Publications
Found 516 publication(s)
- of type article
Sorensen, M.C.; Donoso, I.; Neuschulz, E.; Schleuning, M. & Mueller, T. (2020): Community-wide seed dispersal distances peak at low levels of specialisation in size-structured networks. Oikos 129(11), 1727-1738.
Knoke, T.; Gosling, E. & Paul, C. (2020): Use and misuse of the net present value in environmental studies. Ecological Economics 174(106664), 1-15.
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DOI: 10.1016/j.ecolecon.2020.106664
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Abstract:
Abstract:
Environmental studies regularly use the net present value (NPV) to value benefits and costs of projects. However, the NPV disregards whether the stream of net benefits is steady or volatile and ignores the distribution of net benefits among different groups of people. Here we test alternatives to NPV, building on two example cases: 1) We use discounted utility (DU) to evaluate land-use projects and calculate opportunity costs for avoided deforesta-tion. 2) We simulate decision-making on tropical deforestation, whereby we use multiple decision criteria to consider the distribution of net benefits between two groups: farmers and conservationists. Results show considerable differences in the ranking of projects between DU and NPV, when projects are not marginal. Compared to DU, NPV regularly overestimates the value of forest plantations. Moreover, NPV tends to overstate the opportunity costs of avoiding deforestation in terms of saved carbon emissions. Not accounting for the distribution of net benefits in optimizing land-use allocation leads to suboptimal simulated deforestation scenarios. We therefore suggest that future studies should either also use DU to value economic consequences of projects or that they use the NPV as only one among several socio-economic and ecological decision criteria.
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Keywords: |
land allocation |
Net present value |
Discounted utility |
Euclidian distance |
Uncertainty |
Ochoa Moreno, S.; Härtl, F.; Paul, C. & Knoke, T. (2019): Cropping systems are homogenized by off-farm income – Empirical evidence from small-scale farming systems in dry forests of southern Ecuador. Land Use Policy 82, 204-219.
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DOI: 10.1016/j.landusepol.2018.11.025
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Abstract:
Abstract:
Diversified agricultural landscapes have been shown to provide a wide range of ecosystem services. It is often stated that the main motivation behind growing multiple crops within a farm is to buffer farm income against market and climate risks. However, household characteristics, particularly the amount of off-farm income may also influence farm diversity. While the drivers of diversifying farm income have been investigated extensively,the ecologically important level of land-use diversity on a farm has seldom been used as a dependent variable.
Based on data from 163 households, this paper analyzes the impact of social, economic and demographic household characteristics on crop diversification for farms located around the Laipuna Reserve in the dry forests of southern Ecuador. Using a Heckman two-step regression model, we identified factors that influence a) the probability that a farm will be diversified (PD) and b) the degree of diversification at the farm level (LUD), quantified by the Shannon index. We found that PD is positively related to the percentage of household members who depend on family income but do not work (economic dependence ratio), as well as river access and available family labor force. PD is inversely related to access to financial support (i.e. social payments and credits) and off-farm income. LUD is positively related to the number of household members and the age of the head of the household, and correlates negatively with labor force, financial support and off-farm income. Our results demonstrate that land-use diversification is not only a strategy to reduce risk, but it is also driven by farmers’ efforts to meet household, mainly subsistence, needs. Moreover, we also demonstrate that when households have access to financial support and off-farm income, the pressure to diversify their crops diminishes. Finally, we argue that forest and agricultural policies should impose instruments to support land-use diversification financially, while acknowledging the importance of financial support and off-farm income for household
economies. Strategies to reduce poverty should be accompanied by direct support of land-use diversification, infrastructure development and agricultural training.
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Keywords: |
land use |
land diversification |
Cropping |
Graefe, S.; Rodrigo, R.; Cueva, E.; Butz, P.; Werner, F.A. & Homeier, J. (2020): Impact of disturbance on forest structure and tree species composition in a tropical dry forest of South Ecuador. Ecotropica 22, 202002.
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DOI: 10.30427/ecotrop202002
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Abstract:
Abstract:
Tropical dry forests (TDFs) are often degraded and fragmented through human impact, which is also the case in Southern Ecuador, where land-use pressure is high. In this context we studied tree species composition and forest structure in a protected and adjacent disturbed TDF at altitudes between 560-1080 m asl. Fabaceae and Malvaceae were identified as the most important tree families in both forest types. The disturbed forest displayed lower tree species richness than the protected forest, and the gap in species richness between the two forest types increased with increasing altitude. Ten species of the protected forest were not recorded in the disturbed forest, two of them endemic. The disturbed site was further characterized by a lower number of stems but with larger diameters, in comparison with the protected forest. The majority of the most abundant tree species in the disturbed forest had rather low wood densities, but also the combination of high wood density with browsing tolerance and high resprouting capacity was encountered, and seems to be advantageous for getting established in such sites. Although certain tree species were well represented in the disturbed forest, some endemic species with relatively low abundances (e.g. Simira ecuadorensis, Prockia crucis) should receive more conservation attention.
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Keywords: |
species richness |
altitude |
importance value index |
Tumbesian dry forest |
wood density |
Palomeque, X.; Patiño Uyaguari, C.; Marin, F.; Palacios, M. & Stimm, B. (2020): Effects of storage on seed germination and viability for three native tree species of Ecuador. Trees online, 1-11.
