DIVERSITY OF SHRUB SPECIES IN A SEMIARID AREA OF CENTRAL MEXICO
DIVERSIDAD DE ESPECIES ARBUSTIVAS EN UNA ZONA SEMIÁRIDA DEL CENTRO DE MÉXICO
/ pages 323-335
The alpha diversity (true diversity) and beta diversity (turnover and nestedness) of shrub species were evaluated in the semiarid area of Hidalgo, Mexico. The importance value index of species was related to soil variables and climatic factors. We found 46 species from 21 families. Asteraceae and Fabaceae were the most important. The greatest number of effective species recorded was 7.8 and the smaller was 1.6. Beta diversity was high (0.9), mainly due to the turnover component (0.87) and to a lesser extent due to nestedness (0.38). Precipitation, nitrogen, pH and percentage of sand were the most important variables to explain the species distribution. These results agree with those reported in other semiarid areas. High regional diversity is due to a high species turnover generated by environmental heterogeneity that is displayed as a mosaic of conditions, both climatic and soil characteristics.
DISAGGREGATED DYNAMIC GROWTH MODELS FOR ESTIMATING VOLUME AND BIOMASS IN EVEN‑AGED STANDS
MODELOS DINÁMICOS DE CRECIMIENTO PARA RODALES REGULARES Y SU DESAGREGACIÓN PARA LA ESTIMACIÓN DE VOLÚMENES Y BIOMASA
/ pages 337-350
This study presents a methodological process that can be used to develop disaggregated dynamic growth models for estimating total and merchantable volume and aboveground tree biomass (total or by tree component) for single species in even‑aged stands. An example for birch (Betula pubescens Ehrh.) and pedunculate oak (Quercus robur L.) stands in Galicia (northwestern Spain) is used. The stand state at any point in time is defined by three static variables: dominant height, number of trees per hectare and stand basal area. These variables are projected using transition functions in algebraic difference form. A disaggregation system allows estimation of the number of trees and the average height per diameter class from state variables. Finally, output functions that use the estimated diameters and heights are used to estimate volume and biomass.
GERMINATION, INFESTATION, AND VIABILITY IN ACORNS OF Quercus polymorpha (Schltdl. & Cham.) AFTER 1-YEAR STORAGE
GERMINACIÓN, INFESTACIÓN Y VIABILIDAD EN BELLOTAS DE Quercus polymorpha (Schltdl. & Cham.) TRAS UN AÑO DE ALMACENAMIENTO
/ pages 351-362
White oaks have recalcitrant seeds that remain viable for short periods of time, but this information is still conspicuously lacking for Mexican oaks. This is the case of Quercus polymorpha, a drought-tolerant species widely distributed across Sierra Madre Oriental that can be used in forest restoration programs. The acorns used to develop their saplings are collected during the reproductive season and stored by several months before their germination. This study focused in 1) determining how many seeds are lost during storage because of physiological factors linked to their viability, 2) quantifying how many seeds were lost by other factors, and 3) assessing whether cold stratification can stimulate acorn germination. Acorns used in this study were stored during a round year. We found that 70 % of these acorns were parasitized by insects prior to their storage, while an additional 20 % had lost their viability due to physiological factors or fungal infestation. Germination trials were performed by only using potentially viable acorns, which were subjected to three different cold stratification periods (0, 20 and 50 days). This experiment indicated acorns stratified during 50 days display higher germination rates (64.2 %) than those stratified by 20 (44.8 %) and 0 days (16.5 %).
ANALYSIS OF THE REGULATORY FRAMEWORK FOR HARVESTING WILD EDIBLE MUSHROOMS
ANÁLISIS DEL MARCO REGULATORIO EN EL APROVECHAMIENTO DE LOS HONGOS SILVESTRES COMESTIBLES EN MÉXICO
/ pages 363-374
The harvesting of wild edible mushrooms and other non-timber forest products is a food and livelihood strategy for many rural farmers. Despite its social, economic, ecological and cultural importance, it is one of the most isolated and little-known activities in the national primary sector. This is a direct and indirect consequence of the absence of policies, support schemes and development strategies for this activity; therefore, the objective of this work is to expose the need for official statistics on mushroom harvesting and establish the relationship between scientific research, public policies and the current legal framework, in order to determine the current state of this activity and its future outlook. It is observed that the lack of awareness of this activity has resulted in it not being considered for and excluded from the development policies of the government and social and private sectors. Similarly, the lack of information, management and linkage causes a lag in mushroom harvesting and therefore its eventual substitution or replacement by other activities. Despite this, there is definite potential for mushroom harvesting, if properly managed, to provide a real alternative in sustainable forest management in Mexico.
