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.

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。

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%。

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.

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。

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.

内蒙古贺兰山地区青海云杉(Picea crassifolia)外生菌根真菌多样性研究

青海云杉是中国的特有植物,生于海拔1750~3100m的山地阴坡和半阴坡及潮湿的地带。文章以内蒙古贺兰山自然保护区的青海云杉为研究对象,运用454GS测序技术对青海云杉外生菌根真菌进行了多样性分析。结果发现:青海云杉外生菌根真菌非常丰富,隶属于2个门4个纲14个目20个科25个属,有效OTU序列共143条。

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(P_n) 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(F_v/F_m) between treatments.Indeed,higher Cond and F_v/F_m in 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.

The type, position and age effect on the cutting reproduction of Picea crassifolia and its rooting mechanism in the Qilian Mountains

Picea crassifolia Kom, a perennial arbor species is recognized as one of the most adaptable plants found to date in Qilian Mountains. To explore the cutting reproduction technology of P. crassifolia and reveal its rooting mechanism, cuttings of P. crassifolia with different cutting types(softwood, hardwood and root), positions(top, upper, middle and bottom) and ages(7, 10, 15, 20,25 year-old) were cultivated in a field experiment. Oneyear old softwood and hardwood cuttings were collected from 7-, 10-, 15-, 20-, and 25 year-old healthy ortets to analyze the changes from endogenous hormones and organic nutrients. Results indicate that the softwood cuttings(0.5–1.0 cm in diameter) from upper branches of15 year-old ortets shows better growth performance by improving rooting indexes, including a significant increase in rooting rate and a decrease in basal rot rate. Concomitantly, increasing rooting quantity and root length also increased. It is noteworthy that the high rooting rate of P.crassifolia cuttings due to its ability to accumulate high concentrations of indole-3-acetic acid(IAA) and total carbon(TC) rather than abscisic acid(ABA) and total nitrogen(TN). The rooting rate was mainly regulated by the IAA/ABA and TC/TN ratio. In summary, our results suggest that the softwood cuttings(0.5–1.0 cm in diameter)from upper branches of 15 year-old P. crassifolia can be considered as an effective strategy to improve cutting rooting rate, and the IAA/ABA and TC/TN ratio was one of the main factors limiting the cutting rooting rate of P.crassifolia.

Spatial patterns in natural Picea crassifolia forests of northwestern China,as basis for close-to-nature forestry

Close-to-nature forest management has been proposed as an effective method for improving the quality of plantation forests. Knowledge of spatial distribution patterns, structure, and succession trajectories in natural forests can provide guidelines for the establishment of close-to-nature forest plantations. Such knowledge is lacking in natural spruce(Picea crassifolia) forests in the Qilian Mountains of China, impeding the establishment of production forests. We conducted a case study in the Qilian Mountains to analyze the relationships between the naturally-formed forest patches and terrain factors, spatial heterogeneity of stand characteristics, and stand structure following harvesting disturbance. Our results suggested that spruce plantations will be effective on the N, NE, and NW slopes, at elevations between 2700 and 3300 m, and on slopes ranging from 15° to 45°. Further, planted forest patches should occupy 64% of the slope area on semi-shady slopes(NE, NW). Spatial patterns in the studied forest exhibited a strong scale-effect, and an area of 0.25 ha could be used as the most efficient plot scale for the management of spruce plantations. Partial logging is an effective method for the conversion of spruce planted forests into nearnatural forests, and the intensity of partial logging can be determined from the negative exponential function relationship between stand density and DBH. Our results provided critical information for the development of spruce plantations and conversion of existing plantations.

Response to climate changes in radial growth of Picea crassifolia in the Qilian mountains of northwestern China

In order to investigate the response to climate changes in radial growth of Picea crassifolia at the lower tree line in the middle Qilian mountains in northwestern China, relationships of standardized chronologies of annual ring, earlywood and latewood widths with mean monthly temperature and total monthly precipitation were analyzed by ways of correlation and pointer year analyses. The results show that annual ring, earlywood and latewood widths are significantly negatively correlated with mean monthly temperature in June and July. Annual ring and earlywood widths are significantly and positively correlated with total monthly precipitation in March, May and June and negatively correlated with total monthly precipitation in September. Latewood width is less sensitive to climate changes than the width of earlywood and insignificantly sensitive to precipitation. The results of pointer year analysis revealed that when summer temperatures are higher than the mean summer temperature synchronization and the summer precipitation lower than mean summer precipitation synchronization, narrow annual rings are formed. Wide annual rings are formed when summer temperatures are lower than the mean summer temperature synchronization and summer precipitation higher than mean summer precipitation synchronization. The results indicate that more precipitation in the spring and summer is helpful for radial growth while warmer summer restricts radial growth of P. crassifolia at the lower tree line in the middle Qilian mountains.