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DOI: 10.1007/s00468-020-02018-2
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Abstract:
Many forests restoration programs and efforts depend on seeds. Particularly in the Andes, further information regarding seed germination requirements and seed storage behavior is necessary. The aim of this study was to evaluate the effects of storage conditions on the germination percentage, the viability and the coefficient of velocity of germination for seeds of three native tree species (Cedrela montana, Weinmannia fagaroides and Oreocallis grandiflora). Under controlled conditions, the seeds were exposed to three levels of seed moisture content and storage temperatures (5 °C, 10 °C and room temperature at approx. 19 °C) for 3, 6 and 12 months. The results showed that at 3–6 months of seed storage under temperatures of 5 and 10 °C, the seeds had a high percentage of germination, viability and germination speed for C. montana and W. fagaroides compared to those stored at room temperature. At 12 months of storage, there was a marked reduction in seed germination in all treatments for both species. Furthermore, the seed germination and viability of O. grandiflora was not influenced by any of the above storage treatments. However, at the end of the experiment a slight decrease was observed, hence this species might be tolerant to medium- and long-term storage conditions. Though limited to just three co-occurring species, the study provided insight into the variability in responses to storage, with preliminary indications of appropriate storage conditions to maximize storability of seeds for restoration programs. Importantly, the study demonstrated the need for empirical testing of storage responses (temperature and duration) of seeds before subjecting untested species to a particular storage regime.
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Keywords: |
Seed storage behavior |
Reforestation |
ex situ conservation |
seed management |
Cueva Ortiz, J.L.; Espinosa, C.I.; Aguirre-Mendoza, Z.; Gusmán-Montalván, E.; Weber, M. & Hildebrandt, P. (2020): Natural Regeneration in the Tumbesian Dry Forest: Identification of the Drivers Affecting Abundance and Diversity. Scientific Reports 10( 9786), 13.
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DOI: 10.1038/s41598-020-66743-x
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Abstract:
Tropical and subtropical dry forests make up the world’s largest terrestrial ecosystem. However, these forests have been used to establish several productive activities, such as growing crops, rearing livestock, and using the forest resources, due to their ease of access and climatic conditions, which has led to this ecosystem becoming highly threatened. Therefore, this research assessed the effects of anthropogenic pressures and a number of abiotic variables on natural regeneration in dry forests in the Tumbesian region by addressing three research questions: (a) What is the status of natural regeneration in terms of abundance and diversity? (b) Does livestock grazing and the anthropogenic pressure affect the abundance and diversity of natural regeneration? (c) Does seasonality or grazing have the greatest influence on the regeneration dynamics? Data were obtained from 72 samples (36 fenced and 36 unfenced) during five surveys spanning a 2-year period, and the seedling abundance, mortality, recruitment, species richness and diversity were evaluated using linear mixed models. Natural regeneration was most positively affected by rainy season precipitation, but soil conditions also played an important role. Short-term fences had a major effect on reducing mortality but did not improve the abundance or diversity, whereas cattle grazing significantly affected the abundance of seedlings.
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Keywords: |
grazing |
natural forest regeneration |
anthropogenic pressure |
Cueva Ortiz, J.L.; Espinosa, C.I.; Quiroz Dahik, C.; Aguirre, Z.; Cueva Ortiz, E.; Guzman, E.; Weber, M. & Hildebrandt, P. (2019): Influence of Anthropogenic Factors on the Diversity and Structure of a Dry Forest in the Central Part of the Tumbesian Region (Ecuador–Perú). Forests 10(1), 31.
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DOI: 10.3390/f10010031
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Abstract:
Abstract:
The dry forest of southern Ecuador and northern Perú (called the Tumbesian region) is known for its high diversity, endemism, and healthy conservation state. Nevertheless, the forest is exposed to many threats linked with human activities. To understand the effects of these threats, which have not been appropriately assessed, we pose two questions: (a) What are the diversity and structural situations of the forest? (b) Are anthropogenic activities affecting the composition and structure of the forest? The assessed factors were species richness, diversity, species similarity, abundance, and density. Forest information was obtained from 72 plots (total area 25.92 ha) randomly placed to cover a wide range of stand densities (from 200 to 1100 m a.s.l.). After constructing linear mixed models and selecting the most influential one, we determined the individual influences of 12 predictors. The human pressure index (HPI) was the most negative predictor of forest health, and annual precipitation was the most important abiotic predictor of good health conditions. Livestock grazing did not significantly change the diversity and structure of mature forest. The mean annual temperature and stoniness influenced only the basal area and number of individuals, respectively. The species composition in our study area was not affected by the HPI, but was strongly predicted by annual precipitation.
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Keywords: |
biodiversity |
species richness |
human pressure |
goats |
Kübler, D.; Hildebrandt, P.; Günter, S.; Stimm, B.; Weber, M.; Munoz, J.; Cabrera, O.; Zeilinger, J.; Silva, B. & Mosandl, R. (2020): Effects of silvicultural treatments and topography on individual tree growth in a tropical mountain forest in Ecuador. Forest Ecology and Management 457, 117726.
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DOI: 10.1016/j.foreco.2019.117726
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Abstract:
Abstract:
Few studies have analysed the effect of silvicultural treatments on tree growth in tropical montane forests (TMF). These forests have strong topographic gradients, which influence growth rates and can potentially interact with silvicultural treatments. The present study investigated the relative effects of silvicultural treatments and topography on growth rates at the tree level in a TMF.
For this, we combined two distinct data sources: (1) field data from a silvicultural experiment in the Andes of southern Ecuador where liberation thinnings, i.e. the removal of the strongest crown competitors, were applied to potential crop trees (PCT) in 2004; and (2) topographic variables obtained from a high-resolution digital terrain model created from an airborne LIDAR survey. We fitted all data in a single linear mixed-effect model. Based on monitoring data from 174 released and 200 reference PCTs of 8 timber species, we calculated periodic annual increment (PAI) in DBH 6 years after the silvicultural treatment as our outcome variable. As topographic predictors, we used elevation and a topographic position index. To control for the by-species growth variability we included random intercepts for species and random slopes for the effect of treatment on species in our model.
