Article
Environmental Sciences
Bethany L. Coulthard, Kevin J. Anchukaitis, Gregory T. Pederson, Edward Cook, Jeremy Littell, Dan J. Smith
Summary: Climate change has led to recent declines in mountain snowpack and earlier runoff, intensifying hydrological droughts in western North America. Current understanding of trends and variability in mountain snowpack is limited, highlighting the need for further research in this area.
ENVIRONMENTAL RESEARCH LETTERS
(2021)
Article
Environmental Sciences
K. Bailey, P. Szejner, Brandon Strange, R. K. Monson, Jia Hu
Summary: Through studying eight different Pinus ponderosa montane forests across a climate gradient in the southwestern U.S., researchers found that during a megadrought, trees rely less on summer rainwater and more on winter snowmelt as their primary water source. The early disappearance of snow during low snowpack years weakens the hydrologic connectivity within the soil profile and decreases the soil infiltration of summer rains. However, in years with higher snowpack, the longer-lasting snow enhances the hydrologic connectivity within the soil profile and allows for more infiltration of summer rains. These findings provide important insights into how forest tree water use is influenced by major seasonal climate systems during an extreme megadrought.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2023)
Article
Geosciences, Multidisciplinary
Junzhou Zhang, Xiaohua Gou, M. Ross Alexander, Jingqing Xia, Fang Wang, Fen Zhang, Zihong Man, Neil Pederson
Summary: Research on xylogenesis of Juniperus przewalskii Kom. on the northeastern Tibetan Plateau reveals that temperature is crucial for wood formation, with a daily mean temperature of 6.1 degrees C as the threshold for growth onset, and the end of xylogenesis is linked to summer drought conditions. Despite a slight lengthening of the growing season over the past six years, an increase in duration did not necessarily result in higher wood production, indicating that water availability, particularly early summer precipitation, plays a key role in wood production in the region.
Article
Geosciences, Multidisciplinary
Xiaodan Guan, Kaiwei Zhu, Xiaoqian Huang, Xinrui Zeng, Yongli He
Summary: The semi-arid regions of East Asia are influenced by both the monsoon and westerly winds, with wet years seeing an enhancement in both systems leading to more rainfall, while dry years experience a weakening of both resulting in less precipitation. The interaction between the monsoon and westerlies is dynamic, with the monsoon shifting westward in wet years and impacting rainfall distribution.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Agronomy
Hsin-Ju Li, Min-Hui Lo, Jehn-Yih Juang, Jonathan Wang, Cho-ying Huang
Summary: This study quantifies the diurnal fog occurrence in subtropical mountain cloud forests in northeast Taiwan using machine learning methods. The results show that fog is more abundant in mid-elevations, with pronounced seasonality and higher fog abundance in the afternoons and cold months. Machine learning can be an effective tool for monitoring the impact of climate change on cloud forests.
AGRICULTURAL AND FOREST METEOROLOGY
(2022)
Article
Geography, Physical
Jing Lei, Zhengguo Shi, Xiaoning Xie, Xinzhou Li
Summary: Based on climate model experiments, this study found that the precipitation during the Last Glacial Maximum (LGM) was significantly different from that of the preindustrial period in the terrestrial monsoon regions and arid regions of the Northern Hemisphere. The decrease in sea surface temperature and expansion of the ice sheet were the main contributors to lessening precipitation in the monsoon regions, while the decrease in precipitation in the arid regions can be mainly attributed to ice-sheet-induced albedo and topography changes.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2022)
Article
Multidisciplinary Sciences
Ranjini Ray, Atreyee Bhattacharya, Gaurav Arora, Kushank Bajaj, Keyle Horton, Shi Chen, Supriyo Chakraborty, Amir Bazaz
Summary: The study demonstrates that southern Indian SARs repeatedly experienced famines when annual rainfall reduced by about one standard deviation (1 SD) or more. The colonial-era famines in peninsular India were typically caused by fluctuations in precipitation within the normal range of regional rainfall variability, rather than extreme rainfall deficits.
SCIENTIFIC REPORTS
(2021)
Article
Environmental Sciences
Tyler J. Mitchell, Paul A. Knapp
Summary: Previous studies have focused on the relationship between total precipitation and tree radial growth in the southeastern USA. However, recent research suggests that specific precipitation event types and intensities affect longleaf pine radial growth differently. This study examines the climate-radial growth relationships of four pine species in the southeastern USA and finds that there are distinct temporal sensitivities among species and a consistent association between certain precipitation types and radial growth.
Article
Geography, Physical
Rupesh Dhyani, Mayank Shekhar, Rajesh Joshi, Amalava Bhattacharyya, Parminder S. Ranhotra, Ashish K. Pal, Shinny Thakur, Shyamal K. Nandi
Summary: This study presents a new reconstruction of relative humidity (RH) in the Himalayan region during the pre-monsoon months using tree-ring width data. They found a significant positive correlation between tree growth and pre-monsoon RH and identified a declining trend in RH over the past 35 years. The reliability of the reconstructed data was validated by comparing it with ERA-interim data and it was also found to be consistent with precipitation and temperature patterns in the region. Spectral analysis revealed periodicities linked to the El-Nino-Southern Oscillation.
