Publications
Found 194 publication(s)
- of type
Murkute, C.P.; Sayeed, M.; Pucha-Cofrep, F.; Carrillo-Rojas, G.; Homeier, J.; Limberger, O.; Fries, A.; Bendix, J. & Trachte, K. (2024): Turbulent Energy and Carbon Fluxes in an Andean Montane Forest—Energy Balance and Heat Storage. Forests 15(10), 1828.
Schoen, J.; Keuth, R.; Homeier, J.; Limberger, O.; Bendix, J.; Farwig, N. & Brandl, R. (2024): Do leaf traits shape herbivory in tropical montane rainforests? A multispecies approach. Ecosphere 15(10), 1-15.
-
download
-
link
-
view metadata
-
DOI: 10.1002/ecs2.70018
-
Abstract:
Abstract:
The co-evolutionary arms race between herbivores and plants forces plants to evolve protection strategies that reduce the palatability of the plant modules attacked by the herbivores. These characteristics of traits have consequences for both the survival of plant individuals and the composition of plant communities. Thus, correlating traits of for instance leaves with herbivory is an important step toward understanding the dynamics of plant populations and communities. Traits can either be measured using conventional lab methods or recently developed spectral sensing techniques. We examined whether leaf traits of trees are related to herbivory in a multispecies approach. Furthermore, we explored whether leaf traits characterized by spectral sensing provide similar relations to herbivory as lab-based leaf traits. We established nine 1-ha square plots evenly distributed over three different forest types in Ecuadorian tropical montane rainforests where we estimated herbivory as the leaf area loss (in square centimeters) of 20 (±5) leaves sampled from the canopies of 380 tree individuals belonging to 51 tree species (7 ± 1 individuals/species) using lab- and spectral-sensing-based methods. For each methodological approach, we ran 100 linear mixed-effects models with all respective leaf traits as predictor and herbivory as response variables for data subsets containing one randomly selected tree individual of each species to estimate the range of the regression coefficients for each trait. Automated stepwise backward selections determined the frequency of each trait having an important influence on herbivory. We found no clear relations between leaf traits and herbivory for neither lab- nor spectral-sensing-based traits. A nested variance component analysis demonstrated that the observed variability was mainly due to the variation in trait concentrations between tree individuals of a species. Our results suggest that snapshot data lead to a mismatch between herbivory and the concentrations of traits during the peak of herbivory. Another explanation could be that environmental conditions or processes along the food web are more important in structuring herbivory than leaf traits.
-
Keywords: |
Ecuador |
herbivory |
leaf area loss |
plant defense |
plant nutrients |
secondary metabolites |
spectral sensing |
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.
-
download
-
link
-
view metadata
-
DOI: 10.1029/2024JG008043
-
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.
-
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.
-
download
-
link
-
view metadata
-
DOI: 10.3390/plants13182555
-
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.
-
Keywords: |
biomass |
beta diversity |
species turnover |
Alpha diversity |
competition |
biotic interactions |
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.
-
download
-
link
-
view metadata
-
DOI: 10.1038/s41597-022-01626-6
-
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.
-
Keywords: |
Andes |
plant functional traits |
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.
-
download
-
link
-
view metadata
-
DOI: 10.1002/pei3.10139
-
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.
-
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.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1371/journal.pone.0288276
-
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.
-
Keywords: |
insect herbivores |
abundance |
morphological traits |
leaf functional traits |
Jarman-Bell principle |
leaf chewers |
rostrum chewers |
palatability |
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.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1111/nph.19276
-
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.
-
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.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1021/acs.est.3c01623
-
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.
-
Keywords: |
C/N ratio |
13C natural abundance |
Dissolved organic carbon |
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.
Cornejo, X.; Homeier, J. & Ulloa, C. (2023): Heisteria austroecuadorica (Erythropalaceae): A new species from southeastern Ecuador. Phytotaxa 599(3), 201-206.
-
download
-
link
-
view metadata
-
DOI: 10.11646/phytotaxa.599.3.7
-
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.
-
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), -.
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.
-
download
-
link
-
view metadata
-
DOI: 10.1111/1365-2435.14554
-
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.
-
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.
-
download
-
link
-
view metadata
-
DOI: 10.1111/oik.08975
-
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.
-
Keywords: |
Ecuador |
tropical montane forest |
fine roots |
elevational gradient |
functional traits |
Báez, S.; Fadrique, B.; Feeley, K. & Homeier, J. (2022): Changes in tree functional composition across topographic gradients and through time in a tropical montane forest. PLOS ONE 17(4), e0263508.
