[目的]研究重庆金佛山3种喀斯特森林群落(常绿落叶阔叶混交林、落叶阔叶林和常绿阔叶林)木本植物种子雨和土壤种子库的组成、动态、空间分布格局及幼苗萌发情况,揭示喀斯特森林的更新潜力与发展方向,为喀斯特森林管理提供理论依据.[方法]在每种林型中随机设置9个种子雨收集器,从种子下落初始到结束,每15天收集1次,共收集8次.同时在每种林型中随机挖取6个土壤种子库样方,分枯落物层、0～2 cm土层和2～5 cm土层取样,对种子雨、种子库所收种子进行分类鉴别,并分别统计完整、虫蛀、残缺和霉腐4类种子的数量,应用氯化三苯四氮唑(TTC)染色法对所有完整种子进行活性鉴定.采用样方法调查幼苗种类和数量.[结果]3种林型种子雨的下落时间和高峰期时间基本一致;常绿阔叶林种子雨强度最大(1453颗·m-2),其次为落叶阔叶林(486.11颗·m-2),常绿落叶阔叶混交林(152.22颗·m-2)最低,林型间种子雨强度差异显著(P<0.05);3种林型种子雨中活性种子占比(活性种子数量占完整种子数量的比例)差异显著(P<0.05),表现为常绿阔叶林(55.41％)>常绿落叶阔叶混交林(47.41％)>落叶阔叶林(44.44％);种子雨中的虫蛀、残缺和霉腐种子占种子雨总量的比例均表现为常绿落叶阔叶混交林>常绿阔叶林>落叶阔叶林;在不同时期(8月和12月),土壤种子库总储量差异显著(P<0.05),均表现为常绿阔叶林>常绿落叶阔叶混交林>落叶阔叶林;在种子雨下落前(8月),3种林型的种子均集中分布在0～2 cm土层,其次是2～5 cm土层,枯落物层最少,但在种子雨下落后(12月),常绿落叶阔叶混交林和常绿阔叶林表现为0～2 cm土层>枯落物层>2～5 cm土层,落叶阔叶林表现为枯落物层>0～2 cm土层>2～5 cm土层;3种林型中幼苗数量差异显著,落叶阔叶林最多,其次是常绿落叶阔叶混交林,最后是常绿阔叶林(P<0.05);3种林型的种子雨、土壤种子库及幼苗间的物种相似性均较低,种子雨和土壤种子库的物种组成相似性系数在常绿阔叶林中最高,在落叶阔叶林中最低,种子雨和幼苗的物种组成相似性系数在落叶阔叶林中最高,在常绿阔叶林中最低,土壤种子库和幼苗的物种组成相似性系数在3种林型均很低.[结论]金佛山喀斯特森林木本植物的种子雨强度、土壤种子库储量较大,且活性种子占比较高,该地区森林群落有较强更新基础与潜力.但种子雨、土壤种子库及幼苗数量在不同林型中均差异显著.木本植物幼苗在落叶阔叶林下最多,而在种源最充足的常绿阔叶林下最少,说明郁闭度高、土壤含水量低的生境不利于幼苗更新.管理喀斯特森林时,需重视林型差异对幼苗更新的影响,合理规划林分结构,改善林下光照、枯落物和土壤条件,降低种子损耗,为木本植物种子萌发、幼苗建立提供良好条件,从而促进喀斯特森林更新与恢复.

[目的]探究紫耳箭竹种群(Fargesia decurvata J.L.Lu)在不同林型下的生长和繁殖特征,探讨长寿命一次性开花结实的竹类克隆繁殖和有性繁殖的权衡特性.[方法]以金佛山国家级自然保护区3个典型林型:落叶阔叶林(De)、常绿落叶阔叶混交林(De+Ev)和常绿阔叶林(Ev)下的灌木层优势种紫耳箭竹为试验材料,研究不同林型下紫耳箭竹种群在营养生长期和果期的形态可塑性、生物量积累与分配特性以及繁殖特征.[结果]表明:(1)相较于营养生长期,果期紫耳箭竹单株叶片数在De和De+Ev中显著减少,在Ev中没有显著变化;隔离者长度、隔离者节间数、隔离者直径、隔离者节间均长在De和De+Ev中均降低,在Ev中均增加;果期De中的紫耳箭竹单株小穗数高于De+Ev和Ev.(2)从营养生长期向果期过渡过程中,De和De+Ev中的紫耳箭竹分株叶片生物量和分配比例急剧下降,其余构件的生物量和分配比例无明显变化;Ev中各构件生物量除叶片外均显著增加,分配比例则在枝中显著增加,在叶片和根中显著降低;秆和枝作为支撑器官在3个林型中均占据很大的生物量分配.(3)在营养生长期,3个林型中的紫耳箭竹均产生竹笋进行克隆生长,且De+Ev中的竹笋数显著高于Ev,Ev的单位面积竹苗数显著低于其余2种林型,秆组织密度显著低于果期.在果期均不产生竹笋只产生种子,且单株结实率和生殖分配都很低.[结论]紫耳箭竹种群的形态特征、生物量积累与分配特性在不同生活史阶段不同,且在不同林型间也存在差异;克隆生长与有性繁殖间存在明显的权衡,随着有性繁殖的进行,克隆生长能力随之变弱并逐渐消失.