QUATERNARY INTERNATIONAL
(2022)
Article
Environmental Sciences
Hushiar Hamarash, Rahel Hamad, Azad Rasul
Summary: This study determined the spatiotemporal distribution of meteorological drought in the semi-arid regions of Iran using TerraClimate data. The results showed that the majority of years experienced normal conditions, with occurrences of extreme drought. The significance of this study lies in the strong data validation it provides.
JOURNAL OF ARID LAND
(2022)
Article
Geography, Physical
Amani Al Abri, Noah P. Snyder, Sergio Fagherazzi
Summary: This study investigated the relationships among precipitation, vegetation, and morphological characteristics of watersheds on both sides of the Dhofar Mountains in southeastern Oman. The research found a correlation between vegetation and cloud cover, and highlighted how hypsometric curves and statistical moments can differentiate between wet and dry watersheds. The findings suggest a significant link between hydrology and morphology, especially when watersheds are aggregated in zones, with distinct groups identified based on their hydrological and morphological characteristics.
EARTH SURFACE PROCESSES AND LANDFORMS
(2021)
Article
Biodiversity Conservation
Magdalena Opala-Owczarek, Piotr Owczarek, Oimahmad Rahmonov, Lukasz Malarzewski, Feng Chen, Tadeusz Niedzwiedz
Summary: This study focuses on the dendrochronological and dendroclimatological characteristics of juniper trees in the Pamir-Alay mountains in Tajikistan. The results demonstrate that precipitation variability is the main climate factor affecting radial growth in this semi-arid region. However, the study also reveals divergent dendroclimatic responses between low- and high-elevation sites, where different limiting factors have a dominant role. The findings highlight the importance of selecting topographically differentiated sites for the reconstruction of climatic elements in Central Asia.
ECOLOGICAL INDICATORS
(2023)
Article
Multidisciplinary Sciences
Xiaodong Liu, Xiaoxun Xie, Zhengtang Guo, Zhi-Yong Yin, Guangshan Chen
Summary: This study investigates the orbital-scale precipitation isotope variations in arid Central Asia, monsoonal South Asia, and East Asia. The results show significant but asynchronous 23-kyr precession cycles in the delta O-18(p) variations in all three regions. The dominant mechanisms and physical processes involved in these variations differ among the regions.
NATIONAL SCIENCE REVIEW
(2022)
Article
Forestry
Chun-Yang Duan, Ming-Yong Li, Li-Dong Fang, Yu Cao, De-Dong Wu, Hui Liu, Qing Ye, Guang-You Hao
Summary: Quantifying inter-specific variations of tree resilience to drought is crucial for understanding forest functionality in water-limited regions. A study in northern China found significant inter-specific variations in radial growth rate, growth response to drought, and physiological characteristics among seven pine species. Species with higher hydraulic conductivity and photosynthetic capacity were more sensitive to drought stress, indicating a trade-off between hydraulic efficiency and safety across species.
Article
Meteorology & Atmospheric Sciences
Christa D. Peters-Lidard, David M. Mocko, Lu Su, Dennis P. Lettenmaier, Pierre Gentine, Michael Barlage
Summary: This article discusses the importance of modern drought monitoring, introduces the continuous improvement of land surface models and remote sensing technology, points out the application advantages of new drought indicators, and the role of dynamic vegetation phenology and groundwater in drought assessment.
BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY
(2021)
Editorial Material
Plant Sciences
Russell K. Monson, Paul Szejner, Soumaya Belmecheri, Kiyomi A. Morino, William E. Wright
AMERICAN JOURNAL OF BOTANY
(2018)
Article
Biodiversity Conservation
Paul Szejner, William E. Wright, Soumaya Belmecheri, David Meko, Steven W. Leavitt, James R. Ehleringer, Russell K. Monson
GLOBAL CHANGE BIOLOGY
(2018)
Article
Ecology
Paul Szejner, Soumaya Belmecheri, James R. Ehleringer, Russell K. Monson
Article
Plant Sciences
Paul Szejner, Timothy Clute, Erik Anderson, Michael N. Evans, Hu Jia
Article
Environmental Sciences
Guobao Xu, Xiaohong Liu, Weizhen Sun, Paul Szejner, Xiaomin Zeng, Kei Yoshimura, Valerie Trouet
ENVIRONMENTAL RESEARCH LETTERS
(2020)
Article
Ecology
Paul Szejner, Soumaya Belmecheri, Flurin Babst, William E. Wright, David C. Frank, Jia Hu, Russell K. Monson
Summary: Recent evidence has shown the emergence of a megadrought in southwestern North America since 2000. Trees near their arid range limit exhibit unique sensitivity to pre-megadrought conditions, particularly in key seasonal months such as winter and summer. This physiological sensitivity could potentially aid in the early detection of long-lasting droughts.