-
download
-
link
-
view metadata
-
DOI: 10.1371/journal. pone.0263508
-
Abstract:
Abstract:
Understanding variation in tree functional traits along topographic gradients and through time provides insights into the processes that will shape community composition and determine ecosystem functioning. In montane environments, complex topography is known to affect forest structure and composition, yet its role in determining trait composition, indices on community climatic tolerances, and responses to changing environmental conditions has not been fully explored. This study investigates how functional trait composition (characterized as community-weighted moments) and community climatic indices vary for the tree community as a whole and for its separate demographic components (i.e., dying, surviving, recruiting trees) over eight years in a topographically complex tropical Andean forest in southern Ecuador. We identified a strong influence of topography on functional composition and on species’ climatic optima, such that communities at lower topographic positions were dominated by acquisitive species adapted to both warmer and wetter conditions compared to communities at upper topographic positions which were dominated by conservative cold adapted species, possibly due to differences in soil conditions and hydrology. Forest functional and climatic composition remained stable through time; and we found limited evidence for trait-based responses to environmental change among demographic groups. Our findings confirm that fine-scale environmental conditions are a critical factor structuring plant communities in tropical forests, and suggest that slow environmental warming and community-based processes may promote short-term community functional stability. This study highlights the need to explore how diverse aspects of community trait composition vary in tropical montane forests, and to further investigate thresholds of forest response to environmental change.
-
Keywords: |
Ecuador |
forest dynamics |
environmental change |
plant functional traits |
tropical montane forests (TMF) |
topography |
Weigand, A.; Homeier, J.; Lehnert, M. & Kessler, M. (2022): Influence of increasing nutrient availability on fern and lycophyte diversity. American Fern Journal 112(1), 17-35.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1640/0002-8444-112.1.17
-
Abstract:
Abstract:
Increased nutrient supply can have drastic effects on natural ecosystems, especially in
naturally nutrient-poor ones such as most tropical rainforests. Many studies have focused on the reaction of trees to fertilization, but little is known about herbaceous plants. Ferns are a particularly common group in tropical forests, spanning all vegetation types and zones. Here, we assess how seven years of moderate addition of nitrogen (N), phosphorus (P), and N+P along an elevational gradient (1000–3000 m) have impacted richness and composition of fern and lycophyte assemblages in tropical montane rain forests growing on naturally nutrient deficient soils in the Ecuadorian Andes. We found that fertilization does not affect overall species richness, but that there were strong differences in species abundances (~60% of species), both negative and positive, that were apparently related to the systematic affiliations and ecological properties of the affected species. These diverse responses of ferns to fertilization provide insight into the sensitivity and complexity of the relationships of nutrient availability and community composition in tropical forests.
-
Keywords: |
NUMEX |
diversity |
Andes |
tropical montane forest |
elevational gradient |
experimental nutrient addition |
fern |
Ostertag, R.; Restrepo, C.; Dalling, J.W.; Martin, P.H.; Abiem, I.; Aiba, S.; Alvarez-Dávila, E.; Aragón, R.; Ataroff, M.; Chapman, H.; Cueva, A.; Fadrique, B.; Fernández, R.D.; González, G.; Gotsch, S.G.; Häger, A.; Homeier, J.; Iñiguez-Armijos, C.; Llambi, L.D.; Moore, G.W.; Næsborg, R.R.; Poma López, L.N.; Vieira Pompeu, P.; Powell, J.R.; Ramírez Correa, J.A.; Scharnagl, K.; Tobón, C. & Williams, C.B. (2021): Litter decomposition rates across tropical montane and lowland forests are controlled foremost by climate. Biotropica 54(2), 309-326.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1111/btp.13044
-
Abstract:
Abstract:
The “hierarchy of factors” hypothesis states that decomposition rates are controlled primarily by climatic, followed by biological and soil variables. Tropical montane forests (TMF) are globally important ecosystems, yet there have been limited efforts to provide a biome-scale characterization of litter decomposition. We designed a common litter decomposition experiment replicated in 23 tropical montane sites across the Americas, Asia, and Africa and combined these results with a previous study of 23 sites in tropical lowland forests (TLF). Specifically, we investigated (1) spatial heterogeneity
in decomposition, (2) the relative importance of biological factors that affect leaf and wood decomposition in TMF, and (3) the role of climate in determining leaf litter decomposition rates within and across the TMF and TLF biomes. Litterbags of two mesh sizes containing Laurus nobilis leaves or birchwood popsicle sticks were spatially dispersed and incubated in TMF sites, for 3 and 7 months on the soil surface and at 10–15 cm depth. The within-site
replication demonstrated spatial variability in mass loss. Within TMF, litter type was the predominant biological factor influencing decomposition (leaves > wood), with mesh and burial effects playing a minor role.
