Colombian Andes Research Articles

Moisture Recycling in the Colombian Andes

AbstractThe Colombian Andes (CA) are located over the northwestern corner of tropical South America (NW‐TropSA), where land and atmosphere interchange moisture and energy in a complex way owing to the orographic influence on the recycling of moisture over land. We aim to understand where and when water vapor evaporated from land turns into rainfall through moisture recycling, using the Water Accounting Model‐2layers (WAM‐2), an offline model to track atmospheric moisture forced with data from ERA‐5 at its native 0.25° resolution during 1980–2020. We define the spatiotemporal distribution of sources (high evaporation recycle ratios, ϵC) and receptors (high precipitation recycle ratios, ρC) of continental moisture at diverse timescales, including monthly, seasonal, annual and interannual (ENSO). Referring to the regional runs of WAM‐2 over NW‐TropSA (4°S–12°N/80°W–66°W), at elevations above 1,000 m.a.s.l., the CA has a mean annual ρC of 11% (ranging 6%–16%) and a mean annual ϵC of 35% (ranging 27%–40%). Moisture recycling in the CA exhibits a strong annual cycle over the region. The seasonal dynamic of moisture recycling shows two clear‐cut sources of moisture: the eastern foothills of the Eastern and Central ranges of the CA. Both foothills are also regions of high rainfall, although moisture recycling mechanisms differ. Sources of continental moisture grow spatially during September‐October‐November and March‐April‐May. The seasonal availability of moisture recycled coincides with regions where orography interacts with low level jets sourcing humidity. At interannual timescales, sources and receptors of continental moisture in the CA are modulated by the extreme phases of ENSO.

Flexural behavior of composite section of multiple full-culm bamboo beams with mortar infill bolted joints

Full-culm bamboo has several characteristics that make it an excellent alternative construction material due to its rapid growth rate, high strength-to-weight ratio, and high carbon sequestration. Thus, it becomes crucial to study the mechanical and structural performance of bamboo within an engineering framework, such as flexural behavior of multi-culm elements, since it is a key issue of typical elements of building such beams, joists, and others. While there is a general understanding of the composite section behavior in materials such as timber, steel and concrete, there is a lack of experimental evidence concerning bamboo in this regard. Therefore, an experimental program was undertaken by the Center of Research in Materials and Civil Works (CIMOC) at the Universidad de Los Andes in Colombia. Two- and three-culm elements of Guadua angustifolia Kunth from a Colombian plantation using a Bolted-Mortar Infill connections were tested in a bending setup. The gamma method, extensively employed in timber standards, was used to find the percentage of composite section for different number of shear connectors. Montecarlo simulations were performed to deal with uncertainty of the modulus of elasticity and the slip modulus (stiffness) of the Bolted-Mortar Infill connection. Additionally, a design factor FI was proposed that allows to find the ratio of increment of the effective moment of inertia of partially composite section for different connection configuration. Equations were derived and proposed for C and FI through linear regression.

Mapping hydropower expansion and cash crop dynamics in Colombia using Landsat time series

Satellite-based monitoring provides insights on synergies and trade-offs between energy production and land use and land cover (LULC) changes (LULCC) around hydropower dams. Using Landsat data, we mapped LULCC related to hydropower expansion to understand change dynamics of cash crop production in the Magdalena River basin (Colombian Andes). We leveraged secondary map products and an active learning routine to produce thematically detailed LULC maps, for 2009, 2015, and 2020, including key cash crops (rice and oil palm). Our area-adjusted accuracy assessment revealed high overall and class-specific user’s and producer’s accuracies, exceeding 80% for oil palm, rice, non-agricultural vegetation, wetlands, and grasslands, and accuracies of ∼60% for other temporary and permanent crops. We identified substantial losses of rice (10,6%) and grasslands (25,9%) in El Quimbo due to reservoir flooding. For Hidrosogamoso, there was a loss of wetlands downstream. Our products provide the basis for balancing social, economic, and environmental trade-offs related to conflicting land uses.