PAI was significantly influenced by the topographic predictors. Over the elevational gradient, growth rates declined on average by 0.73 mm a−1 per 100 m increase in elevation. For the topographic position, PCTs in valleys had an average PAI of 2.02 mm a−1 compared to 1.04 mm a−1 on ridges. The effect of the silvicultural treatment across all species was only marginally significant, but its effect size was nevertheless within the range, but at the lower end of values reported for other tropical forest ecosystems (reference trees: 1.35 mm a−1; released trees: 1.60 mm a−1). Between species, baseline growth rates as well as the treatment effect varied considerably. Best linear unbiased predictions of species effects suggested that 5 species responded positively to the silvicultural treatment, whereas 3 species showed no treatment effect. Overall, tree growth varied substantially as indicated by the large residual variance that remained unaccounted for in the model.
Our findings indicate that positive effects of silvicultural treatments in TMF are likely to exist, but that they are possibly obfuscated by strong topographical gradients and large between-tree growth variability. Overall, our results suggest that “broad-brush” management prescriptions are not suited for sustainable forest management of TMF. Instead, granular and spatially explicit prescriptions that take the strong impact of topography on diameter growth as well as species-specific responses to silvicultural treatments into account should be favoured.
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Keywords: |
Cedrela montana |
Silvicultural treatments |
Sustainable forest management |
Diameter growth |
Handroanthus chrysanthus |
Cabrera, O.; Hildebrandt, P.; Stimm, B.; Günter, S.; Fries, A. & Mosandl, R. (2020): Functional Diversity Changes after Selective Thinning in a Tropical Mountain Forest in Southern Ecuador. Diversity 12(6), 256.
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DOI: 10.3390/d12060256
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Abstract:
Abstract:
Background: The impact of selective thinning on forest diversity has been extensively studied in temperate and boreal regions. However, in the tropics, knowledge is still poor regarding the impacts of this silvicultural treatment on functional diversity, especially in tropical mountain forests, which are considered to be highly biodiverse ecosystems and also endangered by human activities. By evaluating the changes on functional diversity by using different indicators, hypothesizing that selective thinning significantly affects (directly or indirectly) tropical mountain forests, this work promotes sustainable ecosystem use. Methods: A total of 52 permanent plots of 2500 m2 each were installed in a primary mountain forest in the San Francisco Biological Reserve to assess the impact of this silvicultural treatment. Selective thinning can be defined as a controlled process, in which trees that compete with ecologically and/or valuable timber species are progressively removed to stimulate the development of profitable ones, called potential crop trees (PCT). In doing so, the best specimens remain in the forest stand until their final harvest. After PCT selection, 30 plots were chosen for the intervention, while 22 plots served as control plots. The thinning intensity fluctuated between 4 and 56 trees ha−1 (average 18.8 ± 12.1 stems ha−1). Functional Diversity (FD) indices, including the community weighted mean (CWM), were determined based on six traits using the FD package implemented in R software. The difference between initial and final conditions of functional richness (FRic), functional divergence (FDiv), functional evenness (FEve), functional dispersion (FDis), and Rao quadratic entropy (RaoQ) was modeled using linear mixed models (LMM). As fixed factors, we used all the predictors inherent to structural and ecological forest conditions before and after the selective thinning and as a random variable, we used the membership to nested sampling units. Results: Functional Richness (FRic) showed significant changes after selective thinning, the other indexes (FEve, FDis, FDiv, RaoQ) were only influenced by predictors related to ecological conditions and characteristics of the community.
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Keywords: |
diversity |
tree species richness |
natural forest management |
silvicultural interventions |
Cabrera, O.; Fries, A.; Hildebrandt, P.; Günter, S. & Mosandl, R. (2019): Early Growth Response of Nine Timber Species to Release in a Tropical Mountain Forest of Southern Ecuador. Forests 10(3), 254.
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DOI: 10.3390/f10030254
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Abstract:
Abstract:
Abstract: Research Highlights: This study determined that treatment “release from competitors”
causes different reactions in selected timber species respective to diametrical growth, in which the
initial size of the tree (diametric class) is important. Also, the growth habit and phenological traits
(defoliation) of the species must be considered, which may have an influence on growth after release.
Background and Objectives: The objective of the study was to analyze the diametric growth of nine
timber species after their release to answer the following questions: (i) Can the diametric growth of the
selected timber species be increased by release? (ii) Does the release cause different responses among
the tree species? (iii) Are other factors important, such as the initial diameter at breast height (DBH)
or the general climate conditions? Materials and Methods: Four-hundred and eighty-eight trees
belonging to nine timber species were selected and monitored over a three-year period. Release was
applied to 197 trees, whereas 251 trees served as control trees to evaluate the response of diametrical
growth. To determine the response of the trees, a linear mixed model (GLMM, R package: LMER4)
was used, which was adjusted by a one-way ANOVA test. Results: All species showed a similar
annual cycle respective to diametric increases, which is due to the per-humid climate in the area.
Precipitation is secondary for the diametric growth because sufficient rainfall occurs throughout year.
What is more important, however, are variations in temperature. However, the species responded
differently to release. This is because the initial DBH and growth habit are more important factors.
Therefore, the species could be classified into three specific groups: Positive, negative and no response
to release. Conclusions: Species which prefer open sites responded positively to release, while shade
tolerant species and species with pronounced phenological traits responded negatively. The initial
DBH was also an important factor for diametric increases. This is because trees of class I (20 cm
to 30 cm DBH) responded positively to the treatment, whereas for bigger or older individuals,
the differences decreased or became negative.
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Keywords: |
tree growth |
radial growth change |
tree competition |
silvicultural interventions |
Delsinne, T.; Arias-Penna, T. & Leponce, M. (2013): Effect of rainfall exclusion on ant assemblages in montane rainforests of Ecuador. Basic and Applied Ecology 14(4), 357 - 365.
