Characteristics of Soil Seed Bank and Natural Regenerations in Pinus densata Natural Forest of Southeast Tibet

Pinusdensata is one of the main constructive species for coniferous forests in southeast Tibet. P. densata forests are important water conservation forests in the drainage basins of the middle and lower reaches of Yalu Tsangpo River, Nyang River and Parlung Zangbo River. In this study, with P. densata forest distributed in southeast Tibet as research object, the seed rain, soil seed bank, seed germination and natural regeneration of P. densata were monitored and ana- lyzed by field investigation, located monitoring and indoor experimental analysis. The results showed that the average intensity of the seed rain of P. densata was 249.30±78.42 seeds/m2, in which the intensity of full seeds was 168.09±56.36 seeds/m2, the intensity of seeds damaged by worms was 41.11±20.25 seeds/m2, and the intensity of empty seeds was 40.10±21.04 seeds/m2. The intensity of the seed rain exhibited a single-peak trend of increasing at first and decreasing then over time. The spatial distribution patterns in the whole seed falling process and at different seed falling time all exhibited clumping distribution, and within in certain range, with the distance from the seed tree increasing, the diffusion intensity of the seed rain was weakened, exhibiting approximately normal distribution. In average density of P. densata seeds in the soil seed bank of P. densata was 231 seeds/m2, in which 62.77% of seeds were distributed in the litter layer, and 37.23% of seeds were distributed in the soil layer, and about 8% of seeds were lost during the pro- cess from seed rain to soil seed bank. Field sowing observation showed that the accumulated germination rate curve of P. densata fitted with Logistics equation y= 91.404/（1＋e66194.449）. The height structure, basal diameter structure and age structure of seedlings and young trees of P. densata were all of reverse ＂J＂ type, indicating good natural regeneration of P. densata. This study would provide a science basis for protection and resource management of P. densata, and further enrich the eval- uation content of national ecological safety curtain of the Tibet plateau.

滇西北白马雪山高山松(Pinus densata)径向生长对气候因子的响应

滇西北是我国西南地区气候变化最为显著的地区之一,过去几十年来气候呈现快速变暖趋势。高山松(Pinus densata)是该地区主要的针叶树种,研究高山松径向生长对气候因子的响应,有助于深入认识该地区亚高山针叶林对气候变化的适应能力。在滇西北白马雪山1 hm^(2)永久性样地内采集了161棵高山松树木样芯(322个),运用传统树木年轮学原理及方法,建立高山松年轮宽度差值年表,分析年表与样地附近气象站1957—2020年气候因子的相关性。结果表明:1)高山松的径向生长与冬季及春季(前一年11月至当年4月)温度呈正相关关系,与当年5月份最高温度和平均温度呈负相关;2)高山松径向生长与当年4—6月降水量显著正相关,与5月相对湿度呈正相关,与5—8月标准化降水蒸散指数(SPEI6)呈正相关;3)滑动相关分析表明,白马雪山高山松径向生长-气候关系不稳定,冬季温度对高山松生长的限制作用在减弱,说明冬季低温限制在一定程度上解除;而夏秋季温度对高山松径向生长的相关性由弱的负相关转为近年来的显著正相关;对夏季相对湿度和标准化降水蒸散指数的敏感性降低。研究结果可为探讨气候变化下高山松自然林的生长动态提供参考。

Estimating aboveground biomass of Pinus densata-dominated forests using Landsat time series and permanent sample plot data

Southwest China is one of three major forest regions in China and plays an important role in carbon sequestration.Accurate estimations of changes in aboveground biomass are critical for understanding forest carbon cycling and promoting climate change mitigation.Southwest China is characterized by complex topographic features and forest canopy structures,complicating methods for mapping aboveground biomass and its dynamics.The integration of continuous Landsat images and national forest inventory data provides an alternative approach to develop a long-term monitoring program of forest aboveground biomass dynamics.This study explores the development of a methodological framework using historical national forest inventory plot data and Landsat TM timeseries images.This method was formulated by comparing two parametric methods:Linear Regression for Multiple Independent Variables(MLR),and Partial Least Square Regression(PLSR);and two nonparametric methods:Random Forest(RF)and Gradient Boost Regression Tree(GBRT)based on the state of forest aboveground biomass and change models.The methodological framework mapped Pinus densata aboveground biomass and its changes over time in Shangri-la,Yunnan,China.Landsat images and national forest inventory data were acquired for 1987,1992,1997,2002 and 2007.The results show that:(1)correlation and homogeneity texture measures were able to characterize forest canopy structures,aboveground biomass and its dynamics;(2)GBRT and RF predicted Pinus densata aboveground biomass and its changes better than PLSR and MLR;(3)GBRT was the most reliable approach in the estimation of aboveground biomass and its changes;and,(4)the aboveground biomass change models showed a promising improvement of prediction accuracy.This study indicates that the combination of GBRT state and change models developed using temporal Landsat and national forest inventory data provides the potential for developing a methodological framework for the long-term mapping and monitoring program of forest aboveground biomass and its changes in Southwest China.

