On the occurrence of a velamen radicum in Cyperaceae and Velloziaceae

Roots of tree-like Cyperaceae ( Afrotrilepis pilosa, Bulbostylis leucostachya, Coleo-chloa setifera, Microdracoides squamosus ) and Velloziaceae ( Vellozia variegata, Xe-rophyta pinifolia ) were examined by light and scanning electron microscopy. For the first time a velamen is reported for Bromeliiflorae and Commeliniflorae. All species studied possess a velamen radicum that is either one-layered ( Microdracoides, Bulbostylis, Coleochloa ) or multi-layered ( Afrotrilepis, Vellozia, Xerophyta ). Anticlinal walls of the velamen cells of Microdracoides show perforations similar to those found in orchids. A multiple exodermis delimits the velamen towards the cortex. As in epiphytic Orchidaceae, a velamen may be of considerable adaptive value for arborescent Cyperaceae and Velloziaceae. These mainly occur in edaphically and climatologically extreme habitats (e.g. tropical inselbergs) where rapid water uptake is of crucial importance.     

Morphological analysis, phylogenies and classification in Velloziaceae

A morphological (non-molecular) cladistic analysis of the Velloziaceae is presented. The terminal taxa are 47 species of Velloziaceae plus four taxa as outgroups: Acanthochlamys bracteata (Acanthochlamydaceae), Encholirium scrutor (Bromeliaceae), Thoracocarpus bissectus (Cyclanthaceae) and Pandanus racemosus (Pandanaceae). The species of Velloziaceae sampled represent a significant proportion of the morphological diversity of the family, including all recognized genera and sections. The analysis revealed two major groups within Velloziaceae, supported mainly by stomata, vascular bundles in the pedicel, aquiferous tissues, filaments, anthers, pollen, stigma, seeds, ploidy and chemical characters. Comparison between this and the previous phylogenetic hypotheses for Velloziaceae, together with the two conflicting current classifications, suggests that there is incompatibility concerning the support of current genera and sections. The only three groups supported in all phylogenies are Barbacenioideae sensu Menezes (= Barbacenia sensu Smith & Ayensu), Xerophyta sect. Barbacenioides and Xerophyta sect. Xerophyta sensu Smith & Ayensu.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 157–173.     

Granitic and gneissic outcrops (inselbergs) as centers of diversity for desiccation-tolerant vascular plants

Although desiccation tolerance is common in non-vascular plants, this adaptive trait is very rare in vascular plants. Desiccation-tolerant vascular plants occur particularly on rock outcrops in the tropics and to a lesser extent in temperate zones. They are found from sea level up to 2800 m. The diversity of desiccation-tolerant species as measured by number of species is highest in East Africa, Madagascar and Brazil, where granitic and gneissic outcrops, or inselbergs, are their main habitat. Inselbergs frequently occur as isolated monoliths characterized by extreme environmental conditions (i.e., edaphic dryness, high degrees of insolation). On tropical inselbergs, desiccation-tolerant monocotyledons (i.e., Cyperaceae and Velloziaceae) dominate in mat-like communities which cover even steep slopes. Mat-forming desiccation-tolerant species may attain considerable age (hundreds of years) and size (several m in height, for pseudostemmed species). Both homoiochlorophyllous and poikilochlorophyllous species occur. In their natural habitats, both groups survive dry periods of several months and regain their photosynthetic activity within a few days after rainfall. Other desiccation-tolerant species colonize shallow depressions, crevices and even temporarily water-filled rock pools on inselbergs. Desiccation-tolerant vascular plants occur in 13 families and are best represented within the monocotyledons and ferns. Only a few desiccation-tolerant dicots exist, in the Gesneriaceae, Myrothamnaceae and Scrophulariaceae. In total, about 330 species of vascular desiccation-tolerant plants are known, of which nearly 90% occur on inselbergs. With regard to morphological adaptations, the mat-forming monocotyledons are particularly remarkable due to the possession of roots with a velamen radicum, which is reported here in the genus Borya for the first time.     

