林地土壤及其真菌对毛红椿种子发芽及幼苗保存的影响

[目的]通过不同群落毛红椿天然林林地土壤及其真菌对种子萌发和幼苗存活影响的研究,探讨影响毛红椿天然更新的障碍因素。[方法]在江西九连山国家级自然保护区内的3个毛红椿天然优势群落中,分别取距离毛红椿母树3个不同距离(2.5、5.0、7.5 m)处的根区土壤和远离毛红椿母树(25 m以外)的非根区土壤,以非林地土为对照开展室内模拟播种和以根区土壤真菌的水或根系分泌物悬液对毛红椿幼苗进行灌根接种,观察种子萌发、幼苗存活和幼苗感病情况。[结果]各群落土壤中种子发芽均呈先上升后下降规律,且基本在第8 10天达到高峰;林地土与非林地土种子发芽率差异不显著,但林地根区土幼苗的存活率极显著低于非林地土和林地非根区土;距母树3个不同距离根区土的幼苗存活率差异不显著。灌根接种不同处理间幼苗存活率差异极显著,具体表现为接种RS2、RS5根区真菌的幼苗感病率显著高于根系分泌物及无菌水空白对照,且RS2真菌的根系分泌物悬浮液幼苗感病率显著高于其无菌水悬浮液。[结论]毛红椿种子萌发不受土壤环境的影响,但幼苗建成受根区范围内土壤的影响,根系分泌物和致病菌的互作显著降低幼苗保存率。由此推断,毛红椿根区土壤内存在幼苗的潜在致病菌及根系分泌物可增强其致病性。     

不同育苗基质的团花根际微生物群落功能多样性特征

利用Biolog-ECO技术对不同育苗基质培育下的团花根际微生物群落功能多样性进行研究。结果表明:不同育苗基质的团花根际微生物群落功能多样性有显著差异,13#甘蔗渣堆肥用作团花育苗基质能显著增强微生物对碳源的利用,13#育苗基质培育的团花根际微生物总体表现较高的活性,并且根际微生物利用碳源的类型以糖类、羧酸类和氨基酸类化合物相对较多,如:D-半乳糖酸γ--内脂、D-甘露醇、D-纤维二糖、衣康酸、L-精氨酸、L-天门冬酰胺和L-丝氨酸。     

植被和凋落物对水杉天然幼苗萌发的影响

为查明水杉天然更新的关键障碍因素,探索促进水杉天然更新的有效途径,在野外原生境中选择5株水杉母树作为研究对象,以水杉母树为中心设置样圆,在样圆内采用不同林下处理方式(群落阻隔、林下活地被物阻隔、凋落物阻隔和无阻隔)进行分区试验,研究植被和凋落物对水杉天然更新的影响。结果表明：不同林下处理方式对水杉幼苗更新密度、存活率、苗高、地径、根长、叶片数量、叶面积、地上生物量和地下生物量有极显著影响(P<0.01);幼苗萌发生长指标均在无阻隔区达到最大值,再由高到低依次是凋落物阻隔区、林下活地被物阻隔区、群落阻隔区。水杉林下活地被物、凋落物和群落环境均是造成水杉天然更新困难的障碍因素,对水杉种子萌发和幼苗生长抑制程度的排序为：群落环境>林下活地被物>凋落物。水杉幼苗苗高的生长动态变化符合S型生长曲线(R²≥0.893), 4种处理方式的水杉幼苗更新密度均呈倒“V”形分布。无阻隔处理显著促进了水杉幼苗的天然更新,其存活率、苗高、地径、根长、叶片数量、叶面积、生长速率及生物量等指标均最高;今后在水杉种群保护和管理中,应适当清除林下活地被物和凋落物,为水杉种子萌发...     

