长期施肥对麦田大型土壤动物群落结构的影响

于2007、2008年春季在中国科学院封丘农业生态实验站,研究长期定位施肥对麦田大型土壤动物群落结构的影响。调查共获得大型土壤动物3068头,隶属8纲,19目,28科。不同施肥处理条件下土壤动物类群数差异显著(F=2.51, P＜0.05, df=55),个体数差异极显著(F=8.99, P＜0.01, df=55)。结果显示,大型土壤动物的类群数和个体数在有机肥和营养均衡条件下较高,缺磷条件下较低。土壤动物多样性指数(H')以有机肥和营养均衡条件下显著高于营养不均衡和不施肥处理(P＜0.05)。主成分分析结果显示,第一主成分贡献值47.14%,第二主成分贡献值30.10%。经线性检验第一主成分与土壤动物个体数(y=0.335x-2.163,R²=0.51)和类群数(y=0.042x-1.25,R²=0.67)均呈线性关系。总之,长期施用有机肥和营养均衡大型土壤动物群落构成相似。土壤有机质和磷含量是影响土壤动物群落构主要生态因子。     

四川扭角羚春冬季对栖息地的利用初步研究

1998年3月至1999年2月,在四川省青川县唐家河自然保护区,对四川扭角羚（Budorcas taxicolor tibetana)春冬季对栖息地的利用进行了初步研究。结果表明,影响四川扭角羚春季栖息地利用的主要生态因子为人为干扰,植被型、乔木大小、乔木距离,乔木密度、食物丰富度,海拔,坡位、郁闭度,影响冬季栖息地利用的主要生态因子为人为干扰。植被型,乔木距离,灌木大小,灌木密度,动物干扰度,乔木大小、灌木距离,坡位,郁闭度,水源,四川扭角羚春冬季栖息地利用的分离主要表现为食物丰富度,乔木大小,乔木密度,乔木距离,植被型,水源,坡位等生存因子的分离。     

黄河三角洲自然保护区东方白鹳的巢址利用

2009年3-5月,在黄河三角洲保护区,运用Vanderploeg和Scavia选择指数和资源选择函数对25个东方白鹳巢址的利用进行了研究。结果表明:东方白鹳偏好选择在芦苇沼泽中的电线杆上筑巢,巢区水面比例较大,样方内水深度>15cm,植被较高,盖度较大,植被密度200-500根/m²,巢址距明水面、芦苇沼泽、树林距离较近,明水面深度<0.5m,距离人为干扰、农田、草地较远。东方白鹳巢址利用的资源选择函数为:logist(p)=-0.206-2.773×距明水面距离+2.200×距公路距离+1.444×距轻度干扰地距离+1.205×距草地距离＋1.191×植被密度,模型正确率:88.6％,R²=0.721。食物、人为干扰和植被密度是影响东方白鹳巢址利用的主要因素。     

人为干扰对风水林群落树种组成及多样性的影响

研究了人为干扰对东莞市大岭山镇风水林群落树种组成及多样性的影响。多响应置换过程（MRPP）分析结果表明,风水林树种组成在轻度干扰与中度干扰（P=0.023,A=0.216）、重度干扰间（P=0.045,A=0.226）存在显著差异,而中度干扰和重度干扰间则不存在显著差异（P=0.124,A=0.148）。随着人为干扰强度的增大,轻度干扰、中度干扰和重度干扰下林木胸径和树高随之减小。Shannon-Wiener指数、Simpson指数、Margalef指数和Pielou指数一致呈现出中度干扰＞重度干扰＞轻度干扰的格局,与中度干扰假说相符合。轻度干扰、中度干扰和重度干扰下Whittaker β多样性分别为0.501、0.647和0.889,较好地反映了3个风水林在不同人为干扰强度下的生境异质性.     

