Colombian Amazon Research Articles

‘Moving South’: Late Pleistocene Plant Exploitation and the Importance of Palm in the Colombian Amazon

The role of plants in early human migrations across the globe has received little attention compared to big game hunting. Tropical forests in particular have been seen as a barrier for Late Pleistocene human dispersals due to perceived difficulties in obtaining sufficient subsistence resources. Archaeobotanical data from the Cerro Azul rock outcrop in the Colombian Amazon details Late Pleistocene plant exploitation providing insight into early human subsistence in the tropical forest. The dominance of palm taxa in the assemblage, dating from 12.5 ka BP, allows us to speculate on processes of ecological knowledge transfer and the identification of edible resources in a novel environment. Following the hypothesis of Martin Jones from his 2009 work, “Moving North: archaeobotanical evidence for plant diet in Middle and Upper Paleolithic Europe”, we contend that the instantly recognizable and economically useful palm family (Arecaceae) provided a “gateway” to the unknown resources of the Amazon forest.

Soil enzyme responses to land use change in the tropical rainforest of the Colombian Amazon region.

Soil enzymes mediate key processes and functions of the soils, such as organic matter decomposition and nutrient cycling in both natural and agricultural ecosystems. Here, we studied the activity of five extracellular soil enzymes involved in the C, N, and P-mineralizing process in both litter and surface soil layer of rainforest in the northwest region of the Colombian Amazon and the response of those soil enzymes to land use change. The experimental study design included six study sites for comparing long-term pasture systems to native forest and regeneration practices after pasture, within the main landscapes of the region, mountain and hill landscapes separately. Results showed considerable enzymatic activity in the litter layer of the forest, highlighting the vital role of this compartment in the nutrient cycling of low fertility soils from tropical regions. With the land use transition to pastures, changes in soil enzymatic activities were driven by the management of pastures, with SOC and N losses and reduced absolute activity of soil enzymes in long-term pastures under continuous grazing (25 years). However, the enzyme activities expressed per unit of SOC did not show changes in C and N-acquiring enzymes, suggesting a higher mineralization potential in pastures. Enzymatic stoichiometry analysis indicated a microbial P limitation that could lead to a high catabolic activity with a potential increase in the use of SOC by microbial communities in the search for P, thus affecting soil C sequestration, soil quality and the provision of soil-related ecosystem services.

Can Rubber Crop Systems Recover Termite Diversity in Previously Degraded Pastures in the Colombian Amazon Region?

Livestock production extension in Amazon has caused deforestation and soil degradation, with negative consequences on diversity and environmental services. Recently, rubber crops have been established in deteriorated soils of the Colombian Amazon as an option to restore hectares of unproductive degraded pastures. Bioindicator insects, such as termites, have been used to assess soil quality and fertility restoration. This study evaluated differences in termite abundance, species richness, and community composition in three different rubber crop systems as an indirect way of evaluating soil diversity restoring. Three rubber crop systems were sampled: clonal fields (rubber monocultures with different rubber clones), traditional commercial rubber plantations (rubber monocultures with just one rubber clone), and mixed plantations (rubber fields intercropped with copoazú fruit trees). Additionally, pastures in use for livestock production and natural forest relicts were compared to rubber crop systems, to serve as reference habitats. Termites were sampled using a 105-m transect method. Alpha diversity and beta diversity were estimated and compared between rubber crops and reference habitats. A total of 80 termite species belonging to two families were collected. Mixed plantations and pastures presented the lowest diversity rates. Species richness in rubber crop systems was 39% higher than that in pastures and included 72% of the termite species found in natural forests. Indicator species analysis associated soil-feeding termites with less diverse habitats and wood-feeding termites with high diverse habitats. Our results demonstrate that termite recovery will depend on the farming system selected and the agricultural practices implemented in the field, with some rubber crop systems, like commercial rubber plantations and clonal fields, recovering termite diversity better than others, such as mixed plantations.

