Nitrogen and carbon mineralization of semi-arid shrubland soil exposed to long-term atmospheric nitrogen deposition

Vourlitis, George L.; Zorba, Gypsi

doi:10.1007/s00374-006-0137-y

Cited by 37 publications

(21 citation statements)

References 21 publications

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“…Although low moisture limits microbial processes (Stark and Firestone 1995), soil microbes can be adapted to droughtinduced stress (Schimel and others 2007), so that NH 4 + accumulated during the dry season can diffuse to surviving nitrifiers once soil hydrologic connectivity is re-established (Parker and Schimel 2011). We hypothesize that atmospheric NH 4 + moved along shallow surface flowpaths (Swarowsky and others 2012) where rapid nitrification occurred (Vourlitis and Zorba 2007). It is also possible that atmospheric NH 4 + that escaped nitrification in soils was nitrified in the riparian stream-zone; instream nitrification has been shown to occur within short distances (10-100 m; Curtis and others 2011).…”

Section: Is the Hydrologic Flushing Of Biologically Unprocessed Dry Dmentioning

confidence: 91%

Assessing Nitrogen-Saturation in a Seasonally Dry Chaparral Watershed: Limitations of Traditional Indicators of N-Saturation

et al. 2014

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To evaluate nitrogen (N) saturation in xeric environments, we measured hydrologic N losses, soil N pools, and microbial processes, and developed an N-budget for a chaparral catchment (Sierra Nevada, California) exposed to atmospheric N inputs of approximately 8.5 kg N ha -1 y -1. Dual-isotopic techniques were used to trace the sources and processes controlling nitrate (NO 3 -) losses. The majority of N inputs occurred as ammonium. At the onset of the wet season (November to April), we observed elevated streamwater NO 3 -concentrations (up to 520 lmol l -1 ), concomitant with the period of highest gaseous N-loss (up to 500 ng N m -2 s -1 ) and suggesting N-saturation. Stream NO 3 -d 15N and d 18O and soil N measurements indicate that nitrification controlled NO 3 -losses and that less than 1% of the loss was of atmospheric origin. During the late wet season, stream NO 3 -concentrations decreased (to <2 lmol l -1 ) as did gaseous N emissions, together suggesting conditions no longer indicative of N-saturation. We propose that chaparral catchments are temporarily N-saturated at £ 8.5 kg N ha -1 y -1 , but that N-saturation may be difficult to reach in ecosystems that inherently leak N, thereby confounding the application of N-saturation indicators and annual N-budgets. We propose that activation of N sinks during the typically rainy winter growing season should be incorporated into the assessment of ecosystem response to N deposition. Specifically, the N-saturation status of chaparral may be better assessed by how rapidly catchments transition from N-loss to N-retention.

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Section: Is the Hydrologic Flushing Of Biologically Unprocessed Dry Dmentioning

confidence: 91%

Assessing Nitrogen-Saturation in a Seasonally Dry Chaparral Watershed: Limitations of Traditional Indicators of N-Saturation

et al. 2014

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“…Given the significant ecosystem N enrichment (Vourlitis and Zorba 2007, Vourlitis et al 2007a) and changes in plant species composition ) that were observed over the duration of this experiment, and the fact that chaparral shrub productivity is reportedly N limited (McMaster et al 1982, Gray and Schlesinger 1983, it was hypothesized that chronic dry-season N exposure would significantly increase the NPP of these semi-arid shrublands. This hypothesis was supported for the chaparral and CSS shrublands studied here; however, not without caveats.…”

Section: Discussionmentioning

confidence: 99%

“…Nitrogen inputs consistently increased soil N availability from direct fertilization and an increase in N mineralization , Sirulnik et al 2007, Vourlitis and Zorba 2007, Vourlitis et al 2007a). An increase in nitrification has led to higher rates of base-cation leaching Poth 1999, Meixner and and soil acidification (Wood et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Aboveground net primary production response of semi‐arid shrublands to chronic experimental dry‐season N input

Vourlitis

2012

Ecosphere

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Abstract. Urban chaparral and coastal sage scrub (CSS) shrublands of southern Californian have been exposed to high-levels of dry-atmospheric nitrogen (N) deposition for decades. The productivity of these semi-arid shrublands is reportedly N limited, thus N exposure is hypothesized to cause an increase in aboveground net primary production (NPP). To test this hypothesis the aboveground biomass and litter production of a post-fire chaparral and a mature CSS stand were measured over an 8 year period in plots exposed to either ambient or elevated N input (ambient þ 50 kg N ha À1 y À1). Results support this hypothesis; however, trends in NPP varied over time or were affected by rainfall. For post-fire chaparral, NPP was initially inhibited by N input, but over time NPP increased consistently in plots exposed to added N. For CSS, the effect of N exposure was positively correlated with annual rainfall and N exposure caused NPP to increase significantly when rainfall exceeded approximately 450 mm year À1 . Thus, while N enrichment may increase the NPP of these semi-arid shrublands, temporal patterns may take years to emerge or be dependent on water availability. These results highlight the importance of long-term experiments and the potential for interactions between water and nutrients in semi-arid ecosystems.

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“…The influence of N input on net N mineralization and N bioavailability in soils (Aerts et al 2006;Vourlitis et al 2007;Sirulnik et al 2007), microbial biomass (Jana et al 2005;John et al 2004;Allen et al 2004), soil enzyme activities (Hu et al 2013;Frey et al 2004), aboveground primary productivity, and plant community composition (Nkana et al 1999;Prieto 2009) have been investigated. N addition can alter the diversity and composition of soil microbial communities (Balser et al 2001;Allison et al 2008;Campbell et al 2010;Ramirez et al 2010;Bates et al 2011), decrease the bacterial/fungal biomass ratio and fungal-lignin degrading enzyme activity (Frey et al 2004), and suppress soil microbial activity by altering the metabolic capabilities of soil bacterial communities (Kelly et al 2012).…”

mentioning

confidence: 99%

Response of fungal composition and diversity to simulated nitrogen deposition and manipulation of precipitation in soils of an Inner Mongolia desert steppe of Northern China

Jia

Liu

et al. 2017

Can. J. Soil. Sci.

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Nitrogen and carbon mineralization of semi-arid shrubland soil exposed to long-term atmospheric nitrogen deposition

Cited by 37 publications

References 21 publications

Assessing Nitrogen-Saturation in a Seasonally Dry Chaparral Watershed: Limitations of Traditional Indicators of N-Saturation

Assessing Nitrogen-Saturation in a Seasonally Dry Chaparral Watershed: Limitations of Traditional Indicators of N-Saturation

Aboveground net primary production response of semi‐arid shrublands to chronic experimental dry‐season N input

Response of fungal composition and diversity to simulated nitrogen deposition and manipulation of precipitation in soils of an Inner Mongolia desert steppe of Northern China

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