农林复合生态系统防护林斑块边缘效应对节肢动物的影响

于2008和2009年在黄淮海平原典型地区商丘民权林场(34°31'-34°52'N, 115°00'-115°28'E)进行。选择杨树林、槐树林和杨槐混交林3种人工林模式,调查节肢动物群落构成、生物多样性及边缘效应对节肢动物群落结构的影响。结果显示,节肢动物科级水平上不同年份间的类群数和个体数差异都不显著(P>0.05),防护林不同模式间个体数(df=2, F=59.48, P<0.001)和类群数(df=2, F=15.44, P<0.001)差异均显著。3种防护林中以杨树林物种丰富度指数较高,S_杨树林(9.65)>S_{杨槐混交林}(8.78)>S_槐树林(7.47);生物多样性指数H'_杨树林(1.78)>H'_{杨槐混交林}(1.65)>H'_槐树林(1.46),其中杨树与槐树林的S和H'差异显著(P<0.05)。杨树林和槐树林边缘效应对节肢动物群落的影响大于杨槐混交林,林地边缘节肢动物的类群数和个体数均较高。节肢动物类群组成表现为林地边缘的偶见种和农田种多于林内。杨树林和槐树林边缘节肢动物多样性指数较高,向林内40m显著下降;而杨槐混交林边缘效应对节肢动物多样性指数的影响较小。综合分析认为,杨树林和槐树林边缘效应对节肢动物群落结构和多样性的影响距离为40m,杨槐混交林距离为20m。单一树种农田防护林斑块不小于80m宽,混交林斑块不小于40m宽,可以保护林内物种生存,维持农田生态系统生物多样性。     

体重和盐度对中国蛤蜊耗氧率和排氨率的影响

采用室内实验生态方法研究了不同软体部干重((1.022 ±0.821)、(0.557±0.266)、(0.303±0.277) g)和盐度(13、18、23、28、33)对中国蛤蜊(Mactra chinensis Philippi)耗氧率和排氨率的影响。结果表明:盐度、个体大小对中国蛤蜊耗氧率的影响极显著(P＜0.01),二者的交互作用对中国蛤蜊耗氧率影响显著(P＜0.05);中国蛤蜊单位体重耗氧率(R₀)与软体部干重(W)负相关,符合幂函数方程R₀=aW^-b, 其中a值的取值范围是0.695-1.762,平均值为1.449,b值的取值范围是0.446-0.587,平均值为0.542。盐度、个体大小对中国蛤蜊排氨率影响也极显著(P＜0.01);随着中国蛤蜊个体的增大,其单位体重排氨率逐渐降低;排氨率与其软体部干重呈负相关,它们之间可以用幂函数R_N=a₀W^-b₀表示。单位体重耗氧率和排氨率与盐度(S)、软体部干重(W)的二元线性回归方程分别为: R_O=2.111-1.817W+0.49S (R²=0.546, F=34.294, P＜0.001);R_N=168.186-120.589W+1.734S (R²=0.561, F=36.418, P＜0.001)。     

我国东北土壤有机碳、无机碳含量与土壤理化性质的相关性

根据黑龙江、吉林、辽宁省和内蒙古地区相关历史资料数据,分析了我国东北表层土壤(0-50 cm)土壤相关理化性质与有机碳、无机碳的相关性,得到如下结论:土壤全氮、碱解氮、全磷、速效磷、速效钾、K⁺离子交换量、Fe₂O₃、P₂O₅、总孔隙度均与土壤有机碳含量呈显著正相关(R²=0.10-0.94, n=38-345, P<0.0001),但与土壤无机碳含量则大多呈显著负相关(R²=0.11-0.30, n=37-122, P<0.01);与此相反,土壤pH值、容重与土壤有机碳呈负相关(R²=0.36-0.42,n=41-304, P<0.0001),而与无机碳呈显著正相关(R²=0.29-0.31,n=39-125, P <0.01)。表层土壤有机碳、无机碳与土壤理化性质呈相反变化趋势的结果说明,由于土壤利用方式变化所导致的土壤理化性质改变对土壤无机碳和有机碳可能具有相反影响。在研究土壤碳平衡过程中,应该充分考虑这种关系所导致的相互补偿作用,即有机碳的增加,可能意味着无机碳的减少,或者反之。目前研究中普遍忽略无机碳的变化,可能导致生态系统碳收支计算显著偏差,所获得的经验拟合方程有利于对我国东北地区土壤碳平衡研究产生的这种偏差进行粗略估计。     

