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In land plants, heteroblasty broadly refers to a drastic change in morphology during growth through ontogeny. Juniperus flaccida and Pinus cembroides are conifers of independent lineages known to exhibit leaf heteroblasty between the juvenile and adult life stage of development. Juvenile leaves of P. cembroides develop spirally on the main stem and appear decurrent, flattened, and needle‐like; whereas adult photosynthetic leaves are triangular or semi‐circular needle‐like, and grow in whorls on secondary or tertiary compact dwarf shoots. By comparison, J. flaccida juvenile leaves are decurrent and needle‐like, and adult leaves are compact, short, and scale‐like. Comparative analyses were performed to evaluate differences in anatomy and gene expression patterns between developmental phases in both species. RNA from 12 samples was sequenced and analyzed with available software. They were assembled de novo from the RNA‐Seq reads. Following assembly, 63,741 high‐quality transcripts were functionally annotated in P. cembroides and 69,448 in J. flaccida. Evaluation of the orthologous groups yielded 4140 shared gene families among the four references (adult and juvenile from each species). Activities related to cell division and development were more abundant in juveniles than adults in P. cembroides, and more abundant in adults than juveniles in J. flaccida. Overall, there were 509 up‐regulated and 81 down‐regulated genes in the juvenile condition of P. cembroides and 14 up‐regulated and 22 down‐regulated genes in J. flaccida. Gene interaction network analysis showed evidence of co‐expression and co‐localization of up‐regulated genes involved in cell wall and cuticle formation, development, and phenylpropanoid pathway, in juvenile P. cembroides leaves. Whereas in J. flaccida, differential expression and gene interaction patterns were detected in genes involved in photosynthesis and chloroplast biogenesis. Although J. flaccida and P. cembroides both exhibit leaf heteroblastic development, little overlap was detected, and unique genes and pathways were highlighted in this study. [ABSTRACT FROM AUTHOR]

Pinus cembroides and P. orizabensis produce edible seeds, which are sold at different prices depending on the color of their seed coat or testa. Germinative quality of the seeds was evaluated considering their color and three provenances per species: Colón and Cadereyta, Querétaro, and Santiago de Anaya, Hidalgo, for P. cembroides; Tepeyahualco, Puebla, and El Carmen and Altzayanca, Tlaxcala, for P. orizabensis. The combination of the factors color, provenance and species allowed us to form 18 lots. Testa thickness and germination were determined with four replications of 25 seeds and 15 replications for the imbibition test per lot. Analyses of variance were performed to test differences between species and among provenances and seed coat colors. Testa thickness, germinative capacity, peak value, and rates of imbibition and germination were different between species. The P. cembroides testa was 0.1 mm thicker and germination capacity was 4% higher than P. orizabensis. The peak value was higher and germination faster in P. cembroides (12.7 vs. 13.4 d to reach 50% germination). Provenance was significant for germinative capacity, days to 50% germination, peak value, and days to reach peak value. P. cembroides from Cadereyta had the highest germination (95%); seed from Colón germinated faster. Lower vigor and germination (4.4 and 87.5%) were found in seeds from Santiago de Anaya. The P. orizabensis seeds from El Carmen had higher germination (87.1%) and those from Tepeyahualco and Altzayanca higher germination rate. Brown seeds of both species had thicker testa and higher germination capacity. Black P. cembroides seeds have thinner testa and germinated at a faster rate than those with brown seed coat. Brown P. orizabensis seeds were more vigorous. [ABSTRACT FROM AUTHOR]

