Analysis of Genetic Structure of Natural Populations of Castanopsis fargesii by RAPDs

Genetic diversity and population genetic structure in 188 individuals from five natural populations of Castampsis fargesii Franch. were studied by RAPD markers. Three hundred and eighty-five loci were identified with 41 oligonucleotide primers, out of which 157 loci were polymorphic and accounted for 40.78% of total genetic diversity at species level. Shannon's indices of diversity (I) and Nei's gene diversity ( h) were 0.459 7 and 0.296 at the species level, respectively. The result showed that genetic variation of C. fargesii populations mainly existed within populations. Genetic differentiation (Hsp-hpop)/Hsp estimated with Shannon's index of diversity and coefficient of gene differentiation (Gst) were 0.047 6 and 0.042 9 respectively, which were confirmed by the analysis of molecular variance (AMOVA). Therefore, it is apparent that within-population variation accounted for 94.97% and among-populations variation accounted for only 5.03% of the total genetic diversity. AMOVA also indicated that there was significant differentiation among populations as well as among individuals within a population.

不同干扰背景下栲树(Castanopsis fargesii)幼苗幼树的生理生态特性比较——以浙江天童常绿阔叶林为例

浙江天童国家森林公园的常绿阔叶林在我国东南沿海地区具有代表性,在研究区内设置不同干扰方式下的5块样地,借助LI-6400型便携式光合测定系统对研究区内不同干扰背景下5块样地常绿阔叶林主要优势种之一的栲树幼苗、幼树的光合生理生态特性进行了测定。比较了不同干扰背景下栲树幼苗、幼树的净光合作用速率、蒸腾作用速率、水分利用效率、表观量子效率等生理生态指标。结果表明,去除乔木层的样地1,2,3中栲树幼苗、幼树的净光合速率与蒸腾速率要高于仅保留乔木层的样地4和对照样地5,水分利用效率和表观量子效率则低于样地5和样地4。应用统计分析软件对净光合作用速率与诸生理生态影响因子的相关性进行分析,同时使用逐步回归的方法建立光合速率和诸影响因子之间的回归方程模型,栲树幼苗:Pn=-2.399+0.205Ta+43.209Gs,栲树幼树:Pn=-2.265+0.006PAR-3.915Vpdl+0.364Ta+38.121Gs,在α=0.05水平上,两个方程均有显著性意义,有良好的预测性。

Characters and Species Diversity of Torreya fargesii Franch. Community in the Jinfo Mountains

This paper aims to study characteristics and biodiversity of the Torreya fargesii community in the Jinfo Mountains to provide baseline information related to the protection of T. fargesii. The results indicated that among the 5 plots(100 m2 each) set along an altitudinal gradient, 176 species of vascular plants, 136 genera and 64 families were recorded. These included 7 species of pteridophytes, 6 genera and 4 families, 3 species of gymnosperms, 3 genera and 2 families, and 166 species of angiosperms, 127 genera and 58 families. The community physiognomy was mainly dominated by phanerophytes with medium-sized herbaceous and simple leaves. The proportions of phanerophytes among the fl oristic spectrum, frequency spectrum and vegetational spectrum are 68.75%, 73.13% and 67.48% respectively. The vertical structure can be divided into the shrub and herb layers in this community. The dominant species in shrub layer were T. fargesii, Zanthoxylum ovalifolium, Rubus coreanus, Kerria japonica, Cotoneaster horizontalis etc.. The dominant herbs included Miscanthus sinensis, Carex gibba, Artemisia lactifl ora, Pteridium aquilinum var. latiusculum, Pilea notata, Aster ageratoides etc.. Species richness(S) and the Simpson(D), Shannon-Wiener(H') and Pielou evenness(Jsw) indices of shrub layer species richness are higher than those of the herb layer; the distribution of the species in the community is obviously uneven. The species richness and diversity indices increase with the rising altitude.

