Andes Of Southern Ecuador Research Articles

New insight on the recent tectonic evolution and uplift of the southern Ecuadorian Andes from gravity and structural analysis of the Neogene-Quaternary intramontane basins

The sedimentary basins of Loja, Malacatos-Vilcabamba and Catamayo belong to the Neogene-Quaternary synorogenic intramontane basins of South Ecuador. They were formed during uplift of the Andes since Middle-Late Miocene as a result of the Nazca plate subduction beneath the South American continental margin. This E-W compressional tectonic event allowed for the development of NNE-SSW oriented folds and faults, determining the pattern and thickness of sedimentary infill. New gravity measurements in the sedimentary basins indicate negative Bouguer anomalies reaching up to −292 mGal related to thick continental crust and sedimentary infill. 2D gravity models along profiles orthogonal to N-S elongated basins determine their deep structure. Loja Basin is asymmetrical, with a thickness of sedimentary infill reaching more than 1200 m in the eastern part, which coincides with a zone of most intense compressive deformation. The tectonic structures include N-S, NW-SE and NE-SW oriented folds and associated east-facing reverse faults. The presence of liquefaction structures strongly suggests the occurrence of large earthquakes just after the sedimentation. The basin of Malacatos-Vilcabamba has some folds with N-S orientation. However, both Catamayo and Malacatos-Vilcabamba basins are essentially dominated by N-S to NW-SE normal faults, producing a strong asymmetry in the Catamayo Basin area. The initial stages of compression developed folds, reverse faults and the relief uplift determining the high altitude of the Loja Basin. As a consequence of the crustal thickening and in association with the dismantling of the top of the Andes Cordillera, extensional events favored the development of normal faults that mainly affect the basins of Catamayo and Malacatos-Vilcabamba. Gravity research helps to constrain the geometry of the Neogene-Quaternary sedimentary infill, shedding some light on its relationship with tectonic events and geodynamic processes during intramontane basin development.

Effects of hummingbird morphology on specialization in pollination networks vary with resource availability

Specialization of species in interaction networks influences network stability and ecosystem functioning. Spatial and temporal variation in resource availability may provide insight into how ecological factors, such as resource abundance, and evolutionary factors, such as phylogenetically conserved morphological traits, influence specialization within mutualistic networks. We used independent measures of hummingbird abundance and resources (nectar), information on hummingbird traits and plant–hummingbird interactions to examine how resource availability and species' morphology influence the specialization of hummingbirds in three habitat types (forest, shrubs, cattle ranch) sampled over 10 sessions across two years in the southern Andes of Ecuador. Specialization of hummingbird species in the networks was measured by three indices: d' (related to niche partitioning), generality (related to niche width) and PSI (related to pollination services). Specialization indices d', generality and PSI of hummingbird species were influenced by resource availability. All indices indicated that specialization of hummingbirds increased when the availability of resources decreased. Variation in d' was also explained by an interaction between resource availability and bill length; hummingbirds with a long bill switched from being more specialized than other species when resource availability was low to being similarly specialized when availability was high. Overall, our results highlight the importance of ecological and evolutionary factors determining the specialization of species in interaction networks. We demonstrate in particular that ecological gradients in resource availability cause substantial changes in consumers' foraging behavior contingent on their morphology. Changes in pollinator specialization along resource gradients can have impacts on ecosystem functions, such as pollination by animals.

Turning Up the Heat on a Hotspot: DNA Barcodes Reveal 80% More Species of Geometrid Moths along an Andean Elevational Gradient.

We sampled 14,603 geometrid moths along a forested elevational gradient from 1020–3021 m in the southern Ecuadorian Andes, and then employed DNA barcoding to refine decisions on species boundaries initially made by morphology. We compared the results with those from an earlier study on the same but slightly shorter gradient that relied solely on morphological criteria to discriminate species. The present analysis revealed 1857 putative species, an 80% increase in species richness from the earlier study that detected only 1010 species. Measures of species richness and diversity that are less dependent on sample size were more than twice as high as in the earlier study, even when analysis was restricted to an identical elevational range. The estimated total number of geometrid species (new dataset) in the sampled area is 2350. Species richness at single sites was 32–43% higher, and the beta diversity component rose by 43–51%. These impacts of DNA barcoding on measures of richness reflect its capacity to reveal cryptic species that were overlooked in the first study. The overall results confirmed unique diversity patterns reported in the first investigation. Species diversity was uniformly high along the gradient, declining only slightly above 2800 m. Species turnover also showed little variation along the gradient, reinforcing the lack of evidence for discrete faunal zones. By confirming these major biodiversity patterns, the present study establishes that incomplete species delineation does not necessarily conceal trends of biodiversity along ecological gradients, but it impedes determination of the true magnitude of diversity and species turnover.

