Environmental changes in biodiversity hotspot ecosystems of
South Ecuador: RESPonse and feedback effECTs (FOR2730)

Abstract:

Geographic Information Systems and Remote Sensing are important contributors to Sustainable Forestry Management Plans. Remote sensing techniques for image interpretation provides the means to extract valuable information that could be expensive and time-consuming to obtain through field observations (Franklin et al. 2001). Spatial Products derived from the interpretation of airborne and satellite borne images feed Geographic Information Systems to develop strategies and methodologies for resource management, harvest planning, fire management, map production, and model predictions. (Yusmah et al. 2015) This study has three important objectives: to test the feasibility of template matching for the identification of single pine tree crowns, to conduct a delineation of pine plantations using relational features and to evaluate how single tree crown size affects the accuracy of the proposed method. Templates of single trees were produced in the software eCognition Developer. The sampling process comprised the random selection of 3000 single pine trees in 7 different test sites (test sites were grouped in 3 categories according to the single tree sizes). A first rule set to detect single tree crowns was developed in eCognition Developer, using three different template groups (4, 8 and 16 templates). Through an analysis of variance, the number of single tree crowns detected was compared for the different template groups. Using a second rule set in eCognition, the template matching algorithm combined with relational, spectral and contextual information were applied to delineate pine plantation areas. An accuracy assessment was performed in the test sites for all thematic classes identified. Finally, an Analysis of Variance evaluated the influence of single tree crown size on the overall accuracy. Potential applications and improvements to the proposed methodology for single tree crown detection and plantation delineation are proposed at the end of the document.

Abstract:

In this study we performed anatomic, physical-mechanical and chemical measurements on a set of small test samples of 27 wood species from the tropical mountain forest in Ecuador. We determined color and vessel arrangement, wood density (bulk and dry density) and wood moisture content, vessel density and vessel diameter, extractive contents, Young’s modulus ED (parallel and transverse to the grain) and failure strain ?D|| (parallel to the grain). For dry density we found a wide range of 0,25 - 0,95 g/cm-3. Extractive contents were strikingly low (1,44 ± 0,79 Gew.%). The best correlation (R2 = 0,82) exists for ?D|| and dry density. Moreover, it is interesting that the geometric mean of ED values parallel and transverse to the grain strongly correlates with dry density (R2 = 0,74), and especially better than ED values in single directions. The results of this study provide indications for further investigations in this test area. In an outlook we give recommendations regarding the required sample size for future studies allowing statistical analyses of the important wood properties.

Abstract:

Ecosystem services, provided from tropical forests, are indispensable for human beings. Coherencies in the system, their networks, drivers and various underlying pathways are not completely understood yet. Elucidation on directions of key nutrients and changes in organisms delivers the opportunity to get an overview about these relations. Leaf functional traits are one important component to uncover those cascades and organizations. With their fast respond to environmental conditions, changes can be detected. Since, tropical regions suffer from increasing atmospheric inputs of nitrogen (N) and phosphorus (P), it is a need to investigate these progressions and predict future scenarios. The alarming fact, that these anthropogenic caused input have unknown consequences for the structure and functioning of tropical forests leads to a crucial study topic. Furthermore, questions should be answered if these increased inputs have a comparable influence on different elevations, based on identification the limiting nutrients. To forecast these impacts the Nutrient Manipulation Experiment (NUMEX) has been conducted since 2008. It gained to show, that Neotropical montane forests respond rapidly to moderate nutrient additions of N (50 kg ha-1 yr-1) and P (10 kg ha-1 yr-1). Within the present study, the eight most abundant tree species from the NUMEX sites were analyzed to their leaf functional traits from three elevations (altitude above sea level) in an Ecuadorian montane forest. The premontane forest in Bombuscaro (1,000 m) contains the species Clarisia racemosa and Pouteria torta. Further, in San Francisco (2,000 m), Alchornea lojaensis, Graffenrieda emarginata, Hieronyma fendleri, and Myrcia sp., were selected. In Cajanuma (3,000 m), the upper montane forest contains Hedyosmum purpurascens and Weinmannia loxensis. The fertilization effects were calculated, using a mixed effect model, including study year and treatment as fixed effects and block and individual as random effects. The results show, that foliar N decrease over the years, whereas, Foliar P conversely increases. Further, the relation of nitrogen and phosphorus (N:P) is decreasing during the study years. Upwards trends for ?15N are best replicated for the San Francisco site. With the leaf trait nutrient resorption efficiency (NuR) for N and P a decline over the study years is proceeding. In addition, leaf area (LA) and specific leaf area (SLA) tend to decrease. In conclusive processes over the study years might be the result of microclimatic events. The sites differ in that San Francisco and Cajanuma respond more similar in some leaf functional traits, compared to them from Bombuscaro. It can be deduced that changes in the analyzed leaf traits over the last eight years between the sites and species are not significantly different. Summarizing, results represent the emphasis on the considerable influence of nutrient addition with notably changing foliar nutrient and show that the predicted nutrient deposition will probably change the ecosystem dynamics sustained.

