埋藏点深度、间距及大小对花鼠发现向日葵种子的影响

2005 年5 ～6 月,在北京东灵山地区,通过在实验围栏内设置不同深度、间距和大小的埋藏点,研究了花鼠对向日葵种子的发现率。结果表明,花鼠发现埋藏种子的比例随埋藏深度的增加而减少,埋藏深度> 5 cm后,发现比例较低,且不再有明显变化;花鼠发现埋藏种子的比例随埋藏点间距的减小而增加,埋藏点间距<0.5 m后,发现比例较高,且不再有明显变化;花鼠发现埋藏种子的比例随着埋藏点增大而增加,埋藏点种子> 5 g后,发现比例较高,且不再有明显变化。     

围栏条件下花鼠找寻种子的途径和方式

2009年8月和2010年8月,在黑龙江省带岭区东方红林场半天然围栏内研究了花鼠(Eutamias sibiricus)对地表放置和埋藏种子的发现过程,摸清围栏条件下花鼠找寻种子信号的途径和方式.实验步骤如下:第1天在花鼠巢区对角每释放点地表放置1粒标记种子,共30粒;第2天在巢区对角每释放点埋藏1粒标记种子,共30粒...     

同种或异种干扰对花鼠分散贮藏点选择的影响

同种和异种干扰竞争可以增强花鼠(Tamias sibiricus)分散贮食强度,但对其贮藏点选择的影响还不清楚.在半自然围栏内,研究了同种(干扰源为不同性别花鼠)或异种(干扰源为大林姬鼠,Apodemus peninsulae)干扰竞争对花鼠贮藏点选择的影响.结果发现:(1)同种和异种干扰竞争均显著降低了花鼠在高竞争区内的贮藏比例;(2)同种个体存在时,雌性花鼠显著降低了在高竞争区内的贮藏比例,雄性花鼠则显著增加了在中竞争区的埋藏比例.结果表明,花鼠贮藏食物时会避开高竞争区域以降低同种或异种的盗食损失,同时雌雄个体对同种竞争干扰的响应有所差异.     

种内及种间干扰对围栏内花鼠分散贮藏行为的影响

2009 年9 月在黑龙江省带岭区东方红林场10 m ×10 m 半天然围栏内模拟花鼠种内(不同性别) 和种间
(大林姬鼠) 干扰竞争对花鼠分散埋藏红松种子行为的影响。实验分四个处理两个批次进行,依次为单只花鼠对
照实验(雄性7 只,雌性9 只)、种内同性干扰竞争、种内异性干扰竞争和种间干扰竞争。结果表明:(1)花鼠
雌性个体的分散埋藏强度明显高于雄性个体;(2)种间干扰竞争引起花鼠对红松分散埋藏比例明显增加,而种
内干扰对花鼠分散埋藏行为的影响不显著;(3) 种内干扰竞争条件下,同性干扰竞争和异性干扰竞争对花鼠分
散埋藏行为均无显著影响;(4)雄性个体在同性干扰下,埋藏强度不变;而在雌性个体干扰竞争下,埋藏强度
增加;(5)雌性个体在雌性和雄性干扰条件下,花鼠分散埋藏行为均无明显变化。     

岩松鼠贮藏种子的空间记忆研究

通过在岩松鼠自身埋藏种子附近选择相同生境人工埋藏种子的方法,研究岩松鼠对自身埋藏种子和人工埋藏种子的找回率有无差异,从而部分揭示记忆如何在岩松鼠找回贮藏种子过程中发挥作用。数据的统计分析采用SPSS for Windows(version 19.0)进行。结果显示:1)岩松鼠喜欢将种子贮藏在灌丛下方,但对埋藏基质没有明显偏好;2)埋藏微生境和埋藏基质对岩松鼠在对人工埋藏种子的找回过程中没有明显影响;3)岩松鼠对人工埋藏的核桃种子在种子找回过程中与自身埋藏的核桃种子有显著差异(Z=-2.499,P=0.014),对人工埋藏的胡桃楸种子在找回过程中与自身埋藏的胡桃楸种子有极显著差异(Z=-6.557,P<0.001)。     

