A challenge in community ecology is the development of ecosystem baselines, allowing the assessment of the variation in the ecological dynamics through different temporal and spatial scales. To our ...best knowledge, no studies have been carried out in seasonal evergreen forests of Belize to establish a baseline for future monitoring. Hence, a floristic study of the woody plant species diversity and composition was carried out at the Billy Barquedier National Park (BBNP) to develop an ecosystemic baseline for the assessment of the originally implemented conservation strategies. A thorough floristic survey was performed from May to August 2015 in 42 rectangular plots (500 m2) randomly allocated along the 100 to 500 m elevation gradient of the BBNP. Species richness, diversity, composition, and aboveground biomass were assessed. Likewise, information of a series of indicators on protection and risk situation (e.g., IUCN Red List of threatened species, CITES categories), and restoration for each relevant species are also provided. The BBNP is an important forest with 67 woody species distributed in 30 plant families. Terminalia amazona and Corozo palm Attalea cohune are the most important species in the reserve, in terms of abundance, frequency, and biomass. A clear trend between biodiversity metrics, elevation, and aboveground biomass was noted. This study contributes to understand relevant ecological topics as well as provides key elements for the management and conservation of the BBNP area and Belize.
Background: Climate change is becoming more evident, and distribution models are useful tools to predict the effect it might cause on biodiversity.
Hypotheses: Under climate change scenarios, ...temperate forests species of the genus Pinus and Quercus will undergo reductions in their distribution area and changes in their spatial pattern.
Studied species: Arbutus xalapensis, Clethra mexicana, Pinus devoniana, Pinus oocarpa, Pinus teocote, Quercus acutifolia, Quercus castanea, Quercus crassifolia, Quercus elliptica, Quercus magnoliifolia and Quercus rugosa.
Study site: Oaxaca
Methods: Two scenarios were constructed, an optimistic one (SSP-1 and RCP 2-6) and a pessimistic one (SSP-5 and RCP 8.5) for the years 2030 and 2090. A total of 1,383 records and eight bioclimatic variables were used, along with seven learning algorithms, evaluated using ROC and TSS metrics.
Results: An ensemble model was obtained, in which the most important contributing variables were precipitation of the wettest quarter, mean annual temperature, minimum temperature of the coldest month and annual temperature range. The species that showed the highest ROC values were Clethra mexicana (0.91) and Arbutus xalapensis (0.89) with TSS values of 0.68 and 0.60, respectively.
Conclusions: Regardless of the scenario, by the year 2090 all species of Pinus and Quercus will reduce their potential distribution. Therefore, it is urgent to establish conservation policies.
Antecedentes: Los almacenes de carbono (C) de los bosques del mundo ascienden a 861 Pg; 44 % se encuentra en el suelo. A pesar de su importancia como reservorio, los estudios sobre carbono orgánico ...en el suelo (COS) en los bosques de México son escasos.
Pregunta: ¿El carbono orgánico en el suelo varía entre tipos de vegetación y tipos de suelo en los bosques de Durango?
Sitio de estudio: Bosques templados de Durango, México.
Métodos: Los datos de COS se obtuvieron de 399 sitios permanentes. Se colectaron muestras de hojarasca, horizonte de fermentación y de las capas de suelo de 0-30 y 30-60 cm. Los contenidos de C se determinaron en un analizador elemental. El cálculo de las incertidumbres se realizó siguiendo los procedimientos usados por la Comisión Nacional Forestal.
Resultados: El COS promedio estimado fue 8.48, 1.08, 110.62 y 53.44 Mg ha-1 en hojarasca, horizonte de fermentación, suelo de 0-30 y de 30-60 cm, respectivamente. Los almacenes promedio de C total en el suelo oscilaron desde 26.34 hasta 578.27 Mg ha-1 (incertidumbre: 6.31 %). La mayor variabilidad de los almacenes de COS se presentó en el bosque de pino.