Abstract:

Tropical montane forests of the Andes belong to the hotspots of biodiversity. But these nutrient poor ecosystems are simultaneously threatened by increased element inputs of nitrogen and phosphor in nutrient cycles. NUMEX-Projekt simulates the expected nutrient inputs in the for-ests and quantifies the changes of this ecosystem. In line of this study litter samples were collected by littertraps during a working period from February till May 2016. Leaf litter produc-tion, parameters of leaf morphology (leaf area and specific leaf area) and litter nutrients of nitrogen and phosphor were determined. Additionally, the parameters of herbivory (leaf mass loss and leaf area loss) were calculated by measuring holes area. The variation of these pa-rameters along an altitudinal gradient from 1.000 m.a.s.l. to 3.000 m.a.s.l. was investigated. Besides the variation after nitrogen and/or phosphor addition was explored. Furthermore, the extend of nutrients, lost through herbivory, was identified for the stand level. Terminatory the influence of two soil parameters (C/N ratio and Presin) was discussed. There is a significant influence of altitude (p<0,05) on leaf morphology (leaf area: 1.000 m.a.s.l: 26,4±1,6 cm², 3.000 m.a.s.l: 7,4±1,0 cm², specific leaf area: 1.000 m.a.s.l: 99,7±4,1 cm²·g-1, 3.000 m.a.s.l: 56,1±6,6 cm²·g-1), leaf nutrients of nitrogen (1.000 m.a.s.l: 15,3±0,5 g·kg-1, 3.000 m.a.s.l: 6,6±0,7 g·kg-1) and phosphor (1.000 m.a.s.l: 0,54±0,03 g·kg-1, 3.000 m.a.s.l: 0,25±0,03 g·kg-1) and also on the parameters of herbivory: holes area (1.000 m.a.s.l: 1,8±0,2 cm², 3.000 m.a.s.l: 0,3±0,1 cm²) and leaf area loss (1.000 m.a.s.l: 6,8±0,4 %, 3.000 m.a.s.l: 3,6±0,6 %). Nutrient addition did not lead to distinct results according to the variation of measured param-eters. NP fertilization had a positive effect on leaf area and P fertilization a positive effect on specific leaf area. Leaf nutrients showed various answers. For this parameter, NP fertilization causes significantly raised nitrogen and phosphor concentrations in litter in each site. Leaf litter production in 1.000 m.a.s.l site significantly decreased through NP fertilization. Referring to herbivory only a little number of significant effects were detected. Holes area increased on 2.000 m.a.s.l site by NP addition while leaf area loss in 1.000 m.a.s.l site – as well as leaf area production – decreased. On stand level, there was no variation of leaf area loss. Soil parameters have a higher impact on measured parameters on stand level. Specific leaf area and leaf area loss correlate positively with soil C/N of upper mineral soil. Correlations of these parameters with plant available phosphor Presin is negative. Nutrient losses on stand level decrease with altitude. There was a negative effect of NP addition on nitrogen loss in 1.000 m.a.s.l site and a positive effect of NP addition on phosphor loss in all sites.

Abstract:

This paper focuses on the analysis of precipitation patterns, using a Local Area Weather Radar to collect information about the precipitation distribution in an Andean region of southern Ecuador (cities of Loja, Zamora and Catamayo). 54 representative events were selected to develop daily precipitation maps and to obtain their relevant characteristics, which were related to the topography and the season. The results showed that a strong correlation between the areas covered by precipitation (RA coefficient) and the season exists. In general, humid air masses come from the east (Amazon Basin), but during the main rainy season (December to April), humidity also frequently enters the study region from the west (Pacific Ocean). The rainy season is characterized by convective precipitation, associated with higher evaporation rates during austral summer. The relatively dry season is formed between May and November, but considerable precipitation amounts are registered, too, due to advective moisture transport from the Amazon Basin, a result of the predominant tropical easterlies carrying the humidity up the eastern escarpment of the Andes, generally following the natural course of the drainage systems.

Abstract:

Uno de los aspectos importantes a considerarse en la producción eficiente de plántulas con fines de restauración es la calidad de semillas y su variabilidad. El objetivo de este estudio fue evaluar los parámetros de semillas de acuerdo con las reglas del “International Seed Testing Association” entre diferentes árboles madre o individuos de siete especies nativas (Cedrela montana, Morella pubescens, Inga acreana, Tabebuia chrysantha, Ocotea heterochroma, Oreocallis grandiflora y Myrcianthes rhopaloides) en dos bosques de montaña del sur del Ecuador. Estas especies fueron seleccionadas por la importancia ecológica, socioeconómica, y su gran potencial para la restauración. De un total de 35 árboles madre de todas las especies, se colectaron las semillas en sus respectivos periodos de fructificación, y en el laboratorio fueron analizados los siguientes parámetros: pureza, peso, contenido de humedad y germinación; adicionalmente se determinó el coeficiente de velocidad de germinación. Los resultados mostraron una similitud intraespecífica en cada especie para la mayoría de los parámetros; no obstante, el peso presentó alta variabilidad intraespecífica para todas las especies. El parámetro germinación obtuvo diferencias entre individuos para C. montana, T. chrysantha, O. heterochroma y M. rhopaloides. En cuanto a la velocidad de germinación, individuos de especies como O. grandiflora e I. acreana mostraron un alto coeficiente en contraste a los individuos de O. heterochroma y M. pubescens. La información generada en este estudio podría ser el primer paso en la formulación de pautas para la producción masiva de plántulas de especies nativas con fines de restauración.