种子类别和埋藏深度对雌性小泡巨鼠发现种子的影响

2001年9～12月,在四川省都江堰林区实验围栏内研究了栓皮栎、袍树、栲树、石栎、青冈和油茶种子与6种埋藏深度对小泡巨鼠雌性成体发现埋藏种子的影响。结果表明：1)由于不同种子在种子大小、营养价值和单宁含量等存在差异,雌性小泡巨鼠对个体最大的石栎种子发现率最高,油茶(脂肪含量高)和栲树(单宁含量低)次之,单宁含量较高的袍树、青冈和栓皮栎则较低;2)埋藏深度与雌性小泡巨鼠发现栓皮栎种子的比例呈显负相关,即随着埋藏深度增加,小泡巨鼠发现埋藏种子的比例则减少。     

围栏条件下影响岩松鼠寻找分散贮藏核桃种子的关键因素

在北京东灵山地区半自然围栏内,通过将核桃(Juglans regia)种子用塑料袋封闭处理减弱嗅觉信号和埋藏处理阻断视觉信号,研究了岩松鼠(Sciurotamias davidianus)对置于地表、埋藏、封闭后置于地表和封闭后埋藏核桃种子的发现率,以探讨岩松鼠找寻种子的主要方式;同时还研究了岩松鼠对自己埋藏和其他个体埋藏种子的发现率,以探讨空间记忆在岩松鼠找寻自己埋藏种子时是否有重要作用。岩松鼠对各组种子的发现率为:埋藏组59.5±27.6%,地表组53.3±27.7%,封闭埋藏组31.0±27.2%,封闭地表组26.3±28.6%;其中埋藏组与地表组较高,差异不显著(Z=-0.356,P=0.722),封闭埋藏组和封闭地表组较低,差异也不显著(Z=-0.493,P=0.622),即通过埋藏处理阻断视觉信号对岩松鼠的种子发现率没有显著影响;埋藏组显著高于封闭埋藏组(Z=-2.943,P=0.003),地表组显著高于封闭地表组(Z=-2.084,P=0.037),即通过封闭处理减弱嗅觉信号显著减少了岩松鼠对种子的发现率;当种子被封闭且埋藏时,有31.0%的种子被找到,即当通过封闭处理减弱嗅觉信号,埋藏处理阻断视觉信号后,岩松鼠仍能通过随机探索找到部分种子。自埋组(57.9±21.8%)和他埋组(54.4±33.9%)的种子发现率都较高,且差异不显著(Z=-0.157,P=0.875),即岩松鼠在找寻自己埋藏的种子时没有明显优势。这些结果表明:围栏条件下,嗅觉在岩松鼠找寻贮藏种子时起主要作用,然后随机探索也具有一定意义,而视觉和空间记忆意义不大。     

外果皮厚度和种子大小对五种栎属橡子扩散的影响

动物对种子的扩散和贮藏是一个复杂的生态学过程,常常受到种子特征的影响。有关种子特征如何影响动物对种子扩散,许多研究结果并非完全一致。我们于2009 年9 月在黑龙江东方红林场野外和围栏内释放五种栎属橡子(Quercus mongolica,Q.serrata var. brevipetiolata,Q. aliena,Q.variabilis 和Q. liaotungensis),研究种子特征对鼠类(Apodemus peninsulae, Clethrionomys rufocanus 和Tamias sibiricus)扩散和埋藏橡子的影响。野外释放结果表明:橡子大小和外果皮厚度显著影响鼠类对橡子的扩散和埋藏。鼠类偏向扩散和埋藏种皮厚的大橡子,种皮薄的小橡子则多被原地取食。种皮厚的大橡子扩散距离显著高于种皮薄的小橡子。然而,只有外果皮的厚度显著影响围栏内花鼠对橡子的扩散和埋藏,橡子大小并非主要的影响因素。种子特征影响种子扩散的效应可能在种群和群落水平上存在差异。     

