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

Abstract:

“There is, however, one natural feature of this country, the interest and grandeur of which may be fully appreciated in a single walk: it is the “virgin forest”. Here no one who has any feeling of the magnificent and the sublime can be disappointed.” Alfred Russel Wallace commented with these words on the wonders of the rain forest covering the Amazon Basin. If he had travelled further up, right to the origins of the Amazon, to the far-off places of Andean headwater streams, he would have encountered a forest ecosystem even more wondrous and unique – the montane cloud forest (Figure 1-1). The Merriam Webster dictionary defines cloud forests rather shortly as “wet tropical mountain forests at an altitude usually between 3000 and 8000 feet (1000 and 2500 meters) that are characterized by a profusion of epiphytes and the presence of clouds even in the dry season” (Merriam-Webster 2003). During the first international symposium on cloud forests in Puerto Rico in 1993, a more explicit collection of characteristics was put together (Hamilton et al. 1993). Here, the ecosystem is defined as having: - a distinctly floristic and structured form - an atmospheric environment with persistent cloud cover - reduced solar radiation - suppressed evapotranspiration - enhanced net throughfall input due to the stripping of clouds by the tree canopies - reduced canopy heights and gnarled tree trunks at higher altitudes - a large epiphyte biomass - wet and frequently waterlogged soils with a high organic content - extremely high biodiversity (a so-called biodiversity hotspot) - a high amount of endemism. Cloud forests are found all around the world (see Figure 1-2), far inland or on islands, and at altitutes ranging from as low as 500 m up to 3500 m (Hostettler 2002). Although only 2.5 % of the world’s tropical forests are cloud forests (Bubb et al. 2004) they are outstandingly important for sustaining life on our planet. A myriad of plants have evolved depending upon the constant fog and hundreds of animals have evolved to depend on these plants. Numerous plant species have been found to possess medicinal qualities and contribute to the health of a multitude of people each year. For example quinine, the cure for malaria, is extracted from the bark of the Cinchona tree, which was first discovered in the montane cloud forests of Peru (Régnier 2007). Other essential ecosystem services provided by cloud forests are the formation of soil, carbon sequestration, the cycling of nutrients and recreation among others (Costanza et al. 1997). The key function of cloud forest, though, is the provision of high amounts of good quality freshwater. Downstream populations depend on this provision of drinking and irrigation water, an important part of which is captured by the stripping of clouds by tree canopies. Even during drier periods, pristine cloud forests supply a reliable stream flow by draining the water which is abundantly stored in the forest vegetation and soil. Several large tropical capitals such as Quito, Tegucigalpa and Mexico city are dependent on this water and are thus intertwined with the fate of these watersheds (Hostettler 2002). Not without reason around 90 % of the world’s cloud forest sites are included in the WWF Global200 region list with conservation priority (Aldrich et al. 2000). Despite their importance, tropical forests all over the world are deforested at an overwhelming rate. The average annual deforestation rate for tropical forests in South America has been estimated to be 0.4 % for the year 2000. Amongst all South American countries, Ecuador has by far the highest deforestation rate with a lessening of the country’s forest cover of 1.2 % per year (FAO 2001). Reasons for deforestation are various, but are generally caused by population growth or shifts. The most widespread threat to tropical cloud forests is forest clearance for farming or pastures. In some countries hunting, forest fires and mining are also responsible for forest conversion or degradation. However, one of the most prevalent pressures on lowland rainforests, namely timber harvesting, is not such a big issue for cloud forests due to the mostly steep topography, and the reduced tree heights at these altitudes (Bubb et al. 2004). Even though the intrinsic and economic values of cloud forests are widely acknowledged, our understanding of the drivers of ecosystem functioning is still deficient. Sadly, the scarce knowledge about these fragile systems poses a hindrance for effective conservation management and future policy decisions (McClain & Naiman 2008).

