Avian seed dispersal and seedling distribution of the endangered tree species,Taxus chinensis,in patchy habitats

Background: There is limited understanding about bird dispersal behaviour and seedling distribution of endangered tree species in patchy environments, although these processes are important for plant species persistence.

Aims: We tested how patch features affected bird behaviour and seed dispersal, and thus seedling distribution of the endangered Chinese yew tree (Taxus chinensis).

Methods: In the present study, we combined field data of bird dispersal behaviour and GIS-based information to elucidate the influence of spatial features of habitat patches on bird dispersal behaviour, and the resulting effects on the seedling distribution of the endangered Chinese yew in two patchy habitats.

Results: Our results showed that the only seed source patch could attract eight bird species for dispersal at the two sites. Post-foraging movements of bird dispersers was strongly related to both topography and the relative locations of habitat patches. Yew seedlings aggregated only at the seed source and bamboo recruitment patches, which was affect by both the spatial distribution of recruitment patches and patch use by dispersers.

Conclusions: Our results emphasise that bamboo patches in both patchy environments provide the necessary conditions for germination of yew seeds, and the post-foraging behaviour of dispersers determines seed deposited in these patches. Our study highlights the importance of the dispersal behaviour of frugivorous birds in the successful regeneration and colonisation of yew populations in patchy habitats.     

浙江天童山鼠类对栲树种子的捕食和扩散

在浙江天童山国家森林公园,研究了鼠类在常绿阔叶林、马尾松林和灌丛几种生境内对栲树（Castanopsis fargesii）种子的捕食和扩散的影响.结果表明,社鼠（Niviventer confucianus）和针毛鼠（N.fulvescens）是栲树种子的主要捕食者.种子在刚布下后的几天内消失的最快,随后其日消失率便逐渐降低,在不同生境中,其日消失率也有所不同,在灌丛中日消失率最高（7.54%）,其次是马尾松林（7.29%）,而常绿阔叶林中3条样带的日消失率较低.在损失的种子中,各种种子命运所占比例在样带中存在着差异,灌丛中失踪的种子比例最高,占97.77%,而样带2的则最低,只占8.91%.这与不同样带中的植被组成密切相关.同时,鼠类对栲树种子扩散的距离比较近,观察到的最远扩散距离为12.7 m.     

动物对花楸树种实的取食与传播

花楸树是我国东北林区重要的非木质资源树种,其种实既有自然散布方式,也有动物散布方式.本文通过对花楸树种实散布过程中动物活动特点的研究,探索动物取食和传播花楸树种实的规律及其对花楸树天然更新的影响.在2008和2009年花楸树果实成熟期,通过定期观察取食花楸树果实的鸟类及其取食方式,确定对花楸树果实有拜访行为的鸟类有8种,其中食果肉鸟类斑鸫、灰喜鹊和白背啄木鸟对花楸树种实有传播作用,它们对花楸树果实的拜访频率分别为54%、12%和7%,取食后第一落点集中于距离母树5～10 m之间（占68.2%）,其次为距离母树5 m以内（占27.3%）,距离母树10 m以外的比例很小（占4.5%）.果实在鸟类消化道内的滞留时间可达20 min,表明潜在传播距离会很长.人工摆放果实和种子试验表明,在不同生境地面摆放的果实6～7 d内全部消失,果实的取食者主要是啮齿类和地面取食的鸟类,取食率均较高（50%～70%）;种子的取食者为啮齿类、地面取食的鸟类和蚁类,取食率均较低（1%～5%）.花楸树为多种动物提供食物,而动物为花楸树传播种子,动物的取食对花楸树的天然更新有重要影响.     