Analysis of spatiotemporal variations in the characteristics of soil microbial communities in Castanopsis fargesii forests

Castanopsis fargesii is a good afforestation plants and various microorganisms play important roles in mediating the growth and ecological functions of this species.In this study,we evaluated changes in microbial communities in soil samples from C.fargesii forests.The phospholipid fatty acid(PLFA)biomarker method was used to obtain bacteria,fungi,actinomycetes,gram-positive bacteria(G?),gram-negative bacteria(G-),aerobic bacteria,and anaerobic bacteria to investigate spatiotemporal changes in microbial communities during the growing season.The results show that soil microorganisms were mainly concentrated in the upper 20-cm layer,demonstrating an obvious surface aggregation(P<0.05).Large amounts of litter and heavy rainfall during the early growing season resulted in the highest PLFA contents for various microorganisms,whereas relatively low and stable levels were observed during other times.The dominant species during each period were bacteria.G+ or aerobic bacteria were the main bacterial populations,providing insights into the overall trends of soil bacterial PLFA contents.Due to the relative accumulation of refractory substances during the later stages of litter decomposition,the effects of fungi increased significantly.Overall,our findings demonstrate that the main factors influencing microbial communities were litter,rainfall,and soil field capacity.

阔叶材新干燥法研究——栲树(Castanopsis fargesii)干燥

本文从原料的制备、工艺试验以及质量分析,研究栲树的热板干燥。研究结果表明,尽管木材的含水率和干燥工艺参数不同,板材都能在1～4h内干燥到终含水率为6％左右。年轮角度影响干燥期间的蜂窝裂;热板压力与厚度收缩变化关系显著,板材初含水率高也会增加干燥时的厚度收缩;温度和压力对干燥速度有较大的影响;干燥终了存在微小的皱缩,但不会导致板材的降级。综合考虑,适宜的栲树热板干燥工艺为:温度160℃,压力7MPa。

Allelopathic Effects of Aqueous Extract of Torreya fargesii Aril on Seed Germination and Seedling Growth of Radish, Mustard and Cabbage

[Objective] This study aimed to investigate the allelopathic effects of Torreya fargesii aril. [Method] By indoor bioassay, the effects of different con-centrations （10, 20,40, 80 g/L） of aqueous extract of T. fargesii aril on seed germination rate, seedling root length, seedling height, fresh weight, chlorophyll content, malondialdehyde （MDA） content and anti oxidative enzyme activities of radish, mustard and cabbage were analyzed and compared. [ Result] Different concentrations of aqueous extract of T. fargesii aril inhibited seed germination and seedling growth of three crops, and the inhibitory effects were enhanced with the increase of concentration. Seedling height and fresh weight of three crops were improved by low concentrations of aqueous extract of T. fargesii aril and inhibited by high concentrations of aqueous extract. Overall, aqueous extract of T. fargesii aril exhibited allelopathic inhibitory effects on three crops, and the level of allelopath-ic inhibitory effects demonstrated a descending order of radish 〉 mustard 〉 cabbage. Compared with the control group, 80 g/L aqueous extract of T. fargesii aril almost significantly reduced seed germination rate, seedling root length, seedling height, fresh weight and chlorophyll content, and significantly improved MDA con-tent and antioxidative enzyme （SOD, CAT, POD） activities of radish, mustard and cabbage （P 〈 0 .0 5 ） . [ Conclusion] Aqueous extract of T. fargesii aril exhibited remarkable allelopathic inhibitory effects on seed germination of radish, mustard and cabbage, which indicated that there might be dormancy-associated germination in-hibiting allelochemicals in T. fargesii aril. This study provided theoretical basis for subsequent clarification of the mechanism of seed dormancy of T. fargesii.

Responses of Leaf Functional Traits of Torreya fargesii to the Altitudinal Variation

[Objective] To reveal the leaf functional traits and adaptive strategy of Torreya fargesii at different altitude gradients.[Method] Leaves of T. fargesii were selected from the altitudes of 1 570, 1 700, 1 900, 2 125 and 2 360 m in Jiajinshan forest area of Sichuan Baoxing County, and the altitudes of 1 000, 1 200, 1 450, and 1 700 m in Hua'eshan Mountain Nature Reserve of Sichuan Wanyuan County as the research materials. Leaf blade traits such as leaf length, leaf width, leaf girth, leaf area and leaf dry weight were determined, and the influence of altitude on each index and correlation between characters were analyzed. [Result] For the leaves from both Baoxing County and Wanyuan County, leaf length, leaf width, leaf girth, leaf aspect ratio and leaf area decreased with the increase of altitude. There was no significant difference in the changes of leaf width, leaf girth and leaf aspect ratio among different altitudes(P>0.05), while the difference was significant in leaf length between high altitude and low attitude(P<0.05), and the difference was also significant in leaf area for the leaves from Baoxing County between high altitude and low altitude. However, there was no obvious correlation between leaf width and altitude, which could be considered as a relatively stable parameter. Leaf thickness and leaf dry weight increased first and then decreased with altitude,while the specific leaf area decreased first and then increased. In leaf length, leaf girth, leaf width and leaf area parameters, except for leaf width and leaf area for the T. fargesii from Wanyuan County, any two parameters reached significant or very significant positive correlation level(P<0.01). Leaf dry weight and leaf thickness had significant or very significant positive correlation, leaf dry weight and leaf area had a certain positive correlation but not significant. There existed no significant positive correlation between specific leaf area and leaf area, while specific leaf area was in negative correlation with leaf dry weight, and the negative correlation of specific leaf area with leaf area of T. fargesii from Wanyuan County reached the significant level.[Conclusion] T. fargesii adapted to different altitudes by changing leaf dry weight, leaf area and leaf area ratio, and the most suitable altitudes for the growth of T. fargesii were 1 900 and 1 450 m in Baoxing and Wanyuan area respectively.