Abstract:

Der fortschreitenden Vernichtung megadiverser tropischer Bergregenwälder kann nur durch Wiederaufforstung mit indigenen Arten nachhaltig entgegengewirkt werden. Das dafür benötigte Pflanzmaterial wird zum Großteil durch vegetative Vermehrung gewonnen. Dieses Buch liefert bisher noch ausstehendes Grundlagenwissen, indem es die Zusammenhänge zwischen dem Bewurzelungspotenzial und der Physiologie von mehreren, in den ecuadorianischen Anden beheimateten Baumarten beleuchtet. Insbesondere wurden dafür lösliche Zucker, Stärke, die Phytohormone Auxin und Cytokinin sowie die stomatäre Leitfähigkeit analysiert. Außerdem werden die Ergebnisse umfassender Vermehrungsexperimente mit Stammstecklingen und Mooslingen detailliert dargestellt. Für den Praktiker werden die Erkenntnisse in ausführlichen und unter einfachen Bedingungen umsetzbaren Klonierungsprotokollen für die beiden Arten Heliocarpus americanus und Tabebuia chrysantha aufbereitet. Im Besonderen wird das Stressen der Mutterpflanzen als bislang kaum genutztes Werkzeug zur Einflussnahme auf den Inhaltsstoffwechsel bei der Stecklingsvermehrung vorgestellt.

Abstract:

Impacts of different terrain configurations on the general behaviour of idealised katabatic flows are investigated in a numerical model study.Various simplified terrain models are applied to unveil modifications of the dynamics of nocturnal cold drainage of air as a result of predefined topographical structures. The generated idealised terrain models encompass all major topographical elements of an area in the tropical eastern Andes of southern Ecuador and northern Peru, and the adjacent Amazon. The idealised simulations corroborate that (i) katabatic flows develop over topographical elements (slopes and valleys), that (ii) confluence of katabatic flows in a lowland basin with a concave terrainline occur, and (iii) a complex drainage flow system regime directed into such a basin can sustain the confluence despite varying slope angles and slope distances.

Abstract:

The multidisciplinary research unit “Biodiversity and Sustainable Management of a Megadiverse Mountain Ecosystem in South Ecuador” established a central data management system to provide the members with all gathered scientific data. Additionally to the database functionality of the system the web based layout is capable to present general information on the research unit to the public and support accounting and administration of the project. All parts of the system are implemented using open-source or free software. A major task is the allocation of a sophisticated and detailed metadata scheme. The standardised ecological metadata language (EML) is used as the basis for metadata information stored in a relational database. The describing datatypes are highly modular and can be expanded if necessary. Data input and searching is implemented through a dynamic webinterface with easy to use forms. This is important to increase the acceptance by the users of the system. Searching the database is possible by strings for keywords, authors, etc. or by geographic locations. Except for gridded data, all single values of the datasets are stored in relational tables and thus, it is possible to extract only parts of a whole dataset during data download. While the system is already operational, modifications and new features are continuously implemented.

Abstract:

Mycorrhizas of vascular plants and mycorrhiza-like associations of liverworts are integral parts of terrestrial ecosystems, but have rarely been studied in tropical mountain rain forests. Our lightand electron microscopical studies at the RBSF revealed that the roots of nearly all tree species were well colonized by structurally diverse arbuscular mycorrhizal Glomeromycota (Haug et al. 2004, Beck et al. 2005), a few tree species by ectomycorrhizal Ascoand Basidiomycota (Haug et al. 2005), and that epiphytic, pleurothallid orchids formed mycorrhizas with Tulasnella species and members of the Sebacinales (Basidiomycota) (Suárez et al. 2006, Kottke et al. 2007). Species of Sebacinales also occurred in mycorrhizas of hemiepiphytic ericads (Setaro et al. 2006) and Tulasnella species were found in liverworts belonging to the Aneuraceae (Kottke et al. 2007). Traditionally, studies on biodiversity and host specificity have been based on morphologically defined species. No such approach was feasible in the case of the mycobionts in our study as the fungi did not display sufficient structural differences in the mycorrhizas for delimitation of morphospecies. The identification of the mycorrhiza-forming fungi in the forest could be done neither by spore nor by fruiting-body sampling, as both methods would have yielded only a very narrow spectrum of the fungal communities (Husband et al. 2002, Sanders 2004a). Instead, direct sequencing of the associated fungi from the plant material was carried out (Kottke et al. 2007). Given our present stage of knowledge, the sequence types (ribosomal genotypes) can rarely be precisely related to either morphological or biological species. However, the amount of information derived from the sequences of the ribosomal genes appeared to be meaningful in previous ecological studies on arbuscular mycorrhizas (Helgason et al. 2002, Husband et al. 2002, Sanders 2004b) as well as on mycorrhiza-forming Basidiomycota (Bidartondo et al. 2003, Bidartondo et al. 2004). However, analysis of biodiversity and specificity of the mycobionts from field samples using DNA sequences also poses problems. Firstly, results are limited by the available primers. Secondly, problems resulted from the observation that the ribosomal genes can show intraspecific variation, especially in the case of the multinucleate Glomeromycota (Sanders et al. 1995, Lloyd-Macgilp et al. 1996, Clapp et al. 2001, Sanders 2004b). These facts pose general, unresolved challenges to a species concept based on meaningful levels of genetic diversity. Thus the list of fungal sequences presented here is far from being complete and far from being a species list.