Abstract:

Forest recovery on disturbed areas is of special significance in the Ecuadorian Andes, where deforestation is a serious problem. Natural diachronic succession was evaluated on three large plots or sites, differing in their land use and vegetation composition, one is dominated by grass species on an abandoned pasture (Pasture site), the other two are post-fire vegetation dominated by bracken (Bracken site) and various shrubs (Shrub site). Additionally, we assessed the effectiveness of manual removal of competitive herbaceous species to accelerate forest recovery. Monitoring was done in 2003, 2005 and 2007 on 48 subplots of 116 m2 each recording species richness and woody-species density. Results showed that the Pasture site demonstrated a competitive effect of exotic grasses on woody species recruitment with much lower species recruitment and density, suggesting serious inhibition of natural forest regeneration and an unclear successional trajectory. The Bracken and Shrub sites became significantly similar floristically and there is evidence for a marked facilitation of woody plant recruitment correlated with light availability on the ground. Both sites showed characteristics of classic succession, with Shrub showing a higher species richness and density while late-successional species are poorly represented on the Bracken site. However, NMDS ordination using species density showed that the two trajectories may not be converging towards a common ‘‘final state’’. Manual weeding was ineffective for accelerating forest recovery. These results suggest that the main limiting factor for the recruitment of woody species on the Pasture site is strong grass competition and must be addressed before seed availability, while seed availability seems to be theconstraining factor for Bracken and Shrub site development, thus direct seeding or planting may be effective in accelerating forest recovery.

Abstract:

Background: Tropical forests play an important role in the global carbon (C) cycle. However, tropical montane forests have been studied less than tropical lowland forests, and their role in carbon storage is not well understood. Montane forests are highly endangered due to logging, land-use and climate change. Our objective was to analyse how the carbon balance changes during forest succession. Methods: In this study, we used a method to estimate local carbon balances that combined forest inventory data with process-based forest models. We utilised such a forest model to study the carbon balance of a tropical montane forest in South Ecuador, comparing two topographical slope positions (ravines and lower slopes vs upper slopes and ridges). Results: The simulation results showed that the forest acts as a carbon sink with a maximum net ecosystem exchange (NEE) of 9.3 Mg C?(ha?yr)?1 during its early successional stage (0–100 years). In the late successional stage, the simulated NEE fluctuated around zero and had a variation of 0.77 Mg C?(ha?yr) –1. The simulated variability of the NEE was within the range of the field data. We discovered several forest attributes (e.g., basal area or the relative amount of pioneer trees) that can serve as predictors for NEE for young forest stands (0–100 years) but not for those in the late successional stage (500–1,000 years). In case of young forest stands these correlations are high, especially between stand basal area and NEE. Conclusion: In this study, we used an Ecuadorian study site as an example of how to successfully link a forest model with forest inventory data, for estimating stem-diameter distributions, biomass and aboveground net primary productivity. To conclude, this study shows that process-based forest models can be used to investigate the carbon balance of tropical montane forests. With this model it is possible to find hidden relationships between forest attributes and forest carbon fluxes. These relationships promote a better understanding of the role of tropical montane forests in the context of global carbon cycle, which in future will become more relevant to a society under global change.

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.

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.

Abstract:

Texture information from passive remote sensing images provides surrogates for habitat structure, which is relevant for modeling biodiversity across space and time and for developing effective ecological indicators. However, the applicability of this information might differ among taxa and diversity measures. We compared the ability of indicators developed from texture analysis of remotely sensed images to predict species richness and species turnover of six taxa (trees, pyraloid moths, geometrid moths, arctiinae moths, ants, and birds) in a megadiverse Andean mountain rainforest ecosystem. Partial least-squares regression models were fitted using 12 predictors that characterize the habitat and included three topographical metrics derived from a high-resolution digital elevation model and nine texture metrics derived from very high-resolution multi-spectral orthophotos. We calculated image textures derived from mean, correlation, and entropy statistics within a relatively broad moving window (102 m × 102 m) of the near infra-red band and two vegetation indices. The model performances of species richness were taxon dependent, with the lowest predictive power for arctiinae moths (4%) and the highest for ants (78%). Topographical metrics sufficiently modeled species richness of pyraloid moths and ants, while models for species richness of trees, geometrid moths, and birds benefited from texture metrics. When more complexity was added to the model such as additional texture statistics calculated from a smaller moving window (18 m × 18 m), the predictive power for trees and birds increased significantly from 12% to 22% and 13% to 27%, respectively. Gradients of species turnover, assessed by non-metric two-dimensional scaling (NMDS) of Bray-Curtis dissimilarities, allowed the construction of models with far higher predictability than species richness across all taxonomic groups, with predictability for the first response variable of species turnover ranging from 64% (birds) to 98% (trees) of the explained change in species composition, and predictability for the second response variable of species turnover ranging from 33% (trees) to 74% (pyraloid moths). The two NMDS axes effectively separated compositional change along the elevational gradient, explained by a combination of elevation and texture metrics, from more subtle, local changes in habitat structure surrogated by varying combinations of texture metrics. The application of indicators arising from texture analysis of remote sensing images differed among taxa and diversity measures. However, these habitat indicators improved predictions of species diversity measures of most taxa, and therefore, we highly recommend their use in biodiversity research.