Spatiotemporal variability in tree ring's δ^(13)C of Picea crassifolia in the Qilian Mountains:climatic significance and responses to rising CO_2

The carbon isotopic composition (δ13C) of tree rings was used to assess changes in intrinsic water-use efficiency (Wi) to increasing atmospheric CO2 and climate change during the period of 1891-2003.Five Qinghai spruce (Picea crassifolia) stands were selected in the Qilian Mountains,growing along a precipitation gradient.All five δ13C were correlated to each other,but two sites (DDS and CLS),which are far from the main body of the mountains,show relative weak connections to other sites.Although trees at all sites had improved their Wi in response to increasing atmospheric CO2 concentration,spruce growing in the regions far away from the main body of the mountains were less sensitive to improved Wi than those of other sites.Based on the correlation between carbon isotope discrimination (Δ) and Palmer Drought Severity Index (PDSI),the drought history covering the period of 1891-2003 was reconstructed in the study region.The two most severe drought epochs of the late 1920s and the last decade were caused by reduced precipitation and climate warming,respectively.Our results will be useful in assessing any further spatial climate-related bioclimatic information.

祁连山排露沟流域青海云杉(Picea crassifolia)林土壤水分特征

土壤水分是植物生长的关键水分来源,对生态系统的演变具有重要作用。选取祁连山排露沟流域青海云杉(Picea crassifolia)林为研究对象,通过建立固定样地,进行了两个生长季的分层(0~10、10~20、20~30、30~40、40~50、50~60 cm)土壤含水量监测。结果表明:(1)在各海拔青海云杉林之间,土壤含水量差异很大,海拔3 300、3 100、2 900、2700、2 500 m处土壤水分含量依次降低。(2)青海云杉林土壤含水量随土壤剖面深度的增加呈降低趋势,土壤含水量变异系数随土壤深度增加有递减的趋势;0~10 cm土层土壤含水量的变异系数最高。相同土层的含水量变异系数海拔2 500 m处>2 700 m处>2 900 m处>3 100 m处>3 300 m处。(3)小流域空间尺度内,海拔、降水、温度和土壤特性等因素共同作用,影响着土壤含水量的差异,使土壤含水量的空间分布具有随海拔升高而增大的变化规律。

基于机载雷达数据的青海云杉(Picea crassifolia)林降雨截留空间模拟

以祁连山天老池流域青海云杉（Picea crassifolia）林为对象,以2013年降雨截留观测数据和机载雷达数据,结合GIS技术对青海云杉林进行流域尺度上的截留模拟。先以样方尺度上观测的数据建立截留量统计模型,然后利用机载雷达数据计算冠层激光穿透指数（LPI）,根据LPI与叶面积指数（LAI）的关系实现对青海云杉LAI的反演,最后利用青海云杉林区降雨量和LAI空间分布数据,在GIS的空间分析中,模拟研究区青海云杉林截留的空间分布。结果表明：2013年生长季研究区青海云杉林林冠截留量0～331.0mm,平均161.9mm,林冠截留率在0～67.97%,平均33.89%;整个生长季,流域青海云杉林冠截留量约5.26×10^5 m^3,占整个流域生长季总降雨量的7.38%。

利用混合线性模型对青海云杉无性系生长性状进行早期评价

通过对100个青海云杉无性系不同树龄(7、9、13、14 a)时期的生长性状进行遗传测定及选优,为甘肃省天水小陇山地区青海云杉的良种选育与推广应用提供基础。采用完全随机区组设计,营造5个区组2株小区建立100个青海云杉无性系对比试验林,对试验林7、9、13、14 a时期生长性状,如树高、新梢、胸径、冠幅进行调查,并通过数据整理分析及遗传参数估算,选择优良无性系。结果表明:青海云杉无性系7、9、13、14 a树高、新梢、胸径、冠幅均呈极显著差异(P<0.01)。通过各树龄的树高方差分析可以看出,树龄、区组、无性系、树龄×无性系互作效应、区组×无性系互作效应均有显著差异(P<0.05),树龄效应方差分量占比为77.5%,受树龄效应影响较大。不同树龄时无性系各性状表型变异系数为22.07%~60.37%,遗传变异系数为7.55%~29.78%,重复力为0.36~0.86。采用最佳线性无偏估计法计算无性系树高遗传值,从100个无性系中选出5个青海云杉无性系,其入选率为5%,树高遗传增益为15.65%。青海云杉无性系生长性状存在广泛遗传变异,无性系对树高的方差分量占比逐年提升,生长性状受很强的遗传因素控制。根据树高育种值筛选的5个优良无性系分别为:08青大039、08青大035、08青大012、08青大018、08青大007。

