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Innovations in horse equipment during the early Middle Ages provided advantages to societies from the steppes, reshaping the social landscape of Eurasia. Comparatively little is known about the precise origin of these crucial advances, although the available evidence points to early adoption in East Asia. The authors present new archaeological discoveries from western and northern Mongolia, dating to the fourth and fifth centuries AD, including a wooden frame saddle with horse hide components from Urd Ulaan Uneet and an iron stirrup from Khukh Nuur. Together, these finds suggest that Mongolian groups were early adopters of stirrups and saddles, facilitating the expansion of nomadic hegemony across Eurasia and shaping the conduct of medieval mounted warfare. Keywords: Mongolia, Middle Ages, horse riding, stirrup, saddle, Introduction Across Eurasia, the development of sophisticated cavalry had tremendous consequences for ancient societies. Beginning with the domestication of the horse and the subsequent invention of the chariot in the [...]

The estimation of year of germination based on saguaro cactus (Carnegiea gigantea) growth rates is essential for understanding population dynamics. To assess how habitat and climate interact to influence growth rate, we resurveyed 614 saguaro cacti on 11 historical study plots in Saguaro National Park (SNP), including the plots where classic saguaro age–height models were developed. We classified plots into four groups based on their topographic position (bajada or rocky slope) and park district (east or west), compared actual to predicted height distributions, assessed the distributions for (dis)similarity using the Jensen-Shannon distance, tested for significance with Fisher's exact test, and calculated growth rate adjustment factors with the Drezner method. We found that saguaro growth rates slowed significantly for three of the four combinations of topographic position and district from 1975 to 2014. Observed height class distributions differed significantly from the predicted for rocky slopes but not for bajada habitats. Variability in saguaro growth rates among populations in different habitats over a short distance through time may have scientific and ecological implications, including decreasing the accuracy of population age calculations and delaying the onset of flowering and branching. We encourage SNP to continue the ongoing long-term studies to quantify the resulting effects of climate change and to incorporate the results of this study into interpretative programs and literature. [ABSTRACT FROM AUTHOR]

Abstract: The long‐lived columnar saguaro cactus (Carnegiea gigantea) is among the most studied plants in the world. Long‐term studies have shown saguaro establishment to be generally episodic and strongly influenced by precipitation and temperature. Water limitation through lower‐than‐average seasonal rainfall and elevated temperatures increasing evaporative loss can reduce survivorship of recent germinates. Thus, multi‐year, extended drought could cause populations to decline as older saguaros die without replacement. Previous studies have related establishment to temporal variation in rainfall, but most studies have been on non‐randomized plots in ideal habitat and thus might not have captured the full variability within the local area. We studied how saguaro establishment varied in space and which habitat features may buffer responses to drought on 36 4‐ha plots located randomly across an elevation gradient, including substantial replication in landscape position (bajada, foothills, and slopes) in the two disjunct districts of Saguaro National Park in southern Arizona, USA. Recent, severe drought coincided with drastic declines in saguaro establishment across this ~25,000‐ha area. Establishment patterns derived from the park‐wide data set was strongly correlated with drought, but the Park's two districts and diversity of plots demonstrated substantially different population outcomes. Saguaro establishment was best explained by the interaction of drought and habitat type; establishment in bajada and foothill plots dropped to near‐zero under the most severe periods of water limitation but remained higher in slope plots during the same time span. Combined with saguaro density estimates, these data suggest that the most suitable habitat type for saguaro establishment shifted to higher elevations during the time span of the recent drought. These results place into context the extent to which historical patterns of demography provide insight into future population dynamics in a changing climate and reveal the importance of understanding dynamics across the distribution of possible local habitat types with response to variation in weather. [ABSTRACT FROM AUTHOR]