Disturbance effects on diversity of epiphytes and moths in a montane forest in Ecuador

We sampled the diversity of epiphytes (lichens, bryophytes, vascular plants) and moths (Geometridae, Arctiidae) in mature and recovering forest and in open vegetation in the montane belt in Ecuador. No uniform pattern of change in species richness was detected among the different taxonomic groups with increasing disturbance. Species richness of epiphytic bryophytes and vascular plants declined significantly from mature forest towards open vegetation. In contrast, species richness of epiphytic lichens did not change with increasing forest alteration, while that of geometrid moths was significantly higher in recovering forest compared with mature forest and open habitats. Arctiidae were significantly more species-rich in recovering forest and open vegetation than mature forest. Hence, for some organisms, modified habitats may play an important role for biodiversity conservation in the Andes, whereas others suffer from habitat disturbance. However, trends of changes in species composition following deforestation were surprisingly concordant across most studied epiphyte and moth taxa.     

Seedling establishment of vascular epiphytes on isolated and enclosed forest trees in an Andean landscape, Ecuador

The impact of human disturbance on colonisation dynamics of vascular epiphytes is poorly known. We studied abundance, diversity and floristic composition of epiphyte seedling establishing on isolated and adjacent forest trees in a tropical montane landscape. All vascular epiphytes were removed from plots on the trunk bases of Piptocoma discolor. Newly established epiphyte seedlings were recorded after 2 years, and their survival after another year. Seedling density, total richness at family and genus level, and the number of families and genera per plot were significantly reduced on isolated trees relative to forest trees. Seedling assemblages on trunks of forest trees were dominated by hygrophytic understorey ferns, those on isolated trees by xerotolerant canopy taxa. Colonisation probability on isolated trees was significantly higher for plots closer to forest but not for plots with greater canopy or bryophyte cover. Seedling mortality on isolated trees was significantly higher for mesophytic than for xerotolerant taxa. Our results show that altered recruitment can explain the long-term impoverishment of post-juvenile epiphyte assemblages on isolated remnant trees. We attribute these changes to a combination of dispersal constraints and the harsher microclimate documented by measurements of temperature and humidity. Although isolated trees in anthropogenic landscapes are considered key structures for the maintenance of forest biodiversity in many aspects, our results show that their value for the conservation of epiphytes can be limited. We suggest that abiotic seedling requirements will increasingly constitute a bottleneck for the persistence of vascular epiphytes in the face of ongoing habitat alteration and atmospheric warming.     

Edge effects on epiphytic communities in a Mediterranean Quercus pyrenaica forest

Question: What are the edge effect responses of epiphytic lichen communities in Mediterranean Quercus pyrenaica forest? Location: Central Spain. Methods: We established ten transects perpendicular to a road dissecting a well conserved remnant of Q. pyrenaica forest into two sections. Transects extended from the forest/road edge to 100 m into the forest. Data were collected from seven plots in each transect at different distances from the edge. Variables were grouped into stand scale variables (distance to edge, number of trees per plot, mean diameter per plot, irradiance) and tree scale variables (diameter and height of sampled trees, aspect of the sampled square and relative height of the square). We used General Mixed Linear Models and constrained ordination techniques to test the hypothesis that the spatio‐temporal heterogeneity of light and water controls the occurrence of lichens and bryophytes along the edge‐interior gradient in the Q. pyrenaica forest. Results: Microclimatic parameters vary in a non‐linear way; edge and interior stands showed the most divergent and extreme values. Although the micro‐environment within Mediterranean forests is heterogeneous, interior conditions are apparently suitable for the performance of some specific forest epiphytes. Consequently, species richness does not show significant differences along the gradient. Total epiphytic cover increases towards the forest interior, but distance to the edge together with other predictors at the tree scale (aspect and height of the square) are the most relevant predictors for the composition and structure of these communities. Conclusions: Composition and structure of epiphytic communities in a Mediterranean semi‐deciduous forest are affected by the edge between the forest and the road constructed. Since some extremely rare lichens only occur at interior stands, the conservation of these threatened elements requires urgent conservation measures because well preserved and unmanaged forests in the Mediterranean region are very rare.     