In this study, we examined the spatial genetic structure (SGS) in extensively managed, but naturally regenerated forest stands of Pinus cembroides Zucc., Pinus discolor Bailey et Hawksworth, Pinus durangensis Martínez, and Pinus teocote Schiede ex Schltdl. & Cham. at local (within the stands) and large (among the stands) scales using amplified fragment length polymorphisms (AFLP), with respect to conservation and sustainable management of genetic resources of these species. Because these four pine species grow in different landscape structures, we expected to find differences in their SGS, although all of them are widely spread, wind pollinated, and often occur at high population densities. At the local scale, there was no evidence of significant SGS in the four species under study (except in 1 out of 18 seed stands), suggesting that the genetic variants of these species are almost always randomly distributed in space, probably due to high wind pollination and seed dispersal. At a larger scale, the significant SGS found may be the result of isolation by distance among populations. We recommend ( i) establishing a tight network of seed stands, with a maximum distance of 3-11 km between seed stands, to prevent greater loss of local genetic structure, and ( ii) using these seeds to establish reforestations within a maximal radius of 3-5 km from seed provenances. [ABSTRACT FROM AUTHOR]

Ecological restoration is considered an important tool to reverse the degradation conditions that diverse ecosystems present worldwide, where its purpose is to recover the ecosystem structure and processes. Reforestation is a widely used strategy for restoration, which generally considers only the survival and growth as part of its monitoring. Therefore, the objective of this study was evaluating the effect of Pinus greggii introduction in the structure, biomass and the understory species diversity. Three reforested sites were selected -of 5, 12 and 14 years old-, a reference site (dominated by Pinus cembroides) and a degraded site (dominated by grasses). We established eight circular 400 m², 100 m² and 1 m² plots (nested) to measure diameter, height of tree canopy, shrubs and herbaceous richness and diversity in the understory. Allometric equations were used to calculate aerial biomass. Alpha and beta diversity of the understory was determined. The highest biomass accumulation was found in the reference site (25.27 Mg ha-1), followed by the older reforestation (R14) with 14.16 Mg ha-1. These had higher species richness and diversity likewise. The Jaccard index showed larger similarity between the degraded site and the five year-old reforestation (61 %). It was found that R14 achieved accumulation of biomass, species richness and diversity similar to those from the reference site. [ABSTRACT FROM AUTHOR]

The present study aims to determine the damage intensity of the pinyon pitch nodule moth, Retinia arizonensis and their possible relationship to some structural parameters: stem diameter, height and coverage, as well as the natural regeneration of Pinus cembroides and P. nelsonii. For their evaluation, sites with 2,500 m² of each species were located. A total of 136 individuals of P. cembroides were recorded, with an average damage of 10.5% (±8.1 SD) in the terminal buds. In P. nelsonii, a total of 47 individuals were found, 46 exhibited damage from R. arizonensis, averaging 4.8% (±4.5 SD), twice less than P. cembroides. We used the Kruskal-Wallis (H-Chi²) to assess the damage of R. arizonensis between species, marked significant difference (p < 0.001) was observed. Relating to the structure, P. cembroides showed the following mean values: stem diameter = 10.7 cm (±8.0 SD), height = 2.9 m (±1.0 SD) and coverage = 3.0 m² (±1.8 SD). With respect to P. nelsonii, these were: stem diameter = 10.7 cm (±4.3), height = 3.6 m (±0.8) and coverage m² = 4.2 (±1.8), these variables showed wide statistical differences (p < 0.001). When measuring the association of R. arizonensis damage, with the structural variables, P. cembroides showed a positive marginal correlation with the variables height, diameter and covering with r² = 0.12, 0.16 and 0.18, respectively (p < 0.001). However, P. nelsonii expressed non-significant correlations among R. arizonensis damage with the structural parameters. The combined influence of the three structural variables (multiple correlation r²) of R. arizonensis damage, was mostly explained in P. cembroides with r² value of 0.19 highly significant (p < 0.001). In relation to P. nelsonii, the structural variables influenced on damage percentage of R. arizonensis were not significant (p = 0.128). Natural regeneration showed percentage participation (relative to adult trees) of 20.6% for P. cembroides and 42.5% for P. nelsonii with mean height of 13.9 cm (±12.6) and 28.4 cm (±20.0) in P. cembroides and P. nelsonii, respectively. [ABSTRACT FROM AUTHOR]

