气候变化情景下祁连圆柏在青海省的适宜分布区预测

祁连圆柏具有良好的水土保持功能,是青海省高寒干旱地区造林绿化的优良乡土树种之一,预测未来气候变化情景下祁连圆柏在青海省的潜在地理分布将为祁连圆柏的经营管理和引种栽培提供理论指导。本研究基于实地调查和资料搜集获得88个有效地理分布样点,利用Maxent模型和ArcGIS空间分析技术对当前气候条件下祁连圆柏在青海省的潜在地理分布进行模拟,综合Jackknife检验和相关系数,分析影响祁连圆柏潜在分布的主导限制因子,同时结合第六次国际耦合模式比较计划(CMIP6)的气候模式数据,预测祁连圆柏在3种(SSP126、SSP245、SSP585)气候变化情景下2061—2080年潜在适生区的变化。结果表明:Maxent模型受试者工作特征曲线下面积(AUC)都大于0.92,具有较好的预测能力。在当前气候条件下,祁连圆柏的适宜分布区主要位于青海省东部,总适宜区面积占比为11.2%,影响其地理分布的主导因子是海拔、年均降水量、极端最低温和坡度,累计贡献率为85.9%。未来3种气候情景对祁连圆柏适宜区的影响存在差异,SSP245气候情景的适宜区面积将会缩减,SSP126和SSP585气候情景下则会不同程度地扩张,SSP126气候情景的扩张最明显,其扩张区域主要位于泽库县、河南蒙古族自治县中北部和祁连县东南部地区。在未来3种气候情景下,祁连圆柏适宜分布区逐渐向高海拔地区迁移,但在经纬度方向分布变化较小,适宜区总体稳定。     

气候变化对黄腹角雉潜在栖息地的影响

气候变化直接影响物种赖以生存的栖息地环境条件,进而影响物种的分布、数量和存活率。基于优化后最大熵(MaxEnt)模型预测气候变化下黄腹角雉(Tragopan caboti)过去、当前、未来时期的潜在栖息地格局。结果表明,降水量、温度、海拔是栖息地的主要影响因子。当前时期适宜栖息地面积较过去时期下降24.69%;未来2041—2060年间,共享社会经济路径(SSP)3-7.0与SSP5-8.5情景下黄腹角雉适宜栖息地面积较当前时期分别下降55.19%、58.10%。浙江、江西和福建是当前以及未来黄腹角雉核心适宜栖息地,适宜栖息地面积呈现下降的趋势,并往高纬度区域移动。     

基于最大熵模型的中国兜兰属植物潜在分布模拟

基于已知分布点和20个环境因子,该研究利用MaxEnt模型模拟在现在(1970—2000年)气候条件和2种不同共享经济路径情景下(SSP1-2.6、SSP5-8.5)未来(2081—2100年)兜兰属(Paphiopedilum)植物的潜在分布格局,找出影响物种分布的环境因子。结果表明,兜兰属植物的最适宜分布区位于滇东南地区、贵州西南、广西西部、广东南部、海南北部。影响该属植物分布的主要环境因子是年降水量、年温度变化和最干旱季降水量。随着全球变暖,适生区有向北和西北方向扩张的趋势,逐渐往西北亚热带方向延伸。在SSP5-8.5的情景下,高适生区出现大幅度收缩。在未来气候情景下,不同种群的分布区变化规律并不一致,其分布格局响应气候变化的趋势也有所不同,因此该文针对分布区变化趋势不同的物种提出了不同的保护策略。     

气候变化下寒露林蛙在中国的潜在地理分布

近几十年来,全球变暖对全球生物多样性及其地理分布产生了重要影响,特别是对气候变化敏感的两栖动物。寒露林蛙(Rana hanluica)是中国特有种,但在濒危物种红色名录中处于无危状态。为了评估寒露林蛙种群的生存现状,掌握该物种在中国的潜在分布区,以及在未来气候变化条件下适宜生境区的变化,本研究利用最大熵(MaxEnt)生态位模型和地理信息系统,对中国未来气候变化情景下(2050和2070年)寒露林蛙的适宜生境区进行识别。基于47个寒露林蛙分布位点和20个典型环境因子,建立了寒露林蛙在当前和未来气候条件下的适宜生境模型,并分析了相关的环境影响因子。结果表明: MaxEnt模型的预测准确度较高,受试者工作曲线面积值达0.993;寒露林蛙在当前气候条件下的潜在适宜生境面积为36.36万km²,潜在地理分布区域主要位于湖南省和贵州省;影响潜在地理分布的主要环境因子为最干月降水量和海拔。在未来2种典型浓度路径的气候情景下(SSP1-2.5和SSP5-8.5),寒露林蛙适宜生境区均出现不同程度的缩减,导致总适宜生境面积呈减少趋势;其高适宜生境向高纬度地区转移,其核心分布区仍以湖南省为主。     