Developing an integrated framework to assess agri-food systems and its application in the Ecuadorian Andes

Agri-food systems assessment can be performed following official and alternative framings, each linked to different objects of study, methods of analysis, and policy responses. Alternative frames conceptualize agri-food systems as the integration and interaction of humans and the agro-environment (i.e., as socio-ecological systems). This conceptualization allows studying the cross-level, cross-scale, and nonlinear interactions within and between the components of the system and help assess policy proposals, such as food sovereignty, in a more systemic way. To facilitate this, we link reflections and methodologies from complex system thinking and vulnerability studies applied to agri-food systems to propose an integrated framework of assessment, which links the agroecological context and the social function of agriculture, considering actor’s agency and institutional processes. This framework is suitable to analyze agri-food systems in fragile and marginal environments such as the Andean region. We apply the framework to assess vulnerability of local agri-food systems to global change in the southern Ecuadorian Andes, taking into account the role of peasant institutions (agroecological associations, comunas) and indigenous culture. The framework also allows understanding how agri-food policies change the configuration of agri-food systems and determines whether these changes are consistent with communities’ livelihoods reproduction.

Late ninth millennium B.P. use of Zea mays L. at Cubilán area, highland Ecuador, revealed by ancient starches

Today, maize is acknowledged as a plant with a great culinary and industrial versatility. It also has a deep relationship with the native cultures of the Americas and is still a vital food source for hundreds millions of people worldwide. By means of starch grain extraction from ancient lithic artifacts used more than 8000 years ago, here we report what is so far the oldest documented occurrence of maize in highland South America. This study places maize, together with other important economic plants, in the southern Ecuadorian Andes during a period coinciding with the initial stage of maize diversification and long distance expansion after its domestication in southwestern Mexico. These results allow us to unravel an early episode of human innovation previously unknown for South America which is related to the first steps toward the full re-shaping of human subsistence strategies in the continent.

Two new species of Leptanilloides Mann, 1823 (Formicidae: Dorylinae) from the Andes of southern Ecuador

Two new species of Leptanilloides are described: L. copalinga Delsinne & Donoso sp. nov., and L. prometea Delsinne & Donoso sp. nov., based on workers collected in the leaf litter and soil of the Andes of southern Ecuador. Both species belong to the L. biconstricta species-group (formally diagnosed here). The metatibial gland, considered a synapomorphy for Dorylinae, is observed in L. prometea sp. nov. but seems absent in L. copalinga sp. nov. We provide a COI DNA barcode for both species and a revised key for the worker caste of all known species in the genus. We also describe a single male identified as a potential new Leptanilloides species on the basis of morphology. Furthermore, its mitochondrial COI gene sequence does not match any previously barcoded species. However, we refrain from giving it a specific name because of our lack of knowledge about the worker caste. So far, half of the 14 Leptanilloides species have been discovered above 1500 m in the mountain forests or páramos of the Ecuadorian Andes, confirming, if needed, the biological significance of these threatened habitats.

Senecio eliseae (Compositae, Senecioneae), a new species from the southern Ecuadorian Andes

Senecio eliseae is described as a new species from the southern Ecuadorian Andes. It is a suffrutescent herb characterized by erect branches that are leaved only in the upper half, yellow discoid nodding capitula, and glandular-hirsute indumentum on the stem, leaves, and synflorescence. Detailed photographs of plants from the type locality are provided.

