Differential response of radial growth and δ^(13)C in Qinghai spruce(Picea crassifolia) to climate change on the southern and northern slopes of the Qilian Mountains in Northwest China

Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic factors.Tree-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern.Tree-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing season.Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did.The response between tree rings and climate in mountains gradually weakened as climate warmed.Changes in radial growth and stable carbon isotope fractionation of P.crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.

Finer topographic data improves distribution modeling of Picea crassifolia in the northern Qilian Mountains

The Qilian Mountains, a national key ecological function zone in Western China, play a pivotal role in ecosystem services. However, the distribution of its dominant tree species, Picea crassifolia (Qinghai spruce), has decreased dramatically in the past decades due to climate change and human activity, which may have influenced its ecological functions. To restore its ecological functions, reasonable reforestation is the key measure. Many previous efforts have predicted the potential distribution of Picea crassifolia, which provides guidance on regional reforestation policy. However, all of them were performed at low spatial resolution, thus ignoring the natural characteristics of the patchy distribution of Picea crassifolia. Here, we modeled the distribution of Picea crassifolia with species distribution models at high spatial resolutions. For many models, the area under the receiver operating characteristic curve (AUC) is larger than 0.9, suggesting their excellent precision. The AUC of models at 30 m is higher than that of models at 90 m, and the current potential distribution of Picea crassifolia is more closely aligned with its actual distribution at 30 m, demonstrating that finer data resolution improves model performance. Besides, for models at 90 m resolution, annual precipitation (Bio12) played the paramount influence on the distribution of Picea crassifolia, while the aspect became the most important one at 30 m, indicating the crucial role of finer topographic data in modeling species with patchy distribution. The current distribution of Picea crassifolia was concentrated in the northern and central parts of the study area, and this pattern will be maintained under future scenarios, although some habitat loss in the central parts and gain in the eastern regions is expected owing to increasing temperatures and precipitation. Our findings can guide protective and restoration strategies for the Qilian Mountains, which would benefit regional ecological balance.

Spatial and temporal patterns of the sensitivity of radial growth response by Picea schrenkiana to regional climate change in the Tianshan Mountains

Climate change significantly impacts forest ecosystems in arid and semi-arid regions.However,spatiotemporal patterns of climate-sensitive changes in individual tree growth under increased climate warming and precipitation in north-west China is unclear.The dendrochronological method was used to study climate response sensitivity of radial growth of Picea schrenkiana from 158 trees at six sites during 1990-2020.The results show that climate warming and increased precipitation significantly promoted the growth of trees.The response to temperature first increased,then decreased.However,the response to increased precipitation and the self-calibrating Palmer Drought Severity Index(scPDSI)increased significantly.In most areas of the Tianshan Mountains,the proportion of trees under increased precipitation and scPDSI positive response was relatively high.Over time,small-diameter trees were strongly affected by drought stress.It is predicted that under continuous warming and increased precipitation,trees in most areas of the Tianshan Mountains,especially those with small diameters,will be more affected by precipitation.

Spatial patterns of Picea crassifolia driven by environmental heterogeneity and intraspecifi c interactions

Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and species interactions in forest systems.In this study,spatial point pattern analysis investigated the combined eff ects of intraspecifi c interactions and environmental heterogeneity on the spatial structure and internal maintenance mechanisms of Picea crassifolia in the Qilian Mountain National Nature Reserve,China.Data were obtained from a 10.2-ha dynamic monitoring plot(DMP)and sixteen 0.04-ha elevation gradient plots(EGPs).Under complete spatial randomness,both mature trees and saplings in the DMP demonstratedlarge-scale aggregation with negative correlations.In EGPs,saplings were clustered in small mesoscales,mature trees were randomly distributed,and the interactions of saplingstrees at all elevations were not correlated.By eliminating the interference of environmental heterogeneity through the inhomogeneous Poisson process,saplings in the DMP and EGPs were clustered in small scales and trees randomly distributed.Intraspecifi c associations were negatively correlated,in the DMP and at low elevations,and no correlations in high elevations of EGPs.In the vertical scale,saplings showed a small-scale aggregation pattern with increase in elevation,and the aggregation degree fi rst decreased and then increased.The interactions of saplings-trees and saplings–saplings showed inhibitions at small scales,with the degree of inhibition gradually decreasing.Spatial patterns and associations of adults–adults did not change signifi-cantly.The results revealed that intraspecifi c interactions and environmental heterogeneity regulated the spatial patterns of P.crassifolia at small and large scales,respectively.Environmental heterogeneity might be the most decisive factor aff ecting the spatial patterns of saplings,while trees were more aff ected by intraspecifi c interactions.Moreover,competition between trees in this area could be more common than facilitation for the growth and development of individuals.

