动物搬运与地表覆盖物对辽东栎种子命运的影响

东灵山的辽东栎成熟林内尽管每年有大量种了散落,但实生苗极少,种群天然更新主要依赖于萌蘖。为确定影响种子命运和种子库动态的主要因素,调查统计了不同试验条件下的种子命运。结果发现：（１）动物搬运和取食是影响种子命运和种子库动态的主要因素,在没有该因素的影响下,辽东栎能够完成从种子到幼苗的过程。（３）被啮齿动物贮藏的种子大多被取食,极少存活;（３）地表覆盖物能养活动物搬运、取食的影响,但尚不足导以致新生幼苗出现。     

东灵山辽东栎虫损种子调查

2000年8月底至9月底,在北京东灵山地区小龙门林场对2块辽东栎样地中虫损种子下落动态进行了调查.结果表明:2块样地辽东栎种子产量分别高达19.15和91.23颗·m-2,而2块样地虫损种子较多,分别为49.23和33.38个·m-2,所占种子库比例分别为36.93%和25.96%;1999年研究发现(阎文杰,2000),2样地辽东栎种子产量为13.09和7.24颗·m-2,其中虫损种子产量为10.87和5.90颗·m-2,虫损率高达82.22%和75.43%.2年的观察结果均证实虫损种子在种子雨早期迅速下落,且低产年份的虫损种子在种子库中的比例显著高于高产年份.高比例的虫损种子可能是导致辽东栎实生苗更新率低的重要因素.     

东灵山地区辽东栎种子库统计

东灵山地区辽东栎成熟林内辽东栎（Ｑｕｅｒｃｕｓ ｌｉａｏｔｕｎｇｅｎｓｉｓ）种群更新记要依赖于萌蘖,而实生苗极少。为探索其原因,我们应用随机样方法进行了辽东栎种子库统计。结果表明：１）种子雨持续时间短、强度大,种子散落总密度为１２３个．ｍ＾－２。２）种子大小在种子雨的不同时期差异很大,大的种子在种子雨高峰中后期所占比例较高。３）土壤种子库存在时间约１００ｄ左右,种子密度最高时为４２．７个．ｍ＾－２     

昆虫与栎树的相互关系及其对栎林更新的影响

本文概述了昆虫和栎树的相互关系以及栎林种群更新研究的进展,从叶片和栎实两个方面分别分析昆虫对栎树的危害、栎树对昆虫的防御以及栎林种群更新中的问题等。（1）危害栎树的昆虫种类丰富,它们以取食叶片和栎实为主,昆虫的寄生几乎使栎实完全失去活力。（2）栎树的防御效应能影响昆虫啃食叶片的程度,被昆早寄生的栎实提前下落以及栎实产量周期性的大小年变化,能降低昆虫寄生和取食栎实所带来的损失。（3）昆虫啃食叶片降低栎树的能量利用和营养物质贮存,昆虫对栎实的寄生和取食给栎树的种子库及苗库带来压力,直接影响到栎林的种群更新,此外,昆虫对栎实的寄生也会影响脊椎动物搬运栎实时的选择取向,间接控制栎实扩散,进而影响栎树的种群更新。     

辽东栎叶片昆虫取食形状多样性及其变化模式

取食辽东栎(Quercus liaotungensis)叶片的植食性昆虫有丰富的多样性和重要的生态功能,昆虫取食叶片留下的形状变化多,易观察,可以作为昆虫物种多样性监测的手段之一。研究北京西部东灵山地区辽东栎叶片被植食性昆虫取食状况,发现昆虫对辽东栎叶片的危害非常普遍,叶片被食频率约为90％,被食面积约5％,取食状可分为9类,其中以缘食和孔食为主,共记录20余种植性昆虫,其中蛾类幼虫和甲虫是主要取食种类,植食性昆虫集中出现在叶片发育的早期阶段（5－6月份）,7月份后,大多数幼虫发育成熟,取食叶片的面积减少。各取食状所涉及昆虫种类的组成不同,面积呈不同的季节变化模式,其中缘食状和孔食状之间有显著的正相关关系;辽东栎叶片在展叶初的叶面积最低,在7月底均达到最大值,然后呈下降趋势,单位面积重量也在展叶初最低,在6月底接近最大值,不同坡向的辽东栎林和叶片面积,单位面积重量及叶片被食面积均有显著差异,偏阳坡（东南坡） 高于偏阴坡（西北坡）。以上结果表明,辽东栎叶片维持了昆虫物种多样性,昆虫的生长发育与辽东栎的物候规律相互协调,昆虫种类的取食呈季节和空间变化。     