Evaluation of the Penman-Monteith (FAO 56 PM) Method for Calculating Reference Evapotranspiration Using Limited Data

Reference evapotranspiration (ETo) is often calculated using the Penman-Monteith (FAO 56 PM; Allen et al 1998) method, which requires data on temperature, relative humidity, wind speed, and solar radiation. But in high-mountain environments, such as the Andean paramo, meteorological monitoring is limited and high-quality data are scarce. Therefore, the FAO 56 PM equation can be applied only through the use of an alternative method suggested by the same authors that substitutes estimates for missing data. This study evaluated whether the FAO 56 PM method for estimating missing data can be effectively used for paramo landscapes in the high Andes of southern Ecuador. Our investigation was based on data from 2 automatic weather stations at elevations of 3780 m and 3979 m. We found that using estimated wind speed data has no major effect on calculated ETo but that if solar radiation data are estimated, ETo calculations may be erroneous by as much as 24%; if relative humidity data are estimated, the error may b...

Microbial community structure and resource availability drive the catalytic efficiency of soil enzymes under land-use change conditions

The turnover of nutrients bound to organic matter is largely mediated by extracellular hydrolytic enzymes (EHEs) produced by soil microorganisms. However, little is known about the environmental drivers (e.g., soil pH, C content, C:N ratio) of the catalytic properties of EHEs and their functional link to the structure of soil microbial communities. We linked catalytic properties, Km and Vmax, determined by Michaelis–Menten kinetics, to a set of environmental and microbial properties in the soils of a land-use sequence ranging from undisturbed natural forest to pastures of different ages and to secondary succession in the Andes of southern Ecuador. The sensitivity of the substrate affinity constant (Km) and the maximum rate (Vmax) of six EHEs (β-cellobiohydrolase (CBH), β-glucosidase (BG), N-acetylglucosaminidase (NAG), α-glucosidase (AG), xylanase (XYL), acid phosphomonoesterase (AP)) to changing environmental conditions was tested by fluorogenic substrates. We used the Vmax-to-Km ratio (Ka) as a proxy for the catalytic efficiency and the signature membrane phospholipid fatty acids as a proxy of microbial community structure.Microbial communities adapted to environmental changes, selected for enzymes with higher substrate affinity (Km) and catalytic efficiency (Ka) compared with pure cultures. Along the land-use sequence, catalytic efficiency increased from natural forest to young pasture, while it decreased during long-term pasture use and secondary succession. This is consistent with three to five times faster turnover of tested substrates (estimated based on Michaelis–Menten kinetic parameters) at the young pasture compared with the long-term pasture and secondary succession. Environmental drivers of the Km were enzyme-specific (e.g., the pH for XYL, the C:N ratio for AP, and the C availability for NAG) and differed from those for Vmax. A decoupled response of Vmax and Km to land-use changes observed for AG, BG, CBH, XYL, and AP, implies divers consequences for ecosystem processes mediated by these enzymes. A high abundance of Gram(−) bacteria triggered the catalytic properties (Km and/or Ka) of enzymes decomposing cellulose, hemicellulose, starch, and monophosphoesters. The importance of climatic factors for catalytic properties of EHEs was emphasized by the Ka values extracted from the literature and demonstrated good correspondence of Ka between soils from geographically distinct experimental plots.

Three new species of woodlizards (Hoplocercinae, Enyalioides) from northwestern South America.

The discovery of three new species of Enyalioides from the tropical Andes in Ecuador and northern Peru is reported. Enyalioides altotambo sp. n. occurs in northwestern Ecuador and differs from other species of Enyalioides in having dorsal scales that are both smooth and homogeneous in size, a brown iris, and in lacking enlarged, circular and keeled scales on the flanks. Enyalioides anisolepis sp. n. occurs on the Amazonian slopes of the Andes in southern Ecuador and northern Peru and can be distinguished from other species of Enyalioides by its scattered, projecting large scales on the dorsum, flanks, and hind limbs, as well as a well-developed vertebral crest, with the vertebrals on the neck at least three times higher than those between the hind limbs. Enyalioides sophiarothschildae sp. n. is from the Amazonian slopes of the Cordillera Central in northeastern Peru; it differs from other species of Enyalioides in having caudal scales that are relatively homogeneous in size on each caudal segment, a white gular region with a black medial patch and several turquoise scales in males, as well as immaculate white labials and chin. A molecular phylogenetic tree of 18 species of hoplocercines is presented, including the three species described in this paper and Enyalioides cofanorum, as well as an updated identification key for species of Hoplocercinae.

