道路对陆栖野生动物的生态学影响

道路网络为大多数景观所共同具有的空间特征,在增进社会财富、方便人们生活的同时。也会产生严重的生态学后果。就道路对陆栖野生动物的生态学影响进行了综述。道路交通导致动物死亡。已成为野生脊椎动物死亡的首要原因;阻碍动物个体在同种种群问的交流以及在互补性资源间的周期性迁移;迫使森林内部种、边缘敏感种主动回避道路栖息地;导致道路区域栖息鸟类繁殖下降;有利于小型物种沿道路边缘扩散,造成生物入侵。道路区域为一种特殊的边缘。对一些边缘物种以及其它被吸引过来的动物来说是一种死亡陷阱。这些影响的综合作用会导致孤立的小种群问题。从而严重威胁到渐危濒危物种的长期存活。     

片段化景观中壳斗科植物种子捕食和扩散模式

生境片段化伴随的面积效应和边缘效应, 可改变分散贮食动物的竞争强度、觅食行为以及隐蔽条件, 影响种子捕食和扩散模式。阐明生境片段化对多物种种子捕食和扩散的影响, 对理解片段化生境中的植物更新和生物多样性维持十分重要。该研究在浙江省千岛湖地区的岛屿和大陆上开展了针对6种壳斗科植物的种子捕食和扩散实验, 分析了物种、分散贮食动物相对多度、种子产量、岛屿大小和边缘效应如何共同影响种子命运和种子扩散距离。主要结果: (1)种子命运和扩散距离在物种间存在显著差异; (2)大陆比岛屿有更长的种子留存时间, 小岛种子留存时间最短, 岛屿内部比岛屿边缘有更长的种子留存时间; (3)物种和岛屿大小对种子原地取食率存在交互作用, 白栎(Quercus fabri)种子在大岛上有更高的原地取食率; (4)种子在小岛上有最高的扩散率, 分散贮食动物相对多度对种子扩散后贮藏率有负效应。表明在千岛湖地区, 生境片段化改变了种子捕食和扩散模式, 且面积效应对不同物种的种子捕食和扩散模式产生了不同作用, 从而影响森林群落更新和生物多样性维持。     

道路网络对物种迁移及景观连通性的影响

道路对区域景观产生破碎化及阻碍效应,使得生态过程发生受阻、景观功能受损。科学评估道路的生态效应对指导道路选线、生态恢复工程及景观规划有重要价值。本文采用阻力面概念和最小耗费模型,实现了景观阻力、斑块质量、廊道畅通性和景观连通性的计算,定量分析了物种迁移过程中道路网的干扰程度。结果表明:道路引起生态廊道长度平均增加30%,廊道曲率平均增加0.19;道路也使廊道通畅性平均降低90%,影响程度与廊道耗费值呈线性相关,系数为0.76;整体景观连通性下降30.8%,扩散能力越弱的廊道所受道路阻碍效应越强。本文建立的模拟评价方法可用于确定景观尺度上特定生态过程的关键格局,同时也可为景观生态规划中生态廊道设计及景观连通性定量分析提供科学依据。     

三峡库区消落带4种适生植物根际与非根际土壤养分与酶活性特征研究

三峡库区消落带植被修复过程中,物种的更替对库区土壤的地球化学循环产生潜在影响。以三峡库区忠县石宝寨汝溪河消落带植被修复示范基地165-170 m海拔段人工种植狗牙根、牛鞭草、落羽杉以及立柳根际与非根际土为试验对象,探究其根际与非根际土壤的养分含量及酶活性差异,以阐明不同物种的生长适应性及其根际养分利用策略,比较不同物种对库区土壤的营养改良作用。结果表明：（1）三峡库区消落带4种适生植物根系活动导致根际与非根际土壤养分因子以及土壤酶活性产生差异,不同物种的栽植均在一定程度上使库区土壤营养条件得以改善;（2）碳、氮两种元素在4种适生植物根际土壤中发生不同程度的富集,但磷素与钾素在不同物种根际与非根际土壤之间的变化不一致;（3）蔗糖酶、脲酶以及酸性磷酸酶在4种适生植物根际土中均表现出一定程度的根际正效应（R/S>1）,且狗牙根对3种土壤酶的根际活化效果最为明显,其根际效应分别高达2.39、1.89和2.7;（4）在植物根系的调控下,根际土中有机质与氮素、磷素以及钾素的相关性更为显著,而非根际土壤中,仅钾素与有效氮、有效磷呈显著负相关,其余各土壤养分因子之间均无显著相关性;（5）与落羽杉和立柳两木本植物相比,狗牙根与牛鞭草两草本植物根际具有更为合理的养分调节模式,对库区土壤的改良效果更好。     