围栏条件下捕食风险对岩松鼠贮藏核桃种子行为的影响

面对捕食风险,贮藏植物种子的啮齿动物如何通过调整其贮藏行为,权衡捕食风险和贮食效益,需要深入研究。2006 年9 月,在北京东灵山地区,以黄鼬作为捕食风险源,在半自然围栏内比较了有无捕食风险源时,岩松鼠贮藏的核桃种子的状态,以及埋藏种子在实验围栏内的分布、微生境和搬运距离,以探讨捕食风险对岩松鼠贮藏种子行为的影响。结果表明,捕食风险源存在时,搬运和埋藏种子的比例都显著减少,弃置地表种子的比例无显著差异;埋藏于高风险区的种子比例减少,中风险区和低风险区的埋藏种子比例增加,但差异都不显著;位于裸地和草下的埋藏种子比例减少,位于墙基的埋藏种子比例增加,但差异都不显著;此外,埋藏种子的搬运距离也没有显著差异。可见,捕食风险源存在时,岩松鼠显著减少了搬运和埋藏种子的比例,但对埋藏种子时的埋藏区域和微生境选择,以及搬运距离无显著影响。差异不显著可能与围栏效应有关。     

种子大小对小泡巨鼠贮藏行为的影响

以小泡巨鼠为研究对象,在围栏条件下,测定小泡巨鼠对大小两种栓皮栎种子的贮藏行为差异,以检验最优贮藏空间模型的两个预测:(1)大种子(高价值食物)的贮藏率大于小种子(低价值食物);(2)大种子的贮藏距离远于小种子.结果表明:大种子的搬运比例(39%)多于小种子(21.5%),多数的小种子(53%)被取食,大种子的贮藏比率(16%)远大于小种子(7%),上述结果支持模型的预测(1).但是,不同大小种子在贮藏距离上没有显著差异,因而预测(2)没有被支持.实验结果表明种子价值对鼠类的取食和贮藏行为有十分重要的影响,但围栏空间可能影响对模型预测(2)的检验.     

Seed caching and cache pilferage by three rodent species in a temperate forest in the Xiaoxinganling Mountains

Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence, differentiation in cache pilfering abilities among sympatric rodents with different hoarding strategies is seldom addressed. We carried out semi-natural enclosure experiments to investigate seed hoarding tactics among three sympatric rodent species (Tamias sibiricus, Apodemus peninsulae and Clethrionomys rufocanus) and the relationship of their pilfering abilities at the inter- and intraspecific levels. Our results showed that T. sibiricus exhibited a relatively stronger pilfering ability than A. peninsulae and C. rufocanus, as indicated by its higher recovery rate of artificial caches. Meanwhile A. peninsulae showed a medium pilfering ability and C. rufocanus displayed the lowest ability. We also noted that both cache size and cache depth significantly affected cache recovery in all three species. T. sibiricus scatter-hoarded more seeds than it larder-hoarded, A. peninsulae larder-hoarded more than scatter-hoarded, and C. rufocanus acted as a pure larder-hoarder. In T. sibiricus, individuals with lower pilfering abilities tended to scatter hoard seeds, indicating an intraspecific variation in hoarding propensity. Collectively, these results indicated that sympatric rodent species seem to deploy different food hoarding tactics that allow their coexistence in the temperate forests, suggesting a strong connection between hoarding strategy and pilfering ability.     

Substrate type affects caching and pilferage of pine seeds by chipmunks

The abiotic environment often influences the ways in which animalsinteract. By affecting the cues associated with buried seeds,the type of substrate used by seed-caching rodents may alterthe relative probabilities of cache pilferage and cache retrieval.We predicted that, after a wildfire, the presence of ash wouldimpair rodents' ability to smell pine seeds on the forest floor.In a laboratory experiment, we compared the foraging success,caching frequency, and cache recovery of chipmunks (six Tamiasamoenus and six T. quadrimaculatus) in ash versus sand substrates.Initial results supported our hypothesis: chipmunks found only2.3% of 108 caches of Jeffrey pine (Pinus jeffreyi) seeds thatwe buried in ash but found 98% of caches in sand. However, chipmunksmade as many or more of their own caches in ash compared withsand (48% for T. amoenus, 73% for T. quadrimaculatus.) Whenforaging for seeds cached in ash by themselves and by otherindividuals, they found significantly higher proportions oftheir own caches (62%) than of caches made by others (25%).However, when foraging in sand, they found high proportionsboth of their own caches and those of others (86 versus 81%).These results suggest that olfaction is less effective in ashthan in sand, that spatial memory enables chipmunks to recovertheir own caches in ash, and that caching in ash may allow animalsto avoid pilferage of stored food. As chipmunks are importantdispersers of seeds, changes in their foraging patterns or competitiveinteractions after fire could significantly affect pine regeneration.     