• Trees growing on shallow rocky soils must have exceptional adaptations when underlying weathered bedrock has no deep fractures for water storage. Under semiarid conditions, hydrology of shallow soils is expected to decouple from plant hydrology, as soils dry out as a result of rapid evaporation and competition for water increases between coexisting tree species. • Gas exchange and plant-water relations were monitored for 15 months for Pinus cembroides and Quercus potosina tree species in a tropical semiarid forest growing on c. 20-cm-deep soils over impermeable volcanic bedrock. • Soil and leaf water potential maintained a relatively constant offset throughout the year in spite of high intra-annual fluctuations reaching up to 5 MPa. Thus, hydrology of shallow soils did not decouple from hydrology of trees even in the driest period. A combination of redistribution mechanisms of water stored in weathered bedrock and hypodermic flow accessible to oak provided the source of water supply to shallow soils, where most of the actively growing roots occurred. • This study demonstrates a unique geoecohydrological mechanism that maintains a tightly coupled hydrology between shallow rocky soils and trees, as well as species coexistence in this mixed forest, where oak facilitates water access to pine. [ABSTRACT FROM AUTHOR]

Mortality in six plant species was examined in the vegetation of a mountain region in Northeastern Mexico and hypotheses of survival pathways within populations in the ecosystem were tested. Significant differences in the general mortality pattern were found among species indicating species-specific responses to stress gradients. Average mortality differed among species: Yucca carnerosana, 33.8%; Pinus cembroides, 29.9%; Larrea tridentata, 25.9%; Hechtia podantha, 13.7%; Agave lechuguilla, 13.0%; and Thelocactus santaclarensis, 9.0%. Within populations, mortality increased with water stress and survivorship increased with less stressful environments. Results from this study may be useful for the development of a management plan to support the conservation and sustainable use of forest vegetation in this mountain community. [ABSTRACT FROM AUTHOR]

Water quality is a relevant factor for production of forest species, but it is not always taken into account in nurseries in Mexico. One of the parameters of water quality is its acidity. The objective of this work was to study the response in morphology and concentration of ions and cations in leaf tissue of Pinus cembroides Zucc., to different water pH and concentrations of compounds in fertigation solutions. Plants were cultivated in a nursery in 170 cm3 containers with a substrate made of peat moss (40 %), vermiculite (30 %) and agrolite (30 %). The experimental design was completely randomized blocks with two factors and two levels: 1) pH of irrigation water (8 and 5.5); 2) fertilization (ppm): establishment (50-123-73 of N, P, K for both levels), growth (100-22-83 and 150-33-125) and finalization (15- 41-109 and 30-82-218); these levels of fertilization were denominated low and high. The effect of factors and their interaction was determined with an ANOVA (p⩽0.10). The morphological variables and quality indexes evaluated were height, diameter, shoot dry weight, root dry weight, Dickson quality index, shoot/root ratio, lignification index, slenderness index and leaf nutrient concentration. There was no response in terms of morphological variables or indexes. There was, however, a response in leaf nutrient concentration. The highest leaf concentration of K (p⩽0.001) was obtained with high fertilization at both levels of pH, and the highest concentration of Mn with higher fertilization without adjusting pH (8.0). The highest concentrations of Ca (p⩽0.092), Mg (p⩽0.074), and Cu (p⩽0.093) occurred with high fertilization and pH=5.5, and that of Zn (p⩽0.001) was with low fertilization and adjusted pH. There were interactions between fertilization and water pH for K (p⩽0.005), Ca (p⩽0.1) and Zn (p⩽0.039). The highest nutrient concentrations were obtained with water pH=5.5 and high fertilization. [ABSTRACT FROM AUTHOR]