Abstract:

To improve the current knowledge of the rainfall–runoff phenomena of tropical montane catchments, we explored the usefulness of several hydrological indicators on a nested cloud forest catchment (76.9 km2). The used metrics belong to 5 categories: baseflow mean transit time, physicochemical properties of stream water, land cover, topographic, and hydrometric parameters. We applied diverse statistical techniques for data analysis and to contrast findings. Multiple regression analysis showed that mean transit times of base flow could be efficiently predicted by sodium concentrations (higher during baseflows) and temperatures of stream water, indicating a major influence of geomorphology rather than topographic or land cover characteristics. Principal component analysis revealed that no specific subset of catchment indicators could be identified as prevailing descriptors for all catchments. The agglomerative hierarchical clustering analysis provided concomitant results, implying larger levels of dissimilarity between smaller subcatchments than between larger ones. Overall, results point out an intricate interdependence of diverse processes at surface and subsurface level indicating a high level of heterogeneity. Disregarding heterogeneity of nested or paired catchments could lead to incomplete or misleading conclusions, especially in tropical mountain regions where pronounced spatial and temporal gradients are present.

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.

Abstract:

Decomposition is a very important process. It is supporting nutrient cycles and for that reason crucial for the functionality of ecosystems. Various studies have shown that decomposition is driven by abiotic and biotic factors such as climate, seasonal weather conditions (like el Niño), soil organisms and disturbance of forests. In this study, the focus lies on investigating the impact of abiotic factors on the decomposition with a new simplified and standardised method, with tea bags as litterbags. Green tea bags were buried in two years, on different elevations between 1000 m a.s.l. and 3000 m a.s.l. in 500 m steps on disturbed and undisturbed plots in the Ecuadorian Andes. After 21 days in the soil, the decomposition rate were calculated and compared on different elevations and different disturbances in two different years. The disturbance had no effect, because the disturbed plots were fragmented and the study took place in the interior of these fragments; here no edge effects influenced the decomposition rate. As expected, the decomposition rate declined with an increase in elevation, due to changing climate conditions. In the lower, wet and warm elevations, it was faster than in the higher elevation where the climate is wetter but also colder. In the test series from 2015, the decomposition rate was higher in the upper elevations than in 2014, this could be explained by a weather phenomenon called el Niño, which took place in 2015. It leads to a slightly higher temperature and 60% more precipitation than what normally would be expected in 2015. These differences between the two years show the importance of taking seasonal and annual variations into account while investigating decomposition and the sensitivity of this important ecosystem process to changing weather and climate conditions.

Abstract:

Climate change and forest degradation are major threats to forest ecosystems. The climatic changes can affect the mineralization rate in soils and therefore change the amount of available nitrogen components for plants. Thus these changes can influence foliar C/N-ratio. Previous studies used an elevation gradient to test the influence of climatic changes on ecosystems, and showed that foliar C/N-ratio is positively correlated with elevation. Changes in foliar C/N-ratio may affect the feeding behavior of insect herbivores and therefore influence leaf area loss (LAL). LAL is used as an indicator of herbivory and therefore may consequently also be related to ant abundance because ants prey on insect herbivores. Ants in return, are also affected by the abiotic changes with increasing elevation and therefore sensitive to climate change. However, forest degradation is currently the greater threat to ecosystems. Degradation can lead to changes in the nutrient uptake of plants and therefore to changes in foliar C/N-ratio. Moreover it can reduce ant abundance as ants are sensitive to the conversion of forests. We nalyzed the causal effects of abiotic factors (elevation and degradation) on biotic factors (foliar C/N-ratio and ant activityabundance) and the relationships between the biotic factors and LAL with linear mixed-effect models in a path model. We found a significant positive correlation between foliar C/N-ratio and elevation, and a significant negative correlation between ant activity-abundance and elevation. Foliar carbon-content had a significant negative correlation with degradation. Our results revealed no significant relationships with LAL, but LAL correlated negatively with foliar C/N-ratio in the shrub layer. The results of our study point out that foliar C/N-ratio and ant activityabundance change with elevation and thus respond to climatic changes. Moreover our results indicate that foliar C/N-ratio can be connected to LAL, but that influences such as the abundance and distribution of insect herbivores along elevation should be examined closely. Our finding that foliar C/N-ratio, ant activity-abundance and LAL were unaffected by degradation indicates that the studied degraded forests are still suitable habitats for insect herbivores and ants.

