Alejandro Flores-Palacios

Host preferences of low-trunk vascular epiphytes in a cloud forest of Veracruz, Mexico

The diversity, abundance and frequency of vascular epiphytes on the lower trunk were compared between two host groups of a Mexican cloud forest: angiosperm trees (n = 72) and tree ferns (n = 28). The bark of the live most frequent host trees and the root mantle of the two tree ferns were analysed for their thickness, water content, water retention capacity and pH. A total of 5 5 epiphyte species and 910 individuals were found on the 2 7 host species. On hosts with a dbh range of 5-10 cm. epiphytes were significantly more diverse (4.3 ± 0.9 species per host) and more abundant (12.5 ± 2.2 individuals per host) on tree ferns than on angiosperm trees (1.9 ± 0.2 species per host and 3.9 ± 0.6 individuals per host). However, these differences were not significant for the dbh class of 10-20 cm, because epiphyte numbers increased on angiosperm trees with larger host size. but not in tree ferns. Most epiphyte species had no preference for any host group, but four species were significantly more frequent on tree ferns and two species on angiosperm trees. The higher epiphyte diversity and abundance on tree fern trunks of the smallest dbh class is attributed to their presumably greater age and to two stem characteristics, which differed significantly between host groups, the thicker root mantle and higher water retention capacity of tree ferns. These bark characteristics may favour germination and establishment of epiphytes.

Habitat isolation changes the beta diversity of the vascular epiphyte community in lower montane forest, Veracruz, Mexico

Habitat isolation is one of the most important factors endangering the biodiversity, but little research has been done with vascular epiphytes. In order to understand the effect of isolation on the epiphyte community, we studied epiphyte diversity on three plots in a forest fragment, two riparian forest fragments, and in isolated pastureland trees. We found 118 vascular epiphyte species. On forest plots, both epiphyte richness per tree (Stree) and species turnover rate within trees (βtree) registered the highest values, although the lowest Stree diversity was also found there; additionally inside the forest were host species with clearly different epiphyte community. Stree and βtree diversities of riparian fragments behaved similarly to those of the forest. Isolated trees had the second highest Stree diversity, although their βtree diversity was the lowest. In the forest plots were both, the highest and lowest expected accumulated richness (α diversity); on riparian fragments it was intermediate, and the second lowest α diversity was registered for isolated trees. Species turnover rate among plots (β) was high and was associated with both, isolation and a distance gradient from permanent water sources. The epiphyte community on isolated trees was clearly different to the other habitats. Results suggest that deforestation eliminated dry areas and specific hosts that were important for the maintenance of epiphyte species richness. In pastureland trees the epiphyte βtree diversity diminished, suggesting a simplification of the environment for epiphytes and causing a low α diversity.

Effect of isolation on the structure and nutrient content of oak epiphyte communities

Because isolated trees in pasture experience greater exposure than forest trees, the epiphytes on them should be more drought and sun-tolerant. In Veracruz, Mexico, we compared the structure and nutrient content of the epiphyte community on five forest oaks (FO) in a fragment of lower montane cloud forest to that of five isolated oaks in pasture (IO). IO supported fewer epiphyte species than FO; 62.8% of the 35 epiphyte species were recorded only in one habitat (51.4% on FO and 11.4% on IO). Polypodium plebeium and Tillandsia spp. seedlings were more abundant on FO, while T. kirchhoffiana and T. punctulata were more abundant on IO. Evenness was lower on IO, which supported higher epiphyte biomass. pH, Ca, Mg, N, K, and Na concentrations were similar for FO and IO, with only Pextractable being lower on IO than FO. We concluded that when an epiphyte community is isolated (IO), the populations of some species expand while those of other diminish or disappear, a phenomenon that changes the structure of the epiphyte community becoming less even.

