[Effects of warming on radial growth of Picea crassifolia in the eastern Qilian Mountains, China]. / 升温对祁连山东部青海云杉径向生长的影响.

Tree-rings of Picea crassifolia from high (3000 m), middle (2750 m) and low (2500 m) altitudes were collected from the Xiying River basin in the eastern Qilian Mountains, with the standard chronology being established using dendrochronological methods. Results of the correlation analysis between tree-ring width index and temperature and precipitation during different periods showed that radial growth of P. crassifolia at different altitudes responded differently to climate warming in the eastern Qilian Mountains. Water and heat availability were the main limiting factors for the radial growth of P. crassifolia in the eastern part of Qilian Mountains. The growth limiting factors at different altitudes were generally the same. Before the prominent warming (1961-1986), radial growth of P. crassifolia at the three sampling altitudes was significantly negatively correlated with mean maximum temperature in July-August of the previous year and August of the current year, and significantly positively correlated with the relative humidity in June of the current year. After the prominent warming period (1986-2014), tree growth at high, middle, and low altitudes remained significantly negatively correlated with air temperature, changed from non-significantly negative to significantly positive correlation with relative humidity in February of the current year, and changed from significantly positive to non-significantly negative correlation with precipitation and relative humidity in June. Warming caused a slowing growth of P. crassifolia tree-ring at all altitudes, with the highest altitude being the most sensitive. Drought stress caused by climate warming might be the main reason for the changes of radial growth of P. crassifolia.

[Stem radial growth of Picea crassifolia in response to climatic factors in the western Qilian Mountains, China]. / ç¥è¿žå±±è¥¿éƒ¨é’æµ·äº‘æ‰å¾„å‘ç”Ÿé•¿å¯¹æ°”å€™å› å­çš„å“åº”.

The radial growth of eight individuals of Picea crassifolia and environmental factors were monitored by Dendrometer and automatic meteorological station in the western Qilian Mountains. The Gompertz function fitted results showed that the radial growth of P. crassifolia started on April 19, April 17, and April 10 in 2018, 2019 and 2020, respectively, and that the radial growth started when daily mean temperature exceeded 5.5 ℃. The radial growth of P. crassifolia ended on August 17, August 21, and July 19 in the three years, respectively. The ending time of radial growth was related to precipitation at the end of growing season. The radial growth of P. crassifolia was strongly inhibited by drought, and it had the strongest correlation with daily mean temperature (negative correlation) and daily precipitation (positive correlation) in July. The correlation of radial growth with the daily precipitation in the early growing season (May) showed significant inter-annual variation.

[Research progress on cambial activity of trees and the influencing factors]. / æ ‘æœ¨å½¢æˆå±‚æ´»åŠ¨åŠå ¶å½±å“å› ç´ ç ”ç©¶è¿›å±•.

Tree growth is the main way of carbon sequestration in forest ecosystems, which is influenced by climatic and non-climatic factors. The long-term location monitoring of cambial phenology and wood formation dynamics (xylogenesis) is an important method to clarify the responses of radial growth to climate change. Here, we reviewed studies on cambial phenology and xylogenesis by microcoring method. Firstly, we reviewed the effects of climatic factors on cambial phenology. The onset and cessation of xylogenesis were determined by temperature in cold and humid conditions. Temperature and water availability collectively modulated the onset of xylogenesis under dry conditions, and the later determined the end of xylogenesis. The radial increment was regulated by rate and duration of cell production, with the maximum of growth rate occurring around the summer solstice. Short-term N addition did not affect wood formation dynamics. Secondly, we reviewed the roles of biological factors in regulating xylogenesis. The onset of xylogenesis differred among species, ages, and inter-specific competition. Seasonal dynamics of non-structural carbohydrates were coupled with wood formation. Finally, we reviewed the response mechanisms of xylogenesis to the interaction of climatic and biological factors. In conclusion, we put forward problems in current studies and prospected future development to provide reference for further scientific research.