森林天然更新障碍机制研究进展

在搜集国内外大量文献资料的基础上,综述种子缺乏,动物取食与侵害,植物化感作用,微生物致病,光照、温度、湿度、水分等生态因子异常,林下活地被物与枯枝落叶的物理阻隔,自然和人为干扰作用以及群落结构特征对森林天然更新的障碍机制,提出现有研究存在的问题和发展思路。     

五氯酚胁迫对杨树生长及根际微生物群落的响应特征

采用温室盆栽试验方法研究五氯酚污染胁迫对4个杨树品系生长及根际微生物特征的影响.结果表明:在不同浓度五氯酚污染胁迫下,供试杨树的株高和地径差异显著;氯仿熏蒸测试结果显示,杨树根际土壤微生物量碳含量随着五氯酚污染浓度增加而下降,表明五氯酚对土壤微生物活性产生毒害作用;Biolog测定结果显示:五氯酚污染处理的杨树根际土壤微生物平均每孔颜色变化率值始终大于对照,主成分分析结果也显示五氯酚污染处理对杨树根际土壤微生物的碳源利用造成显著影响,初步判断一定浓度范围的五氯酚与根际分泌物的联合作用有利于增强根际土壤微域内特定微生物群落的生理代谢活性,从而增加其碳源利用程度.结果表明:杨树根际土壤微生物群落的Shannon指数,Simpson指数和McIntosh指数均高于对照,微生物群落的丰富度、均匀度和优势度得到增强,并且五氯酚对土壤微生物的刺激作用随浓度的增加而增强.     

迷人杜鹃群落天然更新障碍的化感研究

为明确影响野生迷人杜鹃群落天然更新的化学因子,探明迷人杜鹃各土壤层中的化感物质状况。通过发芽试验比较了不同土壤层的水浸提液处理的迷人杜鹃种子的萌发状况,采用衍生化气质联用法(GC-MS)分析鉴定不同层次土壤中的化感物质。实验结果表明:迷人杜鹃不同浸提液对种子萌发的化感效应差异显著,其中枯枝落叶层对种子萌发的抑制作用最强,显著抑制种子萌发;枯枝落叶层、腐殖质层和土壤层中所含的化感物质总量表现为枯枝落叶层腐殖质层土壤层,各土壤层中的化感物质均以棕榈酸含量最高。     

濒危植物蒙古扁桃种子雨和土壤种子库特征

种子作为木本植物或灌木树种的主体,在群落更新中起着重要作用.充足的良好种源是物种天然更新成功所必须具备的条件之一,而一个物种的种源多少是由种子生产、种子雨密度、种子库动态决定( Simpson,1989).种子雨是种子靠自身的重力和借助外界力量(风力等)散布到地表的过程,是群落更新发展的关键环节,也是植物生命史动态过程不可缺少的环节(Harper,1997;于顺利等,2007).土壤种子库是指存在于土壤上层凋落物和土壤中的全部存活种子总和( Simpson,1989),是影响植物群落天然更新的能力和方向的关键(Moles et al.,1999;杨跃军等,2001).种子雨和土壤种子库反映种子的扩散及空间分布状况,决定着个体、种群、群落的空间格局(Thiede et al.,1996;Willson,1993),在植被生态恢复中起决定性作用(Vander,1978;Streng et al.,1989;Shibata et al,1995).     

萌芽更新对桉树根际土壤微生物群落功能多样性的影响

本文以桉树新造林、一代萌芽更新林、二代萌芽更新林根际土壤微生物为研究对象,采用Biolog方法测定了萌芽更新对桉树根际土壤微生物群落功能多样性的影响。结果表明：随着培养时间的延长,各样点土壤微生物利用碳源的能力呈上升趋势,土壤微生物碳源平均颜色变化率排序为一代萌芽林〉二代萌芽林〉新造林;一代、二代萌芽林和新造林根际土壤中微生物群落具有明显的分异,起分异作用的主要碳源分别为羧酸类物质、多聚物类和氨基酸类;不同萌芽代数根际土壤中被利用碳源的丰富度和多样性指数之间的差异不显著。     