气候变化对马尾松潜在分布影响预估的多模型比较

物种分布模型被广泛应用于评估气候变化对物种分布的影响。随着计算机和统计学的发展, 模拟物种分布的模型层出不穷, 但对这些模型的相对表现知之甚少, 因此需要对其进行对比分析, 以便更可靠地评估气候变化的影响。该文采用3个比较新颖的组合集成学习(ensemble learning)模型(随机森林(random forest, RF)、广义助推法和NeuralEnsembles)、3个常规模型(广义线性模型、广义加法模型和分类回归树)、3个大气环流模型(global circulation model, GCM) (MIROC32_medres, JP; CCCMA_CGCM3, CA; BCCR-BCM2.0, NW)和一个气体排放情景(SRES_A2), 模拟分析了马尾松(Pinus massoniana)历史基准气候(1961-1990)和未来3个不同时期(2010-2039, 2020s; 2040-2069, 2050s; 2070-2099, 2080s)的潜在分布。基于环境阈值方法选择物种不发生区, 依据ClimateChina软件进行当前和未来气候数据的降尺度处理, 采用接收机工作特征曲线(receiver operator characteristic, ROC)下的面积(area under the curve, AUC)、Kappa值和真实技巧统计法(true skill statistic, TSS)以及马尾松种子区划范围来评价模型的预测精度。结果表明: 6个物种分布模型都具有较高的预测精度, 但组合集成学习模型的预测精度稍高于其他常规模型, 其中RF的预测精度最高。3个GCM和6个模型模拟条件下, 马尾松对气候变化的响应格局既有一致性也有异同性。一致性表现在: 随着时间的推移, 马尾松分布区将逐渐向北迁移, 未来潜在分布区的面积将逐渐增加; 异同性表现在: 在不同模型和不同气候情景下, 马尾松潜在分布区的迁移距离和面积变化幅度不同, 其中NW模式下预测的变化幅度小于CA和JP模式; RF模型预测的分布区迁移距离和面积变化幅度最大。随着时间的推移, 未来马尾松的18个潜在分布空间预测图(6个模型 × 3 GCM)之间的差异也逐渐增大, 其中空间不一致性地区主要集中发生在马尾松潜在分布区的北部和西部边缘地带。模型本身不同的构建原理以及GCM之间的差异是导致预测结果存在差异的主要原因。     

气候变化背景下青藏高原藏羚羊生境时空格局演变

气候变化可能导致物种分布范围变化甚至导致物种灭绝。为了解气候变化对青藏高原旗舰种和濒危种-藏羚羊（Pantholops hodgsonii）的潜在分布区影响,收集了316个藏羚羊实际点位分布数据和70个文献点位分布数据与温度季节性变化（Bio4）,海拔,最干月降雨（Bio14）等9个影响因子,采用最大熵模型（MaxEnt）进行建模,预测SSP126、SSP585极端压迫情景和SSP245中间压迫情景下的T1（2001-2018年）,T2（2021-2040年）,T3（2041-2060年）,T4（2061-2080年）,T5（2081-2100年）5个时期的潜在分布区。研究结果表明：（1）在不同气候变化情景下,藏羚羊核心生境主要分布在可可西里、羌塘、阿尔金国家级自然保护区和三江源国家公园;（2）温度季节性变化（Bio4）和海拔被认为是最关键的两个环境因子;（3）随着温室气体排放强度的增强,藏羚羊的核心区生境向高海拔和高纬度地区扩张;（4）有43.18%的保护空缺区在保护区外,未受到有效保护。总之,研究藏羚羊的地理分布对于气候变化的响应与适应,根据适宜生境演变规律做出有效的保护措施,对藏羚羊种群的长期监测、保护、有效管理甚至重建具有重要现实意义。     