Timing of germination in the subtropical chinese tree Castanopsis farqesii

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郭岩山不同海拔天然栲树林土壤硅形态特征

[目的]探究郭岩山不同海拔天然栲树林土壤硅形态的变化特征及其与土壤理化性质的相关关系,进一步揭示亚热带地区土壤硅形态含量对环境变化的响应机制。[方法 ]本研究以郭岩山自然保护区不同海拔天然栲树林土壤为研究对象,在郭岩山自然保护区海拔600、700、800、900 m分别设置标准地,采集不同海拔各土层(0~20、20~40、40~60 cm)的土样,测定土壤不同硅形态含量,分析环境变化对土壤中硅形态的影响。[结果 ](1)高海拔土壤有效硅(258.26 mg·kg^(-1))、水溶性硅(155.69 mg·kg^(-1))、活性硅(388.97mg·kg^(-1))及无定形硅(1 561.97 mg·kg^(-1))含量均显著高于低海拔土壤有效硅(93.16 mg·kg^(-1))、水溶性硅(78.38 mg·kg^(-1))、活性硅(231.84 mg·kg^(-1))及无定形硅(832.24 mg·kg^(-1))。深土层(40~60 cm)的土壤有效硅含量(227.53 mg·kg^(-1))显著高于0~20 cm(120.79 mg·kg^(-1))及20~40 cm(171.37 mg·kg^(-1))土层;(2)土壤有效硅含量与活性硅及水溶性硅含量呈极显著正相关,其中,活性硅是有效硅增加最重要的直接贡献形态,而水溶性硅是土壤硅转化过程中重要的过渡性形态;(3)土壤有机质和土壤pH值对各土壤硅形态含量的影响最显著,解释率分别达14.1%和9.2%,其中,土壤有机质与无定形硅及水溶性硅呈正相关,与土壤活性硅及有效硅呈负相关,而土壤pH值与有效硅、活性硅呈正相关,与无定形硅呈负相关。[结论 ]海拔引起的环境及土壤理化性质变化可改变土壤硅形态含量。研究结果为天然栲树林有效利用土壤硅及调控土壤硅形态提供了参考依据,对天然栲树林的保护具有重要的科学指导意义。

郭岩山自然保护区丝栗栲天然林分土壤微生物群落沿海拔梯度变化

[目的]沿着海拔梯度探究郭岩山丝栗栲天然林分土壤微生物多样性和群落组成变化及其与土壤性质的相关关系,揭示气候变化对中国中亚热带中低海拔小跨度梯度下丝栗栲土壤微生物多样性和群落组成变化规律及其影响因素。[方法]选取郭岩山自然保护区海拔500~900 m梯度下丝栗栲天然林分的表层土壤,测定其理化性质,并进行Illumina高通量测序,采用相关性分析和冗余分析等方法研究土壤微生物多样性和群落组成特征及其影响因素。[结果]土壤细菌α多样性并没有呈现明显的海拔分布格局,而真菌的α多样性沿海拔梯度先下降后上升,这与大跨度海拔梯度的研究存在差异;酸杆菌门(Acidobacteria)、放线菌门(Actinobac-teria)和变形菌门(Proteobacteria)是细菌群落的3个主要菌门,norank_f_norank_o_subgroup_2、nor-ank_f_xanthobacteraceae是细菌群落的两个主要菌属;担子菌门(Basidiomycota)、子囊菌门(Ascomyco-ta)是真菌群落的两个主要菌门,Russula、Lactifluus是真菌群落的两个主要菌属,说明了小跨度的海拔梯度不会显著影响优势微生物菌门和属的变化;优势细菌门及属相对丰度及群落组成与土壤pH值、全磷和碱解氮密切相关,而土壤全磷和速效钾是影响真菌群落组成和优势门及属相对丰度的最重要因素,土壤性质可以很好地预测土壤微生物群落的变化,即使在小跨度海拔梯度上亦是如此。[结论]土壤性质和海拔高度共同影响了郭岩山自然保护区土壤微生物的生态地理学分布。本研究将为南方亚热带常绿阔叶林小跨度海拔梯度土壤微生物多样性研究和群落组成保护提供科学依据。