Tree and stand-scale factors affecting richness and composition of epiphytic bryophytes and lichens in deciduous woodland key habitats

Conservation and sustainable forestry are essential in a multi-functional landscape. In this respect, ecological studies on epiphytes are needed to determine abiotic and biotic factors associated with high diversity. The aim of the present study was to evaluate relative sensitivity of conservation targets (epiphytic bryophytes and lichens) in relation to contrasting environmental variables (tree species, tree diameter at breast height, bark crevice depth, pH, tree inclination, pH, forest stand age, area and type) in boreo-nemoral forests. The study was conducted in Latvian 34 woodland key habitat (WKH) boreo-nemoral forest stands. Generalized linear mixed models and canonical correspondence analysis showed that tree species and tree bark pH were the most important variables explaining epiphytic bryophyte and lichen composition and richness (total, Red-listed, WKH indicator species). Forest stand level factors, such as stand size and habitat type, had only minor influence on epiphytic species composition and richness. The results of the present study indicate a need to maintain the diversity of tree species and large trees, particularly Acer platanoides, Carpinus betulus, Fraxinus excelsior, Populus tremula, Tilia cordata, Ulmus glabra and Ulmus laevis in conservation of epiphytic bryophyte and lichen communities in the future.     

Trends in diversity and abundance of obligate epiphytic bryophytes in a highly managed landscape

Although forest stands represent 47% of the total land area in Europe, alterations to the forest habitat through logging and plantation of exotic trees has led to significant changes in forest biocenoses. Due to their peculiar biology and life history, epiphytic bryophytes, which include a number of species of high conservation value, are especially concerned. Ordinal logit regression was used to test whether trends in diversity and abundance of obligate epiphytic bryophytes are explained by forest cover and spruce plantation and determine specific optima and degree of reliance to these factors at the landscape scale. Spruce plantations had a negative impact on both species diversity and abundance. Although large forest patches were important for a set of species exclusively or more frequently occurring under the forest cover, the abundance of a number of species previously identified as woodland bryophytes decreased or was uncorrelated with increasing forest cover. Furthermore, the species pool adapted to edge-related abiotic conditions was important. The global epiphytic diversity did consequently not decrease with decreasing forest cover at the landscape scale. If large forest patches are important for the conservation of a set of species exclusively or more frequently occurring under the forest cover, the conservation of epiphytic bryophytes thus also involves the conservation of pioneer trees in open landscapes. A series of management measures, which may help maximize the species diversity and probability of occurrence of key-species of high conservation interest, are proposed.     

Bole epiphytic bryophytes on <Emphasis Type="Italic">Lithocarpus xylocarpus</Emphasis> (Kurz) Markgr. in the Ailao Mountains,SW China

Epiphytic bryophytes growing on Lithocarpus xylocarpus (Kurz) Markgr. trunks of different diameter classes in primary (132 plots) and secondary (84 plots) Lithocarpus forests in the Ailao Mountains, SW China, were surveyed and analyzed to determine species composition and richness, and to identify environmental variables that may affect it. Among the 65 species (belonging to 32 genera, 19 families) found, 28 occurred in both forests, with Syrrhopodon gardneri (Hook.) Schwaegr. predominanting. Species richness and total coverage in primary forest were significantly higher than in secondary forest. We suggest that a period of perhaps much more than 110 years is necessary for the recovery of epiphytic bryoflora in montane forest of SW China. Fan, turf, and smooth mat are the most important life forms, with high occurrences in both forests. The life form composition of epiphytic bryophytes is determined mainly by microhabitat and host age. Tree age, the presence of primary forest, bark pH, and plot exposure are the environmental variables that have significantly influenced the composition of epiphytic bryophytes. Tree age explained most variations in epiphytic bryoflora. Bark pH is another important parameter that significantly influenced the epiphytic bryophyte community, but seemed indirectly correlated with tree age. Primary forest is a favorable habitat for epiphytes, due mainly to its diversified canopy structure and the presence of large diameter hosts. Moisture-laden southwest trade winds and forest structure could differentiate microclimate and impel a distinct composition of epiphytes in windward and leeward exposures.     