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DOI: 10.1016/j.baae.2013.04.002
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Abstract:
Abstract:
Models of global climate change generally predict higher rainfall variability, with more intense rainfall events separated by extended dry periods. We experimentally studied the effects of prolonged droughts on diverse ant assemblages found at three elevations in an Ecuadorian montane rainforest. We hypothesized that most species will be negatively affected directly (physiological stress) or indirectly (less food or suitable nesting resources) by drought. We thus expected a decrease in species richness as well as changes in assemblage composition. As the decrease of moisture content was expected to be more marked above ground than in soil, its impact on ants should differ according to their nesting site (dead wood, leaf litter, soil). After 6-month treatments, dead wood, leaf litter and soil samples were on average 53%, 46% and 4% drier under tents than controls, respectively. The drought did not alter overall species richness in the three nesting situations. However, species composition was significantly modified, mostly in dead wood and in leaf litter. Camponotus in dead wood, Strumigenys in leaf litter and Solenopsis in all three microhabitats were more abundant under tents. In contrast, Pheidole in dead wood, and Pachycondyla in leaf litter, were less abundant than in controls. Similar trends were observed at the three study sites. To conclude, after 6-month droughts dominant ant genera in the assemblages were affected differently. In the longer term, alteration of the rainfall regime is therefore expected to have an important impact on ants, as well as on their ecosystem functions and services, through shifts in species dominance and composition.
Zusammenfassung
Die Modelle des globalen Klimawandels prognostizieren im Allgemeinen variablere Niederschläge mit intensiveren Regenfällen, denen ausgedehnte Trockenperioden folgen. Wir untersuchten experimentell die Auswirkungen von längeren Trockenphasen auf verschiedene Ameisengemeinschaften auf drei Höhenstufen im Bergregenwald von Ecuador. Wir stellten die Hypothese auf, dass Trockenheit sich auf die meisten Arten negativ auswirken würde, sei es direkt (physiologischer Stress) oder indirekt (weniger Futter oder geeignetes Nistmaterial). Wir erwarteten daher eine Abnahme des Artenreichtums sowie Veränderungen in der Zusammensetzung der Arten. Da zu erwarten war, dass die Abnahme der Feuchtigkeit über dem Boden deutlicher sein würde als im Boden, sollten die Auswirkungen auf Ameisen je nach Nistplatz (Totholz, Laub, Erdreich) verschieden sein. Nach sechsmonatiger Behandlung waren die Totholz-, Laub und Erdproben unter den Abdeck-Zelten jeweils durchschnittlich 53%, 46% und 4% trockener als an den Kontrollpunkten. Die Trockenheit hat den Artenreichtum insgesamt in den drei Nist-Situationen nicht verändert. Die Zusammensetzung der Arten hatte sich jedoch signifikant verändert, vor allem in Totholz und Laub. Camponotus in Totholz, Strumigenys in Laub und Solenopsis in allen drei Mikrohabitaten waren unter den Zelten häufiger. Andererseits waren Pheidole in Totholz sowie Pachycondyla in Laub weniger häufig als auf den Kontrollflächen. Ähnliche Tendenzen wurden an allen drei untersuchten Orten beobachtet. Zusammenfassend lässt sich sagen, dass die dominanten Ameisengattungen nach sechsmonatigen Trockenphasen unterschiedlich betroffen waren. Langfristig ist daher zu erwarten, dass eine Veränderung der Niederschlagsmuster durch Veränderungen in der Arten-Dominanz und –zusammensetzung wichtige Auswirkungen auf Ameisen hat, sowie auf ihre Funktionen und Dienste im Ökosystem.
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Keywords: |
Climate change |
Elevational gradient |
Formicidae |
Rainfall manipulation |
Precipitation |
Urgiles , N.; Struß, A.; Loján Amijos, P. & Schüßler, A. (2014): Cultured arbuscular mycorrhizal fungi and native soil inocula improve seedling development of two pioneer trees in the Andean region. New Forests 45, 859–874.
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DOI: 10.1007/s11056-014-9442-8
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Abstract:
Abstract:
The tree species Alnus acuminata and Morella pubescens, native to South America, are candidates for soil quality improvement and afforestation of degraded areas and may serve as nurse trees for later inter-planting of other trees, including native crop trees. Both species not only form symbioses with arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF), but also with N2-fixing actinobacteria. Because tree seedlings inoculated with appropriate mycorrhizal fungi in the nursery resist transplanting stress better than non-mycorrhizal seedlings, we evaluated for A. acuminata and M. pubescens the potential of inoculation with mycorrhizal fungi for obtaining robust tree seedlings. For the first time, a laboratory-produced mixed AMF inoculum was tested in comparison with native soil from stands of both tree species, which contains AMF and EMF. Seedlings of both tree species reacted positively to both types of inocula and showed an increase in height, root collar diameter and above- and belowground biomass production, although mycorrhizal root colonization was rather low in M. pubescens. After 6 months, biomass was significantly higher for all mycorrhizal treatments when compared to control treatments, whereas aboveground biomass was approximately doubled for most treatments. To test whether mycorrhiza formation positively influences plant performance under reduced water supply the experiment was conducted under two irrigation regimes. There was no strong response to different levels of watering. Overall, application of native soil inoculum improved growth most. It contained sufficient AMF propagules but potentially also other soil microorganisms that synergistically enhance plant growth performance. However, the AMF inoculum pot-produced under controlled conditions was an efficient alternative for better management of A. acuminata and M. pubescens in the nursery, which in the future may be combined with defined EMF and Frankia inocula for improved management practices.
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Keywords: |
Ecuador |
reforestation |
AM fungi |
Arbuscular mycorrhizal fungi |
Native soil inoculum |
Pioneer trees |
Seedling growth promotion |
Schüßler, A.; Krüger, C. & Urgiles , N. (2016): Phylogenetically diverse AM fungi from Ecuador strongly improve seedling growth of native potential crop trees. Mycorrhiza 26(3), 199--207.
Orellana-Alvear, J.; Celleri, R.; Rollenbeck, R.; Muñoz, P.; Contreras, P. & Bendix, J. (2020): Assessment of Native Radar Reflectivity and Radar Rainfall Estimates for Discharge Forecasting in Mountain Catchments with a Random Forest Model. Remote Sensing 12(12), 1.
