柴达木盆地东缘青海云杉树轮细胞结构变化特征及其对气候的指示

基于青海柴达木盆地东缘山地青海云杉生长上限的树轮样本,在获取树轮宽度数据的同时,获取了细胞特征指标,包括细胞个数和细胞大小,建立了树轮早材、晚材、整轮的细胞个数标准年表和细胞大小的最大值、最小值年表,并通过与附近茶卡气象站过去31年（1970—2000年）逐月降水量和温度的相关分析和响应函数分析,从细胞尺度探讨了青海云杉生长与外界气候要素的关系.结果表明：早材细胞个数与冬半年（上年10月至当年3月）温度之间呈正相关关系;晚材细胞个数除了与11月和12月最低温度呈显著正相关外,还与生长季中7月和8月平均温度呈显著相关关系;早、晚材细胞个数同时与7月的降水量呈显著负相关.早材细胞个数与5月的降水量呈正相关关系.对于早材最大细胞大小的年表来说,其变化与2月的降水量变化有很好的一致性,而晚材最小细胞的大小与8月降水量的变化同步.细胞个数和细胞大小不仅记录了树轮宽度所记录的温度变化信息,还额外记录了一定的降水信息,说明不同的树木生长指标能够记录不同的气候信息.利用同一地点同一树种不同类型的树轮指标,能够提取多种气候要素的变化信息,这对将来从同一样点的树轮资料中提取更丰富的气候信息以及发掘树轮气候学的潜力具有一定意义.     

升温对祁连山东部青海云杉径向生长的影响

在祁连山东部西营河流域不同海拔采集年轮样品,利用树木年代学方法建立高海拔(3000 m)、中海拔(2750 m)、低海拔(2500 m)青海云杉标准化年表,将年轮宽度指数与不同时段气温和降水分别进行相关分析,研究祁连山东部不同海拔青海云杉径向生长对气候变暖的响应。结果表明: 水热是祁连山东部青海云杉径向生长的主要限制因子,不同海拔树木的生长限制因子基本一致。在显著升温之前(1961—1986年),低、中、高海拔3个样点的青海云杉径向生长均与上一年7—8月和当年8月平均最高温呈显著负相关,与当年6月相对湿度呈显著正相关。显著升温之后(1986—2014年),高、中、低海拔树木生长与气温仍呈显著负相关,而与当年2月的相对湿度由升温前的不显著负相关转为显著正相关,与6月降水和相对湿度由升温前的显著正相关转为不显著的负相关。升温导致祁连山东部各海拔青海云杉树轮生长变慢,其中高海拔所受影响最大。气候变暖导致的干旱胁迫可能是青海云杉径向生长发生变化的主要原因。     

Growth and response patterns of Picea crassifolia and Pinus tabuliformis to climate factors in the Qilian Mountains,northwest China

Different tree species exhibit different phenological and physiological characteristics, leading to complexity in inter-species comparison of stem radial growth response to climate change. This study explored the climate-growth responses of Qinghai spruce (Picea crassifolia) and Chinese pine (Pinus tabulaeformis) in the Qilian Mountains, Northwest China. Meanwhile, Vaganov-Shashkin model (VS-oscilloscope) was used to simulate the relationships between radial growth rates and phenology. The results showed that 1) in their radial growth patterns, Qinghai spruce showed a significant increasing trend, while Chinese pine showed a decreasing trend, and Qinghai spruce has a longer growing season than Chinese pine. 2) For the radial growth-climate dynamic response, Qinghai spruce was influenced in an unstable manner by the mean temperature in the mid-growing season of the current year and the late growing season of the previous year and by the mean minimum temperature in the mid-growing season of the current year, while Chinese pine was influenced in a stable manner by the mean temperature and mean maximum temperature during the growing season of the current year. 3) The radial growth rates of the two conifer species were limited by temperature at the initiation and cessation of growth and by soil moisture at the peak of growth. But Chinese pine was more severely affected by soil moisture than Qinghai spruce in the middle of growth. Therefore, different management and restoration measures should be taken based on the differences in ecological responses and physical and physiological properties of the two conifer species to climate change in the subalpine forest ecosystems in the semiarid and arid regions of Northwest China.     

