Effects of climatic change on the edaphic features of arid and semiarid lands of western North America

West, Neil E.; Stark, John; Johnson, Dale W.; Abrams, M. M.; Wight, J.R.; Heggem, Daniel T.; Peck, Susan

doi:10.1080/15324989409381408

Cited by 51 publications

(21 citation statements)

References 72 publications

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“…Of course, the magnitude and spatial location of material transport and retention will depend on the extent of the accumulation (duration of dry period) and the frequency and sequence of storms, while the mechanism of retention may vary spatially depending on the predominant form of available N (NH 4 + vs. NO 3 À ). Climatic decoupling of N accumulation and biological consumption (Ulrich 1983;Hornung and Reynolds 1995) may become more prevalent given predicted shifts in precipitation regimes and more extensive drought as a result of climate change (West et al 1994;Gregory et al 1997;Karl and Trenberth 2003). Knowledge of the role of rainfall patterns in N transformations and retention rates, as well as the effect of N transport on both terrestrial and aquatic ecosystems, will provide us with a better understanding of the spatial and temporal dynamics involved in N retention at the watershed scale.…”

Section: Discussionmentioning

confidence: 98%

Nitrogen Transport and Retention in an Arid Land Watershed: Influence of Storm Characteristics on Terrestrial–aquatic Linkages

2005

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Arid ecosystems experience prolonged dry periods, as well as storms that vary in size, intensity and frequency. As a result, nitrogen (N) retention and export patterns may be a function of individual storm characteristics. Our objective was to determine how seasonal patterns in rainfall as well as individual storm characteristics influence N transport and retention on terrestrial hill slopes in a Sonoran Desert watershed. Regression models indicated that variation in runoff ammonium (NH 4 + ) was best explained by antecedent conditions (cumulative seasonal rainfall, days since last storm) while variation in runoff nitrate (NO 3 À ) was best explained by single storm characteristics, primarily rain NO 3 À . Increases in runoff NO 3 À along overland surface flowpaths were balanced by decreases in NH 4 + during summer, with no change in dissolved inorganic nitrogen (DIN) concentration; a pattern consistent with nitrification. Nitrate increases along flowpaths were not as strong during winter storms. Results indicate that NH 4 + is transported from hillslopes to other parts of the catchment, including streams, and that nitrification occurs along surface flowpaths, particularly during summer storms. These findings suggest that the extent to which a receiving patch is supplied with NH 4 + or NO 3 À depends on the distance runoff has traveled (flowpath length) and the length of the antecedent dry period. The extent and configuration of fluvial reconnection amongst patches in the landscape following long drought periods likely determines the fate of available N, whether N is processed and retained in the terrestrial or in the aquatic component of the watershed, and the mechanisms involved. The nature of this fluvial reconnection is driven by the size, intensity and sequence of storms in space and time.

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Section: Discussionmentioning

confidence: 98%

Nitrogen Transport and Retention in an Arid Land Watershed: Influence of Storm Characteristics on Terrestrial–aquatic Linkages

2005

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“…The National Land and Water Resources Audit (2000) reported that 5.7 million ha have a high potential for the development of dryland salinity, and predicts this to rise to 17 million ha by 2050. Salts in soil cause osmotic stress, which can reduce crop yields (Lambers 2003), and cause environmental problems such as erosion and eutrophication of waterways (West et al 1994) and stress, or even kill, soil microorganisms (Wichern et al 2006a) and therefore affect nutrient cycling. Previously, it has been shown that high salinity causes osmotic stress and reduces microbial biomass (Tripathi et al 2006;Wichern et al 2006a), amino acid uptake and protein synthesis (Norbek and Blomberg 1998), and respiration (Gennari et al 2007;Laura 1974;Pathak and Rao 1998).…”

Section: Introductionmentioning

confidence: 99%

Response of microbial activity and community structure to decreasing soil osmotic and matric potential