Wallis, C.; Homeier, J.; Pena Tamayo, J.E.; Brandl, R.; Farwig, N. & Bendix, J. (2019): Modeling tropical montane forest biomass, productivity and canopy traits with multispectral remote sensing data. Remote Sensing of Environment 225, 77 - 92.
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DOI: 10.1016/j.rse.2019.02.021
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Abstract:
Abstract:
Tropical montane forests, particularly Andean rainforest, are important ecosystems for regional carbon and water cycles as well as for biological diversity and speciation. Owing to their remoteness, however, ecological key-processes are less understood as in the tropical lowlands. Remote sensing allows modeling of variables related to spatial patterns of carbon stocks and fluxes (e.g., biomass) and ecosystem functioning (e.g., functional leaf traits). However, at a landscape scale most studies conducted so far are based on airborne remote sensing data which is often available only locally and for one time-point. In contrast, multispectral satellites at moderate spectral and spatial resolutions are able to provide spatially continuous and repeated observations. Here, we investigated the effectiveness of Landsat-8 imagery in modeling tropical montane forest biomass, its productivity and selected canopy traits. Topographical, spectral and textural metrics were derived as predictors. To train and validate the models, in-situ data was sampled in 54 permanent plots in forests of southern Ecuador distributed within three study sites at 1000 m, 2000 m and 3000 m a.s.l. We used partial least squares regressions to model and map all response variables. Along the whole elevation gradient biomass and productivity models explained 31%, 43%, 69% and 63% of variance in aboveground biomass, annual wood production, fine litter production and aboveground net primary production, respectively. Regression models of canopy traits measured as community weighted means explained 62%, 78%, 65% and 65% of variance in leaf toughness, specific leaf area, foliar N concentration, and foliar P concentration, respectively. Models at single study sites hardly explained variation in aboveground biomass and the annual wood production indicating that these measures are mainly determined by the change of forest types along with elevation. In contrast, the models of fine litter production and canopy traits explained between 8%–85% in variation depending on the study site. We found spectral metrics, in particular a vegetation index using the red and the green band to provide complementary information to topographical metrics. The model performances for estimating leaf toughness, biochemical canopy traits and related fine litter production all improved when adding spectral information. Our findings therefore revealed that differences in fine litter production and canopy traits in our study area are driven by local changes in vegetation edaphically induced by topography. We conclude that Landsat-derived metrics are useful in modeling fine litter production and biochemical canopy traits, in a topographically and ecologically complex tropical montane forest.
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Keywords: |
Ecuador |
Aboveground forest productivity |
Ecosystem process |
Fine litter production |
Foliar N |
Foliar P |
Grey level co-occurrence texture |
Landsat-8 |
Leaf toughness |
Specific leaf area |
Annual wood production |
Astudillo Webster, P.X.; Grass, I.; Siddons, D.; schabo, D. & Farwig, N. (2020): Centrality in species-habitat networks reveals the importance of habitat quality for high-andeans birds in Polylepis woodlands. Ardeola 67(2), 307-324.
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DOI: 10.13157/arla.67.2.2020.ra5
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Abstract:
Abstract:
Habitat loss and landscape fragmentation are important drivers of changes in biodiversity. In fragmented landscapes, bird species are able to use multiple forest patches that may therefore share an important portion of the regional biodiversity. In turn, these patches are linked through their shared bird diversity (i.e. species-habitat networks). Identifying the importance of nodes (e.g. forest patches) in species-habitat networks is increasingly important to improve conservation planning. within this network approach, the relative importance of patches for birds can be identified via centrality indices-measures of the magnitude of shared bird diversity of patches across the entire network (i.e. patch centrality). here, we tested for changes in patch centrality within bird species-patch networks of two habitat guilds, forest specialists and generalists, in relation to patch area, patch shape irregularity and within-patch habitat characteristics across 15 Polylepis woodland patches in a páramo landscape of southern Ecuador. Patch centrality for forest specialists decreased with greater influence of surrounding páramo plants, i.e. an increasing proportion of bunch-grasses and small shrubs, in the within-patch habitat and was unaffected by either patch area or patch shape irregularity. On the other hand, patch centrality for generalists was positively influenced by patch shape irregularity but was unaffected by
patch area or the influence of surrounding páramo plants in the within-patch habitat. Patch centrality reveals that the relative importance of Polylepis woodlands lies in their habitat quality. Forest specialists are dependent on mature Polylepis woodland patches, while generalists benefit from the natural irregular shape of the woodlands. Finally, a species-habitat network approach facilitates the recognition of important Polylepis patches and their characteristics for conservation of the Andean bird communityat a landscape scale.
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Keywords: |
Ecuador |
Paramo |
Tropical Andes |
forest specialist |
habitat guild |
Duenas, J.F.; Camenzind, T.; Roy, J.; Hempel, S.; Homeier, J.; Suarez, J.P. & Rillig, M.C. (2020): Moderate phosphorus additions consistently affect community composition of arbuscular mycorrhizal fungi in tropical montane forests in southern Ecuador. New Phytologist 227, 1505-1518.
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DOI: 10.1111/NPH.16641
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Abstract:
Abstract:
Anthropogenic atmospheric deposition can increase nutrient supply in the most remote ecosystems, potentially affecting soil biodiversity. Arbuscular mycorrhizal fungal (AMF) communities rapidly respond to simulated soil eutrophication in tropical forests. Yet the
limited spatio-temporal extent of such manipulations, together with the often unrealistically high fertilization rates employed, impedes generalization of such responses.
We sequenced mixed root AMF communities within a seven year-long fully factorial nitrogen (N) and phosphorus (P) addition experiment, replicated at three tropical montane forests in southern Ecuador with differing environmental characteristics. We hypothesized
(i) strong shifts in community composition and species richness after long-term fertilization, (ii) site- and (iii) clade-specific responses to N versus P additions depending on local soil fertility and clade life history traits respectively.