The genetic diversity of two brazilian vellozia (velloziaceae) with different patterns of spatial distribution and pollination biology

BACKGROUND AND AIMS: The genetic structure and variability of two species of Vellozia (Velloziaceae) with restricted distribution in high-altitude quartzitic fields in south-eastern Brazil were studied. Vellozia epidendroides is short, grows on pebbly or sandy soil, and is pollinated by bees. Vellozia leptopetala is arborescent, grows on rock outcrops, and is pollinated by bees and hummingbirds. Both are self-incompatible and have a short, massive flowering strategy. The study aimed to associate differences in their genetic diversity and structure with their microhabitat distribution and pollination ecology. METHODS: Leaves from 106 and 139 plants of V. epidendroides and V. leptopetala, respectively, were collected from five patches of each species and prepared for electrophoretic analyses. KEY RESULTS: Five enzyme systems could be reliably scored for both species. Vellozia epidendroides showed 100 % of the loci polymorphic for almost all patches. The average number of alleles per locus ranged between 2.2 and 2.4 among patches. The Wright's fixation index (F) for this species was 0.226. A significant (p) value indicates that there is a reasonable genetic divergence among patches. Vellozia leptopetala presented 47.5 % of polymorphic loci. All levels of P, A, A(p) and of heterozygosities were lower than those of V. epidendroides. Vellozia leptopetala showed high inbreeding within patches. CONCLUSIONS: The relatively high values of genetic diversity indices found for V. epidendroides may be associated with its large and widespread populations. On the other hand, the low values of genetic diversity found for V. leptopetala may be related to physical isolation on outcrops and intensive foraging by territorial hummingbirds, which may hinder gene flow among patches, aggravated by the very restricted seed dispersal characteristic of the genus, that facilitates sibling mating. It is important to stress the need to preserve the specific habitats of these species of Vellozia, in particular those of V. leptopetala that has lower genetic diversity and is restricted to rock outcrop environments.     

A species-poor tropical sedge community: Afrotrilepis pilosa mats on inselbergs in West Africa

The mat-forming poikilohydric sedge Afrotrilepis pilosa (Cyperaceae) occurs as the dominant member of characteristic stands on West African inselbergs. The species composition of this community has been examined in the Ivory Coast along a latitudinal gradient from the savanna to the rainforest region. Inselbergs consisting of Precambrian granites and gneisses, are prominent landscape elements characterized by large areas of exposed rock. Monocotyledonous mats are one of the most conspicuous communities of this ecosystem. Floristically, the mats are poor in higher plant species with a total of only 15 species (mostly therophytes) recorded in 110 relevés. Species diversity is likewise low, indicating extremely stressful environmental conditions. A major factor affecting plant colonization is the pronounced short-term variation in water-availability, even in the more humid regions in the south of the country. Afrotrilepis pilosa is highly competitive under these conditions, and the dense stands leave only little space for other species to become established. Longevity (attaining an age of several hundred years) and the ability, to spread radially to form almost monospecific stands are further characteristics which render this species a superior competitor. In marked contrast with most other tropical vegetation types, Afrotrilepis mats have therefore to be regarded as an example of a naturally occurring, extremely species-poor community, in which competitive displacement and the low degree of disturbance prevent higher diversity.     

Contents of sugars in leaves of drying desiccation tolerant flowering plants, particularly grasses

Sugar complements were analysed in extracts from leaves of desiccation tolerant species in the angiosperm families Cyperaceae, Gesneriaceae, Liliaceae, Poaceae and Velloziaceae. Total sugar content was higher in live air-dry leaves of all desiccation tolerant species (except the grass Eragrostiella nardoides; 22 µmoles/g dw) than in the dead air-dry leaves of the desiccation sensitive grass Sporobolus pyramidalis (36 µmoles/g dw). Sucrose contents rose to high levels (40–98 µmoles/g dw) in live air-dry leaves of all species (except the grass Eragrostiella nardoides in which it rose to only 11 µmoles/g dw) to become the predominant sugar. Glucose and/or fructose contents frequently were lower after leaf drying but usually these were the sugars of next highest contents in live air-dry leaves. Contents of raffinose (that has been postulated to reduce sucrose crystallization) rose to c. 10% of sucrose contents in air-dry leaves of most desiccation tolerant species (but only c. 4% in Tripogon jacquemontii) compared with c. 2% of sucrose contents in the sensitive grass S. pyramidalis. Trehalose (a rare sugar in seed-plants) was present in all but one desiccation tolerant species (Xerophyta villosa) but only in minor amounts. The results are consistent with the views that sugars play a protective role during drying of desiccation tolerant plants in general but that other factors are also involved indesiccation tolerance, that in desiccation tolerant angiospermae sucrose is generally the predominant protective sugar and that raffinose and trehalose may supplement the role of sucrose.     