Responses of the distribution of four epiphytic cyanolichens to habitat changes in subtropical forests

 蓝藻地衣是附生植物类群的重要组成部分, 在森林生态系统的环境监测和养分循环中发挥着重要作用。该研究在云南哀牢山亚热带森林系统的2种原生和6种次生森林群落中, 以粉缘绵毛衣(Leioderma sorediatum)、天蓝猫耳衣(Leptogium azureum)、网肺衣(Lobaria retigera)和双缘牛皮叶(Sticta duplolimbata) 4种常见蓝藻地衣为对象, 共设立120个样地, 调查了它们在3 600株树木0–2 m树干上的分布, 探讨其分布特征及与森林类群、宿主种类以及林龄等生境因子的关系。研究发现4种蓝藻地衣在森林群落间的分布模式明显不同。除双缘牛皮叶的盖度和频度在原生苔藓矮林中最高外, 其他3种蓝藻地衣的最高值均出现于次生林如厚皮香(Ternstroemia gymnanthera)林和滇山杨(Populus bonatii)林中; 而哀牢山地区广布的原生木果柯(Lithocarpus xylocarpus)林中, 4种蓝藻地衣极为少见。4种地衣都能生长于10多个树种上, 但明显表现出对厚皮香、滇山杨和硬壳柯(Lithocarpus hancei)等树种的偏好性, 以及对小花山茶(Camellia forrestii)等的排斥性。森林群落的林龄、胸径、最大胸径、林冠开阔度、基面积、树木密度和树种多样性等因子的变化均对4种附生蓝藻地衣的分布产生重要影响, 但在景观尺度上影响程度相对较小, 在不同森林群落内部却有各自的重要作用。其中, 林龄、林冠开阔度和宿主胸径是影响蓝藻地衣分布的最重要的生境因子。     

云南石林喀斯特地区半湿润常绿阔叶林附生植物的初步研究

对云南石林喀斯特山地原生植被——半湿润常绿阔叶林中附生植物的组成、生物量以及附生植物持水量等进行研究,结果表明该区森林林木附生植物种类相对较少,只有8科9种附生维管束植物和5种苔藓植物,而林内岩石表面则有石附生维管束植物16科17种,苔藓植物3种,两种不同生境附生植物的相似性系数为0.5。相同取样面积(400cm2)条件下,岩石表面附生植物平均生物量(11.7g)比林木表面(4.9g)的高。附生植物一次持水量为自身干重的5.5~9.7倍。     

Epiphytic lichens and bryophytes of forest ecosystems in Tuscany (Central Italy)

The distribution of epiphytic bryophytes and lichens on three species of trees (Quercus ilex, Quercus cerris and Fagus sylvatica, representing the forest ecosystems of central Italy at low, medium and high elevations, respectively) was examined with respect to host specificity and habitat differences. Although most species were host-specific, the results suggested that habitat characteristics are more important than phorophyte properties in determining the distribution of lichens and bryophytes. Factors affecting the diversity of the epiphytic flora were different for lichens and bryophytes. In the case of lichens, climatic parameters and forest monospecificity were important factors, whereas tree cover (i.e. shade) and to a certain extent the number of available trees seemed more important for bryophytes.     