郭岩山不同海拔丝栗栲叶片养分回收特征分析

【目的】研究郭岩山自然保护区不同海拔丝栗栲(Castanopsis fargesii)天然林分的叶片(鲜叶和凋落叶)养分元素含量和回收率随海拔的变化特征,以期进一步了解丝栗栲养分元素循环机理和对环境的适应特性,为丝栗栲等亚热带常绿阔叶树种培育及外源养分调控提供参考。【方法】采集郭岩山自然保护区不同海拔(600~900 m)丝栗栲天然林的鲜叶和凋落叶,测定其氮(N)、磷(P)、钾(K)、钙(Ca)、镁(Mg)含量,并计算其回收率,采用皮尔逊(Pearson)相关分析探究不同海拔叶片养分元素之间的相关性。【结果】①海拔对丝栗栲鲜叶N、K、Ca、Mg元素含量和凋落叶N、Ca、Mg元素含量存在明显影响,凋落叶除Ca元素含量高于鲜叶外,其余元素含量均低于鲜叶;②相关性分析表明,在鲜叶中,K与P元素含量呈极显著正相关(P<0.01),与Mg元素含量呈显著负相关(P<0.05);而在凋落叶中,Mg元素含量与N和Ca元素含量之间存在显著和极显著正相关关系,K元素含量与Ca和Mg元素含量均存在显著负相关关系(P<0.05);③丝栗栲鲜叶与凋落叶间,Mg元素含量呈极显著负相关(P<0.01),N、K、Ca元素含量均呈极显著正相关(P<0.01),P元素含量相关性不显著(P>0.05);④N、K、Mg元素回收率受海拔影响显著,N和Mg元素回收率在800和900 m海拔处较低,K元素与之相反,P元素在不同海拔均具有较高回收率,而Ca元素不具有回收特征。【结论】丝栗栲叶片不同养分元素含量随海拔的变化存在差异且具有一定相关关系,在不同海拔条件下,丝栗栲叶片会对除Ca元素以外的N、P、K、Mg 4种养分元素予以回收,但回收率表现特征不同,在森林经营过程中可据此因地制宜控制N肥施用及改良元素配比,以满足林木生长发育需要。

缙云山常绿阔叶林栲种子产量及形态特征年际动态

种子产量和种子形态特征是反映植物繁殖潜力及适应能力的2个重要生物学指标。从种群尺度和个体尺度分析缙云山常绿阔叶林优势种栲种子产量及其形态特征的年际差异及个体差异,在此基础上进一步讨论栲的繁殖策略,以期为植物结实动态的大尺度研究提供数据支持。研究基于2013—2021年缙云山常绿阔叶林永久样地内23株母树种子的连续监测数据。结果表明:1)9年间共收集到栲成熟种子3万6572颗,种子产量为98.30颗/(m^(2)·a);种子产量的年际差异显著(P<0.05),其中2014、2018和2021年的产量明显大于其他年份;不同母树个体的种子产量年际差异显著(P<0.05),且明显大于种群尺度下的年际差异。2)栲种子平均质量为(0.50±0.19)g,平均变异系数为0.39,年际间差异较大,并与种子产量具有显著的负相关关系,种子高宽比在年际间较为稳定,且与种子产量没有明显的相关性,平均变异系数为0.04。栲种子质量和高宽比的变异主要来自于个体间,平均Gini系数分别为59.16%和69.77%。

