Publications
Found 517 publication(s)
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Alvarez Figueroa, P.A.; Velescu, A.; Pierick, K. & Homeier, J. (2024): Sources and sinks of N in ecosystem solutions along the water path through a tropical montane forest in Ecuador assessed with δ15N values of total dissolved nitrogen. Journal of Geophysical Research: Biogeosciences 129, e2024JG008, 1-16.
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DOI: 10.1029/2024JG008043
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Abstract:
Abstract:
The globally increasing reactive N richness affects even remote ecosystems such as the tropical montane forests in Ecuador. We tested whether the δ15N values of total dissolved N (TDN), measured directly in solution with a TOC‐IRMS, can be used to help elucidate N sources and sinks along the water path and thus might be suitable for ecosystem monitoring. From 2013 to 2016, the δ15N values of TDN in bulk deposition showed the most pronounced temporal variation of all ecosystem solutions (δ15N values: 1.9–5.9‰). In throughfall (TF), TDN was on average 15N‐depleted (-1.8 ± s.d. 0.4‰) relative to rainfall (3.4 ± 0.9‰), resulting from net retention of isotopically heavy N, mainly as NH4+. Simultaneously, N‐isotopically light NO3‐N and dissolved organic nitrogen (DON) with a δ15N value between NO3‐N and NH4‐N were leached from the canopy (leaves: -3.5 ± 0.5‰). The increasing δ15N values in the order, TF < stemflow (SF, 0.1 ± 0.6‰) < litter leachate (LL, 1.3 ± 0.7‰) concurred with an increasing DON contribution to TDN reflecting the δ15N value of the organic layer (1.9 ± 0.9‰). The lower δ15N value of the mineral soil solution at the 0.15 m soil depth (SS15, -1.5 ± 0.3‰) than in LL can be explained by the retention of DON and NH4+ and the addition of NO3- from mineralization and nitrification. The increasing δ15N values in the order, SS15 < SS30 (-0.6 ± 0.2‰) < streamflow (ST, 0.5 ± 0.6‰) suggested gaseous N losses because of increasing denitrification. There was no seasonality of the δ15N values. Our results demonstrate that the δ15N values of TDN in ecosystem solutions help identify N sources and sinks in forest ecosystems.
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Keywords: |
throughfall |
15N natural abundance |
rainfall |
litter leachate |
time series |
Werner, F.A. & Homeier, J. (2024): Diverging elevational patterns of tree vs. epiphyte species density, beta diversity, and biomass in a tropical dry forest . Plants 13(18), 2555.
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DOI: 10.3390/plants13182555
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Abstract:
Abstract:
There is evidence to suggest that vascular epiphytes experience low competition for resources (light, water, and nutrients) compared to terrestrial plants. We tested the hypothesis that low resource competition may lead to higher nestedness among vascular epiphyte assemblages compared to trees. We studied the species composition and biomass of epiphytes and trees along an elevation gradient in a tropical dry forest in SW Ecuador. Both life-forms were inventoried on 25 plots of 400 m2 across five elevation levels (550–1250 m). Tree species density and total species richness increased with elevation, whereas basal area and biomass did not show significant trends. Epiphyte species density and richness both increased strongly with elevation, in parallel to biomass. Plot-level compositional changes were similarly strong for both life-forms. We attribute elevational increases in the species richness of trees and epiphytes to increasing humidity, i.e., more mesic growth conditions. We attribute the more pronounced elevational increase in epiphyte biomass, species density, and richness—the latter coupled with a higher degree of nestedness—to the greater moisture dependency of epiphytes and relatively low direct competition for resources. Our study provides a first comparison of elevational trends in epiphyte and tree diversity and biomass for a tropical dry forest.
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Keywords: |
biomass |
beta diversity |
species turnover |
Alpha diversity |
competition |
biotic interactions |
Martins, L.P.; Stouffer, D.B.; Boehning-Gaese, K.; Quitian, M.; Neuschulz, E.L.; Santillan, V.; Schleuning, M.; Many, M. & Tylianakis, J.M. (2024): Birds optimize fruit size consumed near their geographic range limits. Science 386, 331–336.
Martins, L.P.; Stouffer, D.B.; Boehning-Gaese, K.; Neuschulz, E.L.; Quitian, M.; Santillan, V.; Schleuning, M.; Many, M. & Tylianakis, J.M. (2022): Global and regional ecological boundaries explain abrupt spatial discontinuities in avian frugivory interactions. Nature Communications 13, 6943.
