关键词： 卡耐基  

摘要： 钢铁大王卡耐基去往纽约市中心一幢高层建筑物,他要乘电梯到高层一间写字间。电梯里,他遇上了一位开电梯的人,这人的左手被齐腕砍断。于是,他问这位没有手的人,会不会因为没有手感到难过。得到的答案,让卡耐基大感意外,开电梯的人说:"噢,不会,我根本就不会想到它。只有在要穿针的时候,才会想到这件事。"举重若轻,诙谐幽默。谁会真的相信,没有手的人,只会在穿针的时候才想到手。只是生活中趋利避害的法则告诉人们,对已经发生的或必

关键词： Browser   Bush encroachment   Nutrients   Woody structure   Livestock   Wildlife  

摘要： The structure and composition of woody and grassy vegetation in savannas is strongly influenced by herbivores. In recent decades, the proportion of browsers has declined across African savannas in favour of more grazers, triggered by large-scale human-induced cattle grazing. This has led to overgrazing and an imbalance of woody and grassy vegetation. Our study investigated mono-specific and multi-species herbivore assemblages of varying density and assessed similarities in vegetation patterns under wildlife and livestock herbivory in and around Kruger National Park, South Africa. Under mono-specific herbivory, overall tree cover was more than twice as high compared to multi-species herbivory while the branch. ing height of small and tall trees was lowest. Small tree and bush densities were strongly elevated at mono-specific compared to multi-species herbivore sites. Tall trees were dominated by Acacia nigrescens under multi-species herbivory at low wildlife density but not at high density sites. Grass leaf nitrogen contents were almost twice as high at multi compared to mono herbivory sites, particularly beneath tree canopies. Livestock and wildlife herbivore sites showed similar patterns in their woody plant structure and grass nutrients. We conclude that a characteristic herbaceous and woody vegetation structure as well as species composition can be matched with mammalian herbivore communities, which has implications for landscape heterogeneity and grazing management in savanna systems. (C) 2014 Geobotanisches Institut ETH, Stiftung Ruebel. Published by Elsevier GmbH. All rights reserved.

关键词： 咽鼓管   分泌性中耳炎   动物模型   电凝堵塞  

摘要： 目的:研究树鼩咽鼓管解剖结构,行树鼩头颅Micro-CT扫描;建立分泌性中耳炎的树鼩动物模型。方法:选取26只健康成年树鼩作为实验对象,分成2组(解剖组和模型组)解剖组(树鼩咽鼓管解剖及micro-CT扫描):选取10只健康成年树鼩,进行显微解剖,其中6只行micro-CT扫描,通过mimics15.0软件对micro-CT扫描数据进行分析。模型组(树鼩分泌性中耳炎模型的建立):选取16只健康成年树鼩,采用电凝法堵塞咽鼓管咽口建立分泌性中耳炎模型,所有动物右耳为实验耳,左耳为对照耳。造模后第3天进行耳显微镜检查、第3天行声导抗检查、第10天行MicroCT检查,于造模后第7天、第28天行中耳病理检查。结果:1.解剖组:解剖显微镜下发现:1.1.咽鼓管大体形态树鼩咽鼓管是一管状结构,咽鼓管咽口位于鼻咽外侧壁,其上方为颅底,下方为软腭,前方为后鼻孔,后方为鼻咽及口咽交界处,鼓室口位于中鼓室前上部,在鼓室前壁与内壁交界处向前下方鼻咽部方向走行。1.2.咽鼓管管壁构成树鼩咽鼓管分为三部分:粘膜部、软骨部和骨部。在咽鼓管的横截面上,咽鼓管软骨呈“C”形。软骨部和骨部交界处为咽鼓管最狭窄处。1.3.腭帆张肌(TVP)腭帆张肌由二组肌肉纤维组成,内组较大,起源于听泡、蝶骨大翼、翼状突,外组较小,起源于软骨外侧板,接近软骨部和骨部交界处。1.4.腭帆提肌(LVP);腭帆提肌起源于软骨内侧板近软骨部和骨部交界处.肌肉束向前内方向走形,最后融入到软腭后方.*** CT扫描结果显示:MicroCT扫描可清晰显示骨性结构,颅骨、硬腭、鼻甲、听泡、听骨、耳蜗等结构。但对软组织显示较差。Micro-CT扫描发现:树鼩听泡分为,内、中、外三个气房,外侧听泡较大,中间听泡较小。咽鼓管咽口黏膜部位于内听泡外侧,咽鼓管鼓口开口位于外听泡内侧,软骨部全长贯穿于内听泡。咽鼓管骨部位于外侧听泡。咽鼓管狭窄部位于内听泡与外听泡间隔处。2.模型组:2.1.耳显微镜观察鼓膜情况:实验耳(右耳)鼓膜颜色呈橘黄色,鼓室内可见积液存在。在对照耳(左耳)鼓膜正常,鼓室内无积液。2.2.声导抗鼓室图:实验耳声导抗鼓室图均显示为“B型”。在对照耳声导抗鼓室图均显示为“A 型”。***-CT 扫描结果:通过Micro-CT图像对树鼩手术耳侧进行影像学观察。所有树鼩实验耳的听泡内可见积液存在,符合分泌性中耳炎的征象。在所有的对照耳中未发现明显积液存在。2.4.病理检查;第7天:通过显微镜观察到中耳内部有白细胞浸润现象,粘膜层扩张,有大量的破骨细胞和成骨细胞出现。骨细胞和成骨细胞的数量增加表明出现骨膜增生。另外,纤维细胞和胶原纤维细胞的数量有所增加,上皮细胞层出现的血管扩张、水肿和淋巴细胞导致中耳粘膜增厚。第28天:用光学显微镜观察到,中耳粘膜厚度与第7天时的厚度相比增厚,同时也出现了水肿,这是慢性传染的症状。所有动物的炎症细胞的数量和在第7天时的数量相比有所增多。结论:1.树鼩咽鼓管分为粘膜部、软骨部和骨部;管周肌肉主要是腭帆张肌和腭帆提肌;树鼩咽鼓管的观察结果可为进一步研究咽鼓管功能以及病理生理变化提供解剖学依据。2.通过鼓膜观察、鼓室导抗图、颞骨Micro-CT及中耳病理检查,证实电凝法堵塞咽鼓管咽口,能有效诱发树鼩分泌性中耳炎,此动物模型可作为进一步研究分泌性中耳炎发病机制、诊断及治疗的模型。