不同覆盖物对丝栗栲种子发芽特性的影响

为了解不同覆盖物对丝栗栲种子发芽的影响,以丝栗栲种子为研究对象,采用无覆盖物、覆盖稻草、黄土、凋落物、松针的5种方式对丝栗栲种子进行处理,比较不同覆盖处理下丝栗栲种子的发芽特性。结果表明:不同覆盖物处理下,丝栗栲种子发芽特性存在差异,与无覆盖物处理相比,覆盖黄土虽使丝栗栲起始发芽时间与持续发芽时间减少的最短,分别减少4 d和2 d,但对丝栗栲种子发芽势与发芽指数影响均达显著水平(P<0.05),发芽势增大了0.08,发芽指数增大了0.35,而覆盖稻草处理下,丝栗栲发芽指数减少了0.04。相比其他覆盖物处理,覆盖黄土处理丝栗栲种子发芽特性表现出明显优势,其发芽率、发芽指数、发芽数与发芽势均为最大,发芽率增加了15.17%,发芽数增加了30粒。不同覆盖物处理对丝栗栲种子发芽特性产生明显影响,其中,覆盖黄土处理有利于丝栗栲种子发芽。

江西大岗山常绿阔叶林优势种丝栗栲和苦槠栲不同叶龄叶片光合特性研究

利用LI-6400便携式光合作用测量系统,研究了江西大岗山常绿阔叶林优势种丝栗栲和苦槠栲树冠中部不同叶龄叶片的光合生理特征。结果表明: ( 1 )丝栗栲叶片和苦槠栲叶片的净光合速率(Pn)、蒸腾速率(E)、气孔导度(Gs)、表观量子产量(AQY)、CO2 羧化效率(CCE)均表现为当年生叶片>1年生叶片>2年生叶片; (2)在相同叶龄条件下,丝栗栲叶片的净光合速率(Pn)、光补偿点(LCP)、表观量子产量(AQY)、气孔导度(Gs)、蒸腾速率(E)、CO2 羧化效率(CCE)、光能利用率(LUE)均显著高于苦槠栲叶片的相应值; (3)在相同叶龄条件下,丝栗栲叶片和苦槠栲叶片的水分利用率(WUE)没有显著差别; (4)2种植物叶片中的Chla/Chlb则表现为2年生叶片>1年生叶片>当年生叶片。

丝栗栲林生长与生产力的研究

在福建省邵武市洪墩采育场，调查丝栗栲林标地１０块，做平均木、树干解析木９株，杉木人工林标地２块，研究丝栗栲的生长与生产力，结果表明：丝栗栲林的胸径、树高及单株材积总生长量，均随年龄的增加而增加；胸径２０ａ前生长最快；树高１６ａ前生长最快；材积３６ａ时尚未有下降的趋势。胸径、树高平均生长量，随年龄增加而增加，当生长量达高峰后，则随年龄的增加而下降；胸径生长高峰，好立地１２ａ，中、劣立地１５ａ；树高生长高峰，好立地１０ａ，中立地８ａ，劣立地１２ａ；材积平均生长量，随年龄增加而增加，好、劣立地３６ａ时仍未下降，中立地３４ａ时生长量最大。胸径、树高连年生长量随年龄增加而下降；材积连年生长量，随年龄增加而增加，当生长量达高峰后，则随年龄增加而下降，生长高峰出现的年龄，好立地２８ａ，中立地２２ａ，劣立地２６ａ。在相似的立地条件下，丝栗栲林的蓄积量比杉木人工林低，但乔木层总生物量比杉木林高。

人为干扰对碧峰峡栲树次生林群落物种多样性及其优势种群生态位的影响

为进一步了解人为干扰对碧峰峡生态旅游区的生态环境及不同种群利用资源、占据生态空间的能力的影响,并为该区植物资源、大熊猫栖息地的保护及旅游可持续措施的制定提供依据,调查了人为干扰下碧峰峡栲树(Castanopsis fargesii)次生林物种多样性及其优势种群生态位的组成情况。结果表明:7200m2的样方中共记录到156个植物种,隶属于70科114属,其中乔木16科23属33种,灌木39科67属95种,草本38科42属47种;乔木层总体物种多样性水平在中度干扰下最低,在轻度及重度干扰下差异不大。灌木层总体物种多样性水平在中度干扰下最高,在轻度干扰下最低。而草本层物种多样性随着干扰强度的加深有明显降低趋势;随着人为干扰强度的增加,乔木层中优势种栲树的生态位宽度均为最大,与其他树种生态位重叠值在中度干扰下有所降低,枹栎(Quercus serrata)的生态位宽度会变小,山茶科(Theaceae)植物的生态位变宽,同时其生态位重叠值增大;在灌木层中,重度干扰下,菝葜(Smilax china)生态位宽度减小,栲树幼苗的生态适应范围也骤减,其他大多数物种在中度干扰下,生态位宽度最低;在草本层中,蕨类植物及皱叶狗尾草(Setaria plicata)在重度干扰下生态位宽度及重叠值均增高,其适应范围变广,种间竞争加剧。综合分析表明,群落各层次物种多样性水平对人为干扰的响应各不相同,其中人为干扰对灌木及草本层物种多样性影响最大。同时人为干扰会改变群落物种组成及种间原有的关系,特别是中度干扰会使群落间优势种地位增强,种间竞争关系加剧,导致其原有生境被破坏,不利于群落发展。因此强化景区保护及合理经营迫在眉睫。