影响广东黑石顶树附生苔藓分布的环境因子

通过对广东省黑石顶自然保护区内5个2500 m2样地内树附生苔藓的调查及有关环境因子的测定,研究了树附生苔藓的分布格局及其与环境因子的关系.树附生苔藓在不同高度的分布存在一定梯度,20 cm高处树附生苔藓的种类数与盖度均大于60 cm及更高处,且其群落优势种的数量组成与后者存在较大差异.不同树种附生苔藓盖度和种数差异较大.基于附生苔藓植物的盖度进行DCA排序及聚类分析将树种分成四组,马尾松(Pinus massoniana)因具有两种特有的网藓(巴西网藓Syrrhopodon prolifer和鞘刺网藓S.armatus)单独一组,福建青冈(Quercus chungii)亦与其余各种的差异均较大,形成一组,其余阔叶树种根据其所处的森林类型分成两组,针阔叶混交林内的阔叶树种和次生阔叶林内的阔叶树种各形成一组.对环境因子及树皮含水量和pH的分析显示,垂直梯度上空气湿度的差异可能是造成附生苔藓在不同高度分布差异的主要影响因子之一,不同树种附生苔藓的差异在一定程度上受树皮pH的影响,而与树皮含水量无关.同一树种上树附生苔藓的分布又在一定程度上受森林类型的影响.     

林冠附生植物生态学研究进展

林冠附生植物及其枯死存留物是构成山地湿性森林生态系统中生物区系、结构和功能的重要组分。由于在林冠攀爬技术上的限制,过去对林冠附生植物在生态系统结构和功能过程中的作用未能引起足够的重视。近20年来,随着对林冠生物多样性及其在生态系统功能过程影响的认识和研究技术上的提高,对林冠附生生物的研究已逐步从个体水平转移到系统水平上。有关林冠附生植物多样性、生物量及其生态学效应已成为近年来国际上新兴研究领域——“林冠学”的研究热点之一。许多研究表明,林冠附生植物在生态系统水平上的交互作用比它们的解剖、形态和生理特征更为重要。国外大量的研究结果表明,林冠是一个适合于许多生物种类生存的场所,其数量比想象的更为丰富。在全球范围内估计有29 500余种附生植物,其中维管束附生植物的种类高达24 000种,约占总维管束植物种类的10%。林冠附生物的生物量在世界各地森林中存在较大的差异,其范围在105~44 000 kg·hm^-2之间,其中在一些热带和温带天然老龄林中林冠附生物的生物量超过了宿主林木的叶生物量。林冠附生植物还具有较大的叶面积指数(LAI)。林冠附生物丰富的物种组成、较高的生物量、独特的生理形态特征以及它们分布于森林与大气相互作用的关键界面,使得它们在生态系统物种多样性形成及其维持机制、养分和水分循环、指示环境质量等方面具有重要的作用。林冠附生植物及其枯死残留物具有较强的能力吸收雨水和空气中的营养物质,在林冠层中形成一个潮湿的环境促进氮固定,林冠附生植物群落还能为生存于林冠的其它生物(如鸟类、哺乳动物、两栖动物、爬行动物和昆虫等)提供食物和栖息场所。林冠附生植物的生长发育与分布格局除与宿主有关外,还受到环境因素(气候、地形、微生境条件等)和人为干扰的影响。由于世界各地森林类型多样和环境条件各异,目前国际上有关附生物的研究仍十分活跃,建立了林冠研究网络,研究不同类型森林中附生植物及其枯死残留物的动态及其与群落特征、环境因子的数量关系,探讨、交流和发展有效的标准测量方法和技术是该领域研究的主要内容。国内对林冠附生植物生态学的研究刚刚起步,有待于今后加强该领域的研究。     

The effects of stand structure on ground-floor bryophyte assemblages in temperate mixed forests