New species of Stenopterobia (Bacillariophyta) from Colombia and Peru, and new nomenclatural transfers in Iconella

During a survey of diatoms from the Colombian and Peruvian Amazon, we encountered many specimens of the genus Stenopterobia in periphyton and plankton samples. These diatoms were assigned to three different taxa, two with sigmoid valves and the other one with straight valves. The comparison of their valve morphologies with similar taxa described in the literature revealed that they do not correspond to any previously known taxa. They are described herein as Stenopoterobia caquetaensis sp. nov., S. colombiana sp. nov. and S. amazonica sp. nov. We maintain this genus assignment since the new taxa, as well as other species currently in Stenopterobia, exhibit differences from Iconella, a genus to which several Stenopterobia species were recently transferred. Differences exist between the two genera in their ultrastructural features, such as plain internal valve face and unrimmed internal areolar openings, which do not fully conform to the description of Iconella. Additionally, the robustoid Surirella rafaelii and S. tayronarum, recently described from Colombia, are transferred to Iconella.

The risk of unintended deforestation from scaling sustainable livestock production systems

AbstractSilvopastoral systems (SPS)—production systems integrating trees, forages, and livestock within the same land area—are recognized as critical for reducing tropical deforestation and improving livelihoods, ecosystem services, and carbon sinks. Yet, research on how scaling SPS influences forest cover changes at large geographical scales is scant. Our study delves deeper into the interlinkages between scaling SPS and deforestation. In two surveys conducted among 144 Colombian Amazon livestock producers with traditional or SPS farms, we assessed changes in herd composition between 2016 and 2020. Results showed a change in herd composition, with fewer males and more cows/heifers, suggesting a shift toward specializing in milk production, which, with the appropriate environmental incentives and safeguards, would unlikely broaden deforestation. However, interlinkages between the dairy and beef value chains suggest that extra male cattle from SPS intensification would be moved for fattening as a source of beef to new pastures at the forest border. If SPS scaling interventions in the Colombian Amazon are to be truly deforestation‐free, they need to be designed based on a clear understanding of the interlinkages between food and land systems. Therefore, policies advancing the livestock and land‐use agenda must create mechanisms that support deforestation‐free livestock intensification, based on biophysical and socioeconomic evaluations.

Use of freeze-dried trivalent antivenom to neutralize the toxic activities of Bothrops atrox snake venoms from the Amazon

In Brazil, antivenom for snakebite is currently formulated in liquid form and requires storage at 4 °C. Here, a new freeze-dried trivalent antivenom, which would enable cold-chain free storage, was determined to have efficacy in neutralizing the biological activities of Bothrops atrox venoms from Manaus (Brazil) and Leticia (Colombia), exhibiting an efficacy similar to those of currently available liquid Bothrops antivenoms. These results indicate that freeze-dried trivalent antivenom may be beneficial for applications in the Brazilian and Colombian Amazon regions.

Terra Preta Properties in Northwestern Amazonia (Colombia)

Whereas many researchers still approach Terra Preta (TP) as a soil category, new evidence suggests that TP refers to a directional grading of soil property changes (i.e., color, pH, nutrients, etc.) within human-made soils, originating from human activities in pre-Columbian times. Currently, most TP research focuses on the Brazilian part of the Amazon basin, but only little information is available on TP soils in the Colombian Amazon. Here, we sampled four TP and surrounding soils in the Colombian Amazon region at different soil depths and analyzed them for (i) general soil properties such as color, pH and texture, (ii) soil organic carbon and black carbon (BC) contents, the latter using benzene polycarboxylic acids as molecular marker, (iii) phosphorus availability based on sequential fractionation, and (iv) microbial residue contents using amino sugars. Our data from Colombia’s middle Caquetá River and Leticia confirmed that SOC, BC, and total P were present in significantly higher concentrations in the TP areas than the surrounding soils, while pH values and microbial residue contents were unchanged. The enrichment of P forms comprised both easily extractable and stable P pools, which both dominated to a different degree, both in TP and adjacent soils. The different degree of SOC, BC and P enrichment suggests different amounts of waste disposal by the ancient populations at different TP sites, now warranting further research for reconstructing ancient population sizes from TP chemical analyses.

