Publications
Found 98 publication(s)
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Bogner, F. & Beck, E. 2024: Biodiversity Hotspot Tropical Seasonal Dry Forests.: 1. Auflage (Stiftung Schwarze Laber).
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 |
Zuidema, P.A.; Babst, F.; Groenendijk, P.; Trouet, V.; Abiyu, A.; Acuana-Soto, R.; Adenesky-Filho, E.; Alfaro-Sanchez, R.; Aragao, J.R.V.; Assis-Pereira, G.; Bai, X.; Barbosa, A.C.; Battipaglia, G.; Beeckman, H.; Botosso, P.C.; Bradley, T.; Bräuning, A.; Brienen, R.; Buckley, B.M.; Camarero, J.J.; Carvalho, A.; Ceccantini, G.; Centeno-Erguera, L.R.; Cerano-Paredes, J.; Chavez-Duran, A.A.; Cintra, B.B.L.; Cleaveland, M.K.; Couralet, C.; Arrigo, R.D.; Valle, J.I.; Dünisch, O.; Enquist, B.J.; Esemann-Quadros, K.; Eshetu, Z.; Fan, Z.; Ferrero, M.E.; Fichtler, E.; Fontana, C.; Francisco, K.S.; Gebrekirstos, A.; Gloor, E.; Granato-Souza, D.; Haneca, K.; Harley, G.L.; Heinrich, I.; Helle, G.; Inga, J.G.; Islam, M.; Jiang, Y.; Kaib, M.; Khamisi, Z.H.; Koprowski, M.; Kruijt, B.; Layme, E.; Leemans, R.; Leffler, A.J.; Lisi, C.S.; Loader, N.J.; Locosselli, G.M.; Lopez, L.; Lopez-Hernandez, M.I.; Lousada, J.L.P.C.; Mendivelso, H.A.; Mokria, M.; Montoia, V.R.; Moors, E.; Nabais, C.; Ngoma, J.; de Junior, F.C.N.; Oliveira, J.M.; Olmedo, G.M.; Pagotto, M.A.; Panthi, S.; Perez-De-Lis, G.; Pucha-Cofrep, D.; Pumijumnong, N.; Rahman, M.; Ramírez Correa, J.A.; Requena-Rojas, E.J.; de Ribeiro, A.S.; Robertson, I.; Roig, F.A.; Rubio-Camacho, E.A.; Sass-Klaassen, U.; Schöngart, J.; Sheppard, P.R.; Slotta, F.; Speer, J.H.; Therrell, M.D.; Toirambe, B.; Tomazello-Filho, M.; Torbenson, M.C.A.; Touchan, R.; Venegas-Gonzalez, A.; Villalba, R.; Villanueva-Diaz, J.; Vinya, R.; Vlam, M.; Wils, T. & Zhou, Z. (2022): Tropical tree growth driven by dry-season climate variability. Nature Geoscience 15, pages 269–276.
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 |
Bendix, J.; Aguirre, N.; Beck, E.; Bräuning, A.; Brandl, R.; Breuer, L.; Boehning-Gaese, K.; Dantas De Paula, M.; Hickler, T.; Homeier, J.; Inclan, D.; Leuschner, C.; Neuschulz, E.; Schleuning, M.; Suarez, J.P.; Trachte, K.; Wilcke, W. & Farwig, N. (2021): A research framework for projecting ecosystem change in highly diverse tropical mountain ecosystems. Oecologia 2021, 1-13.
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DOI: 10.1007/s00442-021-04852-8
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Abstract:
Abstract:
Tropical mountain ecosystems are threatened by climate and land-use changes. Their diversity and complexity make projec-
tions how they respond to environmental changes challenging. A suitable way are trait-based approaches, by distinguishing
between response traits that determine the resistance of species to environmental changes and efect traits that are relevant
for species’ interactions, biotic processes, and ecosystem functions. The combination of those approaches with land surface
models (LSM) linking the functional community composition to ecosystem functions provides new ways to project the
response of ecosystems to environmental changes. With the interdisciplinary project RESPECT, we propose a research
framework that uses a trait-based response-efect-framework (REF) to quantify relationships between abiotic conditions,
the diversity of functional traits in communities, and associated biotic processes, informing a biodiversity-LSM. We apply
the framework to a megadiverse tropical mountain forest. We use a plot design along an elevation and a land-use gradient
to collect data on abiotic drivers, functional traits, and biotic processes. We integrate these data to build the biodiversity-
LSM and illustrate how to test the model. REF results show that aboveground biomass production is not directly related to
changing climatic conditions, but indirectly through associated changes in functional traits. Herbivory is directly related to
changing abiotic conditions. The biodiversity-LSM informed by local functional trait and soil data improved the simulation
of biomass production substantially. We conclude that local data, also derived from previous projects (platform Ecuador), are
key elements of the research framework. We specify essential datasets to apply this framework to other mountain ecosystems.
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Keywords: |
Biodiversity-Land-Surface-Model |
Landshuter, N.; Mölg, T.; Grießinger, J.; Bräuning, A.; Peters, T. & Institute of Geography, F.E.E.G. (2020): Characteristics of moisture source regions and their potential effect on seasonal isotopic signatures of d18O in tropical trees of southern Ecuador. Frontiers in Earth Science 8(604804), 1-22.
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DOI: 10.3389/feart.2020.604804
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Abstract:
Abstract:
Ratios of stable oxygen isotopes in tree rings (δ18O) are a valuable proxy for reconstructing past climates. Such reconstructions allow us to gain better knowledge of climate dynamics under different (eg warmer) environmental conditions, which also forms the basis for effective risk management. The latter aspect is particularly relevant for our study site on the
western flanks of the Andes in Southern Ecuador, since the region is frequently affected by droughts and heavy precipitation events during the rainy season (January to April), leading to enormous social and economic losses. In particular, we focus on precipitation amounts and moisture source regions as they are known to influence the δ18O signature of tree rings. Moisture source regions are based on 240 h backward trajectories that were
calculated with the trajectory model LAGRANTO for the rainy seasons 2008 to 2017. A moisture source diagnostic was applied to the air parcel pathways. The resulting moisture source regions were analyzed by calculating composites based on precipitation amounts, season, and calendar year. The precipitation amounts were derived from data of a local Automatic Weather Station (AWS). The analysis confirms that our study site receives its moisture both, from the Atlantic and the Pacific Oceans.
Heavy precipitation events are linked to higher moisture contributions from the Pacific, and local SST anomalies along the coast of Ecuador are of higher importance than those off the coast toward the central Pacific. Moreover, we identified increasing moisture contributions from the Pacific over the course of the rainy season. This change and also rain amount
effects are detectable in preliminary data of δ18O variations in tree rings of Bursera graveolens. These signatures can be a starting point for investigating atmospheric and hydroclimatic processes, which trigger δ18O variations in tree rings, more extensively in future studies.
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Keywords: |
precipitation |
South Ecuador |
South America |
tropical trees |
Tree Rings |
modelling |
stable isotopes |
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.
Bogner, F.; Bendix, J. & Beck, E. 2019: El Bosque Tropical de Montaña - Hotspot de Biodiversidad. (Naturaleza y Cultura Internacional, (Loja, Ecuador).
Raffelsbauer, V.; Spannl, S.; Peña , K.; Pucha Cofrep, D.A.; Steppe, K. & Bräuning, A. (2019): Tree Circumference Changes and Species-Specific Growth Recovery After Extreme Dry Events in a Montane Rainforest in Southern Ecuador. Frontiers in Plant Sciences 10, 342.
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DOI: 10.3389/fpls.2019.00342
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Abstract:
Abstract:
Under drought conditions, even tropical rainforests might turn from carbon sinks to sources, and tree species composition might be altered by increased mortality. We monitored stem diameter variations of 40 tree individuals with stem diameters above 10 cm belonging to eleven different tree genera and three tree life forms with high-resolution dendrometers from July 2007 to November 2010 and additionally March 2015 to December 2017 in a tropical mountain rainforest in South Ecuador, a biodiversity hotspot with more than 300 different tree species belonging to different functional types. Although our study area receives around 2200 mm of annual rainfall, dry spells occur regularly during so-called “Veranillo del Niño” (VdN) periods in October-November. In climate change scenarios, droughts are expected with higher frequency and intensity as today. We selected dry intervals with a minimum of four consecutive days to examine how different tree species respond to drought stress, raising the question if some species are better adapted to a possible higher frequency and increasing duration of dry periods. We analyzed the averaged species-specific stem shrinkage rates and recovery times during and after dry periods. The two deciduous broadleaved species Cedrela montana and Handroanthus chrysanthus showed the biggest stem shrinkage of up to 2 mm after 10 consecutive dry days. A comparison of daily circumference changes over 600 consecutive days revealed different drought responses between the families concerning the percentage of days with stem shrinkage/increment, ranging from 27.5 to 72.5% for Graffenrieda emarginata to 45–55% for Podocarpus oleifolius under same climate conditions. Moreover, we found great difference of recovery times after longer-lasting (i.e., eight to ten days) VdN drought events between the two evergreen broadleaved species Vismia cavanillesiana and Tapirira guianensis. While Vismia replenished to pre-VdN stem circumference after only 5 days, Tapirira needed 52 days on average to restore its circumference. Hence, a higher frequency of droughts might increase inter-species competition and species-specific mortality and might finally alter the species composition of the ecosystem.
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Keywords: |
tree growth |
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 |
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 |
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 |
Butz, P.; Raffelsbauer, V.; Graefe, S.; Peters, T.; Cueva, E.; Hölscher, D. & Bräuning, A. (2016): Tree responses to moisture fluctuations in a neotropical dry forest as potential climate change indicators. Ecological Indicators 1(1), 1-13.
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DOI: 10.1016/j.ecolind.2016.11.021
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Abstract:
Abstract:
Trees in tropical dry forests (TDFs) have manifold drought coping strategies including succulence of different plant organs, wood anatomical traits and leaf phenology. As water availability to plants is the limiting factor for physiological activity, changes in precipitation patterns are assumed to have strong influences on tree phenology, growth and water turnover. Our objectives were to assess patterns in leaf phenology, radial stem circumference changes and sap flux responses to fluctuating moisture regimes of selected species. Based on these findings we evaluated the potential suitability as indicator species for climate change effects. The study was implemented at different elevational positions in a submontane dry forest of southern Ecuador. Annual rainfall is 600 mm with an eight months dry period; moisture availability slightly increases with altitude because of moist air coming from the Pacific. At three altitudes,we studied the tree species Ceiba trichistandra (leaf deciduous, stem succulent), Eriotheca ruizii (leaf deciduous, root succulent) and Erythrina velutina (leaf deciduous). Reversible stem swelling and shrinking was observed for all three species during the whole study period and at all positions at the altitudinal gradient. However, it was most pronounced and sensitive in the stem succulent C. trichistandra and at the lowest (driest) position. C. trichistandra flushed leaves at dry season intermittent rain events, and from dry to wet season leaf out was earlier, and in this period sap flux was high while stem circumference decreased. Length of the leaved periods of all species increased with altitude. Thus, clear differences among species, topographic positions, radial growth and tree water use patterns are revealed; especially C. trichistandra responded very sensitive to fluctuating moisture regimes with leaf phenology, sap flux and stem diameter variations, and can be regarded as a sensitive indicator for assessing climatic variations.
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Keywords: |
Ecuador |
Phenology |
Elevation gradient |
Sap flux |
Seasonality |
Tree indicator |
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 |
Bogner, F.; Bendix, J. & Beck, E. 2016: Biodiversity Hotspot - Tropical Mountain Rainforest. (NCI Foundation, Ecuador).
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DOI: 10.5678/lcrs/pak823-825.cit.1513
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Abstract:
Abstract:
In 2008, a booklet “The Mountain Rainforest: Scientific Discoveries in a Highly Diverse Eco - system in Southern Ecuador” was published by a German Research Unit, informing the public about 10 years of biodiversity and ecosystem research in the Eastern range of the tropical Andes of Ecuador. The authors (K. Kiss & A. Bräuning) had compiled 14 contributions on diversity, dynamic processes and potential use of the primary forest and of its agricultural replacement systems. Another 8 years of research in the area have immensely widened the understanding of the ecosystem and its value for science in general and for the region in particular. The new book “Biodiversity Hotspot: Tropical Mountain Rainforest”, starting with an introductory chapter on the research area as the second hottest biodiversity hotspot worldwide, presents in an apprehensible way the major results of 16 collaborative projects addressing questions of basic as well as applied research. Understanding ecosystem components and processes is the prerequisite for an assessment of its stability under climate and land use changes. With this book the authors acknowledge the long-standing support of the work by the German Research Foundation and by the foundation Naturaleza y Cultura Internacional in Loja and San Diego, as well as the fruitful collaboration with our Ecuadorian partners, the Universidad Tecnica Particular de Loja, the Universidad Nacional de Loja, the Universidad de Cuenca and the Universidad de Azuay, and the local weather service INAMHI. We also appreciate very much the important contributions of our non-university research partners beyond NCI, ETAPA EP (Empresa Pública Municipal de Telecomunicaciones, Agua potable, lcantarillado y Saneamiento de Cuenca - Ecuador), Gobierno Municipal de Zamora and the regional water fund FORAGUA (Fondo Regional del Agua).
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Keywords: |
Ecuador |
biodiversity hotspots |
Bendix, J. & Beck, E. (2016): Environmental Change And Its Impacts In A Biodiversity Hotspot Of The South Ecuadorian Andes–Monitoring And Mitigation Strategies. Erdkunde 70(1), 1-4.
Silva, B.; Strobl, S.; Beck, E. & Bendix, J. (2016): Canopy evapotranspiration, leaf transpiration and water use efficiency of an Andean pasture in SE-Ecuador – a case study. Erdkunde 70(1), 5-18.
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DOI: 10.3112/erdkunde.2016.01.02
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Abstract:
Abstract:
The relationship between canopy-level evapotranspiration (ETSci) and leaf-level transpiration (Tleaf) as well as photosynthesis (Pleaf) for a homogeneous tropical montane pasture was analyzed over five days using a combination of methods involving a laser scintillometer and a porometer. Weather conditions ranged from overcast to sunny during the period of study. The gas exchange of the leaves of the dominant pasture grass Setaria sphacelata (transpiration vs. photosyn¬thetic CO2 net uptake ) was measured with a porometer and physiologically interpreted on the background of microclimate variables (photosynthetic active radiation (PAR) as proxy for total light intensity, temperature, water vapor deficit of the air) and soil moisture data. Water use efficiency (WUE, photosynthetic CO2 net uptake vs water loss by leaf transpiration) of the pasture was used to analyze the grass’ range of response to the environmental variables of the research area. PAR and water vapor deficit of the air (VPD) appeared to be the determinant factors for Tleaf and ETSci. WUE for the Setaria sphacelata pasture ranged from 1.9 to 5.8 ?mol CO2 mmol-1 H20 day-1 and is particularly low during periods of high VPD combined with enhanced insolation during cloudless periods. ET measurements collected by the scintillometer demonstrated a strong correlation with water flux calculated using the Penman-Monteith approach (TPM) (r² = 0.95). Also, Tleaf measured with the porometer showed reasonable coincidence with the ET observations (r² = 0.78). Values of ETSci ranged from 2.26 to 4.96 mm day-1 and Tleaf ranged from 0.83 to 2.41 mm day-1, but only ETSci showed good correspondence with the available energy (net radiation). The lower correlation between Tleaf and canopy-level ETSci compared to that between ETSci and TPM was tested against contaminations from the adjacent fetch area of the scintillometer path, but no effects were found. Likewise, soil water limitations of Tleaf could be ruled out. Therefore, different correlations of ETSci and Tleaf with the incoming energy and VPD may be traced back to a direct effect of the VPD on ET in contrast to its indirect effect on Tleaf which is additionally regulated by physiological processes in the leaf stomata.
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Keywords: |
Porometry |
Setaria |
Evapotranspiration |
scintillometry |
Wagner, F.H.; Bräuning, A.; Homeier, J.; Spannl, S.; Volland, F. & et, a. (2016): Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests. Biogeosciences 13, 2537–2562.
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DOI: 10.5194/bg-13-2537-2016
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Abstract:
Abstract:
The seasonal climate drivers of the carbon cycle
in tropical forests remain poorly known, although these
forests account for more carbon assimilation and storage than
any other terrestrial ecosystem. Based on a unique combination
of seasonal pan-tropical data sets from 89 experimental
sites (68 include aboveground wood productivity measurements
and 35 litter productivity measurements), their associated
canopy photosynthetic capacity (enhanced vegetation
index, EVI) and climate, we ask how carbon assimilation
and aboveground allocation are related to climate seasonality
in tropical forests and how they interact in the seasonal
carbon cycle. We found that canopy photosynthetic capacity
seasonality responds positively to precipitation when rainfall
is < 2000mm/yr (water-limited forests) and to radiation
otherwise (light-limited forests). On the other hand, independent
of climate limitations, wood productivity and litterfall
are driven by seasonal variation in precipitation and
evapotranspiration, respectively. Consequently, light-limited
forests present an asynchronism between canopy photosynthetic
capacity and wood productivity. First-order control by
precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall < 2000mm/yr.
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Keywords: |
climate |
tree growth |
litterfall |
Knoke, T.; Paul, C.; Hildebrandt, P.; Calvas, B.; Castro, L.M.; Härtl, F.; Döllerer, M.; Hamer, U.; Windhorst, D.; Wiersma, Y.; Curatola Fernández, G.F.; Obermeier, W.A.; Adams, J.; Breuer, L.; Mosandl, R.; Beck, E.; Weber, M.; Stimm, B.; Haber, W.; Fürst, C. & Bendix, J. (2016): Compositional diversity of rehabilitated tropical lands supports multiple ecosystem services and buffers uncertainties. Nature Communications 7, Article number:11877.
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DOI: 10.1038/ncomms11877
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Abstract:
Abstract:
High landscape diversity is assumed to increase the number and level of ecosystem services. However, the interactions between ecosystem service provision, disturbance and landscape composition are poorly understood. Here we present a novel approach to include uncertainty in the optimization of land allocation for improving the provision of multiple ecosystem services. We refer to the rehabilitation of abandoned agricultural lands in Ecuador including two types of both afforestation and pasture rehabilitation, together with a succession option. Our results show that high compositional landscape diversity supports multiple ecosystem services (multifunction effect). This implicitly provides a buffer against uncertainty. Our work shows that active integration of uncertainty is only important when optimizing single or highly correlated ecosystem services and that the multifunction effect on landscape diversity is stronger than the uncertainty effect. This is an important insight to support a land-use planning based on ecosystem services.
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Keywords: |
ecosystem services |
South Ecuador |
sustainable land use |
land use modeling |
restoration |
Spannl, S.; Volland, F.; Pucha Cofrep, D.A.; Peters, T.; Cueva, E. & Bräuning, A. (2016): Climate variability, tree increment patterns and ENSO-related carbon sequestration reduction of the tropical dry forest species Loxopterygium huasango of Southern Ecuador. Trees Structure and Function e(e), e.
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DOI: DOI 10.1007/s00468-016-1362-0
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Abstract:
Abstract:
We present the first multi-year long time series
of local climate data in the seasonally dry tropical forest in
Southern Ecuador and related growth dynamics of Loxopterygium
huasango, a deciduous tree species. Local climate
was investigated by installing an automatically
weather station in 2007 and the daily tree growth variability
was measured with high-resolution point dendrometers.
The climatic impact on growth behaviour was
evaluated. Hydro-climatic variables, like precipitation and
relative humidity, were the most important factors for
controlling tree growth. Changes in rainwater input affected
radial increment rates and daily amplitudes of stem
diameter variations within the study period from 2009 to
2013. El Nin˜o Southern Oscillation (ENSO) related
variations of tropical Pacific Ocean sea surface temperatures
influenced the trees’ increment rates. Average radial
increments showed high inter-annual (up to 7.89 mm) and
inter-individual (up to 3.88 mm) variations. Daily amplitudes
of stem diameter variations differed strongly between
the two extreme years 2009 (wet) and 2011 (dry). Contrary
to 2009, the La Nin˜a drought in 2011 caused a rapid
reduction of the daily amplitudes, indicating a total cessation
(‘growth collapse’) of stem increment under ENSOrelated
drought conditions and demonstrating the high
impact of climatic extreme events on carbon sequestration
of the dry tropical forest ecosystem.
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Keywords: |
Ecuador |
dendrometer |
dendroecology |
Climate variability |
La Nina drought |
Seasonally dry tropical forest |
Spannl, S.; Homeier, J. & Bräuning, A. (2016): Nutrient-Induced Modifications of Wood Anatomical Traits of Alchornea lojaensis (Euphorbiaceae). Frontiers in Earth Science 4(50), 1-11.
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DOI: 10.3389/feart.2016.00050
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Abstract:
Abstract:
Regarding woody plant responses on higher atmospheric inputs of the macronutrients nitrogen (N) and phosphorous (P) on tropical forests in the future, an adaptive modification of wood anatomical traits on the cellular level of woody plants is expected. As part of an interdisciplinary nutrient manipulation experiment (NUMEX) carried out in Southern Ecuador, we present here the first descriptive and quantitative wood anatomical analysis of the tropical evergreen tree species Alchornea lojaensis (Euphorbiaceae). We sampled branch wood of nine individual trees belonging to treatments with N fertilization, N+P fertilization, and a control group, respectively. Quantitative evaluations of eleven different vessel parameters were conducted. The results showed that this endemic tree species will be able to adapt well to the future effects of climate change and higher nutrient deposition. This was firstly implied by an increase in vessel diameter and consequently a higher theo. area-specific hydraulic conductivity with higher nutrient availability. Secondly, the percentage of small vessels (0–20 ?m diameter) strongly increased with fertilization. Thirdly, the vessel arrangement (solitary vessels vs. multiple vessel groupings) changed toward a lower percentage of solitary vessel fraction (VS), and concurrently toward a higher total vessel grouping index (VG) and a higher mean group size of non-solitary vessels (VM) after N and N+P addition. We conclude that higher nutrient availability of N and N+P triggered higher foliage amount and water demand, leading to higher cavitation risk in larger vessels. This is counteracted by a stronger grouping of vessels with smaller risk of cavitation to ensure water supply during drier periods that are expected to occur in higher frequency in the near future.
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Keywords: |
fertilization |
branch wood |
evergreen tropical montane forest |
Euphorbiaceae |
quantitative wood anatomy |
Pucha Cofrep, D.A.; Peters, T. & Bräuning, A. (2015): Wet season precipitation during the past 120 years reconstructed from tree rings of a tropical dry forest in Southern Ecuador. Global and Planetary Change 133, 65–78.
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DOI: 10.1016/j.gloplacha.2015.08.003
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Abstract:
Abstract:
From 10 selected tree species, Bursera graveolens and Maclura tinctoria exhibited distinct annual and crossdatable tree-rings. It was possible to synchronize individual tree-ring series and to establish two tree-ring chronologies of 203 and 87 years length, respectively. The characteristic ENSO frequency band is reflected in wavelet
power spectra of both chronologies. Both species showa strong correlation between ringwidth and precipitation of thewet season (January–May). Strong El Niño events (1972, 1983 and 1998) lead to strong growth responses in the tree-ring chronologies, whereas ‘normal’ ENSO events do not trigger long-lasting growth responses. The first ring-width based wet-season precipitation reconstruction for the past 103 years was developed. Statistical and spatial correlation analysis verified the skills of the reconstructed precipitation which captures a great part of the Rainfall Index over the land area of Ecuador and the equatorial Pacific. Furthermore, teleconnections with central Pacific precipitation and SST patterns were found.
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Keywords: |
Ecuador |
precipitation |
tree growth |
wood anatomy |
dendroecology |
el nino |
ENSO |
tree rings |
dendrochronology |
dry forest |
Spannl, S.; Günter, S.; Peters, T.; Volland, F. & Bräuning, A. (2012): Which factors control tree growth in a tropical mountain forest? The case of Cedrela montana in Southern Ecuador. TRACE - Tree Rings in Archaeology, Climatology and Ecology 10, 99-105.
Spannl, S.; Ganzhi, O.; Peters, T. & Bräuning, A. (2013): Tree growth under climatic and trophic forcing - A nutrient manipulation experiment in Southern Ecuador. TRACE - Tree Rings in Archaeology, Climatology and Ecology 11, 10-14.
Rodriguez, F.; Bräuning, A.; Gerique, A.; Behling, H. & Volland, F. (2013): Landscape History, Vegetation History and Past Human Impacts. In: Bendix, J., Beck, E., Bräuning, A., Makeschin, F., Mosandl, R., Scheu, S., Wilcke, W. (eds.): Ecosystem Services, Biodiversity and Environmental Change in a Tropical Mountain Ecosystem of South ( 221), Springer, 53-66.
Knoke, T.; Bendix, J.; Pohle, P.; Hamer, U.; Hildebrandt, P.; Roos, K.; Gerique, A.; Lopez Sandoval, M.F.; Breuer, L.; Tischer, A.; Silva, B.; Calvas, B.; Aguirre, N.; Castro, L.M.; Windhorst, D.; Weber, M.; Stimm, B.; Günter, S.; Palomeque, X.; Mora, J.; Mosandl, R. & Beck, E. (2014): Afforestation or intense pasturing improve the ecological and economic value of abandoned tropical farmlands. Nature Communications 5:5612, 1-50.
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DOI: 10.1038/ncomms6612
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Abstract:
Abstract:
Increasing demands for livelihood resources in tropical rural areas have led to progressive
clearing of biodiverse natural forests. Restoration of abandoned farmlands could counter
this process. However, as aims and modes of restoration differ in their ecological and
socio-economic value, the assessment of achievable ecosystem functions and bene?ts
requires holistic investigation. Here we combine the results from multidisciplinary research
for a unique assessment based on a normalization of 23 ecological, economic and social
indicators for four restoration options in the tropical Andes of Ecuador. A comparison of the
outcomes among afforestation with native alder or exotic pine, pasture restoration with either
low-input or intense management and the abandoned status quo shows that both variants of
afforestation and intense pasture use improve the ecological value, but low-input pasture
does not. Economic indicators favour either afforestation or intense pasturing. Both Mestizo
and indigenous Saraguro settlers are more inclined to opt for afforestation.
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Keywords: |
sustainable land-use |
Silva, B.; Roos, K.; Fries, A.; Rollenbeck, R.; Beck, E. & Bendix, J. (2014): Mapping Two Competing Grassland Species from a Low-Altitude Helium Balloon. IEEE Journal of selected topics in applied earth observations and remote sensing 7(7), 3038 - 3049.
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DOI: 10.1109/JSTARS.2014.2321896
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Abstract:
Abstract:
This paper describes a method of low-altitude remote
sensing in combination with in situ measurements (leaf area, spectroscopy, and position) to monitor the postfire canopy recovery of two competing grassland species. The method was developed in the Andes of Ecuador, where a tethered balloon with a digital camera was deployed to record a time series of very high spatial resolution
imagery ( nominal resolution = 2cm ) of an experimental plot covered by two competing species: 1) the pasture grass, Setaria sphacelata; and 2) the invasive southern bracken, Pteridium arachnoideum. Image processing techniques were combined to solve geometric issues and construct high-quality mosaics for image classification. The semiautomatic and object-oriented classification method was based on geometrical and textural attributes of image segments and showed promising results for detecting the invasive bracken fern in Setaria pastures (performance by area under the curve, AUC = 0.88). Valuable insights are given into vegetation monitoring applications using unmanned aerial vehicles, which produces a time series of species-specific maps, including foliage projective cover (FPC) and leaf area index (LAI). This new method constitutes an important and accessible tool for ecological investigations of competing species in pastures and validation of remote sensing information on mountain environments.
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Keywords: |
bracken |
pasture |
land cover |
LAI |
remote sensing |
abandoned pasture |
burning |
Bracken fern |