Costly arbitrage and asset prices: evidence from closed-end funds

If arbitrage is costly and noise traders are active, asset prices may deviate from fundamental values for long periods of time. We use a sample of 158 closed-end funds to show that noise-trader sentiment, as proxied by retail-investor flows, leads to fluctuations in the discount. Nevertheless, we reject the hypothesis that noise-trader risk is the cause of the long-run discount. Instead we find that funds which are more difficult to arbitrage have larger discounts, due to: (i) the censoring of the discount by the arbitrage bounds, and (ii) the freedom of managers to increase charges when arbitrage is costly

Extinction risk of Mesoamerican crop wild relatives

Ensuring food security is one of the world's most critical issues as agricultural systems are already being impacted by global change. Crop wild relatives (CWR)—wild plants related to crops—possess genetic variability that can help adapt agriculture to a changing environment and sustainably increase crop yields to meet the food security challenge. Here we report the results of an extinction risk assessment of 224 wild relatives of some of the world's most important crops (i.e. chilli pepper, maize, common bean, avocado, cotton, potato, squash, vanilla and husk tomato) in Mesoamerica—an area of global significance as a centre of crop origin, domestication and of high CWR diversity. We show that 35% of the selected CWR taxa are threatened with extinction according to The International Union for Conservation of Nature (IUCN) Red List demonstrates that these valuable genetic resources are under high anthropogenic threat. The dominant threat processes are land use change for agriculture and farming, invasive and other problematic species (e.g. pests, genetically modified organisms) and use of biological resources, including overcollection and logging. The most significant drivers of extinction relate to smallholder agriculture—given its high incidence and ongoing shifts from traditional agriculture to modern practices (e.g. use of herbicides)—smallholder ranching and housing and urban development and introduced genetic material. There is an urgent need to increase knowledge and research around different aspects of CWR. Policies that support in situ and ex situ conservation of CWR and promote sustainable agriculture are pivotal to secure these resources for the benefit of current and future generations

Destrucción de instituciones comunitarias y deterioro de los bosques en la Reserva de la Biosfera Mariposa Monarca, Michoacán, México

Analiza las causas que han influido en las condiciones de los bosques comunitarios en dos comunidades del estado de Michoacán. Desde la perspectiva de la acción colectiva, da cuenta de las formas en que, a lo largo de la segunda mitad del siglo XX, distintas políticas públicas afectaron las instituciones comunitarias y las estruc-turas de incentivos para el manejo de los bosques comunes. ¿Cómo han influido esas instituciones e incentivos en las prácticas de uso de los recursos? En un caso, ello ha ocasionado condiciones de deterioro; en el otro, ha favorecido la conservación de las masas forestales

Demography of Bursera glabrifolia, a tropical tree used for folk woodcrafting in southern Mexico: an evaluation of its management plan

Tropical dry forest in Mesoamerica has long been disturbed by the extraction of different forest products by local inhabitants. Bursera glabrifolia (white “copalillo”) is a dry tropical forest tree extensively used in several communities of the State of Oaxaca, Mexico, for the elaboration of folk-art woodcarvings called “alebrijes”. Historically, the extraction of B. glabrifolia had not been regulated; however, in October 2002, the first management plan for this species was implemented in San Juan Bautista Jayacatlán, based on abundance, distribution and dasonomic data. However, no demographic information is available on which to base a sounder management plan that would guarantee the ecological sustainability of this extractive activity. Thus, we studied the population dynamics of this species over a 2-year period in Jayacatlán, where no tree extraction had taken place since 1998. We used stem expansion rates and observations on survival and fecundity to build size-based population projection matrices. The projected population growth rate values (?) were 1.14 and 1.04 for the 2001–2002 and the 2002–2003 periods, respectively. These values suggest that the B. glabrifolia population at Jayacatlán shows a growing trend. Several harvesting scenarios were simulated to theoretically assess the impact on population dynamics of harvesting whole trees and, in particular, to ascertain whether the extraction regime recommended by the management plan (8 trees/ha/yr) is sustainable. For this purpose, we used an average population matrix where specific entries were modified to simulate different extraction levels. The results suggest that the harvesting regimes established in the management plan for B. glabrifolia are sustainable. However, resource managers should not exceed the amounts recommended by the management plan and should avoid extrapolating our results to other regions of the country where no demographic studies have been carried out. The need for long-term demographic studies and their incorporation in ‘adaptive management plans’ is discussed

La heterogeneidad ambiental en un matorral xerófilo

Se caracterizó la heterogeneidad biótica y abiótica tanto espacial como temporal en dos zonas del matorral xerófilo de la Reserva Ecológica del Pedregal de San Ángel (REPSA). Se identificaron nueve grupos florísticos, los cuales presentaron una distribución diferencial de las especies vegetales presentes en la zona. Cada uno de los grupos fue nombrado respecto a las especies indicadoras, las cuáles fueron consideradas como determinantes de la fisonomía de la comunidad. Utilizando los análisis multivariados (TWINSPAN y CANOCO) se observó que la composición de especies de los grupos se modifi ca espacial y temporalmente. Este estudio sugiere que la variación de algunos factores abióticos como la profundidad del suelo y la pendiente influye de diferente manera en la heterogeneidad del sistema. La heterogeneidad temporal fue evidente al existir una diferente composición florística en la zona a lo largo de la temporada de lluvias y la temporada de secas

Seed rain after a fire in a xerophytic shrubland Lluvia de semillas después de un incendio en un matorral xerófilo

Fire causes a reduction of plant cover due to the death of several structures, especially of those that are not isolated from high temperatures; such as seeds and fruits. After a disturbance the availability of diaspores is crucial for the recovery of the community. This work studied the composition and abundance of the seed rain in the xerophytic shrubland of the Pedregal de San Ángel Ecological Reserve, located at the Universidad Nacional Autónoma de México campus in Mexico City, which was affected by a surface fire. In order to understand the role of diaspores in the natural regeneration of a burned site, seed traps were placed on 2 sites, one affected by the fire and the other in an unburned location. During 1 year the dispersed seeds and fruits were collected and identified. Results showed that species richness, life forms, and dispersal syndromes were different between sites. The highest abundance and richness values were observed in the burned site. This work offers basic data on the availability of species as diaspores, information which is useful for potential restoration strategies especially in those areas under constant anthropogenic disturbances.<br>El fuego causa la reducción de la cobertura vegetal debido a la muerte de diversas estructuras, especialmente de aquellas que no están aisladas de las altas temperaturas, tal es el caso de semillas y frutos. Dado que estas diásporas permiten la recuperación de la vegetación, resulta crucial entender su composición y abundancia sobre todo después de un disturbio. Este trabajo estudió la composición y abundancia de la lluvia de semillas en el matorral xerófilo Reserva ecológica del Pedregal de San Ángel, localizado en el campus de la Universidad Nacional Autónoma de México en la ciudad de México, el cual fue afectado por un incendio superficial. Con el fin de entender el papel de las diásporas en la regeneración natural se colocaron trampas de semillas en dos sitios, uno quemado y uno no quemado. Durante un año las diásporas fueron colectadas e identificadas. Los resultados mostraron que la riqueza de especies, las formas de vida y los síndromes de dispersión fueron diferentes entre sitios. Los mayores valores de abundancia y de riqueza de diásporas fueron observados en el sitio quemado. Este trabajo ofrece información básica acerca de la disponibilidad de las especies en forma de diásporas, misma que es estratégica en la restauración futura de áreas sujetas a constantes disturbios antropogénicos