关键词： manipulative experiment   mark-recapture   predator-prey interactions   predator-proof fences   reintroduction   small-mammal extinction   survival  

摘要： Small mammal species are declining across northern Australia. Predation by feral cats Felis sylvestris catus is one hypothesised cause. Most evidence of cat impacts on native prey comes from islands, where cat densities are often high, but cats typically occur at low densities on mainland Australia. We conducted a field experiment to measure the effect of predation by low-density cat populations on the demography of a native small mammal. We established two 125-ha enclosures in tropical savanna in the Northern Territory. Each enclosure was divided in half, with cats allowed access to one half but not the other. We introduced about 20 individuals of a native rodent, Rattus villosissimus, into each of the four compartments (two enclosuresxtwo predator-access treatments). We monitored rat demography by mark-recapture analysis and radiotracking, and predator incursions by camera surveillance and track and scat searches. Rat populations persisted over the duration of the study (18months) in the predator-proof treatment, where we detected no predator incursions, but declined to extinction in both predator-accessible compartments. In one case, cat incursions were frequently detected and the rat population was rapidly extirpated (<3months);in the other, cat incursions were infrequent, and the population declined more gradually (c. 16months) due to low recruitment. We detected no incursions by dingoes Canis dingo, the other mammalian predator in the area. Synthesis and applications. This is the first study to provide direct evidence that cats are capable of extirpating small mammals in a continental setting, in spite of their low population densities. This finding supports the hypothesis that predation by feral cats is contributing to declines of small mammals in northern Australia. The conservation management of native small mammals in northern Australia may require intensive control of cat populations, including large cat-free enclosures.

关键词： Abundance   Amazon savanna   Brazil   Medium and large mammals   Richness  

摘要： In this study, we investigated the effects of the partial conversion of native Amazon savanna into a eucalyptus plantation on the richness, composition, and abundance of medium and large mammals. Considering these plantations as an integral component of a patchwork savanna landscape, we verified how the negative effects of these plantations can be buffered by the conservation of remnants of native habitat within their area. We analyzed the contribution of each type of Amazonian savanna to the maintenance of the mammalian fauna and the potential of eucalyptus plantations to substitute these native habitats. A total of 23 mammal species were recorded in line-transect surveys conducted within the conserved savanna. By contrast, only eight species were recorded in the eucalyptus plantation and none of them were exclusive to this vegetation. However, the landscape patchwork formed by plantations and savanna was more diverse and contained 19 species of mammals, highlighting the potential importance of remnant savanna vegetation. The maintenance of remnants of savanna habitat may thus be essential for ensuring the conservation of mammals in the anthropogenic landscape of this region. It will also be important to include as many different subtypes of native savanna vegetation as possible and to consider the connectivity between habitats.

关键词： Dendrometer   Dichrostachys   Elephant   Exclusion experiment   Long-term monitoring   Survival  

摘要： Seasonality is a characteristic feature of savannas. Assuming plants are dormant in the dry season, long-term browsing by large herbivores (or their exclusion) in savannas should affect stem growth in the wet season alone. In addition, plant survival should improve with exclusion. A total of 236 dendrometers on six woody species in three large (> 25 ha) plots (all large herbivores excluded, elephants excluded, control-no large herbivores excluded) were observed from 2006 to 2013 in Kruger National Park, South Africa. Average monthly increment (AMI) per dendrometer was calculated and the interaction between exclusion and season (dry or wet) was tested species-wise. The AMIs of Acacia exuvialis, Combretum apiculatum, Dichrostachys cinerea and Grewia flavescens were generally reduced by herbivore exclusion, while the unpalatable Euclea divinorum was unaffected. Survival rates of C. apiculatum and E. divinorum were not significantly associated with exclusion, while other species' survival rates benefitted from exclusion. The dry-season AMIs of all species were significantly lower than wet-season AMIs, but dry-season AMIs were positive for two species common on footslopes (A. grandicornuta and E. divinorum), while being almost zero for species common on midslopes and crests, possibly because of hydrological variation on the catena. The results suggested that stem circumference growth of prominent woody species in semi-arid savannas is prone to reduction by exclusion of large herbivores, except for generally unpalatable species. Large herbivores may affect woody stem growth in semi-arid savannas by altering competition among plants.