Seasonal Dynamics of Plant Diversity on lnselbergs in the Ivory Coast (West Africa)

Inselbergs are isolated monolithic outcrops which are characterized by large areas of exposed crystalline rock. Due to harsh edaphic and microclimatic conditions, inselbergs are completely differentiated from their surroundings. Consequently they host a very distinct vegetation which is being investigated on a global scale over a six year period. The seasonal dynamics of Selected plant communities (Afrotrilepis pilosa mat, shallow depression, ephemeral flush vegetation) on granitic inselbergs in the Comoe National Park (NE Ivory Coast) were studied during the rainy period from May to November 1991 by recording all vascular plant species at 12 intervals. For the habitats investigated, the seasonal vegetation dynamics were related to the rainfall pattern. Maximum values both in species diversity and richness were attained in the first third of the rainy period. Drought in August and September caused a decline in species number and diversity in the shallow depression and ephemeral flush vegetation, resulting in mortality of more than 20% of the species. The individual communities studied differed considerably in species diversity and richness. We conclude that ephemeral flush and shallow depression communities are more species rich than the mat community which is dominated by the highly competitive and specialized K-strategist Afrotrilepis pilosa (a poikilohydric Cyperaceae) due to stochastic climatic perturbations which allow the maintenance of species rich non-equilibrium assemblages with r-strategists as major components.     

Effects of altitude and climate in determining elevational plant species richness patterns: A case study from Los Tuxtlas,Mexico

Altitudinal changes of composition and richness of montane plant assemblages are complex, depending on the taxonomic group and gradient conditions, with different factors involved that are directly altitude-dependent (e.g., temperatures, air pressure) and altitude-independent (e.g., precipitation, cloud cover, area). In order to assess the relative impacts of temperature, precipitation, air humidity, and area of altitudinal belts on plant diversity, we analyzed diversity patterns of five species-rich groups, mostly herbaceous plants, in 74 forest plots along three climatically contrasting elevational transects from humid tropical lowland vegetation up to cloud forests at Los Tuxtlas, Mexico. We recorded 278 plant species, with ferns being the most species-rich group followed by orchids, bromeliads, aroids, and piperoids. The most striking results were the contrasting patterns and model results for terrestrial and epiphytic taxa. Whereas the richness of all terrestrial species taken together did not change significantly with elevation, vascular epiphytes showed increasing species numbers with altitude. However, a number of individual terrestrial taxa showed also significant elevation-related changes: aroids showed a marked decline with hight, orchids and piperoids increased, and ferns displayed a hump-shaped pattern with highest richness in mid-altitudes. Among the epiphytes, aroids declined while most other groups increased with altitude. This distinction is relevant for projections of responses of plant communities to climate change, which will lead to increased temperatures and to changing precipitation and cloud condensation regimes and thus will likely affect terrestrial and epiphytic species in different ways.     

On Arborescence in Gahnia clarkei and Gahnia sieberiana

Specimens of Gahnia sieberiana from Brisbane, Queensland, andof Gahnia clarkei from near Orbost, Victoria, were collectedand examined both morphologically and anatomically. The speciesgrow in wet areas and are of interest because they representthe largest arborescent species known in the Cyperaceae. Stemdiameters up to 120 mm and stems up to 10 m long have been observed.Such long stems tend to be supported by nearby vegetation. Althoughfresh stems are tough and woody, they are brittle. Branchingof the stems is sympodial, and numerous branches are producedby plants growing in exposed habitats. There is less branchingin plants from shaded habitats. Basal shoots may also occur.Adventitious roots develop basally on most plants, but withG. sieberiana, some adventitious roots form near the shoot apexand grow in and around leaf bases. Anatomical features of interestare an endodermoid layer composed of sclereids with elongate,undulated, outer tangential walls that are lignified and suberized,short vessel elements with horizontal to oblique simple perforationplates, and relatively short sclereids surrounding vessel elementsin the vascular bundles. Some vascular bundles are bipolar.The presence of short vessel elements here is in marked contrastto the longer tracheary elements in other arborescent monocotyledons. Arborescence, stem anatomy, Cyperaceae, Gahnia, saw sedge, Monocotyledon, bipolar bundles, morphology, endodermoid layer     

The geographic range size and vulnerability to extinction of angiosperm epiphytes in the Atlantic Forest of Brazil

Aim

Angiosperm epiphytes have long been reported to have larger geographic ranges than terrestrial species, despite evidence of their outstanding diversity and endemism. This apparent contradiction calls for further investigation of epiphytes' poorly understood range size patterns. Here, we address the question of whether epiphytes have larger geographic ranges and different vulnerability to extinction than terrestrial species.