Abstract:

Biodiversity monitoring is a global need due to environmental degradation and climate change. Birds are often monitored indicators for environmental health because they are easy assessable, fast reacting species, which supply important ecosystem services. But conventional biodiversity monitoring can be timeconsuming, invasive and it often needs trained specialists, thus appropriate alternatives, especially for largescale assessments, like acoustic monitoring are needed. While numerous acoustic indices were generated no studies occur about their ability to reflect conventional alpha-diversity measures such as species richness, abundance, diversity or evenness under complex conditions like a gradient of elevation and degradation. We choose bird communities along an elevation gradient in natural and degraded rainforests in a highdiverse region in the Ecuadorian Andes to investigate the association among five conventional (total abundance, species richness, Shannon Index, evenness, Gini Index) and three acoustic (Acoustic Diversity Index [ADI], Bioacoustic Index [BI], Acoustic Evenness Index [AEI]) alpha-diversity measures. Furthermore, we investigated the influence of higher resolutions (FFT window size, frequency band size) on the acoustic indices. Further, we tested a new acoustic beta-diversity measure. With help of multivariate analyzes we found acoustic diversity measures were not significantly correlated with conventional diversity measures in high-diverse rainforests. The acoustic indices were correlated between another. The values of the acoustic indices increased with higher resolutions and were strongly positively correlated with their next higher resolution. The NMDS of the conventionally assessed bird communities resulted an elevation gradient and a distinct separation between degraded and natural forest communities. The NMDS of the acoustically assessed bird communities resulted no distinct gradients. The conventional and acoustic alpha-diversity measures were not significantly associated with the elevation or habitat type. ADI, BI and AEI seem not appropriate to reflect conventional diversity measures in high-diverse ecosystems, but BI can reflect avian abundance in less diverse ecosystems. Avian acoustic activity was driven by noisy species and not by species richness or abundance. Higher resolutions of the acoustic indices did not resolute acoustic activity more exactly in this case, thus for communities where birds with long or complex calls (relevant for BI) or narrow frequency ranges (relevant for ADI/AEI) are not dominating the acoustic activity the default resolutions of the acoustic indices seem sufficient. Acoustic beta-diversity assessment seems problematic because the analyzes of frequencies does not reflect species turnover among communities due to the reason that several species can occupy the same frequencies with their calls.

Abstract:

Environmental stressors and changes in land use have led to rapid and dramatic species losses. As such, we need effective monitoring programs that alert us not only to biodiversity losses, but also to functional changes in species assemblages and associated ecosystem processes. Ants are important components of terrestrial food webs and a key group in food web interactions and numerous ecosystem processes. Their sensitive and rapid response to environmental changes suggests that they are a suitable indicator group for the monitoring of abiotic, biotic, and functional changes. We tested the suitability of the incidence (i.e. the sum of all species occurrences at 30 baits), species richness, and functional richness of ants as indicators of ecological responses to environmental change, forest degradation, and of the ecosystem process predation on herbivorous arthropods. We sampled data along an elevational gradient (1000–3000 m a.s.l.) and across seasons (wetter and drier period) in a montane rainforest in southern Ecuador. The incidence of ants declined with increasing elevation but did not change with forest degradation. Ant incidence was higher during the drier season. Species richness was highly correlated with incidence and showed comparable results. Functional richness also declined with increasing elevation and did not change with forest degradation. However, a null-model comparison revealed that the functional richness pattern did not differ from a pattern expected for ant assemblages with randomly distributed sets of traits across species. Predation on artificial caterpillars decreased along the elevational gradient; the pattern was not driven by elevation itself, but by ant incidence (or inter-changeable by ant richness), which positively affected predation. In spite of lower ant incidence (or ant richness), predation was higher during the wetter season and did not change with forest degradation and ant functional richness. We used path analysis to disentangle the causal relationships of the environmental factors temperature (with elevation as a proxy), season, and habitat degradation with the incidence and functional richness of ants, and their consequences for predation. Our results would suggest that the forecasted global warming might support more active and species-rich ant assemblages, which in turn would mediate increased predation on herbivorous arthropods. However, this prediction should be made with reservation, as it assumes that the dispersal of ants keeps pace with the climatic changes as well as a one-dimensional relationship between ants and predation within a food-web that comprises species interactions of much higher complexity. Our results also suggested that degraded forests in our study area might provide suitable habitat for epigaeic, ground-dwelling ant assemblages that do not differ in incidence, species richness, functional richness, composition, or predation on arthropods from assemblages of primary forests. Most importantly, our results suggest that the occurrence and activity of ants are important drivers of ecosystem processes and that changes in the incidence and richness of ants can be used as effective indicators of responses to temperature changes and of predation within mega-diverse forest ecosystems.

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.

