Transpiration drivers of high-elevation five-needle pines (Pinus longaeva and Pinus flexilis) in sky-island ecosystems of the North American Great Basin

2020 ◽  
Vol 739 ◽  
pp. 139861
Author(s):  
Xinsheng Liu ◽  
Franco Biondi
1973 ◽  
Vol 3 (4) ◽  
pp. 632-660 ◽  
Author(s):  
Valmore C. LaMarche

AbstractRemains of dead bristlecone pine (Pinus longaeva Bailey) are found at altitudes up to 150 m above present treeline in the White Mountains. Standing snags and remnants in two study areas were mapped and sampled for dating by tree-ring and radiocarbon methods. The oldest remnants represent trees established more than 7400 y.a. Experimental and empirical evidence indicates that the position of the treeline is closely related to warm-season temperatures, but that precipitation may also be important in at least one of the areas. The upper treeline was at high levels in both areas until after about 2200 B.C., indicating warm-season temperatures about 3.5°F higher than those of the past few hundred years. However, the record is incomplete, relative warmth may have been maintained until at least 1500 B.C. Cooler and wetter conditions are indicated for the period 1500 B.C.-500 B.C., followed by a period of cool but drier climate. A major treeline decline occurred between about A.D. 1100 and A.D. 1500, probably reflecting onset of cold and dry conditions. High reproduction rates and establishment of scattered seedlings at high altitudes within the past 100 yr represents an incipient treeline advance, which reflected a general climatic warming beginning in the mid-19th century that has lasted until recent decades in the western United States. This evidence for climatic variation is broadly consistent with the record of Neoglacial advances in the North American Cordillera, and supports Antevs' concept of a warm “altithermal age” in the Great Basin.


2021 ◽  
Author(s):  
Cameron de Wet ◽  
Jessica Oster ◽  
Daniel Ibarra ◽  
Bryce Belanger

<p>The Last Interglacial (LIG) period (~129,000–116,000 years BP) and the mid-Holocene (MH) (~6,000 years BP) are the two most recent intervals with temperatures comparable to low emissions scenarios for the end of the 21<sup>st</sup> century. During the LIG and the MH differences in the seasonal and latitudinal distribution of insolation led to enhanced northern hemisphere high-latitude warmth relative to the pre-industrial, despite similar greenhouse gas concentrations, marking these intervals as potentially useful analogs for future change in regions like North America. Further, the inclusion of both LIG (127 ka) and MH (6 ka) experiments in the CMIP6-PMIP4 effort provides an opportunity to better understand the regional hydroclimate responses to radiative forcing during these two intervals. The dense coverage of paleoclimate proxy records for North America during the MH (N=260 sites) reveals a pattern of relative aridity in the Pacific Northwest and Western Canada and wetness in the southern Great Basin and Mexico. However, the seasonality and driving mechanisms of rainfall patterns across the continent remain poorly understood. Our understanding of terrestrial hydroclimate in North America during the LIG is more limited (N=39 sites), largely because the LIG is beyond the range of radiocarbon dating.</p><p>Here we present spatial comparisons between output from 14 PMIP4 global circulation models and LIG and MH networks of moisture-sensitive proxies compiled for the North American continent. We utilize two statistical measures of agreement – weighted Cohen’s Kappa and Gwet’s AC2 – to assess the degree of categorical agreement between moisture patterns produced by the models and the proxy networks for each time-slice. PMIP4 models produce variable precipitation anomalies relative to the pre-industrial for both the LIG and MH experiments, often disagreeing on both the sign and magnitude of precipitation changes across much of North America. The models showing the best agreement with the proxy network are similar but not identical for the two measures, with Gwet’s AC2 values tending to be larger than Cohen’s Kappa values for all models. This pattern is enhanced for the much larger MH proxy network and is likely related to the fact that Gwet’s AC2 is a more predictable statistic in the presence of high agreement. Overall agreement is lower for the mid-Holocene than for the LIG, reflecting smaller MH rainfall anomalies in the models. The models with the highest agreement scores during the LIG produce aridity in the Rocky Mountains and Pacific Northwest and wetness in Alaska, the Yukon, the Great Basin, and parts of the Mid-West and Eastern US, although spatial coverage of the proxies in these latter two regions is poor. The models with the highest agreement score for the mid-Holocene tend to produce aridity across Canada and the northern US with dry conditions extending down the US Pacific coast and increased wetness in the American Southeast and across the North American Monsoon region. Our analyses help elucidate the driving mechanisms of rainfall patterns during past warm states and can inform which models may be the most useful for predictions of near-future hydroclimate change across North America.</p>


Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 900
Author(s):  
Mackenzie Kilpatrick ◽  
Franco Biondi

Information on wildfire impacts and ecosystem responses is relatively sparse in the Great Basin of North America, where subalpine ecosystems are generally dominated by five-needle pines. We analyzed existing vegetation, with an emphasis on regeneration following the year 2000 Phillips Ranch Fire, at a sky-island site in the Snake Range of eastern Nevada. Our main objective was to compare bristlecone pine (Pinus longaeva; PILO) post-fire establishment and survival to that of the co-occurring dominant conifers limber pine (Pinus flexilis; PIFL) and Engelmann spruce (Picea engelmannii; PIEN) in connection with site characteristics. Field data were collected in 40 circular 0.1 ha plots (17.8 m radius) randomly located using GIS so that half of them were inside (“burned”) and half were outside (“unburned”) the 2000 fire boundary. While evidence of previous burns was also found, we focused on impacts from the Phillips Ranch Fire. Mean total basal area, including live and dead stems, was not significantly different between plots inside the burn and plots outside the fire perimeter, but the live basal area was significantly less in the former than in the latter. Wildfire impacts did not limit regeneration, and indeed bristlecone seedlings and saplings were more abundant in plots inside the 2000 fire perimeter than in those outside of it. PILO regeneration, especially saplings, was more abundant than PIFL and PCEN combined, indicating that PILO can competitively regenerate under modern climatic conditions. Surviving PILO regeneration in burned plots was also taller than that of PIFL. By contrast, PCEN was nearly absent in the plots that had been impacted by fire. Additional research should explicitly address how climatic changes and disturbance processes may interact in shaping future vegetation dynamics.