The effects of armed conflict on forest cover changes across temporal and spatial scales in the Colombian Amazon

The Amazon rainforest covers roughly 40% of Colombia’s territory and has important global ecological functions. For more than 50 years, an internal war in the country has shaped this region. Peace negotiations between the government and the Revolutionary Armed Forces of Colombia (FARC) initiated in 2012 resulted in a progressive de-escalation of violence and a complete ceasefire in 2016. This study explores the role of different deforestation drivers including armed conflict variables, in explaining deforestation for three periods between 2001 and 2015. Iterative regression analyses were carried out for two spatial extents: the entire Colombian Amazon and a subset area which was most affected by deforestation. The results show that conflict variables have positive relationships with deforestation; yet, they are not among the main variables explaining deforestation. Accessibility and biophysical variables explain more variation. Nevertheless, conflict variables show divergent influence on deforestation depending on the period and scale of analysis. Based on these results, we develop deforestation risk maps to inform the design of forest conservation efforts in the post-conflict period.

Participatory mapping reveals socioeconomic drivers of forest fires in protected areas of the post‐conflict Colombian Amazon

Abstract Wildfires have increased in protected areas (PAs) of the Colombian Amazon following the 2016 peace agreement between the Government and the Revolutionary Armed Forced of Colombia (FARC—Spanish acronym). Recent study efforts to understand this issue suffer from data scarcity and limited consultation of local stakeholder perspectives on factors affecting wildfires. This study uses a social–ecological systems framework to investigate local perceptions of factors driving and/or preventing wildfires in the Los Picachos, La Macarena and Tinigua PAs, which are shared by two Amazonian departments experiencing wildfire increase. Four stakeholder categories were selected to represent varied and possibly conflicting interests: cattle ranchers, the national park service, local authorities and cross‐sectional stakeholders. We combined a participative mapping approach with interviews to illustrate stakeholder perceptions of interactions between key variables in graphical causal models. Network analyses were used to determine areas of agreement on key variables, and to compare local priorities with those of key informants at the national level. Local stakeholders and key informants widely agreed on the roles of extensive cattle ranching and land grabbing as key drivers of wildfires. The analysis identified areas for further research into wildfire occurrence within PAs. These include lack of governance and untitled land, as well as the effects of poor access to basic public services on unsustainable ranching methods. This study revealed contested opinions between ranchers and other stakeholders over interactions between ranching, roads and illicit crops, and consequently their effects on wildfire occurrence. This indicates the need for cautious implementation of the National Development Plan, prioritising road maintenance over expansion, integrating arable alternatives to cattle ranching and considering multiple stakeholders in regional decision‐making around wildfire reduction. The strengths and limitations of the participative mapping approach employed here are discussed with a view to aiding decision‐making in post‐conflict regions of the Global South.

Prediction model for sap flow in cacao trees under different radiation intensities in the western Colombian Amazon

In this study, we measured diurnal patterns of sap flow (Vs) in cacao trees growing in three types of agroforestry systems (AFs) that differ in the incident solar radiation they receive. We modeled the relationship of Vs with several microclimatic characteristics of the AFs using mixed linear models. We characterized microclimatic variables that may have an effect on diurnal patterns of sap flow: air relative humidity, air temperature, photosynthetically active radiation and vapor pressure deficit. Overall, our model predicted the differences between cacao Vs in the three different AFs, with cacao plants with dense Musaceae plantation and high mean diurnal incident radiation (HPAR) displaying the highest differences compared to the other agroforestry arrangements. The model was also able to predict situations such as nocturnal transpiration in HPAR and inverse nocturnal sap flows indicative of hydraulic redistribution in the other AFs receiving less incident radiation. Overall, the model we present here can be a useful and cost-effective tool for predicting transpiration and water use in cacao trees, as well as for managing cacao agroforestry systems in the Amazon rainforest.

Colombian climatology in CMIP5/CMIP6 models: Persistent biases and improvements

Northern South America is among the regions with the highest vulnerability to climate change. General Circulation Models (GCMs) are among the different tools considered to analyze the impacts of climate change. In particular, GCMs have been proved to provide useful information, although they exhibit systematic biases and fail in reproducing regional climate, particularly in terrains with complex topography. This work evaluates the performance of GCMs included in the fifth and sixth phases of the Coupled Model Intercomparison Project (CMIP), representing the annual cycle of precipitation and air surface temperature in Colombia. To evaluate this, we consider different observational and reanalysis datasets, including in situ gauges from the Colombian Meteorological Institute. Our results indicate that although the most recent generation of GCMs (CMIP6) show improvements with respect to the previous generation (CMIP5), they still have systematic biases in representing the Intertropical Convergence Zone and elevation-dependent processes, which highly determine intra-annual precipitation and air surface temperature in Colombia. In addition, CMIP6 models have larger biases in temperature over the Andes than CMIP5. We also analyze climate projections by the end of the 21st century according to the CMIP5/CMIP6 simulations under the highest greenhouse gases emission scenarios. Models show projections toward warmer air surface temperatures and mixed changes of precipitation, with decreases of precipitation over the Orinoco and Colombian Amazon in September-November and increases over the eastern equatorial Pacific during the entire year.

