Neither Host-specific nor Random: Vascular Epiphytes on Three Tree Species in a Panamanian Lowland Forest

• Background and Aims A possible role of host tree identity in the structuring of vascular epiphyte communities has attracted scientific attention for decades. Specifically, it has been suggested that each host tree species has a specific subset of the local species pool according to its own set of properties, e.g. physicochemical characteristics of the bark, tree architecture, or leaf phenology patterns. • Methods A novel, quantitative approach to this question is presented, taking advantage of a complete census of the vascular epiphyte community in 0·4 ha of undisturbed lowland forest in Panama. For three locally common host-tree species (Socratea exorrhiza, Marila laxiflora, Perebea xanthochyma) null models were created of the expected epiphyte assemblages assuming that epiphyte colonization reflected random distribution of epiphytes in the forest. • Key Results In all three tree species, abundances of the majority of epiphyte species (69-81 %) were indistinguishable from random, while the remaining species were about equally over- or under-represented compared with their occurrence in the entire forest plot. Permutations based on the number of colonized trees (reflecting observed spatial patchiness) yielded similar results. Finally, a third analysis (canonical correspondence analysis) also confirmed host-specific differences in epiphyte assemblages. In spite of pronounced preferences of some epiphytes for particular host trees, no epiphyte species was restricted to a single host. • Conclusions The epiphytes on a given tree species are not simply a random sample of the local species pool, but there are no indications of host specificity eithe

The economics of mandatory security breach reporting to authorities

Legislators in many countries enact security breach notification regulation to address a lack of information security. The laws designate authorities to collect breach reports and advise firms. We devise a principal–agent model to analyze the economic effect of mandatory security breach reporting to authorities. The model assumes that firms (agents) have few incentives to unilaterally report breaches. To enforce the law, regulators (principals) can introduce security audits and sanction noncompliance. However, audits cannot differentiate between concealment and nescience of the agents. Even under optimistic assumptions regarding the effectiveness of mandatory security breach reporting to authorities in reducing individual losses, our model predicts that it may be difficult to adjust the sanction level such that breach notification laws generate social benefit

Martin Mulsow, Radikale Frühaufklärung in Deutschland 1680–1720. Bd. 1: Moderne aus dem Untergrund. Bd. 2: Clandestine Vernunft. Göttingen, Wallstein 2018

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.Peer Reviewe

Long-term changes of vascular epiphyte assemblages in the tropical lowlands of Panama

The study provides insights into the dynamic processes of vascular epiphyte vegetation in two host tree species of lowland forest in Panama. Further, a novel approach is presented to examine the possible role of host tree identity in the structuring of vascular epiphyte communities: For three locally common host tree species (Socratea exorrhiza, Marila laxiflora, Perebea xanthochyma) we created null models of the expected epiphyte assemblages assuming that epiphyte colonization reflected random distribution of epiphytes in the forest. In all three tree species, abundances of the majority of epiphyte species (69 – 81 %) were indistinguishable from random, while the remaining species were about equally over- or underrepresented compared to their occurrence in the entire forest plot. Permutations based on the number of colonized trees (reflecting observed spatial patchiness) yielded similar results. Finally, a Canonical Correspondence Analysis also confirmed host-specific differences in epiphyte assemblages. In spite of pronounced preferences of some epiphytes for particular host trees, no epiphyte species was restricted to a single host. We conclude that the epiphytes on a given tree species are not simply a random sample of the local species pool, but there are no indications of host specificity either. To determine the qualitative and quantitative long-term changes in the vascular epiphyte assemblage of the host tree Socratea exorrhiza, in the lowland forest of the San Lorenzo Crane Plot, we followed the fate of the vascular epiphyte assemblage on 99 individuals of this palm species, in three censuses over the course of five years. The composition of the epiphyte assemblage changed little during the course of the study. While the similarity of epiphyte vegetation decreased on single palm individuals through time, the similarity analyzed over all palms increased. Even well-established epiphyte individuals experienced high mortality with only 46 % of the originally mapped individuals surviving the following five years. We found a positive correlation between host tree size and epiphyte richness and detected higher colonization rates of epiphytes per surface area on larger trees. Epiphyte assemblages on single Socratea exorrhiza trees were highly dynamic while the overall composition of the epiphyte vegetation on the host tree species in the study plot was rather stable. We suggest that higher recruitment rates due to localized seed dispersal by already established epiphytes on larger palms promote the colonization of epiphytes on larger palms. Given the known growth rates and mortality rates of the host tree species, the maximum time available for colonization and reproduction of epiphytes on a given Socratea exorrhiza tree is estimated to be about 60 years. Changes in the epiphyte vegetation of c. 1000 individuals of the host tree species Annona glabra at Barro Colorado Island over the course of eight year were documented by means of repeated censuses. Considerable increase in the abundance of the dominating epiphyte species and ongoing colonization of the host tree species suggests that the epiphyte vegetation has not reached a steady state in the maximal 80 years since the establishment of the host tree. Epiphyte species composition as a whole was rather stable. We disentangled the relationship between epiphyte colonization and tree size/available time for colonization with the finding that tree size explained only a low proportion of colonization while other factors like connectivity to dispersal source and time explain may explain a larger part. Epiphyte populations are patchily distributed and examined species exhibit properties of a metapopulation with asynchronous local population growth, high local population turnover, a positive relationship between regional occurrence and patch population size, and negatively correlated relationship between extinction and patch occupancy. The documented metapopulation processes highlight the importance of not colonized suitable habitat for the conservation of epiphytes.Langzeitveränderungen von vaskulären Epiphytengemeinschaften im tropischen Tiefland von Panam

Ulrich Muhlack, Renaissance und Humanismus. (Enzyklopädie deutscher Geschichte, Bd. 93.) Berlin/Boston, De Gruyter 2017

Dieser Beitrag ist mit Zustimmung des Rechteinhabers (De Gruyter) frei zugänglich.Peer Reviewe

Geschäftsinteresse statt ethnischer Identität? Unternehmer von Lódz im 19. Jahrhundert

The example of the metropole of textile industries in Poland gives us new facts on the weight of ethnic patterns in business´ life. This paper put stress on the mentalities and activities of textile barons in their careers as entrepreneurs, who were most of german or jewish origin. In Lodz, where the rasant capitalist change produced above all a field of economic expansion and technical improvment and where the central governmental power was far away the fabricants began more or less under the same conditions undisturbed of indigenous structures. Ethnical or national belongings disappeared more and more behind the contemporary slogan of „Lodzer Mensch“, who represented a „fin de siècle – businessman“ on the peak of capitalism

Christine Christ-von Wedel, Glaubensgewissheit und Gewissensfreiheit. Die frühe Reformationszeit in Basel. (Colmena Perspektiven, Bd. 3.) Basel, Colmena Verlag 2017

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.Peer Reviewe