Richness and occupancy patterns of epiphyll bryophytes in a fragmented landscape of tropical rain forests in northeastern Brazil (Murici Ecological Station) were investigated to assess the influence of regional and local disappearance of habitat on epiphyllous metapopulation indicators. Bryophytes were collected from ten forest fragments, from the fragment's border to 100 m inside the forest. The number of colonized phorophytes and the cover on leaves were scored. Decreasing trends in regional and local abundance linked to habitat loss were observed, which may be related to the sexual and asexual expression. Although fertility was not related to constancy in the fragments, frequently fertile species colonized more sites within fragments than infertile species. Landscape metrics and indicators of habitat quality explained better the variation in epiphyll richness and occupancy than distance from the forest's edge. This suggests that the abrupt habitat quality modification resulting from edge creation is secondary in the area studied, while irreversible landscape modifications still play an important role. The results add to empirical support that metapopulations are prone to negative and long-term effects in fragmented landscapes. Thus, the selection of priority areas for conservation must take into account the remaining amount of habitat as well as the connectivity between the landscape's patches.Abstract in Portuguese is available at

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 0 05 00 -9°16 0 48 00 S, 35°45 0 20 00 -35°55 0 12 00 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.

Summary 1.We test how fine-scale (£ 400 m 2 ) connectivity to conspecifics influences metapopulation dynamics using a field experiment in central Amazonia with the epiphyllous (i.e. leaf-inhabiting) bryophyte Radula flaccida Gott. (Radulaceae). This is a natural model system with spatially structured ephemeral patches at the leaf and phorophyte scale. 2. The aim was to test how the rates of leaf colonization, local abundance, growth and extinction of bryophytes from both leaves and host phorophytes were affected by experimentally manipulated variation in connectivity to conspecifics. We also investigated the relative importance of local stochastic extinctions and deterministic extinctions at both spatial scales.3. Approximately 3500 leaves on 70 phorophytes were censused six times over a 15-month period by utilizing a repeated block design with control, positive control and three pulse-style reduction treatments, which varied in connectivity to surrounding conspecifics.4. An increase in stochastic extinction events was only accompanied by a reduction in colonization in the treatment in which focal and neighbouring phorophytes within the 400 m 2 plots were experimentally denuded of their natural populations, suggesting that epiphyllous cryptogams are subject to fine-scale (within phorophyte) rescue effects. Negative density-dependent growth was also detected in within-leaf population dynamics, suggesting that resource limitation or intraspecific competition influences local population growth. Finally, stochastic extinctions from viable leaves occurred with nearly the same frequency as deterministic events (e.g. leaf fall), whereas at the phorophyte scale only stochastic extinctions were observed. 5. Synthesis. The experiment demonstrates that rescue effects occur at fine scales even for vagile plant taxa, such as cryptogams, which may inhabit spatially isolated substrates characterized by turnover rates as fast as their own population dynamics. Furthermore, the results highlight the importance of quantifying both stochastic and deterministic extinction modes, as underestimating either of these parameters leads to over optimistic projections of future metapopulation size.

In order to investigate which mechanisms the epiphyllous moss Crossomitrium patrisiae employs to overcome the typical constraints of dioicy in light of its spatially isolated habitat, we tested the predictions that high fertilization rates are achieved due to (1) high rates of sexual expression, (2) balanced sex ratios, and (3) high co-occurrence of both sexes in the same colony (leaf). Seven hundred and ninety-seven ramets were studied for total length, presence, and number of gametoecia and number of fertilized perichaetia in the female according to spatial segregation at leaf-and shrub-scales. High rates of sexual expression (76%) were confirmed. The other two predictions, however, were not upheld as C. patrisae exhibited a strong male bias (0.43 R : 1 = at ramet level, n5604). Despite considerable spatial segregation (co-occurrence of sexes was seen in 36.7% of shrubs and 12.8% of colonies), this species revealed one of the highest fertilization rates ever reported for a dioicous bryophyte at three spatial scales: nearly 90% of the mixed colonies bore sporophytes, 40% of all female ramets, and 74% of female ramets occurring in mixed colonies bore sporophytes. Thus, the relative rareness of females may be a phenotypic response due to heavy investment in sporophyte maturation as demonstrated by the high fertilization success of females. High rates of sexual expression and the occurrence of fertilization in nearly all cases of coincidence of sexes in common colonies, with low levels of abortion, contribute to the sexual reproductive success and, subsequently, the long-term survival of this species. Journal of Bryology 2013 VOL. 35 NO. 2 Alvarenga et al. Crossomitrium patrisiae sex ratio, spatial segregation, and fertilization rates Journal of Bryology 2013 VOL. 35 NO. 2 Alvarenga et al. Crossomitrium patrisiae sex ratio, spatial segregation, and fertilization rates Journal of Bryology 2013 VOL. 35 NO. 2 Alvarenga et al. Crossomitrium patrisiae sex ratio, spatial segregation, and fertilization rates Journal of Bryology 2013 VOL. 35 NO. 2

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