秦岭南坡短柄枹栎和锐齿槲栎的种子产量和种子大小及其与昆虫寄生的关系

【目的】为了解昆虫寄生特征与短柄枹栎 Quercus glandulifera 和锐齿槲栎 Quercus aliena var. acuteserrata 的种子产量及种子大小的关系。【方法】本研究于2011和2012年在秦岭南坡佛坪国家自然保护区,对短柄枹栎和锐齿槲栎种群的种子产量和昆虫寄生特征进行了野外调查研究。【结果】2年中短柄枹栎、锐齿槲栎种子雨密度和种子产量均差异明显,2011年短柄枹栎种子雨密度和种子产量分别为145.76±24.56粒/m²和74.97±11.56粒/m²,分别显著高于2012年的64.09±9.61粒/m²和34.30±3.51粒/m²;2011年锐齿槲栎种子雨密度和种子产量分别为238.88±43.97粒/m²和117.34±18.76粒/m²,分别显著高于2012年的112.00±19.20粒/m²和55.96±19.20粒/m²。2011年短柄枹栎和锐齿槲栎的种子产量中完好种子所占比例分别为49.73%和50.73%,分别显著高于2012年的38.69%和44.28%;而2011年虫蛀短柄枹栎和锐齿槲栎种子所占比例分别为28.05%和19.31%,分别低于2012年的39.77%和26.63%,但并无显著差异。2011和2012年,短柄枹栎和锐齿槲栎虫蛀种子个体均显著大于完好种子,且2011年二者虫蛀种子所含幼虫数与种子大小的相关性显著,2012年二者相关性不显著。【结论】短柄枹栎和锐齿槲栎种子的虫蛀率与种子产量有一定的关系,即在种子产量较低年份,虫蛀率有升高趋势,反之有降低趋势。同时,昆虫对这两种栎树种子中个体大的种子有寄生选择偏好,同时虫蛀种子所含幼虫数与种子大小也有一定的关系,即种子越大,所含昆虫幼虫数就越多。     

昆虫寄生对栓皮栎坚果特征和萌发行为的影响

有多种昆虫常寄生于栎属植物的坚果中, 进而影响种子的质量、 萌发、 幼苗建成等植物的更新过程。为探讨昆虫寄生与上述过程之间的关系, 本研究于2007年和2008年在太行山济源地区调查了昆虫对栓皮栎Quercus variabilis坚果的寄生情况, 同时探讨了昆虫寄生对坚果单宁水平、 萌发和幼苗生长的影响; 并于2007年9月, 分别将完好的和昆虫寄生的栓皮栎坚果种植于土壤4 cm深处, 对坚果萌发情况、 幼苗出土时间、 叶片数量和生物量等进行了对比分析。结果表明: 1）2007年栓皮栎坚果的虫寄生率为30.04%, 显著低于2008年（47.68%）, 表现出年际变化; 2）虫寄生坚果中单宁酸含量（11.54%±1.36%）显著高于完好坚果（7.36%±1.31%）（P=0.004）; 3）虫寄生坚果的鲜重、 直径、 长度均小于完好坚果; 4）虫寄生坚果的霉烂率（28%）和不完全萌发率（28%）均高于完好坚果（霉烂率0%, 不完全萌发率2%）; 但虫寄生坚果幼苗建成率（56%）低于完好坚果（92%）; 虫寄生坚果幼苗出土持续时间（埋藏后35周）短于完好坚果（埋藏后37周）; 5）在坚果埋藏和幼苗萌出当年的冬季, 由虫寄生坚果和完好坚果建成的幼苗的高度、 叶片数间均无显著差异, 但在翌年的生长季节, 两项指标均出现显著性差异; 6）经过一个完整的生长周期（1年）之后, 由虫寄生坚果所建成幼苗的根长、 根重量和生物量3项指标显著低于完好坚果, 而叶片数、 茎长、 叶重和茎重指标在二者间无显著性差异。研究结果提示, 昆虫寄生会对栎类坚果的种子质量和萌发行为产生一定的影响, 这可能是栎类植物群落更新的适应性选择。     