The effect of tree species composition, stand structure characteristics and substrate availability on ground-floor bryophyte assemblages was studied in mixed deciduous forests of Western Hungary. Species composition, species richness and cover of bryophytes occurring on the soil and logs were analysed as dependent variables. The whole assemblage and functional groups defined on the basis of substrate preference were investigated separately. Substrate availability (open soil, logs) was the most prominent factor in determining species composition, cover and diversity positively, while the litter of deciduous trees had a negative effect on the occurrence of forest floor bryophytes. Besides, bryophyte species richness increased with tree species and stand structural diversity, and for specialist epiphytic and epixylic species log volume was essential. Sapling density and light heterogeneity were influential on bryophyte cover, especially for the dominant terricolous species. Many variables of the forest floor bryophyte community can be estimated efficiently by examining stand structure in the studied region. Selective cutting increasing tree species diversity, stand structural heterogeneity and dead wood volume can maintain higher bryophyte diversity in this region than the shelter-wood system producing even-aged, monodominant, structurally homogenous stands.     

Diversity and similarity of butterfly communities in five different habitat types at Tam Dao National Park, Vietnam

Diversity and similarity of butterfly communities were assessed in five different habitat types (from natural closed forest to agricultural lands) in the mountains of Tam Dao National Park, Vietnam for 3 years from 2002 to 2004. The line transect count was used to record species richness and abundance of butterfly communities in the different habitat types. For each habitat, the number of species and individuals, and indices of species richness, evenness and diversity of butterfly communities were calculated. The results indicated that species richness and abundance of butterfly communities were low in the natural closed forest, higher in the disturbed forest, highest in the forest edge, lower in the shrub habitat and lowest in the agricultural lands. The indices of species richness, evenness and diversity of butterfly communities were low in agricultural lands and natural closed forest but highest in the forest edge and shrub habitats. The families Satyridae and Amathusiidae have the greatest species richness and abundance in the natural closed forest, with a reduction in their species richness and abundance from the natural closed forest to the agricultural lands. Species composition of butterfly communities was different among five different habitat types (40%), was similar in habitats outside the forest (68%) and was similar in habitats inside the forest (63%). Diversity and abundance of butterfly communities are not different between the natural closed forest and the agriculture lands, but species composition changed greatly between these habitat types. A positive correlation between the size of species geographical distribution range and increasing habitat disturbance was found. The most characteristic natural closed forest species have the smallest geographical distribution range.     

Effects of Multiple Disturbances (Fire and Hurricane) on Epiphyte Community Dynamics in a Subtropical Forest,Florida, U.S.A.1

We addressed the interacting effects of a natural large–scale fire and a subsequent major hurricane on relative positions of epiphytes in a subtropical forest. In Everglades National Park, subtropical hammocks (hardwood tree “islands”; burned and unburned) during the Ingraham Fire (1989) were surveyed for trees and epiphytic bromeliads (Tillandsia spp.) one year before, as well as one and five years after, Hurricane Andrew (1992). We measured trees (species, diameter, and status [alive/dead]) and epiphytes (species, height, host tree characteristics, substrate life status, and density). The fire decreased the height of epiphytes during the hurricane because branches and bark of trees killed by the fire were unstable epiphyte substrates in the high winds. Proportions of epiphytes on Quercus virginiana were equally increased after the hurricane in both unburned and burned hammocks; the large size and bark characteristics resulted in greater proportional survival of epiphytes on this species. During the five years following the hurricane, changes in the distributions of epiphytes generally were toward pre–hurricane distributions, but recovery was faster in unburned than burned hammocks. We conclude that disturbances that kill trees are likely to amplify the vertical reduction of epiphytes during a subsequent hurricane and that effects of a single disturbance on plant populations can be influenced by the disturbance history of the system, including different types of disturbances.     

Specific leaf area as a superior predictor of changes in field layer abundance during forest succession

Question : How accurately can a suite of suggested functional traits predict plant species response to succession from semi‐open woodland to closed deciduous canopy forest? Location : Southeastern Sweden. Methods : Abundance of 46 field‐layer plant species in a temperate deciduous forest, measured as frequency of occupied plots, was estimated in 1961, 1970 and 2003. Abundance change over time across species was tested for correlations with functional traits and literature information on habitat preference. Results : Increase in abundance was positively correlated with specific leaf area (SLA), weakly negatively correlated with seed mass and not significantly correlated with plant height or start, peak and length of the flowering period. Change in abundance was correlated with the Ellenberg light indicator value, whereas no correlations were found with Ellenberg values for nitrogen, calcium and moisture, or forest preference according to the literature. Conclusions : SLA was a better predictor of how field layer plants responded to succession from semi‐open woodland to closed canopy forest than empirically‐derived measures of habitat preference. The same holds for SLA in relation to seed size, indicating that interactions in the established life‐cycle phase are more important than the recruitment phase for species response to succession.     