Regionalization of wind-speed data to analyse tree-line wind conditions in the eastern Andes of southern Ecuador

Regionalization of wind-speed data to analyse tree-line wind conditions in the eastern Andes of southern Ecuador

Land Cover Change in the Andes of Southern Ecuador—Patterns and Drivers

In the megadiverse tropical mountain forest in the Andes of southern Ecuador, a global biodiversity hotspot, the use of fire to clear land for cattle ranching is leading to the invasion of an aggressive weed, the bracken fern, which is threatening diversity and the provisioning of ecosystem services. To find sustainable land use options adapted to the local situation, a profound knowledge of the long-term spatiotemporal patterns of land cover change and its drivers is necessary, but hitherto lacking. The complex topography and the high cloud frequency make the use of remote sensing in this area a challenge. To deal with these conditions, we pursued specific pre-processing steps before classifying five Landsat scenes from 1975 to 2001. Then, we quantified land cover changes and habitat fragmentation, and we investigated landscape changes in relation to key spatial elements (altitude, slope, and distance from roads). Good classification results were obtained with overall accuracies ranging from 94.5% to 98.5% and Kappa statistics between 0.75 and 0.98. Forest was strongly fragmented due to the rapid expansion of the arable frontier and the even more rapid invasion by bracken. Unexpectedly, more bracken-infested areas were converted to pastures than vice versa, a practice that could alleviate pressure on forests if promoted. Road proximity was the most important spatial element determining forest loss, while for bracken the altitudinal range conditioned the degree of invasion in deforested areas. The annual deforestation rate changed notably between periods: ~1.5% from 1975 to 1987, ~0.8% from 1987 to 2000, and finally a very high rate of ~7.5% between 2000 and 2001. We explained these inconstant rates through some specific interrelated local and national political and socioeconomic drivers, namely land use policies, credit and tenure incentives, demography, and in particular, a severe national economic and bank crisis.

Landslide susceptibility near highways is increased by 1 order of magnitude in the Andes of southern Ecuador, Loja province

Abstract. Mountain roads in developing countries are known to increase landslide occurrence due to often inadequate drainage systems and mechanical destabilization of hillslopes by undercutting and overloading. This study empirically investigates landslide initiation frequency along two paved interurban highways in the tropical Andes of southern Ecuador across different climatic regimes. Generalized additive models (GAM) and generalized linear models (GLM) were used to analyze the relationship between mapped landslide initiation points and distance to highway while accounting for topographic, climatic, and geological predictors as possible confounders. A spatial block bootstrap was used to obtain nonparametric confidence intervals for the odds ratio of landslide occurrence near the highways (25 m distance) compared to a 200 m distance. The estimated odds ratio was 18–21, with lower 95% confidence bounds >13 in all analyses. Spatial bootstrap estimation using the GAM supports the higher odds ratio estimate of 21.2 (95% confidence interval: 15.5–25.3). The highway-related effects were observed to fade at about 150 m distance. Road effects appear to be enhanced in geological units characterized by Holocene gravels and Laramide andesite/basalt. Overall, landslide susceptibility was found to be more than 1 order of magnitude higher in close proximity to paved interurban highways in the Andes of southern Ecuador.

Host Plant Associations and Parasitism of South Ecuadorian Eois Species (Lepidoptera: Geometridae) Feeding on Peperomia (Piperaceae).

The very species-rich tropical moth genus Eois Hübner (Lepidoptera: Geometridae) is a promising model group for studying host plant specialization and adaptive radiation. While most Eois species are assumed to be specialized herbivores on Piper L. species, records on other plant taxa such as Peperomia Ruiz & Pavón (Piperaceae) are still relatively scarce. Moreover, little is known about life history traits of most species, and only a few caterpillars have been described so far. We collected caterpillars associated with Peperomia (Piperaceae) host plants from June 2012 to January 2013 in three elevational bands of montane and elfin rainforests on the eastern slopes of the Andes in southern Ecuador. Caterpillars were systematically searched and reared to the adult stage. We were able to delimitate ten species of Eois on Peperomia by comparison of larval and adult morphology and by using 658 bp fragments of the mitochondrial COI gene (barcode sequences). Three of these species, Eois albosignata (Dognin), Eois bolana (Dognin), and Eois chasca (Dognin), are validly described whereas the other seven taxa represent interim morphospecies, recognized unequivocally by their DNA barcodes, and their larval and adult morphology. We provide information about their host plants, degree of parasitism, and describe the larval stages in their last instar. Additionally, caterpillars and moths are illustrated in color plates. This is the first comparative study dealing with Eois moths whose caterpillars feed on Peperomia hosts.