生态群落物种共存的进化机制

本文概述了目前对生态群落的物种共存研究中存在的若干问题及动、植物群落物种共存机制的研究进展。植物群落的物种共存主要介绍与环境、种子再迁移、生态位分化、竞争平衡理论、种库假设、再生生态位等有关的几种假设、生态学上相似种的共存及“原”群落概念等。动物群落的物种共存机制主要从以下几方面叙述：（1）异质环境中的资源分割,主要指动物斑状滋养的不同利用;（2）避免竞争排斥的行为机制,如边缘效应、聚群效应、扩散行为、相互作用和干扰;（3）特化者和泛化者的共存,包括：竞争是物种向多功能进化的作用力、最佳觅食理论与生态学特化及特化概念的发展。最后指出进一步研究的方向。     

人类活动效应对物种多样性影响的动力模拟——以洪湖湿地生境毁坏对水鸟物种多样性的影响为例

提出了随时间变化的人类活动效应对物种多样性影响的多物种竞争非自治动力模式,并以洪湖为例模拟了湿地水鸟物种多样性对人类活动效应（生境持续毁坏）的响应过程。模拟发现：对于强．强物种,生境的持续破坏使得湿地水鸟的物种多度大幅度减小,并发生优势种群的更替;对于弱-弱物种,将导致大批的弱物种种群迅速灭绝,而余下的弱物种种群将做准周期振荡;尽管停止对湿地生境的持续毁坏,仍会使一批弱物种种群继续走向灭绝,并且使得原来最强的几个种群最终灭绝。物种灭绝对生境毁坏的这种时间滞后性,即破碎的生境中存在着一些“活死者”,必须引起自然保护学家的关注,否则会低估了实际处于灭绝边缘的物种的数目,从而影响正确的物种保护决策的制订。     

北京温榆河-北运河生态廊道自生植物多样性对城市化的响应

城市化进程带来的城市生境破碎化对城市野生动植物多样性产生了巨大的影响,而生态廊道作为城市中的绿色线性空间,对缓解城市化进程下的生物多样性丧失具有重要作用。自生植物不仅是城市植物多样性的重要组成部分,也为乡土动物提供了赖以生存的资源,在低维护植物景观营造中起到关键作用。聚焦北京温榆河-北运河生态廊道,在对廊道自生植物总体物种组成进行分析的基础上,探究城市化梯度上自生植物物种组成与多样性特征差异,并分析不同自生植物种群对城市化水平的适应性。共调查到温榆河-北运河自生植物195种,隶属于73科,156属,以自生草本植物为主。各城市化水平下自生木本植物的α多样性无显著差异;中低城市化水平下草本植物的α多样性显著高于其他水平（P<0.05）。随着城市化水平升高,自生乔木和一、二年生的β多样性升高,自生多年生草本、自生入侵植物和外来植物的β多样性值下降。在城市化梯度上的生态位宽度均值排序为入侵植物 > 乡土植物 > 国外外来植物 > 国内外来植物。将生态廊道自生植物按照生态位宽度划分为广适型、中适型和狭适型,并依据生态位重叠筛选了与15种入侵植物在城市化梯度上适应性相近的自生乡土植物种类。本研究结果可以为营造稳定的低维护自生植物群落,抵抗外来入侵植物的扩散,实现城市河流生态廊道的生物多样性保护功能提供参考。     

道路生态学研究进展

“道路生态学”是当代景观生态学的最新研究领域。重点探讨道路生态学和生态道路网的研究进展。从景观生态学的点效应、廊道效应和边际效应出发 ,引入景观生态网络的概念 ,即由点、线、网按照一定等级结构、功能分工和空间秩序组合成的生态网络体系 ,其中道路网和水网是最主要的表现形态。根据网络理论构造网络结构影响度模型 ,在 GIS和 RS的支持下 ,通过对北京局部地区道路网动态模拟的分析表明 ,道路网对其他景观的影响是通过点效应、廊道效应、点 -廊道 -网络叠加效应共同作用的结果 ,这种影响与道路网络密度和道路影响带的范围成正比。因此 ,为了最大限度减少道路网对自然生态系统的干扰与破环 ,提出生态道路网络建设的 8点建议     

鄂尔多斯高原风蚀沙化梁地克隆植物的分布及其与物种多样性的关系

 采用样线法和点样法对鄂尔多斯风蚀沙化梁地上的植物进行了调查,研究了梁地上克隆植物的分布、克隆植物在群落中的重要性及其与群落物种多样性之间的关系。结果表明：1）在梁顶的典型草原植物群落和梁底的滩地盐生植物群落中克隆植物的物种丰富度较高,而在梁坡的沙生植物群落中较少,非克隆植物物种在梁顶出现频率较高,在梁坡和梁底较少;密集型克隆植物物种丰富度的变化与非克隆植物相同,游击型克隆植物在梁顶植物群落中没有出现,在梁坡群落中也很少,而在梁底的滩地中较多。2）梁底群落中克隆植物的重要值高于梁顶和梁坡群落中克隆植物的重要值,梁顶与梁坡群落中非克隆植物的重要值高于梁底群落中非克隆植物的重要值;在梁坡与梁底群落中,克隆植物的重要值都高于非克隆植物的重要值,而在梁顶群落中克隆植物与非克隆植物的重要值之间无差异;梁顶与梁坡群落中密集型克隆植物的重要值高于梁底群落中密集型克隆植物的重要值,而游击型克隆植物的重要值在梁底群落中较高;在梁顶与梁坡群落中,密集型克隆植物的重要值分别高于游击型克隆植物的重要值,而在梁底群落中,密集型克隆植物的重要值低于游击型克隆植物的重要值。3）梁顶的典型草原植物群落中,群落物种多样性随非克隆植物的重要值、克隆植物的重要值、密集型克隆植物的重要值的变化趋势相同,都为抛物线型。梁坡的沙生植物群落中,群落物种多样性与非克隆植物的重要值呈正相关,而分别与克隆植物和密集型克隆植物的重要值呈负相关。梁底的滩地盐生植物群落中,群落物种多样性与非克隆植物的重要值呈正相关,而与克隆植物和游击型克隆植物的重要值呈负相关。     

秦岭大熊猫种群扩散格局及研究方法

种群扩散格局是研究种群扩散规律和机制的关键信息,也是制定物种保护对策的重要基础。大型动物种群扩散格局研究方法为扩散生态学研究的薄弱领域,并制约扩散生态学的发展。以秦岭大熊猫为研究对象,根据2000年以来的种群调查数据,基于大熊猫领域的特性,利用GIS的扩展区分析功能和景观分析方法研究了大熊猫种群分布区及动态;基于聚集的特性,利用GIS的核密度分析功能对大熊猫种群多度和聚集状况及空间变化进行了分析。发现2012年的秦岭大熊猫种群分布区较2000年增加5.5%(即15307.8hm~2),高密度种群聚集区从2处变成1处,种群聚集程度进一步增加、聚集格局的完整性大大提升,尤以中密度聚集区增长最显著,种群格局呈明显的分布区扩张、聚集度增加的态势。表明基于物种的生物学特性,立足于种群分布和多度格局变化,通过长期调查和监测可以有效掌握物种的种群扩散格局;大型动物可根据其生物学特性探索可行的方法与量化种群扩散的参数来研究其扩散格局,从而促进大型动物种群扩散研究的开展。     

Plant distribution and dispersal mechanisms at the Hassayampa River Preserve, Arizona, USA

This study focuses on the relationships between plant dispersal syndromes and plant distributions at the community scale. Species composition and cover are reported from 29 10 × 20-m vegetation plots along five topographic cross-sections in the riparian zone of the Hassayampa River Preserve, Arizona. We find that spatial patterns of dispersal guilds vary within the flood plain of this semiarid region river. Our main results are: (1) wind-dispersed species are fairly evenly distributed at all elevations and distances from the river, whereas cover of animal-dispersed species increases with elevation above, and at greater distances from, the river; (2) wind-dispersed species are proportionally more abundant in the pioneer Populus–Salix community, whereas plants in the late-seral Prosopis community are predominantly animal-dispersed; (3) most of the species classified as obligate-wetland and facultative-wetland are wind-dispersed, whereas facultative-upland and obligate-upland species are mostly animal-dispersed; and (4) there are significantly fewer wind-dispersed species in areas of high total vegetation cover. These results may reflect successional patterns resulting from periodic flooding. Low areas close to the river flood more frequently and with greater intensity than areas farther from the river. Many pioneer species that establish in disturbed areas are wind-dispersed. Over successional time, pioneer species cede to more drought tolerant species that are predominantly animal-dispersed.     

Community structure of vascular epiphytes: a neutral perspective

Vascular epiphytes form a diverse group of almost 30 000 species, yet theory concerning their community structure is still largely lacking. We therefore employed the simplest models of biodiversity, (near-)neutral models, to generate hypotheses concerning their community structure. With recently developed tools for (near-)neutral models we analyzed species abundance data from many samples in Central and South America which we divided into four metacommunities (Mesoamerica, Central America, Amazonia and Paraná), where for each metacommunity we considered two subsets differing in dispersal syndrome: an animal-dispersed guild and a wind-dispersed guild. We considered three models differing in the underlying speciation mode. Across all metacommunities, we found observed patterns to be indistinguishable from patterns generated by neutral or near-neutral processes. Furthermore, we found that subdivision in different dispersal guilds was often supported, with recruitment limitation being stronger for animal-dispersed species than for wind-dispersed species. This is the first time that (near-)neutral theory has been applied to epiphyte communities. Future efforts with additional data sets and more refined models are expected to further improve our understanding of community structure in epiphytes and will have to test the generality of our findings.     

动物对松属植物种子的传播作用研究进展

松属植物约110种,根据种子传播方式可分为风传播松和动物传播松。风传播松占绝大多数,种子多具有适应风力的翅。动物传播松大约23种,都具有大、可食用、无翅或短翅的种子,无法借助风力传播。动物传播松的分布生境多为贫瘠的山地,而且多位于高海拔地区。目前已知9种松树的动物传播种类,其余14种可推测为动物传播。动物传播者包括鸦科鸟类和啮齿类动物,动物将获得的种子分散贮藏,未被重取的种子可能萌发,完成传播。动物传播是定向传播,微生境多适合种子萌发。啮齿类的传播距离可达数10 m,而鸦科鸟类的传播距离可达数公里。动物传播的松树会出现树丛和多树干现象,一般由同一贮点内贮藏的多粒种子萌发造成的。动物贮藏的种子大部分被重取,称传播后取食。一些具有大种子的风传播松在种子落地后,啮齿类和鸟类会再次埋藏而形成二次传播,可看做是一个单独的传播类型,即风-动物传播松。动物传播者与依赖传播松树之间可看作是互利共生关系。     

Effects of distinct types of disturbance on seed rain in the Atlantic forest of NE Brazil

In disturbed sites, some groups of seeds might be excluded from the seed rain due to their dispersal modes or seed size, and some groups might be successful as a result of disturbance effects. In the present study, we examined the seed rain in natural treefall gaps and in an area of regenerating forest following an accidental burning, which occurred 4 years before this study. Both of these disturbed areas were compared with nearby forest understorey. The number of seeds, number of species, and proportion of wind-dispersed seeds were compared between these disturbed and undisturbed areas. The treefall gaps have received lower numbers of seeds and species than the nearby understorey, but the number of wind-dispersed seeds did not differ between these areas. The lowest seed number observed in treefall gaps can be attributed to a lower number of animal-dispersed seeds, suggesting that animals may be avoiding treefall gap areas. A higher number of seeds and a lower number of species were observed in the burned area when compared to the adjacent understorey. The high number of small-sized seeds and of wind-dispersed seeds in the burned area was almost surely a consequence of the local production of the pioneer plants established after the burning. In this study, substantial differences were observed in the characteristics of the seed rain at disturbed sites, when compared with undisturbed understorey. However, these two distinct types of disturbance showed quite differing patterns, as treefall gaps received lower number of seeds while the burned area received a higher number of seeds, with a greater proportion of wind-dispersed seeds. The exception was for species richness, which was quite low at both these disturbed sites.     

Anthropogenic Halo Disturbances Alter Landscape and Plant Richness: A Ripple Effect

Although anthropogenic landscape fragmentation is often considered as the primary threat to biodiversity, other factors such as immediate human disturbances may also simultaneously threaten species persistence in various ways. In this paper, we introduce a conceptual framework applied to recreation landscapes (RLs), with an aim to provide insight into the composite influences of landscape alteration accompanying immediate human disturbances on plant richness dynamics. These impacts largely occur at patch-edges. They can not only alter patch-edge structure and environment, but also permeate into surrounding natural matrices/patches affecting species persistence–here we term these “Halo disturbance effects” (HDEs). We categorized species into groups based on seed or pollen dispersal mode (animal- vs. wind-dispersed) as they can be associated with species richness dynamics. We evaluated the richness of the two groups and total species in our experimental landscapes by considering the distance from patch-edge, the size of RLs and the intensity of human use over a six-year period. Our results show that animal-dispersed species decreased considerably, whereas wind-dispersed species increased while their richness presented diverse dynamics at different distances from patch-edges. Our findings clearly demonstrate that anthropogenic HDEs produce ripple effects on plant, providing an experimental interpretation for the diverse responses of species to anthropogenic disturbances. This study highlights the importance of incorporating these composite threats into conservation and management strategies.     

Water dispersal as an additional pathway to invasions by the primarily wind-dispersed tree <Emphasis Type="Italic">Ailanthus altissima</Emphasis>

Long-distance dispersal is a key process in biological invasions. Previous research has emphasized the role of nonstandard dispersal vectors, but consequences of a change in dispersal vector for the establishment of invasive plant species have received less attention. We analyzed how water-mediated dispersal rather than the more expected wind-mediated dispersal can affect the establishment of the invasive tree Ailanthus altissima in riparian corridors by changing the germination rate and velocity and by providing the option of a new pathway of vegetative propagation. We analyzed the potential of different types of propagules (fruits that have floated or been submerged, current- and second-year stem fragments) to establish new individuals after contact with water for 0, 3, 10, and 20 days. Length and type of seed contact with water led to divergent germination responses. Seeds that had floated for 3 days had an increased level of seed germination (87%), while a 20-day stay in water water-curbed germination to 32% compared to 53% in control. After floatation, the maximum number of emerged seedlings was achieved more than 3 weeks earlier than in all other treatments. In general, the germination was enhanced in floating compared to submerged fruits. Experiments with stem fragments revealed the option of a novel pathway for long-distance dispersal in river corridors: Except for stem fragments that floated for 20 days, 33–75% of buried stem fragments produced adventitious shoots, 10% also set roots. The results suggest that both generative and vegetative propagules of A. altissima can be dispersed at regional scales in river corridors. Hence, water as an additional dispersal vector is expected to enhance invasions by species with wind-dispersed seeds. Our findings suggest the importance of control of initial colonizations in riparian habitats and emphasize the need to include consequences of secondary dispersal when modeling the spread of invasive species.     

Early seed fall and seedling emergence: precursors to tropical restoration

We explore processes of seed immigration and seedling recruitment before an experimental rainforest restoration matures enough to affect either. Twenty-four 30 × 30-m plots were fenced in 12 ha of pasture in 2006. Seeds were collected in ninety-six 1-m⁻² seed traps; recruits were censused in ~12,000 m² in which establishment was allowed. We tested effects of distance from forest, living trees, and stumps of trees cut during site preparation on seed rain in 2007 and effects of these and soil depth on recruits through June 2008. Seed fall and recruitment were not correlated with distance to forest 90–400 m away, nor to living shade trees outside the 160 × 485-m experimental grid. Recruitment differed for animal- and wind-dispersed species in a topographically complex landscape. Recruitment of wind-dispersed species was random with respect to soil depth or distance to recent stumps. Recruitment of animal-dispersed species was multimodal; partial correlations with number of stumps within 30 m of plots were significant with soil depth held constant (P < 0.025), as were correlations of recruitment with soil depth with number of stumps held constant (P < 0.01). Animal-dispersed recruits were often not conspecifics of adults that had been cut, indicating a legacy of attraction by fruiting trees of animals bearing seeds from distant sources. Ecological implications are that recruitment in pastures released from grazing reflects a mix of widely scattered wind-dispersed pioneers and, where animal-dispersed trees exist, multi-modal and decidedly non-random recruitment of pioneer and later successional animal-dispersed trees from seed banks.     

Microsite and litter cover effects on seed banks vary with seed size and dispersal mechanisms: implications for revegetation of degraded saline land

Seed movements and fates are important for restoration as these determine spatial patterns of recruitment and ultimately shape plant communities. This article examines litter cover and microsite effects on seed availability at a saline site revegetated with Eucalyptus sargentii tree rows interplanted with 5?C6 rows of saltbush (Atriplex spp.). As litter accumulation decreases with increasing distance from tree rows, soil seed banks were compared between paired bare and litter-covered zones within three microsites; tree row, saltbush row closest to tree row and saltbush mid-row (middle row of saltbush between tree rows). Germinable seed banks of the four most abundant species with contrasting seed sizes and dispersal mechanisms were assessed to test the hypotheses that: (i) microsites with litter cover contain higher seed densities than bare areas, but that (ii) microsite and litter effects will vary depending on seed size and dispersal mechanisms. Overall, litter cover increased seed densities, however, litter effects varied with seed size, with no effect on small-seeded species and litter increasing densities of large-seeded species. Seed bank composition also differed between tree and shrub microsites due to differences in seed morphology and dispersal mechanisms. Water-dispersed species were unaffected by microsite but densities of wind-dispersed species, including Atriplex spp., were higher in saltbush microsites. Densities of wind-dispersed species also differed between the two saltbush microsites despite similar litter cover. Future plantings should consider row spacing and orientation, as well as the dimensions of seeding mounds and associated neighbouring depressions, to maximize litter and seed-trapping by microsites.     

Do Bird Perching Structures Elevate Seed Rain and Seedling Establishment in Abandoned Tropical Pasture?

Lack of seed dispersal has been shown to be a major factor limiting tropical forest recovery in abandoned pasture land. The goal of this work was to determine whether bird perching structures serve to enhance seed dispersal and seedling establishment in an abandoned pasture in Costa Rica. Two types of perching structures (crossbar and branch) were tested. Bird visitation rates were significantly higher on branch than on crossbar perches. The number of animal-dispersed seeds was significantly higher below branch perches than below crossbar perches or in open pasture. Despite differences in seed rain, percent cover of animal-dispersed plants and the number of seedlings of animal-dispersed plant species were similar below both perch types and in open pasture. Baiting perches with bananas did not increase either bird visitation rates or seed rain. These results suggest that, although bird perching structures increase seed dispersal, they do not overcome other barriers to tropical forest recovery such as seed predation and low seed germination.     

Wind effects on habitat distributions of wind-dispersed invasive plants across different biomes on a global scale: Assessment using six species

A number of widespread invasive plants are wind-dispersed, and wind may facilitate their dispersal and migration over a large distance. While wind is an important factor for seed dispersal and pollination, few studies have examined its potential to affect the habitat distribution of invasive plants over large spatial scales. We selected six of the world's worst invasive plants with wind-driving seed dispersal and pollination, and used wind speed as an indicator of wind. Environmental niche modelling was used to quantify the effects of wind on the habitat distribution of these invasive plants on a global scale and across 14 biomes. Wind had a negative effect on the habitat distribution of invasive plants in tropical and subtropical moist biomes, and a positive effect in Temperate Conifer Forests, Boreal Forests/Taiga, Temperate Grasslands, Savannas and Shrublands, and Montane Grasslands and Shrublands. We concluded that wind affected the habitat distribution of wind-dispersed invasive plants over a large scale, and this effect varied across different biomes. Thus, wind speed and biomes should be used as global monitoring indicators of invasion by wind-dispersed plants and wind speed variables should be included in the projection of habitat distributions of such invasive species when using ENM.