Spatial variation and biogeography of sand forest avian assemblages in South Africa

Aim To examine biogeographical affiliations, habitat‐associated heterogeneity and endemism of avian assemblages in sand forest patches and the savanna‐like mixed woodland matrix. Location Two reserves in the Maputaland Centre of Endemism (MC) on the southern Mozambique Coastal Plain of northern KwaZulu‐Natal, South Africa. Methods Replicated surveys were undertaken in each of the two habitat types in each reserve, providing species abundance data over a full year. Vegetation structure at each of the survey sites was also quantified. Differences between the bird assemblages and the extent to which vegetation structure explained these differences were assessed using multi‐variate techniques. Biogeographical comparisons were based on species presence/absence data and clustering techniques. Results Bird assemblages differed significantly between habitats both within a given reserve and between reserves, and also between reserves for a given habitat. Differences in vegetation structure contributed substantially to differences between the avian assemblages. Of the four species endemic to the MC, three (Neergaard’s sunbird, Rudd’s apalis, and Woodward’s batis) were consistently present in sand forest. The fourth (pink‐throated twinspot) preferred mixed woodland. None of these endemic species was classed as rare. In the biogeographical analysis, both the sand forest and the mixed woodland bird assemblages were most similar to bird assemblages found in the forest biome or the Afromontane forest biome, depending on the biome classification used. Main conclusions The close affinities of sand forest and mixed woodland assemblages to those of the forest biome are most likely due to similarities in vegetation structure of these forests. Bird assemblages differ between the sand forest and mixed woodland habitats both within a given reserve and between reserves, and also between reserves for a given habitat. These differences extend to species endemic to the MC. Thus, conservation of sand forest habitat in a variety of areas is necessary to ensure the long‐term persistence of the biota.     

Ant assemblages in isolated trees are more sensitive to species loss and replacement than their woodland counterparts

Isolated trees possess an arthropod assemblage different to that found in woodland trees. While isolated trees become an increasingly dominant part of many landscapes, with ‘off reserve’ habitat conservation potential, we know little about the drivers of their assemblage structure. While sampling bimonthly for 12 months in the seasonally dry tropics of Mexico, we characterized the ant species most likely to occupy isolated trees in comparison to small woody patches (‘matorral’; 0.13–0.74 ha), and examined the influence of environmental variables on the respective ant assemblages at both canopy and ground level. Isolated trees possessed a predictable ant assemblage: when compared to the woodland patches, isolated trees were characterised by a lack of specialised arboreal species and an increase in generalised terrestrial species reaching the canopy. Arboreal woodland ant species were as affected by tree isolation as the terrestrial woodland ant fauna. Ant assemblages at isolated trees correlated with a series of microenvironmental (microclimate and biophysical) variables, but this was not the case for the ant assemblages in woodlands. This suggests that at very small habitat sizes (e.g., isolated trees), microenvironment influences assemblage composition by favouring more environmentally tolerant or opportunistic species. Although we were unable to identify alternative variables (e.g., patch area, connectivity) which correlated with assemblage composition in larger habitat patches, it appears that in such patches, local microenvironment is less closely associated with assemblage structure, and variables such as patch and landscape configuration become increasingly important. In a practical sense, micro-habitat restoration aimed at augmentation of vegetation surrounding isolated trees may therefore be an effective means of increasing matrix habitat quality and increasing the partitioning of the arboreal and terrestrial faunas, thereby conserving a broader range of species. More generally, movement of matrix species into habitat patches appears to apply universally over a range of scales and taxa, and provides a distinct contrast to the predictions based on the Theory of Island Biogeography.     