黄土高原不同树龄刺槐丛枝菌根与根际微生物的群落多样性

采用BIOLOG检测法,研究丛枝菌根与黄土高原不同树龄刺槐人工林及次生林根际微生物群落多样性的关系.结果表明:8、15、23和30年刺槐人工林随着树龄的增加,菌根侵染率先增加后降低,微生物活性(AWCD值)增大,碳源代谢丰富度指数(S)和Shannon指数(H)逐渐增加,23年达到峰值后趋于稳定,并逐渐降低,不同林地菌根侵染率与根瘤数呈显著正相关(Y=414.82 x-188.73,r=0.927,P＜0.05).主成分分析表明:刺槐人工林根际微生物群落结构与功能随着树龄的增加存在时间上的连续性,次生林优于相同树龄人工林,在碳源利用上表现为与树龄更长的人工林相近.菌根侵染率与根瘤数、细菌量、丰富度指数(S)和Shannon指数(H)的相关性分析表明:丛枝菌根对刺槐根际微生物群落的稳定和功能多样性的增加具有促进作用,在造林年限上表现为对较短树龄刺槐林根际微生物群落影响较大,在造林措施上对刺槐次生林微生物群落多样性的作用优于人工林.     

沙地樟子松林天然更新研究进展

沙地樟子松是我国北方地区广泛引种的主要固沙造林树种,但在引种地只有少数地区能够完成自然更新过程。本文从沙地樟子松落种特征、土壤种子库、种子扩散、种子萌发、更新苗特征、天然更新类型以及影响天然更新因素等方面综述了沙地樟子松天然更新研究现状,并探讨其天然更新的关键影响因素,同时提出了研究展望。     

动物取食和扩散森林植物种实研究进展

动物取食扩散森林植物种实作为森林生态系统中植物和动物联系的-个重要方面, 不仅是联系母株与其子代幼苗的重要桥梁, 也是植物生活史中的-个重要阶段。文中综述了近年来关于动物取食森林植物种实及其与这些植物种子散布、萌发、幼苗生长和种群扩展等方面关系的研究成果。动物在取食和破坏森林植物种实的同时也将这些植物的种子扩散到-个新的生境斑块, 其消化道机械的或化学的作用提高了这些森林植物的种子萌发率和萌发进程, 促进了其早期定居和种群扩大。动物对森林植物的这种作用具有长期性, 形成特定动植物间或多物种间的协同进化。近年来, 森林生态系统受到了严重的干扰和破坏, 可能会因为干扰了森林植物种实的动物散布者而影响森林植物种群的扩展。     

呼伦贝尔沙地樟子松天然林自然落种特征研究

研究了呼伦贝尔沙地樟子松天然林自然落种及其种子萌发特征,结果表明:丰年期落种器共接到99粒种子,且集中分布在母树的正东、东北侧,欠年期则接到落种42粒且集中分布在正东、东南侧。丰年期不同方位、不同落种距离接到的种子平均发芽率为54.5%,欠年期为28.6%。樟子松林缘落种的传播距离范围可以达到25 m,并且在林缘外5 m范围内种子数量最多,林缘外5～20 m范围平均发芽率为60.9%。樟子松单株树木下土壤种子库中种子数量在4 m处最高,并且随着距树干距离的增加种子数量也随之降低,种子总数由2 m处样方的16粒降低到10 m处样方的7粒,降低百分率达129%。     

墨西哥丁香引种、繁殖试验初报

对热带固氮速生树种墨西哥丁香进行引种、繁殖及早期试种的试验。结果表明，清水浸种处理的种子发芽率较高，达76.5%。以无菌种子为外植体材料，在适宜的培养基上培养时不定芽的增殖可达1.5倍以上。扦插育苗以木栓化枝条作插穗的成活率最高，可达98％。该树种生长迅速，抗逆性强，砍伐后萌芽率高，定植2年已有植株开花。初步试验结果认为该树种有希望成为一种适宜在华南地区发展的水土保持林树种或混交林伴生树种。     

Ecophysiological characteristics of the seed of the tropical forest pioneer Urera caracasana (Urticaceae)