The formation causes of sparse vegetation under Acacia mearnsii plantation were studied from the perspective of plant allelopathy. The interference effects of water extract with different concentrations(1, 5, 10, 15 times) from Acacia mearnsii leaves on seed germination and seedling growth of four receptor plants was assayed through indoor biological simulation experiments, the four receptor plants are Ageratina adenophora, Trifolium repens, Eucalyptus robusta and Eucalyptus camaldulensis, respectively. The results show that different concentrations( 1, 5, 10, 15 times) of water extract from Acacia mearnsii leaves all had inhibitory effects on seed germination and seedling growth of the four receptor plants, the synthesized effect index(S EI) ranged from-0.246 to-0.002; there existed an obvious regularity of inhibitory effects to Ageratina adenophora and Trifolium repens, and the inhibitory effect reduced with the increase of water extract dilution ratio, the S EI of inhibitory effect on Ageratina adenophora treated with 1 times was-0.246; however, there was no regularity in inhibitory effect on Eucalyptus robusta and Eucalyptus camaldulensis, the inhibitory effects of 1 times and 10 times were more obvious than the other two groups, the S EI of inhibitory effect on Eucalyptus robusta treated with 5 times was-0.002. The possible cause of sparse vegetation under Acacia mearnsii plantation is allelopathy of Acacia mearnsii hydrotrope.

Ageratina adenophora is a worldwide weed which leads to serious harm in Southwest China.It has been an urgent demand to be controlled.Previous studies have shown that chemical compositions from Eucalyputs spp.have various biological activities and broad application prospects.To explore the effects of five important chemical compositions from Eucalyptus spp.on seed germination and seeding growth of A.adenophora,the effects of five main chemical compositions from Eucalyputs spp.as 1,8-Cineole,α-Pinene,α-Terpineol,Limonene and Borneo on germination and growth of A.adenophora were studied by using indoor biological simulation experiment in this study.The results showed that seed germination and seeding growth of A.adenophora were inhibited comprehensively by the five chemical compositions at 10,50,100 mg/L concentration,and the synthetical allelopathic effect index ranged from-0.04 to-0.96.Among those,the inhibitory effects of α-Terpineol solution at different concentration were the most significant,which led receptor seeds to extremely low germination rate,seedling radicles and hypocotyls to cease growing and even die.Absolute value of comprehensive index of α-Terpineol reached over 0.95.The inhibitory actions of 1,8-Cineole,α-Pinene and Borneol on seed germination and seedling growth of A.adenophora enhanced with the concentration increased.The inhibitory effects of Limonene were weak at 50 mg/L concentration and strong at 10 mg/L and 100 mg/L concentration.The results above indicated that the five chemical compositions from Eucalyptus spp.inhibited seed germination and seeding growth of A.adenophora.The studies are expected to provide a new solution to prevention and control of A.adenophora and also a new development approach of plant-derived pesticides.

By using the Bioassay method,this artilce carries on the water extract analysis of mature leaves and leaf litter of Eucalyptus globulus on the seed germination of Eupatorium adenophorum,in order to provide a new way for the biological control of E.adenophorum.The experimental results show that:the mature leaves and leaf litter concentrations of water extract on the seed germination parameters all show inhibiting effects,and the inhibiting effects increase with the rise of the concentration,and when the concentration is 6.30g /L,all the differences reach a very significant level ;through the comprehensive evaluation of the allelopathic potential donor,the absolute value of the combined effect index of two water extracts of Eucalyptus globulus leaves on Eupatorium is about 40%,and the mature leaves are slightly larger than the leaf litter.