【作者】 戎可；

【导师】 马建章；

【作者基本信息】 东北林业大学 ， 野生动植物保护与利用， 2009， 博士

【摘要】 2007年4月至2009年3月在黑龙江省凉水国家级自然保护区的阔叶红松林生态系统中,对松鼠越冬生存策略及其对红松天然更新的影响进行了系统研究,内容包括松鼠的生境选择、种群分布、贮食、重取行为、冬季行为节律及家域利用等。基于资源“利用-可利用性”不对称假设,采用样带法结合定位观察的方法调查松鼠的巢址偏好特征。采用主成分分析和Bailey’方法分析表明:1)松鼠选择比较高大且与周围树木联接比较多的针叶树作为巢树;2)尽管红松是研究地的优势树种,但松鼠更倾向于选择比红松枝叶更为浓密的云、冷杉树作为巢树。冬季对松鼠的无线电跟踪观察也证实,松鼠冬季多利用云、冷杉树上的巢。不论巢树是否位于红松母树林中,松鼠倾向于选择以云、冷杉为优势树种的小生境营巢,这样的生境位于红松母树林林隙,其乔木密度和多样性高于对照样方。采用固定样带定期调查的方法研究松鼠种群分布与秋冬季种群动态。结果显示:红松林和附近的云、冷杉林中都有松鼠分布并在其中越冬。红松林中的松鼠密度高于云、冷杉林1-2倍,但红松林中的的松鼠种群波动也大于云、冷杉林中松鼠种群。越冬期间云、冷杉林中的松鼠种群密度基本稳定,而红松林中松鼠种群死亡率高达70%左右,被捕食是主要原因。对松鼠的活捕调查结果表明,云、冷杉林中的松鼠个体多为亚成体,体重也要小于红松林中的个体,提示高等级序位的个体占据了拥有优质食物资源的红松母树林,而低等级序位的个体则分布于红松林外不同大小的其它针叶林中。对松鼠的无线电跟踪观察表明,即便是分布在红松林外的个体,在贮食期仍会进入红松母树林采集松塔,并将松子拖带回家域贮藏。采用固定样地定位观察法、基于无线电跟踪的目标动物观察法、固定样带扫描取样观察法、固定样带分期调查松鼠丢弃塔核等方法对松鼠的贮食行为和对松塔的选择性进行研究。结果显示:松鼠的贮食期自9月开始至11月结束,长达8-10周。贮食期的开始受松塔的成熟程度和其它动物(特别是人)对松塔的采集情况影响。由于能提供更高的能量回报,松鼠倾向于选择比较大的松塔进行贮藏。松鼠的贮食过程可以分为搜寻、松塔处理、松塔拖带与松子贮藏几个部分。贮食过程中松鼠以向着巢树方向拖带松塔的方式携带松子,松塔通常在拖带前被剥去了鳞片。每个松塔平均被依次拖至3棵大树的基部,松子被分批贮藏在这些树的周围。贮藏每批松子时,松鼠从松塔上取下8粒左右的松子建立3-4个贮点,每个贮点2-3个松子。2008年整个贮食期每只松鼠平均贮藏约337个松塔。分布在红松母树林内的松鼠的贮藏量高于母树林外松鼠近1倍。采用固定样带分期调查松鼠丢弃塔核结合样方法对松鼠的贮食生境进行了研究。主成分分析结果显示:种源距离、林型、红松幼苗数量、灌丛密度和类型是影响松鼠贮食生境选择的主要环境因子。松鼠贮食时对以云、冷杉林为优势树种的生境具有选择倾向性。50%以上的塔核被丢弃在距离母树300m以内的红松林林缘和红松林林隙中,表明松鼠可以将松塔携带出红松母树林。与无线电跟踪观察的结果相一致,红松林外150-600m的种源距离对松鼠的贮食生境选择没有影响。贮食样方内的红松幼苗数量显著高于对照样方,说明松鼠的贮食生境适于红松更新苗的建成。无线电跟踪观察结果表明,红松林外的松鼠在拖带松塔过程中随时会贮藏松子,其中约15%的松子贮藏在冬季家域以外的范围,但大部分松子被分散贮藏在距离巢树50m左右的贮食区里。贮食区直径平均约40m。贮食区样方的乔木、灌木密度和郁闭度均低于巢树样方。采用基于无线电跟踪的目标动物法和固定样地重取贮点调查法研究松鼠的冬季行为节律和重取行为,结果显示:松鼠冬季的活动节律为单峰型,随着气温的下降显著延后出巢时间,缩短活动时长。松鼠冬季家域近似椭圆形,大小为2.55±0.04hm~2,未见个体间家域重叠。每只松鼠家域范围内有多个巢和贮食区,依据巢和贮食区的位置特征及其利用率可将家域划分为3个部分:主区位于家域的中段,2个辅区位于主区两侧。贮藏的红松种子是松鼠冬季唯一的食物来源,平均每天取食量为30.7±0.4粒松子,整个冬季取食约4500粒松子,大致相当于45个松塔。在冬季的不同时段,松鼠对不同贮食区的利用率显著不同,位于主区的贮食区是松鼠的主要贮食区。随着时间推移空取率显著提高的现象提示松鼠很可能依靠空间记忆取回贮藏的食物。松鼠冬季通常每天轮换使用不同的巢,轮换利用多个巢有助于降低松鼠被天敌捕食的风险。贮食区的利用与巢的利用显著相关,松鼠通常取食后即直接进入就近的巢过夜,有助于松鼠减少能量损耗。区域分散贮食与多域集中重取及相应的巢轮换策略是松鼠对冬季低温环境、盗取压力及天敌捕食压力的综合响应。基于上述结果,松鼠对红松天然更新的贡献表现在:1.对种子库的贡献松鼠贮食红松种子对红松更新种子库的贡献表现在以下三个方面:(1)重取剩余在结实大年的2008年,松鼠的贮食量是其冬季松子消耗量的6-12倍,大部分的松子并没有被松鼠在冬季食用;(2)贮食遗留松鼠冬季死亡率很高,松鼠死亡后遗留下大量的松子贮点;(3)域外贮食无论分布在哪种林型,无论距离母树林远近,松鼠贮食时都会将部分松子贮藏在冬季家域范围以外;上述三部分松子如果能够逃过其它动物的取食便会进入天然更新的种子库。2.对种子的传播范围基于松鼠贮食的定向性和区域性,松鼠的分布决定了松鼠对红松种子的传播范围和方向。在种群尺度上,母树林林隙和距离母树林100-300m范围内的其它针叶林中是松鼠贮食密度最高的范围。这与松鼠的种群分布和家域结构是相一致的。松鼠对红松种子贮食传播的范围包括:红松林林隙、林缘以及有松鼠分布的针叶混交林、针阔混交林内和林缘。阔叶林特别是龄级比较小的阔叶林中的红松更新与松鼠的贮食传播没有直接的关系。更多还原

【Abstract】 This paper made a scientific research on behavior ecology of Eurasian red squirrels’ overwintering and its effect on natural regeneration of Korean pine in broad-leaved Korean pine mixed forest in Liangshui Nature Reserve since April 2007 to March 2009.Research contents included habitat selection,population distribution,hoarding-retrieving behavior,overwintering behavioral rhythm as well as home range use of Eurasian red squirrels.Based on“use-availability disproportion”hypothesis,the habitat preference of Eurasian red squirrels’ nest-site was studied by transects method and locating observation.Data sets were analyzed by principal component analysis and Bailey’ method.Results showed that(1)Eurasian red squirrels chose coniferous trees as nest trees which were higher and more approachable to surrounding trees.(2)Though Korean pine was the dominant species in study area,Eurasian red squirrels preferred fir and spruce as nest trees whose branches were more flourishing to Korean pine. Radio-tracing results also confirmed that Eurasian red squirrels used the nests on fir and spruce more frequently in winter.No matter whether the nest trees were in Korean pine forest or not,Eurasian red squirrels preferred to set nests in gap of Korean pine forest where fir and spruce were in dominance and the density and diversity of trees were higher than control samples.Fixed transects method was used to