POPULATION STRUCTURE OF Abies religiosa (Kunth) Schltdl. et Cham., IN THE EJIDO EL CONEJO OF THE NATIONAL PARK COFRE DE PEROTE, VERACRUZ, MEXICO
ESTRUCTURA POBLACIONAL DE Abies religiosa (Kunth) Schltdl. et Cham., EN EL EJIDO EL CONEJO DEL PARQUE NACIONAL COFRE DE PEROTE, VERACRUZ, MÉXICO
/ pages 375-385
We studied the structure of fir stands (Abies religiosa) in the ejido El Conejo, residing inside the Cofre de Perote National Park, Veracruz. We assessed density, diameter at breast height, height and coverage of adult trees in 17 plots of 625 m2. The regeneration was measured in 17 plots using sub-quadrants of 312. 50 m2. Trees showed a growing structure “J”; however, trees are suppressed, even when regeneration is adequate, trees requires clear opening for its development. We found a highly fragmented forest area, and permanently threatened due to the growth of the agricultural frontier and extraction of wood for domestic use. Results show evidence that the national park category does not contribute to forest conservation.
EFFECT OF ESTABLISHMENT TECHNIQUE COMBINATIONS ON INITIAL GROWTH OF Grevillea robusta A. Cunn.
EFECTO DE LA COMBINACIÓN DE TÉCNICAS DE
ESTABLECIMIENTO SOBRE EL CRECIMIENTO INICIAL DE Grevillea robusta A. Cunn.
/ pages 387-397
The effect of establishment technique combinations on initial growth of Grevillea robusta was evaluated in the northern area of the province of Corrientes, Argentina. The treatments included the combination of two factors. The first one was applied previous to planting G. robusta and consisted of slash management with two levels: a) slash conservation and, b) slash burning. The second factor consisted of fertilizer application with three levels: a) unfertilized, b) fertilized after plantation establishment and, c) fertilized a year after plantation establishment. The plantation establishment technique combinations changed the initial growth of G. robusta. The best combination was slash burning with fertilization during establishment. With this combination, the plantation achieved a 43.7 % increase in diameter at 36 months of age, which was superior to that obtained with the slash conservation with no fertilization treatment.
ALTITUDINAL VARIATION AMONG SPECIES AND PROVENANCE OF Pinus pseudostrobus, P. devoniana and P. leiophylla. NURSERY TEST
VARIACIÓN ALTITUDINAL ENTRE ESPECIES Y PROCEDENCIAS DE Pinus pseudostrobus, P. devoniana y P. leiophylla. ENSAYO DE VIVERO
/ pages 399-411
Pine-oak forests of San Juan Nuevo, Michoacán are dominated by Pinus pseudostrobus, P. devoniana and P. leiophylla. The patterns of genetic variation of these species are poorly known, particularly those of P. leiophylla, limiting the creation of guidelines for the movement of seeds and seedlings for reforestation and climate change adaptation. Species were collected in four or five provenances along an altitudinal transect (1,650 to 2,500 m) for the establishment of a nursery trial, with the aim of quantifying the genetic variation among and within species. Plant height (three and five months) was significantly different (P < 0.0001) among species. Significant differences among provenances for P. devoniana (P < 0.0001) and P. leiophylla (P = 0.0352) were observed. The species P. devoniana showed a pronounced growth pattern associated with altitude of origin, where the fastest growing plants came from a lower elevation. The populations of P. leiophylla were different only at three months of age, with no statistically significant altitudinal pattern. No significant differences were found among populations of P. pseudostrobus.
RECONSTRUCTION OF WINTER-SPRING PRECIPITATION WITH ANNUAL RINGS OF Pinus douglasiana IN THE SIERRA DE MANANTLÁN BIOSPHERE RESERVE, JALISCO
RECONSTRUCCIÓN DE PRECIPITACIÓN INVIERNO-PRIMAVERA CON ANILLOS ANUALES DE Pinus douglasiana EN LA RESERVA DE LA BIOSFERA SIERRA DE MANANTLÁN, JALISCO
/ pages 413-423
Winter-spring precipitation in the Sierra de Manantlán Biosphere Reserve (SMBR) in Jalisco, Mexico, was reconstructed for a 219-year period (1792-2010) using the annual rings of Pinus douglasiana (Mtz.) as proxy. The drought of the mid-twentieth century (1941-1963, 22 years) was the most severe of the study period. The multivariate El Niño Southern Oscillation index (MEI) (1959-2010) and the tree-ring width index of P. douglasiana showed significant correlation (r= 0.4542; P < 0.05) for the months of January–June, with higher correlation for the months of January (r= 0.4337; P < 0.0001) and March (r= 0.4310; P < 0.0001). ENSO teleconnections in the region vary over time; from January to May, El Niño events are associated with higher than average rainfall, while La Niña events show the opposite.