When comparing across TMF and TLF, climate was the predominant control over decomposition,but the Yasso07 global model (based on mean annual temperature and precipitation) only modestly predicted decomposition rate. Differences in controlling factors between biomes suggest that TMF, with their high rates of carbon storage, must be explicitly considered when developing theory and models to elucidate carbon cycling rates in the tropics.
-
Keywords: |
climate |
decomposition |
tropical montane forests (TMF) |
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.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1038/s41598-021-03488-1
-
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.
-
Keywords: |
Biodiversity |
geodiversity |
Acosta Rojas, D.C.; Barczyk, M.; Espinosa, C.I.; Gusman, J.; Peña, J.; Neuschulz, E.; Schleuning, M. & Homeier, J. 2021: Field guide of animal-dispersed plants: fruits and seeds in and around Podocarpus National Park.: 1 16 (INABIO, Quito).
-
download
-
link
-
view metadata
-
DOI: 10.5678/vnkb-t219
-
Abstract:
Abstract:
Plant communities in tropical mountains host a high diversity of species’ morphological traits. Many tropical plant species exhibit a wide range of colored fleshy fruits mainly dispersed by animals. Fruits display a variety of shapes including, for instance, capsules with arillate seeds, drupes with fibrous pulp, and juicy berries. These fruits can enclose just one or many tiny seeds which are dispersed by animals. In the tropical mountains of the southeast of Ecuador, seed size can vary from less than 1 mm (e.g., Miconia sp.) to large seeds with a size of almost 10 cm.
Despite the high diversity of fleshy-fruited species and the relevance in plant regeneration, there is very little information that facilitates the identification of even the most common fruits and seeds in tropical mountains. The pronounced endemism in the Andes and the constant description of new plant species increase the necessity to foster local publications including these unique species. This project aims to produce an identification guide as a scientific tool to ease the taxonomic determination of seeds dispersed by animals and to speed up the identification process in the mountain forests of the southeast of Ecuador. This field guide will be a source of consultation for future research units at the San Francisco Scientific Station, and will also contribute to public outreach.
-
Keywords: |
tree seeds |
mutualistic interactions |
fruit functional traits |
fleshy-fruited species |
Velescu, A.; Homeier, J.; Bendix, J.; Valarezo, C. & Wilcke, W. (2021): Response of water-bound fluxes of potassium, calcium, magnesium and sodium to nutrient additions in an Ecuadorian tropical montane forest. Forest Ecology and Management 501(119661), 1-14.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1016/j.foreco.2021.119661
-
Abstract:
Abstract:
In the past two decades, the Amazon-exposed, tropical montane rain forests in south Ecuador experienced increasing deposition of reactive N mainly from Amazonian forest fires, episodic Ca and Mg inputs from Saharan dust, and a low but constant P deposition from unknown sources. To explore the response of this tropical, perhumid ecosystem to nutrient inputs, we established in 2007 a Nutrient Manipulation Experiment (NUMEX). Since 2008, we have applied 50 kg ha−1 year−1 of N as urea, 10 kg ha−1 year−1 of P as NaH2PO4·H2O, 50 kg ha−1 year−1 of N + 10 kg ha−1 year−1 of P and 10 kg ha−1 year−1 of Ca as CaCl2·H2O in a randomized block design at 2000 m a.s.l. in a natural forest of the south Ecuadorian Andes. Previous studies have shown that alkali and alkaline earth metals had beneficial effects on the functioning of N and P co-limited tropical forests occurring on acidic soils. Therefore, we determined the response of all major aqueous ecosystem fluxes of K, Ca, Mg and Na to nutrient amendments, to understand how increasing atmospheric deposition would affect their cycling in the future. Additions of N and P decreased K leaching from the organic layer and in the mineral soil, thus tightening K cycling. This suggests that increasing future N and P availability may result in K limitation in the long term. The leaching of Ca and Mg from the canopy increased in response to amendments of N and P and we observed an enhanced uptake of these nutrients also if Ca was amended alone. Although N was applied as urea, acidity of soil solutions and leaching of K, Ca, Mg and Na did not increase following separate N amendments. In spite of the acid soils and of its low cation-exchange competitivity, Na included in the P fertilizer was only partly leached from the organic layer. We suggest that it was probably required to cover an unmet Na demand of the soil fauna. Our results demonstrate the major role in the functioning of the tropical montane forests played by K, Ca and Mg as potential future growth-limiting elements and increasingly required nutrients in response to rising N and P availability, while they also support the importance of Na as a functional element in these ecosystems.
