Population genetic structure and dispersal of Pinus occidentalis in the Dominican Republic by chloroplastic SSR with implications for its conservation, management, and reforestation

<i>Pinus occidentalis</i> is the dominant species of forest ecosystems in the Dominican Republic, located between 200 and 3000 meters above sea level, with extensive and overexploited natural populations. However, over the years, various restoration plans have been performed, which could affect the genetic structure of <i>P. occidentalis</i>. Despite being the species with the highest occurrence in the Dominican forests, there is no existing information on genetic structure and molecular characterization among natural populations with limited information on both phenological and productive characterization. In this study, the genetic structure, diversity, and gene flow of the five <i>P. occidentalis</i> natural populations of the Dominican Republic were determined using microsatellite markers. A total of 145 individuals were genotyped with eight polymorphic chloroplastic microsatellites, producing an average of 41 haplotypes with high genetic diversity across populations (H_E = 0.90). Significant population genetic structure was found between populations (F_ST = 0.123). These results reflect the impact of reforestation programs on natural populations and diluting the natural genetic signature. Analysis of population genetic data is, therefore, crucial for the breeding and conservation programs of <i>P. occidentalis</i> in the country.

Diversidad, Estructura y Composición de la Flora Vascular del Campus de la Universidad ISA, Santiago, República Dominicana

Se presenta la lista de especies, estructura y composición de la flora vascular del Campus de la Universidad ISA, Santiago, República Dominicana. La lista incluye el nombre científico, la familia botánica, la forma de vida, el estatus de conservación y la distribución geográfica, así como algunos de sus principales usos etnobotánicos. El Campus alberga un total de 312 especies de plantas vasculares distribuidas en 81 familias y 254 géneros. Las familias con mayor riqueza son Fabaceae (29), Poaceae (19), Asteraceae y Malvaceae (15), Arecaceae (14), Euphorbiaceae (12), Asparagaceae (10), Araceae, Bignoniaceae y Myrtaceae (9). Las formas de vida más representadas fueron la arbórea 106 (34 %) y la herbácea 95 (30 %), respectivamente. De las 312 especies, 6 son endémicas, 124 nativas y 183 introducidas, de las cuales 14 son consideradas como potencialmente invasoras. Ocho taxones se encuentran bajo alguna categoría de amenaza, de acuerdo con los criterios de la UICN y la Lista Roja de la República Dominicana. Estas especies son: Agave vivipara L., Dypsis decaryi (Jum.) Beentje & J.Dransf, Jacaranda mimosifolia D.Don., Swietenia macrophylla King, bajo la categoría de Vulnerable (VU), Coffea arabica L., Pinus occidentalis Sw. Bajo la categoría de En Peligro (EN) y Leuenbergeria quisqueyana (Alain) Lodé.

Allometric equations for total aboveground dry biomass and carbon content of Pinus occidentalis trees

Although precise species-specific aboveground tree biomass equations are needed in the Dominican Republic to quantify potential carbon storage in the context of climate change and sustainable forest management, there has been a lack of available information concerning total aboveground biomass and/or carbon content for naturally occurring Pinus occidentalis trees. The objectives of the study were to develop species-specific allometric biomass models for P. occidentalis, as well as to assess variation in carbon concentration among stem plus bark, branches and foliage by means of chemical analyses. Predictor variables included diameter at breast height (DBH) and total tree height (H), alone and in combination. Model fitting methods employing linear and nonlinear regression techniques were used and evaluated based on goodness-of-fit criteria. Two competing biomass models produced similar goodness-of-fit statistics: model 4, fitted by the Weighted Non-linear Least Squares technique, , and model 6, fitted by modeling the variance component and applying the Maximum Likelihood method, . Average carbon concentration (%) was highest in foliage tissue (49.8%), followed by branches (46.37%) and, lastly, stem plus bark (45.95%). On average, each individual tree is storing 175 kg of total aboveground carbon. To our knowledge, this is the first account reporting carbon fraction for this tropical species. Calculated wood carbon fractions from the study can be easily incorporated into forest C accounting, and may reduce errors in forest C valuations, which nowadays are performed using global estimates published elsewhere.