Divergent responses of Picea crassifolia Kom.in different forest patches to climate change in the northeastern Tibetan Plateau

Global climate changes have significantly affected tree growth and forest structures and functions in some arid and semi-arid regions,which are becoming warmer and wetter.Due to natural factors such as climate and terrain,some tree species may form different forest patches at the edges of their distribution areas.However,how forest patches of various sizes respond to climate change is unclear.In this study,we collected 203 tree cores from six different sizes of forest patches at the edge of the distribution area of Picea crassifolia Kom.in the northeast Tibetan Plateau.And we used the dendrochronology method to study the response of tree growth and resilience in different forest patches to climate change from 1961 to 2020.We simultaneously measured the contents of nonstructural carbohydrates(NSC),total nitrogen and total phosphorus of tree needles.Our results showed that the growth of trees in small-and medium-size forest patches(0.8–18.6 ha)has increased significantly.The early growing season(May–July)minimum temperature was the most important climate factor driving the growth of small-and medium-sized patch trees.The early growing season maximum temperature was the most important climate factor that inhibited the growth of trees in the largest patches(362.8 ha).The growth of individual trees in medium forest patches was better and the correlation with annual minimum temperature,maximum temperature,precipitation,actual evapotranspiration,and palmer drought severity index was stronger.The higher NSC content,stronger photosynthesis,and higher nitrogen utilization efficiency in leaves might be one of the reasons for the better growth of trees in moderate forest patches.In extreme drought years,as the forest patch area increased,the overall trend of tree growth resistance showed a unimodal pattern,with the highest at a forest patch area of 7.1 ha,while the overall trend of tree growth recovery was opposite.Therefore,we should strengthen the management of trees in large forest patches to cope with climate change.

基于红皮云杉(Picea koraiensis)重建大兴安岭南麓历史径流量

基于红皮云杉(Picea koraiensis)年轮宽度标准化年表重建了大兴安岭南麓贡格尔河流域1845—2016年历史径流量序列。结果表明:(1)贡格尔河流域在过去172 a共经历1853—1855年、2000—2010年2个枯水期和1869—1873年、1911—1918年、1952—1958年3个丰水期,丰水年及枯水年占比分别为17.4%和10.5%。(2)重建序列存在显著的3 a、7~12 a、15~22 a及30 a周期,研究区水文变化受全球大尺度气候环流活动的影响。丰、枯水期与该地区历史典籍记载的自然灾害高度重合,与附近其他重建结果相关性显著,重建方程稳定可靠。研究结果丰富了大兴安岭地区树木年轮数据库,为区域长历史时期水文变化的研究提供参考。

青海云杉(Picea crassifolia)种群格局的分形特征及其影响因素

应用计盒维数、信息维数和关联维数对祁连山主要森林类型青海云杉（Picea crassifolia）种群空间格局进行的研究表明：青海云杉种群格局计盒维数在0.992～1.938之间,平均值为1.716,信息维数在0.996～1.860之间,平均值为1.632,关联维数在1.418～1.759之间,平均值为1.568。计盒维数与样地海拔和土壤水分含量呈显著的负相关,与样地坡向呈显著的正相关,信息维数与样地海拔呈显著负相关而与坡向呈显著的正相关,关联维数与样地坡度呈显著的负相关,主成分分析表明,海拔和土壤含水量是影响青海云杉种群格局分形维数第一主成分,坡向是第二主成分,坡度是第三主成分,这3个主成分累计解释率为87.6%。

Formation, distribution, and nature of Picea mongolica in China

Picea mongolica is an endemic and endangered species in China. Ecosystem made of Picea mongolica is a special sandy forest ecosystem in China. It is found at ecotone between forest and steppe, or agricultural district and pastoral area. Based on investigation, this paper discussed the formation and distribution of Picea mongolica and studied its nature according to ecotone theory. It is clarified that Picea mongolica belongs to Picea meyeri series. That is to say, it became a local race through long-term adaptation to the local climate, then formed allopatric semi-species, and finally turned into a taxonomical species. Picea mongolica forest is a super zonal climax community developing in ecotone between forest zone and steppe zone.