La calidad del agua es un factor relevante para la producción de especies forestales, pero no siempre se toma en cuenta en viveros de México. Uno de los parámetros de calidad de agua es su acidez. El objetivo de esta investigación fue estudiar la respuesta en la morfología y en la concentración de iones y cationes en el tejido foliar de Pinus cembroides Zucc., a diferentes niveles de pH de agua y concentraciones de compuestos en las soluciones de ferti-irrigación. Las plantas fueron cultivadas en vivero, en contenedores de 170 cm3, con sustrato a base de turba de musgo (40 %), vermiculita (30 %) y agrolita (30 %). El diseño experimental fue en bloques completamente al azar, con dos factores y dos niveles por factor: 1) pH del agua de riego (8 y 5.5); 2) fertilización (ppm): establecimiento (50-123-73 de N, P, K para ambos niveles), crecimiento (100-22-83 y 150-33-125), y finalizador (15-41-109 y 30-82-218); estos niveles de fertilización se denominaron bajo y alto. El efecto de factores y su interacción fue determinado con un ANDEVA (p⩽0.10). Las variables morfológicas e índices de calidad evaluados fueron: altura, diámetro, peso seco aéreo, peso seco de raíz, índice de calidad de Dickson (ICD), relación parte aérea/raíz, índice de lignificación, índice de esbeltez y concentración nutrimental foliar. No hubo respuesta en variables morfológicas ni en índices, pero sí en concentración nutrimental foliar. La mayor concentración foliar de K (p⩽0.001) fue con la fertilización alta en ambos niveles de pH, y la de Mn con fertilización alta y sin ajuste de pH (8.0). Las mayores concentraciones de Ca (p⩽0.092), Mg (p⩽0.074) y Cu (p⩽0.093) ocurrieron con fertilización alta y pH=5.5, y la de Zn (p⩽0.001) fue con fertilización baja y pH ajustado. Hubo interacciones entre fertilización y pH del agua para K (p⩽0.005), Ca (p⩽0.1) y Zn (p⩽0.039). Las mayores concentraciones nutrimentales fueron para agua con pH=5.5 y la fertilización alta. [ABSTRACT FROM AUTHOR]

Highlights: [•] We propose that an integral approach is needed to analyze complex taxonomic groups. [•] Genetic, morphological and geographical data define species boundaries and phylogenetic relationships in pinyon pines. [•] We suggest a reevaluation of the conservation status of Subsection Cembroides. [•] The combined approach should be considered in other groups with similar complexity. [ABSTRACT FROM AUTHOR]

Litterfall production is a measurement of net primary productivity, which is also related to carbon stores in the soil. The objective of this investigation was to quantify during one year the litterfall of a population of Pinus cembroides Zucc. (685 trees ha-1 of 60 years) and one of P. halepensis Mill. (3760 trees ha-1 of 20 years), located in the same site in the Sierra of Arteaga, Coahuila, México, and correlate it with the environmental factors. The collections were made monthly from March 2010 to February 2011. The Kruskal-Wallis non-parametric test (95 %) indicated that litterfall was statistically higher (p£0.0001) in P. halepensis (27.21±22.11 g m-2 month-1) than in P. cembroides (8.19±10.75 g m-2 month-1), represented 2697.41 and 922.75 kg ha-1 year-1 and varied in time; tree density was a determining factor of these differences. In agreement with other studies, needlefall of P. cembroides presented low correlation with environmental factors, in contrast with P. halepensis, which is susceptible to changes of precipitation and temperature. [ABSTRACT FROM AUTHOR]

To test the hypothesis that Mexican pinyons (Pinus cembroides) and Johannis pines (P. johannis) grow under different environmental conditions, the flora associated with both species was sampled along two 20-m perpendicular transects at 40 sites. Patterns were analyzed with the two-way-indicator-species program, which yielded six groups with Mexican pinyons dominating xeric sites and Johannis pines dominating mesic sites. Other groups of species corresponded to transition from mesic to xeric sites. We used canonical-correspondence analysis to explore the effect of slope and aspect on species and indirectly related them to an underlying moisture gradient. The first ordination axis indicated that aspect explained 59% of the variation, and the second axis, representing slope, explained 41%. [ABSTRACT FROM AUTHOR]