-
Keywords: |
Ecuador |
NUMEX |
nutrient manipulation |
tropical montane forest |
nutrient additions |
base cations |
Dantas De Paula, M.; Forrest, M.; Langan, L.; Bendix, J.; Homeier, J.; Velescu, A.; Wilcke, W. & Hickler, T. (2021): Nutrient cycling drives plant community trait assembly and ecosystem functioning in a tropical mountain biodiversity hotspot. New Phytologist -(-), -.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1111/nph.17600
-
Abstract:
Abstract:
Summary Community trait assembly in highly diverse tropical rainforests is still poorly understood. Based on more than a decade of field measurements in a biodiversity hotspot of southern Ecuador, we implemented plant trait variation and improved soil organic matter dynamics in a widely used dynamic vegetation model (the Lund-Potsdam-Jena General Ecosystem Simulator, LPJ-GUESS) to explore the main drivers of community assembly along an elevational gradient. In the model used here (LPJ-GUESS-NTD, where NTD stands for nutrient-trait dynamics), each plant individual can possess different trait combinations, and the community trait composition emerges via ecological sorting. Further model developments include plant growth limitation by phosphorous (P) and mycorrhizal nutrient uptake. The new model version reproduced the main observed community trait shift and related vegetation processes along the elevational gradient, but only if nutrient limitations to plant growth were activated. In turn, when traits were fixed, low productivity communities emerged due to reduced nutrient-use efficiency. Mycorrhizal nutrient uptake, when deactivated, reduced net primary production (NPP) by 61–72% along the gradient. Our results strongly suggest that the elevational temperature gradient drives community assembly and ecosystem functioning indirectly through its effect on soil nutrient dynamics and vegetation traits. This illustrates the importance of considering these processes to yield realistic model predictions.
-
Keywords: |
mycorrhiza |
dynamic vegetation model |
nutrient cycling |
plant community assembly |
plant functional traits |
tropical montane forests (TMF) |
Limberger, O.; Homeier, J.; Farwig, N.; Pucha-Cofrep, F.; Fries, A.; Leuschner, C.; Trachte, K. & Bendix, J. (2021): Classification of Tree Functional Types in a Megadiverse Tropical Mountain Forest from Leaf Optical Metrics and Functional Traits for Two Related Ecosystem Functions. Forests 12(5), 649.
Homeier, J.; Seeler, T.; Pierick, K. & Leuschner, C. (2021): Leaf trait variation in species-rich tropical Andean forests. Scientific Reports 11, 9993.
-
download
-
link
-
view metadata
-
DOI: 10.1038/s41598-021-89190-8
-
Abstract:
Abstract:
Screening species-rich communities for the variation in functional raits along environmental gradients may help understanding the abiotic drivers of plant performance in a mechanistic way. We investigated tree leaf trait variation along an elevation gradient (1000–3000 m) in highly diverse neotropical montane forests to test the hypothesis that elevational trait change reflects a trend toward more conservative resource use strategies at higher elevations, with interspecific trait variation decreasing and trait integration increasing due to environmental filtering. Analysis of trait variance partitioning across the 52 tree species revealed for most traits a dominant influence of phylogeny, except for SLA, leaf thickness and foliar Ca, where elevation was most influential. The community-level means of SLA, foliar N and Ca, and foliar N/P ratio decreased with elevation, while leaf thickness and toughness increased. The contribution of intraspecific variation was substantial at the community level in most traits, yet smaller than the interspecific component. Both within-species and between-species trait variation did not change systematically with elevation. High phylogenetic diversity, together with small-scale edaphic heterogeneity, cause large interspecific leaf trait variation in these hyper-diverse Andean forests. Trait network analysis revealed increasing leaf trait integration with elevation, suggesting stronger environmental filtering at colder and nutrient-poorer sites.
-
Keywords: |
leaf functional traits |
Homeier, J. & Leuschner, C. (2021): Factors controlling the productivity of tropical Andean forests: climate and soil are more important than tree diversity. Biogeosciences 18(4), 1524-1541.
