Annual precipitation in the yellowstone National Park region since AD 1173

AbstractCores and cross sections from 133 limber pine (Pinus flexilis James) and Douglas fir (Pseudotsuga menziesii (Mirbel) Franco) at four sites were used to estimate annual (July to June) precipitation in the Yellowstone National Park region for the period from AD 1173 to 1998. Examination of the long-term record shows that the early 20th century was markedly wet compared to the previous 700 yr. Extreme wet and dry years within the instrumental period fall within the range of past variability, and the magnitude of the worst-case droughts of the 20th century (AD 1930s and 1950s) was likely equaled or exceeded on numerous occasions before AD 1900. Spectral analysis showed significant decadal to multidecadal precipitation variability. At times this lower frequency variability produces strong regime-like behavior in regional precipitation, with the potential for rapid, high-amplitude switching between predominately wet and predominately dry conditions. Over multiple time scales, strong Yellowstone region precipitation anomalies were almost always associated with spatially extensive events spanning various combinations of the central and southern U.S. Rockies, the northern U.S.–Southern Canadian Rockies and the Pacific Northwest.

Download Full-text

Conifer Establishment and Encroachment on Subalpine Meadows around Mt. Baker, WA, USA

Forests ◽

10.3390/f12101390 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1390

Author(s):

Ben Hagedorn ◽

Aquila Flower

Keyword(s):

20Th Century ◽

Pacific Northwest ◽

Cross Sections ◽

Seedling Establishment ◽

Strongly Correlated ◽

Subalpine Meadows ◽

Mountainous Regions ◽

Conifer Encroachment ◽

The Pacific ◽

Conifer Seedling

The subalpine ecotone is experiencing significant changes in habitat availability and connectivity as a result of climate change. The conversion of meadow habitats to forests has been observed in many mountainous regions. Rates of conifer encroachment into meadows appears to have increased in the 20th century, but the patterns of conifer establishment seem highly variable over both space and time. To understand how and why these changes vary temporally and spatially in the Pacific Northwest, we collected cross-sections and whorl counts from conifers along four transects in subalpine meadows around Mt. Baker, Washington. We quantified the relationships between temporal patterns of conifer establishment and a suite of climate variables, and between spatial patterns of conifer density and microsite characteristics. Our results show that establishment occurred in pulses throughout the 20th century, with greater establishment on drier sites during periods of greater precipitation, and greater establishment on wetter sites during periods of higher temperatures. We found that April precipitation and September temperature are particularly strongly correlated with establishment rates, suggesting that the best conditions for conifer seedling establishment occur in years with the warmth and soil moisture needed for the growing season to start earlier or last longer. Within individual meadows, conifer seedling establishment was greater on convex surfaces and in areas with a higher percentage of Vaccinium cover. Our findings at Mt. Baker show that periods of conifer establishment occurred somewhat synchronously across multiple mountains in the region, but we also identified distinct spatial and temporal differences linked to local site conditions.

Download Full-text

Understanding hydroclimate processes in the Murray-Darling Basin for natural resources management

Hydrology and Earth System Sciences ◽

10.5194/hess-16-2049-2012 ◽

2012 ◽

Vol 16 (7) ◽

pp. 2049-2068 ◽

Cited By ~ 65

Author(s):

A. J. E. Gallant ◽

A. S. Kiem ◽

D. C. Verdon-Kidd ◽

R. C. Stone ◽

D. J. Karoly

Keyword(s):

Time Scales ◽

Natural Resource ◽

Multiple Time Scales ◽

Small Scale ◽

Multiple Time ◽

Driving Mechanisms ◽

Murray Darling Basin ◽

Dry Conditions ◽

Natural Resource Managers ◽

Instrumental Records

Abstract. Isolating the causes of extreme variations or changes in the hydroclimate is difficult due to the complexities of the driving mechanisms, but it is crucial for effective natural resource management. In Australia's Murray-Darling Basin (MDB), ocean-atmosphere processes causing hydroclimatic variations occur on time scales from days to centuries, all are important, and none are likely to act in isolation. Instead, interactions between all hydroclimatic drivers, on multiple time scales, are likely to have caused the variations observed in MDB instrumental records. A simplified framework is presented to assist natural resource managers in identifying the potential causes of hydroclimatic anomalies. The framework condenses an event into its fundamental elements, including its spatial and temporal signal and small-scale evolution. The climatic processes that are potentially responsible are then examined to determine possible causes. The framework was applied to a period of prolonged and severe dry conditions occurring in the southern MDB from 1997–2010, providing insights into possible causal mechanisms that are consistent with recent studies. The framework also assists in identifying uncertainties and gaps in our understanding that need to be addressed.

