scholarly journals Early summer hydroclimatic signals are captured well by tree-ring earlywood width in the eastern Qinling Mountains, central China

2019 ◽  
Vol 15 (3) ◽  
pp. 1113-1131 ◽  
Author(s):  
Yesi Zhao ◽  
Jiangfeng Shi ◽  
Shiyuan Shi ◽  
Xiaoqi Ma ◽  
Weijie Zhang ◽  
...  

Abstract. In the humid and semi-humid regions of China, tree-ring-width (TRW) chronologies offer limited moisture-related climatic information. To gather additional climatic information, it would be interesting to explore the potential of the intra-annul tree-ring-width indices (i.e., the earlywood width, EWW, and latewood width, LWW). To achieve this purpose, TRW, EWW, and LWW were measured from the tree-ring samples of Pinus tabuliformis originating from the semi-humid eastern Qinling Mountains, central China. Standard (STD) and signal-free (SSF) chronologies of all parameters were created using these detrending methods including (1) negative exponential functions combined with linear regression with negative (or zero) slope (NELR), (2) cubic smoothing splines with a 50 % frequency cutoff at 67 % of the series length (SP67), and (3) age-dependent splines with an initial stiffness of 50 years (SPA50). The results showed that EWW chronologies were significantly negatively correlated with temperature but positively correlated with precipitation and soil moisture conditions during the current early-growing season. By contrast, LWW and TRW chronologies had weaker relationships with these climatic factors. The strongest climatic signal was detected for the EWW STD chronology detrended with the NELR method, explaining 50 % of the variance in the May–July self-calibrated Palmer Drought Severity Index (MJJ scPDSI) during the instrumental period 1953–2005. Based on this relationship, the MJJ scPDSI was reconstructed back to 1868 using a linear regression function. The reconstruction was validated by comparison with other hydroclimatic reconstructions and historical document records from adjacent regions. Our results highlight the potential of intra-annual tree-ring indices for reconstructing seasonal hydroclimatic variations in humid and semi-humid regions of China. Furthermore, our reconstruction exhibits a strong in-phase relationship with a newly proposed East Asian summer monsoon index (EASMI) before the 1940s on the decadal and longer timescales, which may be due to the positive response of the local precipitation to EASMI. Nonetheless, the cause for the weakened relationship after the 1940s is complex, and cannot be solely attributed to the changing impacts of precipitation and temperature.

2018 ◽  
Author(s):  
Yesi Zhao ◽  
Jiangfeng Shi ◽  
Shiyuan Shi ◽  
Xiaoqi Ma ◽  
Weijie Zhang ◽  
...  

Abstract. Historical hydroclimate records derived from tree-ring parameters are scarce in the core region of East Asian Summer Monsoon (EASM) in China, limiting our understanding of the inter-decadal hydroclimate variability of this region and its possible connections with the EASM. In this study, standard chronologies of total tree-ring width (TRW), earlywood width (EWW), and latewood width (LWW) were created using tree-ring samples of Pinus tabulaeformis in the eastern Qinling Mountains, Central China. The strongest growth-climate relationship was found between EWW and May–July self-calibrated Palmer Drought Severity Index (MJJ scPDSI). Therefore, a linear regression model, which explained 50.3 % of the variance in MJJ scPDSI (1951–2005), was developed to estimate the past MJJ scPDSI variations using EWW. The time series of MJJ scPDSI was extended back to the year 1866, and validated by independent hydroclimate series from nearby regions. Before the mid-1950s, the variations of MJJ scPDSI were in-phase with those of EASM intensity on decadal and longer timescales, suggesting that wet conditions would occur in the eastern Qinling Mountains when EASM was strengthened. Since the mid-1950s, however, the relationship has been out-of-phase. This phase change may be associated with an intensified dipole pattern of EASM precipitation.