Fertilization consistently shifted AMF community composition across sites, but only reduced richness of Glomeraceae. Compositional changes were mainly driven by increases in P supply while richness reductions were observed only after combined N and P additions.
We conclude that moderate increases of N and P exert a mild but consistent effect on tropical AMF communities. To predict the consequences of these shifts, current results need to be supplemented with experiments that characterize local species-specific AMF
functionality.
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Keywords: |
NUMEX |
San Francisco |
Bombuscaro |
Cajanuma |
Nutrient deposition |
Arbuscular mycorrhizal fungi |
Malizia, A.; Blundo, C.; Carilla, J.; Osinaga Acosta, O.; Cuesta, F.; Duque, A.; Aguirre, N.; Aguirre, Z.; Ataroff, M.; Baez, S.; Calderon-Loor, M.; Cayola, L.; Cayuela, L.; Ceballos, S.; Cedillo, H.; Farfan-Rios, W.; Feeley, K.; Fuentes, A.; Gamez-Avarez, L.; Grau, R.; Homeier, J.; Jadan, O.; Llambi, L.; Loza-Rivera, M.; Macia, M.; Malhi, Y.; Malizia, L.; Peralvo, M.; Pinto, E.; Tello, S.; Silman, M. & Young, K. (2020): Elevation and latitude drives structure and tree species composition in Andean forests: Results from a large-scale plot network. PLoS One 15(4), e0231553.
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DOI: 10.1371/journal.pone.0231553
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Abstract:
Abstract:
Our knowledge about the structure and function of Andean forests at regional scales remains limited. Current initiatives to study forests over continental or global scales still have important geographical gaps, particularly in regions such as the tropical and subtropical Andes. In this study, we assessed patterns of structure and tree species diversity along ~ 4000 km of latitude and ~ 4000 m of elevation range in Andean forests. We used the Andean Forest Network (Red de Bosques Andinos, https://redbosques.condesan.org/) database which, at present, includes 491 forest plots (totaling 156.3 ha, ranging from 0.01 to
6 ha) representing a total of 86,964 identified tree stems � 10 cm diameter at breast height belonging to 2341 identified species, 584 genera and 133 botanical families. Tree stem density and basal area increases with elevation while species richness decreases. Stem
density and species richness both decrease with latitude. Subtropical forests have distinct tree species composition compared to those in the tropical region. In addition, floristic similarity of subtropical plots is between 13 to 16% while similarity between tropical forest plots
is between 3% to 9%. Overall, plots ~ 0.5-ha or larger may be preferred for describing patterns at regional scales in order to avoid plot size effects. We highlight the need to promote collaboration and capacity building among researchers in the Andean region (i.e., South-South cooperation) in order to generate and synthesize information at regional scale.
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Keywords: |
forest structure |
tree species richness |
tree species |
Tropical Andes |
Knoke, T.; Paul, C.; Rammig, A.; Gosling, E.; Hildebrandt, P.; Härtl, F.; Peters, T.; Richter, M.; Diertl, K.; Castro, L.M.; Calvas, B.; Ochoa Moreno, 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 |
landscape restoration |
land allocation |
robust optimization |
Beck, E.; Paladines, P.; Paladines, R.; Matt, F.; Farwig, N. & Bendix, J. (2019): Alexander von Humboldt would have loved it: Estación Científica San Francisco.. Ecotropica 21, 201 99.
Dugger, P.; Blendinger, P.; Boehning-Gaese, K.; Chama, L.; Correia, M.; Dehling, D.; Emer, C.; Farwig, N.; Fricke, E.; Galetti, M.; Garcia, D.; Grass, I.; Heleno, R.; Jacomassa, F.; Morales, S.; Moran, C.; Munoz, M.; Neuschulz, E.; Nowak, L.; Piratelli, A.; Pizo, M.; Quitian, M.; Rogers, H.; Ruggera, R.; Saveedra, F.; Sanchez, M.; Sanchez, R.; Santillan, V.; schabo, D.; Ribeiro da Silva, F.; Timoteo, S.; Traveset, A.; Vollstaedt, M. & Schleuning, M. (2019): Seed‐dispersal networks are more specialized in the Neotropics than in the Afrotropics. Global Ecology and Biogeography 28(2), 248-261.
Santillan, V.; Quitian, M.; Tinoco, B.A.; Zarate, E.; Schleuning, M.; Boehning-Gaese, K. & Neuschulz, E. (2019): Direct and indirect effects of elevation, climate and vegetation structure on bird communities on a tropical mountain. Acta Oecologica 102, 103500.
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DOI: 10.1016/j.actao.2019.103500
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Abstract:
Abstract:
Climate and vegetation structure are important predictors of biodiversity along mountain slopes. The drivers of elevational biodiversity gradients are not yet fully resolved. For instance, there is little understanding of how direct and indirect effects of elevation shape species communities along mountain slopes. In this study, we identify the main drivers of bird diversity along an elevational gradient spanning 2000 m in the Ecuadorian Andes. We simultaneously tested the direct and indirect effects of elevation, temperature, precipitation and vegetation structure on overall bird diversity and on frugivorous and insectivorous birds, using structural equation models (SEMs). We found that elevation was mostly indirectly associated with bird diversity, mediated via abiotic (i.e., temperature, precipitation) and biotic (i.e., vegetation structure) factors. We found consistent positive effects of temperature and vegetation structure and negative effects of precipitation on overall bird diversity and on frugivorous and insectivorous birds. In addition, elevation was directly, positively associated with insectivore richness and abundance, but not with that of frugivores. Our results show that climatic factors and vegetation structure jointly shape the richness of bird communities on tropical mountains. However, other factors, such as biotic interactions or different evolutionary histories of lowland and highland communities, may additionally contribute to elevational patterns in bird diversity. Thus, species communities across tropical mountain slopes are shaped by a multitude of abiotic and biotic factors that need to be studied simultaneously for a mechanistic understanding of patterns in biodiversity.