气候变化和人类活动干扰下骆驼刺潜在分布格局变化特征

气候变化和人类活动是影响物种分布的最重要因素。骆驼刺是我国荒漠区的重要建群种,建群种的丧失将对荒漠生态系统产生严重损伤。因此预测气候变化和人类活动影响下骆驼刺适宜生境的变化特点对保护我国荒漠生态系统具有重要的意义。本研究采用61个骆驼分布点数据,和21个环境因子数据,运用最大熵模型（MaxEnt）预测骆驼刺当前在有、无人类活动干扰下的适宜生境分布,对影响其分布的环境因素进行了评估。并预测未来（2021-2040,2041-2060,2061-2080,2081-2100）四条共享社会经济路径（SSP126,SSP245,SSP370,SSP585）情景下,骆驼刺潜在分布区的变化特点。研究结果表明,在无人类活动干扰的情况下,骆驼刺适生区面积达132.29万km²,覆盖我国西北干旱区的大部分面积。年均降水量、最冷季度平均温、平均气温日较差、年均温、温度季节性、降水的季节性和高程被确定为影响骆驼刺潜在分布区的最重要因素。而在加入人类活动强度因素之后,骆驼刺适生区面积显著下降至71.31万km²,且呈现出破碎化状态。此时,年降水量、人类活动强度和高程是影响骆驼刺分布的最重要原因。在未来气候情景下,骆驼刺的适生区将产生一定的扩张。尤其在中高强迫（SSP370）和高强迫（SSP585）情景下,骆驼刺的适生面积将随时间推移产生显著的增加,且这种扩张主要向高纬度和高海拔地区发展。骆驼刺能保留大部分原有生境,仅在内蒙古中西部地区发生少量收缩。在气候变化条件下,骆驼刺能够在西北干旱区生存并扩张,故可将其作为防沙治沙的优良物种进行保护与开发。     

中国三种常见蒿属植物潜在地理分布及其主导气候因子

裂叶蒿(Artemisia tanacetifolia)、大籽蒿(Artemisia sieversiana)和艾(Artemisia argyi)是我国常见的蒿属(Artemisia)植物,其分布区域遍布全国。本文利用MaxEnt模型预测3种蒿属植物在当前气候条件以及未来两种气候情景下的潜在分布区。采用受试者工作特征曲线(receiver operating characteristic curve,ROC)检验模型精度。训练数据和测试数据的AUC值均在0.8以上,表明预测结果可靠性良好。在当前的气候条件下,裂叶蒿最适分布区主要为黄土高原、内蒙古高原和东北平原;大籽蒿的最适分布区为西藏南部谷地、横断山地区、黄土高原、内蒙古高原和东北平原;艾的最适分布区有两个,一个位于台湾岛南部,另一个为大巴山、巫山、云贵高原北部、黄土高原和东北平原南部区域。2070年RCP2.6和RCP8.5情景下,裂叶蒿及大籽蒿的高适宜区面积减小,艾的最适分布区面积增加。Jackknife检验结果表明,年均降水量是预测裂叶蒿分布最有效的气候因子,5月降水是预测大籽蒿分布的最显著的气候因子,8月水汽压对艾的影响最大。本研究结果为蒿属植物资源的合理利用提供了科学依据。     

气候变化对东北濒危动物驼鹿潜在生境的影响

气候变化是造成生物多样性下降和物种灭绝的主要因素之一。研究气候变化对物种生境,尤其是濒危物种生境影响对未来保护物种多样性和保持生态系统功能完整性具有重要意义。以驼鹿乌苏里亚种(Alces alces cameloides)为研究对象,选取了对驼鹿分布可能存在影响的22个环境因子,利用最大熵(Maxent)模型模拟了驼鹿基准气候条件下在我国东北的潜在生境分布,并预测了RCP4.5和RCP8.5两种气候变化情景下2041—2060年(2050s)、2061—2080年(2070s)驼鹿潜在分布,采用接收工作曲线下面积(AUC)对模型预测能力进行评估。研究结果表明:最大熵模型预测驼鹿潜在生境分布的精度较高(平均AUC值为0.845),22个环境因子中,年均温、最暖季均温、年降水、平均日较差是影响驼鹿生境分布的主要因子。基准气候条件下,驼鹿的潜在生境面积占研究区域总面积的36.4%,潜在生境分布区主要在大、小兴安岭。随着时间的推移,研究区内驼鹿当前潜在生境面积明显减少,而新增潜在生境面积较少,总面积呈现急剧减少的趋势,其中RCP8.5情景减少程度大于RCP4.5情景。至2050s阶段,当前潜在生境面积平均将减少62.3%,新增潜在分布面积平均仅为3.6%,总潜在生境面积最高将减少65.6%,平均将减少58.8%;至2070s阶段,当前潜在生境面积平均将减少75.8%,新增潜在分布面积平均仅为1.9%,总潜在生境面积最高将减少93.1%,平均减少73.9%。空间分布上,驼鹿的潜在生境的几何中心将先向西北移动,然后再向高纬度地区西南方向迁移,至2050s阶段,潜在分布生境的几何中心在RCP4.5和RCP8.5情景下的迁移距离分别为183.5 km和210.8 km;至2070s阶段,相应情景下的迁移距离将缩短至28.7 km和33.8 km。潜在生境分布整体呈现向高海拔、高纬度迁移的趋势。     