昆虫种子捕食与蒙古栎种子产量和种子大小的关系

为了了解昆虫种子捕食者在栎类种群更新中的作用,于2006年秋季,在黑龙江省伊春市带岭区东方红林场研究了昆虫对蒙古栎Quercus mongolica在参园和东山两个种群的种子蛀食情况及其与蒙古栎种子产量和种子大小的关系。结果表明：(1)在参园和东山两个林分内,蒙古栎种子雨动态非常相似,种子雨成分中完好种子的平均密度仅为3.2±4.1个/m²（参园）和1.7±2.8个/m²（东山）,分别仅占种子产量的4.0％和3.2％,而虫蛀种子和败育种子的比例均在38%以上,以虫蛀种子的比例最高,分别为58.2％和57.7％;(2)柞栎象Curculio arakawai是蛀食蒙古栎种子的主要昆虫种类,在虫蛀种子中所占比例高达96.8％（参园）和97.1％（东山）,且象甲蛀食种子中所含虫卵数与种子大小有关,即种子越大,所含象甲的虫卵数就较多。本研究的结果说明2006年蒙古栎成熟种子多遭遇虫蛀,导致完好种子的数量极低,因而可能成为限制蒙古栎种群更新的重要因素。     

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%)。     

秦岭中段不同坡向锐齿栎种子雨、土壤种子库与幼苗更新

以秦岭中段不同坡向(阳坡、半阳坡、半阴坡及阴坡)锐齿栎天然林为对象,对锐齿栎种子雨、种子库的数量、质量动态以及幼苗发育过程进行研究.结果表明: 锐齿栎种子雨一般从8月中旬开始,9月中下旬到10月上旬达到高峰期,11月中上旬结束;不同坡向的种子雨降落历程、发生时间和组成不同;半阳坡种子雨强度最大,为134.13粒·m^-2,其余大小依次为阳坡、半阴坡、阴坡;阳坡种子雨降落时间最早、持续时间最长,高峰期持续时间也最长,阴坡种子雨降落时间最晚、持续时间最短,高峰期持续时间也最短;种子活力及成熟种子占其种子雨的比例大小顺序为半阳坡>阳坡>半阴坡>阴坡.从种子雨降落结束到翌年8月,各坡向土壤种子库总储量大小顺序均为半阳坡>阳坡>半阴坡>阴坡;各坡向的土壤种子库中成熟、未成熟、被啃食种子数量和种子活力均随时间变化呈递减趋势,而霉烂种子数量增加;各坡向土壤种子库中的种子均主要集中在枯落物层,其次为0~2 cm土层,而在2~5 cm土层中只有极少量种子存在.4种坡向中锐齿栎幼苗的密度差异显著,半阳坡幼苗最多,其余依次是阳坡、半阴坡和阴坡.半阳坡更适合锐齿栎种子的萌发和幼苗生长.     