Application of Picea wilsonii roots to determine erosion rates in eastern Qilian Mountains, Northwest China

As a consequence of global change and human activities, processes of soil erosion are expected to increase in forested areas, resulting in exposed roots. Dendrogeomorphic research was conducted by analyzing exposed roots of Picea wilsonii subjected to continuous denudation along a main road in Tulugou National Forest Reserve, eastern Qilian Mountains, to reconstruct the local soil erosion dynamics. We determined the start of the exposure by examining the shifts in the ring-growth patterns from concentric to eccentric and by analyzing the detailed changes of wood anatomical features of exposed roots. We also find that the width of growth ring, the percentage of latewood and the average cell size of earlywood tracheids are all remarkable signs for soil lowering. According to the analysis of ANOVA (Fisher’s least significant difference method), the reduction of the cell size of earlywood tracheids is verified to be the key indicator for dating the first year of exposure and occurs prior to the other two indicators. Using 40 roots from 23 trees spread along the road, it has been found that erosion rates vary between 3.3 and 13.5 mm/year with an average value about 5.3 ± 2.1 mm/year. The intensity and occurrence of soil erosion may be influenced by the increase of human activities.     

阿尼玛卿山地不同海拔青海云杉(Picea crassifolia)树轮生长特性及其对气候的响应

利用位于同一坡面的青海云杉树芯样本,建立了4个海拔高度的树轮宽度指数年表。分析结果表明年表序列特征值大都因海拔而不同,各年表序列对气候因子的相关性在不同高度也表现出一定的差异:树木生长都与前一年10月份月均温显著正相关,与前一年8月份和当年5、6月份月均温显著负相关;与前一年9、10月份和当年5月份的降水量都呈显著正相关,但都随海拔升高呈波状变化。树轮宽度指数与不同时段的温度和温暖指数都呈负相关,表明5～9月是该地区青海云杉生长较为活跃的季节。响应函数分析结果表明该地区低海拔生长的青海云杉受温度和降水的影响都比高海拔生长的更显著,显然不同于以前研究的森林上下限树木的生长模式。4a表主成分中的第一主分量贡献率为81.071%,表明同一坡面影响树木生长的大环境因子是一致的。第一主分量与气候因子的相关分析同样显示出前一年生长季末和当年生长季初的水热组合是树木生长的主要限制因子,区域模拟也进一步证明了这一点。并认清了同一坡面青海云杉树轮记录的共性和差异,为今后树轮采样和研究提供一定的理论依据。     

Spatial distribution patterns and association of Picea crassifolia population in Dayekou Basin of Qilian Mountains,northwestern China

研究青海云杉(Picea crassifolia)种群不同发育阶段的空间分布格局及其关联性, 能揭示其种群的发展规律, 推断其潜在的生态学过程或影响机制, 进而为该种群的配置、种植和森林的经营与管理等提供指导。该研究基于祁连山大野口流域10.2 hm²青海云杉动态监测样地调查资料, 分析了青海云杉群落的物种组成和径级结构, 并采用点格局方法, 通过单变量成对相关函数和双变量成对相关函数对不同年龄阶段青海云杉种群的空间分布格局及其空间关联性进行分析。结果表明: (1)青海云杉种群的径级结构呈倒“J”型分布, 属增长型种群, 种群自然更新状况良好。(2)青海云杉种群4个径级的个体在小尺度上呈聚集分布, 但随着空间尺度的增大, 聚集强度逐渐减弱, 趋向随机分布; 较小径级的个体常呈聚集分布, 而随着径级增大, 也趋向于随机分布。(3)青海云杉大树个体在小尺度(<4 m)范围内与其他径级个体都呈负关联, 随着尺度的增加, 大树与幼树表现出正关联且关联性随尺度的增加而减弱, 而与小树、中树则表现为无关联或者微弱的负关联; 径级相近的个体空间关联性为正关联或无关联, 随着个体径级间差距增大, 空间关联性转变为无关联或负关联。研究表明, 祁连山大野口流域青海云杉种群的分布格局及其关联性随空间尺度和发育阶段而变化, 这是由种群自身的生物生态学特性、种内种间关系以及环境条件共同作用的结果。     