-
download
-
link
-
view metadata
-
DOI: 10.5194/bg-18-1525-2021
-
Abstract:
Abstract:
Theory predicts positive effects of species richness on the productivity of plant communities through complementary resource use and facilitative interactions between species. Results from manipulative experiments with tropical tree species indicate a positive diversity–productivity relationship (DPR), but the existing evidence from natural forests
is scarce and contradictory. We studied forest aboveground productivity in more than 80 humid tropical montane oldgrowth forests in two highly diverse Andean regions with large geological and topographic heterogeneity and related productivity to tree diversity and climatic, edaphic and stand
structural factors with a likely influence on productivity. Main determinants of wood production in the perhumid study regions were elevation (as a proxy for temperature), soil nutrient (N, P and base cation) availability and forest structural parameters (wood specific gravity, aboveground biomass). Tree diversity had only a small positive influence on productivity, even though tree species numbers varied largely (6–27 species per 0.04 ha). We conclude that the productivity of highly diverse Neotropical montane forests is primarily controlled by thermal and edaphic factors and stand structural properties, while tree diversity is of minor importance.
-
Keywords: |
soil nutrients |
wood production |
tropical montane forest |
elevational gradient |
Aboveground forest productivity |
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.
-
download
-
link
-
view metadata
-
DOI: 10.1007/s00442-021-04852-8
-
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.
-
Keywords: |
Biodiversity-Land-Surface-Model |
Pierick, K.; Leuschner, C. & Homeier, J. (2021): Topography as a factor driving small‐scale variation in tree fine root traits and root functional diversity in a species‐rich tropical montane forest. New Phytologist 230(1), 129-138.
-
link
-
view metadata
-
DOI: 10.1111/nph.17136
-
Abstract:
Abstract:
(1) We investigated the variation in tree fine root traits and their functional diversity along a local topographic gradient in a Neotropical montane forest to test if fine root trait variation along the gradient is consistent with the predictions of the root economics spectrum on a shift from acquisitive to conservative traits with decreasing resource supply.
(2) We measured five fine root functional traits in 179 randomly selected tree individuals of 100 species and analyzed the variation of single traits (using Bayesian phylogenetic multi‐level models) and of functional trait diversity with small scale topography.
(3) Fine roots exhibited more conservative traits (thicker diameters, lower specific root length and nitrogen concentration) at upper slope compared to lower slope positions, but the largest proportion of variation (40‐80%) was explained by species identity and phylogeny. Fine root functional diversity decreased towards the upper slopes.
(4) Our results suggest that local topography and the related soil fertility and moisture gradients cause considerable small‐scale variation in fine root traits and functional diversity along tropical mountain slopes, with conservative root traits and greater trait convergence being associated with less favorable soil conditions due to environmental filtering. We provide evidence of a high degree of phylogenetic conservation in fine root traits.
-
Keywords: |
Ecuador |
tropical montane forest |
root functional traits |
root economics spectrum |
phylogenetic regression |
functional dispersion |
Bayesian multi-level models |
Graefe, S.; Rodrigo, R.; Cueva, E.; Butz, P.; Werner, F.A. & Homeier, J. (2020): Impact of disturbance on forest structure and tree species composition in a tropical dry forest of South Ecuador. Ecotropica 22, 202002.
-
download
-
link
-
view metadata
-
DOI: 10.30427/ecotrop202002
-
Abstract:
Abstract:
Tropical dry forests (TDFs) are often degraded and fragmented through human impact, which is also the case in Southern Ecuador, where land-use pressure is high. In this context we studied tree species composition and forest structure in a protected and adjacent disturbed TDF at altitudes between 560-1080 m asl. Fabaceae and Malvaceae were identified as the most important tree families in both forest types. The disturbed forest displayed lower tree species richness than the protected forest, and the gap in species richness between the two forest types increased with increasing altitude. Ten species of the protected forest were not recorded in the disturbed forest, two of them endemic. The disturbed site was further characterized by a lower number of stems but with larger diameters, in comparison with the protected forest. The majority of the most abundant tree species in the disturbed forest had rather low wood densities, but also the combination of high wood density with browsing tolerance and high resprouting capacity was encountered, and seems to be advantageous for getting established in such sites. Although certain tree species were well represented in the disturbed forest, some endemic species with relatively low abundances (e.g. Simira ecuadorensis, Prockia crucis) should receive more conservation attention.