A Dendroclimatic Study of Relic Picea meyeri in Inner Mongolian Steppe

Dendroclimatic methods were used to investigate the fundamental relationships between the temperature variables and the growth of climatically relic Picea meyeri Rehd. et Wils. on sandy land of Inner Mongolian grasslands in the Xilin River Basin. The annual mean temperature and accumulated temperature (above 5 ℃, 10 ℃) respectively showed no significant correlation with the spruce growth relative to summer mean temperature, which displayed strong coherence with tree growth ( P <0.01). The mean temperature in May showed significantly negative correlation with spruce growth ( P <0.05). Furthermore, it was revealed that the negative influence of May temperature was due to monthly mean maximum temperature ( T max ) ( P <0.01) other than monthly mean minimum temperature ( T min ) values ( P <0.1), which indicated that the use of T min and T max separately can allow much more insights on the temperate influence. In addition, extreme maximum temperature in May and June might impose the most detrimental influence on tree growth in semi_arid Inner Mongolian grassland. The analysis of the recorded meteorological data demonstrated that the increases in temperature were synchronous with slight decreases in precipitation in the growing season, which suggested that P. meyeri may reduce growth due to temperature_induced drought. On the other hand, the analysis for decadal periods explored that trees appeared to reduce the sensitivity to the warming, and consequently increased sensitivity to rainfall. This may serve as a baseline for more accurate predictions of the potential impacts of altered climate regimes on tree growth.

Study on tracheid variation of Picea koraiensis (nakai) in natural stand and plantation

Tracheid characteristics ofPicea koraiensis from natural stand in Liangshui area and plantation in Mao'ershan area were studied. The results of variance analysis showed that the tracheid length, diameter, and thickness of tracheid wall were significant differences between the growth rings. All those characteristics tend to increase from heart-center to bark. In natural stand, it has positive correlation between the characteristics. In plantation, the tracheid length has positive correlation with the trachied diameter, while both the trachied length and the trachied diameter has negative correlation with the thickness of trachied wall. The tracheid length and diameter have no significant difference in growth between natural stand and plantations. The thickness of tracheid wall from the plantation is a little thicker than that from the natural stand before 15 years.

Photosynthetic acclimation to long-term high temperature and soil drought stress in two spruce species (Picea crassifolia and P. wilsonii) used for afforestation

Picea crassifolia and P.wilsonii,commonly used for afforestation in northern China,are increasingly likely to be subjected to high temperatures and soil drought stress as a result of global warming.However,little is known about the effects of these stresses on foliar photosynthesis in the two species.To investigate how photosynthetic characteristics and sensitivity respond to prolonged high temperatures and soil drought,foliar gas exchange and other closely related parameters were recorded from four-year-old seedlings of both species.Seedlings were grown under two temperature treatments(25/15 and 35/25 °C) and four soil water regimes [80,60,40 and 20% of maximum field capacity(FC)] for 4 months.Although all treatments significantly reduced photosynthetic rates(Pn) of both species,P.crassifolia exhibited greater photosynthetic acclimation than P.wilsonii.Differences in photosynthetic acclimation were mainly related to variations in stomatal conductance(Cond) and the maximum quantum yield of PSII(Fv/Fm) between treatments.Indeed,higher Cond and Fv/Fmin all treatments were shown for P.crassifolia than for P.wilsonii.Moreover,photosynthesis in P.crassifolia exhibited inherently lower temperature sensitivities(broader span for the temperature response curves; lower b) and higher thermostability(invariable b between treatments).Further,severe drought stress(20% FC) limited the survival of P.wilsonii.Our results indicate that P.wilsonii is more susceptible to high temperatures and soil drought stress.Planting P.crassifolia would be more expected to survive these conditions and hence be of greater benefit to forest stability if predicted increases in drought and temperature in northern China occur.

Effects of Climatic Factors on Tree-ring Maximum Latewood Density of Picea schrenkiana in Xinjiang, China

Based on two tree-ring maximum latewood density （MXD） chronologies of Picea schrenkiana from the Manas River Basin, Xinjiang, the response characteristics of MXD to climate variation was discussed. Correlation analysis between MXD chronologies and instrumental records from Shihezi meteorological station showed that each chronology was significantly and positively correlated with the maximum monthly average temperature in July-August, and especially, the regional chronology （RC） was the most highly correlated variable （r=0.54, P〈0.001）. Afterwards, the maximum average temperature in July-August was reconstructed using RC. Comparison among reconstructed temperature, observed values, and the drought index （Is） confirmed that precipitation would affect MXD when the absolute value of Is is greater than 1.5σ （｜Is｜ 〉 2.5 during 1953-2008） or near to 1.5a over a 2-3 year period. The response characteristics are related to the semiarid climate of the study area. In dry years, lack of precipitation would limit the thickening of latewood cell walls and, as a result, impact MXD. Therefore, compared with relatively humid regions, the response of tree-ring MXD to air temperature similarly would be influenced by extreme moisture conditions in semiarid areas, and MXD, as a temperature proxy, should be used prudently on a limited scale.