Individual and time-varying tree-ring growth to climate sensitivity of Pinus tabuliformis Carr. and Sabina przewalskii Kom. in the eastern Qilian Mountains, China

Individual tree-ring width chronologies and mean chronologies from Pinus tabuliformis Carr. (Chinese pine) and Sabina przewalskii Kom. (Qilian juniper) tree cores were collected and analyzed from two sites in the eastern Qilian Mountains of China. The chronologies were used to analyze individual and time-varying tree-ring growth to climate sensitivity with monthly mean air temperature and total precipitation data for the period 1958–2008. Climate–growth relationships were assessed with correlation functions and their stationarity and consistency over time were measured using moving correlation analysis. Individuals’ growth–climate correlations suggested increased percentages of individuals are correlated with certain variables (e.g., current June temperature at the P. tabuliformis site; previous June, December and current May temperature and May precipitation at the S. przewalskii site). These same climatic variables also correspond to the mean chronology correlations. A decreased percentage of individuals correlated with these climatic variables indicates a reduced sensitivity of the mean chronology. Moving correlation analysis indicated a significant change over time in the sensitivity of trees to climatic variability. Our results suggested: (1) that individual tree analysis might be a worthwhile tool to improve the quality and reliability of the climate signal from tree-ring series for dendroclimatology research; and (2) time-dependent fluctuations of climate growth relationships should be taken into account when assessing the quality and reliability of reconstructed climate signals.     

祁连山青海云杉叶片氮、磷含量随海拔变化特征

于2005年9月在祁连山北坡沿海拔梯度测定了青海云杉(Picea crassifolia)叶片氮、磷含量.结果表明,青海云杉叶氮、磷平均含量分别为9.75和0.97 mg·g-1.在种间水平上,青海云杉叶片氮、磷含量明显低于全球松科其它针叶树种;在种内水平上,随着海拔的增加,青海云杉叶片氮含量表现出降低的趋势,叶片磷含量变化趋势不明显.叶片氮含量与年均气温呈显著正相关关系(r=0.616**),与土壤水分呈显著负相关关系(r=-0.640**),与土壤有机质、全氮均呈显著负相关关系(r=-0.591**,r=-0.564**);叶片磷含量与年均温、土壤水分之间的关系不显著;叶片氮、磷之间的比率为10.2.表明温度和水分对青海云杉叶片氮、磷含量的影响主要是通过影响土壤生物化学过程(如养分有效性、根系对养分的吸收等)来实现的,青海云杉生长更多的受到氮素限制.     

Changes in the radial growth of Picea crassifolia and its driving factors in the mid-western Qilian Mountains,Northwest China since 1851 C.E

Examining the growth of trees in response to environmental factors is essential for evaluating the stability of forest ecosystems. In this study, using tree ring data obtained from 18 sites and climate diagnostic methods. we investigated relationships between the radial growth of Picea crassifolia in the mid-western Qilian Mountains and local climate/sea surface temperatures (SSTs) since 1851 C.E. The results revealed that the radial growth of P. crassifolia showed significant upward trends during three time periods (1884–1906, 1929–1946, and 1964–1983) and significant downward trends in a further three periods (1907–1928, 1947–1963, and 1984–1995). Variations in the growth of P. crassifolia showed a significant negative correlation with temperature in June and a positive correlation with precipitation from July in the previous year to June in the current year as a response to climate change. We also found that large-scale anomalies could influence the radial growth of P. crassifolia, which was reflected in results showing that extremely high radial growth is related to El Niño patterns in the central-eastern equatorial Pacific, whereas extremely low growth is related to anomalously warmer SSTs in the southern Indian Ocean. Notably, we found that the extremely low growth of P. crassifolia in response to SST was more stable than that of extremely high growth. Furthermore, on the basis of qualitative methodology, we established that years characterized by extremely high/low growth were largely/little influenced by the time window and threshold values that were selected when determining the positive/negative pointer years. Our results confirm the validity of using the relationships between extremely low growth and SSTs to predict forest dynamics.     