Article
Multidisciplinary Sciences
Steven A. Kannenberg, Avery W. Driscoll, Paul Szejner, William R. L. Anderegg, James R. Ehleringer
Summary: Globally, intrinsic water-use efficiency (iWUE) has shown a significant increase over the past century in line with rising atmospheric CO2 concentrations. Recent drying trends in the American Southwest have led to a rapid increase in iWUE in shrub species in the region, surpassing that of tree species. While a shift towards more water-efficient vegetation may benefit plant health, ongoing trends of lower plant density, diminished growth, and increasing vegetation mortality in the Southwest suggest that this increase in iWUE is unlikely to offset the negative impacts of aridification.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Ecology
Larissa Yocom, Kiona Ogle, Drew Peltier, Paul Szejner, Yao Liu, Russell K. Monson
Summary: Precipitation and temperature influence the seasonal and annual variability of tree growth in the southwestern United States, with trees exhibiting multi-year climate memory. Wetter sites show weaker influence of past precipitation but longer memory of climatic variability, while drier sites display shorter memory of long-term climate variability but greater sensitivity to past precipitation effects. There exist complex interactions between endogenous and exogenous effects in controlling climate memory in trees.
Article
Multidisciplinary Sciences
Antoine Cabon, Steven A. Kannenberg, Altaf Arain, Flurin Babst, Dennis Baldocchi, Soumaya Belmecheri, Nicolas Delpierre, Rossella Guerrieri, Justin T. Maxwell, Shawn McKenzie, Frederick C. Meinzer, David J. P. Moore, Christoforos Pappas, Adrian Rocha, Paul Szejner, Masahito Ueyama, Danielle Ulrich, Caroline Vincke, Steven L. Voelker, Jingshu Wei, David Woodruff, William R. L. Anderegg
Summary: Uncertainties in tree carbon allocation to growth limit projections of forest carbon sequestration and response to climate change. Our study reveals widespread decoupling between carbon assimilation and tree growth, driven by varying climatic sensitivities and tree species. Sink control over tree growth becomes more prominent with canopy closure, aridity, and decreasing temperatures.
Editorial Material
Forestry
Steven W. Leavitt, Paul Szejner
TREES-STRUCTURE AND FUNCTION
(2022)
Article
Multidisciplinary Sciences
Julian Cerano-Paredes, Paul Szejner, Genaro Gutierrez-Garcia, Rosalinda Cervantes-Martinez, Victor H. Cambron-Sandoval, Jose Villanueva-Diaz, Josue R. Estrada-Arellano, Osvaldo Franco-Ramos, Lorenzo Vazquez-Selem, Luis U. Castruita-Esparza
Summary: Tree rings have been widely used to reconstruct climatological variables worldwide. In recent years, there has been increasing interest in dendrochronology to extend the timeline of climate information and understand climate changes at different scales. This article aims to describe the basic steps of conducting tree-ring climate reconstruction and serve as a guide for newcomers and students in this field of research.
JOVE-JOURNAL OF VISUALIZED EXPERIMENTS
(2022)
Article
Ecology
Beatriz Arguelles-Marron, Jorge A. Meave, Isolda Luna-Vega, Doris B. Crispin-DelaCruz, Paul Szejner, Fressia N. Ames-Martinez, Ernesto C. Rodriguez-Ramirez
Summary: Climate and water availability drive adaptive variation and plasticity in the hydraulic architecture of TMCF tree species. This study evaluated the effects of temperature, precipitation, and evapotranspiration on oak species in a Mexican TMCF. The results showed that these species have high resilience and adaptability to drought events.
FUNCTIONAL ECOLOGY
(2023)
Article
Environmental Sciences
Rocio Urrutia-Jalabert, Jonathan Barichivich, Paul Szejner, Vicente Rozas, Antonio Lara
Summary: The forests in south-central Chile are experiencing a drying climate and a megadrought since 2010. This study found that the forests have become more efficient in water use, but the trees in the densest stand have a reduced adaptability to climate change. The research demonstrates that the forests in central Chile are not reducing their growth, mainly due to a shift towards using deeper water sources.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2023)
Article
Environmental Sciences
Yao Li, Xiaomin Zeng, Xiaohong Liu, Michael N. Evans, Guobao Xu, Paul Szejner, Ping Ni
Summary: The study on stable carbon and oxygen isotopes in Chinese pine trees shows that drought significantly affects tree growth, especially in the late growing season. Carbon isotopes record a stronger drought signal than oxygen isotopes, which is mainly reflected in the late growing season.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2023)
Article
Forestry
Guobao Xu, Xiaohong Liu, Jia Hu, Isabel Dorado-Linan, Mary Gagen, Paul Szejner, Tuo Chen, Valerie Trouet
Summary: This study reveals the effects of seasonal humidity and temperature on the stable isotopic variability of tree rings. The intra-annual delta O-18 variability is greater in wet years compared to dry years, while delta C-13 variability is lower. Process-based models show different capabilities in simulating the intra-annual stable isotopic variability in wet and dry years.