Publikationen
Es wurden 43 Publikationen gefunden
Wurz, A.; Bendix, J.; Homeier, J.; Matt, F.; Paladines, P.; Serrano, F. & Farwig, N. (2023): A hidden gem in the Tumbesian dry forest in southern Ecuador: Estacon Cientfica Laipuna. ECOTROPICA 25(1/2), -.
Raffelsbauer, V.; Pucha-Cofrep, F.; Strobl, S.; Knuesting, J.; Schorsch, M.; Trachte, K.; Scheibe, R.; Bräuning, A.; Windhorst, D.; Bendix, J.; Silva, B. & Beck, E. (2023): Trees with anisohydric behavior as main drivers of nocturnal evapotranspiration in a tropical mountain rainforest. PLOS ONE 18(3), 1-21.
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DOI: 10.1371/journal.pone.0282397
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Abstract:
Abstract:
This study addresses transpiration in a tropical evergreen mountain forest in the Ecuadorian Andes from the leaf to the stand level, with emphasis on nocturnal plant-water relations. The stand level: Evapotranspiration (ET) measured over 12 months with the Eddy-Covariance (ECov) technique proved as the major share (79%) of water received from precipitation. Irrespective of the humid climate, the vegetation transpired day and night. On average, 15.3% of the total daily ET were due to nocturnal transpiration. Short spells of drought increased daily ET, mainly by enhanced nighttime transpiration. Following leaf transpiration rather than air temperature and atmospheric water vapor deficit, ET showed its maximum already in the morning hours. The tree level: Due to the humid climate, the total water consumption of trees was generally low. Nevertheless, xylem sap flux measurements separated the investigated tree species into a group showing relatively high and another one with low sap flux rates. The leaf level: Transpiration rates of Tapirira guianensis, a member of the high-flux-rate group, were more than twice those of Ocotea aciphylla, a representative of the group showing low sap flux rates. Representatives of the Tapirira group operated at a relatively high leaf water potential but with a considerable diurnal amplitude, while the leaves of the Ocotea group showed low water potential and small diurnal fluctuations. Overall, the Tapirira group performed anisohydrically and the Ocotea group isohydrically. Grouping of the tree species by their water relations complied with the extents of the diurnal stem circumference fluctuations. Nighttime transpiration and hydrological type: In contrast to the isohydrically performing trees of the Ocotea group, the anisohydric trees showed considerable water vapour pressure deficit (VPD)-dependent nocturnal transpiration. Therefore, we conclude that nighttime ET at the forest level is mainly sourced by the tree species with anisohydric performance.
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Keywords: |
Ecuador |
Mountain forest |
evapotranspiration |
Trees |
Berdugo Moreno, M.B.; Heyer, L.; Contento, K.Y.S.; Déleg, J.; Bendix, J. & Bader, M. (2022): High-resolution tropical rain-forest canopy climate data. Environmental Data Science 1, e13.
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DOI: 10.1017/eds.2022.12
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Abstract:
Abstract:
Canopy habitats challenge researchers with their intrinsically difficult access. The current scarcity of climatic data from forest canopies limits our understanding of the conditions and environmental variability of these diverse and dynamic habitats. We present 307 days of climate records collected between 2019 and 2020 in the tropical rainforest canopy of the Yasuní National Park, Ecuador. We monitored climate with a 10-min temporal resolution in the middle crowns of eight canopy trees. The distance between canopy climate stations ranged from 700 m to 10 km. Apart from air temperature, relative humidity, leaf wetness, and photosynthetically active radiation (PAR), measured in each canopy climate station, global radiation, rainfall, and wind speed were measured in different subsets of them. We processed the eight data series to omit erroneous records resulting from sensor failures or lack of the solar-based power supply. In addition to the eight original data series, we present three derived data series, two aggregating canopy climate for valleys or for ridges (from four stations each), and one overall average (from the eight stations). This last derived data series contains 306 days, while the shortest of the original data series covers 22 days and the longest 296 days. In addition to the data, two open-source tools, developed in RStudio, are presented that facilitate data visualization (a dashboard) and data exploration (a filtering app) of the original and aggregated records.
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Keywords: |
Ecuador |
canopy |
Climate data |
Berdugo Moreno, M.B.; Gradstein, S.R.; Guérot, L.; León-Yánez, S.; Bendix, J. & Bader, M. (2022): Diversity patterns of epiphytic bryophytes across spatial scales: Species-rich crowns and beta-diverse trunks. Biotropica 54(4), 893-905.