Author(s):  
David Hurst Thomas ◽  
Jessica R. Bean ◽  
Gregory R. Burns ◽  
Timothy W. Canaday ◽  
David Alan Charlet ◽  
...  

The Central Mountains Archaic began with the arrival of foraging populations in the Intermountain West about 6000 years ago. This migration coincided with the "extremely dramatic" winter-wet event of 4350 cal b.c. and the arrival of piñon pine forests in the central Great Basin. Human foragers likely played a significant role in the rapid spread of piñon across the central and northeastern Great Basin. Logistic hunters exploited local bighorn populations, sometimes serviced by hunting camps (the "man caves" such as Gatecliff Shelter, Triple T Shelter, and several others) and they staged communal pronghorn drives at lower elevations. As climate cooled and became more moist, logistic bighorn hunting gradually shifted downslope, then apparently faded away about 1000 cal b.c. Communal pronghorn driving persisted into the historic era in the central Great Basin. This volume, the first in the Alta Toquima trilogy, describes and analyzes more than 100 alpine hunting features on the Mt. Jefferson tablelands. High-elevation, logistical bighorn hunting virtually disappeared across the central Great Basin with the onset of the Late Holocene Dry Period (about 750-850 cal b.c.), giving way to an alpine residential pattern at Alta Toquima (26NY920) and elsewhere on Mt. Jefferson. Situated at almost exactly 11,000 ft (3352 m) above sea level, Alta Toquima was sited on the south summit of Mt. Jefferson (the third-highest spot in the state of Nevada), where at least 31 residential stone structures were emplaced along this steep, east-facing slope. When first recorded in 1978, Alta Toquima was the highest American Indian village site known in the Northern Hemisphere. This volume discusses the material culture, plant macrofossils, vertebrate fauna, and radiocarbon dating for Alta Toquima. Bayesian analysis of 95 14C dates documents an initial occupation of Alta Toquima at 1370-790 cal b.c., with the sporadic settlements persisting until immediately before European contact. These alpine residences are the most dramatic examples of the intensified provisioning strategies that began in the Central Mountains Archaic about 3000 years ago, broadening the diet breadth to include plant and animal resources previously considered too costly. The oldest summertime residence at Alta Toquima correlates with the onset of Late Holocene Dry Period (LHDP) aridity (~750 cal b.c.), and these houses were episodically occupied only during the driest intervals throughout the next 1500 dramatic years of abrupt climate change. During the intervening wetter stretches, Alta Toquima was abandoned in favor of subalpine basecamps. This sequenced intensification predated the arrival of bow technology in the central Great Basin by more than a millennium. Exactly the opposite sequencing took place a few miles to the north, when Gatecliff Shelter was abandoned during LHDP aridity--precisely when the first summertime settlements appeared at Alta Toquima. This pattern reversed again when lowland habitats became sufficiently well watered to again support summertime patches of seeds and geophytes (~150 cal b.c.-cal a.d. 100). Alta Toquima families responded by abandoning (temporarily) their alpine summertime camps to repurpose former "man caves" like Gatecliff and Triple T shelters into family settlements. The Monitor Valley sequence documents several syncopated lowland-alpine, wet-dry reversals, reflecting an adaptive diversity that spanned more than two millennia. The drought terminating cal a.d. 1150 devastated much of the western Great Basin and American Southwest, but its impact was less severe in central Nevada. Although subalpine sites were again abandoned during the drought buildup that peaked in the mid-12th century, summertime occupation of Alta Toquima became more commonplace, although it increased notably during the ~cal a.d. 1200-1400 aridity and persisted throughout the Little Ice Age.


2020 ◽  
Vol 243 ◽  
pp. 108409 ◽  
Author(s):  
Peter S. Coates ◽  
Shawn T. O'Neil ◽  
Brianne E. Brussee ◽  
Mark A. Ricca ◽  
Pat J. Jackson ◽  
...  

2020 ◽  
Vol 85 (4) ◽  
pp. 715-736
Author(s):  
B. Sunday Eiselt

Documenting variability in the archaeological record is critical to our understanding human fishing adaptations in the North American Great Basin over time. Unfortunately, in the absence of robust middle range techniques for interpreting fishbone assemblages, many studies have been limited in their capacity to engage in theoretical discussions of the role of fishing in forager subsistence regimes. The Northern Paiute in Oregon and Nevada exploited seasonally aggregated tui chub (Siphateles bicolor) through mass-harvesting techniques using nets and baskets. This article integrates experimental studies with ethnographic and archaeological data to infer the types of fishing gear that were used from the reconstructed sizes of tui chub remains. The mean size of fish assemblages is compared to the coefficient of variation to identify fishing techniques based on the size parameters of gear types, and a technology investment model is used to assess regional variations in commitments to fishing in open lake and marshland settings. Results are compared to tui chub assemblages from two protohistoric archaeological sites in eastern Oregon, revealing two distinctive fishing strategies with general implications for the organization of labor by hunter-gatherer fisherfolk.


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