Marjakangas, E.; Munoz, G.; Turney, S.; Albrecht, J.; Neuschulz, E.L.; Schleuning, M. & Lessard, J. (2021): Trait-based inference of ecological network assembly: A conceptual framework and methodological toolbox. Ecological Monographs 92:e1502, 1-20.
Barczyk, M.; Acosta Rojas, D.C.; Espinosa, C.I.; Homeier, J.; Tinoco, B.A.; Velescu, A.; Wilcke, W.; Schleuning, M. & Neuschulz, E.L. (2024): Environmental conditions differently shape leaf, seed and seedling trait composition between and within elevations of tropical montane forests. Oikos e10421, 0-10.
Báez, S.; Cayuela, L.; Macia, M.; Alvarez-Dávila, E.; Apaza-Quevedo, A.; Arnelas, I.; Baca-Cortes, N.; Banares de Dios, G.; Bauters, M.; Ben Saadi, S.; Blundo, C.; Cabrera, M.; Castano, F.; Cayola, L.; de Aledo, J.; Espinosa, C.I.; Fadrique, B.; Farfan-Rios, W.; Fuentes, A.; Garnica-Diaz, C.; Gonzalez, M.; Gonzalez, D.; Hensen, I.; Hurtado, A.B.; Jadan, O.; Lippok, D.; Loza, M.; Maldonado, C.; Malizia, L.; Matas-Granados, L.; Myers, J.; Norden, N.; Oliveras Menor, I.; Pierick, K.; Ramirez-Angulo, H.; Salgado-Negret, B.; Schleuning, M.; Silman, M.; Solarte-Cruz, M.; Tello, J.; Verbeeck, H.; Vilanova, E.; Weithmann, G. & Homeier, J. (2022): FunAndes – A functional trait database of Andean plants. Scientific Data 9, 511.
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DOI: 10.1038/s41597-022-01626-6
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Abstract:
Abstract:
We introduce the FunAndes database, a compilation of functional trait data for the Andean flora spanning six countries. FunAndes contains data on 24 traits across 2,694 taxa, for a total of 105,466 entries. The database features plant-morphological attributes including growth form, and leaf, stem, and wood traits measured at the species or individual level, together with geographic metadata (i.e., coordinates and elevation). FunAndes follows the field names, trait descriptions and units of measurement of the TRY database. It is currently available in open access in the FIGSHARE data repository, and will be part of TRY’s next release. Open access trait data from Andean plants will contribute to ecological research in the region, the most species rich terrestrial biodiversity hotspot.
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Keywords: |
Andes |
plant functional traits |
Calvas, B.; Castro, L.M.; Kindu, M.; Bingham, L.; Pintado, K.; Torres Celi, J.; Knoke, T. & Cueva Ortiz, J.L. (2024): Large differences between observed and expected Ecuadorian deforestation from 2001 to 2009: a counterfactual simulation approach. Regional Environmental Change 24, 94.
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DOI: 10.1007/s10113-024-02253-0
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Abstract:
Abstract:
Ensuring the integrity of the world’s forests is indispensable for mitigating climate change, combatting biodiversity loss, and protecting the livelihoods of rural communities. While many strategies have been developed to address deforestation across different geographic scales, measuring their impact against a fluctuating background of market-driven forest loss is notoriously challenging. In this article, we (1) asses deforestation in Ecuador using a dynamic, counterfactual baseline that excludes non-market factors, (2) identify periods of reduced and excess deforestation, and (3) assess the economic consequences
of associated CO2 emissions using the social cost of carbon metric. We construct a counterfactual market-forces-only reference scenario by simulating heterogeneous profit-seeking agents making satisficing land-use allocation decisions under uncertainty. The model simulates a reference scenario for 2001–2022, a period encompassing dollarization, the beginning of a constitution granting inalienable rights to nature, and the launch of the largest payments for ecosystem services program in Ecuador’s history. On this period, total deforestation was approximately 20% lower than expected in a market-forces-only
scenario (9540 vs.12,000 km2). The largest deviation occurred in 2001–2009, when observed deforestation was 43.6% lower than expected (3720 vs 6590 km2).
From 2010 onwards, deforestation appears to be market-driven. We assess the economic value of avoided CO2 emissions at US $5.7 billion if the reduction is permanent, or US $3.1 billion considering a 1% risk of loss from 2022 onwards. We discuss contributing factors that likely shaped periods of reduced and excess deforestation and stress the need to use realistic baselines.