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DOI: 10.1111/btp.13113
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Abstract:
Abstract:
Tropical forests are highly diverse at many spatial scales. In these forests, small-sized canopy organisms can form species-rich communities already within a few cm2. Understanding how species numbers increase when expanding the sampling along the tree and the forest is critical for evaluating the processes maintaining biodiversity. We therefore studied epiphytic bryophyte diversity in tree crowns and along trunks across spatial scales in a tropical lowland forest in Amazonian Ecuador, sampling bryophytes in 100-cm2 quadrats on 24 trees (15–22 quadrats each) using a spatially hierarchical design, analyzing alpha and beta diversity at different spatial grains and extents. At the smallest grain, tree crowns held more bryophyte species than trunks, but at the largest grain the trunks held most species (93 vs. 77), as beta diversity was higher among trunks than among crowns. However, except for trunks at the largest extent (all 24 trees), the highest beta diversity among quadrats was always found between crowns and trunks. Species turnover strongly dominated beta diversity at all spatial scales. This and the high species richness resulted in highly unpredictable species compositions, especially in trunk communities. These patterns suggest different controls of diversity in crowns than on trunks and an important role for chance processes in shaping these communities. The high beta diversity within trees, in combination with the large effort involved in climbing trees, implies that diversity sampling of small canopy organisms is most efficient using an intensive (many plots on few trees) rather than extensive (many trees across a large area) sampling.
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Keywords: |
Ecuador |
Biodiversity |
epiphytic bryophytes |
Contreras, P.; Orellana-Alvear, J.; Muñoz, P.; Bendix, J. & Celleri, R. (2021): Influence of Random Forest Hyperparameterization on Short-Term Runoff Forecasting in an Andean Mountain Catchment. Atmosphere 12(2), 1-16.
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DOI: 10.3390/atmos12020238
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Abstract:
Abstract:
The Random Forest (RF) algorithm, a decision-tree-based technique, has become a promising approach for applications addressing runoff forecasting in remote areas. This machine learning approach can overcome the limitations of scarce spatio-temporal data and physical parameters needed for process-based hydrological models. However, the influence of RF hyperparameters is still uncertain and needs to be explored. Therefore, the aim of this study is to analyze the sensitivity of RF runoff forecasting models of varying lead time to the hyperparameters of the algorithm. For this, models were trained by using (a) default and (b) extensive hyperparameter combinations through a grid-search approach that allow reaching the optimal set. Model performances were assessed based on the R2, %Bias, and RMSE metrics. We found that: (i) The most influencing hyperparameter is the number of trees in the forest, however the combination of the depth of the tree and the number of features hyperparameters produced the highest variability-instability on the models. (ii) Hyperparameter optimization significantly improved model performance for higher lead times (12- and 24-h). For instance, the performance of the 12-h forecasting model under default RF hyperparameters improved to R2 = 0.41 after optimization (gain of 0.17). However, for short lead times (4-h) there was no significant model improvement (0.69 < R2 < 0.70). (iii) There is a range of values for each hyperparameter in which the performance of the model is not significantly affected but remains close to the optimal. Thus, a compromise between hyperparameter interactions (i.e., their values) can produce similar high model performances. Model improvements after optimization can be explained from a hydrological point of view, the generalization ability for lead times larger than the concentration time of the catchment tend to rely more on hyperparameterization than in what they can learn from the input data. This insight can help in the development of operational early warning systems
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Keywords: |
Ecuador |
Random forests |
discharge |
Water fluxes |
Turini, N.; Thies, B.; Horna, N. & Bendix, J. (2021): Random forest-based rainfall retrieval for Ecuador using GOES-16 and IMERG-V06 data. European Journal of Remote Sensing 54(1), 117-139.