柴达木盆地荒漠植物功能性状及其对环境因子的响应

植物功能性状是植物适应环境的外在表达,反映了植物在不同环境中的生存策略,探究干旱区荒漠植物功能性状及其与环境之间的关系,有助于理解植物适应极端干旱环境的生态对策,为保护荒漠地区生态系统提供理论依据。以柴达木盆地为研究区,选取8个植物功能性状指标,包含4种植物生活型,10种荒漠植物,探究荒漠植物功能性状的基本特征及其对环境因子的响应。研究表明：柴达木盆地植物叶片碳含量(LCC)、叶片氮含量(LNC)、叶片磷含量(LPC)、叶片C∶N、叶片N∶P、叶片稳定碳同位素(Leafδ¹³C)、叶片干物质含量(LDMC)和植株高度(Height)的变化范围分别为272.07—466.00mg/g、12.40—44.50mg/g、0.51—2.07mg/g、8.62—29.74、11.37—39.29、-27.38‰—-14.80‰、100—480mg/g、3.00—264.22cm。不同生活型间LNC、LPC、叶片N∶P和LDMC差异不显著,LCC、叶片C∶N、叶片δ¹³C和植株高度存在显著差异。LNC、LPC和叶片N∶P与全球、中国和青藏高原相比不存在显...     

Responses to climate change in radial growth of Picea schrenkiana along elevations of the eastern Tianshan Mountains,northwest China

Tree growth is largely driven by climate conditions in arid and alpine areas. A strong change in climate from warm-dry to warm-wet has already been observed in northwest China. However, little is known about the impacts of regional climate variability on the radial growth of trees along elevations of the eastern Tianshan Mountains. Consequently, we developed three tree-ring width chronologies of Schrenk spruce (Picea schrenkiana Fisch. et Mey.) ranging in elevation from 2159 to 2552 m above sea level (a.s.l.), which play an important role in the forestry ecosystem, agriculture, and local economy of Central Asia. In our study, the correlation analyses of growth-drought using the monthly standardized precipitation-evapotranspiration index (SPEI) at different temporal scales demonstrated that drought in growing season was the main factor limiting tree growth, regardless of elevation. The relationships between radial growth of Schrenk spruce and main climate factors were relatively stable by moving correlation function, and the trend of STD chronologies and basal area increment (BAI) also showed a synchronous decline across the three elevations in recent decades. And meanwhile, slight differences in responses to climate change in radial growth along elevations were examined. The drought stress increased as elevations decreased. Radial growth at the higher elevation depended on moisture availability due to high temperature, as indicated by the significant negative correlation with mean temperature in the late growing season of the previous year (August-September, p < 0.001). However, radial growth at the lower elevation were restricted by drought stress due to less precipitation and higher temperatures, as demonstrated by the significant negative correlation with mean temperature but positive with total precipitation in the early growing season of the current year (April-May, p < 0.05). In addition, the decline of radial growth (BAI) at the higher elevation (3.710 cm² yr⁻¹/decade, p < 0.001) was faster than that of the middle elevation (2.344 cm² yr⁻¹/decade, p < 0.001) and the lower elevation (3.005 cm² yr⁻¹/decade, p < 0.001) since 2000, indicating that the trees at higher elevation of a relatively humid environment were more susceptible to the effects of climate change due to their poor adaptability to water deficit. Therefore, the forest ecosystems would be suppressed as a result of increasing drought stress in the future, especially in the high-elevation forests of arid and semi-arid areas.