气候变化对中国近海8种中上层鱼类潜在生境分布的影响

随着底层和近底层渔业资源的衰退,海洋中上层鱼类在我国海洋捕捞业中逐渐占据重要的地位。预测气候变化情景下中上层经济鱼类的潜在生境分布及其变化规律,可为应对气候变化的鱼类栖息地保护和渔业生态系统管理提供重要科学依据。采用物种分布模型模拟并预测现状及2050年两种气候变化情景下8种中上层经济鱼类在中国近海的潜在分布,通过分布区的收缩-扩张情形和质心迁移距离定量分析气候变化对鱼类空间分布格局的影响。结果表明：(1)模型预测结果良好,各组模型的AUC值均高于0.85,影响目标鱼类潜在分布的主要驱动因子为海水表层温度和溶解氧;(2)8种中上层经济鱼类中,羽鳃鲐(Rastrelliger kanagurta)、鳓鱼(Ilisha elongata)等种类生境分布偏南,气候变化情景下分布北界可扩展至长江口,而鳀鱼(Engraulis japonicus)、青鳞小沙丁鱼(Sardinella zunasi)等种类主要分布在我国北方海域,气候变化情景下生境南缘边界退缩明显;(3)整体来看RCP8.5情景下的空间分布变化率大于RCP2.6情景,其中蓝圆鲹(Decapterus maruadsi)、青鳞小沙丁...     

念珠藻属植物nifH基因的适应性进化分析

念珠藻(Nostoc)固氮过程关键在于固氮酶的催化,而固氮酶复合物中的铁蛋白(NifH)是由高度保守的nifH基因编码的,该基因是进化史上现存最古老的功能基因之一。该研究选取念珠藻属及近缘类群的nifH基因序列共40条,采用最大似然法构建系统发育树;运行PAML4.9软件,对nifH基因编码蛋白进行生物信息学分析,并使用分支模型、位点模型和分支-位点模型检测该基因的选择位点,探讨nifH基因的适应性进化特征。结果表明:(1)最大似然树显示内类群中该研究物种共分为6个分支(A、B、C、D、E和F),其中D和E是2个大的分支,每个大分支中又各包含2个特殊的小分支A、F和B、C,其中F分支包含新疆古尔班通古特沙漠采集到的9株念珠藻,A分支包含F分支及该研究测定序列的4株葛仙米,B分支包含本研究测定序列的4株地皮菜和3株未定种的念珠藻,C分支包含NCBI数据库中下载的5株念珠藻、鱼腥藻序列和本研究测定序列的1株念珠藻。(2)在所分析的3种进化模型中,仅通过分支-位点模型检测出14个统计学上显著的正选择位点,即1F、2S、3S、4T、5A、6F、7F、8I、9S、10C、17I、27Y、29D和31R位点,表明念珠藻属植物的nifH基因发生了适应性变化,分支-位点模型是研究藻类基因适应性进化较好的模型。     

The clam sipho as indicator for growth indices in the soft-shell clam <Emphasis Type="Italic">Mya arenaria</Emphasis>

Due to the species’ deep burrowing behaviour, growth parameters of the soft-shell clam Mya arenaria L. 1758 are difficult to estimate, especially in deeper habitats which are not directly accessible. In this study, we analysed 192 specimens of M. arenaria and found, contrary to results of most other studies that the sigmoid Gompertz growth model (GGM) is appropriate to describe the growth. Predictions from this model confirm the finding of a life span up to 8 years and as a consequence of this, a maximum shell-length of 60 mm. Individual growth rates calculated from the first deviation indicate a nearly exponential growth in young individuals. The relationship between the clam sipho-width and age, shell-length and biomass conform to the GGM. This is a new approach to assess growth of M. arenaria and to solve practical problems that arise in field studies.     