Variations in electrical impedance and phase angle among seedlings of Pinus densata and parental species in Pinus tabuliformis habitat environment

Electrical impedance （El） and phase angle （PHI） parameters in AC impedance spectroscopy are important electrical parameters in the study of medical pathology. However, little is known about their application in variation and genetic relationship studies of forest trees. In order to test whether impedance parameters could be used in genetic relationship analysis among conifer species, E1 and PHI were measured in a seedling experiment test composed of Pinus tabuliformis, Pinus yunnanensis, and Pinus densata in a habitat of Pinus tabuliformis. The results showed that variations in both EI and PHI among species were sig- nificant in different electric frequencies, and the EI and PHI values measured in the two populations of P. densata were between the two parental species, P. yunnanensis and P. tabuliformis. These results show that these two impedance parameters could reflect the genetic relationship among pine species. This was the first time using the two AC impedance spectroscopy parameters to test the genetic relationship analysis between tree species, and would be a hopeful novelreference methodology for future studies in evolution and genetic variation of tree species.

Capacitance Characteristics of Pinus densata,Pinus tabuliformis,Pinus yunnanensis and the hybrids Pinus tabuliformis×Pinus Yunnanensis

We employed capacitance to evaluate the kinship and interspecific variation of homoploid hybrid conifer Pinus densata,P.tabuliformis,P.yunnanensis and artificial hybrids of P.tabuliformis(maternal parent)and P.yunnanensis(paternal parent)which were cultivated and selected in the common garden experiment.By measuring capacitance spectra under different voltage frequencies,we could differentiate different germplasms based on the electrical response.We aims to demonstrate that P.densata as the hybrid of P.tabuliformis and P.yunnanensis based on the capacitance values of the species,and to provide new evidence to the previously known biological evidence,as well as and the parental effect on the hybrids.Our results revealed that capacitance values between the species are significantly different in the spectra where P.yunnanensis positioned at the lowest and P.densata was much higher than all other species,indicating that P.densata had possessed a great capacity to store electrical energy.The capacitance spectra of P.densata and the artificial hybrid are not similar,which rejected our hypothesis.Both of the capacitance values of P.densata and the hybrids were closer to P.tabuliformis than to P.yunnanensis,which shows that the maternal influence was stronger than the paternal influence.Correlation analysis on the relationship between capacitance and fitnessrelated characteristics showed that capacitance is negatively correlated to mortality rate,and positively correlated with second-year survival rate.High capacitance values of P.densata and some of the hybrids reveal their superior adaptability to harsh environment in the Tibet Plateau.We concluded that capacitance as a new indicator for plant fitness and evolution evidence of homoploid hybrid conifers.

Interspecific Variation and Phylogenic Architecture of Pinus densata and the Hybrid of Pinus tabuliformis×Pinus Yunnanensis in the Pinus densata Habitat:an Electrical Impedance Spectra Perspective

We evaluated a novel and non-destructive method of the electrical impedance spectroscopy(EIS)to elucidate the genetic and evolutionary relationship of homoploid hybrid conifer of Pinus densata(P.d)and its parental species Pinus tabuliformis(P.t)and Pinus yunnanensis(P.y),as well as the artificial hybrids of the P.t and P.y.Field common garden tests of96 trees sampled from 760 seedlings and 480 EIS records of 1,440 needles assessed the interspecific variation of the P.d,P.t,P.y and the artificial hybrids.We found that(1)EIS at different frequencies diverged significantly among germplasms;P.y was the highest,P.t was the lowest,and their artificial hybrids were within the range of P.t and P.y;(2)maternal species effect of EIS magnitudes in the hybrids and P.d was stronger than the paternal species characteristics;(3)EIS of the artificial hybrid confirmed the mid-parent and partial maternal species characteristics;(4)unified exponential model of EIS for the interspecific and hybrids can be constructed as|Z|=Af^(-B);(5)cluster analysis for species and hybrid combinations in total corroborated with the previous hybrid model of Pinus densata.Our non-destructive EIS method complemented the previous finding that Pinus densata was originated from P.t and P.y.We conclude that the impedance would be a viable indicator to investigate the interspecific genetic variations of conifers.