It is well known that inherent characteristics of forest species constitute the main control of litter decomposition. In mixed forest, chemical interactions occurring through precipitation turn mechanisms of litter decomposition very uncertain and difficult to predict. Early-stage leaf litter decomposition of Quercus potosina and Pinus cembroides and their controls were examined based on Ostrofsky's decomposition mechanisms. From June 2007 to May 2008, litterbags with pure and mixed leaf-litter of Q. potosina and P. cembroides were incubated in situ in monospecific and mixed tree stands, respectively. Sampling was carried out 3, 6, 9, and 12 months after incubation. After 12 months, two phases of decomposition of pure and mixed litter were identified; an early phase with a greater rate of mass loss of the labile litter fraction ( k ; soluble compounds) and a later phase with a lower rate of mass loss of the recalcitrant litter fraction ( k; lignin). The labile fraction lost was observed at three and 6 months of incubation, which coincided with the months of highest rainfall likely triggering a rapid release of soluble carbon compounds from leaf litter. Results also indicate that leaf-litter from Q. potosina had higher concentration of soluble compounds and lower lignin concentration than leaf litter from P. cembroides. Observed facilitative and inhibitory mechanisms for mass loss in Q. potosina and P. cembroides were controlled by interaction between physico-chemical litter characteristics and rainfall. [ABSTRACT FROM AUTHOR]

The Sierra Zapaliname (SZA) is the most important source of water for Saltillo and neighboring settlements. Population increase is putting pressure on limited water sources, therefore it is necessary to have a better understanding of historical hydroclimate variability for planning the proper use of limited water resources. Tree-ring series were developed for the lower, mid, and upper sections along an altitudinal gradient in SZA. The chronology length was 412 years (1595-2006), 306 years (1700-2005), and 603 years (1400-2002), for the lower, mid, and higher elevation, respectively. The lower elevation tree-ring chronology had higher climatic sensitivity to dry periods as compared to those of the mid and upper elevation sections. Intense and extended droughts were detected along the altitudinal gradient in the 1440s to 1450s, 1530s, 1590s, 1640s, 1660s, 1690s, 1710s, 1740s, 1750s, 1760s, 1790s, 1860s, 1890s, 1920s, 1950s, and 2000s, and produced local and regional food shortage and epidemic outbreaks. Severe droughts were detected at frequencies of 100 years followed by mid intensive droughts at 50-year periods. The climatic influence of ENSO in determining hydro-climatic behavior of SZA has not been significant and other circulatory patterns (cold fronts, hurricanes, tropical storms) could better explain the historical climate variability that has characterized this mountain range. [ABSTRACT FROM AUTHOR]

Deals with a study which analyzed allozyme variation to directly assess genetic diversity and genetic structure in maxipinon. Allele frequencies at polymorphic loci scored in each of separate collections of maxipinon; Allele frequencies and fixation indices for polymorphic loci in maxipinon; Multilocus outcrossing rate based on polymorphic loci in families of maxipinon.

The development of winter apical buds and the initiation of female cones of Pinus cembroides in the Southern Sierras of the State of San Luis Potosí, were studied during 1985 and 1986. The initiation of cone primordia was delayed in 1985 approximately one month in comparison with 1986. This phenomenon coincided with differences of precipitation and temperature in relation to the 11 years average of the nearest climatological station (El Peaje). The course of precipitation and temperature for 1986 resembled the average and hence can be considered as more representative for the area; in that year the initiation of cone primordia ranged from middle August to late September (or early October). Annual fluctuation of precipitation and temperature may cause changes in the period of differentiation of cone primordia. [ABSTRACT FROM AUTHOR]