六盘山区辽东栎的实生苗更新及其影响因子

研究了六盘山区辽东栎(Quercus liaotungensis)灌丛的种子产量、土壤种子库组成、湿沙和风干贮藏对种子寿命的影响以及动物取食子叶对种子萌发和幼苗建立的影响。结果表明, 辽东栎灌丛种子的完好率为27.51%, 被动物取食或搬运种子的比例(41.51%)显著高于其他类型种子(p < 0.01); 辽东栎次生林土壤种子库中萌发和虫蛀种子分别占35.16%和38.29%, 完好种子仅占13.65%, 捕食动物主要通过贮藏或搬运而影响土壤种子库中的种子密度。湿沙贮藏60天的辽东栎种子自动萌发率高达96.67%, 短期贮藏可加快种子的萌发进程, 提高萌发率和萌发指数, 但随着贮藏时间的延长, 种子萌发进程延迟, 萌发率、萌发指数和活力指数均不同程度地降低。排除动物取食处理的幼苗在林窗和林下生境的存活率分别为80%和83%, 而不排除动物取食幼苗在2种生境中分别仅有25%和31%能够存活, 表明子叶在幼苗建立中具有重要作用。林窗中幼苗子叶的动物取食率(85.00%)高于林下(71.00%), 子叶留存的幼苗在林窗中的存活率(6.00%)低于林下(15.50%), 而子叶被取食幼苗的存活率在两种环境中基本相等(分别为18.50%和18.00%)。     

动物与植物种子更新的关系Ⅱ．动物对种子的捕食、扩散、贮藏及与幼苗建成的关系

植物的繁殖体总是面临来自各类生物（如昆虫、脊椎动物、真菌）的捕食风险。因动物捕食引起的种子死亡率影响植物的适合度、种群动态、群落结构和物种多样性的保持。种子被捕食的时间和强度成为植物生活史中发芽速度、地下种子库等特征的主要选择压力,而种子大小、生境类型等因素也影响动物对植物种子的捕食。捕食者饱和现象被认为是植物和种子捕食者之间的高度协同进化作用的结果,是限制动物破坏种子、提高被扩散种子存活率的一种选择压力。大部分群落中的大多数植物种子被动物扩散。种子扩散影响种子密度、种子被捕食率、病原体攻击率、种子与母树的距离、种子到达的生境类型以及建成的植株将与何种植物竞争,从而影响种子和幼苗的存活,最终影响母树及后代植物的适合度。种子被动物扩散后的分布一般遵循负指数分布曲线,大多数种子并没有扩散到离母树很远的地方。捕食风险、生境类型、植被盖度均影响动物对种子的扩散。植物结实的季节和果实损耗的过程也体现了其对扩散机会的适应。许多动物有贮藏植物种子的行为。动物贮藏植物繁殖体的行为,一方面调节食物的时空分布,提高了贮食动物在食物缺乏期的生存概率;另一方面也为种子萌发提供了适宜条件,促进了植物的扩散。于是,植物与贮食动物形成了一种协同进化关系,这种关系可能是自然界互惠关系（mutualism)的一种。影响幼苗存活和建成的因子包括种子贮蒇点的微生境、湿度、坡向、坡度、林冠盖度等。许多果食性动物吃掉果肉后,再将完好的种子反刍或排泄出来。种子经动物消化道处理后,发芽率常有所提高。     

食果鸟类在红豆杉天然种群形成中的作用

2005年10月初至2006年2月,在南京中山植物园研究了红豆杉(Taxus chinensis)天然更新种群的分布格局,野外定点观察了鸟类对红豆杉种子的取食行为,记录了红豆杉落果的命运,分析了食果鸟类在红豆杉种群形成中的作用。结果表明:红豆杉天然更新种群集中分布于距母树群10m以外面积约0.5hm2的山坡上,全部红豆杉幼苗、幼树共213株,主要分布在中下坡;幼苗和幼树的空间水平格局符合聚集分布特征。"果实"成熟后,一部分被鸟类直接在树上取食,一部分掉落母树下地面。经过对结实母树的定点、连续观察,记录到4种鸟类取食红豆杉"果实",其中红嘴蓝鹊(Urocissa erythrorhyncha)和白头鹎(Pyc-nonotus sinensis)为主要的取食者和传播者。食果鸟类整吞"果实",消化果肉(假种皮)后,种子经消化道随粪便排出,以此过程传播种子。在取食完红豆杉"果实"后,食果鸟类多飞向坡上。坡上排水良好,有适量的荫蔽,生境适宜红豆杉种子萌发和幼苗的成长。因此,食果鸟类将种子传播至适宜萌发和生长的环境中,对该红豆杉种群的天然更新起主要作用。同时,鸟类传播对于红豆杉种群扩散、占据新的生境也有着特殊的意义。     