Abstract:

Soil landscape modelling is based on understanding the spatial distribution patterns of soil characteristics. A model relating the soil?s properties to its position within the landscape is used to predict soil properties in other similar landscape positions. To develop soil landscape models, the interaction of geographic information technology, advanced statistics and soil science is needed. The focus of this work is to predict the distribution of the different soil types in a tropical mountain forest area in southern Ecuador from relief and hydrological parameters using a classification tree model (CART) for soil regionalisation. Soils were sampled along transects from ridges towards side valley creeks using a sampling design with 24 relief units. Major soil types of the research area are Histosols associated with Stagnosols, Cambisols and Regosols. Umbrisols and Leptosols are present to a lesser degree. Stagnosols gain importance with increasing altitude and with decreasing slope angle. Umbrisols are to be found only on slopes <30°. Cambisols occurrence might be related to landslides.The CART model was established by a data set of 315 auger sampling points. Bedrock and relief curvature had no influence on model development. Applying the CART model to the research area Histosols and Stagnosols were identified as dominant soil types. Model prediction left out Cambisols and overestimated Umbrisols, but showed a realistic prediction for Histosols, Stagnosols and Leptosols.

Abstract:

From July to October 2009 different methods for the measurement of suspended sediment yield and related particulate carbon (C) and nitrogen (N) loss were investigated in a mountainous cloud forest catchment in South-Ecuador. Humid mountainous regions in the tropics are often characterized by highly variable discharge, high rainfall erosivity and geomorphic instability which result in a greatly increased erosion risk. Additionally this danger is enhanced in the studied catchment by the conversion of cloud forests to pasture and crop land as well as landslides caused by road construction. To be able to quantify suspended sediment yield and the associated particulate organic carbon (POC) and nitrogen (NOC) export, a direct approach of suspended sediment sampling, gravimetric ascertainment of the quantity and C and N analysis was combined with the application of two different turbidity sensors. The first one, a ViSolid sensor (WTW, Weilheim, Germany), was set up at the catchment outlet. The second one, a TSS Portable sensor (Hach Lange, Düsseldorf, Germany), was used as a mobile hand held unit. Relations from correlation and regression analysis between suspended sediment concentration and discharge and turbidity respectively made it possible to calculate first extrapolations of yearly suspended sediment yield between 26,5 t ha-1 and 46,3 t ha-1. These numbers are clearly below the global average of 200 t suspended sediment ha-1 a-1. For POC export, the results were between 272,8 kg ha-1 a-1 and 446,9 kg ha-1 a-1 and for NOC export between 21,2 kg ha-1 a-1 and 34,7 kg ha-1 a-1. The PON value fits to literature data whereas POC value is above literature data. The differing results and the unexpected low suspended sediment yield can be explained by the fact that more data integrating the temporal variation of suspended sediment discharge during the year are needed for an adequate calculation. Furthermore emphasis to a greater extent should be placed on the improvement of the data calibration for the ViSolid sensor.

Abstract:

Ziel dieser Arbeit war es, ein Licht auf die Zusammenhänge zwischen Landnutzung, den Habitateigenschaften im Gewässer und den lokalen Makroinvertebratengemeinschaften zu werfen. Dazu wurden Proben des Makrozoobenthos genommen und zahlreiche Umweltvariablen erfasst. Anschließend wurde mit univariater und multivariater Statistik herausgearbeitet, welche Faktoren die Verbreitung von Wirbellosen wesentlich steuern. Die zwei vorherrschenden Landnutzungstypen der Weidebewirtschaftung und Waldnutzung mit geringer Eingriffsintensität unterscheiden sich signifikant in ihrem Einfluss auf die Fließgewässer im Grad der Beschattung, Vbase, pH-Wert, EC und Alkalinität. Die CCA zeigt, dass die Faunastruktur, neben diesen Parametern, stark mit dem Substrattyp korreliert ist. Dies spiegelt sich auch in der aquatischen Wirbellosenfauna wider. Insgesamt sind 44% der gefundenen Taxa in ihrer Verbreitung auf eine Landnutzungsform beschränkt. Typische Taxa in Einzugsgebieten mit extensiver Viehwirtschaft und geringer Bewaldung sind Blephariceridae gen.1, Empididae, Macrostemum, Petrophila, Phanocerus, Psychodidae gen. 1, Tabanidae, Andesiops, Haplohyphes, Baetodes, Leptohyphes, Smicridea und Thraulodes. Diese Makroinvertebraten bevorzugen vor allem hohe Werte für EC, pH, Alkalinität und Vbase. In Fließgewässern mit angrenzendem Wald ist die absolute Taxazahl und Eveness höher. Die Individuendichte ist geringer. Die Diversitätsindizes von Shannon-Wiener, Margalof oder Simpson ergeben in der Summe keine deutlichen Unterschiede zwischen den Landnutzungstypen. In Fließgewässern mit angrenzendem Wald sind Hetaerina, Polythore, Argia, Atanatolica, Farrodes, Phylloicus, Bezzia, Molophilus, Cernotina und Sialis typische Vertreter des Makrozoobenthos. Die entscheidenden Parameter sind für diese Taxa ein hoher Grad an Beschattung, viel Feinsubstrat und eine geringe Vbase. Vor allem die Ordnung der Odonata wäre bei weiterer Abholzung der Wälder im Untersuchungsgebiet bedroht.

Abstract:

The montane forests of Ecuador are part of one of the world?s hotspots of biodiversity and they also suffer the highest deforestation rate amongst South American countries. The processes that drive the dynamics of these highly diverse ecosystems are poorly understood. This is particularly true for transient dynamics, which are crucial for the protection and sustainable management of such forests. Dynamic simulation models can be used to analyse the growth of forests, but so far they have been applied mostly to temperate forests and to some few tropical lowland forests. In this study we investigate whether a process-based, individual-oriented simulation model like FORMIND is capable of reproducing the dynamics of tropical montane forests. For this purpose we develop a parameterisation for the model and validate the model against field observations of different (structural) patterns. We then analyse the predicted succession dynamics. The model is capable of reproducing the structure and dynamics of mature ridge forest on different levels of complexity. The main results indicate that, in terms of relative abundances of different species groups and stem size distribution in the tree community, our model predicts the observed patterns in the field. Additional field studies and model modifications are required to simulate the succession processes that follow different types of disturbances. FORMIND is a promising tool for the extrapolation of local measurements and for simulating the dynamics of tropical montane forests. Parameterisations of the model for further forest types within the research area are intended. The model has a number of potential applications, ranging from investigating the impact of (different) natural disturbances on forest structure and tree species diversity to analysing different potential management strategies.

Abstract:

The thermal structure of a megadiverse mountain ecosystem in southern Ecuador is examined on the basis of temperature measurements inside the natural mountain forest and at open-sites along an altitudinal gradient from 1600 to 3200 m. The main methodological aim of the current study is to develop an air temperature regionalization tool to provide spatial datasets on average monthly mean, minimum and maximum temperature by using observation data. The maps, based on data of the period 1999?2007, are needed by ecological projects working on various plots where no climate station data are available. The temperature maps are generated by combining a straightforward detrending technique with a Digital Elevation Model and a satellite-based land cover classification which also provides the relative forest cover per pixel. The topical aim of the study is to investigate the thermal structure of both manifestations of our ecosystem (pastures and natural vegetation) with special considerations to the ecosystem temperature regulation service by converting natural forest into pasture. The results reveal a clear thermal differentiation over the year, partly triggered by the change of synoptic weather situation but also by land cover effects. Thermal amplitudes are particularly low during the main rainy season when cloudiness and air humidity are high, but markedly pronounced in the relative dry season when daily irradiance and outgoing nocturnal radiation cause distinct differences between the land cover units. Particularly the lower pasture areas gained by slash and burn of the natural forest exhibit the most extreme thermal conditions while the atmosphere inside the mountain forest is slightly cooler due to the regulating effects of the dense vegetation. Thus, clearing the forest clearly reduces the thermal regulation function (regulating ecosystem services) of the ecosystem which might become problematic under future global warming.

