Estado del conocimiento y aportes a la flora vascular del bosque seco del Tolima

In Colombia, dry tropical forests represents one of the most degraded, fragmented and less studied ecosystems, constituting a priority research element, therefore, in this paper, we defined the list of plants for dry forests in the department of Tolima supported by TOLI Herbarium collections and records of the authors, which were obtained in botanical expeditions over the last 4 years at these forests. The best sampled municipalities and the places without collections were defined. For the first time for this ecosystem, we registered in Colombia and South America Ophellantha spinosa Standl in The Neme Reserve in Coello, in dry forest in Tolima to Anthodon decussatum Ruiz & Pav., Gustavia santanderiensis R.Knuth and Simira rubescens (Benth.) Bremek. ex Steyerm. During curatorial process of collection, two isotypes were found to be determined, corresponding to Trichilia oligofoliolata M. E. Morales and Trichilia carinata M. E. Morales, these were considered endemic to the dry forests of northern Tolima. We conclude that the best collected places are agricultural research centers and they have generally historical collections including mainly species associated with crops such as weeds and grassland. Thus, forests that are not part of large monocultures in the fertile terraces are partly unexplored and could harbor important and unknown species to the area.En Colombia los bosques secos representan uno de los ecosistemas más degradados, fragmentados y menos estudiados, lo cual hace que se enmarque en un factor prioritario para la investigación, por esto en este trabajo se definió el listado de plantas para los bosques secos en el departamento del Tolima, empleando en ello las colecciones de los Herbarios TOLI y COL. Se determinaron los municipios mejor muestreados y los lugares sin colectas. Se registra para el Tolima y segunda vez para Colombia Acidocroton gentryi Fern. Alonso & R. Jaram. (Euphorbiaceae) en la Reserva El Neme en Coello; para bosque seco en Tolima, Anthodon decussatum Ruiz & Pav. (Celastraceae), Gustavia santanderiensis R.Knuth (Lecythidaceae), el género Palmorchis de la familia Orchidaceae y Simira rubescens (Benth.) Bremek. ex Steyerm. (Rubiaceae). Se concluye que los lugares más colectados obedecen a centros de estudios agrícolas y que son, en general, colectas históricas que incluyen principalmente especies asociadas a cultivos como Herbáceos y pastizales. De esta forma, los bosques que no se encuentran relacionados con los grandes monocultivos de las terrazas fértiles, siguen parcialmente inexplorados y pueden albergar importantes especies desconocidas para la zona

PATRONES DE ARQUITECTURA FOLIAR ASOCIADOS AL CRECIMIENTO FUNCIONAL DE CINCO ESPECIES LEÑOSAS NATIVAS DE LA CORDILLERA ORIENTAL UTILIZADAS EN RESTAURACIÓN ECOLÓGICA EN LA SABANA DE BOGOTÁ