Mineral chemistry and thermobarometry of Jurassic arc granitoids: implications for petrotectonic and unroofing history of the southern Colombian Andes

Abstract The Jurassic magmatic record in the southern Colombian (Northern Andes) includes numerous subduction-related I-type calc-alkaline granitoids with diverse structures and textures, formed in two main episodes at ∼195 to 165 Ma and ∼165 to 145 Ma. We provide new insights into the mineral chemistry, estimates of intensive parameters and petrogenetic processes of 12 plutonic occurrences in the region, grouped in 4 petrographic associations. Primary mineral assemblages include labradorite-to-oligoclase, alkali feldspars, ferroan enstatite, Mg-rich augite to ferroan-diopside, tschermakite to hastingsite and hornblende and Mg-rich annite; Fe-rich phlogopite and actinolite are post-magmatic phases. Amphibole chemistry indicates that the older (195–165 Ma) Jurassic bodies formed from relatively highly oxidized (fO2 values buffered at −0.1 ≤ NNO ≤ +1.4) hydrous (∼4 to 6 wt % H2O) magmas and their differentiation involves significant crustal assimilation and/or magma mixing, fractional crystallization and late-magmatic re-equilibration processes. In contrast, the younger (165–145 Ma) Jurassic intrusives, derived from subducted-modified mantle sources, record moderately lower oxidized hydrous conditions (fO2 values −0.7 to 0.8 ≤ NNO; ∼5 wt % H2O) with magma evolution mainly controlled by fractional crystallization and late-magmatic re-equilibration processes. Clinopyroxene-only, amphibole-only and amphibole-plagioclase thermobarometry estimations suggest that the Jurassic occurrences crystallized over variable temperature (647°C–1087°C) and pressure (0.7–6.3 kbar) conditions, corresponding to emplacement depths ranging from ∼15, ∼8 to 11, ∼5 to 7 and <4 km along the arc crustal column. The obtained data combined with time evolution allow the identification of exhumed and fragmented arc blocks in the Jurassic magmatic system and provide an essential link between the orogenic deformation event poorly constrained in the Northern Andes.

Evaluation of U-Net transfer learning model for semantic segmentation of landslides in the Colombian tropical mountain region

Landslides in tropical regions, like the Colombian Andean region, pose unique challenges due to factors such as intense rainfall, steep slopes, and complex terrains. Mapping historical and current landslide activity through inventory maps is essential in tropical mountainous regions. While satellite data is commonly used for mapping, it can be time-consuming and manual-intensive, limiting inventory availability. Deep Learning (DL) models, especially Convolutional Neural Networks (CNNs), have shown promise in remote sensing applications with High Resolution (HR) imagery, including landslide detection. Despite advancements, their use in this field is still relatively limited. This study assesses the effectiveness of U-Net model, for automated landslide detection using spectral data from optical satellite imagery (RGB bands), two DEM-derived geo-indices (slope and curvature), and two Synthetic Aperture Radar (SAR) layers (VV amplitude pre- and post-landslide event in May 2015) across three image models (3, 5, and 7 bands). Initially, data is combined into multiband images, and the model is trained in the “La Argelia” river basin in Colombia’s Pacific region. Subsequently, the model is tested in the “La Liboriana” river basin in the western Andean region. The landslide detection results within the inference area are validated by comparing them with the landslide inventory and segmentation results. The U-Net model demonstrates good performance (F1-score around 0.70) for landslide detection, as confirmed in various geographical settings. By utilizing DL models and combining high-resolution satellite imagery, topographical, and SAR data, a comprehensive space-time mapping of landslides can be achieved. This approach has the potential to greatly improve the accuracy and effectiveness of landslide mapping, offering a more holistic view of the temporal dynamics related to these natural hazards.