京杭运河邵伯高邮段栖息地破碎化对狗獾种群数量分布的影响

栖息地破碎是生物多样性下降的主要原因之一。栖息地破碎引起的面积效应、隔离效应和边缘效应能影响动物种群的绝灭阈值、分布、多度、种间关系以及生态系统过程, 最终影响动物种群的数量分布。2006年10-11月和2007年10-11月, 利用全球定位系统(GPS)、地理信息系统(GIS)和样方法定量分析京杭运河邵伯至高邮段狗獾栖息地破碎化程度, 确定不同斑块的面积、斑块距离、斑块隔离度以及栖息地质量对斑块中狗獾数量分布的影响。结果表明, 各个斑块内狗獾的洞口数、粪堆数与该斑块的面积显著的正相关(r=0.961, P=0.039; r=0.999, P=0.023), 但与斑块距离、斑块隔离度无显著的相关性(P>0.05)。栖息地的质量也会影响狗獾的数量分布, 多元线性逐步回归分析表明, 人类干扰和与栖息地的郁闭性显著的影响狗獾的数量分布。以上结果说明, 京杭运河邵伯高邮段栖息地的破碎化程度对狗獾的数量分布还没有造成显著的直接影响, 但会间接降低栖息地的质量, 进而影响狗獾的生存。     

兴安落叶松林生物量、地表枯落物量及土壤有机碳储量随林分生长的变化差异

有关生物量碳随林分生长变化研究较多,而相关土壤有机碳储量随林分生长变化研究较少且结论争议较大。通过对二者随林分生长变化差异的比较,旨在探讨是否可以通过简单林分生长指标来判断土壤有机碳的变化规律。对兴安落叶松人工林分布区内139个样地的生物量与土壤碳动态研究结果表明:(1)林龄是指示生物量碳累积的可靠参数。兴安落叶松个体大小(胸径、树高和单株生物量)随着林龄的增大不断增加,相关性显著(P<0.001),而林分生物量密度随林龄的增大呈线性上升(R²=0.2-0.6,P<0.001)。(2)地表凋落物量与林龄表现显著的二次曲线相关,前37a上升而后开始下降。地表凋落物量与林木大小、生物量密度均相关显著(R²=0.14-0.82,P<0.001),但与树高相关性最高,显示树高变化对于评价地表枯落物生物量可能更有效。(3)林龄、林木大小和林分生物量密度均与土壤不同层碳存在相类似的相关关系。深层土壤有机碳(>40cm)与林龄显著负相关(P<0.05),表层土壤有机碳有增加趋势 (P>0.05),这使得0-40 cm与40-80 cm土壤有机碳储量比值随林龄增加而显著增加(P<0.01);与此类似,林木平均大小也与深层土壤有机碳显著负相关(P<0.05),而表层与深层有机碳储量比值随林木大小(胸径与树高)的增大也呈显著上升趋势(P<0.05);但同时考虑林木个体大小和林分密度的林分生物量密度(地上和地下),并没有发现明显的显著相关关系。这些结果说明,评价土壤有机碳变化的指标中,林龄、树高和胸径可能更优于较为复杂的生物量密度等指标。考虑到深层土壤较表层具有更长期的稳定性,这种表层与深层土壤有机碳比值的增加,意味着土壤碳有向表层积聚而深层减少的趋势,这可能使得土壤有机碳更容易受外界环境变化(如火灾等)的影响。落叶松人工林群落碳储量随林龄增加的变化规律明显,除了占主要部分的生物量碳之外,土壤碳累积值得关注,这一发现对于以固碳增汇为目标的碳汇林建设具有指导意义。     

