边缘效应对山地湿性常绿阔叶林附生植物的影响

作为热带、亚热带地区森林生态系统中重要组成成分之一的附生植物,对环境变化尤为敏感。为了解附生植物对森林生境破碎化的响应,本研究选择哀牢山北段徐家坝山地湿性常绿阔叶林因人为干扰而形成的四处森林边缘为研究对象,分别在距离林缘10、20、40和80m的位置设立样带,采用树干取样法调查各样带内距地面0-2m范围附生植物的物种组成、生物量和附生苔藓植物的生活型特征。结果显示：边缘效应对单位面积附生植物的生物量和附生苔藓植物盖度均具有极显著的影响（P〈0．001）,其中附生苔藓比附生蕨类对边缘效应更为敏感。边缘效应对附生苔藓植物的作用强度在各生活型之间存在着差异,其中对丛集型（P=0．014）和交织型（P=0．030）的附生苔藓植物的影响最显著。综合附生植物在各样带的分布特征,我们认为单位面积上附生植物的生物量和附生苔藓植物的盖度可作为指示森林边缘生境的重要指标。黄牛毛藓（Ditrichum pallidum）、角状刺枝藓（Wijkia hornschuchi）和格氏剪叶苔（Herbertus giraldianus）的分布具有指示林缘生境的意义,而尖叶羽藓（Thuidium philibertii）、大羽藓（zcymbifolium）、多疣麻羽藓（Claopodium pellucinerve）、波叶金枝藓（Pseudotrismegistia undulata）和扭叶藓（Trachypus bicolor）的分布局限于林内,具有一定的保护价值。     

云南哀牢山山地湿性常绿阔叶林附生植物的多样性和分布

附生植物对山地森林生态系统的物种多样性形成及其维持机制、生态系统的水分和养分循环等有重要作用。作者调查分析了云南哀牢山原生山地湿性常绿阔叶林 80株不同种类、不同径级乔木上附生植物种类、数量及空间分布特征,结果表明该区森林附生植物种类较为丰富。共收集到附生植物 69种,分属 33科 49属,其中维管束植物32种,苔藓植物 37种。附生维管束植物的Shannon Wiener指数和Simpson指数分别为 2. 93和 0. 91,附生苔藓植物分别为 3. 31和 0. 95。附生维管束植物中蕨类较为丰富,以棕鳞瓦韦 (Lepisorusscolopendrium)、拟书带蕨 (Vittariaflexuosoides)、柔毛水龙骨(Polypodiodesamoenavar. pilosa)等为主;附生种子植物以黄杨叶芒毛苣苔 (Aeschynanthusbuxifolius)、长叶粗筒苣苔(Briggsialongifolia)、白花树萝卜 (Agapetesmannii)等为主。该地区全年气候潮湿、温凉,使得附生苔藓植物非常丰富,主要优势种类包括东亚鞭苔 (Bazzaniapraerupta)、小叶鞭苔 (B. ovistipula)、齿边广萼苔(Chandonanthushirtellus)、树平藓 (Homaliodendronflabellatum)、刺果藓 (Symphyodonperrottetii)、青毛藓 (Dicran odontiumdenudatum)、小蔓藓(Meteoriellasoluta)、尖喙藓(Kindbergiapraelonga)等。从空间分布特点上看,     

Large-scale diversity patterns of vascular epiphytes in Neotropical montane rain forests

Aim Epiphytes contribute up to 30% to the number of vascular plant species in certain global biodiversity hotspots, e.g. the Ecuadorian Andes. However, their large scale diversity patterns are still discussed on the base of results from a few, local epiphyte inventories. Consequently, explanatory models on epiphyte diversity concentrate on the impact of local climate on small scale epiphyte species richness. Our aim was to analyse large scale elevational patterns of epiphyte diversity integrating data from different geographic scales. Location Tropical America, with special emphasis on the Ecuadorian Andes. Methods Our study is based on two data sources. First, we analysed the elevational patterns of epiphyte diversity based on the Catalogue of the Vascular Plants of Ecuador and the Libro Rojo de las Plantas Endèmicas del Ecuador. Secondly, the floristic turnover between the epiphyte inventories of seven montane and four lowland study sites in the Neotropics was analysed. Results The floristic turnover between Neotropical montane epiphyte floras is higher than the one between lowland epiphyte floras. Montane study sites located only a few kilometres apart from each other show considerable differences in their epiphyte species inventories. Irrespectively of their similar dispersal mode, the floristic turnover is much higher for orchids than for Pteridophyta. The Orchidaceae are the species richest group in all of the examined 11 Neotropical epiphyte floras. At the larger scale of the Ecuadorian Flora, c. 50% of the species in the elevational zone with maximum epiphyte diversity (between 1000 and 1500 m) are orchids. Elevational patterns of epiphyte diversity strongly reflect patterns of Orchidaceae. Main conclusions Our results support the observation of a ‘mid‐elevation bulge’ of epiphyte diversity by Gentry and Dodson. It has been frequently shown that the high humidity in mid‐elevations is suitable to maintan a high epiphyte species richness. Our findings show that in addition, large scale epiphyte diversity in montane rain forest is increased by the high floristic turnover at local and regional scale. Based on the importance of Orchidaceae for epiphyte diversity, we discuss that speciation processes corresponding to the highly diverse environment are a driving force for endemism, floristic heterogeneity and consequently for large scale epiphyte species richness in montane forests.     

