| 20 Apr 2026
Precipitation variability inferred from tree rings in the eastern Tianshan Mountains over the past two centuries
Abstract. Tree rings serve as precise archives of the environmental conditions that influence tree growth. In this study, we collected tree-ring cores from Schrenk spruce (Picea schrenkiana) in the eastern Tianshan Mountains and developed a robust ring-width chronology. Growth-climate response analysis revealed that total precipitation from the previous July through the current June is the primary factor limiting radial growth in this species, a relationship that remained stable over the period 1961–2020. Based on this strong climatic signal, we reconstructed annual precipitation for the region from 1830 to 2020. The reconstruction explains 37.6 % of the variance in instrumental precipitation records, demonstrating its reliability as a proxy for past climate. The reconstructed series identified distinct dry periods (e.g., 1830–1839, 1863–1868, 1919–1921, 1944–1947, 1975–1979, and 1989–1992) and wet periods (e.g., 1844–1850, 1869–1882, 1886–1899, 1930–1942, 1966–1973, 1980–1988, 1996–2001, and 2004–2018). The validity of our reconstruction is further supported by its strong agreement with other precipitation and drought reconstructions from nearby regions. Moreover, comparison with the Climatic Research Unit (CRU) gridded dataset indicates that our reconstruction captures precipitation variability across a broad spatial domain. By extending the instrumental record, this long-term precipitation series significantly enhances our understanding of climatic variability and its spatiotemporal characteristics in the eastern Tianshan Mountains. Notably, the reconstruction reveals a general upward trend in annual precipitation since the 1990s, which may enhance growth and carbon sequestration potential of Schrenk spruce forests in the region.
This study presents a tree-ring based reconstruction of annual precipitation (previous July to current June) for the eastern Tianshan Mountains spanning 1830–2020. However, the explained variance of the reconstruction is only 37.6%, which falls below the generally accepted threshold of >40% reported in most dendroclimatological publications. Given the extensive body of dendroclimatological research already conducted in the Tianshan Mountains, including the eastern region, for example, Zhang et al. (2015) reconstructed precipitation variations for the Mulei region over the past 281 years, this work offers limited novelty in terms of both reconstruction length and temporal coverage. Furthermore, the discussion remains superficial and fails to generate new insights into climate change in the eastern Tianshan Mountains. Therefore, the manuscript is not suitable for publication in Climate of the Past in its current form.
Specific Comments
Table 2: Is "S" intended to denote the Sign Test (ST)? I question whether the authors fully understand what ST represents and how it is calculated. For the period 1961–1990, N = 30, yet the reported ST is 27+/11−; similarly, for 1991–2020, N = 30 but ST is reported as 30+/7−. These values are inconsistent with the sample sizes and require clarification.
Line 215–225: This section should characterize the temporal patterns of precipitation variability, rather than merely listing dry and wet years. A more systematic analysis of decadal to centennial trends, periodicities, or regime shifts is needed. Moreover, regarding the statement “although some discrepancies are evident”, what specific discrepancies are being referred to?
Line 28–30: It is inappropriate to state that "The validity of our reconstruction is further supported by its strong agreement with other precipitation and drought reconstructions from nearby regions." The validity of a reconstruction should be established primarily on the strength of the tree-ring width–precipitation relationship and the robust statistical characteristics of the regression model. Agreement with independent records can only demonstrate spatial coherence of hydroclimatic conditions to a limited extent. Please revise all related statements throughout the manuscript accordingly.
Line 101–104: The spatial distribution of the five sampling sites (longitude, latitude) and the 180 sampled trees is unclear. What is the distance between sites? What is the rationale for combining 161 samples from five distinct sites into a single tree-ring chronology? The sampling environment, including associated tree species, soil conditions, and inter-tree distances, should be described in detail to allow readers to assess sampling conditions and interpret the tree growth–climate relationship appropriately.
Fig. 1: The map scale is too large to clearly display the five sampling sites. Please rescale the map or provide an enlarged inset showing the sampling locations and meteorological station.
The geographic coordinates (longitude, latitude) and elevation of the Mulei meteorological station should be reported.
Line 122–126 and Table 1: The reported Rbar and EPS values appear to derive from a common period analysis rather than the full chronology length (1830–2020). Please specify the common period used. Generally, running Rbar and EPS statistics are more informative for evaluating chronology quality and should be provided.
Line 203: The text states RE = 0.18 and CE = 0.15, but these values do not match those in Table 2. Please clarify this discrepancy.
Table 2:
Line 217–219: Please provide references for the criteria used to define dry (extremely dry) and wet (extremely wet) years.
Fig. 8 and Line 315: What does "11-year loess smoothed trend" mean? Please clarify the smoothing parameters and methodology. Additionally, the "11-year loess smoothed trend" in this figure does not match that in Fig. 9a. Please clarify this difference.
Line 222–224: The results presented in Fig. 10 are not sufficiently convincing to support the claim that precipitation in the study area captures climatic variability across the broader eastern Tianshan region.
Line 312–328: The comparison with other records should explicitly address similarities and differences, rather than offering general and vague statements. A more critical and structured synthesis is required.
Line 219–220: The statement "A complete listing of these years is provided in Table 3" suggests that individual dry/wet years are tabulated. However, Table 3 presents dry and wet periods, not specific years. Please revise the text or the table to ensure consistency.
Fig. 5:
Line 151-154: Classic reference(s) for the split-sample calibration–verification procedure should be provided.