香格里拉市高山松林碳密度与环境因子的关系研究

以香格里拉市高山松林为研究对象,依据前期构建的高山松单木碳储量模型,结合森林资源二类调查数据推算高山松林的碳密度,利用除趋势对应分析方法探讨高山松林碳密度与各环境因子之间的关系。结果表明,在林分因素中,平均树高对高山松林碳密度的影响最大;在地形因素中,坡度对高山松林碳密度的影响最大;在温度因素中,最热月均温和最冷月均温差对高山松林的碳密度影响最大;在降水因素中,最干季降水和最冷季降水对高山松林碳密度的影响最大。环境因子的综合作用对高山松林碳密度影响的综合分析表明,DCA的第一排序轴与高山松林的碳密度相关性最大,可以很好地解释环境因子的综合作用对高山松林碳密度产生的影响,在26个环境因子中,有20个环境因子与DCA第一排序轴有极显著的相关性,其中,林分因子的相关性系数较大,说明高山松林的碳密度主要受林分因子共同作用的影响。

滇西北高山松根径立木材积表编制

为满足林政管理及理论研究需要,利用滇西北地区647株高山松编表样木数据,选用8种一元材积回归方程,拟合各模型参数,建立了高山松材积与根径回归模型,并用检验样本215株进行了适用性检验。结果表明,滇西北地区高山松材积与根径最佳模型为V=7.730919×(1^(-e-0.020279×DR))^(3.753409),相关系数(R^(2))为0.91,总相对误差(RS)为-0.20%,符合森林资源调查精度要求。在此基础上,编制了滇西北地区高山松根径立木材积表。

滇西北高山松根径与胸径相关性模型比选研究

在滇西北调查高山松样木总株数862株,有效样木824株,系统抽取建模样木618株,检验样木206株。选用10种一元线性或非线性回归方程,拟合各胸径D与根径DR模型参数,并进行了适用性检验。结果表明,模型D=-2.710599+0.938673DR-0.000911DR^(2),离差平方和(SSR)值相对较小、总相对误差(RS)为0、相关系数(R^(2))0.987、预估精度99.44%,残差图以横轴为中心分布最为均匀随机,模型参数变动系数最大值为32.3%,说明模型稳定。检验样本实测值和估计值没有显著差异,该模型最优。

云南3种松树径向生长的气候因子响应异质性

【目的】探究云南高原高山松、云南松和思茅松3种松树径向生长对区域气候因子的响应和适应性特征,为预测气候变化背景下西南林区树木生长动态及各树种地理分布区变化提供指导,为区域森林保护和管理提供理论依据。【方法】根据树木年轮学方法,采集各树种分布区内树轮样本,构建树轮宽度年表,结合各采样点1958—2018年的气温、降水、帕尔默干旱指数等气象资料,利用响应分析、多元回归分析和滑动相关分析等方法,确定影响3种松树径向生长的关键气候因子及其对气候变化的响应差异。【结果】3种松树采样点的气候均呈暖干化特征。限制松树径向生长的关键因子对高山松为当年5月降水量和1月平均气温,其对回归模型方差解释率的贡献分别达59.8%和27.5%;对云南松为上一年10月、12月和当年1月降水量,其对回归模型方差解释率的贡献分别达38.8%、15.4%和25.4%;对思茅松为当年生长季(7月)、上一年和当年生长季后期(9月)降水量,其对回归模型方差解释率的贡献分别达53.8%、30.9%和15.3%。云南松径向生长对干旱的敏感性高于高山松和思茅松。气候暖干化使高山松对生长季初期(5月)气温和降水量的敏感性增强;使云南松对生长季初期(5月)降水量的敏感性减弱,对生长季(8月)气温的敏感性增强;使思茅松对7月平均气温、平均最高温度的敏感性减弱,对上一年生长季后期(9月)降水量的敏感性增强。气候变暖使3种松树径向生长与气候因子的响应关系变得不稳定,主要发生在各采样点气候突变时间段,与区域气候波动同步,且不同树种具有一致性。【结论】高山松和思茅松对干旱的适应性强于云南松。气候变暖使气温对高海拔区高山松径向生长的促进效应减弱,使云南松对生长季初期低降水敏感转变为对生长季低温敏感;气候变暖抑制思茅松生长季充足水分条件的促生长作用,增强气候因子对径向生长影响的滞后效应,使3种松树对气候因子响应的敏感性变得不稳定。

