbial C pump governing the persistence of soil C under N enrichment in these drylands; long‐term but not short‐term CUE and CSE increased in one of the non‐acidified sites but did not lead to changes in MAOC.…”

Section: Discussioncontrasting

confidence: 97%

“… Note : MAP is mean annual precipitation. Information presented in this table is derived from Fenn et al (2010), Khalili et al (2016), Potts et al (2012) and Vourlitis, Jaureguy, et al (2021). …”

Section: Methodsmentioning

confidence: 99%

“…CHAP and CSS1 are extensively described in Vourlitis, Jaureguy, et al (2021). Mean annual precipitation at CHAP is 382 mm.…”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, we assessed C stabilization efficiency (CSE) and CUE by measuring the efficiency by which microbes retained 13 C‐labelled glucose in soil, during both short‐ and long‐term incubations. We hypothesized that (a) the previously reported increase in plant growth in response to N addition at three of the sites (Parolari et al, 2012; Vourlitis, Jaureguy, et al, 2021) would increase POC, particularly in acidified plots where decomposition might be inhibited; (b) N enrichment would increase CSE and the transformation of POC into MAOC in non‐acidified plots; and (c) N enrichment would decrease exchangeable Ca and MAOC in acidified plots.…”

Section: Introductionmentioning

confidence: 99%

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Effects of experimental nitrogen deposition on soil organic carbon storage in Southern California drylands

Püspök

Zhao

Calma

et al. 2022

Global Change Biology

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Atmospheric nitrogen (N) deposition is enriching soils with N across biomes. Soil N enrichment can increase plant productivity and affect microbial activity, thereby increasing soil organic carbon (SOC), but such responses vary across biomes. Drylands cover ~45% of Earth's land area and store ~33% of global SOC contained in the top 1 m of soil. Nitrogen fertilization could, therefore, disproportionately impact carbon (C) cycling, yet whether dryland SOC storage increases with N remains unclear. To understand how N enrichment may change SOC storage, we separated SOC into plant-derived, particulate organic C (POC), and largely microbially derived, mineralassociated organic C (MAOC) at four N deposition experimental sites in Southern California. Theory suggests that N enrichment increases the efficiency by which microbes build MAOC (C stabilization efficiency) if soil pH stays constant. But if soils acidify, a common response to N enrichment, then microbial biomass and enzymatic organic matter decay may decrease, increasing POC but not MAOC. We found that N enrichment had no effect on C fractions except for a decrease in MAOC at one site.Specifically, despite reported increases in plant biomass in three sites and decreases in microbial biomass and extracellular enzyme activities in two sites that acidified, POC did not increase. Furthermore, microbial C use and stabilization efficiency increased in a non-acidified site, but without increasing MAOC. Instead, MAOC decreased by 16% at one of the sites that acidified, likely because it lost 47% of the exchangeable calcium (Ca) relative to controls. Indeed, MAOC was strongly and positively affected by Ca, which directly and, through its positive effect on microbial biomass, explained 58% of variation in MAOC. Long-term effects of N fertilization on dryland SOC storage appear abiotic in nature, such that drylands where Ca-stabilization of SOC is prevalent and soils acidify, are most at risk for significant C loss.

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Section: Discussioncontrasting

confidence: 97%

Section: Methodsmentioning

confidence: 99%

“…CHAP and CSS1 are extensively described in Vourlitis, Jaureguy, et al (2021). Mean annual precipitation at CHAP is 382 mm.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of experimental nitrogen deposition on soil organic carbon storage in Southern California drylands

Püspök

Zhao

Calma

et al. 2022

Global Change Biology

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“…The fire regime is characterized by large and high‐intensity crown fires that occur ~30–100 years apart and during the dry season (Parker et al, 2016). Chaparral occurs on a variety of soils that are generally nutrient poor, and productivity is limited by nitrogen (Vourlitis et al, 2021a). Several anthropogenic environmental changes affect chaparral, including warming and drying climates (Diffenbaugh et al, 2015), nitrogen deposition downwind from urban areas (Bytnerowicz et al, 2016), increased fire frequency (Syphard et al, 2007), and many types of disturbance that promote populations of exotic annual species.…”

Section: Factors Controlling Chaparral Ecosystemsmentioning

confidence: 99%

Vegetation‐type conversion of evergreen chaparral shrublands to savannahs dominated by exotic annual herbs: causes and consequences for ecosystem function

Pratt

2021

American J of Botany

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Woody, evergreen shrublands are the archetypal community in mediterranean‐type ecosystems, and these communities are profoundly changed when they undergo vegetation‐type conversion (VTC) to become annual, herb‐dominated communities. Recently, VTC has occurred throughout southern California chaparral shrublands, likely with changes in important ecosystem functions. The mechanisms that lead to VTC and subsequent changes to ecosystem processes are important to understand as they have regional and global implications for ecosystem services, climate change, land management, and policy. The main drivers of VTC are altered fire regimes, aridity, and anthropogenic disturbance. Some changes to ecosystem function are certain to occur with VTC, but their magnitudes are unclear, whereas other changes are unpredictable. I present two hypotheses: (1) VTC leads to warming that creates a positive feedback promoting additional VTC, and (2) altered nitrogen dynamics create negative feedbacks and promote an alternative stable state in which communities are dominated by herbs. The patterns described for California are mostly relevant to the other mediterranean‐type shrublands of the globe, which are biodiversity hotspots and threatened by VTC. This review examines the extent and causes of VTC, ecosystem effects, and future research priorities.

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Progressively decreased nitrogen-stimulation of soil phosphatase activity with long-term nitrogen addition

Chen

Moorhead

2022

Applied Soil Ecology

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Shoot and root biomass production in semi-arid shrublands exposed to long-term experimental N input

Cited by 10 publications

References 59 publications

Effects of experimental nitrogen deposition on soil organic carbon storage in Southern California drylands

Effects of experimental nitrogen deposition on soil organic carbon storage in Southern California drylands

Vegetation‐type conversion of evergreen chaparral shrublands to savannahs dominated by exotic annual herbs: causes and consequences for ecosystem function

Progressively decreased nitrogen-stimulation of soil phosphatase activity with long-term nitrogen addition

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