Urera caracasana (Jacq.) Griseb is a small, fast-growing evergreen pioneer tree which colonizes openings in the tropical rain forest of 'Los Tuxtlas', Veracruz, Mèxico. Annual seed production by 10 trees was estimated to range from 0.4 x 10(5) to 1.6 x 10(6) seeds per tree. Fifteen species of resident and migratory birds were observed to visit the plants and disperse the seeds. Most seeds imbibed in petri dishes placed on the forest floor beneath a small opening in the canopy, where the red/far-red ratio of the light was around 1.0, germinated within 2 weeks. Germination beneath the forest canopy, where the red/far-red ratio of the light was approximately 0.2, was much slower and did not exceed 40%. A minimum of 4 h daily exposure to unfiltered natural light was required for rapid germination in the forest. In the laboratory rapid germination at 25 degrees C required a minimum of 4 h white light. However, if temperature during the light period was 35 degrees C, 30 min exposure to white light daily was sufficient to induce germination. Seeds that failed to germinate when imbibed for 60-360 days in petri dishes placed on the forest floor beneath the forest canopy, germinated rapidly in the laboratory when held at 25 degrees C and exposed daily to 12 h white or red light. Seeds imbibed for 120 days or more beneath the forest canopy were also induced to germinate by 12 h daily exposure to far-red light when this was combined with a 35/25 degrees C day/night temperature regime. Seeds buried in vermiculite-filled nylon mesh bags disappeared rapidly with few remaining after 2 months. Seeds that survived remained viable and germinated when incubated in petri dishes at 25 degrees C. Initially, buried seeds required light for germination. However, after 17 months' burial, seeds germinated in darkness when transferred to the laboratory and incubated on agar at 25 degrees C.     

Effects of seed traits on the success of direct seeding for restoring southern Thailand’s lowland evergreen forest ecosystem

The success of direct seeding, as a low-cost approach to forest restoration, varies with tree species and seed characteristics. A system to predict which tree species are likely to be suitable for direct seeding would therefore be useful for improving forest restoration projects. Therefore, this study aimed to determine the effects of seed traits on the success of direct seeding to restore tropical forest in southern Thailand. Seeds of 19 indigenous lowland tropical forest tree species were collected, from both the east and west sides of the Thailand peninsular and the following parameters measured: seed size, shape, coat thickness and moisture content. Field trials were established to determine seed germination rates and to calculate a “direct seeding suitability score” for each species, which combined seedling establishment and growth rates. Seed size, shape and moisture content were associated with germination percentage. Species with higher seedling survival tended to have large or intermediate-sized seeds, round or oval seeds and seeds with low or medium moisture content. Only seed coat thickness was significantly correlated with the suitability score (r = 0.65, p < 0.01). Seed coat thickness >0.4 mm coincided with higher rank suitability score. These conditions successfully predicted the success or failure of direct seeding for 15 out of 19 species tested. Eight tree species are recommended as suitable for restoring lowland evergreen forest ecosystems in southern Thailand, by direct seeding.     

林木种子的发芽技术

依据林木种子的生理、形态特征、解剖结构 ,在通常采用的 6种发芽方法中 ,选择适合于种子特征 (形态、生理 )的发芽方法 ,经 10 0个树种、 30 0 0多个种批的发芽验证 ,总结了 4类种子的发芽要点、技术条件 ,给出了 10 0个树种发芽率的最高值 ,为绿化造林、苗木培育的种子发芽提供参考依据     

植物的化感作用及其在林业经营中的运用

在自然界中植物的化感作用广泛地存在着,它与植物对光、水分、养分和空间的竞争一起构成植物间以及与其他生物间的相互作用,它影响着植物的分布、群落的形成和演替、种子的保存和萌芽、真菌孢子的萌发、氮素的循环等,在林业经营中有着广阔的运用前景。在对化感物质和化感作用的基本原理以及生物间存在的化感作用作综述性介绍的基础上,重点论述了化感作用对森林生态系统的影响,及其在森林更新、混交林培育和开发新型生物农药中的潜在价值,以期进一步推进对化感作用机制及应用的研究。     