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Keywords: |
land use |
land use change |
land use modeling |
Ecuador, Climate Change, Land Use |
land use/land cover |
Barczyk, M.; Acosta Rojas, D.C.; Espinosa, C.I.; Schleuning, M. & Neuschulz, E.L. (2024): Seedling recruitment of small-seeded and large-seeded species in forests and pastures in southern Ecuador. Basic and Applied Ecology 75, 44-52.
Acosta Rojas, D.C.; Barczyk, M.; Espinosa, C.I.; Tinoco, B.A.; Neuschulz, E.L. & Schleuning, M. (2024): Systematic reduction in seed rain of large-seeded and endozoochorous species in pastures compared to forests along a tropical elevational gradient. Applied Vegetation Science 27, e12780.
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.
Guillen Otero, T.; Kessler, M. & Homeier, J. (2024): Fern mycorrhizae do not respond to fertilization in a tropical montane forest. Plant-Environment Interactions 5(2), e10139.
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DOI: 10.1002/pei3.10139
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Abstract:
Abstract:
Ferns are known to have a lower incidence of mycorrhization than angiosperms. It
has been suggested that this results from carbon being more limiting to fern growth
than nutrient availability, but this assertion has not been tested yet. In the present
study, we took advantage of a fertilization experiment with nitrogen and phosphorus
on cloud forest plots of the Ecuadorean Andes for 15 years. A previous analysis
revealed changes in the abundances of fern species in the fertilized plots compared
to the control plots and hypothesized that this might be related to the responses of
the mycorrhizal relationships to nutrient availability. We revisited the plots to assess
the root-associated
fungal communities of two epiphytic and two terrestrial fern
species that showed shifts in abundance. We sampled and analyzed the roots of 125
individuals following a metabarcoding approach. We recovered 1382 fungal ASVs, with
a dominance of members of Tremellales (Basidiomycota) and Heliotales (Ascomycota).
The fungal diversity was highly partitioned with little overlap between individuals. We
found marked differences between terrestrial and epiphytic species, with the latter
fundamentally missing arbuscular mycorrhizal fungi (AMF). We found no effect of
fertilization on the diversity or relative abundance of the fungal assemblages. Still, we
observed a direct impact of phosphorus fertilization on its concentration in the fern
leaves. We conclude that fern–fungi relationships in the study site are not restricted
by nutrient availability and suggest the existence of little specificity on the fungal
partners relative to the host fern species.
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Keywords: |
Ecuador |
nitrogen |
phosphorus |
fertilization |
Arbuscular mycorrhizal fungi |
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.
Laughlin, D.; Siefert, A.; Fleri, J.; Tumber-Davila, S.; Hammond, W.; Sabatini, F.; Damasceno, G.; Aubin, I.; Field, R.; Hatim, M.; Jansen, S.; Lenoir, J.; Lens, F.; McCarthy, J.; Niinemets, Ü.; Phillips, O.; Attorre, F.; Bergeron, Y.; Bruun, H.; Byun, C.; Custerevska, R.; Dengler, J.; De Sanctis, M.; Dolezal, J.; Jimenez-Alfaro, B.; Herault, B.; Homeier, J.; Kattge, J.; Meir, P.; Mencuccini, M.; Noroozi, J.; Nowak, A.; Penuelas, J.; Schmidt, M.; Skvorc, Z.; Sultana, F.; Magana Ugarte, R. & Bruelheide, H. (2023): Rooting depth and xylem vulnerability are independent woody plant traits jointly selected by aridity, seasonality, and water table depth. New Phytologist XX(XX), X-Y.
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DOI: 10.1111/nph.19276
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Abstract:
Abstract:
Evolutionary radiations of woody taxa within arid environments were made possible by multiple trait innovations including deep roots and embolism-resistant xylem, but little is known about how these traits have coevolved across the phylogeny of woody plants or how they jointly influence the distribution of species.
We synthesized global trait and vegetation plot datasets to examine how rooting depth and xylem vulnerability across 188 woody plant species interact with aridity, precipitation seasonality, and water table depth to influence species occurrence probabilities across all biomes.
Xylem resistance to embolism and rooting depth are independent woody plant traits that do not exhibit an interspecific trade-off. Resistant xylem and deep roots increase occurrence probabilities in arid, seasonal climates over deep water tables. Resistant xylem and shallow roots increase occurrence probabilities in arid, nonseasonal climates over deep water tables. Vulnerable xylem and deep roots increase occurrence probabilities in arid, nonseasonal climates over shallow water tables. Lastly, vulnerable xylem and shallow roots increase occurrence probabilities in humid climates.