Critical evaluation of the VSC model for tip growth

The vesicle supply centre (VSC) model (Bartnicki-Garcia et al., 1989) for hyphal tip growth is powerful because it can model diverse developmental morphologies and predicts cellular organization based in current cell biology. It predicts that tip growth results from the random distribution of cell surface synthesizing vesicles from a point in the tip, the VSC, which determines their pattern of impact and fusion at the plasma membrane. We derive equations for tip-high gradients of vesicle fusions, generated by mechanisms not related to a supply centre, which create typical hyphal morphologies. These equations direct the conceptual basis for tip growth to vesicle fusion gradients, presumably mediated by a putative membrane skeleton associated with the plasma membrane. We also show that the organization and behaviour of motile organelles in growing hyphal tips of the oomycete,Saprolegnia ferax, argue against the presence of an apparatus capable of generating the distribution of vesicles postulated by the VSC model. We conclude that the VSC model is unlikely to describe the mechanistic basis of tip growth inS. ferax, and therefore, at best, it is not universally applicable.     

大黄属(蓼科) 植物ｎｄｈＦ 基因的适应性进化

大黄属(Rheum L.)是蓼科(Polygonaceae)中一个高度分化的大属,广泛分布在亚洲和欧洲的高山和沙漠地区,全世界约60种,其中在青藏高原及其邻近地区发现了约40种。该属种的高度分化曾被推测是第三纪末青藏高原的快速隆升以及第四纪气候的反复变化所引发的适应性辐射导致。为进一步了解大黄属植物辐射式物种分化的分子适应机制,该研究选取34个形态上多样化的大黄属物种,利用系统发育分析软件,在时间框架下采用位点模型和分支模型对大黄属的叶绿体ndhF基因进行了适应性进化分析。结果表明：大黄属植物的分子进化系统树呈现短而平行的辐射式分支式样,显示出典型的物种快速辐射多样化特征;用位点模型检验ndhF基因是否存在经受正向选择(ω>1)时,在氨基酸水平上共鉴定出3个NDHF亚基的正选择位点(188H,465H,551L),对NDHF亚基的二级结构进行分析后发现编码的188H氨基酸位于α螺旋上。大黄属植物可能通过这些结构域的适应性进化,适应青藏高原的快速隆升以及第四纪气候的反复变化而引发的陆地生态系统改变。该研究结果可为今后对该属植物的实验分析提供首选位点。     

A population model for Dermanyssus gallinae (Acari: Dermanyssidae)

A model based on a time-varying distributed delay with attrition was developed for simulating the population dynamics of the chicken mite Dermanyssus gallinae (DeGeer, 1778). The model was parametrised according to cohort life table studies conducted under constant temperature conditions and was validated with two independent data set obtained in an experimental poultry house. The predicted mite densities and the stage-structure of the population corresponded to the values observed during experimental periods of 32, and 11 weeks, respectively. Temperature and a poultry house-specific density effect were determined to control the population development.     

Projecting population-level response of purple sea urchins to lead contamination for an estuarine ecological risk assessment

As part of an ecological risk assessment casestudy at the Portsmouth Naval Shipyard (PNS), Kittery,Maine, USA, the population level effects of leadexposure to purple sea urchin, Arbaciapunctulata, were investigated using a stage-classifiedmatrix population model. The model divided the lifehistory of A. punctulata into five classes,incorporating both, the developmental stages of thisspecies and the endpoints from a laboratory bioassay. Finite population growth rate () was themetric relating population level impact to leadexposure. An inverse relationship was observed betweenlead tissue residues in A. punctulata and. Bioassay treatments which resulted insignificant impacts on fertilization success and zygoteviability did not translate into significant effects on, unless those treatments also negativelyimpacted adult survival. These results paralleled theelasticity (relative sensitivity) analysis of themodel, which indicated that was mostsensitive to adult and subadult survival and wasrelatively insensitive to fecundity, fertilizationsuccess, or zygote survival. Model results indicatedthat the environmental lead levels observed at PNSshould not pose significant ecological risk to seaurchin populations. Additionally, the model resultsindicated that impacts to the early life stagesroutinely used in toxicity testing do not necessarilytranslate directly into impacts at the populationlevel.     