Edge effects on palm diversity in rain forest fragments in western Ecuador

At the edges of tropical rain forest fragments, altered abiotic and biotic conditions influence the structure and dynamics of plant communities. In Neotropical rain forests, palms (Arecaceae) are important floristic and ecological elements. Palms’ responses to edge effects appear to be idiosyncratic and to depend on the level of disturbance at edges. This paper explores how variation in forest structure at the edges of two old-growth forest fragments in a tropical rain forest in western Ecuador affects palms of different species, life-forms, and size classes. We investigate (1) how edge effects influence the relative proportion of palm adults and juveniles, (2) how distance from the forest edge affects palm density and species richness, (3) how altered forest structure along edges affects palm density. We found that at edges (1) palm communities had a lower proportion of adults relative to juvenile individuals compared to continuous forests, (2) the density of two species of palms and the overall species richness of the palm community tended to decrease toward the edges within forest fragments, and, (3) altered forest structure decreased the density of adult palms. Hence, edge effects on palms were controlled by the degree of modification of the forest structure, and by species responses to edge-related disturbance.     

Composition and structure of a humid montane forest on the Pasochoa volcano, Ecuador

In a one-hectare plot in humid montane forest on Volcán Pasochoa (3,260–3,300 m), one of the last remnants of the inter-Andean forest between the two Ecuadorean cordilleras, there were 1,058 trees ≥ 5 cm dbh in 32 different species with a total basal area of 25.7 m². The most common species were Miconia theaezans, Piper andreanum , and Miconia pustulata with 32%, 14% and 8% of the individuals, respectively. Three species ( Hesperomeles lanuginosa, Boehmeria fallax and Lamiaceae sp.) were represented by only a single individual. Melastomataceae was the most important family with six species, over 50% of the individual trees, and 68% of the basal area. Other important families were Piperaceae and Asteraceae. The abundance of assumed pioneer species suggests that either the forest has been altered by humans in the past, or that their dominance is a part of the dynamic regeneration of a forest growing on steep slopes with inclinations between 36 and 120% in the plot. The diameter class distribution of Miconia corymbiformis and Axinaea macrophylla shows a light-demanding species behavior. Trees with multiple stems characterize this forest perhaps in order to distribute their weight on such steep slopes.     

中国森林附生维管植物多样性数据集

附生维管植物是热带、亚热带湿性山地森林植物群落中物种最为丰富的类群之一, 在维系森林生物多样性及生态系统功能与服务中发挥着重要作用, 然而附生维管植物调查相对困难, 在多样性调查和统计中往往被忽视, 迄今为止我国尚缺乏全国范围的森林附生维管植物名录。本项研究基于已公开发布的数据库, 搜集并整理了1982-2022年间的关于中国森林附生维管植物研究的文献书籍。首先, 提取文献资料中的有效信息, 依据物种2000中国节点的数据进行标准化校正, 整理出中国森林附生维管植物共计49科246属1,739种, 然后据此编写了相对准确、完整的中国森林附生维管植物物种名录。本名录作为我国第一个全国性森林附生维管植物名录, 可为森林生物多样性保护工作提供重要的数据支持, 并能为深入研究附生维管植物的进化生物学、生物地理学及宏观生态学等领域提供重要的基础信息。     

Unique elevational diversity patterns of geometrid moths in an Andean montane rainforest