地被物对祁连山青海云杉林土壤呼吸的影响

土壤呼吸是陆地生态系统碳循环的重要组成部分,对环境变化响应的敏感性受地被物强烈影响,并显著影响生态系统的碳源/汇功能。应用Li-8100A土壤碳通量自动测量系统,对祁连山青海云杉林下土壤呼吸进行野外测定,研究环境因素和不同地被物(苔藓和凋落物)对土壤呼吸动态变化的影响。将去除苔藓和凋落物的样地与对照组进行对比,并收集0~<20 cm、20~<40 cm、40~60 cm土壤温度和土壤含水量、光合有效辐射、风速风向、相对湿度和大气温度等数据。在日尺度上,土壤温度和空气温度是影响该地区土壤呼吸日变化的主要驱动因子,但与土壤含水量的变化没有显著相关性。在季节尺度上,20~60 cm土壤温湿度的变化是土壤呼吸季节变化的主要影响因素。研究区日均CO_(2)排放量约为311.66~728.61 mg·m^(-2)·h^(-1),去除苔藓生长季土壤碳排放减少约12%,而去除凋落物土壤碳排放减少约32%。移除苔藓或者凋落物可以显著增加土壤呼吸的温度敏感性(Q_(10))。研究结果表明青海云杉林下的苔藓和凋落物对土壤呼吸有显著影响,在估算区域土壤碳排放时应区分考虑。

绿洲城市交通干道绿化树种重金属富集特征及风险评价

选取张掖市交通道路绿地(试验区)和润泉湖公园绿地(对照区)中6种常见绿化树种为研究对象,运用电感耦合等离子体法(ICP)测定了绿化树种根、皮、叶重金属(Cr、Cd、Pb、Cu、Zn)含量,分析了绿化树种不同组织之间的重金属含量、富集系数(BCF)、转运系数(TF)、Muller地累积指数(Igeo)和富集因子(EF),结果表明:(1)不同绿化树种的重金属含量表现为Zn>Cr>Cu>Pb>Cd,Cr、Cu含量表现为树皮>树根>树叶,Zn含量表现为树皮>树叶>树根,Cd含量表现为树根>树皮>树叶。(2)青海云杉树根对Cd、树皮对Cr、Zn,白蜡树皮对Cu具有较强的富集能力。榆叶梅树叶和树皮对Cr、樟子松树叶和树皮对Zn的转运能力最强,绿化树种树皮对重金属的转运能力强于树叶。(3)交通道路旁表层土壤Cd属偏中度污染,且Cr超过了建设用地土壤污染风险筛选值和管控值。(4)Zn主要来源于人类活动,Pb、Cu的来源受到一定交通活动的影响。青海云杉、白蜡、榆叶梅可作为张掖市道路土壤重金属污染防治的首选绿化树种。

祁连山大河口青海云杉胸径变化关系的研究

胸径是林业调查中最重要的指标之一,可表征森林资源的生长变化规律。以甘肃省张掖市民乐县第八次和第九次森林资源连续清查中青海云杉6个固定样地为研究对象,通过分析对前后两期每木检尺胸径数据间的相关关系,旨在揭示青海云杉胸径变化规律。回归分析结果表明:青海云杉后期胸径与前期胸径的最优拟合公式为二次模型(D_(后)=0.369+1.038 D_(前)-0.001D^(2)_(前),D_(后)为第九次连续清查的胸径,即后期胸径;D_(前)为第八次连续清查时的胸径,即前期胸径)。模型方程计算结果与2023年实际测量的胸径数据较为吻合。由此可见,二次模型能够较好地反映祁连山区青海云杉胸径的生长变化关系,将为今后青海云杉种群预测提供理论依据。