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DOI: 10.1080/22797254.2021.1884002
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Abstract:
Abstract:
A new satellite-based algorithm for rainfall retrieval in high spatio-temporal resolution fo
Ecuador is presented. The algorithm relies on the precipitation information from the Integrated
Multi-SatEllite Retrieval for the Global Precipitation Measurement (GPM) (IMERG) and infrared
(IR) data from the Geostationary Operational Environmental Satellite-16 (GOES-16). It wa
developed to (i) classify the rainfall area (ii) assign the rainfall rate. In each step, we selected
the most important predictors and hyperparameter tuning parameters monthly. Between 19
April 2017 and 30 November 2017, brightness temperature derived from the GOES-16 IR
channels and ancillary geo-information were trained with microwave-only IMERG-V06 using
random forest (RF). Validation was done against independent microwave-only IMERG-V06
information not used for training. The validation results showed the new rainfall retrieva
technique (multispectral) outperforms the IR-only IMERG rainfall product. This offers using
the multispectral IR data can improve the retrieval performance compared to single-spectrum
IR approaches. The standard verification scored a median Heidke skill score of ~0.6 for the rain
area delineation and R between ~0.5 and ~0.62 for the rainfall rate assignment, indicating
uncertainties for Andes’s high elevation. Comparison of RF rainfall rates in 2 km2
resolution
with daily rain gauge measurements reveals the correlation of R = ~0.33.
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Keywords: |
Ecuador |
GOES |
rainfall |
Random forests |
Knoke, T.; Paul, C.; Rammig, A.; Gosling, E.; Hildebrandt, P.; Härtl, F.; Peters, T.; Richter, M.; Diertl, K.; Castro, L.M.; Calvas, B.; Ochoa, S.; Valle-Carrión, L.A.; Hamer, U.; Tischer, A.; Potthast, K.; Windhorst, D.; Homeier, J.; Wilcke, W.; Velescu, A.; Gerique, A.; Pohle, P.; Adams, J.; Breuer, L.; Mosandl, R.; Beck, E.; Weber, M.; Stimm, B.; Silva, B.; Verburg, P.H. & Bendix, J. (2020): Accounting for multiple ecosystem services in a simulation of land-use decisions: Does it reduce tropical deforestation?. Global Change Biology 26( ), 1-22.
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DOI: 10.1111/gcb.15003
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Abstract:
Abstract:
Abstract Conversion of tropical forests is among the primary causes of global environmental change. The loss of their important environmental services has prompted calls to integrate ecosystem services (ES) in addition to socio-economic objectives in decision-making. To test the effect of accounting for both ES and socio-economic objectives in land-use decisions, we develop a new dynamic approach to model deforestation scenarios for tropical mountain forests. We integrate multi-objective optimization of land allocation with an innovative approach to consider uncertainty spaces for each objective. These uncertainty spaces account for potential variability among decision-makers, who may have different expectations about the future. When optimizing only socio-economic objectives, the model continues the past trend in deforestation (1975–2015) in the projected land-use allocation (2015–2070). Based on indicators for biomass production, carbon storage, climate and water regulation, and soil quality, we show that considering multiple ES in addition to the socio-economic objectives has heterogeneous effects on land-use allocation. It saves some natural forest if the natural forest share is below 38%, and can stop deforestation once the natural forest share drops below 10%. For landscapes with high shares of forest (38%–80% in our study), accounting for multiple ES under high uncertainty of their indicators may, however, accelerate deforestation. For such multifunctional landscapes, two main effects prevail: (a) accelerated expansion of diversified non-natural areas to elevate the levels of the indicators and (b) increased landscape diversification to maintain multiple ES, reducing the proportion of natural forest. Only when accounting for vascular plant species richness as an explicit objective in the optimization, deforestation was consistently reduced. Aiming for multifunctional landscapes may therefore conflict with the aim of reducing deforestation, which we can quantify here for the first time. Our findings are relevant for identifying types of landscapes where this conflict may arise and to better align respective policies.
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Keywords: |
Ecuador |
biodiversity |
ecosystem services |
land allocation |
landscape restoration |
robust optimization |
Carrillo-Rojas, G.; Silva, B.; Rollenbeck, R.; Celleri, R. & Bendix, J. (2018): The breathing of the Andean highlands: Net ecosystem exchange and evapotranspiration over the páramo of southern Ecuador. Agricultural and Forest Meteorology 265, 30-47.