-
Keywords: |
species richness |
altitude |
importance value index |
Tumbesian dry forest |
wood density |
Wallis, C.; Homeier, J.; Pena Tamayo, J.E.; Brandl, R.; Farwig, N. & Bendix, J. (2019): Modeling tropical montane forest biomass, productivity and canopy traits with multispectral remote sensing data. Remote Sensing of Environment 225, 77 - 92.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1016/j.rse.2019.02.021
-
Abstract:
Abstract:
Tropical montane forests, particularly Andean rainforest, are important ecosystems for regional carbon and water cycles as well as for biological diversity and speciation. Owing to their remoteness, however, ecological key-processes are less understood as in the tropical lowlands. Remote sensing allows modeling of variables related to spatial patterns of carbon stocks and fluxes (e.g., biomass) and ecosystem functioning (e.g., functional leaf traits). However, at a landscape scale most studies conducted so far are based on airborne remote sensing data which is often available only locally and for one time-point. In contrast, multispectral satellites at moderate spectral and spatial resolutions are able to provide spatially continuous and repeated observations. Here, we investigated the effectiveness of Landsat-8 imagery in modeling tropical montane forest biomass, its productivity and selected canopy traits. Topographical, spectral and textural metrics were derived as predictors. To train and validate the models, in-situ data was sampled in 54 permanent plots in forests of southern Ecuador distributed within three study sites at 1000 m, 2000 m and 3000 m a.s.l. We used partial least squares regressions to model and map all response variables. Along the whole elevation gradient biomass and productivity models explained 31%, 43%, 69% and 63% of variance in aboveground biomass, annual wood production, fine litter production and aboveground net primary production, respectively. Regression models of canopy traits measured as community weighted means explained 62%, 78%, 65% and 65% of variance in leaf toughness, specific leaf area, foliar N concentration, and foliar P concentration, respectively. Models at single study sites hardly explained variation in aboveground biomass and the annual wood production indicating that these measures are mainly determined by the change of forest types along with elevation. In contrast, the models of fine litter production and canopy traits explained between 8%–85% in variation depending on the study site. We found spectral metrics, in particular a vegetation index using the red and the green band to provide complementary information to topographical metrics. The model performances for estimating leaf toughness, biochemical canopy traits and related fine litter production all improved when adding spectral information. Our findings therefore revealed that differences in fine litter production and canopy traits in our study area are driven by local changes in vegetation edaphically induced by topography. We conclude that Landsat-derived metrics are useful in modeling fine litter production and biochemical canopy traits, in a topographically and ecologically complex tropical montane forest.
-
Keywords: |
Ecuador |
Aboveground forest productivity |
Ecosystem process |
Fine litter production |
Foliar N |
Foliar P |
Grey level co-occurrence texture |
Landsat-8 |
Leaf toughness |
Specific leaf area |
Annual wood production |
Duenas, J.F.; Camenzind, T.; Roy, J.; Hempel, S.; Homeier, J.; Suarez, J.P. & Rillig, M.C. (2020): Moderate phosphorus additions consistently affect community composition of arbuscular mycorrhizal fungi in tropical montane forests in southern Ecuador. New Phytologist 227, 1505-1518.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1111/NPH.16641
-
Abstract:
Abstract:
Anthropogenic atmospheric deposition can increase nutrient supply in the most remote ecosystems, potentially affecting soil biodiversity. Arbuscular mycorrhizal fungal (AMF) communities rapidly respond to simulated soil eutrophication in tropical forests. Yet the
limited spatio-temporal extent of such manipulations, together with the often unrealistically high fertilization rates employed, impedes generalization of such responses.
We sequenced mixed root AMF communities within a seven year-long fully factorial nitrogen (N) and phosphorus (P) addition experiment, replicated at three tropical montane forests in southern Ecuador with differing environmental characteristics. We hypothesized
(i) strong shifts in community composition and species richness after long-term fertilization, (ii) site- and (iii) clade-specific responses to N versus P additions depending on local soil fertility and clade life history traits respectively.
Fertilization consistently shifted AMF community composition across sites, but only reduced richness of Glomeraceae. Compositional changes were mainly driven by increases in P supply while richness reductions were observed only after combined N and P additions.
We conclude that moderate increases of N and P exert a mild but consistent effect on tropical AMF communities. To predict the consequences of these shifts, current results need to be supplemented with experiments that characterize local species-specific AMF
functionality.
-
Keywords: |
NUMEX |
San Francisco |
Bombuscaro |
Cajanuma |
Nutrient deposition |
Arbuscular mycorrhizal fungi |