Lithospheric underthrusting beneath the northern Eastern Cordillera plateau, Colombian Andes: Insights from analyzing tomographic inversion using local earthquake travel time and gravity data

The northern Eastern Cordillera in the Colombian Andes is a wide (~200 km) high-elevation (>2.5 km) subduction-related asymmetric plateau. This plateau is currently subjected to shortening and magmatic addition, and yet the nature of the lowermost crust and its transition to the underlying mantle remains poorly constrained. To improve our knowledge about the structure of the deep crust beneath the EC plateau, we conducted a joint inversion of travel times of local earthquakes and gravity data. Gravity contributes to up to 0.5% in dVp and dVs with no affectation of the shape or location of the discussed anomalies. Along the latitudinal profile with the highest resolution (~5.7°N), two anomalies are identified at depths of 40–60 km beneath the plateau. A western low-velocity anomaly is interpreted as crustal material underthrust eastward beneath the northwestern EC. This process is triggering the abrupt change in topography between the adjacent low-elevation basin and the orogenic plateau. Additionally, a high-velocity anomaly beneath the eastern flank of the EC is likely related to mantle metasomatism and westward underthrusting of the foreland lithosphere. This metasomatism is either related to the interaction between mafic magmas and the uppermost mantle or silica enrichment that occurred during a past episode of flat subduction. Evidence for foreland underthrusting includes relocated earthquakes at 33–42 km depth within the thrust system between the EC and the foreland, along with increased shortening in the eastern part of the plateau, an increase in exhumation rates, the eastward migration of deformation towards the foreland, and dominated thick-skinned deformation in the upper crust of the foreland with an eastward vergence of thrusts and related folds. Furthermore, within the central part of the plateau, our results show low velocities between 30 and 40 km depth, consistent with previous constraints, suggesting magmatic underplating beneath the Paipa-Iza volcanic complex.

Petrogenesis and tectonic implications of the carboniferous El Carmen Pluton, central Colombian Andes: insights from whole-rock and mineral geochemistry, in situ zircon Lu–Hf isotopes and U–Pb geochronology

ABSTRACT During the initial stages of Pangea amalgamation in the Carboniferous period, the Rheic Ocean basin experienced subduction prompted by the convergence between Gondwana and Laurasia, culminating in the basin’s closure that preceded the paleocontinent collision. This tectonic episode promoted the Carboniferous (Mississippian and Pennsylvanian) tholeiitic to calc-alkaline magmatism, represented in the Colombian Andes through the tonalite and diorite-gabbro facies of the El Carmen Pluton. We investigate the two main facies (felsic and mafic facies) of the plutonic body, which crop out in the Central Cordillera of the Colombian Andes. U-Pb zircon crystallization ages are 326 ± 1 Ma for the mafic facies and 313 ± 1 Ma for the felsic facies. Positive ɛHf(i) isotopes ranging from +5.4 to +10.9 suggest mantle-derived magma with low crustal assimilation. The progressive increase in Eu anomaly (Eu × 0.64 to 1.15) and high LREE/HREE ratios underscore a continental magmatic arc formation in congruence with a subduction context. Thermobarometric analyses of mineral geochemistry across both facies reveal the magmatic emplacement at temperatures spanning 753–910°C, pressures between 3 and 4.65 kbar, and depths approximating 9–14 km. The simultaneous presence of two magmatic facies bearing tholeiitic and calc-alkaline characteristics, separated by ~13 Ma crystallization gap, infers a magmatic recharge episode. The results highlight a slightly thickened crust due to the arc maturity, or a transition from shallow-dipping to steep-angle subduction, consistent with tectonic slab-rollback mechanisms. The modest crustal thickening, indicative of low arc maturation between 326 and 313 Ma, is concomitant with the closure of the western part of the Rheic Ocean basin.