槲栎超寄生橡子内象甲幼虫的适应对策

栎属植物的橡子常常受到象甲的侵害, 对橡子存活产生影响, 但有关橡子对象甲幼虫适合度影响的研究尚未见报道。本研究旨在通过对槲栎Quercus aliena种子雨进程以及象甲幼虫逃逸过程的调查, 研究二者之间的进化适应关系。结果表明： 当年槲栎的种子产量为51.92±29.26粒/m², 虫蛀率达到42.4%。虫蛀的橡子中65%以上被象甲超寄生, 且显著大于完好的橡子。在种子下落过程中, 早期从橡子中逃逸的象甲幼虫要比后期逃逸的大。对某一超寄生的橡子而言, 首先逃逸出的象甲幼虫要比随后逃逸的幼虫大。另外, 从早期脱落的橡子中逃逸的幼虫明显小于后期脱落的橡子。象甲幼虫的干重随着橡子内象甲幼虫数量的增加而显著下降。象甲幼虫寄生数量与橡子的长径和短径呈现明显的正相关关系。尽管超寄生降低了象甲虫的适合度, 但雌性成体象甲产卵过程中偏好选择大橡子在一定程度上可以减少这种不利影响。因此, 小橡子可能更容易逃脱象甲的超寄生而获得较大的存活机会。     

Prolonged diapause and seed predation by the acorn weevil,Curculio robustus,in relation to masting of the deciduous oak Quercus acutissima

Many researchers have studied the relationship between masting by trees and seed predation by insects. Most of these studies have been plant centered, with little focus on the insect perspective. To estimate the effect of mast seeding on insect seed predators, the life‐history traits of these insects must also be considered because some seed insects can survive lean years by prolonged diapause. In this study, I examined larval infestation of acorns and life‐history traits of the acorn weevil, Curculio robustus (Roelofs) (Coleoptera: Curculionidae), in relation to acorn production of the deciduous oak Quercus acutissima Carruthers (Fagaceae) in a coppice stand in central Japan in 2004–2009. Curculio robustus females oviposit into Q. acutissima acorns, inside which the larvae develop. Mature larvae leave acorns and burrow into the soil, where they overwinter. Although germination did occur in acorns infested by weevil larvae, the percentage of germination was lower in acorns damaged by many larvae. Acorn production in Q. acutissima varied considerably among years. Both the number of C. robustus larvae infesting acorns and the percentage of acorns infested were affected by the amount of acorns produced by Q. acutissima, and two successive lean years appeared to have a considerable impact on C. robustus population size. Consequently, only a small fraction of the acorns produced were lost to predation in a mast year after two successive lean years. However, C. robustus could survive the two successive lean years because of prolonged larval diapause, probably leading to a marked decrease in population size. These findings suggest that masting in Q. acutissima succeeds as a predator satiation strategy in response to acorn damage by C. robustus, and that C. robustus has developed prolonged diapause as a counter‐adaptation.     

Spatial and temporal variations in insect-infested acorn fall in a <Emphasis Type="Italic">Quercus liaotungensis</Emphasis> forest in North China

Three plots with different aspects and slope characteristics were surveyed in 1999 and 2000 to clarify the spatial and temporal variations in insect-infested acorn fall patterns in a Quercus liaotungensis Koidz. forest in the Dongling Mountain region, North China. There was a significant difference in the proportion of infested acorns in the three plots in a low crop year, but not in a mast year. Within oakwoods on the southeast-facing slope, the insect infestation rate on the upper slope was significantly higher than on the lower slope, but not in the northwest-facing plot. Infestation rate in the low crop year in all three plots was significantly higher than infestation in the mast year. Most of the early fallen acorns had a higher proportion of insect infestation, and in the mast year it was much more obvious than in the low crop year. The proportion of infested acorns in seed bank along the topographic gradient showed a similar decreasing trend with acorn fall time, but the proportion on the upper slope was the highest and the proportion on the lower slope was the lowest. Larval emergence from acorns commenced just after acorns fell from the trees and lasted for 40–50days, with peak emergence occurring from 24 to 32days after acorn rain began. We conclude that insect-infested acorn distribution in Q.liaotungensis shows spatial and temporal heterogeneity, and an early drop of infested acorns can be a short-term defensive strategy against insect infestation.     