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DOI: 10.1016/j.agrformet.2018.11.006
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Abstract:
Abstract:
Atmospheric carbon (CO2) exchange, evapotranspiration (ET) processes, and their interactions with climatic drivers across tropical alpine grasslands are poorly understood. This lack of understanding is particularly evident for the páramo, the highest vegetated frontier in the northern Andes, the main source of water for inter-Andean cities, and a large carbon storage area. Studies of CO2 and ET fluxes via the standard Eddy Covariance (EC) technique have never been applied to this region, limiting the understanding of diurnal / nocturnal exchanges and budget estimations. In this paper, we report the first EC analysis conducted on the Andean páramo (3765?m a.s.l.); this analysis measured CO2, ET, and micrometeorological variables over two years (2016–2018) to understand their interactions with climatic / biophysical controls. The páramo was found to be a source of CO2 and exhibited a net positive exchange (mean = +99?±?30 gC m?2 per year). The light-responses of net CO2 exchange and the primary productivity were correlated and model-parameterized. Evapotranspiration was 635?±?9?mm per year (51% of the annual rainfall total), and we obtained crop coefficients for the dominant vegetation (Tussock grass) based on reference-ET models FAO56 and ASCE-ERWI (0.90 and 0.78, respectively). We also compared our results to those from other high-altitude (alpine) and high-latitude grasslands (tundra). Finally, we demonstrate that our measurement period is representative of the páramo’s longer-term climate dynamics. Our investigation contributes to the body of knowledge on the land surface-atmosphere processes of the tropical Andes and supports decision-making about ecosystem services management and the preservation of this vulnerable biome.
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Keywords: |
Ecuador |
Paramo |
evapotranspiration |
Tropical Andes |
Eddy covariance |
Carbon |
Gonzalez, V.; Fries, A.; Rollenbeck, R.; Paladines, J.; Oñate-Valdivieso, F. & Bendix, J. (2016): Assessment of deforestation during the last decades in Ecuador using NOAA-AVHRR satellite data. Erdkunde 70(3), 217-235.
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DOI: 10.3112/erdkunde.2016.03.02
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Abstract:
Abstract:
Human activities during the last decades provoked a notable reduction in global forest cover. Knowing that
forest stands act as stock and sinks for carbon and other greenhouse gases, it is important to determine the existing forest
cover at country level and to calculate annual deforestation rates. This work uses NOAA satellite images in a resolution of
1 km x 1 km to classify the surface of continental Ecuador in “forest” – “non-forest” pixels and to estimate the annual
deforestation rate from 1986 to 2001 as well as from 2001 to 2008. The method is based on a decision tree algorithm that
includes different spectral bands of the NOAA-AVHRR sensor and additional topographic and meteorological parameters.
The results show that the total forest cover of continental Ecuador was reduced from 48.1 % in 1986 to 36.8 % in 2008. The
calculated annual deforestation rates indicate that forest reduction increased during the last decade. The most affected area
is the Coastal Lowland, due to the enhanced population pressure, followed by the Amazon Basin, not only caused by the
governmental supported oil and mining industry, but also due to the uncontrolled timber extraction. The Andean Highland
has been less affected, because the major parts of this region were deforested before, during the Pre-Columbian-Era.
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Keywords: |
Ecuador |
NOAA-AVHRR |
deforestation |
Knoke, T.; Paul, C.; Hildebrandt, P.; Calvas, B.; Castro, L.M.; Härtl, F.; Döllerer, M.; Hamer, U.; Windhorst, D.; Wiersma, Y.F.; Curatola Fernández, G.F.; Obermeier, W.; Adams, J.; Breuer, L.; Mosandl, R.; Beck, E.; Weber, M.; Stimm, B.; Haber, W.; Fürst, C. & Bendix, J. (2016): Compositional diversity of rehabilitated tropical lands supports multiple ecosystem services and buffers uncertainties. Nature Communications 7, 11877.
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DOI: 10.1038/ncomms11877
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Abstract:
Abstract:
High landscape diversity is assumed to increase the number and level of ecosystem services.
However, the interactions between ecosystem service provision, disturbance and landscape
composition are poorly understood. Here we present a novel approach to include uncertainty
in the optimization of land allocation for improving the provision of multiple ecosystem
services. We refer to the rehabilitation of abandoned agricultural lands in Ecuador including
two types of both afforestation and pasture rehabilitation, together with a succession option.
Our results show that high compositional landscape diversity supports multiple ecosystem services (multifunction effect). This implicitly provides a buffer against uncertainty. Our work shows that active integration of uncertainty is only important when optimizing single or highly correlated ecosystem services and that the multifunction effect on landscape diversity is stronger than the uncertainty effect. This is an important insight to support a land-use planning based on ecosystem services.