广西马山岩溶植被年龄序列的群落特征

石漠化地区是我国西南植被恢复和生态重建的重点和难点地区。通过对马山县岩溶植被年龄序列(石漠、草丛、灌丛、小乔林和成熟林)5个演替阶段15个样地(20 m×50 m)的系统取样调查,研究了停止人为干扰后岩溶植被的更新、演替及群落特征的变化。结果表明:沿石漠、草丛、灌丛、小乔林、成熟林的顺向演替发展,群落各层次的覆盖度存在显著差异(P<0.05),乔木层覆盖度以成熟林最大,灌木层覆盖度以小乔林最高,而草本层覆盖度以灌丛最高;重要值≥10.00的科、属、种最大值出现在小乔林;不同演替阶段群落不同层次的结构明显不同,乔木层的植物密度存在显著差异(P<0.05),以小乔林最高;成熟林灌木层的植物密度显著低于小乔林和草丛(P<0.05),与石漠和灌丛差异不显著(P>0.05);森林阶段草本层的植物密度显著低于灌丛、草丛和石漠(P<0.05);群落的物种丰富度随着顺向演替发展而增加,但不同演替阶段不同层次的丰富度变化不同,草本层的物种丰富度以草丛阶段最大,成熟林最小;灌木层的丰富度以小乔林阶段最大,石漠阶段最小;乔木层的丰富度以小乔林最大,成熟林有所下降;不同演替阶段群落草本层的生态优势度无显著差异(P>0.05),而灌木层和乔木层均存在显著差异(P<0.05)。岩溶植被恢复可分为恶劣物理环境阈值和顶极种缺乏的阈值两个阶段,每一个阶段内由不同功能特征的驱动种和关键种决定着群落的演替方向和速度,越接近演替后期,顶极种越丰富,群落驱动种和关键种向高级、大型和长寿植物发展的趋势越明显。     

Distribution and population density of badgers Meles meles in Luxembourg

1. The distribution and density of Eurasian badgers Meles meles in Luxembourg was estimated by gathering information about the location of badger setts with a questionnaire survey, by visiting 708 setts in order to classify them as ‘main setts’ or ‘outliers’, and by estimating social group size by directly counting emerging badgers. 2. Badgers were found to be widely distributed in Luxembourg, with a minimum main sett density of 0.17 setts/km². Setts were sited preferentially in forest habitat. The mean minimum group size was 4.6 badgers. 3. The Luxembourg badger population was conservatively estimated to contain at least 2010 adult and young badgers (95% CI 1674–2347) in spring 2002, equivalent to a density of 0.78 adult and young badgers/km² (95% CI 0.65–0.91). This is moderate compared to most of continental Europe.     

The distribution of Eurasian badger, Meles meles, setts in a high-density area: field observations contradict the sett dispersion hypothesis