Assessing torrentiality in catchments of the tropical Andes: A morphometric approach

Torrential flows represent one of the most catastrophic natural hazards in the Andes, and Colombia is not an exception. We computed and analyzed ten morphometric indexes, classified by the catchment geometry and relief characteristics, for 149 torrential catchments across Colombian Andes three branches (Western, Central, and Eastern cordilleras). We divided the study area into six tectonic-stratigraphic regions, and employed statistical tests such as the Shapiro-Wilk and ANOVA One-Way Permutation tests to assess index distributions within each region. The ANOVA One-Way Permutation test results revealed significant differences in the distributions of form factor (p-value 0.048), mean gradient (p-value 0.009), relief ratio (p-value 0.003), Melton ratio (p-value 0.006), and hypsometric integral (p-value 0.000) indices among regions. Likewise, the pairwise comparison tests identified that the following regions are different between them for Melton ratio: Central Cordillera and Plateau Antioqueño (p-value 0.032), Garzón Massif and Plateau Antioqueño (p-value 0.015), Garzón Massif and Santander Massif (p-value 0.05), and Plateau Antioqueño and Western Cordillera (p-value 0.032); for relief ratio: Central Cordillera and Plateau Antioqueño (p-value 0.0219), Estern Cordillera and Plateau Antioqueño (p-value 0.0425), Garzón Massif and Plateau Antioqueño (p-value 0.0058), Plateau Antioqueño and Western Cordillera (p-value 0.053); for hypsometric integral: Central Cordillera and Western Cordillera (p-value 0.0004), Eastern Cordillera and Western Cordillera (p-value 0.0004), Garzón Massif and Western Cordillera (p-value 0.0004), Plateau Antioqueño and Western Cordillera (p-value 0.0161), and Santander Massif and Western Cordillera (p-value 0.002). Based on the findings we computed confidence intervals for the population median of the studied morphometric parameters according to the region employing a non-parametric bootstrapping method. The statistical analysis highlights the importance of the geological and geomorphological features in the morphometric indices analysis as part of the torrential flow susceptibility assessment.Applying our findings, we tested proposed thresholds in a case study of the Santander Massif (Eastern Cordillera of Colombia), focusing on the 2020 Piedecuesta Flow. In the study case, we demonstrated the relevance of identifying the feeder catchments where the morphometric indices would be calculated from, especially in areas where significant hydrologic changes occur. Volumetric concentration variations along the Piedecuesta Flow path highlight the need to prioritize the recognition of feeder catchments as an imperative part of the susceptibility assessment. Our approach enriches the knowledge base for identifying torrential-prone basins and has important implications for natural hazard management, aiming at mitigating the impact of torrential flows in the Andes.

Behavioral Modification of Leucauge mariana Induced by an Ichneumonid Spider-Parasitoid, Hymenoepimecis castilloi, in the Colombian Andes

Hymenoepimecis is a genus of Darwin wasps in the Polysphincta group of genera (Hymenoptera: Ichneumonidae: Pimplinae) known as ectoparasitoids of a broad spectrum of spiders. The parasitoid induces production of a web known as cocoon web, which provides shelter and support for the wasp pupa. In this study, we describe for the first time the interaction between Hymenoepimecis castilloi Pádua & Sääksjärvi (Hymenoptera: Ichneumonidae) and its host spider Leucauge mariana (Taczanowski) (Araneae: Tetragnathidae) in the Colombian Andes, provide new records of wasp genus distribution, and described the behavioral modifications induced in the spider. Web modifications occurred in the webs of both solitary and aggregated individuals. Adhesive spirals were lacking, and webs were connected to vegetation by multiple threads in all cocoon webs, which was not seen attached to webs of non-parasitized spiders. All parasitoid cocoons were observed hanging on a vertical line in the hub of the cocoon web. As previously described for other species, we believe that this modified web design results in increased web strength and favors parasitoid development during the pupal stage.