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     

不同干扰强度生境中啮齿动物对苦槠种子的取食和扩散

在浙江省千岛湖地区,选择了受人类活动干扰较轻、中度和严重的3个生境,采用金属片标记法研究了啮齿动物对苦槠种子的取食和扩散.结果表明:在研究点捕获的取食种子的啮齿动物为针毛鼠( Niviventer fulvescens),尽管捕获的数量少,但种子被取食和扩散的速率很快,3个样地内的种子均在2d内被取食或扩散完毕;中等干扰强度的生境中,被就地取食的种子最多,占鉴别种子总数的37.8%.种子扩散距离大多<5m,最大扩散距离为24.76m,3个样地种子扩散均符合负指数分布,且样地间没有显著差异;饱满种子与虫蛀种子被就地取食与搬运后取食的命运没有显著差异,但饱满种子的最大扩散距离均显著大于虫蛀种子(P<0.05),除中等干扰样地中饱满种子与虫蛀种子平均扩散距离没有显著差异外,其余2个样地中饱满种子的平均扩散距离均显著大于虫蛀种子,显示啮齿动物对饱满种子与虫蛀种子有一定的区分能力.     

鸟类取食中国沙棘果实的方式及其对种子的传播作用

2003年9月～2004年3月,定期观察取食中国沙棘果实的鸟类及其取食方式。共记录取食中国沙棘果实的鸟类18种,其取食果实的方式主要有：1)直接在树冠上吞食果实,有时候在吞食后将种子呕出;2)将果实从树上衔走后,在栖息处吞食或啄食;3)将果实啄落至地面,然后取食果肉和种子,留下果皮;4)啄破果皮,吸食果肉,留下果皮及种子;5)从顶端将果皮啄破后,仅取食里面的种子。不同的取食方式决定了它们对沙棘种子的传播作用不同。收集鸟粪便中的种子与完整的干果实及人工剥离果肉和内果皮的种子做萌发对比实验,结果表明,鸟类消化道过程对种子的萌发有一定影响,但萌发率仍较高。沙棘为多种鸟类提供食物,而鸟类则为沙棘传播种子,它们之间形成一种互利关系。     

Characterization of animal communities involved in seed dispersal and predation of Guibourtia tessmannii (Harms) J.Léonard,a species newly listed on Appendix II of CITES

Characterization of the ecology of endangered timber species is a crucial step in any forest management strategy. In this study, we described the animal communities involved in seed dispersal and predation of a high‐value timber species Guibourtia tessmannii (Fabaceae; Detarioideae), which is newly listed on Appendix II of CITES. We compared the animal communities between two forest sites (Bambidie in Gabon and Ma'an in Cameroon). A total of 101 hr of direct observations and 355 days of camera trapping revealed that a primate (Cercopithecus nictitans nictitans) and a hornbill (Ceratogymna atrata) were important seed dispersers in Gabon. Conversely, a greater presence of a rodent (Cricetomys emini), which could act both as predator and disperser, was observed in Cameroon. This study suggests that animal communities involved in seed dispersal of G. tessmannii may vary depending on environmental conditions and anthropogenic impacts. However, further studies are needed to properly identify the factors involved in seed dispersal and predation of G. tessmannii.     

Fruits foraging patterns and seed dispersal effect of frugivorous birds on Hippophae rhamnoides sinensis

Behaviors of 18 species of birds eating fruits of Hippophae rhamnoides spp.sinensis were observed from September 2003 to March 2004.Their foraging patterns were found to be very different and Can be divided into five classes:(1)direct swallowing the fruits on crown of the shrubs and sometimes regurgitating seeds soon after;(2)carrying the fruits to their perching sites and swallowing;(3)pecking the fruits from the shrubs to the ground,eating pulp and seeds but leaving pericarp;(4)pecking through the pericarp,eating pulp and leaving pericarp and seeds;(5)pecking through the pericarp on the top of fruits,and only eating seeds.These foraging patterns have different effects on seed dispersal of H.rhamnoides spp.sinensis.The germination experiment of three groups of seeds(seeds from feces,dry fruits and extracted seeds from dry fruits)was carried out.Although ingestion processes of birds had some adverse effects on the seed germination of H.rhamnoides spp.sinensis,the seeds from feces still have a relatively higher germination ratio.H.rhamnoides spp.sinensis provides food to a variety of frugivorous birds.and the birds disperse its seeds.Thus,a mutually beneficial relationship between the bird and the seed is formed.     