Establishment and Optimization of ISSR-PCR Reaction System for Picea crassifolia kom.

[Objective] The experiment aimed to determine the optimum ISSR-PCR reaction system of Picea crassifolia kom. [Method] Picea crassifolia kom. was used as material to select and optimize influencing factors of ISSR-PCR such as Mg2+, dNTPs, Taq DNA polymerase, template DNA, primers, annealing temperature. [Result] The optimum ISSR-PCR reaction system in 20 μl reaction system was consisted of 1 μl 10×buffer, 1.5 mmol/L Mg2+, 0.2 mmol/L dNTPs, 1.0 U Taq DNA polymerase, 40 ng template DNA, 0.6 μmol/L primers. According to gradient test of annealing temperature in optimum ISSR-PCR reaction system of Picea crassifolia kom, it was found that the optimum annealing temperature of UBC 818 was 54.2 ℃ and the annealing temperature was different for different primers.[Conclusion]The construction of ISSR-PCR reaction system provided technical basis for classification of germplasm resources, construction of genetic map, gene mapping of Picea crassifolia kom. through using ISSR technology.

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。

祁连山青海云杉(Picea crassifolia)夜间树干液流特征及影响因素

利用SF-300树干液流仪对祁连山中段青海云杉(Picea crassifolia)2011年生长季树干液流进行监测,研究了在典型天气条件下青海云杉的夜间树干液流特征,以及气象因子和树形特征对其夜间液流变化的影响.结果表明:典型晴天、阴天,夜间树干液流速率分别在(2.78±0.64)^(5.02±1.06)g·cm-2·h-1、(2.31±0.62)^(3.94±1.22)g·cm-2·h-1之间波动,其平均值分别为(3.55±0.28)g·cm-2·h-1、(3.06±0.24)g·cm-2·h-1;夜间树干液流量分别占当日总液流量的(34.51±6.20)%、(46.06±11.20)%.夜间树干液流速率与饱和水汽压差、气温呈显著相关关系,与风速相关性不显著;夜间树干液流与胸径、树高、边材面积、胸径平方与树高之积呈显著线性相关,与冠幅相关性不显著.青海云杉夜间树干液流的变化是其生理特征与环境因素综合作用的结果,夜间树干液流可能用于夜间蒸腾和植物体内部的水分补充.

天山北坡不同环境条件下雪岭云杉(Picea schrenkiana)林限土壤属性

为了研究干旱区天山北坡中山带长达1000余公里的单建群种山地针叶林的空间分布原因,选择精河、玛纳斯、阜康和巴里坤中山带作为四种不同的环境条件,通过对不同环境条件雪岭云杉(Picea schrenkiana)上、下限土壤的采样与分析,探讨土壤因素对天山北坡中山带雪岭云杉分布的控制作用。雪岭云杉在天山北坡的连续分布主要是水热组合条件和土壤因素相互作用的结果,上、下限土壤属性变化与环境条件变化间存在着紧密的联系,表现为降雨量丰富的玛纳斯林区土壤肥力较高,但CaCO3含量较低,而降雨量较小的巴里坤和精河林区土壤肥力较差,但CaCO3含量较高。虽然长达1000余公里的雪岭云杉中山带环境条件差异较大,但其土壤属性变化均在雪岭云杉发育所需土壤条件的允许范围之内,这主要是受土壤成土母质、不同海拔高度的降雨量、地形、局地环流等因素的共同影响。