Deforestation and benthic indicators: how much vegetation cover is needed to sustain healthy Andean streams?

Deforestation in the tropical Andes is affecting ecological conditions of streams, and determination of how much forest should be retained is a pressing task for conservation, restoration and management strategies. We calculated and analyzed eight benthic metrics (structural, compositional and water quality indices) and a physical-chemical composite index with gradients of vegetation cover to assess the effects of deforestation on macroinvertebrate communities and water quality of 23 streams in southern Ecuadorian Andes. Using a geographical information system (GIS), we quantified vegetation cover at three spatial scales: the entire catchment, the riparian buffer of 30 m width extending the entire stream length, and the local scale defined for a stream reach of 100 m in length and similar buffer width. Macroinvertebrate and water quality metrics had the strongest relationships with vegetation cover at catchment and riparian scales, while vegetation cover did not show any association with the macroinvertebrate metrics at local scale. At catchment scale, the water quality metrics indicate that ecological condition of Andean streams is good when vegetation cover is over 70%. Further, macroinvertebrate community assemblages were more diverse and related in catchments largely covered by native vegetation (>70%). Our results suggest that retaining an important quantity of native vegetation cover within the catchments and a linkage between headwater and riparian forests help to maintain and improve stream biodiversity and water quality in Andean streams affected by deforestation. This research proposes that a strong regulation focused to the management of riparian buffers can be successful when decision making is addressed to conservation/restoration of Andean catchments.

Catchment precipitation processes in the San Francisco valley in southern Ecuador: combined approach using high-resolution radar images and in situ observations

The precise estimation of precipitation quantities in tropical mountain regions is in great demand by ecological and hydrological studies, due to the heterogeneity of the rainfall distribution and the lack of meteorological station data. This study uses radar images and ground station data to provide the required high-resolution precipitation maps. Also wind data are taken into account, due to its influence on the precipitation formation and to demonstrate the relation between synoptic wind, topography and the precipitation distribution inside small mountain valleys. The study analyses the rainfall distribution and amounts of 4 days inside the San Francisco Valley, a small catchment in the tropical Andes of southern Ecuador, representing different seasons and the typical atmospheric flows, which are correlated to the annual precipitation map. The results show that the rainfall distribution and amounts are generally defined by the wind direction and velocity, besides the topographic location in relation to the main barriers and pathways. The dominant wind direction causes a division of the catchment in a wetter eastern and a dryer western part. Moreover, the annual seasons are reversed; the main rainy season for the eastern part occurs between June and August, while the western part reaches the precipitation maximum between January and March. This may have influence on the species composition at the different slopes and the annual hydrological cycle inside the catchment.

A new Andean species of Philodryas (Dipsadidae, Xenodontinae) from Ecuador.

We describe a new species of Philodryas from the highlands of southern Ecuador. The new species is distinguished from all known species of Philodryas by a unique combination of coloration, scalation, and hemipenial characters. The new species resembles Philodryas simonsii in color pattern. However, they differ notoriously by their hemipenial morphology. The three other trans-Andean members of the genus (Philodryas simonsii, Philodryas chamissonis, and Philodryas tachymenoides), along with the new species, compose a probably monophyletic group that may be characterized by the presence of ungrooved postdiastemal teeth in the maxilla. Unlike most species of the genus Philodryas, the new species shows a restricted distribution, being apparently endemic to a small region of high-altitude (3150-4450m) grasslands in the southern Andes of Ecuador.