南京中山植物园春夏季节鸟类对植物种子的传播作用

2002年4月至8月,在南京中山植物园内收集了198份鸟粪样品,从中分离、鉴定出9 573粒结构完整的种子及果核,分别隶属于12科15属20种植物,另有1 6粒种子属于1未知种类.单份鸟粪样品中可含有1～4种种子,平均1.5±0.7种;但单份鸟粪样品中种子数量变化很大,约为1～583粒,平均48.4±70.7粒.鸟粪样品中出现频次较高的种类主要有构树(Broussonetia papyrifera)、蛇莓(Duchesnea indica)、桑树 (Morus alba)、山莓(Rubus corchorifolius)、日本珊瑚树(Viburnum awabuki)、蓬FDA1(Rubus hirsutus)和美洲商陆(Phytolacca americana)等7种,并且它们的种子数量也多达9 213粒,占种子总数的96.1%.鸟粪样品中种子出现频次的月份变化也在一定程度上间接地反映出植物果实的成熟期和鸟类对果实的取食频率.白头鹎(Pycn onotus sinensis)、乌鸫(Turdus merula)等鸟类则主要以呕出种子的方式传播桂花(Osmanthus fragrans)、白玉兰(Magnolia denudata)等体积较大的种子.此外,鸟类还以衔取果实的形式传播种子.2000～2002年,已经观察到8种鸟类取食18种植物的肉质果实,其中灰喜鹊(Cyanopica cyana)、乌鸫、白头鹎和山斑鸠(Streptope lia orientalis)等4种留鸟分别取食8～16种植物果实,是春夏季节植物园内取食果实种类数目较多的鸟类,并且也可能是重要的种子传播者.鸟类传播种子已经导致了阔叶十大功劳(Mahonia bealei)、樱桃(Cerasus pseudocerasus)、掌叶复盆子(Rubus chingi i)和桂花等栽培树种逸出植物园,使它们的实生苗及小树成功地侵入到植物园周围的自然生境中,促进了植物园内一些具肉质果实的栽培植物的自然更新.同时,鸟类传播种子也是导致美洲商陆等引种栽培植物逸生为外来杂草并迅速蔓延的重要原因之一.     

Response of ants to human‐altered habitats with reference to seed dispersal of the myrmecochore Corydalis giraldii Fedde (Papaveraceae)

Anthropogenic habitat disturbance has potential consequences for ant communities. However, there is limited information on the effects of ant responses on associated ecological processes such as seed dispersal. We investigated the effect of disturbance on the abundance, richness, and composition of ant communities and the resulting seed‐dispersal services for a herbaceous myrmecochore, Corydalis giraldii (Papaveraceae), in an undisturbed habitat (forest understory), moderately disturbed habitat (abandoned arable field), and highly disturbed habitat (road verge) on Qinling Mountains, China. In total, we recorded 13 ant species, and five out of these were observed to transport seeds. The community composition of dispersers was significantly different amongst habitats. The richness of the dispersers did not differ among the habitats, but their total abundance varied significantly across habitats and was 21% lower in the road verge than in the abandoned arable fields. The major seed‐dispersing ant species in both the forest understory and the abandoned arable field were large‐bodied (Myrmica sp. and Formica fusca, respectively), whereas the major seed‐dispersing ants found in the road verge were the small‐bodied Lasius alienus. This difference resulted in lower seed removal rates and dispersal distances in the road verge than in the other two habitats. The different dispersal patterns were attributed primarily to differences in dispersing ant abundance and identity, most likely in response to habitats with different degree of anthropogenic disturbance. The possible influence of disturbance on the ecological specialization of ant‐seed dispersal interaction is also discussed.