Epiphytic ferns and bryophytes of Tasmanian tree‐ferns: A comparison of diversity and composition between two host species

Abstract Ferns, bryophytes and lichens are the most diverse groups of plants in wet forests in south‐eastern Australia. However, management of this diversity is limited by a lack of ecological knowledge of these groups and the difficulty in identifying species for non‐experts. These problems may be alleviated by the identification and characterization of suitable proxies for this diversity. Epiphytic substrates are potential proxies. To evaluate the significance of some epiphytic substrates, fern and bryophyte assemblages on a common tree‐fern species, Dicksonia antarctica (soft tree‐fern), were compared with those on a rare species, Cyathea cunninghamii (slender tree‐fern), in eastern Tasmania, Australia. A total of 97 fern and bryophyte species were recorded on D. antarctica from 120 trunks at 10 sites, and 64 species on C. cunninghamii from 39 trunks at four of these sites. The trunks of C. cunninghamii generally supported fewer species than D. antarctica, but two mosses (particularly Hymenodon pilifer) and one liverwort showed significant associations with this host. Several other bryophytes and epiphytic ferns showed an affinity for the trunks of D. antarctica. Species assemblages differed significantly between both sites and hosts, and the differences between hosts varied significantly among sites. The exceptionally high epiphytic diversity associated with D. antarctica suggests that it plays an important ecological role in Tasmanian forests. Evidently C. cunninghamii also supports a diverse suite of epiphytes, including at least one specialist species.     

Host trait preferences and distribution of vascular epiphytes in a warm-temperate forest

To illustrate the ecological factors and process leading to the observed diversity patterns of vascular epiphytes, we examined the effect and importance of host tree traits on epiphyte richness and spatial aggregation of epiphytes. The study was conducted in warm-temperate forest in Japan. The recorded host traits were diameter, height, species, habitat topography, and growth rate, and we analyzed the effects and importance of these traits on three species groups: total epiphytic species, epiphytic orchid species, and epiphytic pteridophyte species. Diameter and species of host trees had the greatest influence on epiphytes and their magnitudes were roughly similar in all species groups. Growth rate and topography were less important than host size and species. Growth rate had a negative effect on all three groups, and topography was important for pteridophytes. Epiphyte richness did not exhibit clear spatial aggregation. Our results suggest that size, stability, and quality of the host are equally important in determining epiphyte colonization.     

Habitat fragmentation,EFN‐bearing trees and ant communities: Ecological cascades in Atlantic Forest of northeastern Brazil

Habitat fragmentation has a marked impact on the functional composition of tropical forest tree assemblages, and such change is likely to cascade through other trophic levels. Here, we investigate how habitat fragmentation affects extrafloral nectary (EFN)‐bearing plants and ant functional groups known to attend EFNs in a fragmented landscape of the Atlantic Forest. Extrafloral nectary‐bearing trees were identified in 50 0.1‐ha plots located in forest fragments, edge and interior patches. Ants were surveyed in 30 1‐m² litter samples in each of 17 forest fragments and in forest interior. Extrafloral nectary‐bearing plants accounted for 19.9% of individuals and 10.5% of species and included both pioneer and shade‐tolerant species similarly rich in the three habitat types. However, shade‐tolerant individuals accounted for >80% of EFN‐bearing plants in forest interior, compared with 2% in forest edge and 29% in fragments. Forest edge and fragment plots had a third fewer EFN‐bearing individuals and species compared with forest interior. This appeared to have important implications for local ant communities as the density of EFN‐bearing trees was the most important variable explaining the species richness of arboreal dominant ants. Our results show that plant loser–winner replacements promoted by forest fragmentation can cascade through higher trophic levels, with implications for forest dynamics and biodiversity conservation.