The influence of environmental conditions on cache recovery and cache pilferage by yellow pine chipmunks (Tamias amoenus) and deer mice (Peromyscus maniculatus)

I conducted a field experiment in 10 x 10 m enclosures to explorehow seed and soil moisture levels influence the ability ofknowledgeable and naive rodents to find natural caches of Jeffreypine (Pinus jeffreyi) seeds. Subjects were yellow pine chipmunks(Tamias amoenus) and deer mice (Peromyscus maniculatus) searchingfor caches that they had made, caches made by other individualsof the same species, or caches made by individuals of the otherspecies. Subjects that made caches (knowledgeable subjects)relied on spatial memory to find many of their own caches during recovery sessions, and their ability to locate caches was notaffected by water content of seeds or soil. Naive subjectsfound few caches under dry conditions, but under wet conditions,they located as many caches as did the rodents that made them.Naive subjects apparently relied on olfaction to find caches,a sensory modality that works more effectively under moist conditions. Subjects had as much success foraging for caches made by membersof their own species as for caches made by the other species.I present a hypothesis that predicts how foragers could modifypredominately memory-based search to predominately olfactory-basedsearch as the weather changes from dry to wet. When foragersrely on spatial memory, those foragers find only their own caches, but when they can also use olfaction, they pilfer cachesmade by other individuals. Consequently, the nature of competitiveinteractions among members of the seed-caching guild may changeas the weather changes.     

Dispersal by rodent caching increases seed survival in multiple ways in canopy‐fire ecosystems

Seed‐caching rodents have long been seen as important actors in dispersal ecology. Here, we focus on the interactions with plants in a fire‐disturbance community, specifically Arctostaphylos species (Ericaceae) in California chaparral. Although mutualistic relationships between caching rodents and plants are well studied, little is known how this type of relationship functions in a disturbance‐driven system, and more specifically to systems shaped by fire disturbance. By burying seeds in the soil, rodents inadvertently improve the probability of seed surviving high temperatures produced by fire. We test two aspects of vertical dispersal, depth of seed and multiple seeds in caches as two important dimensions of rodent‐caching behavior. We used a laboratory experimental approach to test seed survival under different heating conditions and seed bank structures. Creating a synthetic soil seed bank and synthetic fire/heating in the laboratory allowed us to have control over surface heating, depth of seed in the soil, and seed cache size. We compared the viability of Arctostaphylos viscida seeds from different treatment groups determined by these factors and found that, as expected, seeds slightly deeper in the soil had substantial increased chances of survival during a heating event. A key result was that some seeds within a cache in shallow soil could survive fire even at a depth with a killing heat pulse compared to isolated seeds; temperature measurements indicated lower temperatures immediately below caches compared to the same depth in adjacent soil. These results suggest seed caching by rodents increases seed survival during fire events in two ways, that caches disrupt heat flow or that caches are buried below the heat pulse kill zone. The context of natural disturbance drives the significance of this mutualism and further expands theory regarding mutualisms into the domain of disturbance‐driven systems.     

Effects of habitat and season on removal and hoarding of seeds of wild apricot (Prunus armeniaca) by small rodents

The wild apricot (Prunus armeniaca) is widely distributed in the Donglingshan Mountains of Mentougou District of Beijing, China, where its seeds may be an important food resource for rodents. Predation, removal and hoarding of seeds by rodents will inevitably affect the spatio-temporal pattern of seed fate of wild apricot in this area. By marking and releasing tagged seeds of wild apricot, we investigated seeds survival, scatter-hoarding, cache size and seedling establishment, and the preference of micro-habitats used by rodents to store seeds. The results showed that: (1) rodents in this area hoarded food intensively in autumn, as well as in spring and summer. (2) There were significant effects of habitat and season on removal rate of tagged seeds at releasing plots. In both two types of habitats, Low and High shrub, tagged seeds were removed most rapidly by rodents in autumn, at intermediate rates in spring and least rapidly in summer. (3) During three seasons, mean dispersal distance of scatter-hoarded seeds in Low shrub habitat was greater than that in High shrub. Most removed seeds were buried within 21.0 m of the releasing plots. (4) In both two types of habitats, Low and High shrub, rodents tended to carry seeds to US (Under shrub) and SE (Shrub edge) microhabitats for scatter-hoarding or predation. (5) Among the caches made by rodents, most caches contained only one seed, but up to three seeds were observed; caches of 2–3 seeds were common in autumn. (6) By comparing dental marks, we determined that large field mice (Apodemus peninsulae) and David’s rock squirrels (Sciurotamias davidianus) contributed to removal and predation of released tagged seeds. However, only the large field mice exerted a pivotal and positive role on the burial of dispersed seeds. (7) Establishment of three seedlings originated from seeds buried by rodents was documented in High shrub habitat.     