Abstract:

Increasing land-use conflicts call for the development of land-use systems that reconcile agricultural production with the provisioning of multiple ecosystem services, including climate change mitigation. Agroforestry has been suggested as a global solution to increase land-use efficiency, while reducing environmental impacts and economic risks for farmers. Past research has often focused on comparing tree-crop combinations with agricultural monocultures, but agroforestry has seldom been systematically compared to other forms of land-use diversification, including a farm mosaic. This form of diversification mixes separate parcels of different land uses within the farm. The objective of this study was to develop a modelling approach to compare the performance of the agroforestry and farm mosaic diversification strategies, accounting for tree-crop interaction effects and economic and climate uncertainty. For this purpose, Modern Portfolio Theory and risk simulation were coupled with the process-based biophysical simulation model WaNuLCAS 4.0. For an example application, we used data from a field trial in Panama. The results show that the simulated agroforestry systems (Taungya, alley cropping and border planting) could outperform a farm mosaic approach in terms of cumulative production and return. Considering market and climate uncertainty, agroforestry showed an up to 21% higher economic return at the same risk level (i.e. standard deviation of economic returns). Farm compositions with large shares of land allocated to maize cultivation were also more severely affected by an increasing drought frequency in terms of both risks and returns. Our study demonstrates that agroforestry can be an economically efficient diversification strategy, but only if the design allows for economies of scope, beneficial interactions between trees and crops and higher income diversification compared to a farm mosaic. The modelling approach can make an important contribution to support land-use decisions at the farm level and reduce land-use conflicts at the landscape level.

Abstract:

Postulating that megadiverse forests are more profitable than monocultures lacks economic evidence and may put conservation incentives at risk. Letter in Response to Liang et al. published in Science on October 14

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.

Abstract:

Human influence and its impacts are perceptible in all ecosystems resulting in land transformation, changes in global biogeochemistry, climate change, and loss of biological diversity. Mapping the spatial and temporal patterns of human influence is essential to address land use management and conservation programs. In this study, we tailored the Human Footprint index (HF) developed at global level to evaluate the spatial and temporal patterns of human pressure in South Ecuador for 1982, 1990 and 2008. Landscape and ecosystem levels were analyzed to identify the contribution of different human proxies to the HF.We also used the HF to evaluate the effectiveness of protected areas to reduce human pressure in the surrounding landscape. We found that levels of human pressure increased and the wildest areas decreased since 1982. We identified important “hotspots of changes” in the seasonally dry forests in the western part and the premontane evergreen forest in the eastern part of the study area. Our results show that each human proxy contributes in a different way to the observed values of HF in the studied ecosystems. Finally, we found that Podocarpus NP, the most important protected area in our study region, seems to be partially effective in reducing human pressure inside and in the buffer zones where only a low increase in HF was detected. However, the HF values observed in the surrounding landscape were higher than those observed in the buffer zone and inside the protected area. We demonstrated that HF could be a useful regional evaluation tool to facilitate conservation planning.

Abstract:

In einem tropischen Bergregenwaldgebiet in Ecuador, haben verschiedene Forschungsarbeiten gezeigt, dass auch Mikronährelemente einen Einfluss auf die mikrobielle Aktivität haben können. Mittels eines Inkubationsversuches mit einer Streuauflagenprobe aus dem Untersuchungsgebiet, wurde analysiert ob eine multiple Mikronährlimitierung von Mikroorganismen vorliegt. Dabei wurde die Streuprobe in einem sechs Tage dauernden Inkubationsversuch täglich mit verschiedenen Mikronährelementen (Cu, Mo, Mn, Zn, P)gedüngt. Danach wurde die Nährlösung abgesaugt und die daraus entstandenen Eluate mithilfe eines Flammen-Atomabsorptionsspektrometer auf die verbliebenen Metallgehalte analysiert. Zuverlässige Werte konnten nur für Cu, Mn und Zn gemessen werden, die Werte für Mo und P lagen unter der Nachweis- oder Bestimmungsgrenze. Bei der Kupfermessung konnte die höchste Kupferkonzentration in der Cu-gedüngten Probe gemessen werden, doch es wurde schon weniger Cu ausgewaschen, wenn zusätzlich mit einem anderen Mikronährelement gedüngt wurde als in den Kontrolldüngungen. Für Mn wurde in der Kontrolllösung die höchste Mn-Konzentration gemessen, in allen anderen Proben mit zusätzlicher Düngung wurde Mn stärker zurückgehalten. Die gemessene Zn-Konzentration bei Düngung mit Cu, Mn, Mo und P lag fast bei null. Zink wurde sehr stark zurückgehalten. Auch in der Zink-Gedüngten Probe wurde Zn in den ersten drei Tagen stark zurückgehalten und wurde erst danach stärker ausgewaschen als in den Kontrollproben. Aufgrund der Resultate ist zu erkennen, dass auch Mikronährelemente eine limitierende Wirkung auf Mikroorganismen haben können und die Mikroorganismen im untersuchten Gebiet durch verschiedene Mikronährelemente limitiert sind.