基于无人机多光谱的高山松地上生物量估测

以机载数据替代卫星影像的方式提高森林生物量估测精度,是目前林业遥感研究的重点领域。以高山松(Pinus densata)林为研究对象,进行无人机(Unmanned Aerial Vehicle,UAV)多光谱影像数据采集;结合36块样地实测数据,采用变异函数确定高山松地上生物量最佳观测窗口;提取并筛选出相关性较强的5个因子,分别建立PLS和RF模型,对飞行区高山松地上生物量进行估测。结果表明,高山松地上生物量最佳观测窗口为球状模型的变程α值5.2 m;RF模型(R^(2)=0.90、RMSE=17.96 t/hm^(2)、P=84.98%)优于PLS模型(R^(2)=0.55、RMSE=38.94 t/hm^(2)、P=71.13%);基于RF模型,飞行区高山松地上生物量均值为130.48 t/hm^(2),总生物量为8343.53 t。

香格里拉市高山松林碳储量空间分异研究

以香格里拉市高山松林为研究对象,构建高山松单木碳储量模型,结合森林资源二类调查数据推算香格里拉市高山松林的碳储量和碳密度,以DEM为数据源,对研究区高山松林碳储量和碳密度的空间分布特征进行分析。研究结果表明,高山松单木碳储量模型以幂函数模型精度最高,决定系数R~2=0.989,均方误差MSE=259.43,可用来进行高山松林碳储量估测;在空间分布上,研究区高山松碳储量集中分布于海拔>2 500~4 000 m地段,在海拔>2 000~2 500 m地段碳储量密度最大,为40.80 t/hm^(2);高山松林碳储量从平坡到险坡的分布呈先增大后减小的趋势,其中,在陡坡上分布最多,在平坡上分布最少;高山松林碳密度随坡度的增大呈先增大后减小的趋势,其中高山松林在急坡上的碳密度最大,为35.94 t/hm^(2),在平坡上的碳密度最小,为30.85 t/hm^(2);高山松林碳储量在平地上分布极少,在阴坡、半阴坡、半阳坡、阳坡上的分布差异不大,呈先增大后减小的趋势,其中,在半阳坡上的分布最多,在阴坡上的分布最少,高山松林碳密度大小在各坡向上相差不大,在半阳坡上最大,为34.40 t/hm^(2),在平地上最小,为32.20 t/hm^(2)。

镉对高山松和高山栎盆栽中土壤动物多样性的影响

为了解金属镉污染过的土壤在种植不同高山木本后对土壤动物多样性的影响,本研究以三种浓度的金属镉对土壤进行处理,分别种植高山松和高山栎90 d后,用干漏斗法分离土壤动物。共捕获土壤动物2门7纲20目,其中真螨目、弹尾目为优势类群。结果表明:高山栎盆栽比高山松盆栽土壤中的物种丰富度更大,土壤动物数量更多。金属镉处理土壤后导致土壤动物群落结构趋于简单,土壤动物数量和土壤动物多样性降低。研究发现,一定浓度的金属镉处理后的土壤中,弹尾目和真螨目的动物在土壤动物群落中的数量变化不显著,说明弹尾目和真螨目动物可能对重金属镉具有一定的耐受性。