槲栎种子雨进程中昆虫的捕食特征

为了了解昆虫捕食与槲栎Quercus aliena种子大小和产量的关系以及在栎林更新中的作用,于2008和2009年秋季,分别在暖温带伏牛山系天池山国家森林公园内研究了两个年度槲栎的种子雨过程及昆虫捕食特征。结果表明：（1）种子雨过程从8月中下旬到9月底约经历40 d,存在高峰期且时段较明显,高峰期下落种子量分别占全部种子雨量的78.13%（2008年）和75.91%（2009年）;（2）槲栎的种子雨强度年间存在较大差异,2008年明显小于2009年（两年分别为31.75±16.65粒/m²和51.92±29.26粒/m²）,但2009年的橡子明显比2008年小（两年分别为1.94±0.61 cm³和2.46±0.57 cm³）;（3）种子雨构成比例在两个年份间存在差异,完好种子的量分别为59.05%（2008年）和36.12%（2009年）,虫蛀率在大量结实的2009年显著提高;（4）虫蛀橡子（2.29±0.42 cm³）显著大于完整橡子（1.59±0.32 cm³）,且虫蛀种子中所含虫卵数与种子大小显著正相关,昆虫有选择大种子产卵寄生的偏好。本研究的结果说明,昆虫对槲栎大种子有寄生选择偏好;大部分槲栎种子遭遇象甲虫蛀而降低生命活力,这可能是影响槲栎林更新的主要因素之一。     

都江堰地区灌丛内袍栎橡子的捕食和搬运

从2000年9月至2002年12月,以四川都江堰常绿阔叶林灌丛内的优势种--枹栎(Quercus serrata)为研究对象,研究了昆虫、鼠类和真菌对枹栎橡子的捕食和搬运.结果表明(1)取食橡子的鼠类的群落结构和数量在年间差异较小,这可能与三年间袍栎橡子的产量相对稳定有关;(2)袍栎橡子的虫蛀率在三年间存在显著性差异,范围在14.17%-32.49%之间;(3)鼠类的就地取食和搬运是影响种子库内橡子命运的主要因素;(4)橡子虫蛀率的变化影响鼠类的觅食活动.鼠类对饱满橡子和虫蛀橡子的选择性取食和搬运可能影响许多坚果植物(栎树)的自然更新过程[动物学报50(4)535-540,2004].     

都江堰地区灌丛内迺栎橡子的捕食和搬运(英文)

从 2 0 0 0年 9月至 2 0 0 2年 1 2月 ,以四川都江堰常绿阔叶林灌丛内的优势种———栎 (Quercusserrata)为研究对象 ,研究了昆虫、鼠类和真菌对栎橡子的捕食和搬运。结果表明 :(1 )取食橡子的鼠类的群落结构和数量在年间差异较小 ,这可能与三年间栎橡子的产量相对稳定有关 ;(2 )栎橡子的虫蛀率在三年间存在显著性差异 ,范围在 1 4 1 7% - 32 4 9%之间 ;(3)鼠类的就地取食和搬运是影响种子库内橡子命运的主要因素 ;(4 )橡子虫蛀率的变化影响鼠类的觅食活动。鼠类对饱满橡子和虫蛀橡子的选择性取食和搬运可能影响许多坚果植物 (栎树 )的自然更新过程     

Seed growth suppression constrains the growth of seed parasites: premature acorn abscission reduces Curculio elephas larval size

Abstract.  1. The abscission of seeds infested by insects is common in many plants and has been proposed as a defensive mechanism, although its negative consequences for insects have rarely been assessed.
2. We assessed the consequences of seed abscission studying the interactions between the holm oak Quercus ilex and the chestnut weevil Curculio elephas , its main pre-dispersal seed predator. Female weevils oviposit into the acorns and the larvae must complete their development inside a single acorn feeding on the cotyledons. The growth of the infested acorns is suppressed because they are prematurely abscised.
3. Female weevils oviposit along the acorn growing period; hence, the size of the infested acorns increased with date. The growth of the larvae inside the smaller, early infested, acorns was constrained because food (i.e. cotyledons) was frequently depleted. Larval size increased with the date along with the size of the infested acorns, but it declined slightly in the latest dates as a result of the higher conspecific competition provoked by the larger number of larvae per acorn.
4. The present results demonstrate that premature seed abscission by Q. ilex had negative consequences for C. elephas , as a smaller acorn size reduced food availability and constrained larval size, a key insect life history trait. At the same time, it is suggested that the growth suppression of infested acorns may condition the oviposition phenology of these insects according to their body size. These results need to be considered in further research in the context of the evolutionary significance of premature seed abscission as a defensive mechanism.     