This research was carried out in La Poma Ecological Park, which is located on the Sabana de Bogotá and corresponds to an area of Lower Montane dry forest. Frequent incidences of frost means that it is a challenging environment for vegetation growth. Leaf components, patterns of canopy architecture and functional growth parameters were evaluated and characterized for populations of Abatia parviflora (Ap), Dodonaea viscosa (Dv), Escallonia paniculata(Ep), Baccharis macrantha (Bm) and Quercus humboldtii (Qh) that ranged in age from one to ten years. We hypothesized that particular growth tendencies were associated with a specific architectural pattern. Morphometric leaf, canopy architecture and functional growth variables were evaluated for these species. An Anova (P <0.05) was performed for each variable along with a multiple range Tukey test that separated the means. We found that the species with higher photosynthetic efficiency and higher dry matter accumulation capacity expressed in biomass were Qh and Dv. These species have an erectophil canopy with the highest light absorption. The other species (Ap, Ep, and Bm) have planophil and plagiophil canopies that have a lower productive capacity. This work provides information on the potential use of woody shrub species in environments where trees have restricted growth.Esta investigación se realizó en el Parque Ecológico la Poma que hace parte de los paisajes de la Sabana de Bogotá y corresponde a un bosque seco Montano Bajo (bs-Mb), con presencia recurrente de heladas, lo que genera un ambiente crítico para el crecimiento de la vegetación. Se evaluó y se caracterizó el componente foliar, los patrones que definen la arquitectura de dosel y los parámetros de crecimiento funcional, para poblaciones de las especies Abatia parviflora (Ap), Dodonaea viscosa (Dv), Escallonia paniculata (Ep), Baccharis macrantha (Bm)y Quercus humboldtii (Qh), con edades entre uno y diez años, bajo la hipótesis que plantea la existencia de tendencias particulares de crecimiento asociadas a un patrón arquitectural específico. Se evaluaron variables de tipo morfométrico foliar, variables para la caracterización de la arquitectura de dosel y variables de crecimiento funcional para las especies mencionadas. Para cada variable se realizó un análisis de varianza (p < 0.05) y en el test de rango múltiple se utilizó la prueba Tukey para la separación de las medias. Como resultado se encontró que las especies con mayor eficiencia fotosintética, y por consiguiente, con mayor capacidad de acumulación de materia seca expresada en la biomasa fueron Qh y Dv, las cuales presentaron un dosel de tipo erectófilo que generó la mayor absorción lumínica. Las demás especies (Ap, Ep y Bm) tienen doseles planófilos y plagiófilos que se pueden ligar a una menor capacidad productiva. Este trabajo vislumbra el potencial de las especies leñosas arbustivas para ser utilizadas en ambientes donde los arboles tienen restringido su crecimiento

INDICADORES MORFOMÉTRICOS FOLIARES PARA LA DETECCIÓN TEMPRANA DEL ESTRÉS HÍDRICO DE Gmelina arborea Roxb. EN SISTEMAS AGROFORESTALES, SANTAFÉ DE ANTIOQUIA

Leaf asymmetry was assessed in individuals of Gmelina arborea Roxb. growing under different soil water conditions in a dry forest agroforestry system (AFS), in Santafé de Antioquia. Leaf asymmetry was correlated with additional morphometric parameters, such as angle of insertion of the petiole in the leaf in mature individuals and the ratio of the number of teeth on the edge of the blade in juvenile leaves to propose new indicators of early stage stress. The models generated had R2 values of above 75 %, which support their use in identifying developmental instability as an early indicator of water stress. Similarly, leaf diversity was assessed between the two phenotypes of leaves (ML and JL), with conventional morphometric variables (length of the midrib, leaf perimeter, specific leaf area and dry matter), because they are characters related to leaf form and function. There were marked differences in form and behavior between the two types of leaf indicating a further source of instability evident from leaf ontogeny. The results of this work will allow the optimization of management strategies of G. arborea in the AFS as an early indicator of water stress.En esta investigación se evaluó la asimetría foliar (ASF) en individuos deGmelina arborea Roxb., establecidos en sistemas agroforestales (SAF), en áreas de bosque seco tropical, en el municipio de Santafé de Antioquia. Estos individuos crecen bajo diferentes condiciones hídricas del suelo. La ASF se correlacionó con nuevos parámetros de tipo morfométrico como el ángulo de inserción del peciolo en la lámina foliar (AIP) en individuos maduros y la razón entre el número de dientes del borde de la lámina (RDF) en las hojas de individuos juveniles, propuestos como nuevos indicadores del estado temprano de estrés en la especie. Los modelos generados presentaron valores de R2superiores al 75 %, lo que soporta su utilización como indicadores tempranos del estrés hídrico en G. arborea. Adicionalmente, se evaluó la diversidad foliar entre los dos tipos de hojas (HM y HJ), con variables morfométricas convencionales, tales como la longitud de la nervadura principal (L), perímetro de la hoja (P), área foliar específica (AFE) y materia seca (DW), puesto que son caracteres relacionados con la forma y funcionalidad foliar. De lo anterior se dedujo que existen marcadas diferencias en forma y comportamiento entre los dos tipos de hojas. Los resultados de este trabajo permitirán la optimización de estrategias de manejo de G. arborea en el SAF, gracias a la identificación temprana de la presencia de este tipo de estrés. Esto permitiría mantener permanentemente el dosel de los árboles y así mejorar el ambiente de productividad de los cultivos agrícolas asociados

