1Autor para la correspondencia: jlleon04@cibnor.mx Resumen: Los objetivos de este trabajo fueron integrar el listado florístico de la selva baja caducifolia en la península de Baja California y delimitar su presencia. Esta comunidad vegetal ocupa una superficie de 3,325 km 2 en el extremo sur peninsular, que se ha propuesto como la versión más seca de las selvas bajas en México. Después de décadas de esfuerzos, actualmente se considera que su composición florística está adecuadamente representada en el herbario del Centro de Investigaciones Biológicas del Noroeste. El listado cuenta con 645 taxa de plantas superiores y de ellos 37 son endémicos. Con base en muestreos de campo, se discute la composición florística de los dominantes ecológicos de esta comunidad. Sobresale Lysiloma microphyllum como especie indicadora de este tipo de vegetación. En el análisis de las formas de crecimiento, se resalta el de las trepadoras, cuyo número es similar al registrado para el desierto Sonorense y comunidades contiguas, pero notablemente inferior al de otras selvas bajas caducifolias del sur de México. Palabras clave: bosque neotropical, endemismos, Lysiloma microphyllum, trepadoras. Abstract:The objective of this research was to prepare a floristic list of the tropical dry forest in Baja California Peninsula and to delimit its coverage. This forest covers 3,325 km 2 in the mountainous southernmost part of the peninsula; this community is the driest version of its type in Mexico. After decades of fieldwork, the representation of the flora in the herbarium of the Centro de Investigaciones Biologicas is almost complete. There are 645 taxa of vascular plants, of which 37 are endemics to this area. The authors discuss the floristic composition of the ecologically dominant plants based on field surveys. Lysiloma microphyllum is the most important species in this vegetation community. Using growth form analysis, we found that climbers have a proportional frequency similar to that of the Sonoran Desert flora and neighboring communities, but are significantly less than other dry tropical forests in southern Mexico. Key words: climbers, endemicity, Lysiloma microphyllum, neotropical forest.FLORÍSTICA Y TAXONOMÍA D e acuerdo con Miranda y Hernández-X. (1963), la vegetación tropical seca en México se conceptualiza bajo la denominación selva baja caducifolia (SBC), mientras que Rzedowski (1978) la denomina bosque tropical caducifolio. El concepto engloba a la vegetación de franca afinidad tropical cuya principal característica consiste en que la mayor parte de los árboles y arbustos pierden sus hojas al menos durante seis meses debido a la prevalencia de un período sin lluvias.En el contexto mundial la SBC mexicana forma parte del concepto del seasonally tropical dry forest que se extiende discontinuamente a través de la vegetación subtropical en América (Gentry, 1982;Pennington et al., 2009;Dirzo et al., 2011). Según Holdridge et al. (1971 este tipo de vegetación se distribuye en las regiones subtropicales del planeta, en un nivel altit...

We estimated the mule deer Odocoileus hemionus peninsulae (Lydekker 1898) population in six locations of an oak-pine forest in the Sierra de La Laguna in the Cape Region of Baja California Sur, Mexico, during 7 consecutive years (1987 to 1993 ). The most important habitat variables for deer (plant biomass, cover, and water) were measured over five wet and dry seasons at the same locations. The population estimation (based on pellet-group counts) resulted in an average density of 19 ± 5 deer/km 2 . The deer habitat in the area is typified by different association proportions of Black Oak Quercus devia-Pinyon Pine Pinus lagunae-Oak Quercus tuberculata-Madrone Arbutus peninsularis.There is a marked seasonality in the vegetation. In general, the habitat transects revealed ample cover and plant biomass, shrubs being the dominant growth form and that most frequently consumed by the deer. The deer population is less than the habitat's carrying capacity in the wet and dry seasons. None of the habitat variables measured are a limiting factor, though deer were found to prefer sites with greater amounts of cover and biomass of shrubs. All sites surveyed contain available water and are in rugged terrain.

Stenocereus gummosus ("pitaya agria", Cactaceae) is a wild native species of the Baja CaliforniaPeninsula, Mexico. The fruit of these plants is harvested by ranchers for public consumption. There has been no attempt to cultivate this species or to enhance fruit production by selecting highly productive lines with desirable characteristics. Nevertheless, it is relatively easy to propagate asexually. Seed propagation is not practical in spite of its regular flower, fruit, and viable seed generation.Here, the "pitaya agria" was studied over 4 years (1988)(1989)(1990)(1991) to generate basic information that may be useful for its induction to cultivation. A sample of plants was monitored during phenological events of budding, flowering, fruiting, and abortion. Among the results, we found that a third of the original buds developed into fruit, and the first 40 cm of the branches yielded more buds where the conversion into fruit was higher than in the rest of the branch. A statistical analysis revealed slight differences in the phenological events, despite dissimilar rainfall over the four years. In view of its successful asexual propagation, this species can be considered commercially promising.

No abstract