Alpha‐diversity of geometrid moths was investigated along an elevational gradient in a tropical montane rainforest in southern Ecuador. Diversity was measured using 1) species number, 2) extrapolated species number (Chao 1 estimator), 3) rarefied species number, and 4) Fisher's alpha. When applied to the empirical data set, 1 and 2 strongly depended on the sample size, whereas 3 and 4 were suitable and reliable measures of local diversity. At single sites, up to 292 species were observed, and extrapolation estimates range from 244 to 445 species. Values for Fisher's alpha are among the highest ever measured for this moth family, and range from 69 to 131 per site. In contrast to theoretical assumptions and empirical studies in other regions of the world, the diversity of geometrid moths remained consistently high along the entire gradient studied. Diversity measures correlated with neither altitude nor ambient temperature. The large subfamily Ennominae has previously been assumed to be a group that occurs mainly at low and medium elevations. However, no decline in diversity was found in the study area. The diversity of the other large subfamily, Larentiinae, even increased from the lowest elevations and was highest at elevations above 1800 m. The roles of a decreasing diversity of potential host‐plants, decreasing structural complexity of the vegetation, increasingly unfavourable climatic conditions and possible physiological adaptations in determining herbivore species richness are discussed. A relatively low predation pressure might be an advantage of high‐altitude habitats. The physiognomy of the Andes (folded mountains, large areas at high altitudes) might also have allowed speciation events and the development of a species‐rich high‐altitude fauna. There is evidence that the species‐richness of other groups of herbivorous insects in the same area declines as altitude increases. This emphasises difficulties that are associated with biodiversity indicator groups, and calls for caution when making generalisations from case studies.     

Patterns in the diversity and distribution of epiphytes and vines in a New Zealand forest

Abstract Plants that rely on other plants for support (i.e. epiphytes and vines) are common in many forest ecosystems. However, they are poorly understood relative to terrestrial plants, especially in the Southern Hemisphere. To help bridge this gap, we evaluated the diversity and distribution of vascular epiphytes and vines on seven common tree species in a conifer‐broadleaf forest on New Zealand's North Island. Ground‐based surveys of 274 host trees were used to test whether epiphyte and vine diversity increased with tree diameter, and whether diversity‐diameter relationships differed among host tree species. Occurrence patterns of individual epiphyte and vine species were also assessed. We first evaluated the accuracy of ground‐based inventories by comparing surveys of trees made from the ground to those made from a canopy walkway. On average, 1 in 10 species of epiphytes and vines were unseen from the ground. However, sampling accuracy did not differ among the three host tree species growing along the walkway, suggesting unbiased comparisons could be made between hosts. Results from ground‐based surveys showed that species diversity of epiphytes and vines increased with host tree diameter. However, epiphytes showed stronger diversity‐diameter relationships than vines. Epiphyte diversity increased markedly in four host species and less strongly in the remaining three host species. Conversely, vines showed weak diversity‐diameter relationships in all host species. Occurrence patterns of individual species helped to explain diversity‐diameter relationships. All common epiphyte species occurred more frequently on large trees, regardless of host species, but occurrence patterns in most vine species were unrelated to tree size. Rather, the vines often showed strong host ‘preferences’. Overall results illustrate a rich diversity of distributional patterns in New Zealand's epiphytes and vines, and suggest that a similarly diverse set of ecological and evolutionary processes are responsible for them.     

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.     

Topographic and spatial controls of palm species distributions in a montane rain forest, southern Ecuador

The northern Andes harbour a flora that is as species-rich or even richer than the 18-times larger lowland Amazon basin. Gaining an understanding of how the high species richness of the Andean region is generated and maintained is therefore of particular interest. Environmental sorting due to elevational gradients in climate has been emphasized as a driver of vegetation distribution and plant community assembly in tropical mountain areas such as the Andes for two centuries, while alternative mechanisms have been little studied. Here, we investigated the importance of topography and spatial location as factors controlling species distributions in a palm community in a montane rain forest landscape in the Andes of southern Ecuador (1900–2150 m above sea level). Eleven species were present: Aiphanes verrucosa, Ceroxylon parvifrons, Chamaedorea pinnatifrons, Dictyocaryum lamarckianum, Euterpe precatoria, Geonoma densa, Geonoma orbignyana, Geonoma paradoxa, Prestoea acuminata and Wettinia aequatorialis. To study their spatial distribution, forty 250 m² (5 × 50 m²) plots were laid out perpendicular to four paths that were categorized into three areas and two topographic units (ridges and gullies). Mantel tests and indicator species analysis showed that both topography and spatial location imposed strong controls on palm species distributions at the study site. Our results suggest that species distributions in the studied montane forest landscape were partly determined by the species’ habitat requirements, but also by unknown spatial effects. Although a number of possible explanations exist for the latter, such as unmeasured environmental variables and historical disturbance events, we believe dispersal limitation is likely to be involved. Furthermore, although the gully- or ridge-association of some species corresponded to their general elevational ranges in southern Ecuador, this was not the case for other species. Based on such considerations, we conclude that elevational climatic gradients are likely to only form part of the explanation for the topographic effects on palm species distributions at the study site. Other factors must also be involved, notably wind-exposure and hydrology, as discussed for lowland palm communities. Our results show that to understand plant community assembly in the tropical montane forests of the Andes it is too simple to focus just on environmental sorting by elevational climatic gradients.     