Are setts significant determinants of badger socio‐spatial organisation, and do suitable sett sites represent a limited resource, potentially affecting badger distributions? The factors determining diurnal resting den, or sett, location and selection by Eurasian badgers Meles meles L. were investigated in Wytham Woods, Oxfordshire. 279 sett sites were located. The habitat parameters that were associated with the siting of these setts were analysed and associations were sought between sett location and character and the body condition and body weight of resident badgers Habitat characteristics in the vicinity of setts were significantly different from randomly selected points. Badgers preferentially selected sites with sandy, well‐drained soils, situated on NW‐facing, convex and moderately inclined slopes at moderate altitude. There was no evidence that sett morphology (number of entrances, sett area, number of hinterland latrines) was affected by the surrounding sett site habitat characteristics. Mean body weight was significantly higher for badgers occupying territories with setts in sandy soils, situated on NW‐facing slopes, than in territories with less optimal sett characteristics. Contrary to the hypothesis that the availability of sett sites was limiting, and therefore that sett dispersion dictates the spatial and social organisation of their populations, the badgers were clearly able to excavate new setts. On our measures, these new setts were not inferior to old established ones, despite occupying subsequently exploited sites; the badgers utilising these new setts had neither lighter body weights nor poorer body condition scores. During the period of our study badgers have manifestly been able to dig numerous new setts; as satisfactory sites still remain available, this indicates that suitable sett sites have not yet become a limiting resource. There was no relationship between sett age and the characteristics of the site in which it was dug, as suitable sites were not limiting. Significantly, population expansion during the decade 1987–1997 was not constrained by lack of setts, rather the main proliferation in setts occurred after the population size had peaked in 1996. Some implications for the management and conservation of the Eurasian badger are considered.     

The density and distribution of badger setts in the Sudety Mountains,Poland

The density and distribution of badgerMeles meles (Linnaeus, 1758) setts was estimated by questionnaires and field studies, carried out in the Sudety Mountains between 1995–2002. The questionnaire referred to the whole territory of Polish Sudety Mts, while field studies were conducted in four different habitat types: low mountains with a mosaic farm-forest landscape, highly industrialised hilly areas, high mountain ranges of natural character and high mountain ranges of severe microclimate and heavily destroyed tree stands. On the basis of both questionnaires and field surveys, a total of 378 badger setts, classified according to their size and status, were identified. Among these, 119 (31.5%) were situated on three areas, while in the fourth area we did not find any badger setts. According to their size and traces of intensive occupation, 54 setts were regarded as main badger setts. The mean density of main setts on three areas was much the same and amounted to 0.05–0.07/km² of their total surface, despite differences in their natural environment and agricultural or industrial changes in landscapes. In the Sudety Mts badgers selected settlements in forest habitats, bordering rich in food open areas. The density of main setts in forest areas ranged from 0.12 to 0.33/km² depending on the proportion of forest, type and age of tree stands and size of forest complexes. The mean distance of main setts from open areas ranged from 209 to 280 m. The mean nearest neighbour distance (NND) between main setts ranged from 2.85 to 3.75 km. The home range size estimated for a social group varied from 7.9 to 13.6 km². The highest occupied setts of our study were found on the ?nie?nik Massif, at an altitude of 700 m a.s.l.     

张广才岭藏獾洞穴生境选择

2008年9月至2009年8月,在黑龙江省方正林业局新风林场,用不定宽样线法对藏獾洞穴生境选择进行研究,共记录了55组藏獾洞穴,藏獾洞口平均直径为(27.40±7.15)cm,洞深平均为(84.18±22.04)cm,倾角平均为(26.36±9.10)°,洞口总数=3.02个常用洞数+0.80个不常用洞数+0.56个废弃洞数。相对于对照样方而言,藏獾洞穴更偏爱选择位于郁闭度和植被盖度小,灌木密度大、距离近,乔木距离远,距水源和农田近、人为干扰距离远,坡度较缓的向阳中坡位的生境。资源选择函数模型为:logit(p)=246.980-1.059×植被盖度-0.703×距水源距离-1.403×坡度-45.005×坡向,模型的正确预测率为93.9%。     

Eurasian badger habitat selection in Mediterranean environments: Does scale really matter?