Historical perspective and state of knowledge of the nonavian reptiles (Vertebrata: Sauropsida) of the Department of Caldas, Central Andes of Colombia

Studying non-avian reptiles in the Colombian Andean region has encompassed various spatial scales and historical times. The knowledge of non-avian reptile diversity in the Department of Caldas (Central Andes; 7,888 sq. km. area; intricate geomorphology) has grown significantly in recent decades, especially in the areas to the east of the department within the Magdalena Valley and near Manizales, the capital city. Here, we consolidate the data from biological collections, literature, and unpublished research in a historical synopsis of the studies conducted in Caldas with an updated account of non-avian reptile species recorded in them. We found that the records of non-avian reptiles in Caldas trace back to pre-Columbian and colonial times, with specimens in biological collections dating back over a century. This non-avian reptile richness comprises 126 species grouped in 69 genera, 25 families, and three orders. Three out of the 27 municipalities in Caldas (La Merced, Marulanda, and Marquetalia) lack validated specimens or records. Furthermore, there is limited information regarding protected areas such as Los Nevados and Selva de Florencia National Natural Parks, which demands further research to unravel the diversity patterns of this biological group within this specific segment of the Andes.

Studies on Neotropical crickets: A new Perugryllae cricket (Orthoptera: Gryllidae: Gryllinae: Gryllini: Brachytrupina) from the foothills of the Colombian Andes.

A new tiny field cricket species of the genus Laureopsis (Orthoptera: Gryllidae), from the foothills of the Colombian Andes is described. With the description of Laureopsis andinus n. sp., the distribution of the Perugryllae Group expands outside the Amazon rainforest of Colombia and Peru, and is recorded for the first time in areas of Andean influence. A distribution map and a key for the identification of the species of the group are also provided. Finally, the morphology and distribution of the species of the two genera known for the Perugryllae group are discussed.

Improving estimates of land protection costs in a tropical biodiversity hotspot

Accurate estimates of the costs of land protection are useful for understanding where biodiversity conservation goals can be achieved at the lowest cost to society. However, because of the scarcity of high‐quality cost maps for tropical countries, conservation planning studies often ignore cost or rely on untested proxies, such as agricultural rent or land‐use intensity. Here, we show how analysts can estimate land protection costs using original data of public land acquisitions, global predictor datasets, and simple machine‐learning models. For the Colombian Andes, a global biodiversity hotspot, we found that the principal driver of the cost of land protection is urban proximity, not agricultural rent. We derived cost estimates that predict public land protection costs more accurately than available cost proxies and identified new protection priorities for 143 threatened bird species. A more systematic collection of cost records of land protection will help inform public decisions on national and global biodiversity protection priorities.

Variable thermal plasticity of leaf functional traits in Andean tropical montane forests.

Tropical montane forests (TMFs) are biodiversity hotspots and provide vital ecosystem services, but they are disproportionately vulnerable to climate warming. In the Andes, cold-affiliated species from high elevations are being displaced at the hot end of their thermal distributions by warm-affiliated species migrating upwards from lower elevations, leading to compositional shifts. Leaf functional traits are strong indicators of plant performance and at the community level have been shown to vary along elevation gradients, reflecting plant adaptations to different environmental niches. However, the plastic response of such traits to relatively rapid temperature change in Andean TMF species remains unknown. We used three common garden plantations within a thermosequence in the Colombian Andes to investigate the warming and cooling responses of key leaf functional traits in eight cold- and warm-affiliated species with variable thermal niches. Cold-affiliated species shifted their foliar nutrient concentrations when exposed to warming, while all other traits did not significantly change; contrastingly, warm-affiliated species were able to adjust structural, nutrient and water-use efficiency traits from acquisitive to conservative strategies in response to cooling. Our findings suggest that cold-affiliated species will struggle to acclimate functional traits to warming, conferring warm-affiliated species a competitive advantage under climate change.