Change in water quality during the passage through a tropical montane rain forest in Ecuador

We studied five 20-m transects onthe lower slope under tropical lower montanerain forest at 1900–2200 m above sea level. We collectedsamples of soil and of weekly rainfall,throughfall, litter leachate, and stream waterbetween 14 March 1998 and 30 April 1999 anddetermined the concentrations of Al, totalorganic C (TOC), Ca, Cl^–, Cu, K, Mg, Mn,NH₄ ⁺-N, NO₃ ^–-N, total N (TN), Na, P, S, and Zn. The soils were shallowInceptisols; pH ranged 4.4–6.3 in the Ohorizons and 3.9–5.3 in the A horizons, totalCa (6.3–19.3 mg kg^–1) and Mgconcentrations (1.4–5.4) in the O horizon weresignificantly different between the transects.Annual rainfall was 2193 mm; throughfall variedbetween 43 and 91% of rainfall, cloud waterinputs were 3.3 mm a^–1 except forone transect (203). The volume-weighted mean pHwas 5.3 in rainfall and 6.1–6.7 in throughfall.The median of the pH of litter leachate andstream water was 4.8–6.8 and 6.8, respectively.The concentrations of Ca and Mg in litterleachate and throughfall correlatedsignificantly with those in the soil (r =0.76–0.95). Element concentrations inthroughfall were larger than in rainfallbecause of leaching from the leaves (Al, TOC,Ca, K, Mg), particulate dry deposition (TOC,Cu, Cl^–, NH₄ ⁺-N), and gaseousdry deposition (NO₃ ^–-N, total N, S).Net throughfall (= throughfall-rainfalldeposition) was positive for most elementsexcept for Mn, Na, and Zn. High-flow eventswere associated with elevated Al, TOC, Cu, Mn,and Zn concentrations.     

Ficus lacunata (Moraceae), a new species from pluvial montane forest of northwest Ecuador

Ficus lacunata Kvitvik, a new species of subgen.Pharmacosycea sect.Pharmacosycea collected in the provinces of Carchi, Imbabura, and Pichincha in Ecuador, shows affinities to bothFicus macbridei Standl. andFicus tonduzii Standl. but differs distinctly in leaf and syconium characters.     

Faunal composition of geometrid moths changes with altitude in an Andean montane rain forest

Aim The objective of this study was to describe and interpret the changes in faunal composition in the moth family Geometridae (Lepidoptera) along a small‐scale elevational gradient in a tropical montane rain forest. This gradient was compared with a large‐scale latitudinal gradient in Europe. Location Investigations were carried out in the province Zamora‐Chinchipe in southern Ecuador along a gradient ranging from 1040 to 2677 m above sea level at twenty‐two sites. Methods Moths were sampled with light‐traps in three field periods in 1999 and 2000 and subsequently sorted and determined to species or morphospecies. Results We analysed 13,938 specimens representing 1010 species of geometrid moths. The proportional contribution of subtaxa to the local geometrid fauna changes along the elevational gradient at all systematic levels considered. While proportions of species of the subfamilies Ennominae, Sterrhinae and Geometrinae significantly decrease, the proportion of Larentiinae increases with increasing altitude. Changes also occur within the subfamilies Ennominae and Larentiinae. The host–plant specialist ennomine tribes Cassymini, Macariini and Palyadini completely vanish, and the proportion of the tribe Boarmiini decreases at high altitudes. In contrast, the remaining tribes (mostly comprising polyphagous species) either do not show proportional changes (Azelinini, Nacophorini, Nephodiini, Ourapterygini) or even increase (Caberini, ‘Cratoptera group’). Within Larentiinae, the species proportion of the genus Eois decreases, whereas concomitantly the proportion of Eupithecia increases. There is a remarkable similarity between the altitudinal patterns in Ecuador and those found along the latitudinal gradient in Europe. Main conclusions Species of the subfamily Larentiinae seem to be particularly well‐adapted to harsh environmental conditions, towards both high altitudes and latitudes. They might disproportionately profit from lower predation at higher altitudes. Many changes in the faunal composition can be explained by expected host–plant requirements of the species involved. Our results show that diversity estimates based on taxon ratios which are assumed to be constant must be regarded with caution because such ratios can change rapidly along environmental gradients.     