Forest change within and outside protected areas in the Dominican Republic, 2000-2016

We used Landsat-based estimates of tree cover change to document the loss and gain of forest in the Dominican Republic between 2000 and 2016. Overall, 2,795 km2 of forest were lost, with forest gain occurring on only 393 km2, yielding a net loss of 2,402 km2 of forest, a decline of 11.1% or 0.7% per year. Deforestation occurred in all of the major forest types in the country, and ranged from a 13% decline in the area of semi-moist broadleaf forest to a 5.9% loss of cloud forest, mostly attributed to agriculture. Fire was a significant driver of forest loss only in Hispaniolan pine (Pinus occidentalis) forests and, to a lesser extent, in adjacent cloud forest. Deforestation rates were lower within protected areas, especially in dry and semi-moist broadleaf forests at lower elevations. Protected areas had a smaller, and generally negligible, effect on rates of forest loss in pine forest and cloud forest, largely due to the effects of several large wildfires. Overall, rates of deforestation in the Dominican Republic were higher than regional averages from across the Neotropics and appeared to have accelerated during the later years of our study period. Stemming deforestation will likely require enforcement of prohibitions on large-scale agricultural production within protected areas and development of alternatives to short-cycle, shifting agriculture.

Toward Sustainable Cultivation of Pinus occidentalis Swartz in Haiti: Effects of Alternative Growing Media and Containers on Seedling Growth and Foliar Chemistry

Haiti has suffered great losses from deforestation, with little forest cover remaining today. Current reforestation efforts focus on seedling quantity rather than quality. This study examined limitations to the production of high-quality seedlings of the endemic Hispaniolan pine (Pinus occidentalis Swartz). Recognizing the importance of applying sustainable development principles to pine forest restoration, the effects of growing media and container types on seedling growth were evaluated with the goal of developing a propagation protocol to produce high-quality seedlings using economically feasible nursery practices. With regard to growing media, seedlings grew best in compost-based media amended with sand. Topsoil, widely used in nurseries throughout Haiti, produced the smallest seedlings overall. Despite a low water holding capacity and limited manganese, compost-based media provided adequate levels of essential mineral nutrients (particularly nitrogen), which allowed for sufficient seedling nutrition. Seedling shoot and root growth, as well as the ratio of shoot biomass to root biomass, were greater in polybags relative to D40s. Results indicate that economically feasible improvements to existing nursery practices in Haiti can improve the early growth rates of P. occidentalis seedlings.

Factores edáficos-fisiográficos y calidad de sitio del Pinus occidentalis Sw.

La estimación de la calidad de sitios para la producción forestal normalmente se logra aprovechando la presencia de árboles que exhiben diferentes patrones de crecimiento en altura y desarrollando ecuaciones que relacionan su altura y edad. Sin embargo, hay lugares desprovistos de árboles donde la inversión en bosques productivos es factible; más aún si se puede estimar a priori la calidad potencial de regenerar determinadas especies forestales. Se desarrollaron modelos matemáticos regresivos para estimar el índice de sitio en rodales naturales de Pinus occidentalis Sw., en las principales regiones productivas de Republica Dominicana, estableciendo también la relación entre el índice de sitio y variables edáficas y fisiográficas. Los modelos permiten evaluar el potencial productivo en lugares desprovistos de árboles. No se encontraron diferencias significativas (α 0.01) entre los índices de sitio promediados por parcela en cada localidad, pero sí se obtuvo una correlación significativa entre el índice de sitio, altura sobre el nivel del mar y exposición de la respectivamente. Una correlación significativa fue también encontrada entre índice de sitio y contenido de materia orgánica , sodio y potasio . Las variables elevación sobre el nivel del mar y azimut resultaron estadísticamente significativas y pueden utilizarse para predecir el potencial productivo de lugares donde no existen árboles. La estimación del potencial productivo mediante variables edáficas y fisiográficas para los rodales naturales de P. occidentalis Sw. en las regiones productivas, constituye una herramienta indispensable en el manejo sostenible de estas áreas boscosas.

Caracterización de la morfología de la semilla de Pinus Occidentalis Swartz

La gran biodiversidad de especies de plantas en la isla La Española, hace conveniente la elaboración de trabajos que permitan identificar las familias, géneros y especies, a partir de diversos caracteres, como los anatómicos. En la República Dominicana se carece de investigaciones sobre las semillas de las especies endémicas. Es importante profundizar en estudios morfológicos y anatómicos de las semillas de nuestras especies y emplearlas con diferentes fines, como orientación taxonómica, conocer más sobre su ecología, entre otros. En nuestro trabajo tratamos de utilizar un carácter relevante de Pinus occidentalis, como es su semilla. El presente estudio nos permite conocer sobre la superficie de la semilla de Pinus occidentalis, pues la morfología de la semilla juega un papel importante en la dispersión de la especie.