Erosion rates and morphogenesis of the El Peñol de Guatapé inselberg, northern Andes (Colombia), inferred from geomorphic analyses and cosmogenic 10Be measurements

Inselbergs are isolated rock bodies that develop as a result of differential weathering and erosion advances during topographic etchplain formation. The timing and rate of inselberg growth are key for constraining external controls on landscape evolution, particularly in etching terrains associated with elevated plateaus carved on granitic lithologies, and in tectonically active provinces in tropical climate zones (e.g., Antioqueño Plateau, AP). We applied new morphostratigraphic and geomorphometric analyses, along with 10Be terrestrial cosmogenic nuclide (TCN) measurements, to in situ rock samples from the Peñol de Guatapé Inselberg (PGI), in the AP of the Colombian Andes to address the chronological framework of bornhardt formation in this tropical setting. The PGI is located in a rejuvenated landscape between middle Miocene to late Mio-Pliocene erosion surfaces. Erosion rates inferred from 10Be analyses ranged between ∼0.0024 ± 0.0001 and 0.24 ± 0.0283 mm/yr. This broad range is consistent with the long-term erosion rate of ∼0.04 mm/yr and mid-term erosion rates of 0.01–0.08 mm/yr previously documented for the region using low-temperature thermochronology. Our findings indicate that the PGI emerged as an important landscape feature over a period of ∼0.5–2.0 Myr and has protruded high above the average AP surface since the Pliocene. The new TCN-derived erosion-rate estimates for the AP Inselberg enable us to better understand the role of weathering and erosional processes that controlled the evolution of landscape surfaces during Andean orogenic cycles documented in the region.

Mechanisms Controlling the 4D Distribution of Rainfall and Latent Heating Over the Rainiest Region on Earth

AbstractGlobal Precipitation Measurement satellite and ERA5 reanalysis data are used to study the 4D (latitude, longitude, altitude, time) distribution of rainfall intensity and latent heating fields over the rainiest region on Earth, located over western Colombia and the far eastern equatorial Pacific. The annual and interannual variability and the location of both variables' maxima are identified, and their spatiotemporal correlations are quantified. Static analyses of the winds show that the colder Choco low‐level jet (LLJ) and the warmer Caribbean‐Panama jet form a tropical frontal system. Dynamic analyses of 3D streamlines reveal that the Choco LLJ is at the core of a quasi‐permanent mini‐Hadley cell over the Pacific, with sinking motion between 6°S‐Equator and rising motion at 5°N–8°N, comprised between 1,000 and 700 hPa. Such vortex dynamics enhances the convergence of the northerly winds and the Panama jet, and exacerbates deep convection in association with the orographic lifting over the Colombian Andes. The large‐scale branches of that flow illuminate the shape and dynamics of the Walker cell over tropical South America. Correlation analyses illustrate the connections between rainfall and 3D winds as moisture transport mechanisms. Correlation and singular value decomposition analyses suggest that oceanic (continental) evaporation is associated with rainfall during the drier (wetter) season, and the importance of high‐levels temperatures and vertical integrals of diverse thermal and energy variables on rainfall bolster the view that the condensational heating is strongly coupled with the moisture transport flow and the convective ascent required to explain such extraordinary amounts of rainfall.

Participatory mapping of local stakeholders’ perceptions of nature’s contributions to people in an intensified agricultural area in the Colombian Andes

ABSTRACT Intensification of agricultural land use in traditional Andean production landscapes has led to changes in the provision of nature’s contributions to people (NCP) that can threaten people’s wellbeing. Understanding local stakeholders’ valuation of these NCP is crucial for improving land use decisions. We implemented a spatially explicit and participatory NCP valuation method, using semi-structured interviews and participatory mapping, followed by a spatial multi-criteria decision analysis, to identify priority areas for NCP provision in a highly intensified production landscape in the Colombian Andes. We considered multiple value types, ecological, economical and sociocultural, and the points of view of different actors, orienting this towards decision-making on land use. Our results show that local actors can identify and value a wide range of NCP. However, there are also significant differences between actors. Environmentalists attached special importance to regulating NCP, while agricultural laborers focused more on agriculture-related material NCP. As we expected, tourism entrepreneurs especially valued non-material NCP related to their business experiences. Small-scale farmers tended to put more importance on regulating and non-material NCP than big farmers did. Although there was a consensus between actors as to the importance of natural ecosystems for NCP provision, agricultural actors tended to attach more importance to material NCP in areas deemed important for regulating and non-material NCP by other actors. Our main results confirm the importance of involving different stakeholders in spatial NCP valuation exercises, recognizing their different points of view to help identify possible trade-offs and synergies related to land use.