Conclusiones: El tipo de bosque no influye en los almacenes de carbono orgánico en el suelo, pero sí el tipo de suelo. Los reservorios de COS en los bosques Durango son más altos comparados con el mismo tipo de vegetación en otras regiones del país.
La relación ahusamiento-volumen es indispensable para la planeación del manejo silvícola en los bosques con la finalidad de favorecer la distribución de los productos. Por esta razón, el objetivo del ...presente estudio fue generar un modelo compatible que permitiera estimar de forma precisa el volumen-ahusamiento de Abies religiosa en varias regiones de México. Se utilizaron 2608 datos en el análisis de la información y el modelo se ajustó simultáneamente mediante la regresión aparentemente no relacionada (RAN) para la estimación de parámetros compatibles. El modelo generó coeficientes de determinación ajustados superiores al 97 %, raíces del medio cuadrático menores al 0.40, sesgos menores a 0.11, con certeza para modelar cada región forestal; datos que fueron complementados con sus respectivos criterios de información Akaike (AIC). En la mayoría de casos el factor de forma de la especie fue neiloide a paraboloide, información que será de utilidad para la elaboración de inventarios forestales.
The role of invasive species in ecosystem functioning represents one of the main challenges in ecology.
is a successful cosmopolitan invasive species with negative effects on the ecological ...mechanisms that allow secondary succession. In this study, we evaluated the influence of
on secondary succession under different disturbances in a seasonal dry forest of the Yucatán Peninsula. We determined species richness, composition and the relative importance value in four sampling units. Fabaceae followed by Asteraceae, Meliaceae, Rubiaceae, Sapindaceae and Verbenaceae were the most species rich families. A dissimilarity analysis determined significant differences in beta diversity between sampling units. With a generalized linear model we found that species richness was best explained by site conditions, followed by calcium and soil organic matter. Also, the generalized linear model showed that abundance resulted in a strong correlation with site conditions and soil characteristics. Specific soil conditions related to phosphoro and calcium were also detected as beneficiary to the successional processes. Our results suggest that applying fire restriction and periodic cutting of the bracken fern, this can increase a higher diversity of species.
Lack of knowledge of individual tree growth in species-rich, mixed forest ecosystems impedes their sustainable management. In this study, species-specific models for predicting individual diameter at ...breast height (dbh) and total tree height (h) growth were developed for 30 tree species growing in mixed and uneven-aged forest stands in Durango, Mexico. Growth models were also developed for all pine, all oaks, and all other species of the genus Arbutus (strawberry trees). A database of 55,158 trees with remeasurements of dbh and h of a 5-year growth period was used to develop the models. The data were collected from 217 stem-mapped plots located in the Sierra Madre Occidental (Mexico). Weighted regression was used to remove heteroscedasticity from the species-specific dbh and h growth models using a power function of the tree size independent variables. The final models developed in the present study to predict dbh and total tree height growth included size variables, site factors, and competition variables in their formulation. The developed models fitted the data well and explained between 98 and 99% and of the observed variation of dbh, and between 77 and 98% of the observed variation of total tree height for the studied species and groups of species. The developed models can be used for estimating the individual dbh and h growth for the analyzed species and can be integrated in decision support tools for management planning in these mixed forest ecosystems.
Biometric systems are the basis of forest management and consist of a set of equations that describe the relationships between forest attributes and dendrometric variables. A systematic review of the ...state of the art of biometric systems in Mexico was carried out by a Mexican consortium (10 researchers), covering a period of 50 years ca (1970–2019), using the main scientific literature delivered by a systematic search (WoS, Scopus, Scielo, Redalyc) and a targeted search (theses, technical reports, etc.). A single selection criterion was established for the inclusion of information in the analysis: the document had to present at least one of the equations of interest. We found 376 documents containing 2524 equations for volume (69%), diameter (11%), height (9%) and site index (11%). These equations were developed for forest species mainly from temperate regions (88%), such as pine (66%) and oak (9%). Consequently, the Mexican states with the highest number of equations were Durango (28%), Chihuahua (17%), Hidalgo (13%) and Oaxaca (8%). Although large, the number of equations identified concentrated on a relatively small number of models: Schumacher & Hall and Fang et al. for volume; Chapman-Richards and Schumacher for site index and diameter; and Chapman-Richards and the allometric equation for height. An analysis of model fit, measured through R2, showed that, on average, the volume, diameter and site index models show high fit (R2 = 0.96), although this pattern was more consistent in the volume models. Publication bias was evaluated by means of a funnel plot analysis, with no apparent bias identified. A limitation of our study is that the information obtained is not updated to the present year; however, the 50-year trends allow us to assume that no recent significant changes in the patterns exist. Finally, we highlight the need to assess the predictive ability of the models to ensure accurate estimates to support better forest management decisions.