Methyl acetate, a highly volatile floral semiochemical mediating specialized plant-beetle interactions.

Olfactory signaling is key to the reproductive biology of entomophilous palms. Both pollinating and specialized herbivorous insects are attracted to fragrance-emitting palm inflorescences that function as reliable food sources, as well as mating and oviposition sites. In the present study, we characterized the floral scent chemistry of the acuri palm (Attalea phalerata), assessing its role in the attraction of flower-visiting insects associated with this species over its natural distribution range. We sampled insects from staminate inflorescences of A. phalerata (n = 6) at four different sites in the Brazilian Atlantic Forest and Cerrado, and Colombian Amazon basin. Dynamic headspace scent samples of both pistillate and staminate inflorescences of A. phalerata (n = 3♀, 3♂) were collected and analyzed by gas chromatography-mass spectrometry. Methyl acetate, a rare floral scent compound, was identified as the almost exclusive constituent (> 99.8% relative percentage) in all the samples. Flight-interception traps baited with methyl acetate, installed in one of the sites in the Brazilian Cerrado, were attractive to beetles associated with inflorescences of A. phalerata across all four sampling sites (9 spp. in total), including the putative main pollinators (Mystrops spp., Nitidulidae; Andranthobius spp., Curculionidae) and various palm borers (Paratenthras martinsi, Cerambycidae; Parisoschoenus sp.1 and Belopoeus sp.1; Curculionidae). Methyl acetate is highly volatile and we hypothesize its efficacy relies on profuse emission by the inflorescences of A. phalerata, as specialized pollinating insects respond to high concentrations of the attractant, perhaps before odor plumes rapidly disperse. Such a strategy could prove particularly effective in dense populations of A. phalerata.

Drivers of transgression: What pushes people to enter protected areas

The establishment of protected areas is central to biodiversity conservation strategies. However, they often fail in meeting their expectations, especially in the tropics. One core reason for their failure is human pressure. Protected area transgression has tremendous impacts on biodiversity, but also on persecuted rule-breakers whose necessities are often ignored. Despite the increasing enforcement of strict protection rules, non-compliance is a phenomenon experienced in protected areas around the world. To improve biodiversity and social outcomes of any conservation intervention, we need to understand what drives transgressive behavior but also the gazettement of protected areas. By using a role-playing game with Indigenous people in the Colombian Amazon we were able to openly discuss transgression. In the game, park managers designed protected areas primarily for biodiversity conservation but also for restoration. Communication among stakeholders and a resource-abundant landscape were key to increase compliance without exerting enforcement while the violations history of the protected area as well as the abundance of resources within its boundaries encouraged transgression. To achieve voluntary compliance, we recommend to acknowledge transgression's multidimensionality and integrate it into conservation planning.

Deciphering the introduction and transmission of SARS-CoV-2 in the Colombian Amazon Basin.

BackgroundThe SARS-CoV-2 pandemic has forced health authorities across the world to take important decisions to curtail its spread. Genomic epidemiology has emerged as a valuable tool to understand introductions and spread of the virus in a specific geographic location.Methodology/Principal findingsHere, we report the sequences of 59 SARS-CoV-2 samples from inhabitants of the Colombian Amazonas department. The viral genomes were distributed in two robust clusters within the distinct GISAID clades GH and G. Spatial-temporal analyses revealed two independent introductions of SARS-CoV-2 in the region, one around April 1, 2020 associated with a local transmission, and one around April 2, 2020 associated with other South American genomes (Uruguay and Brazil). We also identified ten lineages circulating in the Amazonas department including the P.1 variant of concern (VOC).Conclusions/SignificanceThis study represents the first genomic epidemiology investigation of SARS-CoV-2 in one of the territories with the highest report of indigenous communities of the country. Such findings are essential to decipher viral transmission, inform on global spread and to direct implementation of infection prevention and control measures for these vulnerable populations, especially, due to the recent circulation of one of the variants of concern (P.1) associated with major transmissibility and possible reinfections.

