Distribution of social crab spiders in eucalypt forests

Abstract Social crab spiders (Thomisidae, Diaea) are found in Eucalyptus forests of varying latitude, altitude and species composition in southern Australia. Neither temperature nor rainfall differ between areas where social Diaea are found, suggesting that spiders have a preferred climatic range, and that they change altitudes at different latitudes to maintain their preferred range. In these areas, those Eucalyptus species that hosted Diaea had smaller leaves and fruit than eucalypts that did not, which suggests that the spiders may choose trees based on leaf morphology.     

Mass flowering of dipterocarp forests in the aseasonal tropics

At irregular intervals of 2 to 10 years the aseasonal tropical rain forests in west Malesia come into heavy mass flowering, followed by mast fruiting. During a heavy flowering almost half the mature individuals and over 80% of the canopy and emergent tree Species in a forest may flower. This involves over 200 tree species in a forest flowering over a short period of 3–4 months. The pollination needs during a mass flowering appears to be overcome in several ways. A rapid increase in the number of pollinators seems to occur in the forest. This is partly caused by the migration of pollinators from the fringes of the forest to forage on the superabundance of flowers. At the same time, some groups of plants which share common pollinators appear to reduce pollinator competition by flowering in interspecific sequence. Many members of the family Dipterocarpaceae have evolved sequential flowering too. They also share unique pollinators, common flower thrips which appear to build up rapidly in numbers by feeding and breeding on the millions of dipterocarp flower buds which are present several weeks before the flowering. The environmental cue for this irregular, but widespread mass flowering can be traced to a small dip of about 2° C below mean night-time temperature for 4 or 5 nights. The conditions for such temperature drops occur during El Nino events.     

Twenty years of understorey bird extinctions from Amazonian rain forest fragments: consistent trends and landscape-mediated dynamics

Aim We analysed presence/absence data for understorey bird species in rain forest fragments sampled from 1979 through 2001. Here we consider extinctions between 1992, when most fragments had been isolated for at least 8 years, and 2001. Our objectives were to determine whether high extinction rates documented soon after isolation continued through up to 20 years after isolation, and to examine fragment size and landscape effects on extinction. Location Biological Dynamics of Forest Fragments Project, near Manaus, Brazil. Methods Through 1992, birds were surveyed with standardized mist net sampling in ten 1‐ to 100‐ha fragments. We repeated the mist net protocol in 2000–01. We also added remote taping of the dawn chorus and tape playback surveys for species captured in 1991–92 but not in 2000–01. Results Between 1992 and 2001, 37 species went extinct in at least one fragment. As expected, extinction rate decreased with increasing fragment size. Over 30% of species went extinct in 1‐ha fragments, compared to about 5% in 100‐ha fragments. Extinction followed a predictable pattern: most species lost from 100‐ha fragments between 1992 and 2001 had already gone extinct in smaller fragments before 1992. Despite extinctions, fragments gained species between 1992 and 2001, apparently due to species moving through the developing second growth matrix. Fragments surrounded by old second growth had lower extinction rates than predicted based on fragment size alone. Main conclusions Sequential extinctions occurred for at least 20 years. Some additional species previously lost from smaller fragments may continue to go extinct in 100‐ha fragments. At the same time, species assemblages in 1‐ and 10‐ha fragments mostly reflect second‐growth dynamics by 20 years after isolation. High species loss predicted from the first few years after isolation has not occurred, almost certainly because of recolonization.     

A protocol for classifying regional dynamics,exemplified by using woodland birds in southeastern Australia

Abstract Communities of forest and woodland birds are usually studied intensively at only one or a few locations. This provides a perspective that perhaps emphasizes local phenomena at the expense of placing local dynamics in the context of processes operating at the landscape or regional scale. The present paper seeks to redress partially this imbalance by studying the dynamics of individual bird species among several habitat types (all Eucalyptus-dominated forests or woodlands) over the annual cycle. This regional-scale (250km), continental study reveals that species exhibit idiosyncratic dynamics of various kinds: restricted or more ubiquitous occupation of habitats and three forms of seasonal dynamics at the regional scale (resident, migrant and itinerant). By using this classificatory scheme, it becomes evident that the bird communities found in different habitats consist of diverse collections of strategists and that the level of diversity differs among habitat types. The difficulties that many field workers have had in reconciling their observations with community theory most likely reflect the underlying dynamism of bird communities, especially in the temperate regions on continents where seasonal fluxes are pronounced.     

Effects of flooding on a wetland bird community

The Lake Izunuma–Uchinuma was extensively flooded in 1998 and vast areas (approximately 200 ha) of rice fields were submerged for the first time since the land was reclaimed in 1963. When the numbers of birds in 1998 were compared with those in normal years (1995–1997), the numbers of black-crowned night herons (Nycticorax nycticorax L.), cattle egrets (Bubulcus ibis L.) and black kites (Milvus migrans Boddaert) increased during the flooding, and the numbers of ducks, especially dabbling ducks (seven species of 11 Anas spp.) were high even after the flooding, while the numbers of the little grebe Tachybaputus ruficollis Pallas were diminished by the flooding.     

