Search Results (4)

Genetic conservation is key to maintaining forests for the future; however, these face several threats. Mexico is an example of the degradation of forest genetic resources during the past three decades due to its deforestation rates. This country is considered a center of pine diversity but its genetic conservation efforts are not enough. To define genetic conservation units (GCUs) and propose measures for the conservation and sustainable use of 18 Mexican pine species, we analyzed the distribution of the species at the national level and in germplasm transfer zones, and evaluated the species with a set of minimum requirements for conservation and indicators from the EUFORGEN program. We determined that 13 to 15 genetic zones harbored the target species, in which Pinus teocote, Pinus cembroides, Pinus devoniana, Pinus maximinoi, Pinus douglasiana, and Pinus leiophylla were the most widely distributed. We defined 173 areas for establishing GCUs for the total of the species studied; 50% of them were selected from areas with genetic information, 5% were selected from seed stands, and 45% from natural forests. We detected that most of the forest reproductive material used is collected from seed stands, and the use of seeds from breeding trials is scarce. Full article

It is critical to understand the ecological processes of forest dynamics by identifying past forest disturbances to take appropriate management actions. Tree-rings are commonly used for this purpose due to their reliability and accuracy. Here, we used a network of ring-width data distributed along a broad ecological gradient for the spatiotemporal identification of forest disturbances in 15 species of 13 sites of young Mexican conifers. We found different spatial and temporal patterns in the occurrence of forest disturbance. The species with the highest disturbance rates were Pinus patula (Ppa; El Jacalón), Pinus montezumae (Pmo; La Cueva), Pinus hartwegii (Phc; Cerro El Moro), and Pinus teocote (Pts; Rancho Joyas del Durazno) of the Gulf of Mexico, and Pinus ayacahuite (Pay; Corral de los Borregos) of the Mexico Center. The highest number of disturbances was found in 1953, 1956, 1976, and 1980; however, we noted that the number of disturbances tended to increase from 1975 to 1990 and particularly from 2000 onwards. The species close to the Gulf of Mexico presented a higher frequency and severity of disturbances than those located close to the Pacific Ocean. Thus, our results demonstrate a spatiotemporal pattern of disturbance events, which deserves further analysis, including regarding the drivers of disturbance. This knowledge is crucial for a better understanding of the dynamics of contemporary species. Full article

Understanding hybridization is important for practical reasons, as the presence of hybrid trees in seed stands can influence the success of natural regeneration and reforestation. Hybridization creates new gene combinations, which can promote or enhance adaptation to new or changing environments. In the present research, we aimed, for the first time, to evaluate and compare the growth and survival of 541 putative hybrid seedlings and 455 seedlings of the pure parental trees of Pinus arizonica, P. durangensis, P. engelmannii, P. leiophylla, and P. teocote, in two reciprocal trials of duration 27 months in the Sierra Madre Occidental (SMO), Durango, Mexico. We also examined the possible correlation between needle stomatal density and seedling growth and survival. The overall analysis of the data showed that the mean height to the apical bud was significantly higher (p = 0.01) in the hybrids than in the pure trees. Considering both trials, the survival rate of P. arizonica (p = 0.002) and P. durangensis (p = 0.01) hybrids was significantly higher than that of the pure trees. The growth parameters were significantly correlated with the mean stomatal density (p < 0.01). Stomatal density and survival at the seed stand level were significantly and positively correlated in the hybrids, but not in the pure trees. In summary, Pinus hybrids generally exhibited the same ability as the pure species (or sometimes a greater ability) to withstand weather conditions, survive, and grow effectively in both growth trials. The systematic use of natural pine hybrids in Mexico could therefore be considered a possible option for sustainable management and as a component of adaptive silviculture. Full article

Species distribution models have become some of the most important tools for the assessment of the impact of climatic change, and human activity, and for the detection of failure in silvicultural or conservation management plans. In this study, we modeled the potential distribution of 13 tree species of temperate forests distributed in the Mexican state Durango in the Sierra Madre Occidental, for three periods of time. Models were constructed for each period of time using 19 climate variables from the MaxEnt (Maximum Entropy algorithm) modelling algorithm. Those constructed for the future used a severe climate change scenario. When comparing the potential areas of the periods, some species such as Pinus durangensis (Martínez), Pinus teocote (Schiede ex Schltdl. & Cham.) and Quercus crassifolia (Bonpl.) showed no drastic changes. Rather, the models projected a slight reduction, displacement or fragmentation in the potential area of Pinus arizonica (Engelm.), P. cembroides (Zucc), P. engelmanni (Carr), P. leiophylla (Schl), Quercus arizonica (Sarg), Q. magnolifolia (Née) and Q. sideroxila (Humb. & Bonpl.) in the future period. Thus, establishing conservation and reforestation strategies in the medium and long term could guarantee a wide distribution of these species in the future. Full article