Location

The Atlantic Forest of Brazil, a global centre of tropical epiphyte diversity with relatively well-known flora, where we can estimate the geographic ranges of a large number of species with reasonable confidence.

Time period

Occurrence records from the 17th century to the year 2021.

Major taxa studied

Flowering plants (angiosperms).

Methods

We downloaded, processed and cleaned all occurrence records for the angiosperm species native to the Atlantic Forest of Brazil available in the speciesLink network and the Global Biodiversity Information Facility. We estimated the extent of occurrence and area of occupancy of 12,679 native flowering plants, including 1251 epiphytic species. We compared the geographic ranges of epiphytes and other life forms at broad (e.g. Angiosperms, Monocots) and more restricted taxonomic scales (e.g. individual families), assuming species are independent entities and also when accounting for species phylogenetic dependence.

Results

We found that epiphytes have among the smallest geographic ranges of flowering plants. We found no consistent evidence that epiphytism leads to differences in geographic ranges between close relatives. However, both epiphytes and non-epiphytes in epiphyte-rich lineages have small ranges and likely a high vulnerability to extinction.

Main Conclusions

Our findings contrast with the long-held hypothesis that epiphytes have larger geographic ranges than terrestrial species. Epiphytes and their close relatives share many diversification mechanisms and ecological adaptations (‘epiphyte-like traits’), which probably explain why both sets of species have small range sizes and high vulnerability to extinction.     

Impact of floral traits on the reproductive success of epiphytic and terrestrial tropical orchids

We investigated the relationship between habit, population size, floral traits and natural fruit set levels of 23 tropical orchid species of south-east Bangladesh. We showed that epiphytic orchids had lower fruit set levels than terrestrial species and that habit explained much of the variation in floral traits among the orchids. We compared our results with data from 76 other species occurring in the study area and hypothesize that a suite of floral and population characteristics present in tropical orchids combine in epiphytes to reduce their reproductive success. Characteristics which, in addition to their habit, are associated with low reproductive success are small population size, small inflorescences, non-sectile pollinia and self-incompatibility. Several of these characteristics were phylogenetically conserved and we predict that epiphytes might therefore generally have lower fruit set levels than recorded in terrestrial species. Nectar rewards are uncommon in tropical orchids and nectarless species have displays of larger flowers, which may represent an adaptation to increase pollinator attraction, although other rewards such as oils, waxes and pseudo pollen may replace nectar. We suggest that, like many temperate orchids, a high proportion of tropical orchids may lack floral rewards and be pollinated by deceit.     

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,     

Composition and ecology of vascular epiphyte communities along an altitudinal gradient in central Veracruz,Mexico

Abstract. Vascular epiphytes were studied in forests at altitudes from 720 to 2370 m on the Atlantic slope of central Veracruz, Mexico. The biomass of all trees of each species > 10 cm diameter at breast height within plots between 625 and 1500 m² was estimated. The number of species per plot ranged between 22 and 53, and biomass between 9 and 249 g dry weight/m². The highest values, both of species and biomass, were found at an intermediate altitude (1430 m). Habitat diversity may contribute to epiphyte diversity in humid forests, but the importance of this effect could not be distinguished from the influence of climate. A remarkably high number of bromeliads and orchids grew in relatively dry forests at low altitudes. In wet upper montane forests, bromeliads were replaced by ferns, while orchids were numerous at all sites, except for a pine forest. The number of epiphytic species and their biomass on a tree of a given site were closely related to tree size. According to Canonical Correspondence Analysis, the factor determining the composition of the epiphytic vegetation of a tree was altitude and to some extent tree size, whereas tree species had practically no influence. The only trees which had an evidently negative effect on epiphytes were pines, which were particularly hostile to orchids and to a lesser degree to ferns, and Bursera simaruba, which generally had few epiphytes due to its smooth and defoliating bark.     

