Thorsten Krömer

Species richness and habitat diversification of bryophytes in submontane rain forest and fallows of Bolivia

An analysis of corticolous bryophyte diversity on whole trees in primary rain forest and 4-15-y-old fallows at 500-650 m in the Alto Beni, Bolivia, showed a significantly decreased diversity of bryophyte families and moss species in the fallows. However, liverwort diversity was scarcely lower in the fallows, except in the very young (4 y old) ones. Fallows had a significantly higher percentage of smooth mat species (72%), which may reflect the warmer, drier microclimate in the fallows. About half of the bryophyte species of the rain forest had re-established in the 10- 15-y-old fallows. The majority of these are ecological generalists and sun epiphytes; a small minority are shade epi- phytes. Re-establishment of ecological specialists is slower than that of generalists. Species richness in the primary forest is highest in the canopy; in the fallows it is highest in the understorey due to striking shifts of species and specialized growth types (rough mats, fans, tails) towards lower heights on the trees in the fallows. These shifts corre- spond well with measured changes in air temperature and air humidity in the fallows as compared with the forest.

Nectar sugar composition and concentration in relation to pollination syndromes in Bromeliaceae

A first comprehensive dataset of nectar sugar composition and concentration in Bromeliaceae is presented, covering 111 species belonging to all three subfamilies. Based on this dataset, we examined the relationship between nectar traits and pollination syndromes in the family. Sugars in samples were assayed by high pressure liquid chromatography. All sampled species were grouped into three broad categories (trochilophilous, chiropterophilous, or lepidopterophilous) according to their main pollination mode. Significant differences between the different pollination syndromes were found in nectar sugar composition as well as concentration. For a total of four genera (Guzmania, Pitcairnia, Tillandsia and Vriesea), a comparison of nectar composition showed significant differences between trochilophilous and chiropterophilous species. Data presented here indicate that the characteristics of nectar in Bromeliaceae are predominantly determined by putative adaptations of nectar sugars to preferences of the pollinators rather than by phylogenetic relations.

Diversity patterns of ferns along elevational gradients in Andean tropical forests

Background: Biodiversity is perceived to decline from lowlands towards mountain peaks and away from the Equator towards the Poles, but supporting data for most groups of organisms are lacking, especially at the local scale. Aims: Elevational gradients of fern species richness in tropical forest habitats were analysed to test the hypotheses that fern species composition patterns were similar between elevational gradients, that total species richness of complete elevational gradients gradually declined due to changing climatic conditions with increasing distance from the Equator, and that the elevation of highest species richness gradually declined with increasing latitude. Methods: We used plot-based elevational fern species richness surveys compiled from recent field work and own published studies, between 18° N and 18° S along the Andean mountain range, and compared the transects of patterns of species richness and composition, and distribution of taxa. Results: Taxonomic composition was highly similar among tropical regions. Elevational richness patterns were symmetrically hump-shaped and overall richness was virtually equal along most of the tropical latitudinal gradient. In contrast, the subtropical localities at the edges of our study area, ca. 18° N and 18° S, showed strikingly different patterns from those in the tropical zone. Conclusions: Within the tropics, there appears to be no latitudinal diversity gradient of ferns at the local scale. We suggest that, in tropical habitats, species richness of ferns at the local scale is limited by the number of species that can co-occur and that the available niche space is saturated.

Ecoregional distribution of potentially useful species of Araceae and Bromeliaceae as non-timber forest products in Bolivia

In Bolivia, the plant families Araceae and Bromeliaceae offer numerous non-timber products, including ornamental plants, medicines, foods, and fibers. The economic potential for the utilization of these resources depends critically on the distribution of potentially useful species in different ecoregions in Bolivia. We conducted both a bibliographical revision of uses and ecological field work at 43 sites in the Bolivian Andes and lowlands to assess the potential for sustainable use as suggested by the Rapid Vulnerability Assessment method. The ecological criteria used for the evaluation were abundance (frequency), life form, geographical distribution, and habitat preference. We found that Bolivia has a striking number of potentially useful species of both families but that their potential use differs among ecoregions. Araceae were most species-rich and frequent in the humid lowland and montane forests. In these ecoregions, this family has a particular local importance mainly as traditional medicines and a great potential as ornamental plants. In contrast, economically useful bromeliads are best represented in seasonally dry forest habitats, especially for the production of fibres. Many species of bromeliads, which also occur in humid montane forests, although rare, are potentially important for commercialisation as ornamental species. This study shows that the uses of Araceae and Bromeliaceae are manifold and could be greatly increased through efficient management, although with different strategies according to the different ecoregions.

Distribution and conservation status of Phlegmariurus (Lycopodiaceae) in the state of Veracruz, Mexico

The fern and lycophyte flora of Mexico contains 13 species in the genus Phlegmariurus (Lycopodiaceae; club moss family), of which nine are found in the state of Veracruz (P. cuernavacensis, P. dichotomus, P. linifolius, P. myrsinites, P. orizabae, P. pithyoides, P. pringlei, P. reflexus, P. taxifolius). They are located primarily in undisturbed areas of humid montane, pine-oak and tropical humid forests, which are all ecosystems threatened by deforestation and fragmentation. The objective of this study was to evaluate and understand the distribution and conservation status of species of this genus in the state of Veracruz, Mexico. Using Maxent, probability distributions were modeled based on 173 herbarium specimens (25% from recent collections by the authors and/or collaborators), considering factors such as climate, elevation and vegetation cover. Additionally, anthropogenic impacts on the original habitat of each species were analyzed in order to assign threatened categories based on IUCN classifications at regional levels. Results show that potential distributions are located in the montane regions of the central and southern parts of the state. All nine Phlegmariurus species in Veracruz were found to be in some category of risk, with P. orizabae classified as critically endangered, having only a single specimen collected in 1854. The main reasons for species threats are the continuous loss and fragmentation of their natural habitat, uncontrolled harvesting activities, and the lack of protected areas that include humid montane and pine-oak forests in the central region of the state.

A Decade of New Pteridophyte Records for the State of Veracruz, Mexico

Abstract Veracruz, with 542 recorded species, is the third richest state in Mexico in terms of total fern diversity. Field work, herbarium studies, and a revision of literature during the last decade revealed 22 new state records. Five of these belong to Elaphoglossum, four are filmy ferns, and three are grammitids. Most of the new taxa were collected in the endangered humid montane and pine-oak forests of the central and Los Tuxtlas area during recent research projects. Another 13 species, mainly within Elaphoglossum and Selaginella, have been published as new records in the literature. Whereas several of these might possibly be confirmed in the future, others form part of poorly known species complexes that require specific studies, and we consider them as doubtful or unverified. Our study highlights the need of more fern inventories in remote and mostly unexplored areas, as well as revisions of national and local herbaria, both of which may reveal additional species new to science or range extensions.

First record of bat-pollination in the species-rich genus Tillandsia (Bromeliaceae)

BACKGROUND AND AIMS Bromeliaceae is a species-rich neotropical plant family that uses a variety of pollinators, principally vertebrates. Tillandsia is the most diverse genus, and includes more than one-third of all bromeliad species. Within this genus, the majority of species rely on diurnal pollination by hummingbirds; however, the flowers of some Tillandsia species show some characteristics typical for pollination by nocturnal animals, particularly bats and moths. In this study an examination is made of the floral and reproductive biology of the epiphytic bromeliad Tillandsia macropetala in a fragment of humid montane forest in central Veracruz, Mexico. METHODS The reproductive system of the species, duration of anthesis, production of nectar and floral scent, as well as diurnal and nocturnal floral visitors and their effectiveness in pollination were determined. KEY RESULTS Tillandsia macropetala is a self-compatible species that achieves a higher fruit production through outcrossing. Nectar production is restricted to the night, and only nocturnal visits result in the development of fruits. The most frequent visitor (75 % of visits) and the only pollinator of this bromeliad (in 96 % of visits) was the nectarivorous bat Anoura geoffroyi (Phyllostomidae: Glossophaginae). CONCLUSIONS This is the first report of chiropterophily within the genus Tillandsia. The results on the pollination biology of this bromeliad suggest an ongoing evolutionary switch from pollination by birds or moths to bats.

Conservation value of disturbed and secondary forests for ferns and lycophytes along an elevational gradient in Mexico

Questions How do species richness and composition of fern assemblages change with elevation and, within elevational belts, in differently impacted forest habitats? Is there a relationship between fern assemblages and microclimate, both along gradients of elevation and disturbance? Which species are most sensitive to habitat disturbance and microclimatic changes? Location The transect starts at sea level close to the Gulf of Mexico and ends 81 km away in a direct line on the eastern slopes of the Cofre de Perote at 3500 m, in central Veracruz, Mexico. Methods We studied the richness and composition of fern assemblages in 120 study plots at eight elevations at 20-3500 m in three forest types: natural forest (NF), disturbed forest (DF) subjected to timber extraction and grazing, and secondary forest (SF) regrown after total clearance 15-20 years ago. In addition, we measured microclimatic conditions in the three forest types at five elevations over a year. Results Fern richness peaked in humid montane forests at mid-elevations and was low in the dryer habitats at the ends of the gradient. Humid montane forests were most sensitive to disturbance, showing increases in mean annual temperatures by about 1°C and reduction in relative air humidity by about 20% in DF and SF compared to NF. This went along with a reduction of fern species richness by 5-60% and marked changes in species composition. In contrast, drought-deciduous forests at low elevations and coniferous forests at high elevations already had low humidity and high light intensity in NF and were less affected by human impact: Their microclimatic conditions and fern assemblages did not change markedly in DF and SF. Conclusions The conservation of much of the humidity-dependent biota (ferns and presumably also groups such as bryophytes and amphibians) in humid montane forests depends on the protection of natural fragments without human disturbance. In contrast, the naturally open forests at the ends of the gradient can be subjected to some exploitation while conserving much of their fern flora as long as a general forest structure is maintained. This article is protected by copyright. All rights reserved.

Pollen consumption by free-living mice

We present the first evidence of mice actively searching and consuming the pollen of Bromeliaceae and describe this behavior for the first time based on video-recorded evidence in the wild. Following repeated observations of nocturnal florivory in several individuals of Tillandsia macropetala, mice of the genus Peromyscus were recorded consuming pollen from this bromeliad during the dry season in the tropical montane cloud forest of central Veracruz, Mexico. The mice first consumed the anthers and, although it also consumed part of the filaments, the majority of these were discarded once the mice had consumed the pollen. The mice seem to be opportunistic consumers of pollen in a season when other resources are possibly scarce. It would be of value to determine the proportion of the rodent diet represented by pollen and other floral products during periods of low food availability, as well as to determine the potential impact of such herbivory on plant reproductive success.

Thelypteris Tuxtlensis (Thelypteridaceae), a New Species in Subgenus Goniopteris from Los Tuxtlas, Veracruz, Mexico

ABSTRACT We describe and illustrate Thelypteris tuxtlensis, a new species in subgenus Goniopteris (Thelypteridaceae), from the biogeographic region of Los Tuxtlas, in the state of Veracruz, Mexico. This species appears to be most closely related to T. hatchii and T. biolleyi.