贮藏种子的啮齿动物对油茶种子沉积形式的影响

种子沉积的质量常常涉及种子扩散作用者(如鸟类和小型啮齿动物)对生境和微生境的选择以及种子沉积的形式(如种子埋藏).然而,很少的研究涉及到种子在离开母树后被这些动物沉积在何处.在四川省都江堰一个实验林场的2个林分(次生林和原生林)内,通过追踪用带编号的金属薄片标记的油茶(Camellia oleifera Abel.)种子的命运,研究了贮藏种子的啮齿动物对种子沉积的影响.研究发现:在2个林分内,80%以上的种子被很好地埋藏在0～60 mm深的土壤中,而小部分种子则被放置在地表(但有少量落叶遮盖).小型啮齿动物喜好在灌丛下或灌丛边缘贮藏和取食种子,可能是在这样的微生境下它们在觅食时将遭遇较小的捕食风险.研究还发现,贮藏点的微生境分布随贮藏点等级而逐渐变化:在两个林分内较高等级的贮藏点(如次贮藏点和三级贮藏点)比初级贮藏点有更多的种子被贮藏在灌丛下或灌丛边缘.这表明,啮齿动物对油茶种子的埋藏可能更有益于种子的存活、萌发以及幼苗的建成.啮齿动物将散落在母树下或其附近的油茶种子扩散到不同的微生境,这可能有利于他们遭遇到更多的适宜环境而萌发,实现幼苗补充.     

贮藏种子的啮齿动物对油茶种子沉积形式的影响

种子沉积的质量常常涉及种子扩散作用者(如鸟类和小型啮齿动物)对生境和微生境的选择以及种子沉积的形式(如种子埋藏)。然而,很少的研究涉及到种子在离开母树后被这些动物沉积在何处。在四川省都江堰一个实验林场的2个林分(次生林和原生林)内,通过追踪用带编号的金属薄片标记的油茶(CamelliaoleiferaAbel.)种子的命运,研究了贮藏种子的啮齿动物对种子沉积的影响。研究发现在2个林分内,80%以上的种子被很好地埋藏在0~60mm深的土壤中,而小部分种子则被放置在地表(但有少量落叶遮盖)。小型啮齿动物喜好在灌丛下或灌丛边缘贮藏和取食种子,可能是在这样的微生境下它们在觅食时将遭遇较小的捕食风险。研究还发现,贮藏点的微生境分布随贮藏点等级而逐渐变化在两个林分内较高等级的贮藏点(如次贮藏点和三级贮藏点)比初级贮藏点有更多的种子被贮藏在灌丛下或灌丛边缘。这表明,啮齿动物对油茶种子的埋藏可能更有益于种子的存活、萌发以及幼苗的建成。啮齿动物将散落在母树下或其附近的油茶种子扩散到不同的微生境,这可能有利于他们遭遇到更多的适宜环境而萌发,实现幼苗补充。     

啮齿类对植物种子的传播作用

种子植物是固着生活的有机体 ,如果能成功地将种子扩散到适宜的生境 ,将会在生存竞争中获得优势。在长期的进化过程中 ,不同的植物依赖不同的媒介传播种子 ,如风传播 ,水传播 ,或自身的力量传播 (重力、弹爆力等 )。在很多情况下也依靠动物完成种子扩散 ,即所谓的动物传播。根据依赖的动物对象不同可以分为蚁传播 ,鸟传播 ,哺乳类传播 ,以及鱼传播 ,爬行类传播等。哺乳类中传播种子的类群主要包括翼手类 ,灵长类和啮齿类。由于能够飞行 ,热带食果实的蝙蝠(属翼手类 )对种子的传播作用最明显 ,研究得也最多 ,源于蝙蝠类的传播特称为ｃｈｉｒ…