Gerhard Zotz

Carl von Ossietzky Universität Oldenburg · Department of Biology and Environmental Sciences (IBU)

The epiphytic orchid Caularthron bilamellatum sacrifices its water storage tissue for nutrients from the waste of ants lodging inside its hollow pseudobulb. Here, we investigate whether fungi are involved in the rapid translocation of nutrients. Uptake was analysed with a 15N labelling experiment, subsequent isotope‐ratio mass spectrometry (IRMS) a...

Background and Scope The epiphytic life form characterizes almost 10 % of all vascular plants. Defined by structural dependence throughout their life and their non-parasitic relationship with the host, the term epiphyte describes a heterogenous and taxonomically diverse group of plants. This article reviews the importance of crassulacean acid metab...

Here we provide the ‘Global Spectrum of Plant Form and Function Dataset’, containing species mean values for six vascular plant traits. Together, these traits –plant height, stem specific density, leaf area, leaf mass per area, leaf nitrogen content per dry mass, and diaspore (seed or spore) mass – define the primary axes of variation in plant form...

The Bromeliaceae family has been used as a model to study adaptive radiation due to its terrestrial, epilithic, and epiphytic habits with wide morpho-physiological variation. Functional groups described by Pittendrigh in 1948 have been an integral part of ecophysiological studies. In the current study, we revisited the functional groups of epiphyti...

Tank bromeliads are unique canopy microhabitats that offer freshwater and organic nutrient-rich substrates in the Neotropics. In them it is possible to thoroughly characterize environmental factors and species composition of terrestrial and aquatic biota. Therefore, these plants have been used as natural models to study how communities are distribu...

Premise: Approximately 14% of all fern species have physiologically active chlorophyllous spores that are much more short-lived than the more common and dormant achlorophyllous spores. Most chlorophyllous-spored species (70%) are epiphytes, and these account for almost 37% of all epiphytic ferns. Chlorophyllous-spored ferns are also overrepresente...

Climate change is a mounting global issue, but its consequences will be variable across regions. Tropical species are hypothesized to have reduced climatic adaptability and plasticity. Yet, relative to temperate species, less is understood about how they will respond to climate change. Rising temperature and atmospheric CO2 could impact plant–herbi...

Background and Aims: In the roots of most vascular plants, the growth zone is small, the meristem and the elongation zone are sharply separated, and only meristematic cells divide. This statement is based almost entirely on studies with soil-rooted plants. Whether aerial roots of structurally dependent (=epiphytic/hemiepiphytic) species differ is v...

El término hemiepífitas ha sido usado para las aráceas y otras trepadoras (p.ej. Clusia, Ficus), a veces distinguiendo entre hemiepífitas primarias (HP) y secundarias (HS) como formas de crecimiento diferentes. (Putz y Holbrook 1986; Gentry y Dodson 1987; Nadkarni et al. 2001). Las HP germinan y pasan su estado juvenil como epífitas y posteriorment...

Variation in leaf functional traits along environmental gradients can reveal how vascular epiphytes respond to broad‐ and small‐scale environmental gradients. Along elevational gradients, both temperature and precipitation likely play an important role as drivers of leaf trait variation, but these traits may also respond to small‐scale changes in l...

Premise: For vascular epiphytes, secure attachment to their hosts is vital for survival. Yet studies detailing the adhesion mechanism of epiphytes to their substrate are scarce. Examination of the root hair-substrate interface is essential to understand the attachment mechanism of epiphytes to their substrate. This study also investigated how subs...

As climate change leads to increasing temperatures, tropical dry seasons are expected to become more severe. An overall intensification of drought events may strongly affect vascular epiphytes. Especially at the community level, the response of epiphytes to intense drought events is still poorly understood. Therefore, the severe El Niño event of 20...

Vascular epiphytes are an important component of many ecosystems and constitute a substantial part of global plant diversity. In this context, accidental epiphytism, i.e. the opportunistic epiphytic growth of typically terrestrial species, deserves special attention as it provides crucial insights into the global distribution of vascular epiphytes...

Many bromeliads occur in habitats that are potentially affected by salt. Pitcairnia halophila is a particularly interesting case in this context due to its growing sites in the spray zone of coastal cliffs in Central America. We conducted an experimental/observational study that explored the physiological and ecological basis of the occurrence of t...

Several studies of hurricane damage on epiphyte communities implied that epiphytes might be in danger of being blown off their host when subjected to strong wind. There is very limited knowledge about the mechanical impact that wind may have on epiphytes. Using a wind-triggered camera set-up, we observed how epiphytic tank bromeliads are affected b...