Abstract:

Growth limitation induced by Al toxicity is believed to commonly occur in tropical forests, although a direct proof is frequently lacking. To test for the general assumption of Al toxicity, Al, Ca, and Mg concentrations in precipitation, throughfall, stemflow, organic layer leachate, mineral soil solutions, stream water, and the leaves of 17 native tree species were analyzed. We calculated Al fluxes and modeled Al speciation in the litter leachate and mineral soil solutions. We assessed potential Al toxicity based on soil base saturation, Al concentrations, Ca:Al and Mg:Al molar ratios and Al speciation in soil solution as well as Al concentrations and Ca:Al andMg:Al molar ratios in tree leaves. High Al fluxes in litterfall (8.77±1.3 to 14.2±1.9 kg ha?1 yr?1, mean ± SE) indicated a high Al circulation through the ecosystem. The fraction of exchangeable and potentially plant-available Al in mineral soils was high, being a likely reason for a low root length density in the mineral soil. However, Al concentrations in all solutions were consistently below critical values and Ca:Al molar and the Ca2+:Alinorganic molar ratios in the organic layer leachate and soil solutions were above 1, the suggested threshold for Al toxicity. Except for two Al-accumulating and one non-accumulating tree species, the Ca:Al molar ratios in tree leaves were above the Al toxicity threshold of 12.5. Our results demonstrate high Al cycling through the vegetation partly because of the presence of some Al accumulator plants. However, there was little indication of an Al toxicity risk in soil and of acute Al toxicity in plants likely reflecting that tree species are well adapted to the environmental conditions at our study site and thus hardly prone to Al toxicity.

Abstract:

The forests of South Ecuador have high conservation value because they are highly threatened, but also possess high diversity and endemism levels. However, as the process of conservation is inherently spatial, the little available information about the factors that promote vulnerability of these forests as well as the spatial distribution of the conservation targets have produced some conservation pitfalls. The main objective of this dissertation was to generate spatial information about the threats and biological values occurring in this region to prioritize areas for conservation. The second chapter analyzes the deforestation and fragmentation patterns in the region since the 1970s using aerial photographs and satellite images to identify areas with remaining forest, fronts of deforestation, annual deforestation rates and the dynamics in the composition and configuration of the landscape of South Ecuador. We recorded annual deforestation rates of 0.75% (1976 – 1989) and 2.86% (1989 – 2008) for two consecutive survey periods. Also, we found that South Ecuador is experiencing an ongoing fragmentation process due to an increase in the number of patches, a decrease in mean patch size and an increase in the isolation of forest fragments. This study also contributes to a better understanding of forest change dynamics in the tropics. We found that substantial portions of natural forests are being degraded or converted into pastures and that main fronts of deforestation are located in the lowest areas in the premontane evergreen forest. The third chapter describes the temporal and spatial patterns of human pressure, as it is one of the main factors that influence the effectiveness of conservation strategies. At local scale, we adapted at local scale the Human Footprint Index (HF) developed by Sanderson et al. (2002), to evaluate spatial changes in HF during a 26 year period at both landscape and ecosystem levels. This information allowed us to identify “hotspots of change” and the wildest areas remaining in order to evaluate how different human proxies contribute to HF and to demonstrate how effective the most important protected areas have been in reducing human pressure inside and outside their boundaries. The findings show a noticeable 4 increase in human pressure levels in South Ecuador and a progressive reduction in the wildest areas. We also identified that the important “hotspots of changes” are located in the western region and the Rio Zamora river basin. The most impacted vegetation types were seasonally dry forest and shrubland. Here, population density is the human proxy with the highest contribution to the observed patterns. Finally, we found that Podocarpus National Park has been partially effective in reducing human pressure inside and outside its borders. HF levels have increased inside and outside the boundaries of the protected area, but the human pressure was always lower than that observed in the surrounding landscape. The fourth chapter analyzes the patterns of alpha and beta diversity of endemic plant species to evaluate the congruence of both patterns and to identify areas with the highest diversity of endemic plants in order to prioritize areas for conservation. We found that hotspots of alpha diversity are concentrated along the Andes, but this diversity was only slightly congruent with beta diversity patterns of endemic plants mostly concentrated in the western and eastern escarpments of the Andes, and in the Coastal and Amazon cordilleras. We also found that approximately 40% of the areas with the highest alpha and beta diversities have already disappeared due to deforestation and that only 30% is under protection in Ecuador. Thus, we propose 12 potential areas with a high priority of conservation mostly located in South Ecuador to improve the representativeness and complementarity of the current reserve network. Finally, the fifth chapter synthesizes the principal findings of this thesis highlighting the implications for conservation and suggesting potential areas to be preserved based on human pressure levels, remaining forest and alpha and beta diversity patterns of endemic plants.

