Conservation of nitrogen increases with precipitation across a major grassland gradient in the Central Great Plains of North America

McCulley, Rebecca L.; Burke, Ingrid C.; Lauenroth, William K.

doi:10.1007/s00442-008-1229-1

Cited by 89 publications

(92 citation statements)

References 64 publications

(66 reference statements)

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“…First, highly pulsed rainfall events typically found in drylands 30,31 may decouple plant N uptake with soil microbial N transformation in areas with AIo0.32. When the threshold AI ¼ 0.32 was passed, these two processes are probably coupled, resulting in higher N retention efficiency (that is, higher f plant ) with increasing AI.…”

Section: Discussionmentioning

confidence: 99%

Aridity threshold in controlling ecosystem nitrogen cycling in arid and semi-arid grasslands

et al. 2014

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Higher aridity and more extreme rainfall events in drylands are predicted due to climate change. Yet, it is unclear how changing precipitation regimes may affect nitrogen (N) cycling, especially in areas with extremely high aridity. Here we investigate soil N isotopic values (d 15 N) along a 3,200 km aridity gradient and reveal a hump-shaped relationship between soil d 15 N and aridity index (AI) with a threshold at AI ¼ 0.32. Variations of foliar d 15 N, the abundance of nitrification and denitrification genes, and metabolic quotient along the gradient provide further evidence for the existence of this threshold. Data support the hypothesis that the increase of gaseous N loss is higher than the increase of net plant N accumulation with increasing AI below AI ¼ 0.32, while the opposite is favoured above this threshold. Our results highlight the importance of N-cycling microbes in extremely dry areas and suggest different controlling factors of N-cycling on either side of the threshold.

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Section: Discussionmentioning

confidence: 99%

Aridity threshold in controlling ecosystem nitrogen cycling in arid and semi-arid grasslands

et al. 2014

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“…At the local scale, some studies report that mineral N concentration decreases with increasing water availability (Fisher et al 1987) and some report the opposite pattern (Whitford et al 1995). Other studies show that net N mineralization does not differ between dry or wet soils (Schimel and Parton 1986, Reynolds et al 1999, Yahdjian et al 2006, or across precipitation gradients in the Great Plains (McCulley et al 2009). A metaanalysis of aboveground net primary production (ANPP) responses to N fertilization across arid to subhumid ecosystems showed that the importance of N limitation increases with annual precipitation from arid to subhumid regions (Yahdjian et al 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Drier sites along precipitation gradients have shown a more ''open'' N cycle than sites receiving higher precipitation (Handley et al 1999), which means that the loss relative to N cycled between plants and soil is larger than in wetter sites. Thus, the indirect effect of precipitation through changes in the openness of the N cycle has significant impacts on ecosystem functioning, and has been proposed to maintain water and N co-limitation in semi-arid ecosystems (McCulley et al 2009). Within this context, we were interested in looking at the degree of synchrony between N availability and demand and how this relationship changes in dry and wet years in a desert grassland.…”

Section: Introductionmentioning

confidence: 99%

Water controls on nitrogen transformations and stocks in an arid ecosystem

Reichmann¹,

Sala²,

Peters³

2013

Ecosphere

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Abstract. Following water, nitrogen (N) is the most frequent limiting factor to aboveground net primary production in arid ecosystems. Increased water availability can stimulate both plant nitrogen uptake and microbial nitrogen mineralization, but may also stimulate losses from the ecosystem. Here, we assess the effect of water availability on nitrogen stocks and transformations in an arid ecosystem. We conducted a field experiment with five levels of precipitation input (À80%, À50%, ambient, þ50%, þ80%) and two levels of N fertilization (ambient or 10 gÁm À2 Áyr À1 NH 4 NO 3 ) in a desert grassland of the Chihuahuan Desert. We measured in situ net N mineralization, plant N uptake, foliar N, N leaching under grass-rooting zone, and soil N availability during two years. Our results showed that increased water availability did not affect net N mineralization, but there was higher plant N uptake than with drought. Soil inorganic N pools were 2-4 times lower with increased water availability compared to drought conditions. N leaching below grass-rooting zone was higher in dry than wet conditions because of higher available N. Increased water availability differentially affected N species significantly reducing the NO 3 :NH 4 ratio. The accumulation of inorganic N during drought was the result of a decoupling between microbial and plant activity, and suggests that the cycling of N is more open in dry years than in wet years.

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“…Vegetation drives maximum C input to the soil and varies across ecosystem biomes, primarily with moisture gradients (Del Grosso et al 2008;Jobbagy and Jackson 2000). Consequently, SOC and SON stocks are also highly related to temperature and precipitation gradients (Jenny 1941;Burke et al 1989;McCulley et al 2009). Temperature and moisture serve as controls to soil organic matter (SOM) decomposition and CO 2 respiration (Jobbagy and Jackson 2000;Conant et al 2004), driving both global and regional patterns of SOC.…”

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confidence: 99%

Effects of climate change on soil carbon and nitrogen storage in the US Great Plains

Follett¹,

Stewart²,

Pruessner³

et al. 2012

Journal of Soil and Water Conservation

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Soils of the US Great Plains contain enormous stocks of soil organic carbon (SOC) and soil organic nitrogen (SON) that are vulnerable to predicted climate and land use change. Climate change scenarios predict a 2.2°C to 3.6°C (4°F to 6.5°F) increase and more variability in precipitation across most of the United States. This study quantifies management effects (native grassland, Conservation Reserve Program [CRP], and cropped) on SOC and SON stocks across the region and assessed soil variables (soil texture, cation exchange capacity, and others) and climatic drivers (precipitation and temperature) to predict future changes in carbon (C) and nitrogen (N) stocks. Across all sites, cropped land had significantly lower C and N stocks in the 0 to 5 cm (0 to 2 in) and 0 to 10 cm (0 to 3.9 in) depths than native sites, while CRP sites were intermediate. Mean annual temperature (MAT), the ratio of mean annual precipitation to potential evapotranspiration (MAP:PET), soil bulk density (BD), and clay content were important covariates for SOC and SON stocks within land use. Soil C and N stocks under all three land uses were strongly negatively related to MAT and positively related to MAP:PET, suggesting that they are equally vulnerable to increased temperature and decreasing water availability. Based on these empirical relationships, a 1ºC (1.8ºF) increase in MAT could cause a loss of 486 Tg SOC (536 million tn) and a loss of 180 kg SON ha ) from the top 10 cm (3.9 in) of soil over 30 years, but the decrease will be mediated by water availability (MAP:PET). Combined, increased temperature and conversion from CRP to cropland could decrease the existing SOC sink, but improved soil management and increased water availability may help offset these losses in the US Great Plains.

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Conservation of nitrogen increases with precipitation across a major grassland gradient in the Central Great Plains of North America

Cited by 89 publications

References 64 publications

Aridity threshold in controlling ecosystem nitrogen cycling in arid and semi-arid grasslands

Aridity threshold in controlling ecosystem nitrogen cycling in arid and semi-arid grasslands

Water controls on nitrogen transformations and stocks in an arid ecosystem

Effects of climate change on soil carbon and nitrogen storage in the US Great Plains

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