Two new Darwin wasp species of Eiphosoma Cresson, 1865 (Ichneumonidae: Cremastinae) from the northwestern Andes of Colombia.

Two new Darwin wasp species of Eiphosoma Cresson, 1865 (E. nigroandinum Fernandes sp. nov. and E. merceae Fernandes sp. nov.) are described from the northwestern Andes of Colombia. Furthermore, we propose the establishment of a new species-group, E. nigroandinum species-group, to encompass these newly described species. Additionally, we expand the geographical distribution of Eiphosoma vitticolle Cresson, 1865, and complement the findings with a map and digital images.

Two New Species of Small-Eared Shrews of the Genus Cryptotis Pomel, 1848, from the Colombian Andes (Mammalia: Eulipotyphla: Soricidae)

Two New Species of Small-Eared Shrews of the Genus Cryptotis Pomel, 1848, from the Colombian Andes (Mammalia: Eulipotyphla: Soricidae)

Soil erosion due to rainfall and the impacts of climate change in an Andean highland in Colombia

Trends and median slope of daily rainfall that can affect rainfall aggressiveness and cause erosion in the Bogotá - Duitama corridor were studied. For this, the daily records of 26 stations (35 years, from 1980 to 2014) were evaluated, using the Sen's statistic and the Mann-Kendall test with confidence levels higher than 90%. The studied area covered about 8,100 km2, located between 2,100 and 3,300 m a.s.l. in the Colombian Andes. Four stations with positive trends in median annual rainfall were found (from 6.90 mm/year to 28.80 mm/year) and one station with a decrease in median rainfall of -6.86 mm/year. In order to analyze the pluvial aggressiveness as the main agent of soil erosion, the Modified Fournier Indices (MFI) were generated for periods of 10 days. With the maximum decadal Modified Fournier Indices (MFIdmax) of each year, it was possible to establish the median positive trend (Sen) of rainfall aggressiveness in five stations and three stations with negative trends. Through the correlation between the degree of erosion with the square of the decadal average maximum values of each year (MFIdmax2) and the negative annual precipitation, a coefficient of determination (R2) greater than 0.50 was found. The validation of MFIdmax2 to explain the degree of soil erosion is a new useful methodology for land use planning and monitoring. In this way, developing countries have the possibility of using a tool to face the processes of pluvial erosion, vulnerability and adaptation to climate change.

Two new species of Lepidocyrtus (Fractocyrtus) Cipola & Bellini (Collembola, Entomobryidae, Lepidocyrtinae), with new records and a new name for Lepidocyrtus (F.) americanus Cipola & Bellini, 2018.

Herein we propose a new name, Lepidocyrtus (Fractocyrtus) amazonaensis nom. nov. Cipola, to replace L. americanus Cipola & Bellini 2018, a combination preoccupied by Marlatt (1896). In addition to new geographic records for the species, two new species of Fractocyrtus are described: L. (Fractocyrtus) andensis sp. nov. from the Colombian Andes and L. (Fractocyrtus) chicomendesi sp. nov. from the Occidental Brazilian Amazon. The new species differs from other members of the subgenus in body color, dorsal chaetotaxy of the head, chaetotaxy of the third and fourth abdominal segment, postlabial chaetotaxy, trochanteral organ, collophore and furcula, beyond morphology on the lateral process of the labial papilla E. New patterns of body pseudopores are described and added to the new diagnosis for the subgenus. Fractocyrtus now has four species, with distribution from the Andes to the Oriental Brazilian Amazon.