MORPHOMETRIC MARKERS FOR GENDER IDENTIFICATION IN Zamia furfuracea L. f. (Zamiaceae)
MARCADORES MORFOMÉTRICOS PARA LA IDENTIFICACIÓN DEL SEXO EN Zamia furfuracea L. f. (Zamiaceae)
/ pages 425-434
Zamia furfuracea L. f. is endemic cycad species from Veracruz, Mexico. The species is dioecious cycad, which is endangered. There is no report about the existence of a sexual dimorphism in this species, so it is not possible to perform adequate gender identification in early stages or when there is no strobili. A total of nine morphological variables were evaluated in 31 male and 26 female plants of a natural population of Veracruz to determine differences related to the gender of Z. furfuracea. Number of pairs of leaflets, leaf width, average width of the leaflet and diameter of the petiole were significantly different between genders (P = 0.043, P = 0.032, P = 0.041 and P = 0.002, respectively). These characteristics may form morphometric markers to determine with greater certainty the gender ratio in this species.
FLORISTIC ELEMENTS OF INTEREST FOR CONSERVATION IN WET FORESTS OF SIERRA DEL LAUREL AND SIERRA FRÍA, AGUASCALIENTES, MEXICO
ELEMENTOS FLORÍSTICOS DE INTERÉS PARA CONSERVACIÓN, PRESENTES EN LOS BOSQUES HÚMEDOS DE LA SIERRA DEL LAUREL Y LA SIERRA FRÍA, AGUASCALIENTES, MÉXICO
/ pages 435-457
Aguascalientes is located in the north central area of Mexico, where converge oak forests and pine-oak forests from the Sierra Madre Occidental, grasslands and xerophilous scrubs from the Zacatecas-San Luis Potosi Highland and tropical dry forest from the basins of river Juchipila and river Verde. Within this floristic diversity, we recorded a small set of elements indicating humid environments related to the mountain mesophilous forest, conserved into wet ravines of the Sierra Fría and Sierra del Laurel, as part of oak and riparian forests. To estimate the distribution of these species and their communities, we conducted a study using visual analysis techniques, Spot-5 multispectral satellite imagery and vegetation field sampling methods. Consistent with the results, we estimated that the sites with elements related to the mountain mesophilous forest is 1031.5 ha, distributed in 12 main localities. The sites with higher species richness are Boca Oscura and Los Alisos in the Sierra del Laurel. Among the most important species are Alnus acuminata, Cercocarpus macrophyllus, Clethra hartwegii, Garrya laurifolia, Litsea glaucescens, Populus tremuloides, Quercus castanea and Quercus candicans; which are common components found in temperate-wet forests of central and western Mexico.
MORPHOGENIC RESPONSES IN THE in vitro PROPAGATION OF PECAN (Carya illinoinensis [Wangenh] K. Koch)
RESPUESTAS MORFOGÉNICAS EN LA PROPAGACIÓN in vitro DE NOGAL PECANERO (Carya illinoinensis [Wangenh] K. Koch)
/ pages 469-481
Embryogenic and organogenic responses in pecan (Carya illinoinensis [Wangenh] K. Koch) were observed as a result of the in vitro cultivation of segments of leaves, axillary buds and zygotic embryos. Necrosis was controlled through the use of activated carbon (AC: 1%), polyvinylpyrrolidone (0.1 %), silver nitrate (AgNO3: 1 %), citric acid (150 mg·L-1) and ascorbic acid (100 mg·L-1, in both light and darkness. Murashige and Skoog base medium (MS) was used, supplemented with 0.40 mg·L-1 of thiamine, 100 mg·L-1 of myo-inositol, 3 % saccharose, incorporating 2,4-D for leaves, thidiazuron (TDZ) for embryos, and combinations of benzyladenine (BA), kinetin (KIN) naphthalenacetic acid (ANA) and indolebutyric acid (AIB) for axillary buds. Tissue necrosis was reduced by 75 % and 83 % adding CA and AgNO3, respectively. 33 % and 66 % of embryogenic callus originated from leaves, using 1 and 3 mg·L-1 of 2,4-D. The highest callus production (58 %) from embryos was obtained from the concentration of 3 mg·L-1 of TDZ. In axillary buds, the combination of KIN (3.0 μM), BA (1.0 μM) and AIB (0.3 μM) increased the number of leaves and seedlings, as well as shoot length.