Forest biomass density across large climate gradients in northern South America is related to water availability but not with temperature

Understanding and predicting the likely response of ecosystems to climate change are crucial challenges for ecology and for conservation biology. Nowhere is this challenge greater than in the tropics as these forests store more than half the total atmospheric carbon stock in their biomass. Biomass is determined by the balance between biomass inputs (i.e., growth) and outputs (mortality). We can expect therefore that conditions that favor high growth rates, such as abundant water supply, warmth, and nutrient-rich soils will tend to correlate with high biomass stocks. Our main objective is to describe the patterns of above ground biomass (AGB) stocks across major tropical forests across climatic gradients in Northwestern South America. We gathered data from 200 plots across the region, at elevations ranging between 0 to 3400 m. We estimated AGB based on allometric equations and values for stem density, basal area, and wood density weighted by basal area at the plotlevel. We used two groups of climatic variables, namely mean annual temperature and actual evapotranspiration as surrogates of environmental energy, and annual precipitation, precipitation seasonality, and water availability as surrogates of water availability. We found that AGB is more closely related to water availability variables than to energy variables. In northwest South America, water availability influences carbon stocks principally by determining stand structure, i.e. basal area. When water deficits increase in tropical forests we can expect negative impact on biomass and hence carbon storage

Casos de estudio en México y Latinoamérica

Ante la presencia de conflictos sociales y territoriales, las comunidades organizadas buscan estrategias de solución y confrontación. Es el estudio de dichos movimientos, lo que motiva a la publicación de éste libro: Respuestas comunitarias ante conflictos ambientales. Casos de estudio en México y Latinoamérica, reúne catorce textos que analizan las respuestas sociales y documentan la acción colectiva de comunidades que se han organizado para autogestionar soluciones ante conflictos territoriales, económicos y ambientales, en su propio entorno. Las aportaciones de investigadores y activistas, desde enfoques teóricos y metodológicos particulares, exponen casos de estudio sobre organizaciones formales e informales que se han conformado para afrontar los retos que representan proyectos productivos como fábricas cementeras, mineras, puertos, productores de energía, entre otros. Los enfoques analíticos tocan también temas nodales en el estudio de la acción colectiva como la ética, el despojo, los derechos humanos y las estrategias de comunicación y visibilización. Este material, que reúne estudios hechos en distintos lugares de México y Latinoamérica, es un compendio de métodos de investigación y un acercamiento al estudio de los movimientos sociales.UAEMEX, CONACyT, SE

Large-scale patterns of turnover and basal area change in Andean forests

General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century

The pace of life for forest trees.

Tree growth and longevity trade-offs fundamentally shape the terrestrial carbon balance. Yet, we lack a unified understanding of how such trade-offs vary across the world's forests. By mapping life history traits for a wide range of species across the Americas, we reveal considerable variation in life expectancies from 10 centimeters in diameter (ranging from 1.3 to 3195 years) and show that the pace of life for trees can be accurately classified into four demographic functional types. We found emergent patterns in the strength of trade-offs between growth and longevity across a temperature gradient. Furthermore, we show that the diversity of life history traits varies predictably across forest biomes, giving rise to a positive relationship between trait diversity and productivity. Our pan-latitudinal assessment provides new insights into the demographic mechanisms that govern the carbon turnover rate across forest biomes

Evenness mediates the global relationship between forest productivity and richness

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale. 2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship. 3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive. 4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions

Native diversity buffers against severity of non-native tree invasions

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species$^{1,2}$. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies$^{3,4}$. Here, leveraging global tree databases$^{5,6,7}$, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions