Publications
Found 129 publication(s)
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Murkute, C.P.; Sayeed, M.; Pucha-Cofrep, F.; Carrillo-Rojas, G.; Homeier, J.; Limberger, O.; Fries, A.; Bendix, J. & Trachte, K. (2024): Turbulent Energy and Carbon Fluxes in an Andean Montane Forest—Energy Balance and Heat Storage. Forests 15(10), 1828.
Schoen, J.; Keuth, R.; Homeier, J.; Limberger, O.; Bendix, J.; Farwig, N. & Brandl, R. (2024): Do leaf traits shape herbivory in tropical montane rainforests? A multispecies approach. Ecosphere 15(10), 1-15.
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DOI: 10.1002/ecs2.70018
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Abstract:
Abstract:
The co-evolutionary arms race between herbivores and plants forces plants to evolve protection strategies that reduce the palatability of the plant modules attacked by the herbivores. These characteristics of traits have consequences for both the survival of plant individuals and the composition of plant communities. Thus, correlating traits of for instance leaves with herbivory is an important step toward understanding the dynamics of plant populations and communities. Traits can either be measured using conventional lab methods or recently developed spectral sensing techniques. We examined whether leaf traits of trees are related to herbivory in a multispecies approach. Furthermore, we explored whether leaf traits characterized by spectral sensing provide similar relations to herbivory as lab-based leaf traits. We established nine 1-ha square plots evenly distributed over three different forest types in Ecuadorian tropical montane rainforests where we estimated herbivory as the leaf area loss (in square centimeters) of 20 (±5) leaves sampled from the canopies of 380 tree individuals belonging to 51 tree species (7 ± 1 individuals/species) using lab- and spectral-sensing-based methods. For each methodological approach, we ran 100 linear mixed-effects models with all respective leaf traits as predictor and herbivory as response variables for data subsets containing one randomly selected tree individual of each species to estimate the range of the regression coefficients for each trait. Automated stepwise backward selections determined the frequency of each trait having an important influence on herbivory. We found no clear relations between leaf traits and herbivory for neither lab- nor spectral-sensing-based traits. A nested variance component analysis demonstrated that the observed variability was mainly due to the variation in trait concentrations between tree individuals of a species. Our results suggest that snapshot data lead to a mismatch between herbivory and the concentrations of traits during the peak of herbivory. Another explanation could be that environmental conditions or processes along the food web are more important in structuring herbivory than leaf traits.
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Keywords: |
Ecuador |
herbivory |
leaf area loss |
plant defense |
plant nutrients |
secondary metabolites |
spectral sensing |
Urgilés, G.; Celleri, R.; Bendix, J. & Orellana-Alvear, J. (2024): Identification of spatio-temporal patterns in extreme rainfall events in the Tropical Andes: A clustering analysis approach. Meteorological Applications 31(5), e70005.
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DOI: 10.1002/met.70005
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Abstract:
Abstract:
High spatio-temporal variability is a characteristic of extreme rainfall. In
mountainous regions like the Tropical Andes, where intricate orography and
mesoscale atmospheric dynamics greatly impact rainfall systems, this particularly
holds for mountain areas like the Tropical Andes. Thus, the absence of
operational rainfall monitoring networks with high spatio-temporal resolution
has imposed difficulties for a proper analysis of extreme rainfall events in the
Ecuadorian Andes. Nowhere, we present our improved knowledge on rainfall
extremes based on newly available rainfall radar data of this region. In our
study we employ a clustering approach to identify types of extreme rainfall
events and analyze their spatio-temporal characteristics. Based on 3 years of
data obtained from an X-band scanning weather radar data, the study was conducted
in the southern Ecuadorian Tropical Andes at 4450 m a.s.l. By applying
a rainfall threshold, 67 extreme rainfall events were selected. The rainfall characteristics
of each extreme rainfall event, such as the amount of rain, its duration,
its hour, and month of occurrence were determined and used as input
variables of a k-means clustering analysis to group the events into different
classes. The result revealed three main classes of extreme rainfall events. The
first class is characterized by highest rain intensity and lowest duration. The
second class is characterized by its month of occurrence, during the first
5 months of the year. The third class showed lowest rain intensity and highest
duration mainly occurred at higher elevations. The typology of events
advances our understanding of the spatio-temporal characteristics of extreme
rainfall in the Tropical Andes.
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Keywords: |
classification |
rainfall |
Tropical Andes |
weather radar |
Cordova, M.; Orellana-Alvear, J.; Bendix, J.; Rollenbeck, R. & Celleri, R. (2024): Large-scale dynamics of extreme precipitation in the tropical Andes: combining weather radar observations and reanalysis data. Meteorology and Atmospheric Physics 136(4), 27.
Álvarez-Estrella, J.; Muñoz, P.; Bendix, J.; Contreras, P. & Celleri, R. (2024): Enhancing Peak Runoff Forecasting through Feature Engineering Applied to X-Band Radar Data. Water 16(7), 968.
Schoen, J.; Tiede, Y.; Becker, M.; Donoso, D.A.; Homeier, J.; Limberger, O.; Bendix, J.; Farwig, N. & Brandl, R. (2023): Effects of leaf traits of tropical trees on the abundance and body mass of herbivorous arthropod communities. PLOS ONE -(-), 1 - 21.
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DOI: 10.1371/journal.pone.0288276
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Abstract:
Abstract:
In tropical forests, herbivorous arthropods remove between 7% up to 48% of leaf area,
which has forced plants to evolve defense strategies. These strategies influence the palat-
ability of leaves. Palatability, which reflects a syndrome of leaf traits, in turn influences both
the abundance and the mean body mass not only of particular arthropod taxa but also of the
total communities. In this study, we tested two hypotheses: (H1) The abundance of two
important chewer guilds (‘leaf chewers’ and ‘rostrum chewers’), dominant components of
arthropod communities, is positively related to the palatability of host trees. (H2) Lower pal-
atability leads to an increased mean body mass of chewers (Jarman-Bell principle). Arthro-
pods were collected by fogging the canopies of 90 tropical trees representing 31 species in
three plots at 1000 m and three at 2000 m a.s.l. Palatability was assessed by measuring
several ‘leaf traits’ of each host tree and by conducting a feeding trial with the generalist her-
bivore Gryllus assimilis (Orthoptera, Gryllidae). Leaf traits provided partial support for H1, as
abundance of leaf chewers but not of rostrum chewers was positively affected by the experi-
mentally estimated palatability. There was no support for H2 as neither leaf traits nor experi-
mentally estimated palatability affected the mean body mass of leaf chewers. The mean
body mass of rostrum chewers was positively related to palatability. Thus, leaf traits and
experimentally estimated palatability influenced the abundance and mean body mass of
chewing arthropods on the community level. However, the data were not consistent with the
Jarman-Bell principle. Overall, our results suggest that the palatability of leaves is not
among the dominant factors influencing abundance and mean body mass of the community of chewing arthropod herbivores. If other factors, such as the microclimate, predation or fur-
ther (a-)biotic interactions are more important has to be analyzed in refined studies.
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Keywords: |
insect herbivores |
abundance |
morphological traits |
leaf functional traits |
Jarman-Bell principle |
leaf chewers |
rostrum chewers |
palatability |
Rollenbeck, R.; Orellana-Alvear, J.; Bendix, J.; Rodriguez, R.; Pucha-Cofrep, F.; Guallpa, M.; Fries, A. & Celleri, R. (2022): The Coastal El Niño Event of 2017 in Ecuador and Peru: A Weather Radar Analysis. Remote Sensing 14(4), 824.
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.; Knüsting, 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), 1-1.
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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. Irre-
spective 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 rela-
tively 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 circum-
ference fluctuations. Nighttime transpiration and hydrological type: In contrast to the isohy-
drically performing trees of the Ocotea group, the anisohydric trees showed considerable
water vapour pressure deficit (VPD)-dependent nocturnal transpiration. Therefore, we con-
clude that nighttime ET at the forest level is mainly sourced by the tree species with aniso-
hydric performance.
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Keywords: |
dendrometer |
Evapotranspiration |
Sap flux |
Eddy covariance |
Muñoz, P.; Orellana-Alvear, J.; Bendix, J.; Feyen, J. & Celleri, R. (2021): Flood Early Warning Systems Using Machine Learning Techniques: The Case of the Tomebamba Catchment at the Southern Andes of Ecuador. Hydrology 8(4), -.
Wallis, C.; Tiede, Y.; Beck, E.; Boehning-Gaese, K.; Brandl, R.; Donoso, D.A.; Espinosa, C.; Fries, A.; Homeier, J.; Inclan, D.; Leuschner, C.; Maraun, M.; Mikolajewski, K.; Neuschulz, E.L.; Scheu, S.; Schleuning, M.; Suárez, J.P.; Tinoco, B.A.; Farwig, N. & Bendix, J. (2021): Biodiversity and ecosystem functions depend on environmental conditions and resources rather than the geodiversity of a tropical biodiversity hotspot. Scientific Reports 11(1), 24530.
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DOI: 10.1038/s41598-021-03488-1
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Abstract:
Abstract:
Biodiversity and ecosystem functions are highly threatened by global change. It has been proposed that geodiversity can be used as an easy-to-measure surrogate of biodiversity to guide conservation management. However, so far, there is mixed evidence to what extent geodiversity can predict biodiversity and ecosystem functions at the regional scale relevant for conservation planning. Here, we analyse how geodiversity computed as a compound index is suited to predict the diversity of four taxa and associated ecosystem functions in a tropical mountain hotspot of biodiversity and compare the results with the predictive power of environmental conditions and resources (climate, habitat, soil). We show that combinations of these environmental variables better explain species diversity and ecosystem functions than a geodiversity index and identified climate variables as more important predictors than habitat and soil variables, although the best predictors differ between taxa and functions. We conclude that a compound geodiversity index cannot be used as a single surrogate predictor for species diversity and ecosystem functions in tropical mountain rain forest ecosystems and is thus little suited to facilitate conservation management at the regional scale. Instead, both the selection and the combination of environmental variables are essential to guide conservation efforts to safeguard biodiversity and ecosystem functions.
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Keywords: |
Biodiversity |
geodiversity |
Velescu, A.; Homeier, J.; Bendix, J.; Valarezo, C. & Wilcke, W. (2021): Response of water-bound fluxes of potassium, calcium, magnesium and sodium to nutrient additions in an Ecuadorian tropical montane forest. Forest Ecology and Management 501(119661), 1-14.
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DOI: 10.1016/j.foreco.2021.119661
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Abstract:
Abstract:
In the past two decades, the Amazon-exposed, tropical montane rain forests in south Ecuador experienced increasing deposition of reactive N mainly from Amazonian forest fires, episodic Ca and Mg inputs from Saharan dust, and a low but constant P deposition from unknown sources. To explore the response of this tropical, perhumid ecosystem to nutrient inputs, we established in 2007 a Nutrient Manipulation Experiment (NUMEX). Since 2008, we have applied 50 kg ha−1 year−1 of N as urea, 10 kg ha−1 year−1 of P as NaH2PO4·H2O, 50 kg ha−1 year−1 of N + 10 kg ha−1 year−1 of P and 10 kg ha−1 year−1 of Ca as CaCl2·H2O in a randomized block design at 2000 m a.s.l. in a natural forest of the south Ecuadorian Andes. Previous studies have shown that alkali and alkaline earth metals had beneficial effects on the functioning of N and P co-limited tropical forests occurring on acidic soils. Therefore, we determined the response of all major aqueous ecosystem fluxes of K, Ca, Mg and Na to nutrient amendments, to understand how increasing atmospheric deposition would affect their cycling in the future. Additions of N and P decreased K leaching from the organic layer and in the mineral soil, thus tightening K cycling. This suggests that increasing future N and P availability may result in K limitation in the long term. The leaching of Ca and Mg from the canopy increased in response to amendments of N and P and we observed an enhanced uptake of these nutrients also if Ca was amended alone. Although N was applied as urea, acidity of soil solutions and leaching of K, Ca, Mg and Na did not increase following separate N amendments. In spite of the acid soils and of its low cation-exchange competitivity, Na included in the P fertilizer was only partly leached from the organic layer. We suggest that it was probably required to cover an unmet Na demand of the soil fauna. Our results demonstrate the major role in the functioning of the tropical montane forests played by K, Ca and Mg as potential future growth-limiting elements and increasingly required nutrients in response to rising N and P availability, while they also support the importance of Na as a functional element in these ecosystems.
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Keywords: |
Ecuador |
NUMEX |
nutrient manipulation |
tropical montane forest |
nutrient additions |
base cations |
Tiede, Y.; Hemp, C.; Schmidt, A.; Nauss, T.; Farwig, N. & Brandl, R. (2018): Beyond body size: consistent decrease of traits within orthopteran assemblages with elevation. Ecology 0(0), 1-13.
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DOI: 10.1002/ecy.2436
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Abstract:
Abstract:
Morphological traits provide the interface between species and their environment. For example, body size affects the fitness of individuals in various ways. Yet especially for ectotherms, the applicability of general rules of interspecific clines of body size and even more so of other morphological traits is still under debate. Here we tested relationships between elevation (as a proxy for temperature) and productivity with four ecologically relevant morphological traits of orthopteran assemblages that are related to fecundity (body size), dispersal (wing length), jumping ability (hind femur length), and predator detection (eye size). We measured traits of 160 orthopteran species that were sampled along an extensive environmental gradient at Mt. Kilimanjaro (Tanzania), spanning elevations from 790 to 4,410 m above sea level (a.s.l.) with different levels of plant productivity. For traits other than body size, we calculated the residuals from a regression on body length to estimate the variation of traits irrespective of body size. Bayesian analyses revealed that mean body size of assemblages, as well as the means of relative wing length, hind femur length, and eye size, decreased with increasing elevation. Body size and relative eye size also decreased with increasing productivity. Both phylogenetic relationships, as well as species‐specific adaptations, contributed to these patterns. Our results suggest that orthopteran assemblages had higher fecundity and better dispersal and escape abilities, as well as better predator detection at higher temperatures (low elevations) than at low temperatures (high elevations). Large body sizes might be advantageous in habitats with low productivity because of a reduced risk of starvation. Likewise, large eye size might be advantageous because of the ability to detect predators in habitats with low vegetation cover, where hiding possibilities are scarce. Our study highlights that changes in temperature and productivity not only lead to interspecific changes in body size but are also related to independent changes of other morphological traits that influence the ecological fit of organisms in their environment.
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Keywords: |
body size |
eleva |
morphological traits |
vegetation index |
productivity |
resource availability hypothesis |
Núñez, P.Á.; Silva, B.; Schulz, M.; Rollenbeck, R. & Bendix, J. (2021): Evapotranspiration estimates for two tropical mountain forest using high spatial resolution satellite data. International Journal of Remote Sensing 42(8), 2940--2962.
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DOI: 10.1080/01431161.2020.1864058
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Abstract:
Abstract:
Tropical Mountain Forest (TMF) provides important ecological functions like evapotranspiration (ET) that supplies moisture and energy to the atmosphere. ET observations are scarce and difficult to accomplish particularly in areas of high heterogeneity where TMF are. Remote sensing (RS) allows to quantify and to determine ET spatial variation at the landscape level. Detail imaginary improves high spatial variability retrieval. Thought the greater detail introduces cast shadows by trees which hamper image interpretation. The objective of this study is to characterize ET estimation for the TMF of the southern Ecuadorian Andes by combining meteorological data with high-resolution satellite images. Shadows from high resolution images were masked out by applying focal statistics. The analysis included two meteorological periods typical of the area; a wet period when rain prevails and a dry period when precipitation is more sporadic. The reference evapotranspiration (ET0) was calculated using the FAO-Penman Montheid method by applying data obtained from an automatic weather station. The enhanced vegetation index (EVI) was derived from 2 m resolution WorldView2 satellite images. Results showed a lower ET mean value during the wet period: 1.54 mm day−1 compared to 2.37 mm day−1. Two forest types, differentiated from its structural composition and topographical position (ravine and ridge), marked ET spatial variation. Ravine forest that has a more dense and closed canopy showed higher ET values for both meteorological conditions. A comparison between ET estimations and ET field measurements from a scintillometer device showed a good agreement (coefficient of correlation r = 0.89) that proves the validity of the method. This study demonstrates that the application of high spatial resolution improves ET estimation in TMF especially when shadows are removed. Also, emphasizes the importance of analysing spatial heterogeneity to properly assess ecosystem water flux terms.
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Keywords: |
remote sensing |
mountain rainforest |
Evapotranspiration |
Bogner, F.; Bendix, J. & Beck, E. 2019: El Bosque Tropical de Montaña - Hotspot de Biodiversidad. (Naturaleza y Cultura Internacional, (Loja, Ecuador).
Campozano, L.; Trachte, K.; Celleri, R.; Samaniego, E.; Bendix, J.; Cristóbal, A. & Mejia, J.F. (2018): Climatology and Teleconnections of Mesoscale Convective Systems in an Andean Basin in Southern Ecuador: The Case of the Paute Basin. Advances in Meteorology 2018, 1-13.
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DOI: 10.1155/2018/4259191
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Abstract:
Abstract:
Mesoscale convective systems (MCSs) climatology, the thermodynamic and dynamical variables, and teleconnections influencing MCSs development are assessed for the Paute basin (PB) in the Ecuadorian Andes from 2000 to 2009. The seasonality of MCSs occurrence shows a bimodal pattern, with higher occurrence during March-April (MA) and October-November (ON), analogous to the regional rainfall seasonality. The diurnal cycle of MCSs shows a clear nocturnal occurrence, especially during the MA and ON periods. Interestingly, despite the higher occurrence of MCSs during the rainy seasons, the monthly size relative frequency remains fairly constant throughout the year. On the east of the PB, the persistent high convective available potential and low convective inhibition values from midday to nighttime are likely related to the nocturnal development of the MCSs. A significant positive correlation between the MCSs occurrence to the west of the PB and the Trans-Niño index was found, suggesting that ENSO is an important source of interannual variability of MCSs frequency with increasing development of MCSs during warm ENSO phases. On the east of the PB, the variability of MCSs is positively correlated to the tropical Atlantic sea surface temperature anomalies south of the equator, due to the variability of the Atlantic subtropical anticyclone, showing main departures from this relation when anomalous conditions occur in the tropical Pacific due to ENSO.
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Keywords: |
Andes |
Meteorology |
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 |
carbon |
Paramo |
Evapotranspiration |
Tropical Andes |
Eddy covariance |
Knüsting, J.; Brinkmann, M.C.; Silva, B.; Schorsch, M.; Bendix, J.; Beck, E. & Scheibe, R. (2018): Who will win where and why? An ecophysiological dissection of the competition between a tropical pasture grass and the invasive weed Bracken over an elevation range of 1000m in the tropical Andes. PlosOne 13, 1-24.
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DOI: 10.1371/journal.pone.0202255
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Abstract:
Abstract:
In tropical agriculture, the vigorously growing Bracken fern causes severe problems by
invading pastures and out-competing the common pasture grasses. Due to infestation by
that weed, pastures are abandoned after a few years, and as a fatal consequence, the biodi-
versity-rich tropical forest is progressively cleared for new grazing areas. Here we present a
broad physiological comparison of the two plant species that are the main competitors on
the pastures in the tropical Ecuadorian Andes, the planted forage grass Setaria sphacelata
and the weed Bracken (Pteridium arachnoideum).With increasing elevation, the competitive
power of Bracken increases as shown by satellite data of the study region. Using data
obtained from field measurements, the annual biomass production of both plant species, as
a measure of their competitive strength, was modeled over an elevational gradient from
1800 to 2800 m. The model shows that with increasing elevation, biomass production of the
two species shifts in favor of Bracken which, above 1800 m, is capable of outgrowing the
grass. In greenhouse experiments, the effects on plant growth of the presumed key vari-
ables of the elevational gradient, temperature and UV radiation, were separately analyzed.
Low temperature, as well as UV irradiation, inhibited carbon uptake of the C4-grass more
than that of the C3-plant Bracken. The less temperature-sensitive photosynthesis of
Bracken and its effective protection from UV radiation contribute to the success of the weed
on the highland pastures. In field samples of Bracken but not of Setaria, the content of flavo-
noids as UV-scavengers increased with the elevation. Combining modeling with measure-
ments in greenhouse and field allowed to explain the invasive growth of a common weed in
upland pastures. The performance of Setaria decreases with elevation due to suboptimal
photosynthesis at lower temperatures and the inability to adapt its cellular UV screen.
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Keywords: |
South Ecuador |
Bracken fern |
competition |
Gonzales-Jaramillo, V.; Fries, A.; Zeilinger, J.; Homeier, J.; Paladines, J. & Bendix, J. (2018): Estimation of Above Ground Biomass in a Tropical Mountain Forest in Southern Ecuador Using Airborne LiDAR Data. Remote Sensing 10, .
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DOI: 10.3390/rs10050660
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Abstract:
Abstract:
A reliable estimation of Above Ground Biomass (AGB) in Tropical Mountain Forest (TMF)
is still complicated, due to fast-changing climate and topographic conditions, which modifies the
forest structure within fine scales. The variations in vertical and horizontal forest structure are hardly
detectable by small field plots, especially in natural TMF due to the high tree diversity and the
inaccessibility of remote areas. Therefore, the present approach used remotely sensed data from a
Light Detection and Ranging (LiDAR) sensor in combination with field measurements to estimate
AGB accurately for a catchment in the Andes of south-eastern Ecuador. From the LiDAR data,
information about horizontal and vertical structure of the TMF could be derived and the vegetation at
tree level classified, differentiated between the prevailing forest types (ravine forest, ridge forest and
Elfin Forest). Furthermore, topographical variables (Topographic Position Index, TPI; Morphometric
Protection Index, MPI) were calculated by means of the high-resolution LiDAR data to analyse the
AGB distribution within the catchment. The field measurements included different tree parameters
of the species present in the plots, which were used to determine the local mean Wood Density
(WD) as well as the specific height-diameter relationship to calculate AGB, applying regional scale
modelling at tree level. The results confirmed that field plot measurements alone cannot capture
completely the forest structure in TMF but in combination with high resolution LiDAR data, applying
a classification at tree level, the AGB amount (Mg ha??1) and its distribution in the entire catchment
could be estimated adequately (model accuracy at tree level: R2 > 0.91). It was found that the AGB
distribution is strongly related to ridges and depressions (TPI) and to the protection of the site (MPI),
because high AGB was also detected at higher elevations (up to 196.6 Mg ha??1, above 2700 m), if the
site is situated in depressions (ravine forest) and protected by the surrounding terrain. In general,
highest AGB is stored in the protected ravine TMF parts, also at higher elevations, which could only
be detected by means of the remote sensed data in high resolution, because most of these areas are
inaccessible. Other vegetation units, present in the study catchment (pasture and subpáramo) do not
contain large AGB stocks, which underlines the importance of intact natural forest stands.
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Keywords: |
LiDAR |
AGB estimation |
Beck, E.; Knoke, T.; Farwig, N.; Breuer, L.; Siddons, D. & Bendix, J. 2017: Landscape Restoration, Sustainable Land Use and Cross-scale Monitoring of Biodiversity and Ecosystem Functions. A Science-directed Approach for South Ecuador. (Universität Bayreuth).
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DOI: 10.5678/lcrs/pak823-825.cit.1696
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Abstract:
Abstract:
In 201 3, the “Platform for Biodiversity and Ecosystem
Monitoring and Research in South Ecuador”
(www.TropicalMountainForest.org) was launched as a
knowledge transfer program in the biodiversity
hotspot of the southern Ecuadorian Andes, jointly
funded by the German Research Foundation (DFG)
and Ecuadorian non-university partners. One of the
overall aims of the transdisciplinary program is to
design science-directed recommendations for an
ecologically sustainable, economically profitable and
socially compatible use of the mainly rural land. The
second major goal of the program is the development
of functional indicators that are crucial for the
monitoring of impacts of environmental change on the
ecosystem and its functions. They encompass
abiotic, abiotic-biotic and biotic-biotic interrelations,
and are sensitive - though to different extent - to
subtle changes in the environment. Therefore, it is not
only the interaction per se, which has to be examined.
In addition to that the quantification of the response to
certain environmental stressors is needed.
Representing the fundament of ecosystem functioning,
biodiversity as such or certain functional taxa can
be monitored for an assessment of the ecosystem’s
state. Important further criteria for the selection of an
indicator are general applicability, easiness of
handling and stability against pitfalls.
This book “Landscape Restoration, Sustainable
Use and Cross-scale Monitoring of Biodiversity
and Ecosystem Functions: A Science-directed
Approach for South Ecuador” presents in its first
part a compilation of sustainable land use concepts
that have been proven for application in the Provinces
Loja and Zamora Chinchipe and beyond, given
comparable environmental conditions. The second
part describes functional indicators as well as their
development, monitoring and application.
Both parts start with introductory chapters on the
major aims of the respective transdisciplinary
program, followed by contributions showing how land
use concepts can be used to achieve sustainable
management and ecosystem services, as well as how
functional indicators can be used to assess and
monitor the stability of biodiversity and ecosystem
functions.
It should be stressed that this book has not the aim to
present only a scientific summary of the developed
systems. Instead, it targets on stakeholders as our
non-university partners and beyond which are in
charge of environmental planning and ecosystem
function surveillance in Ecuador. In the manner of a
technical handbook, it gives a comprehensible introduction
to the land use option or the indicator,
followed by hints how to apply, implement and assess
the developed systems. The book is and was
complementing our three pillars of capacity building
which also includes stakeholder workshops on the
developed land use options and indicators, and
demonstration plots in the field.
With this book the authors highly acknowledge the
generous funding of the research by the German
Science Foundation (DFG) and the logistic,
administrative and practical support by the foundation
Naturaleza y Cultura Internacional (Loja and Del
Mar). Such research requires also fruitful
collaboration with local academic institutions, the
Universidad Tecnica Particular de Loja, the
Universidad Nacional de Loja, the Universidad de
Cuenca, the Universidad de Azuay, and the local
weather service INAMHI. These partnerships were a
great experience in capacity building on both sides,
as evidenced by a number of academic degrees
obtained and by numerous joint publications. The
authors are also grateful for the support of our nonuniversity
research partners beyond NCI, namely
ETAPA EP (Empresa Pública Municipal de
Telecomunicaciones, Agua potable, lcantarillado y
Saneamiento de Cuenca- Ecuador), the Gobierno
Municipal de Zamora and the regional water fund
FORAGUA (Fondo Regional del Agua). Further,
sincere thanks are owed to the Ecuadorian Ministry of
the Environment (MAE) for permission to conduct
research in South Ecuador.
The Editors
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Keywords: |
sustainable land use |
Cross-scale Monitoring |
science-directed guidelines |
landscape restoration |
Oñate-Valdivieso, F.; Fries, A.; Mendoza, K.; Gonzales-Jaramillo, V.; Pucha Cofrep, F.; Rollenbeck, R. & Bendix, J. (2017): Temporal and spatial analysis of precipitation patterns in an Andean region of southern Ecuador using LAWR weather radar. Meteorology and Atmospheric Physics 129(295), 1-12.
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DOI: 10.1007/s00703-017-0535-8
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Abstract:
Abstract:
This paper focuses on the analysis of precipitation patterns, using a Local Area Weather Radar to collect information about the precipitation distribution in an Andean region of southern Ecuador (cities of Loja, Zamora and Catamayo). 54 representative events were selected to develop daily precipitation maps and to obtain their relevant characteristics, which were related to the topography and the season. The results showed that a strong correlation between the areas covered by precipitation (RA coefficient) and the season exists. In general, humid air masses come from the east (Amazon Basin), but during the main rainy season (December to April), humidity also frequently enters the study region from the west (Pacific Ocean). The rainy season is characterized by convective precipitation, associated with higher evaporation rates during austral summer. The relatively dry season is formed between May and November, but considerable precipitation amounts are registered, too, due to advective moisture transport from the Amazon Basin, a result of the predominant tropical easterlies carrying the humidity up the eastern escarpment of the Andes, generally following the natural course of the drainage systems.
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Keywords: |
Ecuador |
precipitation |
radar |
Bendix, J.; Fries, A.; Zárate, J.; Trachte, K.; Rollenbeck, R.; Pucha Cofrep, F.; Paladines, R.; Palacios, I.; Orellana Alvear, J.; Oñate-Valdivieso, F.; Naranjo, C.; Mendoza, L.; Mejia, D.; Guallpa, M.; Gordillo, F.; Gonzales-Jaramillo, V.; Dobbermann, M.; Celleri, R.; Carrillo, C.; Araque, A. & Achilles, S. (2017): Radarnet Sur – first weather radar network in tropical high mountains. Bulletin of the American Meteorological Society 98(6), 1235-1254.
Silva, B.; Alava Núñez, P.; Strobl, S.; Beck, E. & Bendix, J. (2017): Area-wide evapotranspiration monitoring at the crown level of a tropical mountain rain forest. Remote Sensing of Environment 194, 219–229.
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DOI: 10.1016/j.rse.2017.03.023
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Abstract:
Abstract:
Ecosystem water regulation couples energy and water balance, depends on the integrity of the ecosystem, and responds to changes in climate. Changes in tree-water relationships in the biodiversity hotspot of the tropical Andes in southern Ecuador might be potentially observed at the level of individual trees, thus providing an efficient ecosystem monitoring method with applications in forest management and conservation at the tree and landscape levels. In this study, we combine area-average measurements from a laser scintillometer above the forest with optical satellite data at high spatial resolution to obtain area-wide evapotranspiration data. The processing of field data includes the calculation of energy storage in forest biomass and the partitioning of evapotranspiration into transpiration and evaporation. Satellite-based estimates are calibrated by using tower flux measurements and meteorological data within periods of humid and less-humid atmosphere. The annual evapotranspiration was 1316 mm, of which 1086 mm per year corresponds to the forest transpiration at the study site. Average values of 4.7 and 4.1 mm d-1 per tree crown are observed under humid and less-humid atmospheric conditions, respectively, when applying high-resolution area-wide evapotranspiration in individual crown analysis. Approximately 24% of the observed crowns show a positive monthly change in ET, and 51% of the crowns show a significant change in the daily ET, which can be considered sensitive individuals concerning water relationships. The limitations in the area-wide evapotranspiration at the crown level can be explained by considering the spectral responses of the crown individuals. The presented method can be robustly deployed in the ecological monitoring of mountain forests.
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Keywords: |
remote sensing |
Evapotranspiration |
crown scale |
Silva, B.; Álava-Núñez, P.; Strobl, S.; Beck, E. & Bendix, J. (2017): Area-wide evapotranspirationmonitoring at the crown level of a tropical mountain rain forest. Remote Sensing of Environment 194( ), 219-229.
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DOI: 10.1016/j.rse.2017.03.023
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Abstract:
Abstract:
Ecosystem water regulation couples energy and water balance, depends on the integrity of the ecosystem, and
responds to changes in climate. Changes in tree-water relationships in the biodiversity hotspot of the tropical
Andes in southern Ecuador might be potentially observed at the level of individual trees, thus providing an ef?-
cient ecosystem monitoring method with applications in forest management and conservation at the tree and
landscape levels. In this study,we combine area-averagemeasurements froma laser scintillometer above the for-
est with optical satellite data at high spatial resolution to obtain area-wide evapotranspiration data. The process-
ing of ?eld data includes the calculation of energy storage in forest biomass and the partitioning of
evapotranspiration into transpiration and evaporation. Satellite-based estimates are calibrated by using tower
?ux measurements and meteorological data within periods of humid and less-humid atmosphere. The annual
evapotranspiration was 1316 mm, of which 1086 mm per year corresponds to the forest transpiration at the
study site. Average values of 4.7 and 4.1 mm d?1
per tree crown are observed under humid and less-humid at-
mospheric conditions, respectively, when applying high-resolution area-wide evapotranspiration in individual
crown analysis. Approximately 24% of the observed crowns show a positive monthly change in ET, and 51% of
the crowns show a signi?cant change in the daily ET, which can be considered sensitive individuals concerning
water relationships. The limitations in the area-wide evapotranspiration at the crown level can be explained
by considering the spectral responses of the crown individuals. The presented method can be robustly deployed
in the ecological monitoring of mountain forests.