Habitat loss effects on spatial distribution of non-vascular epiphytes in a Brazilian Atlantic forest

The vertical distribution of the richness, abundance, and composition of epiphytic bryophytes was studied in a matrix of fragmented habitats in the Brazilian Atlantic rainforest of the Murici Ecological Station (9°11′05″–9°16′48″ S, 35°45′20″–35°55′12″ W), northeastern Brazil. The aim was to compare the horizontal (between sites) and vertical (between phorophyte heights) turnover to test a hypothesis based on niche width vulnerability. There was a highly significant decreasing of richness accompanying the loss of habitat, and the most conserved fragment housed a total richness more than 10 times higher than the less conserved fragment. Epiphytes failed to colonize lower trunks (2.1–10 m) and higher zones in most of the non-conserved fragments; they were restricted to the base (0–2 m) and displayed a clear altered floristic composition. The species with restricted ecological amplitudes such as sun and shade tolerant taxa were more negatively affected by habitat loss than generalists. Although the mean richness of generalists decreased in non conserved fragments, the proportional contribution of this guild increased, proving that these taxa are the ones which persist in disturbed sites. The forest fragments capable of harboring rich epiphyte flora in the area studied are over 300 ha in size, which is far from being a common size among Brazilian Atlantic rainforest fragments. Hence, our results highlight the need of conserving the few large remnants in this ecosystem.     

Biomass and water storage dynamics of epiphytes in old-growth and secondary montane cloud forest stands in Costa Rica

The way competition structures plant communities has been investigated intensely over many decades. Dominance structures due to competitive hierarchies, with consequences for species richness, have not received as much experimental attention, since their manipulation is a large logistic undertaking. Here the data from a model system based on bryophytes are presented to investigate competition structure in a three-species system. Grown in monocultures, pairwise and three-species mixtures under no and high nitrogen supply, the three moss species responded strongly to treatment conditions. One of them suffered from nitrogen fertilisation and hence performed better in mixtures, where the dominant species provided physical shelter from apparently toxic nitrogen spray. Accordingly, no linear competitive hierarchy emerged and qualitative transitivity remains restricted to the unfertilised treatments. Faciliation also affected other properties of the competition structure. The reciprocity of competition effects could not be observed. Moreover, the performances in three-species mixtures were not well predictable from the knowledge of monocultures and pairwise mixtures because competitive effects were not additive. This had implications for community stability at equilibrium: all two-species systems were stable, both fertilised and unfertilised, while the three-species system was only stable when fertilised. This stability under fertilisation has probably to do with the facilitative effect of the two dominant species on the third. In this experiment, little support for commonly held ideas was found about the way competition in plant communities is structured. On the other hand, this study shows that moss communities are ideal model systems to test predictions of theoretical models concerning properties and consequences of competition in plant communities.     

Relationships between frequency of mixed-species flocks, weather and insect activity in a montane cloud forest in Ecuador

The frequency of mixed-species flocks of birds, weather and insect activity were studied in a high-altitude cloud forest in Ecuador. It is generally accepted that participation in mixed-species flocks improves foraging efficiency. If this is true, more flock activity may be expected when food is less available, which may happen during long-lasting periods of rain and otherwise adverse weather conditions. The total number and mean size of flying insects decreased as rainfall increased. The number of flocks observed increased with decreasing number and biomass of insects. Relatively more flocks were seen during rain than during dry weather. No flocks stopped foraging during rain. The flock activity pattern appeared to be the opposite of that found in humid lowlands, probably because of different weather regimes in the two zones. In the lowlands, heavy rain is typically of short duration. In high-altitude cloud forest, the rainfall is often less intense but persists for prolonged periods. Hence, from an energy point of view, cloud forest birds cannot afford to stop foraging during adverse weather conditions when insect availability is low. The results suggest that some mixed feeding parties have evolved in response to low tropical insect availability, necessitating long feeding excursions outside the territory.     