It is widely believed that spatial scale affects habitat selection, and should influence management options, especially for species with wide geographic distribution or large territories. Eurasian badger habitat selection has been well studied throughout most of its European distribution range, but never at multiple spatial scales. We used compositional analysis to assess habitat selection of Eurasian badgers in southern Portugal at four spatial scales (1, 4, 25, and 100 km²). We assessed habitat use from setts, latrines and footprints presence, and road kills. Oak woodlands with understorey were selected at all scales, being the most preferred habitat at 3 scales (1, 4, and 100 km²). Pastures were most selected at the scale of the 25 km² cell, but their use was not significantly different from oak woodland with understorey. Shrubs and pastures were also secondly important at the majority of scales. Contrary to findings at northern latitudes, deciduous forests decreased in importance as cell size increased. In the highly humanized and fragmented landscape of southern Portugal, Eurasian badgers are selecting the matrix of oak woodlands interspersed with patches of pastures, shrubs and riparian vegetation. In these oak woodlands, scale does not have a marked effect. Management for badgers should provide, for at least, 30% of oak woodland cover at all scales. Our study illustrates the across-scale importance of maintaining the historically human altered, sustainable and unique landscape and land use system – the montado.     

Changes in the prevalence of badger persecution in Northern Ireland

Animal populations generally increase after release from hunting pressure and/or cessation of illegal persecution. Implementation of full legislative protection of the Eurasian badger Meles meles in Great Britain is thought to have led to increases in badger abundance due to reduced levels of persecution. Conversely, prevalence of badger persecution in Northern Ireland was historically much higher than in Great Britain, and badger abundance remained stable over time despite similar legislative protection. We examined temporal changes in the prevalence of badger sett disturbance in Northern Ireland from 1990/1993 to 2007/2008 in relation to population status. A total of 56 (12.6%) of 445 setts surveyed during 1990/1993 had been disturbed compared to 29 (4.4%) of 653 setts during 2007/2008. This was a significant decline (−65%) in the incidence of sett disturbance over the 14–18-year period. Most notably, the incidence of digging at badger setts, indicative of local badger baiting activity, declined from 50% to 3.5% of disturbed setts. Signs of recent disturbance were significantly more frequent at disused setts suggesting that once disturbed, badgers may vacate a sett. The number of badger social groups in Northern Ireland did not differ between the two study periods, suggesting that previously high levels of badger persecution did not limit the number of badger social groups. The stability of the badger population in Northern Ireland compared to the growing population in Great Britain cannot be attributed to changes in the prevalence of persecution. Differences in the trajectories of both populations could be due to a range of factors including climate, habitat composition and structure, farming practices or food availability. More work is needed to determine how such factors influence badger population dynamics.     

Spatial Targeting for Bovine Tuberculosis Control: Can the Locations of Infected Cattle Be Used to Find Infected Badgers?

Bovine tuberculosis is a disease of historical importance to human health in the UK that remains a major animal health and economic issue. Control of the disease in cattle is complicated by the presence of a reservoir species, the Eurasian badger. In spite of uncertainty in the degree to which cattle disease results from transmission from badgers, and opposition from environmental groups, culling of badgers has been licenced in two large areas in England. Methods to limit culls to smaller areas that target badgers infected with TB whilst minimising the number of uninfected badgers culled is therefore of considerable interest. Here, we use historical data from a large-scale field trial of badger culling to assess two alternative hypothetical methods of targeting TB-infected badgers based on the distribution of cattle TB incidents: (i) a simple circular ‘ring cull’; and (ii) geographic profiling, a novel technique for spatial targeting of infectious disease control that predicts the locations of sources of infection based on the distribution of linked cases. Our results showed that both methods required coverage of very large areas to ensure a substantial proportion of infected badgers were removed, and would result in many uninfected badgers being culled. Geographic profiling, which accounts for clustering of infections in badger and cattle populations, produced a small but non-significant increase in the proportion of setts with TB-infected compared to uninfected badgers included in a cull. It also provided no overall improvement at targeting setts with infected badgers compared to the ring cull. Cattle TB incidents in this study were therefore insufficiently clustered around TB-infected badger setts to design an efficient spatially targeted cull; and this analysis provided no evidence to support a move towards spatially targeted badger culling policies for bovine TB control.     