城市化鸟类群落变化及其与城市植被的关系

持续而快速的城市化进程正在助长全球生物多样性的丧失,其中鸟类是城市生态系统的重要环节和城市生物多样性保护的重点目标,同时也是研究的热点内容。从城市环境变化压力下,鸟类群落组成与结构、空间分布和繁殖营巢方式的改变分析,重点介绍了支持城市地区鸟类多样性的植物环境因素与影响机制的最新研究成果。结果表明：1）城市中的植被和绿色空间为城市鸟类提供生存空间和食物资源,是城市鸟类最主要的栖息地。2）保留原生乡土植物和大型树木的地区能支持更丰富的鸟类物种。3）植被的结构和盖度对鸟类群落有显著影响。林冠覆盖率增加,复杂的垂直空间和多样的植物种类的组合产生各种不同类型的植物空间和栖息地类型,吸引不同的鸟类物种,相应地也会导致更丰富的鸟类群落。总之,保持和加强城市中植物环境良好和稳定是保护城市生物多样性的有效手段。据此,提出城市环境与鸟类群落关系研究的未来发展方向,指出了其在鸟类多样性保护和城市可持续发展等领域的应用前景。     

Seasonality of canopy invertebrate communities in eucalypt forests of eastern and western Australia

Abstract Chemical knockdown procedures were used to sample canopy arthropods at 3 month intervals over 1 year at two sites, one in eastern Australia and the other in western Australia. Samples were taken from narrow-leaved ironbark, Eucalyptus crebra, and grey box, Eucalyptus moluccana, in the east and from jarrah, Eucalyptus marginata, and marri, Eucalyptus calophylla, in the west. Arthropods were more abundant on trees in eastern Australia and exhibited different seasonal patterns from those in the west. Members of different functional groups exhibited different seasonal patterns, with some herbivorous groups responding to times of leaf production, decomposers and fungus feeders responding to high moisture availability, and predators/parasites responding to the abundance of food items. Seasonal variability was slightly higher in the west, possibly reflecting the greater seasonal amplitude in rainfall. In the eastern forest, proportionately more taxa peaked in spring or summer and declined to minimum numbers in winter. In the western forest several taxa attained peak numbers in autumn, winter or spring, while others declined to minimum values in winter or summer. The phenological patterns of canopy arthropods appear to be linked to the condition of the host plant and/or to climatic factors. Comparison of the western Australian data to those from a second year of sampling at a time when rainfall was greater and fell later into the season indicated that variability in arthropod numbers between years can be as great as that between seasons. Implications of the variability in seasonal and annual patterns of canopy invertebrate communities are discussed in relation to the need for long-term sampling and in relation to evaluating the impact of disturbance on forest communities.     

The structure and organisation of an Amazonian bird community remains little changed after nearly four decades in Manu National Park

Documenting patterns of spatiotemporal change in hyper-diverse communities remains a challenge for tropical ecology yet is increasingly urgent as some long-term studies have shown major declines in bird communities in undisturbed sites. In 1982, Terborgh et al. quantified the structure and organisation of the bird community in a 97-ha. plot in southeastern Peru. We revisited the same plot in 2018 using the same methodologies as the original study to evaluate community-wide changes. Contrary to longitudinal studies of other neotropical bird communities (Tiputini, Manaus, and Panama), we found little change in community structure and organisation, with increases in 5, decreases in 2 and no change in 7 foraging guilds. This apparent stability suggests that large forest reserves such as the Manu National Park, possibly due to regional topographical influences on precipitation, still provide the conditions for establishing refugia from at least some of the effects of global change on bird communities.     

破碎化次生林斑块面积及栖息地质量对繁殖鸟类群落结构的影响

于1998～2000年夏季。运用GPS定位系统确定了12块面积范围为6．5～112．8hm。的彼此隔离的森林斑块。比较了斑块面积和栖息地质量对繁殖鸟类群落结构的影响。结果表明：不同面积斑块中繁殖鸟类的群落结构有所差异。各斑块所容纳的繁殖鸟类的物种数从4种到26种不等。鸟类物种数随着斑块面积的增大而增多。不同鸟类对斑块面积的反应并不相同,耐边缘种偏爱面积较小的斑块。而非边缘种偏爱在大面积的斑块中繁殖。斑块栖息地质量也是影响鸟类群落结构的重要因素,质量好的斑块包容的鸟类物种较多。鸟类物种丰富度与斑块质量的相关性(R2=0．67)小于与斑块面积的相关性(R2=0．88)。各斑块中的鸟类群落结构在不同年份间比较相似。栖息地破碎化不但缩小了栖息地面积。同时也不同程度地降低了栖息地的质量。从而消极地影响着鸟类群落结构的稳定性和鸟类的物种多样性。     

Seasonal changes in bird assemblages of coastal woodlands in east-central Argentina

We studied seasonal variation in bird assemblages during two years in the coastal woodlands of the reserve, 'El Destino', Buenos Aires Province, Argentina. Higher bird density was recorded during spring, and lower one during autumn, but species richness did not show changes during the annual cycle. Seasonal variation in abundance and species composition was recorded for the frugivore-insectivore and the granivore guilds, however, not for the insectivores. As winter is not harsh, insectivorous species might not be faced with food shortage. In contrast, the abundance of frugivorous-insectivorous and granivorous species appeared to be related with fluctuations in their food resources.     