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Keywords: |
avian diversity patterns |
Schleuning, M.; Neuschulz, E.; Albrecht, J.; Bender, I.M.; Bowler, D.; Dehling, D.; Fritz, S.; Hof, C.; Mueller, T.; Nowak, L.; Sorensen, M.; Boehning-Gaese, K. & Kissling, W. (2020): Trait-Based Assessments of Climate-Change Impacts on Interacting Species. Trends in Ecology and Evolution xxx-xxx, xxx-xxx.
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DOI: 10.1016/j.tree.2019.12.010
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Abstract:
Abstract:
Plant–animal interactions are fundamentally important in ecosystems, but have often been ignored by studies of climate-change impacts on biodiversity. Here, we present a trait-based framework for predicting the responses of interacting plants and animals to climate change. We distinguish three pathways along which climate change can impact interacting species in ecological communities: (i) spatial and temporal mismatches in the occurrence and abundance of species, (ii) the formation of novel interactions and secondary extinctions, and (iii) alterations of the dispersal ability of plants. These pathways are mediated by three kinds of functional traits: response traits, matching traits, and dispersal traits. We propose that incorporating these traits into predictive models will improve assessments of the responses of interacting species to climate change.
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Keywords: |
plants |
functional traits |
global change |
animals |
ecological networks |
dispersal |
Seidel, J.; Trachte, K.; Orellana-Alvear, J.; Figueroa, R.; Celleri, R.; Bendix, J.; Fernandez, C. & Huggel, C. (2019): Precipitation Characteristics at Two Locations in the Tropical Andes by Means of Vertically Pointing Micro-Rain Radar Observations. Remote Sensing 11(24), 2985.
Quichimbo Miguitama, P.G.; Jiménez, L.S.; Veintimilla, D.; Potthast, K.; Tischer, A.; Günter, S.; Mosandl, R. & Hamer, U. (2019): Nutrient dynamics in an Andean forest region: a case study of exotic and native species plantations in southern Ecuador. New Forests -, 1 - 22.
Haug, I.; Setaro, S. & Suarez, J.P. (2019): Species composition of arbuscular mycorrhizal communities changes with elevation in the Andes of South Ecuador. PLOS ONE 14(8), 1-19.
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DOI: 10.1371/journal.pone.0221091
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Abstract:
Abstract:
Arbuscular mycorrhizal fungi (AMF) are the most prominent mycobionts of plants in the tropics, yet little is known about their diversity, species compositions and factors driving AMF distribution patterns. To investigate whether elevation and associated vegetation type affect species composition, we sampled 646 mycorrhizal samples in locations between 1000 and 4000 m above sea level (masl) in the South of Ecuador. We estimated diversity, distribution and species compositions of AMF by cloning and Sanger sequencing the 18S rDNA (the section between AML1 and AML2) and subsequent derivation of fungal OTUs based on 99% sequence similarity. In addition, we analyzed the phylogenetic structure of the sites by computing the mean pairwise distance (MPD) and the mean nearest taxon difference (MNTD) for each elevation level. It revealed that AMF species compositions at 1000 and 2000 masl differ from 3000 and 4000 masl. Lower elevations (1000 and 2000 masl) were dominated by members of Glomeraceae, whereas Acaulosporaceae were more abundant in higher elevations (3000 and 4000 masl). Ordination of OTUs with respect to study sites revealed a correlation to elevation with a continuous turnover of species from lower to higher elevations. Most of the abundant OTUs are not endemic to South Ecuador. We also found a high proportion of rare OTUs at all elevations: 79–85% of OTUs occurred in less than 5% of the samples. Phylogenetic community analysis indicated clustering and evenness for most elevation levels indicating that both, stochastic processes and habitat filtering are driving factors of AMF community compositions.
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Keywords: |
species |
arbuscular mycorrhiza |
Andes |
Arbuscular mycorrhizal fungi |
Orellana-Alvear, J.; Celleri, R.; Rollenbeck, R. & Bendix, J. (2019): Optimization of X-Band Radar Rainfall Retrieval in the Southern Andes of Ecuador Using a Random Forest Model. Remote Sensing 11(14), 1632.
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DOI: 10.3390/rs11141632
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Abstract:
Abstract:
Despite many eorts of the radar community, quantitative precipitation estimation (QPE)
from weather radar data remains a challenging topic. The high resolution of X-band radar imagery
in space and time comes with an intricate correction process of reflectivity. The steep and high
mountain topography of the Andes enhances its complexity. This study aims to optimize the rainfall
derivation of the highest X-band radar in the world (4450 m a.s.l.) by using a random forest (RF)
model and single Plan Position Indicator (PPI) scans. The performance of the RFmodel was evaluated
in comparison with the traditional step-wise approach by using both, the Marshall-Palmer and a
site-specific Z–R relationship. Since rain gauge networks are frequently unevenly distributed and
hardly available at real time in mountain regions, bias adjustment was neglected. Results showed an
improvement in the step-wise approach by using the site-specific (instead of the Marshall-Palmer)
Z–R relationship. However, both models highly underestimate the rainfall rate (correlation coecient
< 0.69; slope up to 12). Contrary, the RF model greatly outperformed the step-wise approach in
all testing locations and on dierent rainfall events (correlation coecient up to 0.83; slope = 1.04).
The results are promising and unveil a dierent approach to overcome the high attenuation issues
inherent to X-band radars.
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Keywords: |
South Ecuador |
random forest |
radar |
calibration |
Cajas National Park |
Wilcke, W.; Velescu, A.; Leimer, S.; Bigalke, M.; Boy, J. & Valarezo, C. (2019): Temporal Trends of Phosphorus Cycling in a Tropical Montane Forest in Ecuador During 14 Years. Journal of Geophysical Research: Biogeosciences 124, 1370-1386.