Diversity and abundance of vascular epiphytes: a comparison of secondary vegetation and primary montane rain forest in the Venezuelan Andes

Species diversity of vascular epiphyte plant communities was studied in La Carbonera, a montane rain forest dominated by Podocarpaceae in the Venezuelan Andes. We compared the epiphyte communities of the primary, disturbed, and secondary forest areas of La Carbonera in order to augment the scarce knowledge on the effects of anthropogenic disturbance on these important elements of tropical vegetation. Diversity of vascular epiphytes (191 species in the whole forest area) was low in the disturbed and secondary areas (81 spp.) compared to adjacent primary forest (178 spp.). Four types of disturbed forest and secondary vegetation supported different numbers of epiphyte species, showing a decline with increasing degrees of disturbance (65 spp. along a road transect, 42 spp. on relict trees in disturbed forest, 13 spp. in a tree plantation and 7 spp. in a former clearing, both secondary vegetation units). Epiphytic species composition in primary and disturbed or secondary forest areas differed markedly: disturbed habitats harboured fewer fern and orchid species but more bromeliad species than the primary forest. Probably the families occurring only in primary forest sites of our study may be useful as bioindicators to determine the degree of disturbance in other habitats of mountain rain forests as well. Epiphyte abundance was also lower in disturbed habitats: a remnant emergent tree supported only about half as many epiphyte individuals as a member of the same species of similar size in the primary forest. The decrease in species numbers and abundance as well as the differences in species composition are mainly due to the less diverse phorophyte structure and less differentiated microclimate in the disturbed and secondary vegetation compared to the primary forest.     

Interactions between epiphytes during canopy soil formation: an experiment in a lower montane cloud forest of southeast Mexico

• In several montane forests around the world, epiphytes coexist in mats, sharing the rhizosphere and forming histosol-type soils rich in nutrients. The role of these epiphytes in the formation of canopy soil and the fitness costs that epiphytes face when cohabiting in these mats are unknown.
• In a lower montane cloud forest in central Veracruz, Mexico, a 2-year factorial experiment was carried out with the presence/absence of ramets of Phlebodium areolatum (Polypodiaceae), Tillandsia kirchhoffiana, T. multicaulis and T. punctulata (Bromeliaceae). We examined (i) which epiphyte species contribute to the formation of canopy soil, (ii) the role of epiphyte composition in the soil nutrient composition, and (iii) the fitness costs faced by epiphytes when cohabiting.
• Canopy soil formation highest when P. areolatum is present. Soil nutrient content does not change with epiphyte composition, is influenced by the microbiota, and P content decreases with the presence of epiphytes. The fitness costs show that the species compete, decreasing their survival and growth, but the competitive capacity differs between the species.
• We conclude that P. areolatum is an ecosystem engineer that promotes the creation of canopy soil but is a poor competitor. The results coincide with the model of succession by facilitation. Canopy soil is a slow-created component whose nutrient content does not depend on the epiphytic flora. In epiphyte mats, the dominant interactions are competitive, but there is also facilitation.

     

Stable isotope signatures reflect dietary diversity in European forest moths

Background

Information on larval diet of many holometabolous insects remains incomplete. Carbon (C) and nitrogen (N) stable isotope analysis in adult wing tissue can provide an efficient tool to infer such trophic relationships. The present study examines whether moth feeding guild affiliations taken from literature are reflected in isotopic signatures.

Results

Non-metric multidimensional scaling and permutational analysis of variance indicate that centroids of dietary groups differ significantly. In particular, species whose larvae feed on mosses or aquatic plants deviated from those that consumed vascular land plants. Moth δ¹⁵N signatures spanned a broader range, and were less dependent on species identity than δ¹³C values. Comparison between moth samples and ostensible food sources revealed heterogeneity in the lichenivorous guild, indicating only Lithosia quadra as an obligate lichen feeder. Among root-feeding Agrotis segetum, some specimens appear to have developed on crop plants in forest-adjacent farm land. Reed-feeding stem-borers may partially rely on intermediary trophic levels such as fungal or bacterial growth.

Conclusion

Diagnostic partitioning of moth dietary guilds based on isotopic signatures alone could not be achieved, but hypotheses on trophic relationships based on often vague literature records could be assessed with high resolution. Hence, the approach is well suited for basic categorization of moths where diet is unknown or notoriously difficult to observe (i.e. Microlepidoptera, lichen-feeders).