2021 ◽  
Vol 8 (7) ◽  
pp. 201259
Author(s):  
Hongliang Gu ◽  
Jian Wang ◽  
Chao Lei ◽  
Lijuan Ma

This study addressed the effects of climate drivers on the tree-ring width (TRW) parameters (total ring width (TR), earlywood width (EW) and latewood width (LW)) and the total ring δ 13 C series of different wood components (whole wood, α-cellulose and holocelluose) from Masson pine in subtropical China. Pairwise correlation coefficients between three ring width parameters were statistically significant. EW and LW did not reveal much stronger climate sensitivity rather than TR. This indicated that the use of intra-annual ring width has little benefit in extracting more climate information. The mean δ 13 C series of the three components of the total ring had the strongest climate response to the July–September relative humidity ( r = −0.792 (whole wood), −0.758 (holocellulose) and −0.769 (α-cellulose)). There are no significant differences in the dendroclimatic relationships of the δ 13 C series of different wood components. Through both stationary temporal and spatial-statistical perspectives, the moisture drivers (summer/autumn) had a significant impact on three ring width parameters and three components of Masson pine. Overall, the radial growth and the δ 13 C series showed different responses to the same climate drivers during the same period. Moreover, the R-squared values of the strongest climate-proxy correlation coefficients were smaller than 50% for TRW. Consequently, the δ 13 C series of Masson pine may be a more representative climate proxy than TRW parameters for dendroclimatology in subtropical China.


2021 ◽  
Vol 303 ◽  
pp. 108394
Author(s):  
Nathsuda Pumijumnong ◽  
Piyarat Songtrirat ◽  
Supaporn Buajan ◽  
Sineenart Preechamart ◽  
Uthai Chareonwong ◽  
...  

2010 ◽  
Vol 29 (17-18) ◽  
pp. 2111-2122 ◽  
Author(s):  
X. Shao ◽  
Y. Xu ◽  
Z.-Y. Yin ◽  
E. Liang ◽  
H. Zhu ◽  
...  

2017 ◽  
Vol 41 (4) ◽  
pp. 478-495 ◽  
Author(s):  
UK Thapa ◽  
S St. George ◽  
DK Kharal ◽  
NP Gaire

The climate of Nepal has changed rapidly over the recent decades, but most instrumental records of weather and hydrology only extend back to the 1980s. Tree rings can provide a longer perspective on recent environmental changes, and since the early 2000s, a new round of field initiatives by international researchers and Nepali scientists have more than doubled the size of the country’s tree-ring network. In this paper, we present a comprehensive analysis of the current tree-ring width network for Nepal, and use this network to estimate changes in forest growth nation-wide during the last four centuries. Ring-width chronologies in Nepal have been developed from 11 tree species, and half of the records span at least 290 years. The Nepal tree-ring width network provides a robust estimate of annual forest growth over roughly the last four centuries, but prior to this point, our mean ring-width composite fluctuates wildly due to low sample replication. Over the last four centuries, two major events are prominent in the all-Nepal composite: (i) a prolonged and widespread growth suppression during the early 1800s; and (ii) heightened growth during the most recent decade. The early 19th century decline in tree growth coincides with two major Indonesian eruptions, and suggests that short-term disturbances related to climate extremes can exert a lasting influence on the vigor of Nepal’s forests. Growth increases since AD 2000 are mainly apparent in high-elevation fir, which may be a consequence of the observed trend towards warmer temperatures, particularly during winter. This synthesis effort should be useful to establish baselines for tree-ring data in Nepal and provide a broader context to evaluate the sensitivity or behavior of this proxy in the central Himalayas.


The Holocene ◽  
2021 ◽  
pp. 095968362110116
Author(s):  
Jeroen DM Schreel

Over the last few decades – at a range of northern sites – changes in tree-ring width and latewood density have not followed mean summertime temperature fluctuations. This discrepancy sharply contrasts an earlier correlation between those variables. As the origin of this inconsistency has not been fully deciphered, questions have emerged regarding the use of tree-ring width and latewood density as a proxy in dendrochronological climate reconstructions. I suggest that temperature is no longer the most limiting factor in certain boreal areas, which might explain the observed divergence.


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