make a regular investigation of the distribution and dynamic of population of Eurasian squirrels in autumn and winter.Results demonstrated that Eurasian red squirrels distributed and overwintered not only in Korean pine forest,but also in nearby fir and spruce forest.The number of Eurasian red squirrels in Korean pine forest was 1-2 times as that in fir and spruce forest.The population density of Eurasian red squirrels in fir and spruce forest was more invariable than that in Korean pine forest.Seventy percent of Eurasian red squirrels in Korean pine forest were dead while overwintering mainly because of being preyed on. Alive-catching results manifested that sub-adults of Eurasian red squirrels with lighter body weight as subordinate individuals usually settled in fir and spruce forest as well as other various forests while the adults as dominant individuals dominated in Korean pine forest where they had quality source of food.However,radio-tracing results revealed that Eurasian red squirrels who settled out of Korean pine forest still entered Korean pine forest collected cones and then took them back home range during hoarding period.The hoarding behavior and cone selection of Eurasian red squirrels were studied according to series of methods and techniques,i.e.,located observation in certain study area,radio-tracing target animals methods,scanning samples in fixed transects,regular investigation on discarded cone cores in fixed transects.Results indicated that hoarding period of Eurasian red squirrels started in September and ended in November,lasting for 8-10 weeks.The beginning of hoarding was influenced by ripeness and pick(by other animals especially people)of pinecones.Eurasian red squirrels preferred to hoard bigger pinecones for high energy return.The process of hoarding can be sectioned into searching pinecones,processing pinecones,transporting a pinecone and hoarding seeds.Eurasian red squirrels peeled offscales ofpinecones whereafter held a pinecone in mouth and transported it towards a nest tree.Every pinecone was averagely taken to the base of 3 nest trees around which seeds were hoarded in batches.During each batch of hoarding the Eurasian red squirrel took about 8 seeds to construct 3-4 caches and finally 2-3 seeds were hoarded in each cache. Each Eurasian red squirrel averagely hoarded approximately 337 pinecones during the whole hoarding period in 2008.The number of hoarding pinecones by Eurasian red squirrels in Korean pine forest was almost 1 time higher than those who settled out of Korean pine forest.The hoarding habitat of Eurasian red squirrels was studied according to transects method and sample method.Result of principal component analysis pointed that several main factors affecting the selection of hoarding habitat of Eurasian red squirrels,such as distance to the Korean pine,forest type,the number of Korean pine seedlings,density and type of shrub.Selection of hoarding habitat of Eurasian red squirrels showed preference to forest where fir and spruce were in dominance.More than 50%of cone-cores were discarded within 300m along the edge and in the gap of Korean pine forest.This predicated that Eurasian red squirrels could take pinecones out of Korean pine forest. The distance of 150-600m to Korean pine forest showed no significance on the selection of hoarding habitat of Eurasian red squirrels corresponding with the radio-tracing results.The number of Korean pine seedlings in hoarding samples was notably lager than that in control samples.This indicated that hoarding habitat of Eurasian red squirrels was suitable for natural regeneration of Korean pine. Radio-tracing results manifested that Eurasian red squirrels might hoarding seeds at any moment while transporting pinecones.Within hoarded seeds by squirrels settled out of Korean pine