Diversity,distribution and host-species associations of epiphytic orchids in Nepal

Associations between epiphytes and their hosts are among the main factors affecting the biodiversity and distribution of epiphytes. While several previous studies explored the association between epiphyte diversity and host characteristics, very little is known about the generality of such associations at larger spatial scales. We aim to explore the associations between diversity and distribution of epiphytic orchids and host characteristics in different localities in Nepal. Epiphytic orchids and their hosts were recorded along the transects in total of 23,539 host individuals. To describe the diversity of orchids in the different localities, a rarefaction function was used. Univariate and multivariate analyses were carried out to explore the associations with locality, host characteristics, and their interactions with locality. In total, we recorded 141 species of orchids growing on 192 host species. The five localities significantly differed in orchid diversity and abundance. The number of orchid individuals per host species significantly increased with increasing number of host individuals. Species richness, abundances, occupancy of orchid species on host species and composition of orchids varied across the localities. Species richness and abundance was significantly higher on hosts in the higher strata and differed between families of host species. Abundance was higher on evergreen hosts. Composition of orchid communities are also associated with host characteristics, such as habit (shrub/tree/climber), bark texture, nature (deciduous/evergreen) and the plant families of host species. This study revealed a high diversity of epiphytic orchids in the localities studied and strong associations between the orchids and their hosts. Future studies looking at the relationships between epiphyte communities and host characteristics need to identify relationships at a wider scale in order to determine whether they are really general rather than site-specific.     

西双版纳热带森林附生维管植物的物种多样性与区系特征

附生植物是山地森林生态系统中重要的结构性成分。因受林冠调查技术限制, 人们对林冠附生植物知之甚少。本文在前人有关西双版纳植物区系研究的基础上, 结合野外调查和标本资料, 对该地区附生植物的物种组成与分布进行了整理。结果表明, 西双版纳热带森林附生维管植物共有29科134属486种, 约占全部维管植物的11%。附生兰科是最丰富的类群(69属293种), 其中以石斛属(Dendrobium) (49种)和石豆兰属(Bulbophyllum) (48种)物种数最多。蕨类是仅次于兰科的附生类群(13科38属97种), 其中水龙骨科(51种)占附生蕨类总数的50%以上。基于生活史和养分来源的划分标准, 该地区48%的附生物种属于兼性附生, 其次是以兰科为主的专性附生(46%), 半附生仅占6%。从区系上看, 西双版纳附生植物属的分布具有明显的热带亚洲性质。附生植物主要分布于资源受限的林冠生境, 对环境变化极为敏感, 在人为干扰日益加剧的背景下, 这类植物正面临严重威胁。因此, 需要加强对西双版纳林冠亚系统的保护。     

The influence of gravity and wind on land plant evolution

Aspects of the engineering theory treating the elastic stability of vertical stems and cantilevered leaves supporting their own weight and additional wind-induced forces (drag) are reviewed in light of biomechanical studies of living and fossil terrestrial plant species. The maximum height to which arborescent species can grow before their stems elastically buckle under their own weight is estimated by means of the Euler-Greenhill formula which states that the critical buckling height scales as the 1/3 power of plant tissue-stiffness normalized with respect to tissue bulk density and as the 2/3 power of stem diameter. Data drawn from living plants indicate that progressively taller plant species employ stiffer and lighter-weight plant tissues as the principal stiffening agent in their vertical stems. The elastic stability of plants subjected to high lateral wind-loadings is governed by the drag torque (the product of the drag force and the height above ground at which this force is applied), which cannot exceed the gravitational bending moment (the product of the weight of aerial organs and the lever arm measured at the base of the plant). Data from living plants indicate that the largest arborescent plant species rely on massive trunks and broad, horizontally expansive root crowns to resist drag torques. The drag on the canopies of these plants is also reduced by highly flexible stems and leaves composed of tissues that twist and bend more easily than tissues used to stiffen older, more proximal stems. A brief review of the fossil record suggests that modifications in stem, leaf, and root morphology and anatomy capable of simultaneously coping with self-weight and wind-induced drag forces evolved by Devonian times, suggesting that natural selection acting on the elastic stability of sporophytes occurred early in the history of terrestrial plants.     