黄檗的更新特点及食果实鸟类对其种子的传播

在帽儿山实验林场和哈尔滨实验林场 ,黄檗母树下没有幼苗分布 ,不能进行天然更新 ,需要靠食果实鸟类等将果实和种子传播至远离母树的其他林下。捕食黄檗果实的食果实鸟类有 9种。其中 6种是食果肉鸟类 ,吞入果实后 ,消化果肉 ,而种子完整地随粪便排出而得以传播。其余 3种是食种子鸟类 ,没有传播作用。果实在鸟类消化道内的滞留时间达 2 0～ 30min ,具有很长的潜在传播距离。将鸟类消化后的种子与完整果实和人为去果肉种子进行萌发对比实验 ,消化后种子的累计萌发率与其余二者之间均没有显著性差异 ,说明食果实鸟类的消化 (道 )过程对种子萌发没有明显影响 ,同时证明果肉对种子萌发率没有显著影响 ,果肉中不含萌发抑制物质。黄檗提供多种鸟类以食物 ,而鸟类也同时以多种肉质果植物为食物。因此食果实鸟类和肉质果植物 (包括黄檗 )之间形成了松散的互利共生关系     

鼠类对山杏种子存活和萌发的影响

山杏（Prunus armeniaca)是广布于北京山区阳坡的矮林或灌丛,易生存在土壤贫脊、干旱、或严重退化的山坡、裸地,对于保护生态环境,减少水土流失及促进山区经济发展均具有重要作用。有关鼠类在山杏更新中作用的研究较少,本研究主要是确定影响山杏更新的鼠类种类、鼠类对山杏种子的取食压力、人工埋藏种子及植被因素对种子存活和萌发的影响。于1997年10月3－4日,采用夹捕法同时调查取食花生和山杏种子的鼠类种类及种群密度。于1997年9月24－25日,通过在地表放置山桔种子,调查在鼠类取食下,地表种子消失的速度。于1997年10月20日,作种子埋藏实验,调查种子存活及萌发情况。于1997年10月26日,进行扣网实验,研究网内、外山杏种子存活及萌发情况。结果表明：大林姬鼠（Apodemus speciosus)、社鼠（Rattus confucianus),黑线姬鼠（Apodemus agrarius)为取食山杏种子的主要鼠种种类;与取食花生相比,社鼠更偏爱山杏种子,大林姬鼠对山杏种子喜食性略低,黑线姬鼠对二者喜食程度相近;山杏种子放置地表后1、10、20、30d的消失率分别为13.06%,64.46%,90.70%,96.69%;扣网实验说明,山杏在地表的萌发率极低,生长也慢;而埋入土层内可明显提高萌发率和生长率（若除去鼠类的取食,萌发率还要高）;人工埋藏实验表明,将山杏种子埋入土层5cm后,能够有效地减少鼠类对种子的取食;通过分析山杏种子萌发与植被的关系,发现山杏易在开阔、阳光充分的草丛中存活和生长,而不易在阴闭的灌丛下存活和生长。     

食果鸟类对红楠种子的传播作用

肉质果植物通常依赖食果鸟类等取食果实后经消化道过程传播种子, 以完成种群的更新。红楠(Machilus thunbergii)是亚热带森林的代表性种类, 其果实具有依赖鸟类等动物取食后传播的特点。2012 年、2013 年在梅花山国家级自然保护区,研究了鸟类对红楠果实的取食及种子的传播作用。结果如下: 取食红楠种实的鸟类共计18 种, 其中整吞果实的鸟类12 种,啄取果肉的鸟类5 种, 啄食种子的鸟类1 种。整吞果实鸟类中4 种鹎科和2 种鸦科鸟类访问频次和取食量较大, 是主要的种子传播者。鸟类主要以呕吐方式传播种子。取食后初停栖点与母树距离及地面种子散布地点的分析结果表明, 鸟类可以远距离扩散种子。地面种实可被啮齿动物或蚁类再次捕食或搬运。研究表明, 红楠可以借助鸟类实现种子传播和种群更新。     