2011

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Low soil water content (low matric potential) and salinity (low osmotic potential) occur frequently in soils, particularly in arid and semi-arid regions. Although the effect of low matric or low osmotic potential on soil microorganisms have been studied before, this is the first report which compares the effect of the two stresses on microbial activity and community structure. A sand and a sandy loam, differing in pore size distribution, nutrient content and microbial biomass and community structure, were used. For the osmotic stress experiment, salt (NaCl) was added to achieve osmotic potentials from −0.99 to −13.13 MPa (sand) and from −0.21 to 3.41 MPa (sandy loam) after which the soils were pre-incubated at optimal water content for 10d. For the matric stress experiment, soils were also preincubated at optimal water content for 10d, after which the water content was adjusted to give matric potentials from −0.03 and −1.68 MPa (sand) and from −0.10 to 1.46 MPa (sandy loam). After amendment with 2% (w/w) pea straw (C/N 26), soil respiration was measured over 14d. Osmotic potential decreased with decreasing soil water content, particularly in the sand. Soil respiration decreased with decreasing water potential (osmotic+matric). At a given water potential, respiration decreased to a greater extent in the matric stress experiment than in the osmotic stress experiment. Decreasing osmotic and matric potential reduced microbial biomass (sum of phospholipid fatty acids measured after 14 days) and changed microbial community structure: fungi were less tolerant to decreasing osmotic potential than bacteria, but more tolerant to decreasing water content. It is concluded that low matric potential may be more detrimental than a corresponding low osmotic potential at optimal soil water content. This is likely to be a consequence of the restricted diffusion of substrates and thus a reduced ability of the microbes to synthesise osmolytes to help maintain cell water content. The study also highlighted that it needs to be considered that decreasing soil water content concentrates the salts, hence microorganisms in dry soils are exposed to two stressors.

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“…While drylands are known to be among the most sensitive biomes to global change [54,55], there are many uncertainties surrounding the ecological consequences of such change on these ecosystems [2]. This is particularly evident when considering climate change impacts on BSCs, as only a handful of experimental studies have explicitly evaluated how future climatic conditions affect the performance, dynamics and functioning of their constituents [38][39][40]46,56,57].…”

Section: Introductionmentioning

confidence: 99%

Warming reduces the growth and diversity of biological soil crusts in a semi-arid environment: implications for ecosystem structure and functioning

Escolar

Martínez

Bowker

et al. 2012

Phil. Trans. R. Soc. B

127

136

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Biological soil crusts (BSCs) are key biotic components of dryland ecosystems worldwide that control many functional processes, including carbon and nitrogen cycling, soil stabilization and infiltration. Regardless of their ecological importance and prevalence in drylands, very few studies have explicitly evaluated how climate change will affect the structure and composition of BSCs, and the functioning of their constituents. Using a manipulative experiment conducted over 3 years in a semi-arid site from central Spain, we evaluated how the composition, structure and performance of lichen-dominated BSCs respond to a 2.48C increase in temperature, and to an approximately 30 per cent reduction of total annual rainfall. In areas with well-developed BSCs, warming promoted a significant decrease in the richness and diversity of the whole BSC community. This was accompanied by important compositional changes, as the cover of lichens suffered a substantial decrease with warming (from 70 to 40% on average), while that of mosses increased slightly (from 0.3 to 7% on average). The physiological performance of the BSC community, evaluated using chlorophyll fluorescence, increased with warming during the first year of the experiment, but did not respond to rainfall reduction. Our results indicate that ongoing climate change will strongly affect the diversity and composition of BSC communities, as well as their recovery after disturbances. The expected changes in richness and composition under warming could reduce or even reverse the positive effects of BSCs on important soil processes. Thus, these changes are likely to promote an overall reduction in ecosystem processes that sustain and control nutrient cycling, soil stabilization and water dynamics.

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Effects of climatic change on the edaphic features of arid and semiarid lands of western North America

Cited by 51 publications

References 72 publications

Nitrogen Transport and Retention in an Arid Land Watershed: Influence of Storm Characteristics on Terrestrial–aquatic Linkages

Nitrogen Transport and Retention in an Arid Land Watershed: Influence of Storm Characteristics on Terrestrial–aquatic Linkages

Response of microbial activity and community structure to decreasing soil osmotic and matric potential

Warming reduces the growth and diversity of biological soil crusts in a semi-arid environment: implications for ecosystem structure and functioning

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