Abstract:

Anthropogenic activities have produced changes in natural ecosystems worldwide. In tropical regions in South America, industrialization of cities and forest clearance via burning are the main activities releasing pollutants into the atmosphere and inducing changes in nutrient deposition patterns and climate of primary forests. Nitrogen (N) and phosphorus (P) are considered the main limiting nutrients of plant growth since their availability is vital for net primary productivity. Therefore, any change in N or P availability in soils would likely alter important mechanisms of forests dynamics such as growth and survival. Changes in soil pH (acidity), nutrient cycles and altered nutrient stocks affect N and P availability and affect various physiological processes of trees. Although low levels of nutrient deposition have been reported for montane forests in southern Ecuador (ca. 5 kg ha–1 for N, 0.49 kg ha–1 for P), even these levels are expected to lead to changes in forest structure and dynamics over the long term. The responsiveness of forest to changes in resource availability varies with forest age and successional status, as well as life stage of the plant. Young plants (tree seedlings) should be more responsive to changes in nutrient availability than mature forest trees. Further, any demographic response is more likely to be visible in seedlings before mature trees because of the more rapid dynamics of seedlings. Therefore, I studied the regeneration dynamics of montane forest to understand which nutrient-related processes are involved in the growth and establishment of seedlings at both the individual and community levels. The Ecuadorian NUtrient Manipulation EXperiment (NUMEX) has been designed to study the response of montane forest to moderate fertilization. The experiment has been set up over an elevation range across three main study sites (1000 m. a.s.l: Bombuscaro; 2000 m. a.s.l: San Francisco; 3000 m. a.s.l: Cajanuma) within the Podocarpus National Park and San Francisco Reserve. The factorial experiment consists of four blocks containing four experimental plots (N, P, NP and control) in every study site (16 plots per elevation). Fertilization has been done since 2008, adding moderate quantities of fertilizer (50 kg ha–1 y–1 of N and/or 10 kg ha–1 y–1 of P). Three different approaches were used to assess the seedling community and common species responses to fertilization. First, the seedling community was monitored in natural forest at 2000 m over three consecutive years (2011 – 2013). In 192 monitoring subplots (1m2 each) in San Francisco, all seedlings and saplings were mapped and tagged. Measurements of height, diameter, herbivory and leaf production were recorded for all individuals, and the number of recruited and dead seedlings was counted every year. Second, allocation patterns and stoichiometry of seedlings of the six most common species were determined across the elevation gradient. Naturally occurring seedlings of the following species were harvested: Clarisia racemosa and Pouteria torta in Bombuscaro, Graffenrieda emarginata and Palicourea angustifolia in San Francisco and Grafferieda harlingii and Hedyosmum purpuracens in Cajanuma. Morphology (biomass allocation, herbivory and foliar areas such as SLA, LAR and LA) and foliar stoichiometry (nutrient contents and N:P ratios) were recorded and analyzed. Third, a reciprocal transplantation experiment (STE) within the NUMEX experimental plots monitored seedlings of the most common species in Bombuscaro, (Pouteria torta), to assess specific responses in seedling performance over one year. These three levels of analysis showed differential responses of the species community and common species to fertilization. Contrary to lowland forests, the community seedlings in this montane forest showed a moderate response. The density of seedling individuals decreased following nutrient addition, as a result of lower recruitment in treatments plots, but mortality was unaffected. Consequently, density-dependent mechanisms activated by additional N uptake did not show evidence of being a main driver to changes in species density. The community of seedlings did not show significant growth in response to fertilization although seedlings were higher in the N treatment. However, N addition increased herbivory over all seedlings and plots, which could have masked other seedlings growth responses. Common species seem to be well adapted to the relatively poor soils since these species were not favored by nutrient addition showing no change in growth or leaf traits. Over the long-term, common species might lose their dominance by being less competitive than faster growing species. However, it would need a longer period of monitoring under continued fertilization to produce visible shifts in community composition. Species-specific responses are hard to determine in such species rich communities. Therefore, analyses of the six common species were conducted to complement the community-level study. Leaf morphology and foliar stoichiometry were assessed from harvested seedling from the experimental plots. Both N and P had effects on seedling traits, suggesting co-limitation of N and P in montane tree species in all elevations. However, foliar N:P ratios and the more frequently response to P addition indicated this nutrient might be more limiting than N along the gradient. Responsiveness of the studied species varied between the six species. Stronger foliar P concentration compared with N in all species but Pouteria torta suggested higher P consumption in montane forest species, similar to the responses of several other tropical plant species after P addition. Increased herbivory was only evident in the opposite responses of G. emarginata (N and N+P addition) and P. angustifolia (P addition) at 2000 m suggesting that plant selection by herbivores is driven by resource quality. Most of the species had higher belowground biomass in root fractions following fertilization, except for G. harlingii at 3000 m, the only species that showed significant increase in aboveground biomass after nutrient addition. Pouteria torta seedlings showed no significant changes in species performance after fertilization one year after establishment of the STE. Pouteria seems to be well-adapted to poor soils, since N and P addition did not alter foliar nutrient concentrations. Nevertheless, N and N+P addition significantly increased mortality and diameter growth rates. P addition resulted in higher leaf area loss and shifted carbon allocation to root growth. These responses indicated consequences in the competitive strength in the understory and recruitment success of Pouteria torta. However, the ambiguous response in some attributes (growth and herbivory) not related with mortality made it difficult to predict the future abundance of this species in long term. In conclusion, complementary studies demonstrated that specific nutrient limitation for N or P in montane species seem not to be a rule in rich species ecosystems although nutrient addition did alter some pattern of growth and survival. Thus, nutrient fertilization might affect various mechanisms and dynamics of plant communities, the balance of which will only play out over long time scales.