Efecto del pH sobre la concentración de nutrientes en cacao (Theobroma cacao L.) en la Amazonia Colombiana

La acidez del suelo limita la disponibilidad, la absorción y la concentración de nutrientes y el rendimiento del cultivo de cacao. El objetivo fue evaluar el efecto del pH del suelo sobre la concentración de nutrientes en hoja, cáscara y grano, para cuatro clones de cacao autocompatibles (ICS-1, CCN-51) y autoincompatibles (ICS-39, TSH-565), en el departamento del Caquetá. El diseño experimental consistió en un arreglo factorial con cuatro clones (factor A), cuatro niveles de pH y fertilidad (factor B) y cuatro repeticiones. Los resultados indican diferencias en la concentración de nutrientes por efecto del clon y tratamiento, siendo la acumulación de N, P y Mg en grano>hoja>cáscara, K en cáscara>hoja>grano, Ca, Fe, Mn, Zn y B en hoja>cáscara>grano, S en cáscara>hoja>grano y Cu en grano>cáscara>hoja. La concentración de P, Mg y S fue mayor y, a su vez, menor Mn, cuando aumentó el pH. El orden de extracción nutrimental en grano fue N>K>P>Mg>S>Ca>Fe>Mn>Zn>Cu>B. Con relación a los clones, CCN-51 presentó habilidad para la toma de nutrientes y alcanzar mayores producciones, incluso, en suelos con pH ≥ 5,5, lo que sugiere efecto de las condiciones edafoclimáticas y, por lo tanto, la necesidad de evaluar los clones para cada zona de cultivo.

Assessment of biodiversity goods for the sustainable development of the chagra in an indigenous community of the Colombian Amazon: local values of crops

BackgroundThe chagra is the agroforestry system adapted to the characteristics of the Amazon region. Recently, there has been a reported loss of biodiversity and traditional knowledge associated with the chagras. This paper characterizes the cultivators, exploring knowledge and expressed value perception in the context of the Amazonian chagra of an indigenous community; also, this prioritizes species, under the optics of commercial opportunity.MethodsA semi-structured instrument was applied to 14 volunteers, asking about marketing preferences and use values of the species; later, a floristic inventory and prioritization workshop was developed.ResultsSixty-two percent of the participants were 50 years or older at the time of the interview. Open conversations showed that traditional knowledge is a matter of practice; and is maintained mainly by the older "grandfathers". Thirty-eight species, belonging to 28 different families, were reported, showing considerable diversity. Seventy-nine percent of the participants consider the Leticia market and sales to tourists as the main marketing scenarios.ConclusionsThe Ziora-Amena community centralizes the handling of chagras in the community's older adults, who transmit their traditional knowledge to new generations through oral tradition. Indicators of preference, use, and abundance highlight the food species. The perception of the trade stakeholder encourages research and development of endemic species, with health properties or ingredients for industry, which represent an opportunity of high added value for the region.

Influence of nitrogen supply on gas exchange, chlorophyll fluorescence and grain yield of breeding lines of common bean evaluated in the Amazon region of Colombia

