Fuego, mortalidad y rebrotación en especies forestales de la Sierra Norte de Puebla

Los incendios forestales están aumentando en el planeta debido al efecto invernadero, por lo que es necesario comprender mejor sus efectos, para lograr un adecuado manejo del fuego. El objetivo de este trabajo fue evaluar y modelar las probabilidades de mortalidad (Pm) y rebrotación (Pr) en Pinus montezumae, Pinus teocote, P. patula, Quercus spp. (Q. crassifolia, Q. rugosa, Q. crassipes), Arbutus xalapensis y Alnus acuminata nueve meses después de un incendio en el ejido Michac, municipio de Chignahuapan, Puebla. Se usaron modelos logísticos y las estimaciones se obtuvieron con el programa SAS. Se logró obtener modelos robustos para la Pm en una especie (dos modelos) y la Pr en tres especies (siete modelos). La Pm fue una función inversa de la altura y el diámetro normal en P. montezumae. Para Pr, se encontró una relación inversa con altura y diámetro normal en P. montezumae, Q. spp. y A. xalapensis, así como una relación directa con el porcentaje de copa afectada en P. montezumae (todos los modelos con p ≤ 0.05 para las variables, límites de confianza sin incluir 1, concordancia ≥ 40% y p de la prueba de bondad de ajuste > 0.05). A pesar de la severidad del fuego, las especies muestran adaptaciones, como la rebrotación, que indican supervivencia. Este tipo de información es de utilidad para estimar mortalidad arbórea por incendios, en quemas prescritas, la elección de sitios para manejo de combustibles y valorar la conveniencia de realizar actividades de reforestación y restauración.

A brief overview of acute poisoning in sheep

Acute poisoning in sheep can occur following ingestion of toxic plants, including plants that they may eat normally such as ivy (Hedera spp.) and plants they avoid unless other forage is unavailable. Poisoning with plants containing grayanotoxins (Pieris and Rhododendron spp.) is very common in sheep, particularly when the weather is poor and they are hungry. Oak (Quercus spp.) poisoning is also relatively common in sheep, particular in years with a heavy acorn crop. Numerous plants contain cardiac glycosides and are a potential risk to sheep. Sudden death is frequently the first signs of plant toxicosis in livestock. Bites from adders (Vipera berus berus) may also occur in sheep but are likely to be underreported as the actual biting event is not witnessed. Envenomation may result in swelling and haematological, renal, hepatic and cardiac effects. Overdosage of drugs with a narrow therapeutic index may also be a risk. One such example is closantel which can result in blindness. Management of acute poisoning in sheep is supportive including removal from exposure, and providing analgesia, rehydration and potentially a rumenotomy for plant exposure in valuable animals.

Fuel Modelling Characterisation Using Low-Density LiDAR in the Mediterranean: An Application to a Natural Protected Area

Fuel structure and characteristics are important to better understand and predict wildfire behaviour. The aim of the present study was to develop a methodology for characterising fuel models using low-density and free LiDAR data that facilitate the work of managers of protected territories. Field inventories were carried out in order to understand the characteristics of the stand and the variables that fuel models must include. This information, together with the use of the intensity and structure provided by LiDAR, was used to perform statistical analyses. The linear regressions obtained to characterise the stand of the mixed Quercus spp.–Pinus ssp.-dominated stand had an R2 value ranging from 0.4393 to 0.66. While working with low-density LiDAR data (which has more difficulties crossing the canopy), in addition to the obtained results, we performed the statistical analysis of the dominant stand to obtain models with R2 values ranging from 0.8201 to 0.8677. The results of this research show that low-density LiDAR data are significant; however, in mixed stands, it is necessary to only use the dominant stratum because other components generate noise, which reduces the predictive capacity of the models. Additionally, by using the decision tree developed in combination, it is possible to update the mapping of fuel models in inaccessible areas, thereby significantly reducing costs.

Oak leaf (Quercus spp.) intoxication in a sheep

A twenty-year-old ewe presented with acute lateral decubitus, tremor and dyspnea, followed by death. Post-mortem examination revealed a large amount of oak leaves in the rumen, reticulum and omasum. The duodenum had a focal hemorrhagic content and multifocal hemorrhages were present in several organs. Histopathological examination of the kidneys showed characteristic lesions of oak intoxication, such as intratubular hemorrhage, tubular degeneration and necrosis. This case report illustrates the importance to include oak intoxication in the differential diagnosis of acute death in sheep and the value of post-mortem and histopathological examination.