Each combination of trait values optimizes occurrence probabilities in unique environmental conditions. Responses of deeply rooted vegetation may be buffered if evaporative demand changes faster than water table depth under climate change.
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Keywords: |
cavitation |
drougt avoider |
drought resistant |
water availability |
Alvarez Figueroa, P.A.; Velescu, A.; Pierick, K.; Homeier, J. & Wilcke, W. (2023): Carbon stable isotope ratios of dissolved organic matter as a tool to identify its sources and transformations in a tropical montane forest in Ecuador. Environmental Science and Technology 57, 14983−14993.
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DOI: 10.1021/acs.est.3c01623
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Abstract:
Abstract:
Dissolved organic matter (DOM) contributes to forest C cycling. We assessed temporal variability, sources, and transformations of DOM during four years in a tropical montane forest with the help of stable C isotope ratios (δ13C values). We measured δ13C values of DOM in rainfall (RF), throughfall (TF), stemflow (SF), litter leachate (LL), soil solutions at the 0.15 and 0.30 m depths (SS15, SS30), and streamflow (ST)with TOC-IRMS. The δ13C values of DOM did not vary seasonally. We detected an event with a high δ13C value likely attributable to black carbon from local pasture fires. The mean δ13C values of DOM outside the event decreased in the order, RF (−26.0 ± 1.3‰) > TF (−28.7 ± 0.3‰) > SF (−29.2 ± 0.2‰) > LL (−29.6 ± 0.2‰) because of increasing leaching of C-isotopically light compounds. The higher δ13C values of DOM in SS15 (−27.8 ± 1.0‰), SS30 (−27.6 ± 1.1‰), and ST (−27.9 ± 1.1‰) than in the above-ground solutions suggested that roots and root exudates are major belowground DOM sources. Although in DOM the C/N ratios correlated with the δ13C values when all solutions were considered, this was not the case for SS15, SS30, and ST alone. Thus, the δ13C values of DOM provide an additional tool to assess the sources and turnover of DOM.
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Keywords: |
C/N ratio |
13C natural abundance |
Dissolved organic carbon |
Moses, J.; Peters, M.K.; Tiede, Y.; Mottl, O.; Donoso, D.A.; Farwig, N.; Fayle, T.M.; Novotny, V.; Sanders, N.J. & Klimes, P. (2023): Nutrient use by tropical ant communities varies among three extensive elevational gradients: A cross-continental comparison. Global Ecology and Biogeography n/a(n/a), -.
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DOI: 10.1111/geb.13757
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Abstract:
Abstract:
Abstract Aim Many studies demonstrate that climate limits invertebrates along tropical elevational gradients, but we have only a rudimentary understanding of the role of nutrient limitation and climatic seasonality. Here we examined the relationships between ant community structure, nutrient use and season along three undisturbed elevational gradients, each from a different continent. Location Ecuador (South America), Papua New Guinea (PNG: Oceania), Tanzania (Africa). Time period 2011–2014. Major taxa studied Ants. Methods Along each of the three gradients, we placed six distinct nutrient types (amino acid, sucrose, sucrose + amino acid, lipid, NaCl, H2O). In total, we distributed 2370 baits at 38 sites from 203 m to 3972 m. We used generalized linear models to test for the effects of elevation and season on ant species richness and activity and relative nutrient use. We also tested if changes in ant trophic guilds corresponded to changes in the use of particular nutrients. Results Both species richness and activity decreased with elevation along each gradient. However, there were significant interaction effects among elevation, region and season, as ant activity in the dry season was higher in Ecuador and Tanzania but lower in PNG. Relative nutrient use varied among regions: ant preference for some nutrients changed with increasing elevation in Ecuador (decrease in lipid use) and Tanzania (decrease in amino acid and H2O use), while season affected nutrient use in PNG. There were common trends in trophic guilds along the three elevational gradients (e.g. proportional increase of predators), but these did not explain most of the nutrient use patterns. Main conclusion While the structure of ant communities changed similarly with elevation, both the seasonal and elevational effects on nutrient use by ants differed between continents. We argue that regional differences in climate and nutrient availability rather than ant functional composition shape nutrient use by ants.