The common bean (Phaseolus vulgaris L.) is a food crop that provides fiber, vitamins and carbohydrates and it is produced by smallholders in developing countries under nitrogen (N)-depleted and low-fertility soil conditions. Soil acidity and the associated aluminum toxic and phosphorus deficient conditions are known to reduce symbiotic N-fixing ability of common bean. Breeding lines of common bean have been developed to adapt to acid-soil and high-temperature conditions in the Amazon region but the response of these lines to N application was not determined. The present study was conducted with an objective to identify genotypic differences among ten common bean breeding lines (4 Andean, 5 Mesoamerican, 1 interspecific) in their physiological characteristics (gas exchange, chlorophyll fluorescence and photosynthetic efficiency) and their contribution to superior agronomic performance under three different levels of N (0, 60 and 120 kg N ha−1; N0, N60 and N120) supply. We tested the hypothesis that common bean genotypes that combine greater capacity to assimilate carbon with improved ability to mobilize photosynthates to developing pods and seeds could enhance their agronomic performance at different levels of N supply under high-temperature and acid soil-stress conditions in the field. A randomized complete block design with factorial arrangement (3 levels of N × 10 genotypes) in three replications was used for the study. Measurements included photosynthetic gas exchange characteristics (light and CO2-saturated photosynthesis), chlorophyll fluorescence, viability of pollen, leaf N concentration, photosynthetic N use efficiency and grain yield. The increase in supply of N had a significant effect on grain yield and on different photosynthetic characteristics. Results showed that lines with indeterminate growth habit responded better to increase in N supply through their physiological response in improving grain yield. Among the genotypes evaluated, two lines (BFS 10 and SEF 10) were outstanding in their agronomic performance due to greater photosynthetic capacity combined with greater ability to mobilize photosynthates to grain with increase in N supply. These two lines can serve as parents for further improvement in resource use efficiency and multiple-stress resistance of common bean in the tropics.

Cacao agroforestry systems improve soil fertility: Comparison of soil properties between forest, cacao agroforestry systems, and pasture in the Colombian Amazon

The objective of our work was to evaluate soil quality in different cacao agroforestry systems (AFS) in the Colombian Amazon. We compared soil quality of AFS at the study site with soil quality of two control systems: a pasture and a secondary forest.The study was conducted at the Macagual Amazon Research Center in western Colombian Amazon. We set up eight 600 m² plots in each study system. We collected soil samples in each plot, and assessed macrofauna diversity, aggregate morphology, and physical and chemical soil properties. We integrated these variables in a General Indicator of Soil Quality (GISQ).We found GISQ values of 0.85 for forest, 0.5, 0.65 and 0.59 for AFS and 0.21 for pasture, and the values differed significantly between land uses. The establishment of cacao AFS on degraded pasture was found to significantly improve soil fertility, i.e., by 42%. The intensification level between land uses (Pasture > AFS > Forest) negatively affected macrofauna populations due to soil compaction (physical properties). Forest had the highest physical and biological quality.Our results show that AFS not only have the capacity to maintain key soil ecological functions, but also to restore soil quality of degraded pastureland. Cacao-based AFS could therefore be a key restoration strategy for degraded pastureland. These results are very important in the context of the Colombian Amazon, where cacao is currently known as the “crop of peace”.

First confirmed record of the LaVal’s Disk-winged Bat, Thyroptera lavali Pine, 1993 (Chiroptera, Thyropteridae), from Colombia

We document the first record of Laval’s Disk-winged Bat, Thyroptera lavali Pine, 1993, from the Amazon region of Colombia. This record increases to four the number of Thyroptera species in the country and extends the known range of T. lavali 428 km east and 338 km north from the nearest previous localities. The distribution of this species now comprises 11 localities from six ecoregions and five countries: Brazil, Colombia, Ecuador, Peru, and Venezuela. We highlight the paucity of knowledge on bat species in the Colombian Amazon.

Agroforestry systems in the Colombian Amazon improve the provision of soil ecosystem services

In the Colombian Amazon, the provision of soil-based ecosystem services is threatened mainly by loss of plant cover. Methodologies are required that allow for a holistic assessment of soil degradation or restoration and associated changes in the provision of ecosystem services. With this objective, we measured macroinvertebrate communities, soil macroaggregates, soil hydrological properties and chemical soil properties in areas of the deforested Colombian Amazon. The sampled areas are located two landscape units (undulating footslopes and hillsides) and four different land use types (Mature Forest, Forest Implementations, Sylvopastoral Systems and Traditional pastures). Parameters were assembled into soil hydrological, chemical soil properties, macroaggregates and macroinvertebrate communities sub indicators that were subsequently grouped into a General Indicator of Soil Quality (GISQ). Values indicated differences in the provision of soil-based ecosystem services among landscape units and land use types. We confirmed and quantified the negative effects of deforestation and land-use intensification, increasing from Forest Implementation to Sylvopastoral Systems and Traditional Pastures. Soil macroinvertebrate communities and physical properties as proxies for soil biodiversity and soil hydrological functions were the most negatively affected.