不同处理对普通野生稻种子萌发及水位对幼苗存活的影响

研究了江西东乡和湖南茶陵普通野生释（Ｏｒｙｚａ ｒｕｆｉｐｏｇｏｎ Ｇｒｉｆｆ．）种群的种子在不同处理下的发芽情况,以及水位对种子萌发和幼苗存活的影响。结果表明,变温处理极显著提高了种子的发芽率,去稃和去种皮以及去１／４胚乳后种子发芽率极显著提高;０～５ｃｍ水深有利于普通野生稻种子萌发和幼苗存活。２个种群的种子 芽率有左异,表明其种群间已存在遗传差异。     

鸟类对山黄麻种子的传播及其生态作用

在云南西双版纳的勐宋和勐仑地区观察和研究了传统山黄麻种子的鸟类。在野外持网捕获摄食山黄麻果实的鸟类,称量后分别放在布袋内,让其自然排泄,然后标志释放,观察和网捕共记录到摄食山黄麻果实的鸟类36种,其中26种挂网捕获并从排泄物得到种子。用鸟类排泄物中的山黄麻种子、山黄麻树上采摘的成熟果实及人工分离山黄麻种子播种,进行萌发对比实验,实验结果表明,直接播种成熟果实,在阳光充足的空旷地、林冠下或用树叶覆盖遮光等条件下都未萌发,种子容易霉烂或被虫蚀;从山黄麻果肉中分离出来的种子具有萌发能力;而经鸟类摄食、消化后从果肉中分离的种子,具有较好的萌发活力。在不同条件下山黄麻种子萌发情况差异明显,林冠下条件对种子有抑制作用,阳光作用下种子显示出很好的萌发及成活率。鸟类排泄物种子放在林上或用树叶覆盖遮光,经过较长时间便可萌发,而人工分离种子不能萌发。鸟类摄食及消化过程对山黄麻种子的处理表现出很好的生态互惠关系,观察萌发后的山黄麻幼苗的生长情况还表明,幼苗生长也需要光照和较开阔的生境条件,鸟类取食山黄麻果实及其将种子远距离传播适宜生境,正好具有这样的生态作用。     

啮齿动物的贮藏行为与植物种子的扩散

绝大多数啮齿动物一方面取食大量的植物种子和果实,另一方面通过其贮食行为将植物种子和果实搬运到远离母树的地点,即扩散,并将它们分散埋藏在落叶下或浅表的土层中,从而影响种子和果实的时空分布,最后导致幼苗在有利的条件下发生和建成,实现植物更新。啮齿动物与植物种子和果实之间已广泛形成了互惠或协同进化的关系。啮齿动物的贮食行为主要通过以下几个过程对植物种子和果实的扩散产生影响：选择、搬运和埋藏以及随后对种子和幼苗存活和死亡的影响等。本综述了啮齿动物对植物种子和果实贮藏的研究结果,以期为进一步开展啮齿动物的贮食行为在植物种子和果实的扩散中的作用的研究提供参考。     

影响杏黄兜兰种子萌发的因素

通过在不同条件下杏黄兜兰 (Paphiopedilumarmeniacum)种子萌发的观察 ,对影响其萌发的诸因子报道如下 :1)果实的生长期与种子的萌发率有关。实验表明种子采自生长期为 6 0d的果实 ,发芽率为 3 5 % ,采自 12 0d的果实 ,发芽率为 4 0 % ,采自 180d的果实 ,发芽率为 18 3%。 2 )培养基也会影响到种子的萌发 ,种子在 1 5MS内培养 ,萌发率明显高于培养于MS ,RE和改良HyponexNo 1内的种子。 3)培养基 (1 5MS)掺入添加物也会影响到种子的萌发率 ,如掺入 10 %椰子水会促使种子的萌发率达到很高的水平 ,掺入马铃薯泥 (5 0g L)或胰化胨 (2g L) ,种子的萌发率会达到较高的水平 ,而掺入香蕉泥则会对种子的萌发率产生负面影响 ,掺入活性炭 (2g L)会促使种子萌发和幼苗发育。 4 )与固态培养基相比 ,种子在液体悬浮培养基内的萌发速度更快 ,幼苗更为整齐划一。     

白及果实形态与种子结实率相关性研究

该研究以果实大小有明显差异的26个白及果序共87枚果实为材料,分析了果实形态(包括果实重量、长度及直径)与种子结实率的相关性。结果表明:果实重量与结实率的相关性最为密切,相关系数为0.786,达到中等正相关;其次是果实直径,相关系数为0.634;最后是果实长度,相关系数为0.553。对10枚果实及种胚大小测量结果显示,果实形态与种胚大小相关性为弱相关,不同果实种胚大小相差较大,种胚直径和种胚长度平均分别为177.9μm和359.0μm,最大分别为241.9μm和528.6μm,最小分别为64.5μm和114.3μm;单粒白及种子平均重3.90μg,87枚果实中,单枚果实平均种子数量为10 436粒,最大为39 488粒。该研究结果表明果实重量及饱满程度(直径),可以作为评价白及果实质量(种子结实率)的参考指标。     

应用结构方程模型解析影响黄连木果实产量 和种子命运的因素

果实(种子)产量和质量是影响植物种群更新的重要因素。为了探明影响黄连木果实产量和种子命运的因素以及这些影响因素之间的相互作用, 作者于2009年对河南省济源市45株黄连木(Pistacia chinensis)结果样树的植株特征、果实特征、果实产量和种子命运等进行了测定, 并用结构方程模型进行综合分析。结果表明: (1)黄连木果实产量与树高、树冠面积和果序大小等特征成正相关, 但与胸径、果实大小相关性不显著; (2)与捕食者饱和假说的预测不一致, 单株果实产量对黄连木广肩小蜂(Eurytoma plotnikovi)的种子捕食率(即虫蛀率)无显著直接负向效应; (3)树高和果实大小对虫蛀率为显著直接正向效应, 胸径对虫蛀率为显著直接负向效应, 显示黄连木广肩小蜂对植株特征和果实特征有一定的选择能力; (4)空壳率与虫蛀率成显著负相关, 空壳果实越多, 越易逃避黄连木广肩小蜂的寄生, 空壳果实的存在对完好种子起到了一定保护作用, 可能是黄连木防御昆虫寄生的重要机制; (5)空壳率和虫蛀率对种子完好率有显著直接负向效应, 而胸径、果序大小和果实产量对完好率为间接正向效应, 树高和果实大小为间接负向效应。可见, 黄连木植株特征和果实特征均不同程度地影响其果实产量和昆虫寄生, 从而影响黄连木的种子质量和种群更新。     

Long-term variation in seed mass and seed production in populations of Paris quadrifolia

Seed production of the perennial herb Paris quadrifolia L. (Liliaceae) was investigated in five populations in northern Poland. The long-term seed production per square metre differed significantly among populations and years. Moreover, throughout the 7-year study period, 30% of both whole ripe fruits and seeds alone were predated. Variation in seed mass per fruit in both space and time was significant. Throughout the 7-year study, nearly all the marked individuals produced fruits once every 2 years. The most frequent break between fruiting was 2 years and the longest was 5 years. Only the mean seed mass in fruits of the same individual varied significantly over subsequent years. In the five populations, the number of ovules, number of seeds in the fruit and seed mass varied significantly between populations. However seed/ovule ratio did not differ in fruits in the five populations. The seed mass/number trade-off in fruits was strongly partially correlated when the effect of total seed mass was considered. Breeding experiments suggest that P. quadrifolia has a substantial capacity for both inbreeding and outbreeding. There were no significant differences in the seed/ovule ratio, seed number or seed mass in fruits produced from bagged or control flowers. However, both seed/ovule ratio and number of seeds were significantly lower in fruits from emasculated flowers.     

Fruit size preference in the New Zealand pigeon (Hemiphaga novaeseelandiae)

Abstract We investigated whether the New Zealand pigeon Hemiphaga novaeseelandiae (Columbidae) exhibits size‐based preferences for fruits. We tested the hypothesis that in small‐fruited species, pigeons would prefer larger fruits, but in larger‐fruited species, this preference would reverse as the pigeons become increasingly limited by their gape size. We collected undispersed fruits and bird‐dispersed seeds of 10 plant species, some over several sites or years (13 datasets in total). We estimated the fruit size of dispersed seeds by fitting regressions of fruit diameter to seed diameter in intact fruits. We were able to predict fruit diameter from seed diameter in 12 of the 13 populations, although the relationship was stronger in single‐seeded species than in multi‐seeded species. Seven of the 12 populations tested showed a significant difference in seed diameter among undispersed and dispersed seeds. However, our results showed no consistent pattern in fruit size preference by the New Zealand pigeon and did not support our hypothesis. The large‐bodied New Zealand pigeon is generally not gape limited and fruit size preferences appear to be independent of mean fruit size.     

Variation in seed traits of Lobelia inflata (Campanulaceae): sources and fitness consequences

Seed germination constitutes an important event in the life cycle of plants. Two related seed traits affect fitness: seed size and the timing of seed germination. In three sets of experiments, we (1) partition the sources of seed-size variance in Lobelia inflata into components attributable to fruit size, relative fruit position, and parental identity; (2) examine the influence of pregermination conditions and seed size on time to germination; and (3) assess the fitness consequences of seed size and germination timing under seminatural, harsh conditions. Seed-size variance is attributable to both parental identity and fruit position within an individual. Distal fruits produce larger but fewer seeds. No significant correlation exists between fruit size and seed size, but a trade-off is found between the number and size of seeds contained in a fruit after correcting for fruit size. The timing of germination is influenced by seed size, light conditions before winter, and winter duration. Germination timing influences survival, and despite small seed size in this species (2 × 10 g/seed), seed size has a persistent and significant association with both final plant size and the probability of survival to autumn.     

Fruit Removal and Natural Seed Dispersal of the Brazil Nut Tree (Bertholletia excelsa) in Central Amazonia,Brazil

Experimental approaches to study seed dispersal of the Brazil nut tree have hitherto relied on exposed seeds deposited on the forest floor. Here we use a new method to study the natural dispersal by large rodents such as agoutis; tracking experimentally manipulated and tagged fruits containing individually marked seeds. Fruit manipulation did not deter agoutis from handling fruits. We found that agoutis usually moved intact fruits away from their original location below the parent tree before either hiding them or gnawing through the pericarp to access the seeds inside. Most fruits were moved to distances of 15–30 m from their original position, but some fruits could be taken as far as 60 m. A large number of seeds extracted from manipulated fruits appeared to be eaten immediately. Only 27 out of 1740 experimental seeds were found buried in shallow caches, generally within 5 m of the opened fruit. Fruit removal distance accounted for a disproportionate amount of total seed movement and seeds in the current study were dispersed significantly farther than in a previous experiment using exposed seeds, suggesting that classic dispersal experiments of this character may severely underestimate seed dispersal distances. We therefore conclude that the new method provides a more realistic and accurate approach to investigate natural seed dispersal of Brazil nuts and that the removal of fruits from underneath parent trees before being opened is the key to the significantly increased distances at which seeds are dispersed. Abstract in Portuguese is available at http://www.blackwell‐synergy.com/loi/btp .     

Proximate Limitations to Fruit and Seed Set in Phellodendron amurense var. sachalinense

Abstract Fruit and seed set in a dioecious tree, Phellodendron amurense var. sachalinense grown in isolation, were studied for three years in Hokkaido, northern Japan. Hand pollination did not affect fruit set during the three years, but did affect seed-set by increasing the proportion of fruits with higher seed numbers. Artificial defoliation resulted in decreased mean seed mass, but caused no significant differences in mean seed number per fruit. Total seed mass per infructescence increased with inflorescence size except with artificial defoliation where it reached an upper limit. Although the results of the artificial defoliation treatment indicate that resources are most important for fruit and seed set, it is concluded that fruit and seed set of the tree are not limited by resources, since the number of fruits increased with inflorescence size and an artificial defoliation treatment did not decrease seed-number.     

The Influence of Temporal Changes in Fruit Availability on Diet Composition and Seed Handling in Blue Monkeys (Cercopithecus mitis doggetti)1

We investigated the relation between temporally varying resources, diet composition, and seed-handling behaviors in a group of blue monkeys (Cercopithecus mitis doggetti) in a tropical montane forest of Rwanda. Changes in diet composition were related to concurrent phenological studies of fruit-producing trees, and density and abundance of tree resources within the monkey's home range. Fruit composed nearly 50 percent of the diet. Over 50 percent of the fruits eaten had juicy fleshy pulp. Observations of seed handling behavior provided insights into the role of these animals as potential seed dispersal agents. The monkeys moved the seeds of 29 species out of parent canopies by defecating seeds intact and by potentially carrying seeds in cheek pouches and dropping them later. Seeds of 18 species were found intact in fecal piles. Our study showed community-level phenology patterns did not indicate a decrease in fruit availability during the study period, but an analysis of the preferred fruits consumed by the monkeys showed distinct periods of low fruit availability. The study period included two dry seasons; only one of these produced a period of fruit scarcity for the animals. The animals employed different strategies during times of preferred fruit scarcity. They increased consumption of leaves and other fleshy fruits, and diet diversity increased, or became mainly seed predators and diet diversity decreased. The variable responses of these monkeys to changes in food availability highlights their dietary plasticity and imposes significant variations in their role as potential seed dispersers.     

Morphology and phenology of seeds and whole fruit eaten by Milne-Edwards’ sifaka,Propithecus diadema edwardsi,in Ranomafana National Park,Madagascar

Although it is an anatomical folivore, the diet of the Milne-Edwards’ sifaka (Propithecus diadema edwardsiA. Grandidier, 1871) in Ranomafana National Park contained 35% seeds, 30% whole fruit, and 28% leaves. Plant species used as seed sources differed from those used as whole fruit sources in terms of temporal variation in consumption, taxonomic affiliation, morphology, and phenology. Although seeds were destroyed in both exploitation styles used by the sifakas—seed and whole fruit-eating—the gross morphology of species used as seed sources conformed to the complex of traits typical for fruits experiencing seed predation, while species used as whole fruit sources conformed to traits typical for fruits that do not experience predispersal predation. Many of the 19 plant species from which the seed was extracted and eaten contained a single seed with moderate testa thickness, and fruits containing this type of seed were medium-sized with dry or fibrous flesh, moderate skin thickness, and a dull color. In contrast, brightly colored, juicy fruits with minimally protected seeds were characteristic of the 38 plant species from which both pericarp and seed were eaten. Compared to transectwide measures of fruit availability or patterns restricted to whole fruit sources, fewer species of seed sources produced fruit per month and fruiting activity was more seasonal.     

Fruit Traits in Baboon Diet: A Comparison with Plant Species Characteristics in West Africa

Primate fruit choice among plant species has been attributed to different morphological plant and fruit characteristics. Despite a high abundance of animal-dispersed plant species in the savanna–forest mosaic of West Africa, few data are available on the interplay between morphological fruit traits and primate fruit consumers in this ecosystem. We tested whether olive baboons (Papio anubis) at Comoé National Park, north-eastern Ivory Coast, prefer fruit species with particular characteristics relative to the availability of these traits among the woody plant species at the study site. Specifically we were interested in the suites of traits that best predict fruit choice and seed handling by baboons. The baboons ate fruit/seeds from 74 identified plant species, representing 25 percent of the regional pool of woody plant species. They preferred trees to shrubs and lianas as fruit sources. Otherwise, baboons seemed to consume whatever fruit type, color, and size of fruit and seeds available, though they especially included larger fruit into their diet. Against expectations from the African bird–monkey fruit syndrome of brightly colored drupes and berries, baboons ate mostly species having large, dull-colored fruit. Fruit type and color best described whether baboons included a species into their diet, whereas fruit type and seed size best predicted whether baboons predated upon the seeds of their food plant species. As most plant species at the study site had medium-sized to large fruits and seeds, large frugivores like baboons might be particularly important for plant fitness and plant community dynamics in West African savanna–forest ecosystems.