forest, though 15%of them were hoarded out of home range,most of them were hoarded here and there within the range of 50m from nest trees.The density and canopy cover of arbors and shrubs in samples of nest trees were higher than that in areas of caches whose average diameter was about 40m.The behavioral rhythm and retrieving behavior of Eurasian red squirrels in winter was detected by radio-tracing target animals associating with investigating retrieving caches in certain area. Results revealed that the pattern of Eurasian red squirrels’ activity was unimodal in winter.The delay of outgo time and decrease of activity while was notably accompanied with the decline of temperature.The home range of Eurasian red squirrels was similarly elliptical without overlaps, 2.55±0.04hm~2.There were several nests and cache-areas within each home range per Eurasian red squirrel.Every home range could be divided into 3 parts according to the position and use rate of nests and caches,i.e.,the major area,in mid-segment of the home range;2 minor areas,situated at ambo-sides of the major area.The hoarding seeds were main source of food for Eurasian red squirrels.One Eurasian red squirrel foraged 30.7±0.4 seeds per day,accumulating totally 4500 seeds during whole winter,approximately amounting to 45 pinecones.Eurasian red squirrels principally used caches in major area.The use rate among various caches was significantly different in each phase of winter.The rate of empty retrieve evidently increased as time went deep into winter. Consequently it was supposed that the spatial memory reminded Eurasian red squirrels of retrieving cached-seeds.Eurasian red squirrels alternatively used different nests in order to avoid being preyed on by predators.The use of nests remarkably related with the use of retrieving areas.Eurasian red squirrels usually stayed over in the nearest nest after retrieving so as to reduce energy consumption. It was deduced that multi-area retrieving based on scatter hoarding in certain aeras and the relevant tactics of nests alternation were integrated response to low temperature,cache pilferages and predators in winter.On the basis of the aforesaid results,Eurasian red squirrels made a contribution to natural regeneration of Korean pine in following aspects:1.Contribution to seed bank of Korean pine(1).Retrieving residuesThe number of cached-seeds was six to twelve times as that was consumed in harvest 2008, most of which wasn’t eaten by Eurasian red squirrels in winter.(2).Hoarding bequestMany Eurasian red squirrels that died in winter bequeathed lots of hoarding sites of seeds.(3).Hoarding outside home rangeEurasian red squirrels hoarded part of seeds outside home range in winter no matter where they settled and how far from Korean pine forest.The aforementioned three sources of seeds would become part of the seed bank of natural regeneration of Korean pine if they escaped from the forage of other rodent animals.2.Determination of the dispersing range of seedsThe distribution of Eurasian red squirrels determined the dispersing range and direction of Korean pine seeds based on the directivity and region of hoarding behavior of Eurasian red squirrels.The hoarding density was highest in gap and coniferous forest 100-300m to Korean pine forest on population scale in accord with population distribution and home range structure of Eurasian red squirrels.The dispersing range of Korean pine seeds by Eurasian red squirrels included:gap and edge of Korean pine forest,inner and gap of natural coniferous forest as well as natural mixed coniferous and broad-leaved forest where Eurasian red squirrels settled.There is rarely direct relationship between regeneration of Korean pine in broad-leaved forest(especially younger broad-leaved forest)and Eurasian red squirrels’ hoarding behavior.更多还原