Acorn crop size and pre-dispersal predation determine inter-specific differences in the recruitment of co-occurring oaks

The contribution of pre-dispersal seed predation to inter-specific differences in recruitment remains elusive. In species with no resistance mechanisms, differences in pre-dispersal predation may arise from differences in seed abundance (plant satiation) or in the ability of seeds to survive insect infestation (seed satiation). This study aimed to analyse the impact of pre-dispersal acorn predation by weevils in two co-occurring Mediterranean oaks (Quercus ilex and Quercus humilis) and to compare its relevance with other processes involved in recruitment. We monitored the patterns of acorn production and acorn infestation by weevils and we conducted experimental tests of acorn germination after weevil infestation, post-dispersal predation and seedling establishment in mixed forests. Monitoring and experimental data were integrated in a simulation model to test for the effects of pre-dispersal predation in recruitment. In both oaks pre-dispersal acorn infestation decreased with increasing acorn crop size (plant satiation). This benefited Q. ilex which exhibited stronger masting behaviour than Q. humilis, with almost a single and outstanding reproductive event in 6 years. Acorn infestation was more than twice as high in Q. humilis (47.0%) as in Q. ilex (20.0%) irrespective of the number of seeds produced by each species. Although germination of infested acorns (seed satiation) was higher in Q. humilis (60%) than in Q. ilex (21%), this could barely mitigate the higher infestation rate in the former species, to reduce seed loss. Conversely to pre-dispersal predation, no inter-specific differences were observed either in post-dispersal predation or seedling establishment. Our results indicate that pre-dispersal predation may contribute to differences in seed supply, and ultimately in recruitment, between co-existing oaks. Moreover, they suggest that seed satiation can barely offset differences in seed infestation rates. This serves as a warning against overemphasising seed satiation as a mechanism to overcome seed predation by insects. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Acorn Pericarp Removal as a Cache Management Strategy of the Siberian Chipmunk,Tamias sibiricus

Numerous recent studies have revealed a variety of behavioral adaptations of rodents for maximizing returns from cached seeds. Herein we report on a novel behavior by the Siberian chipmunk (Tamias sibiricus) in northeastern China, by which they consistently remove the pericarp (shell) of Quercus mongolica acorns before dispersing and caching these nuts. We investigated the effects of pericarp removal on acorn germination, tannin concentrations, cache pilferage, and insect damage, to determine if and how pericarp removal facilitates cache management by Siberian chipmunks and whether or not such behavior influences seed fates. Chipmunks cached acorns only after the pericarps were removed. Chipmunks preferred pericarp‐removed acorns over intact acorns when removing them from seed stations for both consumption and caching. Pericarp removal did not affect germination or tannin concentration of cached Q. mongolica acorns, suggesting that the behavior is not an adaptation for long‐term storage and tannin decomposition. Acetone treatments of the pericarp and artificial pericarp removal failed to alter pilferage rates by Siberian chipmunks and wood mice (Apodemus peninsulae). Since damage of acorns by weevils often leads to cache losses, we also tested the effects of weevil infestation on cache decision following pericarp removal. Siberian chipmunks removed pericarps and then scatter hoarded significantly more sound than weevil‐infested acorns, strongly suggesting that pericarp removal is used to discriminate between the infested and non‐infested acorns. Thus, we argue that the primary function of this behavior is to ensure successful storage of sound acorns, at least for short‐term storage. Future studies should consider the potential impact of pericarp removal on weevil populations and long‐term patterns of seed survival and establishment from the Siberian chipmunk’s caches.