Host preference and host limitation of vascular epiphytes in a tropical dry forest of central Mexico

It has been suggested that vascular epiphyte composition and abundance may be influenced by forest host composition. We studied the epiphyte species distribution among host species of a tropical dry forest in Mexico. All the epiphyte stands supported by woody plants (dbh > 3 cm) of ten forest plots (0.1 ha each) were counted. We measured the dbh of all the hosts, noted their bark characteristics (texture and peeling behaviour), and measured the bark thickness of the most abundant host species. Epiphyte distribution was biased toward a high concentration of epiphytes in three host species and a lower abundance of epiphytes on five host species. This was consistent among epiphyte taxa and host species, allowing us to classify hosts as preferred (with more epiphyte stands than expected by chance) and limiting species (with fewer epiphyte stands than expected by chance), at a community level. Host quality did not relate to mean phorophyte size (measured as basal area) or to bark characteristics (peeling behaviour, thickness and texture) between species. For some epiphyte taxa, the observed distribution indicated that the forest contained preferred and limiting host species mainly. Our data suggest that the epiphyte species in the forest studied could be host limited. We concluded that neither host size nor obvious bark characteristics can be used to predict epiphyte distribution and that further research is necessary.

Seed rain in a tropical agricultural landscape.

Seed dispersal into fragmented tropical landscapes limits the rate and character of ecological succession between forest remnants. In a novel experiment in recovery of dispersal between forest remnants, 120 1-m 2 seed traps were placed in fenced plots in active pasture 90-250 m from forest, and in nearby primary and secondary forests. Total seed rain from December 2006 to January 2008 included 69 135 seeds of 57 woody species. High richness of seed rain of early-successional trees occurred in all habitats, but seed rain of late-successional woody plants was much lower into pastures and secondary forest than into old-growth forest. Non-metric ordination analysis further demonstrated high movement of late-successional species within and between forest and secondary forest, but little movement of species of either forest type to pastures. Most species were dispersed by animals, but most seeds were dispersed by wind. A pattern of seed rain biased strongly towards wind-dispersed species creates a template for regeneration quite unlike that in nearby forest.

Effect of host-bark extracts on seed germination in Tillandsia recurvata , an epiphytic bromeliad

Tree species are potential hosts for epiphytes; however in some forests epiphytes have a biased distribution among hosts. In a tropical dry forest of Mexico, previous research showed that there are trees with few epiphytes. It is possible that the bark of these hosts contain allelochemicals that influence epiphyte seed germination. The aims of this study were (1) to determine whether hosts with low epiphyte abundance ( Ipomoea murucoides , I. pauciflora and Lysiloma acapulcense ) would inhibit seed germination of Tillandsia recurvata through aqueous and organic bark extracts, (2) to determine whether germination of T. recurvata would differ among the hosts with low epiphyte abundance and a host with high epiphyte abundance ( Bursera copallifera ) and (3) to relate the chemical composition of organic bark extracts with inhibition of T. recurvata seed germination. Hexanic and dichloromethanic extracts were partially chemically characterized. Total phenolics and flavonoids concentrations of methanolic extracts were analysed. Aqueous and organic bark extracts from hosts with few epiphytes inhibited T. recurvata seed germination. Aqueous and dichloromethanic extracts of B. copallifera inhibited slightly the germination of T. recurvata . There was a positive correlation between concentration of flavonoids and inhibition of seed germination. Results suggest that a combination of compounds may be responsible for affecting the germination of T. recurvata . This study demonstrates the chemical effect of aqueous and organic bark extracts from hosts on germination of an epiphytic bromeliad.

Is branch damage by xylophages related to the presence of epiphytes

Host identity influences the guilds (epiphytes and xylophages) that interact within canopies. Host species can be categorized as either limiting or preferred hosts based on epiphyte load. It is possible that, depending on the host category (limiting or preferred), galleries bored by xylophages would affect the quality and availability of space for epiphytes. The objective of this study was to determine, among and within limiting and preferred hosts, the relationship between the damage inflicted by insects to branches and epiphytic bromeliads. We collected two branches each (with and without epiphytes, respectively) from limiting hosts (Bursera fagaroides, Ipomoea murucoides and I. pauciflora) and preferred hosts (Bursera copallifera and B. glabrifolia). The variables measured were: number and species of epiphytes, number of holes, number and taxonomical group of insects, percentage of epiphyte cover and percentage of area damaged by insects. These variables were compared among and within hosts and the significant correlations, where present, determined. We identified five bromeliad species and six taxonomical groups of insects. I.murucoides showed a higher proportion of damage and a larger number of insects. For the three limiting hosts, there was a negative relationship between (1) epiphyte cover and damaged area, (2) number of epiphyte individuals and number of xylophages and (3) number of epiphyte individuals and damaged area. Within species, B. copallifera, B. glabrifolia and I. pauciflora had more holes in branches that supported epiphytes than in branches without. We hypothesized that, inter-specifically, xylophages would interfere with the establishment of epiphytes by facilitating the release of allelopathics, but this possibility needs to be examined in more detail. Intra-specifically, it is possible that holes made by xylophages do not cause sufficient damage in hosts and, consequently, a possible repercussion on epiphytes is not reflected.