With over a millennium history of cultivation, Cymbidium species and hybrids is one of the most commercially important orchids in world floriculture industry. The Cymbidium genus has near 75 species with ornamental and medicinal importance and thousands of hybrids used for pot and cut flower production. Plant tissue culture techniques for breeding...

Habitat heterogeneity is considered a primary causal driver underpinning patterns of diversity, yet the universal role of heterogeneity in structuring biodiversity is unclear due to a lack of coordinated experiments testing its effects across geographic scales and habitat types. Furthermore, key species interactions that can enhance heterogeneity,...

Future climate‐change effects on plant growth are most effectively studied using microclimate‐manipulation experiments, the design of which has seen much advance in recent years. For tropical forests, however, such experiments are particularly hard to install and have hence not been widely used. We present a system of active heating and CO2 fertili...

Vascular epiphytes represent almost 10% of all terrestrial plant diversity. Despite the extensive research on the functional ecology and challenges of epiphytic growth, there is still very little known on how exposure to mechanically induced stress affects the growth and development of epiphytes. Therefore, this study investigated the effect of suc...

Bromeliads are the most abundant litter-trapping plants in Neotropical forest canopies. By intercepting litter, bromeliads obtain and retain nutrients before they reach the pedosphere. Here, we analyzed the litter captured and stored by tank bromeliads (TB) in five different forests along an elevation gradient in Mexico. Among those forests, carbon...

Plants and animals evolve different attachment structures and strategies for reversible or permanent adhesion to different substrate types. For vascular epiphytes, having the ability to permanently attach to their host plants is essential for establishment and survival. Unlike mistletoe roots, roots of vascular epiphytes do not penetrate the host t...

The epiphytic life form characterizes almost 10% of all vascular plants. Defined by their mechanical dependence throughout their life and their non‐parasitic relationship with the host, the term epiphyte describes a very heterogenous and taxonomically diverse group of plants. This article explores the functional ecology of this group, acknowledging...

Understanding the degree to which deterministic and stochastic processes drive community assembly is an ongoing focus of research in community ecology. This effort is strongly biased towards ground‐rooted plants, resulting in a limited understanding of communities of other life forms, such as structurally dependent plants. Vascular epiphytes are se...

This data paper describes a new, comprehensive database (BIOVERA-Epi) on species distributions and leaf functional traits of vascular epiphytes, a poorly studied plant group, along gradients of elevation and forest-use intensity in the central part of Veracruz State, Mexico. The distribution data include frequencies of 271 vascular epiphyte species...

For decades, tropical ecologists distinguished primary (PH) and secondary hemiepiphytes (SH) as two structurally dependent life forms with an epiphytic phase at, respectively, the beginning or the end of their ontogeny. However, the use of these terms has been criticized repeatedly because the term “hemiepiphyte” suggests an unsubstantiated biologi...

Aim Vascular epiphytes are ubiquitous components of wet tropical forests where they contribute substantially to local and regional plant diversity. While some basic epiphyte distribution patterns are relatively well studied, little effort has been made to understand the drivers responsible for constraining their global distribution. This study quan...

Plant functional traits impact the fitness and environmental niche of plants. Major plant functional types have been characterized by their trait spectrum, and the environmental and phylogenetic imprints on traits have advanced several ecological fields. Yet very few trait data on epiphytes, which represent almost 10% of vascular plants, are availa...

Tropical forests are the most diverse terrestrial ecosystems and home to numerous tree species competing for resources in space and time. Functional traits influence the ecophysiological performance of tree species, yet the relationship between traits and emergent long-term growth patterns is poorly understood. Here, we present a novel 3D forest st...

Metacommunity ecology currently lacks a consistent functional trait perspective across trophic levels. To foster new cross‐taxa experiments and field studies, we present hypotheses on how three trait dimensions change along gradients of density of individuals, resource supply and habitat isolation. The movement dimension refers to the ability to mo...

This data paper describes a new, comprehensive database (BIOVERA-Epi) on species distributions and leaf functional traits of vascular epiphytes, a poorly studied plant group, along gradients of elevation and forest-use intensity in the central part of Veracruz State, Mexico. The distribution data includes frequencies of 271 vascular epiphyte specie...

Vascular epiphytes represent almost 10% of all terrestrial plant diversity. Being structurally dependent on trees, epiphytes live at the interface of vegetation and atmosphere, making them susceptible to atmospheric changes. Despite the extensive research on vascular epiphytes, little is known about wind disturbance on these plants. Therefore, this...