祁连山青海云杉(Picea crassifolia)林土壤有机碳与化学性质的相互关系

通过对祁连山大野口流域的青海云杉林大样地进行土壤剖面取样,分析了样地土壤有机碳与p H值、养分和阳离子交换量等基本化学性质的变化规律及其相互关系.结果表明：随土层深度不断增加,土壤有机碳含量逐渐减小,在20~30 cm以下趋于稳定（P〉0.05）;土壤p H值不断增大,仅在0~10 cm与10~20 cm差异显著（P〈0.05）;土壤全氮、速效氮、全磷和阳离子交换量不断减小,全氮含量在30~40 cm以下趋于稳定（P〉0.05）,速效氮含量变化剧烈（P〈0.05）,全磷含量差异性不显著（P〉0.05）,阳离子交换量与有机碳含量变化规律相同;土壤速效磷、全钾和速效钾含量没有明显的变化规律,速效磷和全钾含量差异性不显著（P〉0.05）,速效钾含量仅在0~10 cm与10~20 cm差异显著（P〈0.05）.土壤有机碳与全氮、速效氮、全磷、速效磷、速效钾和阳离子交换量之间呈极显著和显著正相关,与土壤p H值和全钾含量之间呈极显著和显著负相关.土壤有机碳与其他基本化学性质的回归方程具有较高精度（R2=0.793）,影响土壤有机碳含量的主要化学因子依次为土壤阳离子交换量、速效钾和全磷含量.

利用半球图像反演祁连山区青海云杉(Picea crassifolia)林盖度

青海云杉是祁连山森林生态系统的主要建群种,具有重要的生态水文功能。冠层盖度是评估生态环境的一个重要参数,但目前缺乏有效评估手段。半球摄影技术在估算林冠盖度方面已显示出潜在优势,但它受到环境条件例如天气的影响仍然没有报道。在祁连山排露沟流域利用半球摄影技术反演冠层盖度,界定不同天气条件对阈值的影响,评估与传统方法估算林冠盖度的差别,结果表明:分类阈值受天气状况的影响较大,阴天的最佳阈值为118,晴天的最佳阈值为149;另外传统观测与半球图像法获得的林冠盖度有一定的差异,其中最大差值17.88%,最小差值5.34%。该项研究对青海云杉林盖度估算提供新的方法,为生态水文过程模型提供有价值的输入参数。

天山云杉(Picea schrekiana Fisch et Mey)凋落物的自毒效应

天山云杉(Picea schrekiana Fisch et Mey.)是亚洲中部山地的特有物种,在中国仅见于新疆,其主要分布在天山南北坡和昆仑山西部北坡,对天山的水源涵养、水土保持和林业生产具有不可或缺的重要作用。然而天山云杉林的天然更新不良和障碍成为困惑新疆林业工作者的一大难题。从植物间的化感与自毒作用研究着手,分析了天山云杉凋落物水提液的乙醚、乙酸乙酯、正丁醇萃取物对自身种子萌发和幼苗生长的影响。以种子发芽率、发芽势和发芽指数作为种子萌发参数,以胚根、胚芽长度和实生苗干湿重的变化作为幼苗生长参数。研究结果表明:种子萌发试验中乙醚萃取物具有最强的抑制效应(IC50=5.00mg/mL),而正丁醇萃取物的抑制效应最弱(IC50>10.00 mg/mL);幼苗生长试验中,1.25 mg/mL的乙醚萃取物对幼苗生长具有显著的抑制作用(P<0.05),1.25 mg/mL的正丁醇萃取物能够促进其幼苗生长,大于2.5 mg/mL的正丁醇萃取物对幼苗生长都具有显著的抑制效应(P<0.05)。采用GC-MS-MS技术分析三种有机萃取物的化学组成,共鉴定并定量分析出了包括酚酸、长链脂肪酸、单宁酸和吲哚类物质在内的17种化合物。乙醚萃取物中存在的2-keto-4a-methyl-8-methoxy-2,3,4,4 a,5,6,11,12-ocahydrochrysene为一新的化感物质,证明了天山云杉凋落物中存在的化感与自毒物质是导致其种群天然更新障碍的最主要原因,同时揭示了自毒作用发生的化学物质基础。

青海云杉(Picea crassifolia)边材心材边界的确定及树干传输水分的空间格局

利用染色法和SF-300树干液流仪分别区分了青海云杉树木的边材与心材的边界,并用树干液流法研究了青海云杉树干传输水分的空间格局.结果表明:染色法与树干液流法均能有效区分青海云杉树木的边材与心材,但染色法更方便、快捷;利用染色法测定的青海云杉树木边材宽度与其胸径大小呈指数函数关系.青海云杉树干液流速率从边材外缘向里逐渐增大,达到最大值后又逐渐减小,其水分传输格局基本呈对称分布的.