关键词： camera traps   drylands   invasive   Prosopis   riparian   wildlife  

摘要： Ephemeral rivers and the vegetation they support have numerous ecological and economic values to the mammals and people who rely on these systems. Yet, these crucial environments are believed to be threatened by exotic plant invasion. In Africa, invasive trees of the genus Prosopis have detrimental effects on native vegetation, bird and dung beetle communities;however, to date, there is no evidence that Prosopis establishment has affected indigenous wild mammalian distribution and ecology in its introduced range. Using a combination of camera traps and vegetation surveys, we tested the hypothesis that Prosopis invasion has a negative impact on the mammals of the ephemeral Swakop River in Namibia by reducing mammal species richness and species occupancies. Prosopis was found to have no negative impact on species richness;however, evidence for species-specific responses to Prosopis abundance was found. This is the first study to confirm an impact of Prosopis on sub-Saharan African mammals, providing a foundation for future research and the development of appropriate management policy.

关键词： Acacia   Acacia   Animals   Antelopes   Canidae   Food Chain   Food Chain   Geographic Information Systems   Herbivory   Panthera   Predatory Behavior   Trees  

摘要： Understanding how predation risk and plant defenses interactively shape plant distributions is a core challenge in ecology. By combining global positioning system telemetry of an abundant antelope (impala) and its main predators (leopards and wild dogs) with a series of manipulative field experiments, we showed that herbivores' risk-avoidance behavior and plants' antiherbivore defenses interact to determine tree distributions in an African savanna. Well-defended thorny Acacia trees (A. etbaica) were abundant in low-risk areas where impala aggregated but rare in high-risk areas that impala avoided. In contrast, poorly defended trees (A. brevispica) were more abundant in high-than in low-risk areas. Our results suggest that plants can persist in landscapes characterized by intense herbivory, either by defending themselves or by thriving in risky areas where carnivores hunt.

关键词： Africa   Arthropod   Community   Diversity   Mistletoe   Savanna  

摘要： The below-canopy soil moisture content and litter-layer arthropod abundance and diversity of Acacia karroo trees parasitized by each of three mistletoe species (Erianthemum ngamicum, Plicosepalus kalachariensis, and Viscum verrucosum) and uninfected A. karroo trees were investigated in semi-arid savanna, southwest Zimbabwe. The soils below the canopies of mistletoe-infected trees were significantly low in moisture content compared to those beneath uninfected A. karroo trees. Nevertheless, arthropod species diversity was greater by up to 34 % below the canopies of mistletoe-infected trees than beneath uninfected A. karroo trees, with greater abundances beneath trees infected by E. ngamicum and P. kalachariensis. In addition, the majority of the arthropod species associated with mistletoe-infected trees had litter as their dominant foraging substrate. Our findings show that mistletoes increase the abundance and diversity of litter-dwelling and -foraging arthropods due to increase in the quality and quantity of litterfall beneath mistletoe-infected trees. By altering the below-canopy arthropod communities and soil moisture content, mistletoes have potential to modify ecosystem processes such as decomposition, soil process rates, and nutrient cycling. Therefore, we suggest that the resulting increase in resource heterogeneity plays an important role in determining the structure and functioning of semi-arid savanna ecosystems.

关键词： BEF-China   biodiversity effects   Formicidae   Gutianshan National Nature Reserve   soil properties   species diversity   trophic guilds   vegetation structure  

摘要： 1. Epigeic ants are functionally important arthropods in tropical and subtropical forests, particularly by acting as predators. High predation pressure has been hypothesised to be a mechanism facilitating high diversity across trophic levels. 2. In this study, standardised pitfall traps were used in a highly diverse subtropical forest to test if and how ant species richness is related to tree species richness and a comprehensive set of other environmental variables such as successional age, soil properties or elevation. 3. A total of 13 441 ant individuals belonging to 3839 species occurrences and 71 species were collected, of which 26 species were exclusive predators and 45 species were omnivores. 4. Occurrence and species richness of total and omnivore ants were positively related to soil pH. Predator ant occurrence was unrelated to all environmental variables tested. 5. The species richness of predator ants increased with tree species richness but decreased with leaf functional diversity and shrub cover. Elevation negatively influenced only total ant species richness. 6. The evenness of predators increased with tree species richness, while the evenness of all ants decreased with shrub cover. Omnivore ant evenness decreased with tree evenness, but increased with successional age. 7. The results highlight the value of diverse forests in maintaining species richness and community evenness of a functionally important predator group. Moreover, the results stress the importance of analysing trophic groups separately when investigating biodiversity effects.