基于Landsat时间序列影像和AHTC算法的高山松地上生物量估测

【目的】为了提高高山松地上生物量估测的精度,开发一种滤波算法,减少Landsat时间序列数据的噪声。【方法】基于1987、1992、1997、2002、2007、2012、2017年国家森林资源连续清查固定样地的数据以及1987—2017年的Landsat时间序列影像,利用谷歌地球引擎(Google earth engine,GEE)以及Python,通过Land Trendr滤波、Savitzky-Golay滤波、Horn卷积以及基于空间卷积理论开发的自适应霍恩地形卷积(Adaptive horn topography convolution,AHTC)算法对Landsat时间序列数据进行滤波,应用随机森林回归算法(Random forest regression,R_(FR))构建香格里拉市高山松地上生物量估测模型,并选择最优估测模型对1987、1992、1997、2002、2007、2012、2017年高山松地上生物量进行反演制图。【结果】1)从图像的直接评价指标均方根误差(Root mean square error,RMSE)以及峰值信噪比(Peak signal-to-noise ratio,PSNR)来看,经过AHTC算法滤波后的图像质量最好;2)在使用R_(FR)方法的情况下,滤波后的数据均表现出比原始数据更高的估测精度;3)经过AHTC算法滤波后的时间序列数据对高山松地上生物量的估测效果最优,其决定系数R2为0.885、均方根误差RMSE为34.63 t/hm^(2)、预测精度P为60.75%、相对均方根误差r RMSE为43.59%;4)采用AHTC和R_(FR)方法反演结果分别为1 236万t(1987年)、1 155万t(1992年)、1 455万t(1997年)、1 330万t(2002年)、1 314万t(2007年)、1 345万t(2012年)、1 654万t(2017年)。【结论】使用AHTC滤波方法在一定程度消除了时间序列影像自身所携带的大量噪声和不确定性,有效地提高了时间序列影像的质量,同时也为提高高山松地上生物量遥感估测精度提供了一种新思路。

引入环境变量的香格里拉市高山松碳储量估测

森林碳储量是森林固碳能力的重要参考指标,准确估算森林碳储量对陆地碳循环具有重要意义。以香格里拉市1987—2017年Landsat TM/OLI遥感影像、森林资源连续清查数据和地形数据为主要数据源,利用Pearson相关性法、Spearman相关性法、Kendall’sτ相关性法、距离相关性法和决策树法筛选预测变量,并引入不同环境变量结合随机森林(RF)模型估测香格里拉市高山松碳储量。结果显示:(1)在不同方法筛选出的预测变量中,偏度、角二阶矩等纹理因子与高山松碳储量相关性最高;(2)通过决策树法筛选出的变量组合所构建的RF模型效果最优,其R^(2)为0.845,RMSE为10.076 t/hm^(2),rRMSE为29.254%,P为0.747;(3)引入环境变量后,精度都有不同程度提升,其中地表温度对模型精度的提升最高,其R^(2)提高了4.80%,RMSE降低了1.71 t/hm^(2),rRMSE降低了5.391%,P提高了6.60%;(4)1987—2017年,香格里拉市高山松碳储量时空变化较明显,高山松碳储量增加了651.266×10^(4)t。因此,不同的变量筛选方法会影响碳储量估测的准确性,同时引入环境变量能够提高模型估测精度,研究结果可为后续基于遥感的碳储量估测提供参考。

不同高山树种中重金属镉迁移富集研究

土壤中重金属的过量存在不仅破环土壤理化性状,影响植物的正常生长,而且通过食物链传递,也会影响人体的健康安全。本文通过外源添加镉(10 mg/kg、30 mg/kg、50 mg/kg)在盆栽土壤中,模拟自然条件下不同污染程度,采用富集系数、转运系数等指标分析重金属镉在高山松、高山栎两个高山地区特有树种中的污染特征,探究重金属在土壤-植物系统里的转移富集规律,为污染土壤实行生物修复提供一定依据。结果表明:(1)90 d以后,高山松、高山栎体内的镉含量与土壤中镉含量呈正相关,主要积累在地下部。(2)高山松地上部、地下部的富集系数随土壤镉浓度的增加均表现为先升后降,在镉处理浓度为30 mg/kg时达到最大;转运系数随土壤镉浓度的增加呈递增趋势。(3)高山栎地上部、地下部的富集系数与土壤镉浓度呈负相关,在镉处理浓度为10 mg/kg时最大;转运系数随土壤镉浓度的增加呈递减趋势。

川西高山松林火烧迹地植被天然恢复过程中物种多样性动态研究

以'空间序列'代替'时间序列'的研究方法对川西灌木高山松林不同年龄火烧迹地调查研究,结果表明:灌木高山松林火烧迹地恢复早期,物种多样性波动较大,其并非绝对随群落演替的顺向发展而增加,火烧后4～5年是群落发生剧变的时期,火烧后8～20年、20～27年是群落结构组成连续变化的时期,群落中物种多样性最大值出现在恢复27年时耐荫物种和不耐荫物种同时出现的阶段.