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Keywords: |
remote sensing |
Evapotranspiration |
crown scale |
Wallis, C.; Brehm, G.; Donoso, D.A.; Fiedler, K.; Homeier, J.; Paulsch, D.; Suessenbach, D.; Tiede, Y.; Brandl, R.; Farwig, N. & Bendix, J. (2017): Remote sensing improves prediction of tropical montane species diversity but performance differs among taxa. Ecological Indicators 1(1), 1-10.
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DOI: 10.1016/j.ecolind.2017.01.022
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Abstract:
Abstract:
Texture information from passive remote sensing images provides surrogates for habitat structure, which is relevant for modeling biodiversity across space and time and for developing effective ecological indicators. However, the applicability of this information might differ among taxa and diversity measures. We compared the ability of indicators developed from texture analysis of remotely sensed images to predict species richness and species turnover of six taxa (trees, pyraloid moths, geometrid moths, arctiinae moths, ants, and birds) in a megadiverse Andean mountain rainforest ecosystem. Partial least-squares regression models were fitted using 12 predictors that characterize the habitat and included three topographical metrics derived from a high-resolution digital elevation model and nine texture metrics derived from very high-resolution multi-spectral orthophotos. We calculated image textures derived from mean, correlation, and entropy statistics within a relatively broad moving window (102 m × 102 m) of the near infra-red band and two vegetation indices. The model performances of species richness were taxon dependent, with the lowest predictive power for arctiinae moths (4%) and the highest for ants (78%). Topographical metrics sufficiently modeled species richness of pyraloid moths and ants, while models for species richness of trees, geometrid moths, and birds benefited from texture metrics. When more complexity was added to the model such as additional texture statistics calculated from a smaller moving window (18 m × 18 m), the predictive power for trees and birds increased significantly from 12% to 22% and 13% to 27%, respectively. Gradients of species turnover, assessed by non-metric two-dimensional scaling (NMDS) of Bray-Curtis dissimilarities, allowed the construction of models with far higher predictability than species richness across all taxonomic groups, with predictability for the first response variable of species turnover ranging from 64% (birds) to 98% (trees) of the explained change in species composition, and predictability for the second response variable of species turnover ranging from 33% (trees) to 74% (pyraloid moths). The two NMDS axes effectively separated compositional change along the elevational gradient, explained by a combination of elevation and texture metrics, from more subtle, local changes in habitat structure surrogated by varying combinations of texture metrics. The application of indicators arising from texture analysis of remote sensing images differed among taxa and diversity measures. However, these habitat indicators improved predictions of species diversity measures of most taxa, and therefore, we highly recommend their use in biodiversity research.
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Keywords: |
moths |
species richness |
species turnover |
mountain rainforest |
tropical trees |
Birds |
ants |
orthophotos |
Tiede, Y.; Schlautmann, J.; Donoso, D.A.; Wallis, C.; Bendix, J.; Brandl, R. & Farwig, N. (2017): Ants as indicators of environmental change and ecosystem processes. Ecological indicators 1(1), 1-6.
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DOI: 10.1016/j.ecolind.2017.01.029
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Abstract:
Abstract:
Environmental stressors and changes in land use have led to rapid and dramatic species losses. As such, we need effective monitoring programs that alert us not only to biodiversity losses, but also to functional changes in species assemblages and associated ecosystem processes. Ants are important components of terrestrial food webs and a key group in food web interactions and numerous ecosystem processes. Their sensitive and rapid response to environmental changes suggests that they are a suitable indicator group for the monitoring of abiotic, biotic, and functional changes. We tested the suitability of the incidence (i.e. the sum of all species occurrences at 30 baits), species richness, and functional richness of ants as indicators of ecological responses to environmental change, forest degradation, and of the ecosystem process predation on herbivorous arthropods. We sampled data along an elevational gradient (1000–3000 m a.s.l.) and across seasons (wetter and drier period) in a montane rainforest in southern Ecuador. The incidence of ants declined with increasing elevation but did not change with forest degradation. Ant incidence was higher during the drier season. Species richness was highly correlated with incidence and showed comparable results. Functional richness also declined with increasing elevation and did not change with forest degradation. However, a null-model comparison revealed that the functional richness pattern did not differ from a pattern expected for ant assemblages with randomly distributed sets of traits across species. Predation on artificial caterpillars decreased along the elevational gradient; the pattern was not driven by elevation itself, but by ant incidence (or inter-changeable by ant richness), which positively affected predation. In spite of lower ant incidence (or ant richness), predation was higher during the wetter season and did not change with forest degradation and ant functional richness. We used path analysis to disentangle the causal relationships of the environmental factors temperature (with elevation as a proxy), season, and habitat degradation with the incidence and functional richness of ants, and their consequences for predation. Our results would suggest that the forecasted global warming might support more active and species-rich ant assemblages, which in turn would mediate increased predation on herbivorous arthropods. However, this prediction should be made with reservation, as it assumes that the dispersal of ants keeps pace with the climatic changes as well as a one-dimensional relationship between ants and predation within a food-web that comprises species interactions of much higher complexity. Our results also suggested that degraded forests in our study area might provide suitable habitat for epigaeic, ground-dwelling ant assemblages that do not differ in incidence, species richness, functional richness, composition, or predation on arthropods from assemblages of primary forests. Most importantly, our results suggest that the occurrence and activity of ants are important drivers of ecosystem processes and that changes in the incidence and richness of ants can be used as effective indicators of responses to temperature changes and of predation within mega-diverse forest ecosystems.