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Keywords: |
nutrient use |
Formicidae |
elevational gradients |
feeding preference |
foraging |
functional group |
intercontinental differences |
invertebrates |
seasonal shifts |
tropical forests |
Barczyk, M.; Acosta Rojas, D.C.; Espinosa, C.I.; Schleuning, M. & Neuschulz, E.L. (2023): Biotic pressures and environmental heterogeneity shape beta- diversity of seedling communities in tropical montane forests. Ecography e06538, 1-11.
Acosta Rojas, D.C.; Barczyk, M.; Espinosa, C.I.; Farwig, N.; Homeier, J.; Tiede, Y.; Velescu, A.; Tinoco, B.A.; Wilcke, W.; Neuschulz, E.L. & Schleuning, M. (2023): Abiotic factors similarly shape the distribution of fruit, seed and leaf traits in tropical fleshy-fruited tree communities. Acta Oecologica 121, 103953.
Acosta Rojas, D.C.; Barczyk, M.; Espinosa, C.I.; Tinoco, B.A.; Neuschulz, E.L. & Schleuning, M. (2023): Climate and microhabitat shape the prevalence of endozoochory in the seed rain of tropical montane forests. Biotropica 55, 408-417.
Knoke, T.; Hanley, N.; Roman-Cuesta, R.M.; Groom, B.; Venmans, F. & Paul, C. (2023): Trends in tropical forest loss and the social value of emission reductions. Nature Sustainability online, 1-15.
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DOI: 10.1038/s41893-023-01175-9
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Abstract:
Abstract:
Reducing global forest losses is essential to mitigate climate change and
its associated social costs. Multiple market and non-market factors can
enhance or reduce forest loss. Here, to understand the role of non-market
factors (for example, policies, climate anomalies or conflicts), we can
compare observed trends to a reference (expected) scenario that excludes
non-market factors. We define an expected scenario by simulating
land-use decisions solely driven by market prices, productivities and
presumably plausible decision-making. The land-use allocation model
considers economic profits and uncertainties as incentives for forest
conversion. We compare reference forest losses in Brazil, the Democratic
Republic of Congo and Indonesia (2000–2019) with observed forest
losses and assign differences from non-market factors. Our results
suggest that non-market factors temporarily lead to lower-than-expected
forest losses summing to 11.1 million hectares, but also to phases with
higher-than-expected forest losses of 11.3 million hectares. Phases with
lower-than-expected forest losses occurred earlier than those with
higher-than-expected forest losses. The damages avoided by delaying
emissions that would otherwise have occurred represent a social value
of US$61.6 billion (as of the year 2000). This result shows the economic
importance of forest conservation efforts in the tropics, even if reduced
forest loss might be temporary and reverse over time.
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Keywords: |
land use change |
land use modeling |
social costs of carbon |
Cornejo, X.; Homeier, J. & Ulloa, C. (2023): Heisteria austroecuadorica (Erythropalaceae): A new species from southeastern Ecuador. Phytotaxa 599(3), 201-206.
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DOI: 10.11646/phytotaxa.599.3.7
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Abstract:
Abstract:
Heisteria austroecuadorica, a new species of Erythropalaceae from the conserved evergreen montane forest at the San Francisco reserve, in southeastern Ecuador, is here described and illustrated. It is characterized by the flowers with 10 stamens, and relatively large fruits, with the apex conspicuously depressed, and the calyx not covering the base of the fruits.
Heisteria austroecuadorica is assessed provisionally as Endangered.
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Keywords: |
San Francisco |
montane forest |
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 |
Knoke, T.; Gosling, E. & Reith, E. (2022): Understanding and modelling the ambiguous impact of off-farm income on tropical deforestation. Journal of Land Use Science 17, 1-20.
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DOI: 10.1080/1747423X.2022.2146220
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Abstract:
Abstract:
Few land-allocation models consider the impact of off-farm income on
tropical deforestation. We provide a concept to integrate off-farm income
in a mechanistic multiple-objective land-allocation model, while distinguishing
between farms with and without re-allocation of on-farm labor
to obtain off-farm income. On farms with re-allocation of labor we found
that off-farm income reduced farmers’ financial dependency on deforestation-
related agricultural income leading to less tropical deforestation.
The influence of off-farm income covered two aspects: availability of
additional income and re-allocation of on-farm labor to off-farm activities.
The labor effect tended to reduce deforestation slightly more than the
income effect. On farms without re-allocation of on-farm labor we showed
how farmers can use off-farm income to purchase additional labor to
accelerate deforestation. Our study highlights the importance of considering
off-farm income in land-use models to better understand, model
and possibly curb tropical deforestation.
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Keywords: |
land use change |
Husmann, K.; von Groß, V.; Bödeker, K.; Fuchs, J.; Paul, C. & Knoke, T. (2022): optimLanduse: A package for multiobjective land-cover composition optimization under uncertainty. Methods in Ecology and Evolution Online, 1-10.
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DOI: 10.1111/2041-210X.14000
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Abstract:
Abstract:
1. How to simultaneously combat biodiversity loss and maintain ecosystem functioning
while improving human welfare remains an open question. Optimization
approaches have proven helpful in revealing the trade-offs
between multiple
functions and goals provided by land-cover
configurations. The R package optim-
Landuse provides tools for easy and systematic applications of the robust multiobjective
land-cover
composition optimization approach of Knoke et al. (2016).
2. The package includes tools to determine the land-cover
composition that best
balances the multiple functions a landscape can provide, and tools for understanding
and visualizing the reasoning behind these compromises. A tutorial
based on a published dataset guides users through the application and highlights
possible use-cases.
3. Illustrating the consequences of alternative ecosystem functions on the theoretically
optimal landscape composition provides easily interpretable information
for landscape modelling and decision-making.
4. The package opens the approach of Knoke et al. (2016) to the community of
landscape modellers and planners and provides opportunities for straightforward
systematic or batch applications.
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Keywords: |
models of land-use/land-cover change |
multicriteria assessment |
robust optimization |
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.
Pierick, K.; Leuschner, C.; Link, R.; Baez, S.; Velescu, A.; Wilcke, W. & Homeier, J. (2024): Above-and belowground strategies of tropical montane tree species are coordinated and driven by small-scale nitrogen availability. Functional Ecology 38, 1364-1377.
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DOI: 10.1111/1365-2435.14554
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Abstract:
Abstract:
1. The question whether the strategies of above-and belowground plant organs
are coordinated as predicted by the plant economics spectrum theory is still
under debate. We aim to determine the leading dimensions of tree trait variation
for above-and belowground functional traits, and test whether they represent
spectra of adaptation along a soil fertility gradient in tropical Andean
forests.
2. We measured leaf, stem and fine root functional traits, and individual-level
soil nutrient availability for 433 trees from 52 species at three elevations between
1000 and 3000 m a.s.l.
3. We found close coordination between above– and belowground functional traits
related to the trade-off between resource acquisition and conservation, whereas
root diameter and specific root length formed an independent axis of covarying
traits. The position of a tree species along the acquisition–conservation axis of
the trait space was closely associated with local soil nitrogen, but not phosphorus,
availability.
4. Our results imply that above-and belowground plant functional traits determine
at which edaphic microhabitats coexisting tree species can grow, which is potentially
crucial for understanding community assembly in species-rich
tropical montane forests.
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Keywords: |
Ecuador |
tropical montane forest |
fine roots |
intraspecific variability |
functional traits |
Pierick, K.; Link, R.; Leuschner, C. & Homeier, J. (2022): Elevational trends of tree fine root traits in species-rich tropical Andean forests. Oikos 2023, e08975.
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DOI: 10.1111/oik.08975
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Abstract:
Abstract:
With increasing elevation, trees in tropical montane forests have to invest larger frac-tions of their resources into their fine roots in order to compensate for increasingly unfavorable soil conditions. It is unclear how elevation and related edaphic changes influence the variability in tree fine root traits and belowground functional diversity. We measured six fine root traits related to resource acquisition on absorptive fine roots of 288 trees from 145 species along an elevational gradient from 1000 m to 3000 m a.s.l. in tropical montane forests of the Ecuadorian Andes. We analyzed trait relation-ships with elevation and soil nutrient availability, and tested whether root functional diversity varied along these gradients. Fine roots at higher elevations and at more nutrient-poor sites were thicker, had higher tissue densities, and lower specific root length and nutrient concentrations than at lower elevations. These trends were diluted by the coexistence of tree species with a broad range of different root traits within communities particularly towards lower elevations, where root functional diversity was significantly higher. We conclude that nutrient limitation and potentially further adverse conditions at higher elevations are strong environmental filters that lead to trait convergence towards a conservative resource use strategy, whereas different trait syndromes are equally successful at lower elevations.
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Keywords: |
Ecuador |
tropical montane forest |
fine roots |
elevational gradient |
functional traits |