Phylogenetic relationships and genetic diversity of badgers from the Korean Peninsula: Implications for the taxonomic status of the Korean badger

Accurate taxonomic classification of wildlife species is crucial for guiding biological research and for developing effective management and conservation programs. The taxonomic status of Eurasian badgers from South Korea remains poorly resolved. Here we assessed the phylogenetic relationships and genetic variation of Eurasia badgers using partial mitochondrial fragments to elucidate the evolutionary history and taxonomic status of badgers from the Korean Peninsula. Forty-eight unique haplotypes from 125 individuals were observed. Phylogenetic reconstructions and reduced median networks indicate that Eurasian badgers consisted of four geographic clades (Japan, Eastern Eurasia, Western Eurasia, and Caucasus) with a relatively weak split observed within Eastern Eurasia. Estimated divergence time between the Japanese and Eastern Eurasian clades, including the Korean population, was 467,100 years (69,200–1,085,500 years). The results of this study support the hypothesis that the Japanese badger migrated from the Eurasian continent over the Korea-Japan land bridge and that the Korean Peninsula was an important refugia during the Pleistocene. Our study confirmed that the South Korean badger, Meles meles, belongs to the Eastern Eurasian clade. Based on these results and those of previous studies, we recommend that the scientific name of the Korean badger be changed from M. meles to Meles leucurus (Asian badger).     

Resource dispersion and badger population density in Mediterranean woodlands: is food,water or geology the limiting factor?

Eurasian badgers, Meles meles, in Mediterranean cork‐oak woodlands live in small groups within territories that embrace a mosaic of habitats where several setts (dens) are scattered. Assuming that their population density was related to home range sizes and that this in turn was influenced by food and water availability and the existence of substrate suitable for sett construction, we explored the relationship between these parameters. Two biotopes were predominantly important in providing food security to badgers in the ‘Grândola’ mountain study area: olive groves and orchards or vegetable gardens. Analysis of the mean total area of these two habitats in the ranges of radio‐tracked badgers permitted us to extrapolate to an estimate that the 66 km² encompassed eleven areas with the capacity to support badger groups each composed by 6–8 individuals. Since only three groups populated the area we concluded that food availability was not limiting badger density. Sites with surface water in summer (the dry season) seem sufficient to support more badger groups than existed, leading us to believe that this factor was also not limiting badger density. Simultaneously, using a logistic regression model and the biophysical characteristics of sett sites as explanatory variables, four predictor variables determined sett location: the existence of a geological fault/discontinuity, ridges, valleys and the distance to abandoned farm houses, of which the former had the higher odds ratio, being thus the best sett location predictor. Indeed, 56% of the areas predicted with >80% confidence to contain a badger sett were encompassed within a known home range. Therefore, our results suggest that, in Mediterranean cork oak woodlands in SW Portugal, the main factor limiting badger's density is the availability of suitable sites for setts. However, in areas where suitable sites for burrows existed, but food patches were absent, badgers were not found. This could indicate that the presence of both factors was necessary for badgers, although in this area sites suitable for digging setts appeared to be the primary limiting factor.     

不同林龄胡杨克隆繁殖根系分布特征及其构型

以中龄林和成熟林胡杨为研究对象,采用挖剖面和根窗的方法,研究胡杨繁殖根系分布、根系构型,以及胡杨根蘖与繁殖根系构型之间的关系。结果表明:(1)细根(d<2 mm)的根长密度、根表面积密度,随深度增加呈现指数函数分布;(2)中龄林细根的根长密度、根表面积密度在0—90 cm各层都是显著大于成熟林的对应指标(P<0.05),成熟林的中等粗根(5 mm0.05),且两种林龄的一级侧根数、分枝角度亦无显著差异(P>0.05);(5)对比两种林龄不同根序上的根蘖芽发现,二级根上不定芽个数均是同组一级根上不定芽个数的3—4倍;基于以上对胡杨根系的功能权衡的分析,得出:细根对胡杨根系构型有重要的影响,在胡杨根系功能权衡中扮演重要角色。