福建大田栲树次生林优势种群结构与动态

在福建大田栲树(CastanopsisfargesiiFranch.)次生林内,应用相邻格子法设置3200m2样地,进行优势种群结构和空间格局的研究。结果表明,栲树种群、罗浮栲(C.fabriHance)种群、樟树〔Cinnamomumcamphora(Linn.)Presl〕种群结构呈金字塔型,栲树种群和罗浮栲种群从Ⅰ、Ⅱ级幼苗到Ⅲ级幼苗发育过程中出现死亡高峰;3个优势种群从Ⅲ级幼苗向第4立木级的生长过程中,死亡率也很高。栲树、罗浮栲和樟树种群在不同发育阶段空间分布格局差别较大,栲树种群在幼树阶段为集群分布,中树及大树阶段为随机分布;罗浮栲种群在幼树阶段呈集群分布、中树阶段呈均匀分布、大树阶段呈随机分布;樟树种群在幼树及大树阶段呈均匀分布,中树阶段为随机分布。不同区组规模对种群空间分布格局产生影响。

丝栗栲种群生命过程及谱分析

以种群生命表及生存分析理论为基础 ,编制丝栗栲种群静态生命表 ,绘制存活曲线、死亡率曲线、亏损度曲线、死亡密度函数曲线、积累死亡函数曲线和危险率函数曲线 ,分析种群生命过程 .结果表明 ,丝栗栲有 2个死亡高峰 ,存活曲线趋于Deevey II型 .并应用谱分析方法研究丝栗栲种群动态 ,结果表明 ,在丝栗栲种群自然更新过程中存在着明显的周期性 .图 3表 4参

中亚热带丝栗栲次生林群落高度级结构分析

以高度级为参考坐标 ,应用衡量优势种群及群落结构动态的失稳率、群落垂直空间的分享度、α -多样性及群落高度级梯度β -多样性等指标对中亚热带丝栗栲次生林群落高度级结构特征及其动态进行分析评价 .结果表明 :丝栗栲群落及其优势种群个体数、群落物种数和种对级的分享度随高度级增加都呈下降趋势 ;各高度级物种数和个体数呈明显的正相关关系 ;级间失稳率显示 ,群落在第 2、3、6、7高度级呈增长趋势 ,第 4、5高度级呈衰退趋势 ,群落整体具有增长性结构 ;群落随高度级形成丰富度指数 (dMa)、Shannon -Wiener指数 (H)逐渐降低 ,均匀度指数 (J)先增后减的变化趋势 ;随高度级梯度的增加 ,群落相邻高度级间Whittaker指数 (βw)呈上升趋势 ,而Morisita -Horn指数 (CMH)呈不规则地跳跃式变化 ,表现了共有种在群落不同高度级的数量差异 .图 3表 2参

江西大岗山常绿阔叶林优势种丝栗栲和苦槠栲光合日动态特征研究

利用美国LI-COR公司的LI-6400便携式光合作用测量系统,研究了江西省亚热带常绿阔叶林主要优势种丝栗栲和苦槠栲的光合日动态特征。结果表明,丝栗栲和苦槠栲叶片的净光合速率(Pn)日变化均呈现“双峰型”,有明显的光合“午休”现象。两者的净光合速率均在上午11:00达到最大值,分别为11.84μmol/(m2.s)和9.54μmol/(m2.s);两者的净光合速率均在15:00达到次高值,分别为9.09μmol/(m2.s)和5.13μmol/(m2.s)。造成丝栗栲叶片和苦槠栲叶片光合“午休”的主要原因为气孔限制。在一天中,丝栗栲叶片的净光合速率(Pn)均高于苦槠栲叶片的净光合速率(Pn)。