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Keywords: |
Ecuador |
Community composition |
abandoned pastures |
Ecosystem Services |
compositional diversity |
Uncertainities |
rehabilitation |
Wallis, C.I.B.; Paulsch, D.; Zeilinger, J.; Silva, B.; Curatola Fernández, G.F.; Brandl, R.; Farwig, N. & Bendix, J. (2016): Contrasting performance of Lidar and optical texture models in predicting avian diversity in a tropical mountain forest. Remote Sensing of Environment 174, 223-232.
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DOI: 10.1016/j.rse.2015.12.019
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Abstract:
Abstract:
Ecosystems worldwide are threatened by the increasing impact of land use and climate change. To protect their diversity and functionality, spatially explicit monitoring systems are needed. In remote areas, monitoring is difficult and recurrent field surveys are costly. By using Lidar or the more cost-effective and repetitive optical satellite data, remote sensing could provide proxies for habitat structure supporting measures for the conservation of biodiversity. Here we compared the explanatory power of both, airborne Lidar and optical satellite data in modeling the spatial distribution of biodiversity of birds across a complex tropical mountain forest ecosystem in southeastern Ecuador. Weused data fromfield surveys of birds and chose three measures as proxies for different aspects of diversity: (i) Shannon diversity as a measure of ?-diversity that also includes the relative abundance
of species, (ii) phylodiversity as a first proxy for functional diversity, and (iii) community composition as a proxy for combined ?- and ?-diversity.We modeled these diversity estimates using partial least-square regression of Lidar and optical texturemetrics separately and compared themodels using a leave-one-out validated R2 and root mean square error. Bird community information was best predicted by both remote sensing datasets, followed by Shannon diversity and phylodiversity. Our findings reveal a high potential of optical texture metrics for predicting Shannon diversity and a measure of community composition, but not for modeling phylodiversity. Generalizing from the investigated tropical mountain ecosystem,we conclude that texture information retrieved from multispectral data of operational satellite systems could replace costly airborne laser-scanning for modeling certain aspects of biodiversity.
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Keywords: |
Ecuador |
Biodiversity |
Community composition |
Gray level co-occurrence matrix |
Quickbird |
Shannon diversity |
Birds |
Image Texture |
Partial least-square regression |
Phylodiversity |
Carrillo-Rojas, G.; Silva, B.; Cordova, M.; Celleri, R. & Bendix, J. (2016): Dynamic Mapping of Evapotranspiration Using an Energy Balance-Based Model over an Andean Páramo Catchment of Southern Ecuador. Remote Sensing 8(2), 160 (1-24).
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DOI: 10.3390/rs8020160
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Abstract:
Abstract:
Understanding of evapotranspiration (ET) processes over Andean mountain environments is crucial, particularly due to the importance of these regions to deliver water-related ecosystem services. In this context, the detection of spatio-temporal changes in ET remains poorly investigated for specific Andean ecosystems, like the páramo. To overcome this lack of knowledge, we implemented the energy-balance model METRIC with Landsat 7 ETM+ and MODIS-Terra imagery for a páramo catchment. The implementation contemplated adjustments for complex terrain in order to obtain daily, monthly and annual ET maps (between 2013 and 2014). In addition, we compared our results to the global ET product MOD16. Finally, a rigorous validation of the outputs was conducted with residual ET from the water balance. ET retrievals from METRIC (Landsat-based) showed good agreement with the validation-related ET at monthly and annual steps (mean bias error <8 mm·month?1 and annual deviation <17%). However, METRIC (MODIS-based) outputs and the MOD16 product were revealed to be unsuitable for our study due to the low spatial resolution. At last, the plausibility of METRIC to obtain spatial ET retrievals using higher resolution satellite data is demonstrated, which constitutes the first contribution to the understanding of spatially-explicit ET over an alpine catchment in the neo-tropical Andes.
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Keywords: |
Ecuador |
remote sensing |
Andes |
Landsat |
MODIS |
Tropical Mountain Ecosystem |
Paramo |
evapotranspiration |
Kübler, D.; Günter, S.; Hildebrandt, P.; Stimm, B.; Weber, M.; Mosandl, R.; Muñoz, J.; Aguirre, N.; Cabrera, O.; Zeilinger, J. & Silva, B. (2016): Assessing the importance of topographic variables for the spatial distribution of tree species in a tropical mountain forest.. Erdkunde 70(1), 19-47.
Campozano, L.; Celleri, R.; Trachte, K.; Bendix, J. & Samaniego, E. (2016): Rainfall and Cloud Dynamics in the Andes: A Southern Ecuador Case Study. Advances in Meteorology 2016(ID 3192765), 15.