Soil nutrient stock dynamics and land-use management of annuals, perennials and pastures after slash-and-burn in the Southern Ecuadorian Andes

Quantification of nutrient stocks and their temporal changes are considered of prime importance in farming systems of the humid tropics to answer the question of sustainable management. The research area in the Southern Ecuadorian Andes included forest, annual (0–5 years old) and different aged perennial (0–5, 6–10, 11–20, 21–30) and pasture (0–5, 6–10, 11–20, 21–30, >30) sites. Soil organic carbon (SOC), total and plant available soil nutrient stocks and nutrient balances were investigated to assess temporal soil nutrient dynamics in relation to management activities. Forest conversion by slash-and-burn caused a decrease in SOC stocks in all three land-uses amounting between 14% and 19%. This was mainly due to the absence of an organic layer and losses in the upper five cm of the mineral soil. Stocks of exchangeable bases and pH values increased in annuals which however, had the most negative nutrient balance of all land-uses amounting to −128, −25 and −226kgha−1a−1 for N, P and K, respectively. The abandonment of annual sites after five years was linked to a shortage of available N and P due to low-external-input management which caused SOC stock decreases. Major soil nutrient changes in perennials and pastures did not occur directly but 6–20 years after forest conversion with increases in stocks for total N, P, S and exchangeable bases above forest level. SOC stocks of medium aged perennials and pastures increased above forest level in the mineral soil. Easily available inorganic N and P stocks remained low throughout the chronosequence in perennials and pastures, indicating a quick uptake by plant roots and microorganisms. Compared to medium aged sites, oldest perennials and pastures showed a strong decrease in SOC (−28% and −16%) and soil nutrient stocks. Stocks for total N, P, S and exchangeable bases were up to 50% below those of medium aged sites in oldest perennials and pastures.

The Sloping Mire Soil-Landscape of Southern Ecuador: Influence of Predictor Resolution and Model Tuning on Random Forest Predictions

The sloping mire landscape of the investigation area, in the southern Andes of Ecuador, is dominated by stagnic soils with thick organic layers. The recursive partitioning algorithm Random Forest was used to predict the spatial water stagnation pattern and the thickness of the organic layer from terrain attributes. Terrain smoothing from 10 to 30 m raster resolution was applied in order to obtain the best possible model. For the same purpose, several model tuning parameters were tested and a prepredictor selection with the R-package Boruta was applied. Model versions were evaluated and compared by 100 repetitions of the calculation of the residual mean square error of a five-fold cross-validation. Position specific density functions of the predicted soil parameters were then used to display prediction uncertainty. Prepredictor selection and tuning of the Random Forest algorithm in some cases resulted in an improved model performance. We therefore recommend testing prepredictor selection and tuning to make sure that the best possible model is chosen. This needs particular emphasis in complex tropical mountain soil-landscapes which provide a real challenge to any soil mapping approach but where Random Forest has proven to be successful due to the testing of model tuning and prepredictor selection.

Influence of Patch Factors and Connectivity on the Avifauna of Fragmented Polylepis Forest in the Ecuadorian Andes

AbstractHuman‐induced alteration of habitat is a major threat to biodiversity worldwide, especially in areas of high biological diversity and endemism. Polylepis (Rosaceae) forest, a unique forest habitat in the high Andes of South America, presently occurs as small and isolated patches in grassland dominated landscapes. We examine how the avian community is likely influenced by patch characteristics (i.e., area, plant species composition) and connectivity in a landscape composed of patches of Polylepis forest surrounded by páramo grasslands in Cajas National Park in the Andes of southern Ecuador. We used generalized linear mixed models and an information‐theoretic approach to identify the most important variables probably influencing birds inhabiting 26 forest patches. Our results indicated that species richness was associated with area of a patch and floristic composition, particularly the presence of Gynoxys (Asteraceae). However, connectivity of patches probably influenced the abundance of forest and generalists species. Elsewhere, it has been proposed that effective management plans for birds using Polylepis should promote the conservation of mature Polylepis patches. Our results not only suggest this but also show that there are additional factors, such as the presence of Gynoxys plants, which will probably play a role in conservation of birds. More generally, these findings show that while easily measured attributes of the patch and landscape may provide some insights into what influences patch use by birds, knowledge of other factors, such as plant species composition, is essential for better understanding the distribution of birds in fragmented landscapes.