Download Full-text

Understanding climate processes in the Murray-Darling Basin: utility and limitations for natural resources management

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-8-7873-2011 ◽

2011 ◽

Vol 8 (4) ◽

pp. 7873-7918 ◽

Cited By ~ 2

Author(s):

A. J. E. Gallant ◽

A. S. Kiem ◽

D. C. Verdon-Kidd ◽

R. C. Stone ◽

D. J. Karoly

Keyword(s):

Natural Resources ◽

Time Scales ◽

Natural Resources Management ◽

Multiple Time Scales ◽

Multiple Time ◽

Resources Management ◽

Murray Darling Basin ◽

Decadal Scale ◽

Dry Conditions ◽

Instrumental Records

Abstract. Ocean-atmosphere processes causing variations in the climate of Australia's Murray-Darling Basin (MDB) occur on time scales from days to centuries, all are important, and none are likely to act in isolation. Instead, interactions between all hydroclimatic drivers, on multiple time scales, are likely to have caused the variations observed in MDB instrumental records. The source and relative importance of each climate driver varies due to the geographic spread of the Basin from the subtropics to the middle latitudes. Such differences were highlighted during the period from 1997–2010 when the southern MDB experienced prolonged and severe dry conditions, while decadal-scale rainfall in the northern MDB remained close to normal. Although recent studies have provided insights into possible mechanisms, the cause of this recent drying is still uncertain. To this end, this paper addresses the current state of knowledge about the processes causing climate variations in the MDB and the utility and limitations of this knowledge for natural resources management.

Download Full-text

Climate change and social vicissitudes in China over the past two millennia

Quaternary Research ◽

10.1016/j.yqres.2016.07.003 ◽

2016 ◽

Vol 86 (2) ◽

pp. 133-143 ◽

Cited By ~ 17

Author(s):

Jun Yin ◽

Yun Su ◽

Xiuqi Fang

Keyword(s):

Climate Change ◽

Semantic Analysis ◽

Multiple Time Scales ◽

Multiple Time ◽

Chinese History ◽

High Resolution Data ◽

The Past ◽

The Social ◽

Dry Conditions

AbstractThe relation between climate change and historical rhythms has long been discussed. However, this type of study still faces the lack of high-resolution data concerning long-term socio-economic processes. In this study, we collected 1586 items of direct and proffered evidence from 29 Chinese history books. We used semantic analysis to reconstruct a quantitative series of the social vicissitudes of the past 2000 yr with a 10-yr resolution to express the phase transition of the social vicissitudes of the dynasties in China. Our reconstruction demonstrates that social vicissitudes have clear cyclical features on multiple time scales. Analysis of the association of social rise and fall with climate change indicates that temperature displayed more significant effects on social vicissitudes in the long term, while precipitation displayed more significant effects on the social vicissitudes in the short term. There are great overlaps between social and climatic variables around the predominant or periodic bands. Social rise mostly occurred in the centennial-scale warm periods, whereas social decline mostly occurred in the centennial-scale cold periods. Under warm-wet conditions, social rise occurred over 57% of the time; under cold-dry conditions, the social decline occurred over 66% of the time.

Download Full-text

Ultrastructural Localization of Phycocyanin in the Acidophilic, Thermophilic Alga, Cyanidium Caldarium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072757 ◽

1973 ◽

Vol 31 ◽

pp. 462-463

Author(s):

M. R. Edwards ◽

J. D. Mainwaring

Keyword(s):

Yellowstone National Park ◽

National Park ◽

Ultrastructural Localization ◽

Review Of Literature ◽

Cyanidium Caldarium ◽

Taxonomic Rank ◽

Thin Sections ◽

Standard Methods ◽

Laboratory Cultures

Although the general ultrastructure of Cyanidium caldarium, an acidophilic, thermophilic alga of questionable taxonomic rank, has been extensively studied (see review of literature in reference 1), some peculiar ultrastructural features of the chloroplast of this alga have not been noted by other investigators.Cells were collected and prepared for thin sections at the Yellowstone National Park and were also grown in laboratory cultures (45-52°C; pH 2-5). Fixation (glutaraldehyde-osmium), dehydration (ethanol), and embedding (Epon 812) were accomplished by standard methods. Replicas of frozenfracture d- etched cells were obtained in a Balzers apparatus. In addition, cells were examined after disruption in a French Press.

Download Full-text