Soil drying and wetting cycles can produce pulses of nitric oxide (NO) and nitrous oxide (N2O) emissions with substantial effects on both regional air quality and Earth’s climate. While pulsed production of N emissions is ubiquitous across ecosystems, the processes governing pulse magnitude and timing remain unclear. We studied the processes producing pulsed NO and N2O emissions at two contrasting drylands, desert and chaparral, where despite the hot and dry conditions known to limit biological processes, some of the highest NO and N2O flux rates have been measured. We measured N2O and NO emissions every 30 min for 24 h after wetting soils with isotopically-enriched nitrate and ammonium solutions to determine production pathways and their timing. Nitrate was reduced to N2O within 15 min of wetting, with emissions exceeding 1000 ng N–N2O m−2 s−1 and returning to background levels within four hours, but the pulse magnitude did not increase in proportion to the amount of ammonium or nitrate added. In contrast to N2O, NO was emitted over 24 h and increased in proportion to ammonium addition, exceeding 600 ng N–NO m−2 s−1 in desert and chaparral soils. Isotope tracers suggest that both ammonia oxidation and nitrate reduction produced NO. Taken together, our measurements demonstrate that nitrate can be reduced within minutes of wetting summer-dry desert soils to produce large N2O emission pulses and that multiple processes contribute to long-lasting NO emissions. These mechanisms represent substantial pathways of ecosystem N loss that also contribute to regional air quality and global climate dynamics.

ABSTRACT. Hunter-fisher-gatherer (HFG) variability has received a lot of attention. We review the key developments in the theories of variability, which have usually resulted in binary classifications. We argue that a range of variation based on the degree of territorial ownership is preferable to these classifications. Hunter-fisher-gatherers of the world's northern coasts have only been partially explored in this way with regard to variability. A major reason for this is that such coastal groups use boats, so normative models of inland terrestrial foraging are not immediately applicable. We suggest that the Saxe-Goldstein hypothesis, the cautious linking of territoriality to funerary behaviour, may be a useful avenue to explore. Much work has been done by scholars of the northern coasts on boats and maritime transport, and some conclusions could be extrapolated to regions farther south.Key words: hunter-fisher-gatherers; variability; foragers; collectors delayed return; Saxe-Goldstein hypothesis; cemetery; mobility RÉSUMÉ. La variabilité caractérisant les chasseurs-pêcheurs-cueilleurs (CPC) reçoit beaucoup d'attention. Nous passons en revue les principaux développements en ce qui a trait aux théories de la variabilité, qui se traduisent habituellement par des classifications binaires. Nous soutenons qu'une plage de variations fondée sur le degré de propriété territoriale est préférable à ces classifications. La variabilité caractérisant les chasseurs-pêcheurs-cueilleurs des côtes nord de la planète n'a été étudiée qu'en partie. Cela s'explique majoritairement par le fait que ces groupes côtiers se servent d'embarcations, si bien que les modèles normatifs de recherche de nourriture à l'intérieur des terres ne sont pas immédiatement applicables. Nous suggérons que l'hypothèse de Saxe-Goldstein, soit le lien prudent entre la territorialité et le comportement funéraire, pourrait présenter une piste valant la peine d'être explorée. Les spécialistes des côtes nord ont beaucoup étudié le transport maritime et le transport au moyen d'embarcations, si bien qu'il pourrait être possible d'extrapoler certaines conclusions quant aux régions situées plus au sud.

Warming-induced changes in precipitation regimes, coupled with anthropogenically enhanced nitrogen (N) deposition, are likely to increase the prevalence, duration, and magnitude of soil respiration pulses following wetting via interactions among temperature and carbon (C) and N availability. Quantifying the importance of these interactive controls on soil respiration is a key challenge as pulses can be

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The term “pigmy flint” was coined in 1895 and frequently used to describe small flint implements, many of them microliths, in British and Irish archaeology during the earliest decades of the 20th century. It was briefly adopted in France over a decade later to describe the same tools, translated as “silex pygmée”, the simultaneous emergence of the French term “microlithique” saw the latter become more widely used, however. The Anglicised “microlith” was not commonly incorporated into British archaeological terminology until the mid-1920s. The international interplay in nomenclature and the changing nature of the terminology that was used to describe such “very small implements of flint” are mirrored by the different attitudes of early archaeologists to these tools. They were dismissed by some and marvelled at by others. Moreover, the definitions that surround these terms are embedded within the problematised acceptance of the “Mesolithic” as a distinct chronological entity. The recognition of morphologically similar “pigmies” across the world sparked questions of migration, function, and chronology – in its broadest culture-historical sense – thus shaping the way in which this microlithic technology and its association with the Mesolithic came to be understood by early archaeologists in Western Europe.