What are Backshoots Good For? Seasonal Changes in Mineral, Carbohydrate and Water Content of Different Organs of the Epiphytic Orchid, Dimerandra emarginata

The epiphytic orchid, Dimerandra emarginata (G. Meyer) Hoehne,keeps older stems (‘ backshoots’) after the attachedfoliage dies. I investigated seasonal changes in the water,carbohydrate and nutrient content of these leafless stems alongwith associated, connected organs for 1 year. Older stems significantlyincrease the water storage capacity of a plant, allowing itto tolerate long periods of drought. Reduction in total non-structuralcarbohydrates (TNC) at the beginning of the growing season indicatedan important role of carbon stored in older stems for the re-initiationof vegetative growth after the dry season, while the lack ofan increase in TNC before fruiting suggests no such role forreproduction. While seasonal fluctuations in water contentsand TNC were pronounced, concentrations of nutrients (N, P,K) showed only small seasonal variation in all vegetative organs.Allocation of carbon and nutrients to developing fruits wasrather high, exceeding, e.g. 20% of the total plant pool ofpotassium. This large investment in fruits was derived fromall vegetative organs. I conclude that persistent stems servea crucial function in the water, carbon and nutrient relationsof epiphytes such as D. emarginata, which live in habitats whereaccess to water and key nutrients is often severely limited.Copyright 1999 Annals of Botany Company Barro Colorado Island, Dimerandra emarginata, epiphytes, mineral nutrients, orchids, reproduction, resource allocation, total non-structural carbohydrates.     

Diversity of germination strategies and seed dormancy in herbaceous species of campo rupestre grasslands

The effects of fire on the vegetation vary across continents. However, in Neotropical fire‐prone grasslands, the relationship between fire and seed germination is still poorly understood, while their regeneration, especially after strong anthropogenic disturbance, is challenging for their conservation. In the present study, we assessed diversity of germination strategies in 15 dominant herbaceous species from Neotropical altitudinal grasslands (locally known as campos rupestres). We exposed seeds to several fire‐related treatments. We also compared germination between regularly and post‐fire fruiting species. Finally, we investigated the diversity of dormancy classes aiming at better understanding the biogeography and phylogeny of seed dormancy. Germination strategies varied among families. Velloziaceae and Xyridaceae produced non‐dormant, fast‐germinating seeds. Cyperaceae and Poaceae showed an extremely low or null germination due to a high proportion of unviable or embryo‐less seeds. The seeds of campo rupestre grasslands are fire resistant, but there is no evidence that fire triggers germination in this fire‐prone ecosystem. Although heat and charred wood did not promote germination, smoke enhanced germination in one grass species and decreased the mean germination time and improved synchrony in Xyridaceae and Velloziaceae. Fire had a positive effect on post‐fire regeneration by stimulating fruit set in some Cyperaceae and Poaceae species. These species produced faster germinating seeds with higher germination percentage and synchrony compared to regularly fruiting Cyperaceae and Poaceae species. This strategy of dispersion and regeneration seems to be an alternative to the production of seeds with germination triggered by fire. Physiological dormancy is reported for the first time in several clades of Neotropical plants. Our data help advance the knowledge on the role of fire in the regeneration of Neotropical grasslands.     

Do host bark traits influence trunk epiphyte communities?

Host bark traits are known to affect the characteristics of epiphyte communities in forests worldwide; however, few investigations of such relationships have been undertaken in New Zealand forests. By examining the trunk epiphyte communities on four co-occurring forest tree species (Agathis australis, Dacrydium cupressinum, Knightia excelsa and Vitex lucens) representing a range of bark characteristics, we sought evidence that bark traits may shape these communities. Sampling was conducted on tree trunks in the Waitakere and Hunua ranges in the Auckland Region. As expected, the rough but lightly shedding bark of Vitex lucens was found to support many epiphytes, whereas the coarsely flaking bark surface of Dacrydium cupressinum supported few epiphytes. Conversely, despite bark with a smooth texture that sheds in large flakes, and contrary to the suggestions of previous authors, Agathis australis trunks were found to support the greatest numbers of epiphytes and this species was one of the most frequent epiphyte hosts. The individual epiphytes found on Agathis australis, however, were significantly smaller and more appressed to the trunk than those on the other trees, and species composition differed from the other host species.