不同种群高山松1年生播种苗木生长节律及其变异

对高山松(Pinus densata)天然分布区内的8个种群苗高与地径生长量定株、定期观测,采用Logistic方程对其生长过程进行拟合,分析了高山松不同种群在理论亲本种云南松生境下1年生苗木生长节律及其变异。结果表明:①)发芽期结束后,苗高、地径生长呈现"慢-快-慢"节律,符合"S"型生长曲线,采用Logistic模型拟合效果显著,相关系数均在0.96以上;苗高、地径生长量的实测值与理论值回归系数分别为0.995 9和0.931 7,生长模型分析可行。②根据拟合方程获得物候参数,把苗高和地径生长期划分为生长前期、速生期和生长后期。不同阶段苗高、地径生长起、止时间存在差异,并表现出苗高与地径的异速生长现象。速生期苗高生长在前,地径生长在后。③不同种群苗期生长表现存在变异,苗高生长在生长前期、速生期、生长后期的持续时间和日均生长量分别为:28～48 d、0.11～0.18 mm,45～68 d、0.25～0.44 mm,110～151 d、0.04～0.09 mm;地径在各阶段的持续时间和日均生长量分别为40～89 d、0.003～0.004 mm,58～80 d、0.007～0.011 mm,61～113 d、0.002～0.004 mm。④速生期内的生长量占总生长量的比例较高,苗高、地径生长量比例分别为57.34%～57.93%和57.29%～58.47%,速生期内的苗高、地径生长量与整个生长期内的苗高、地径生长量呈显著的正相关关系(R为0.999 8和0.998 8),速生期起始时间与结束时间也存在显著正相关关系(R为0.859 2和0.815 1)。可见,高山松在理论亲本种云南松生境下苗期表现出正常的适应性,较早进入速生期的能迅速占据生长空间而获得较高的生长量,但不同种群间存在明显地分化,这与高山松的杂交起源特性及不同种群复杂的遗传背景有关。

藏东南高山松种群结构及动态特征

种群结构及数量动态是种群生态学研究的核心问题.种群结构包括水平结构和垂直结构,水平结构主要是指种群径级结构、年龄结构及冠幅结构,垂直结构主要是指种群的高度结构.种群结构不仅反映了种群不同个体的配置情况,也反映了种群数量动态及其发展趋势,并在很大程度上反映了种群和环境间的相互关系及它们在群落中的作用和地位（范繁荣等,2008）.静态生命表和存活曲线是进行种群统计和研究种群数量动态变化的重要工具,生存分析的4个函数（生存函数S（i）、积累死亡率函数F（i）、死亡密度函数f（ti）和危险率函数λ（ti））可以辅助种群生命表分析,

云南松及其近缘种的遗传变异与亲缘关系

The authors investigated the genetic diversity of 29 natural populations representing Pinus yunnanensis Franch. and its two close relatives, P. densata Mast. and P. kesiya Royle ex Gordn. var. langbianensis (A Chey.) Gaussen. Horizontal starch gel electrophoresis was performed for macrogametophytes collected from populations in Yunnan, Sichuan and Guangxi. Allozyme data for 33 loci of 14 enzymes demonstrated high levels of genetic variation at both population and species levels in comparison with other conifers, with the mean values for populations being P=0.694, A =2.0 and He =0.145 for P. yunnanensis; P=0.714, A=2.0 and He =0.174 for P. densata ; and P=0.758, A=2.1 and He =0.184 for P. kesiya var. langbianensis. Based on Wright’s F _statistics, the fixation index of P. yunnanensis, P. densata and P. kesiya var. langbianensis were 0.101, 0.054 and 0.143, respectively, indicating that the populations were largely under random mating. Based on Nei’s genetic distance, the genetic differentiation was not obvious among the three species (i.e. the genetic distance was less than 0.075). Because of the wider distribution of P. yunnanensis with greater variety of habitats, it was shown that the genetic differentiation among the P. yunnanensis populations was larger than that of the populations of the other two species. According to morphological, geographic and allozymic evidences, the authors suggested that the three species be better treated as varieties under a single species. In addition, the extensive gene flow among the three pine species resulted in great genetic diversity and evolutionary potential. Also, high level of genetic variation of P. yunnanensis provides important basis for its genetic improvement and breeding in future.