Vascular epiphytes and host trees of ant-gardens in an anthropic landscape in southeastern Mexico

Ant-gardens (AGs) are considered one of the most complex mutualist systems between ants and plants, since interactions involving dispersal, protection, and nutrition occur simultaneously in them; however, little is known about the effects of the transformation of ecosystems on their diversity and interactions. In five environments with different land use within an anthropic landscape in southeastern Mexico, we investigated the diversity and composition of epiphytes and host trees of AGs built by Azteca gnava. A total of 10,871 individuals of 26 epiphytic species, associating with 859 AGs located in 161 host trees, were recorded. The diversity and composition of epiphytes tended to be different between environments; however, Aechmea tillandsioides and Codonanthe uleana were the most important species and considered true AG epiphytes, because they were the most frequent, abundant, and occurred exclusively in AGs. Other important species were the orchids Epidendrum flexuosum, Coryanthes picturata, and Epidendrum pachyrachis, and should also be considered true AG epiphytes, because they occurred almost exclusively in the AGs. The AG abundance in agroforestry plantations was similar or even greater than in riparian vegetation (natural habitat). The AGs were registered in 37 host species but were more frequent in Mangifera indica and Citrus sinensis. We conclude that true epiphytes of A. gnava AGs persist in different environments and host trees, and even these AGs could proliferate in agroforestry plantations of anthropic landscapes.

Is Allelopathic Activity of Ipomoea murucoides Induced by Xylophage Damage

Herbivory activates the synthesis of allelochemicals that can mediate plant-plant interactions. There is an inverse relationship between the activity of xylophages and the abundance of epiphytes on Ipomoea murucoides. Xylophagy may modify the branch chemical constitution, which also affects the liberation of allelochemicals with defense and allelopathic properties. We evaluated the bark chemical content and the effect of extracts from branches subjected to treatments of exclusion, mechanical damage and the presence/absence of epiphytes, on the seed germination of the epiphyte Tillandsia recurvata. Principal component analysis showed that branches without any treatment separate from branches subjected to treatments; damaged and excluded branches had similar chemical content but we found no evidence to relate intentional damage with allelopathy; however 1-hexadecanol, a defense volatile compound correlated positively with principal component (PC) 1. The chemical constitution of branches subject to exclusion plus damage or plus epiphytes was similar among them. PC2 indicated that palmitic acid (allelopathic compound) and squalene, a triterpene that attracts herbivore enemies, correlated positively with the inhibition of seed germination of T. recurvata. Inhibition of seed germination of T. recurvata was mainly correlated with the increment of palmitic acid and this compound reached higher concentrations in excluded branches treatments. Then, it is likely that the allelopathic response of I. murucoides would increase to the damage (shade, load) that may be caused by a high load of epiphytes than to damage caused by the xylophages.

Faunistic Composition of Cleridae (Coleoptera) in El Limón de Cuauchichinola, Morelos, Mexico

ABSTRACT This paper presents the first detailed faunistic study in Mexico for the family Cleridae, an important group of predatory beetles. The study was carried out in El Limón de Cuauchichinola, Tepalcingo, in the state of Morelos, Mexico, over a year of systematic collections (June 2006 to May 2007). The family Cleridae was found to be represented in the study area by seven subfamilies, 18 genera, and 44 species. The dominant genera were Phyllobaenus Dejean with nine species, followed by Cymatodera Gray with eight, and Enoclerus Gahan with seven. The nonparametric estimators Incidence Coverage Estimate, Chao2, and second-order Jacknife estimated that between 65 and 78% of the true richness was recorded. The family showed a marked seasonality, with greater richness and abundance found during the rainy season. Sweeping and beating vegetation were the most efficient collection methods, producing 71.7% of the recorded species richness. Of the species determined, 18 represent new records for Morelos and five of these are new records for the country. The results provide evidence that the tropical dry forest of the Sierra de Huautla Biosphere Reserve is an ecosystem rich in species. The new records also serve to contribute to our general knowledge of the distribution of Cleridae in Mexico.