Hemiepiphytic plants are defined by their ontogeny. They germinate on a host tree but later establish root contact with the soil. Most hemiepiphytes remain structurally dependent on their host for their entire life, but some, often referred to as stranglers, develop pseudotrunks that allow them to outlive their host. Unfortunately, the terminology...

Vascular epiphytes represent almost 10% of all terrestrial plant diversity. Despite their growing sites exposed to frequent extensive storms, nothing is known about how external mechanical perturbations by wind affects epiphytes’ growth and development. Therefore, this study investigated the effect of such mechanical stress on the growth rate and m...

Endophytic fungi are known to be present in roots of salt marsh plants, but their ecological role in this symbiosis is still largely unknown. Generally considered parasitic or saprophytic, they may still be mutualistic, at least under certain circumstances. Among salt marsh plants, Salicornia spp. are recognized as particularly salt-tolerant and th...

Aim Vascular epiphytes are ubiquitous features of wet tropical forests where they contribute substantially to local and regional plant diversity. While some basic epiphyte distribution patterns are relatively well studied, little effort has been made to understand the drivers responsible for constraining their global distribution. This study quanti...

Background and Aims: The species of Araceae are known for their diversity of life forms; however, the terminology regarding this group generates conceptual confusion within the scientific community. Our objective was to demonstrate the current conceptual confusion based on the literature, herbarium vouchers vs. observations and field data. Methods...

Bromeliads are recognized as vital habitats for arboreal amphibians. However, these plants are often not included in traditional amphibian surveys. Furthermore, focused canopy sampling techniques are time-consuming, require specialized equipment and training, and, in the case of bromeliads, sampling is typically destructive. In this study, we devel...

Lower montane tropical forests are typically characterized by substantial epiphyte loads. One of the important ecological roles of epiphytes in these forest systems is the interception of rainwater with a major impact on forest hydrology. Several morphological traits of epi-phytes assure a dependable water supply and greatly increase the water-hold...

• Forest canopies play a crucial role in structuring communities of vascular epiphytes by providing substrate for colonization, by locally varying microclimate, and by causing epiphyte mortality due to branch or tree fall. However, as field studies in the three‐dimensional habitat of epiphytes are generally challenging, our understanding of how for...

Epiphytes make up roughly 10% of all vascular plant species globally and play important functional roles, especially in tropical forests. However, to date there is no comprehensive list of vascular epiphyte species. Here, we present EpiList 1.0, the first global list of vascular epiphytes based on standardized definitions and taxonomy. We include o...

Trait matching between interacting species may foster diversity. Thus, high epiphyte diversity in tropical forests may be partly due to the high diversity of trees and some degree of host specificity. However, possible trait matching between epiphyte and host is basically unexplored. Since the epiphytic habitat poses particular challenges to plants...

1. Despite the ecological importance of vascular epiphytes in the tropics, even basic information on the processes that form epiphyte communities is scarce. This is partially due to an almost complete lack of long‐term studies. 2. Here, we present data that was collected in three consecutive censuses over 21 years in a monospecific host tree system...

Ongoing destruction of tropical forests makes isolated pasture trees potentially important for the persistence of original forest dwellers such as many vascular epiphytes. We studied epiphyte assemblages on 100 isolated trees at ten pasture sites in southwest Panama along an elevational gradient ranging from 140 to 1240 m a.s.l. We analysed epiphyt...

The extraordinary diversity of orchids has captivated scientists for more than a century, yet their complex spatial patterns at large scales remain poorly resolved. On islands, orchid diversity patterns are especially puzzling. While some islands are centres of orchid diversity, orchids are underrepresented on most islands. To disentangle such comp...

en Despite their unique adaptations to thrive in canopy environments without access to soil resources, epiphytes are underrepresented in studies of functional traits and of functional composition of tropical plant communities. We investigated functional traits of spermatophytic (seed‐bearing) C3 and CAM epiphyte communities in flooded and non‐flood...

Vascular epiphytes in temperate zones are allegedly rare due to climatic constraints, such as drought and freezing temperatures during winter. Here, we investigate how abundance and seasonal growth of epiphytic polypod ferns in Western Europe are influenced by annual rainfall and temperature. We recorded abundances and growth of epiphytic polypod f...

Plant litter decomposition is a key ecological process that is mostly studied at the forest floor. However, decomposition generally starts in the canopy. In this study, we evaluated the effect of litter composition and climate on the initial phase of decomposition in the soil and two contrasting types of canopy microsites along an elevational gradi...

Aroids are well-known for their diversity of life forms. Unfortunately, the use of pertinent terminology on vouchers, in floras and in journal publications is highly inconsistent. We document the current situation and show that it is currently difficult to impossible to decide whether the reported variation in life forms of a given taxon reflects t...

The tropics of the New World are a biodiversity hotspot, the genus Anthurium being an example of a megadiverse taxon with currently > 1000 described species. In this study, we provide detailed information on species distributions and analyse patterns of diversity and endemism, with a particular focus on the comparison of epiphytic and terrestrial c...

Vascular epiphytes are mainly associated with tropical and subtropical forest ecosystems. However, the frequent occurrence of accidental epiphytes in temperate forests proves that epiphytic growth of vascular plants is possible in tree crowns at these latitudes. Comparing the abiotic conditions of epiphytic and terrestrial microhabitats in conjunct...

The tropics of the New World are a biodiversity hotspot, the genus Anthurium being an example of a megadiverse taxon with currently > 1000 described species. In this study, we provide detailed information on species distributions and analyse patterns of diversity and endemism, with a particular focus on the comparison of epiphytic and terrestrial c...

Tropical forests are the most diverse terrestrial ecosystems and home to numerous tree species with diverse ecological strategies competing for resources in space and time. Functional traits influence the ecophysiological performance of tree species, yet the relationship between traits and emergent long-term growth pattern is poorly understood. Her...

Premise of research: Although the term “pseudobulb” has been used in the literature on Orchidaceae for almost two centuries, no definition establishes unambiguous criteria to distinguish such a succulent shoot from a normal stem. It is currently impossible to decide whether variation is continuous rather than categorical. Methodology: We studied th...

Background: Accidental epiphytism is common among vascular plants in forest ecosystems around the globe. A frequent observation in surveys of accidental epiphytes is the occurrence of few species with high epiphytic abundance, while most co-occurring terrestrial species are rarely found as epiphytes. Aims: Based on the general assumption that water...

Vascular epiphytes form a diverse group of almost 30 000 species, yet theory concerning their community structure is still largely lacking. We therefore employed the simplest models of biodiversity, (near‐)neutral models, to generate hypotheses concerning their community structure. With recently developed tools for (near‐)neutral models we analyzed...

Tank bromeliads are prominent and distinctive components of many Neotropical forests. Functionally important for the plants themselves these phytotelms also represent important freshwater habitats in the forest canopy for a range of animal species and other biota. Existing literature values of the amount of water held in these tanks have never been...

Vascular epiphytes are a diverse and conspicuous component of biodiversity in tropical and subtropical forests. Still, the patterns and drivers of epiphyte assemblages are poorly studied in comparison to soil‐rooted plants. Our current knowledge about diversity patterns of epiphytes mainly stems from local studies or floristic inventories, but this...

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research sp...

The chemical composition of the cell walls strongly affects water permeability and storage in root tissues. Since epiphytic orchids live in a habitat with a highly fluctuating water supply, the root cell walls are functionally important. In the present study, we used histochemistry and immunocytochemistry techniques in order to determine the compos...

Aim Understanding patterns of tropical plant diversity and their vulnerability to anthropogenic disturbance at different spatial scales remains a great challenge in ecology and conservation. Here, we study how the effects of forest‐use intensity on vascular epiphyte diversity vary along a tropical elevational gradient. Location 3,500‐m elevational...

The number of available sites for establishment is a key determinant of species richness on habitat islands. While most theoretical studies assume habitat size or capacity to be constant, many natural habitats are characterized by dynamic growth in capacity over ecological timescales. A case in point is provided by trees that serve as habitat for v...

1. The forest canopy is home to a rich biota. One salient feature are the dynamics of the habitat‐building trees, which are growing and eventually vanishing. Tree species strongly differ in growth rates, final size and longevity. Nevertheless, these inherent dynamics have been a blind spot in studies on host specificity of vascular epiphytes (vascu...

Root morphology is expected to respond to environmental conditions. Two earlier studies reported predictable changes in the structure of the velamen radicum (common in monocotyledons) along rainfall gradients, which was expected from its assumed role in plant-water-relations. The present study expanded on this idea by analysing nine root traits tha...

By the year 2100, temperatures are predicted to increase by about 6 °C at higher latitudes and about 3 °C in the tropics. In spite of the smaller increase in the tropics, consequences may be more severe because the climatic niches of tropical species are generally assumed to be rather narrow due to a high degree of climatic stability and higher nic...

Questions Vascular epiphytes make up about 9 % of all vascular plants globally but are clearly underrepresented in the temperate zones. The accidental epiphytic occurrence of terrestrial species, in contrast, is common at these latitudes and can provide important insights in the evolution of obligate epiphytes. Here we present the results of the fi...