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DOI: 10.1155/2016/3192765
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Abstract:
Abstract:
Mountain regions worldwide present a pronounced spatiotemporal precipitation variability, which added to scarce monitoring
networks limits our understanding of the generation processes involved. To improve our understanding of clouds and precipitation
dynamics and cross-scale generation processes in mountain regions, we analyzed spatiotemporal rainfall patterns using satellite
cloud products (SCP) in the Paute basin (900–4200m a.s.l. and 6481 km2) in the Andes of Ecuador. Precipitation models, using
SCP and GIS data, reveal the spatial extension of three regimes: a three-modal (TM) regime present across the basin, a bimodal
(BM) regime, along sheltered valleys, and a unimodal (UM) regime at windward slopes of the eastern cordillera. Subsequently, the
spatiotemporal analysis using synoptic information shows that the dry season of the BM regime during boreal summer is caused
by strong subsidence inhibiting convective clouds formation.Meanwhile, in UMregions, low advective shallow cap clouds mainly
cause precipitation, influenced by water vapor from the Amazon and enhanced easterlies during boreal summer. TM regions are
transition zones fromUMto BMand zones on the windward slopes of the western cordillera. These results highlight the suitability
of satellite and GIS data-driven statistical models to study spatiotemporal rainfall seasonality and generation processes in complex
terrain, as the Andes.
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Keywords: |
Ecuador |
rainfall |
Cordova, M.; Carrillo-Rojas, G.; Crespo, P.; Wilcox, B. & Celleri, R. (2015): Evaluation of the Penman-Monteith (FAO 56 PM) Method for Calculating Reference Evapotranspiration Using Limited Data: Application to the Wet Páramo of Southern Ecuador. Mountain Research and Development 35(3), 230-239.
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DOI: 10.1659/MRD-JOURNAL-D-14-0024.1
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Abstract:
Abstract:
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 páramo, 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 páramo 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 be as high as 14%; and if all data except temperature are estimated, errors higher than 30% may result. Our study demonstrates the importance of using high-quality meteorological data for calculating ETo in the wet páramo landscapes of southern Ecuador.
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Keywords: |
Ecuador |
Andes |
Tropical Mountain Ecosystem |
mount |
mountainous regions |
reference evapotranspiration |
meteorological data |
limited data |
Penman-Monteith |
Curatola Fernández, G.F.; Obermeier, W.; Gerique, A.; López Sandoval, M.F.; Lehnert, L.; Thies, B. & Bendix, J. (2015): Land Cover Change in the Andes of Southern Ecuador - Patterns and Drivers. Remote Sensing 7(3), 2509-2542.
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DOI: 10.3390/rs70302509
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Abstract:
Abstract:
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.
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Keywords: |
Ecuador |
land cover change |
remote sensing |
Andes |
fragmentation |
bracken fern |
deforestation drivers |
Landsat |
image pre-processing |
attractors of landscape change |
Curatola Fernández, G.F.; Silva, B.; Gawlik, J.; Thies, B. & Bendix, J. (2013): Bracken fern frond status classification in the Andes of southern Ecuador: combining multispectral satellite data and field spectroscopy. International Journal of Remote Sensing 34, 7020-7037.
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DOI: 10.1080/01431161.2013.813091
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Abstract:
Abstract:
In the anthropogenic fire-disturbed ecosystem of the San Francisco Valley in the Andes of southeastern Ecuador, dense stands of an aggressive invasive weed, the southern bracken fern (Pteridium arachnoideum and Pteridium caudatum), dominate the landscape. To secure sustainable land management in the region, a comprehensive understanding of bracken spatial-distribution patterns and life cycle dynamics is crucial. We investigated the possibility of detecting bracken-infested areas and frond status (live, fungi-infected, and dead) by means of a high-resolution QuickBird scene from October 2010 and spectral signatures based on field spectroscopy. After image pre-processing, a two-step classification procedure first delineates the bracken-infested area by means of a maximum-likelihood hard classification. The probability-guided unmixing classifier with field-derived end-members is applied in the second step to obtain the fractional cover of the different frond statuses per pixel. The results showed that the areas infested by bracken could be distinguished from the other land-cover classes with high accuracy (overall accuracy of 0.9973). Also, the three frond statuses could be accurately classified at the sub-pixel level. The ‘dead’ class was the dominant frond status at the time of image acquisition (October 2010). We conclude that the extreme dry spell in October 2010 was particularly responsible for this dominance.
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Keywords: |
Ecuador |
remote sensing |
bracken fern |
image pre-processing |
QuickBird |
Peters, T.; Drobnik, T.; Meyer, H.; Rankl, M.; Richter, M.; Rollenbeck, R.; Thies, B. & Bendix, J. (2013): Environmental Changes Affecting the Andes of Ecuador. In: Bendix, J., Beck, E., Bräuning, A., Makeschin, F., Mosandl, R., Scheu, S., Wilcke, W. (eds.): Ecosystem Services, Biodiversity and Environmental Change in a Tropical Mountain Ecosystem of South ( ), Springer, Berlin, 20-34.
Lotz, T.; Bendix, J. & Dobbermann, M. (2012-09-12). Information Management System FOR816dw - Experiences derived from the development and running of an EML‐based data platform for the ecological research unit FOR816. Presented at GfÖ-2012, Session: Data - publishing, linking, using ecological data online, Lüneburg / Germany.
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Abstract:
Abstract:
One crucial aspect within most joint projects in ecosystem research is the way of data storage and exchange. The Data Warehouse of the DFG-Research Unit 816 (FOR816dw) provides an integrative platform to enable the retrieval, transfer, storage, and analysis of scientific data of various ecological disciplines, focused on biodiversity research.
To structure the data and to make it usable by other scientists a robust metadata concept had to be implemented. The Ecological Metadata Language (EML: www.knb.ecoinformatics.org/software/eml) provides a sophisticated XML-based scheme to describe scientific ecological data sets. The relational database structure of the FOR816dw is based on the metadata logic of EML and contains at least all mandatory fields to be compliant to this specification. The metadata are transmitted by the data owner via a browser based wizard during the data upload. They can be queried for temporal, spatial, and thematically features to find data sets in the data pool. Furthermore the metadata bears information on the data set creator, the intellectual rights, and the data collection/processing workflow of each contained attribute of a data set. The adaption of the concept to describe each attribute (variable) of a data set establishes the granulated storage and analysis of the tabular data set values. All information are safely stored in the relational database and can be filtered, selected and reused.
Beside the storage and maintenance of data sets and metadata the FOR816dw provides the management of administrative tasks of the research group. The user management, the project structure, a news system, a mailing-lists generator, the travel reimbursement, and the station booking system is based on the same personnel and project specific data used for the metadata description of the scientific data sets. The project`s webpage (www.tropicalmountainforest.org) is the single point of contact for the project members and provides a user-friendly access to all information of the DFG-Research Unit 816 ?Biodiversity and Sustainable Management of a Megadiverse Mountain Ecosystem in South Ecuador?.
After six years of development and running, an open source release will be available at the termination of the FOR816 in March 2013. With this in view we want to review some technical and conceptual solutions and discuss the acceptance by the users. Is the representation of EML in a relational database possible? Is the combination of project administration and data management in one platform useful? Up to what level of detail are the users willing to submit and describe their data?
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Keywords: |
FOR816dw |
datawarehouse |
Ecuador |
peer reviewed |
Fries, A. (2012): Implementation of new methods for the regionalization of climate data Philipps-University-Marburg, phd thesis
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The thermal structure of a megadiverse mountain ecosystem in southern Ecuador is examined on the basis of temperature measurements inside the natural mountain forest and at open sites along an altitudinal gradient from 1700m to 3200m. The data is used to calculated maps of monthly average minimum, mean and maximum 2m air temperature for the period 1999-2007, needed by ecological projects. The maps are generated by combining the straightforward detrending technique by using a Digital Elevation Model and satellite-based land cover classification. The results reveal a clear thermal differentiation over the year, partly triggered by the change of synoptic weather situation but also by land cover effects. Thermal amplitudes are particularly low during the main rainy season when cloudiness and air humidity are high but markedly pronounced in the relative dry season when daily irradiance and outgoing nocturnal radiation causes distinct differences between the land cover units. Particularly the lower pasture areas gained by slash and burn of the natural forest exhibit the most extreme thermal conditions while the atmosphere inside the mountain forest is slightly cooler due to the regulating effects of the dense vegetation. Thus, clearing the forest clearly reduces the thermal regulation function (regulating ecosystem services) of the ecosystem which might become problematic under future global warming.
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Ecuador |
climate |
Regionalization |
air temperature |
thermal structure |