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DOI: 10.1029/2018JG004942
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Abstract:
Abstract:
Increased bioavailability of P can have a negative impact on plant biodiversity. In an approximately 9‐ha catchment under N + P‐limited megadiverse tropical montane forest in Ecuador, we budgeted all major P fluxes and determined whether the P fluxes changed from 1999 to 2013. Furthermore, we assessed which external drivers (rainfall, total P and acid deposition) caused this potential change. Mean (±SD) annual P deposition (bulk+dry) was 240 ± 270 mg/m2, with the SD reflecting the interannual variation. The annual P flux to the soil via throughfall+stemflow+litterfall was 1,400 ± 170 mg/m2 of which 18 ± 9.2% was leached to below the organic layer. The mineral soil retained 80 ± 12% of the P leached from the organic layer. The mean annual P weathering rate was 79 ± 63 mg/m2. The sum of P fluxes was approximately 5 times larger above than below the mineral soil surface, illustrating that P was tightly cycled in the biological part of the forest. The mean annual canopy budget was negative (−120 ± 280 mg/m2); that is, P was leached from the canopy. Throughfall was the largest source of dissolved P. The P catchment budget (total deposition‐streamflow) was positive (200 ± 270 mg/m2); that is, P was retained, mainly in the soil organic layer. From 1999 to 2013, P fluxes with throughfall, stemflow, and streamflow increased significantly. The strongest driver of the P budgets of the canopy and the catchment was total P deposition. Our results demonstrate that mainly biological processes retained deposited P in the vegetation and the organic layer enhancing the internal P cycle.
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Keywords: |
litterfall |
temporal trends |
catchment budget |
weathering rates |
phosphorus fluxes |
González-Jaramillo, V.; Fries, A. & Bendix, J. (2019): AGB Estimation in a Tropical Mountain Forest (TMF) by Means of RGB and Multispectral Images Using an Unmanned Aerial Vehicle (UAV). Remote Sensing 11(12), 1-22.
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DOI: 10.3390/rs11121413
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Abstract:
Abstract:
The present investigation evaluates the accuracy of estimating above-ground biomass (AGB)
by means of two dierent sensors installed onboard an unmanned aerial vehicle (UAV) platform
(DJI Inspire I) because the high costs of very high-resolution imagery provided by satellites or light
detection and ranging (LiDAR) sensors often impede AGB estimation and the determination of
other vegetation parameters. The sensors utilized included an RGB camera (ZENMUSE X3) and a
multispectral camera (Parrot Sequoia), whose images were used for AGB estimation in a natural
tropical mountain forest (TMF) in Southern Ecuador. The total area covered by the sensors included
80 ha at lower elevations characterized by a fast-changing topography and dierent vegetation covers.
From the total area, a core study site of 24 ha was selected for AGB calculation, applying two dierent
methods. The firstmethod used the RGB images and applied the structure formotion (SfM) process to
generate point clouds for a subsequent individual tree classification. Per the classification at tree level,
tree height (H) and diameter at breast height (DBH) could be determined, which are necessary input
parameters to calculate AGB (Mg ha 1) by means of a specific allometric equation for wet forests.
The second method used the multispectral images to calculate the normalized dierence vegetation
index (NDVI), which is the basis for AGB estimation applying an equation for tropical evergreen
forests. The obtained results were validated against a previous AGB estimation for the same area
using LiDAR data. The study found two major results: (i) The NDVI-based AGB estimates obtained
by multispectral drone imagery were less accurate due to the saturation eect in dense tropical forests,
(ii) the photogrammetric approach using RGB images provided reliable AGB estimates comparable
to expensive LiDAR surveys (R2: 0.85). However, the latter is only possible if an auxiliary digital
terrain model (DTM) in very high resolution is available because in dense natural forests the terrain
surface (DTM) is hardly detectable by passive sensors due to the canopy layer, which impedes
ground detection.
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Keywords: |
Ecuador |
mountain rainforest |
UAV |
Biomass |
Drone |
Guallpa, M.; Orellana-Alvear, J. & Bendix, J. (2019): Tropical Andes Radar Precipitation Estimates Need High Temporal and Moderate Spatial Resolution. Water 11(5), 1-22.
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DOI: 10.3390/w11051038
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Abstract:
Abstract:
Weather radar networks are an excellent tool for quantitative precipitation estimation
(QPE), due to their high resolution in space and time, particularly in remote mountain areas such as
the Tropical Andes. Nevertheless, reduction of the temporal and spatial resolution might severely
reduce the quality of QPE. Thus, the main objective of this study was to analyze the impact of spatial
and temporal resolutions of radar data on the cumulative QPE. For this, data from the world’s highest
X-band weather radar (4450 m a.s.l.), located in the Andes of Ecuador (Paute River basin), and from
a rain gauge network were used. Dierent time resolutions (1, 5, 10, 15, 20, 30, and 60 min) and
spatial resolutions (0.5, 0.25, and 0.1 km) were evaluated. An optical flow method was validated
for 11 rainfall events (with dierent features) and applied to enhance the temporal resolution of
radar data to 1-min intervals. The results show that 1-min temporal resolution images are able to
capture rain event features in detail. The radar–rain gauge correlation decreases considerably when
the time resolution increases (r from 0.69 to 0.31, time resolution from 1 to 60 min). No significant
dierence was found in the rain total volume (3%) calculated with the three spatial resolution data.
A spatial resolution of 0.5 km on radar imagery is suitable to quantify rainfall in the AndesMountains.
This study improves knowledge on rainfall spatial distribution in the Ecuadorian Andes, and it will
be the basis for future hydrometeorological studies
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Keywords: |
Cuenca |
radar |
rainfall |
Paute |