Vulnerability in the offer of ecosystem services (SE) and the conservation of biodiversity in Antioquia

RESUMEN: La constante demanda de área para la producción y uso de Servicios Ecosistémicos, como consecuencia de la creciente población y consumo de recursos, conlleva a la pérdida de bosques y el declive de la biodiversidad. Con el objetivo de determinar el posible futuro de los bosques y la biodiversidad en el departamento de Antioquia (Colombia). En este artículo analizamos variables que generan presiones a los ecosistemas y su relación con las estrategias de conservación a través de áreas protegidas. Para conocer la conexión entre el mantenimiento de la oferta de Servicios Ecosistémicos, los incrementos entre los sectores productivos y algunas medidas de disminución de los servicios, dividimos las variables en tres grupos: i.) Variables para cuantificar la oferta de servicios de los ecosistemas; ii.) Variables de desarrollo económico; iii.) Variables de medición de la pérdida de funciones ecosistémicas. Mediante el uso de mapas de las subregiones de Antioquia, se pudieron conocer los porcentajes de ocupación de Servicios Ecosistémicos, entre ellos, la provisión de maderas y alimentos, la regulación (mitigación de emisiones de CO2, seguridad hídrica y fertilidad del suelo) y los servicios culturales (representatividad natural). Encontramos, a partir de todas las variables de consumo de Servicios Ecosistémicos consideradas, que ninguna variable presenta mayor peso respecto a las demás y que parece existir una relación entre pérdidas y ganancias de bosques con los niveles de las estrategias de conservación: en las subregiones donde las medidas de preservación son estrictas se presentan ganancias de bosque; y, por el contrario, en las subregiones donde predominan estrategias de desarrollo sostenible, como los Distritos de Manejo Integrado –DMI–, son constantes y mayores las tasas de deforestación. Los resultados obtenidos indican que los ecosistemas estratégicos son muy vulnerables al desarrollo económico y que las políticas de planeación del territorio fundamentadas en áreas protegidas con carácter de conservación estricta son una estrategia apropiada para disminuir las pérdidas de diversidad y el consecuente desabastecimiento de Servicios Ecosistémicos esenciales para la humanidad, como lo son la seguridad hídrica, el clima sostenible y el equilibrio global.ABSTRACT: The constant demand of area for the production and use of Ecosystem Services, as a consequence of the growing population and consumption of resources, determines the losses of forests and the decline of biodiversity. In order to determine the possible future of forests and biodiversity in the department of Antioquia (Colombia), in this article we analyze variables that generate pressures on ecosystems and their relationship with conservation strategies through protected areas. To know the link between maintaining the supply of ecosystemic services, productive clusters increase, and some actions to reduce such services, we divide the variables into three groups: i.) Variables to quantify the supply of ecosystemic services; ii.) Economic development variables; iii.) Variables for measuring the loss of ecosystemic functions. Through the use of maps of the subregions of Antioquia, it was possible to know the occupancy rates of ecosystemic services as follows: deforestation and the loss of food provision services, regulation (mitigation of CO2 emissions, water supply provision and fertility of soil) as well as cultural (natural representativeness). We found, from all the variables of consumption of ecosystemic services considered, that no variable has a greater weight in relation to the others and that there seems to be a relationship between losses and gains of forests driven by the levels of the conservation strategies, since, in the subregions where the preservation measures are strict, forest gains are present; and, on the contrary, in subregions where sustainable development strategies predominate, such as the Integrated Management Districts –DMI–, deforestation rates are constant and higher. The results obtained indicate that the strategic ecosystems of the planet are very vulnerable to economic development and that territorial planning policies based on protected areas with a strict conservation nature are an appropriate strategy to reduce diversity losses and the consequent shortage of ecosystemic services, essential for humanity such as water supply provision, sustainable climate and global equilibrium

PATRONES DE FRECUENCIA Y ABUNDANCIA DE SISTEMAS DE DISPERSIÓN DE PLANTAS EN BOSQUES COLOMBIANOS Y SU RELACIÓN CON LAS REGIONES GEOGRÁFICAS DEL PAÍS

The study of plant dispersal systems allows to go in depth in aspects that define the regeneration of forests, being essential to understand not only the population dynamics of plants but also the ecological relationships that emerge within ecosystems. In Colombia there is not a broad scale study showing the patterns of frequency and abundance of dispersal systems in different geographical regions (Amazonian, Andean, Caribbean, Upper Magdalena, Middle Magdalena, Orinoco, Pacific). Based on information of the identity and abundance of plants found in 101 vegetation plots of 1-ha, we explored the differences and associations in the frequency and abundance of dispersal systems between geographic regions. Additionally, we explored the importance value of families and genera per dispersal system, and the association between genera and geographic regions. The results show that environmental factors would be more important than the biogeographic history of the region in determining patterns of dispersal systems, reinforcing the importance of seed dispersal mediated by animals in tropical forests of different biogeographic regions.El estudio de los sistemas de dispersión de las plantas permite entender la regeneración de los bosques, la dinámica poblacional de las plantas y las relaciones ecológicas que emergen dentro de los ecosistemas. En el presente estudio analizamos los patrones de sistemas de dispersión de semillas para Colombia, en relación con las regiones geográficas Amazónica, Andina, Caribe, Magdalena Alto, Magdalena Medio, Orinoquía y Pacífica. A partir de la información sobre la identidad y abundancia de plantas encontradas en 101 parcelas de vegetación de 1-ha, se exploraron los cambios en la frecuencia relativa y abundancia relativa de sistemas de dispersión entre las regiones geográficas. Adicionalmente, se determinaron las afinidades florísticas entre las regiones, así como la representatividad de las familias y géneros por sistema de dispersión. La endozoocoria fue altamente representativa en diferentes niveles taxonómicos (especie, género y familia), y su representatividad cambió entre las distintas regiones geográficas. Estos cambios podrían explicarse a partir de diferencias ecológicas entre las regiones

Sensitivity of South American tropical forests to an extreme climate anomaly

The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha−1 per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected

Tree mode of death and mortality risk factors across Amazon forests

The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing > 3800 species from 189 long-term RAINFOR forest plots. While tree mortality rates vary greatly Amazon-wide, on average trees are as likely to die standing as they are broken or uprooted—modes of death with different ecological consequences. Species-level growth rate is the single most important predictor of tree death in Amazonia, with faster-growing species being at higher risk. Within species, however, the slowest-growing trees are at greatest risk while the effect of tree size varies across the basin. In the driest Amazonian region species-level bioclimatic distributional patterns also predict the risk of death, suggesting that these forests are experiencing climatic conditions beyond their adaptative limits. These results provide not only a holistic pan-Amazonian picture of tree death but large-scale evidence for the overarching importance of the growth–survival trade-off in driving tropical tree mortality

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

The number of tree species on Earth

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global groundsourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are 73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

The number of tree species on Earth.

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

Tropical forests in the Americas are changing too slowly to track climate change

Understanding the capacity of forests to adapt to climate change is of pivotal importance for conservation science, yet this is still widely unknown. This knowledge gap is particularly acute in high-biodiversity tropical forests. Here, we examined how tropical forests of the Americas have shifted community trait composition in recent decades as a response to changes in climate. Based on historical trait-climate relationships, we found that, overall, the studied functional traits show shifts of less than 8% of what would be expected given the observed changes in climate. However, the recruit assemblage shows shifts of 21% relative to climate change expectation. The most diverse forests on Earth are changing in functional trait composition but at a rate that is fundamentally insufficient to track climate change

The number of tree species on Earth.

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

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