Connectivity with primary forest determines the value of secondary tropical forests for bird conservation

Species extinctions caused by the destruction and degradation of tropical primary forest may be at least partially mitigated by the expansion of regenerating secondary forest. However, the conservation value of secondary forest remains controversial, and potentially underestimated, since most previous studies have focused on young, single‐aged, or isolated stands. Here, we use point‐count surveys to compare tropical forest bird communities in 20–120‐year‐old secondary forest with primary forest stands in central Panama, with varying connectivity between secondary forest sites and extensive primary forest. We found that species richness and other metrics of ecological diversity, as well as the combined population density of all birds, reached a peak in younger (20‐year‐old) secondary forests and appeared to decline in older secondary forest stands. This counter‐intuitive result can be explained by the greater connectivity between younger secondary forests and extensive primary forests at our study site, compared with older secondary forests that are either (a) more isolated or (b) connected to primary forests that are themselves small and isolated. Our results suggest that connectivity with extensive primary forest is a more important determinant of avian species richness and community structure than forest age, and highlight the vital contribution secondary forests can make in conserving tropical bird diversity, so long as extensive primary habitats are adjacent and spatially connected.Abstract in Spanish is available with online material.     

Role of magpie in bird community formation in secondary forest

We analyzed a bird community in a secondary forest and the results show that the magpie was one of the key groups in the secondary forest. The key group is identified based on the nests used by other birds at a rate of 25%–40.17%. The size of the community is different and the number of these key groups is not certain. __________ Translated from Journal of Northeast Normal University (Natural Science Edition), 2006, 38 (3): 644-651 [译自: 东北师大学报(自然科 学版)]     

Role of magpie in bird community formation in secondary forest

We analyzed a bird community in a secondary forest and the results show that the magpie was one of the key groups in the secondary forest. The key group is identified based on the nests used by other birds at a rate of 25%-40.17%. The size of the community is different and the number of these key groups is not certain.     

城市公园生境类型对鸟类群落的影响

2011年12月—2012年11月,在上海世纪公园和滨江森林公园对鸟类群落和植物群落进行调查,通过对12个植被变量进行主成分分析,将两个公园分为8种不同的生境类型。结果表明:2个公园生境构成存在显著差异,滨江森林公园灌木层植物发达的生境(Habitat with developed shrub layer,S型)以及灌木层和地被层植物都发达的生境(Habitat with developed tree layer and shrub layer,T+S型)数量显著多于世纪公园,世纪公园地被层发达的生境(Habitat with developed ground cover layer,G型)以及乔木层和地被层植物都发达的生境(Habitat with developed tree layer and ground cover layer,T+G型)数量显著多于滨江森林公园。世纪公园不同生境中鸟种数差异显著,而滨江森林公园中差异不显著。2个公园有24种共有鸟种,对共有鸟种生境利用率的配对t检验结果表明,滨江森林公园鸟类生境利用率显著高于世纪公园。对2个公园共有生境类型中鸟种数进行分析,发现滨江森林公园鹟科(Muscicapidae)鸟类种数显著大于世纪公园。根据以上结果,上海城市公园不同生境类型对鸟类群落结构存在显著影响。因此,建议在规划和建设大型城市公园时,应构建植被分层结构复杂的生境,多样化种植各类乔木,林下多样化搭配灌木。在保留供游客休憩草坪区域的同时种植各类草本植物,以此提高鸟类生境利用率,增加城市公园的鸟类多样性。     

Consequences of forest fragmentation for the dynamics of bird populations: conceptual issues and the evidence

This paper reviews the consequences of forest fragmentation for the dynamics of bird populations. Owing to high mobility and large home ranges, birds usually perceive fragmented forests in a finegrained manner, i.e. embrace several forest fragments in functional home ranges. On a regional scale, however, coarse-grained clusters of fine-grained fragments (hierarchical fragmentation may sub-divide bird populations into isolated demes, which enter a domain of metapopulation dynamics. Distinctions are made between pure distance-area or population-level effects and more indirect community-level effects due to changes in landscape composition. Distance-area effects, such as insularization and decreasing fragment size, directly prevent dispersal and reduce population size. Landscape effects, such as reduced fragment-matrix and interior-edge ratios, increase the pressure from surrounding predators, competitors, parasites and disease. In short, forest fragmentation can be viewed as a two-step process. Initially, fine-grained fragmentation triggers distance-area and landscape effects on a local scale, which in turn, results in a range retraction of a population to non-fragmented or less fragmented parts of a region. At a certain point, non-fragmented areas become so widely spaced out that regional distance-area effects come into operation, giving rise to metapopulation dynamics. Although few bird metapopulations have yet been documented, metapopulation dynamics probably is a common characteristic of bird populations confined to 'hierarchical' fragmented forests.