Accurate quantification of branch volume in trees is important for sustainable forest management, especially as these fractions are increasingly used for bioenergy, and for precise forest CO2 ...quantification. Whereas a large focus has been placed on the compatible estimation of tree taper and bole volume with and without bark, little effort has been made to develop models that allow a simultaneous prediction of these variables together with tree branch volume. In this study, 595 Pinus cooperi trees and 700 Pinus durangensis trees were sampled in pine-oak forests in the Sierra Madre Occidental, Mexico. A compatible system for predicting two segmented taper functions, over and under bark; the corresponding merchantable volumes; coarse branch volume and whole-tree volume was fitted using a modified continuous autoregressive structure to account for autocorrelation. The proposed compatible equations explained more than 97% of the observed variability in diameter over and under bark, volume over and under bark, and total tree volume and more than 64% of the observed variability in branch volume in both species. The method described can theoretically be replicated for any tree species, thus providing a better understanding of the patterns of volume distribution by components, potentially improving carbon accounting system and forest bioenergy planning.
Los modelos de índice de sitio representan una herramienta silvícola muy importante para clasificar la productividad de los bosques. El objetivo de este trabajo fue desarrollar ecuaciones dinámicas ...de índice de sitio derivadas, mediante el método de Diferencias Algebraicas Generalizadas (GADA), para cuatro especies de pino en la Sierra Norte del estado de Oaxaca, México. Para el ajuste de las ecuaciones se utilizaron datos de análisis de tronco de árboles de Pinus oaxacana, P. douglasiana, P. patula y P. pseudostrobus. Los árboles se seleccionaron en rodales mixtos e irregulares, intentando cubrir las diferentes calidades de estación presentes en las áreas sujetas a manejo forestal en los bosques de la Unidad de Manejo Forestal Regional 2001. Los ajustes se realizaron con el método iterativo y una estructura de error autoregresiva de tiempo continuo de segundo orden (CAR2), para corregir la autocorrelación del término del error. Los resultados indicaron que la formulación GADA del modelo de Bertalanffy-Richards puede ser utilizada para describir con precisión el índice de sitio de las cuatro especies estudiadas. La función desarrollada es polimórfica, dinámica, invariable con la edad de referencia y tiene múltiples asíntotas. El modelo genera, para las cuatro especies, estimaciones compatibles de índice de sitio y de altura dominante.
El objetivo de esta investigación fue cuantificar el carbono orgánico almacenado en el suelo del ejido La Victoria, Pueblo Nuevo, Durango. Muestras de suelo se colectaron en 108 sitios distribuidos ...en tres calidades de sitio, tres tratamientos silvícolas y tres profundidades de suelo. La determinación del contenido de carbono orgánico se realizó a través del método de Walkley y Black. Para identificar diferencias significativas de contenido de carbono orgánico en el suelo por calidad de estación, tratamiento silvícola y profundidad del suelo se realizaron análisis de varianza y comparación de medias mediante pruebas de Tukey al 95%. Los resultados mostraron un promedio de contenido de carbono orgánico en el suelo de 58.10 mg ha-1 y fue posible observar un aumento del carbono conforme mejora la calidad de estación. Los tratamientos silvícolas fueron no significativos y la tendencia mostrada fue una disminución del carbono orgánico conforme aumenta la profundidad del suelo.
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