Factors influencing germination and establishment of Eucalyptus pauciflora near the alpine tree line

Factors affecting seed germination, seedling establishment and growth to reproductive maturity in Eucalyptus pauciflora Sieb. ex Spreng. at the tree line in southeastern Australia were investigated. Timing of germination was determined principally by temperature but could be strongly modified by soil water. Mortality of germinants was heaviest during the first growing season (dependent on soil water) and the first winter (dependent on the depth and duration of snow cover). Neither plant nor soil treatments with insecticide or fungicide had an overriding or consistent effect on germination or seedling establishment. The probability of reaching the sapling stage was greater for planted seedlings than for plants germinated on site, indicating the dependence of survival on accumulated reserves. There was no clear indication of a general decrease in survival with increasing altitude, because of an interplay between elevation and site factors including competing vegetation, snow depth and period of snow cover. Five-year-old saplings planted up to 200 m above the tree line produced reproductive structures and viable seed between the ages of 13 and 18 years. The relevance of the results to an understanding of the location of the present tree line is discussed.     

Novel dry forests in southwestern Puerto Rico

We report results of new research on (1) community composition of novel subtropical dry forests developing on abandoned pastures and agricultural fields in both private and protected public lands and (2) seed germination and growth rates of plantings of native tree species on degraded soils. We found that novel dry forests were dominated by introduced species, which accounted for 59 percent of the Importance Value (IV) of stands. These forests had high species dominance, with the most dominant species averaging 51 percent of the IV but reaching values as high as 92 percent. The floristic similarity between novel and mature native forests was low (5.6 percent) compared with the similarity among novel forest stands (26 percent). Collectively, the emerging novel forests had relatively high species richness (39 species/1.2 ha). After 45-60 years of growth and development, novel forests lagged mature native forests in basal area, tree density, and species richness, and lagged stands of similar age and past land use inside a protected area. Novel forest stands inside the protected Guánica Forest had higher species richness than those located outside in private lands. Most regeneration was from seed (67 percent of the new stems were single stems). The results from the germination and planting experiment show that seeds of 17 of 21 native tree species germinated in the laboratory and grew successfully in abandoned pastures when planted and watered for a period of 13 months. Our research shows that after the initial invasion and dominance of introduced species on degraded sites, the stands diversify with native species thus evolving towards new forest types with novel species combinations.     

杜仲种子内生微生物群落组成及生态功能分析

目的 揭示杜仲种子内的微生物群落组成和多样性,丰富杜仲相关微生物资源。 方法 本研究采用传统培养法和高通量测序技术对杜仲种子内生微生物群落组成和多样性进行分析,同时基于FAPROTAX 和FUNGuild数据库对其进行功能注释。 结果 从杜仲种子中共分离获得真菌40株（3门11属）,优势属为曲霉属（Aspergillus）（30%）;细菌142株（1门6属）,其中,土壤芽孢杆菌属（Solibacillus）（47.18%）为主要优势属。高通量测序获得141个真菌OTUs,隶属于6门101属;442个细菌OTUs,隶属于24门313属。在属水平,种子优势真菌属为Apiotrichum（31.28%）和德巴利氏酵母属（Debaryomyces）（26.07%）;优势细菌属主要为假单胞菌属（Pseudomonas）（16.66%）和乳杆菌属（Lactobacillus）（9.68%）。功能注释结果显示：真菌以降解有机物、促进宿主植物生长、促进宿主对土壤养分的吸收、改善土壤环境微生物群落结构以及致病菌群为主;细菌以化能异氧、有氧化能异养以及具有发酵和固氮作用的菌群为主。 结论 杜仲种子内携带多种有益功能菌和潜在致病菌,这些微生物对植物的生长发育具有重要影响。同时本研究还分离到多株有益功能菌,这将为后续人为调控种子微生物组以增强植物健康提供微生物资源。