Individual-based modelling of Pinus sylvestris invasion after grazing abandonment in the French Massif Central

In the Chaîne des Puys, a mid-elevation volcanic mountain of the French Massif Central, Scots pine proves to be an invasive species colonizing abandoned lawns or heathlands, and forms in a few years monospecific natural forests. Most of the abandonment occurred 30 to 40 years ago and this process has now stopped. Thus, we lack data on the very first phase of tree colonization. We anticipate that a simulation tool could bring an appreciable help in (i) rebuilding the entire colonization process – including the initial phase – of pine settlement and (ii) answering questions about the origin of the narrow and unimodal distributions of age of pine stands we observed. In addition, such a simulator could help managers to forecast extension of Scots pine and to predict growth and evolution of present secondary forests. A spatially explicit individual-based model is presented. The model takes into account both space and time and includes growth of trees, seed production and seed dispersal, death and competition between individuals. The influence of the initial parameters are analyzed and elements of validation given. The model was then used to predict tree settlement and stand establishment using the initial conditions from a natural stand studied in the field whose characteristics before abandonment were known (number and age-distribution of trees, location of mother trees, time of abandonment). Three simulations were achieved by using the same initial conditions but following different scenarios for the recruitment process. The scenario of a fluctuating resistance of the resident vegetation (that controls the susceptibility of the environment to tree establishment) seemed as one of the most probable to explain the actual stand characteristics. We thus concluded that dynamic models could be improved by taking into account the resistance of the vegetation to colonization as a fluctuating parameter instead of a static and permanent attribute.     

Plant competition for light analyzed with a multispecies canopy model

Summary Competition for light among species in a mixed canopy can be assessed quantitatively by a simulation model which evaluates the importance of different morphological and photosynthetic characteristics of each species. A model was developed that simulates how the foliage of all species attenuate radiation in the canopy and how much radiation is received by foliage of each species. The model can account for different kinds of foliage (leaf blades, stems, etc.) for each species. The photosynthesis and transpiration for sunlit and shaded foliage of each species is also computed for different layers in the canopy. The model is an extension of previously described single-species canopy photosynthesis simulation models. Model predictions of the fraction of foliage sunlit and interception of light by sunlit and shaded foliage for monoculture and mixed canopies of wheat (Triticum aestivum) and wild oat (Avena fatua) in the field compared very well with measured values. The model was used to calculate light interception and canopy photosynthesis for both species of wheat/wild oat mixtures grown under normal solar and enhanced ultraviolet-B (290–320 nm) radiation (UV-B) in a glasshouse experiment with no root competition. In these experiments, measurements showed that the mixtures receiving enhanced UV-B radiation had a greater proportion of the total foliage area composed of wheat compared to mixtures in the control treatments. The difference in species foliage area and its position in the canopy resulted in a calculated increase in the portion of total canopy radiation interception and photosynthesis by wheat. This, in turn, is consistent with greater canopy biomass of wheat reported in canopies irradiated with supplemental UV-B.     

Forecasting spore concentrations: A time series approach

Fungal basidiospores andCladosporium spores are the two most numerous spore types in the air of Dublin and its surroundings. They are known to have allergenic components, and the aim of the study described here is to develop a predictive model for these spores. A very simple model, which combines an estimated diurnal rhythm with a simple, one-parameter time series model, provided golld short-term forecasts. The one-step prediction error variance was reduced by 88% forCladosporium spores and by 98% for basidiospores.     

不同施肥方法对马来沉香和土沉香苗期根系生长的影响

以珍贵树种马来沉香、土沉香1年生播种苗木为材料进行试验,研究指数施肥、平均施肥对2种沉香苗期根系生长动态及对N的响应特征。结果表明,经氮素处理的马来沉香、土沉香的根系生物量、根系长度、根系表面积、根系平均直径、根体积等指标均显著高于对照处理(P<0.05)。经指数施肥处理的苗木根系生长及各形态指标均高于平均施肥处理。同一时期在相同施肥处理方式下,马来沉香苗根系生长及根系形态指标值均高于土沉香。洛伦兹模型对不同施肥方法处理下马来沉香、土沉香苗木生长指标与根系生物量进行拟合,具有较高的R²(0.95-0.99)和较低的RSMD(0.538-2.352);抛物面模型对不同施肥方法处理下马来沉香、土沉香苗木生长指标与比根长进行拟合,具有较高的R²(0.92-0.99)和较低的RSMD(3.218-6.692)。