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Keywords: |
elevational gradient |
species traits |
forest degradation |
path model |
artificial caterpillars |
functional richness |
Farwig, N.; Bendix, J. & Beck, E. (2017): Introduction to the Special Issue “Functional monitoring in megadiverse tropical ecosystems”. Ecological indicators 1(1), 1-3.
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DOI: 10.1016/j.ecolind.2017.02.027
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Abstract:
Abstract:
Land-use and climate change are major threats to biodiversity and ecosystem functions. Most of the current biodiversity monitoring systems are based on periodic records of the populations of a set of threatened or popular ‘flagship’ indicator species. In contrast to the abundance-based monitoring of species, also specific indicators of processes and functional interactions in an ecosystem may become targets of a more functional monitoring which can unveil early responses of an ecosystem to environmental changes at different spatial and temporal scales. The contributions of this Special Issue present such functional indicators for assessing and predicting responses to environmental changes of ecosystem functions in a hotspot of tropical biodiversity.
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Keywords: |
Ecuador |
ecosystem services |
Biodiversity |
ecosystem functions |
global change effects |
functional monitoring systems |
Strobl, S.; Cueva, E.; Silva, B.; Knüsting, J.; Schorsch, M.; Scheibe, R.; Bendix, J. & Beck, E. (2016): Water relations and photosynthetic water use efficiency as indicators of slow climate change effects on trees in a tropical mountain forest in South Ecuador. Ecological Indicators xxx, xxx-xxx.
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DOI: 10.1016/j.ecolind.2016.12.021
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Abstract:
Abstract:
The effects of an increasing moisture on trees of the tropical species-rich mountain rain forest in the South Ecuadorian Andes was investigated, using the daily total water consumption (TWC) and the instantaneous water use efficiency (WUE, ratio of photosynthetic CO2 uptake per water loss by transpiration) as ecophysiological indicators. Two canopy and one sub-canopy tree species, (Vismia tomentosa, Clusiaceae, an as of yet unknown Lauracee, and Spirotheca rosea, Bombacaceae) were the experimental objects. Seasonal changes as well as a long-term (18 months) trend of increasing precipitation caused an inverse reaction of the TWC of the trees. Because of a rather unlimited water supply to the trees from a permanently high water content of the soil, transpiration followed mainly the atmospheric demand of water vapor, and increasing moisture hence reduced water loss by transpiration. It was hypothesized that in spite of the reduction in transpiratory water loss photosynthetic carbon acquisition would be not or less affected due to an increase in water use efficiency. Concomitant measurements of photosynthetic net CO2 uptake showed the expected increase of WUE in V. tomentosa and S. rosea, but no clear reaction of the Lauracee. Accompanying measurements of stem extension growth confirmed an undiminished growth of V. tomentosa and S. rosea but showed also suspended growth of the Lauracee during the wettest months. While TWC can be continuously monitored with the heat dissipation technique, WUE is determined by leaf porometry in campaigns for which access to the canopy is required. Simultaneous recordings of the gas exchange of leaves at 4 different positions in the crown of one of the experimental trees (V. tomentosa) showed the usability of the trait WUE in combination with the total daily water consumption as indicator set for assessing the response of trees to a subtly changing climate. However, not all tree species appear as likewise useful indicator trees.
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Keywords: |
tropical trees |
physiological indicators |
water and carbon relations |
water use efficiency |
long and short term monitoring |
Pérez Postigo, I.; Silva, B. & Bendix, J. (2015): Potential of Remotely Sensed Image Textures for Predicting Herbivory in the Ecuadorian Andes Fachbereich Philipps-Universität Marburg, Geographie , master thesis
Niepoth, A.; Bendix, J. & Kümmerle, T. (2015): Remote sensing based measures of tree diversity in the Southern Ecuadorian Andes Humboldt-Universität zu Berlin, Geographisches Institut, master thesis
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Abstract:
Abstract:
The South Ecuadorian Andes are one of the hottest global hotspots of biodiversity and currently threatened by land use and climate change. Forest structure and composition are crucial factors for understanding the capacity of forest support species in changing environments. In order to prioritize limited conservation resources a better understanding of tree diversity patterns is needed. The use of image texture measures, as a proxy for spatial and forest structure has shown useful possibilities in explaining patterns of tree diversity and species richness. My goal was to evaluate the performance of different texture measures on NDVI, EVI and two broad-band combinations on high resolution (0.3m) aerial photography to predict tree diversity. Bayesian Model Averaging (BMA) was used to relate in situ measurements of tree diversity to measures of image texture. Texture explained up to 44.7% of the variability of tree diversity with measures related to habitat heterogeneity, particularly variance, providing highest explanatory power. Image texture measures bear considerable potential for predicting tree diversity in the tropics and can contribute to improvements on conservation efforts and management planning.
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Keywords: |
remote sensing |
Biodiversity conservation |
tree species richness |
tropical trees |