Abstract:

Abstract: For the first time in tropical mountain rain forest, arbuscular mycorrhizal fungal richness and community composition was investigated from planted seedlings of Cedrela montana, Heliocarpus americanus, Juglans neotropica and Tabebuia chrysantha in reforestation plots on degraded pastures. A segment of fungal 18S rDNA was sequenced from the mycorrhizas. Sequences were compared with those obtained from mycorrhizas of adult trees of 30 species in the neighboring, pristine tropical mountain rain forest. In total, 193 glomeromycotan sequences were analyzed, 130 of them previously unpublished. Members of Glomeraceae, Acaulosporaceae, Gigasporaceae and Archaeosporales were found in both habitats, with Glomus Group A sequences being by far the most diverse and abundant. Glomus Group A sequence type richness did not appear to differ between the habitats; a large number was observed in both. Glomus Group A sequence type composition, however, was found distinctly different. Seedlings were rarely colonized by fungi of the pristine forest but trapped a number of fungi known from other areas, which were rarely found in the pristine forest.

Abstract:

Distinctive groups of fungi are involved in the diverse mycorrhizal associations of land plants. All previously known mycorrhiza forming Basidiomycota associated with trees, ericads, liverworts or orchids are hosted in Agaricomycetes, Agaricomycotina. Here we demonstrate for the first time that Atractiellomycetes, members of the ?rust? lineage (Pucciniomycotina), are mycobionts of orchids. The mycobionts of 103 terrestrial and epiphytic orchid individuals, sampled in the tropical mountain rain forest of Southern Ecuador, were identified by sequencing the whole ITS1-5.8S-ITS2 region and part of 28S rDNA. Mycorrhizae of 13 orchid individuals were investigated by transmission electron microscopy. Simple septal pores and symplechosomes in the hyphal coils of mycorrhizae from four orchid individuals indicated members of Atractiellomycetes. Molecular phylogeny of sequences from mycobionts of 32 orchid individuals out of 103 samples confirmed Atractiellomycetes and the placement in Pucciniomycotina, previously known to comprise only parasitic and saprophytic fungi. Thus, our finding reveals these fungi, frequently associated to neotropical orchids, as the most basal living basidiomycetes involved in mycorrhizal associations of land plants.

Abstract:

To study vegetation/modern pollen rain relationship a total of 41 pollen traps have been installed for one year on an altitudinal transect between 1800 and 3185 ma.s.l. elevation in the montane forest and páramo vegetation type of the ECSF research area, located between Loja and Zamora in the southeastern Ecuadorian Andes. Results revealed that the altitudinal vegetation gradient of lower montane forest, upper montane forest, subpáramo and páramo is well reflected in the modern pollen rain data. Principal component analysis (PCA) on the pollen rain data indicate that a high number of pollen and spore taxa are characteristic for one vegetation type or reflect the altitudinal distribution of genera and families of modern vegetation. However, a considerable number of pollen and spore taxa not representing modern vegetation types were identified as well. Wind dispersal is supposed to be responsible for differences found between plant and pollen distribution patterns. Characteristic pollen and spore taxa for the lower montane forest are Alchornea, Heliocarpus and Hyeronima; for the upper montane forest Cyathea spp., Elaphoglossum ciliatum and Purdiaea nutans; and for the subpáramo Cyperaceae, Ericaceae, Jamesonia and Valeriana. The position of the modern upper timberline in the research area is reflected in the pollen rain by an increase of subpáramo taxa and a decrease of montane forest taxa.

Abstract:

A lake sediment record from Laguna Campana at 2,488 m a.s.l. in the eastern Ecuadorian Andes allows the reconstruction of local environmental conditions over the past 500 years. A high-resolution multi-proxy approach using pollen, spore, charcoal and XRF analyses provides information about lake genesis, hydrological variations and the development of the surrounding vegetation. Results suggest that Laguna Campana originated from a landslide, which are naturally common and anthropogenically promoted in the study area. Human activities, e.g. deforestation or slash and burn cultivation, impacted the local vegetation development and biodiversity during the recorded period. After a first dense layer of pioneer grasses developed on open soil around the small lake, successional stages of secondary upper mountain rainforest forest mainly composed of Alnus and Weinmannia were observed. The record shows no signs of dense forest regeneration but rather open vegetation with trees and a grassy understory. Especially since ca. A.D. 1980, the proportion of forest in the area was reduced, most probably by fire use for pastures, cultivation and wood extraction. Hydrological variability was derived from differences in minerogenic input and variations in Botryococcus braunii and Sphagnum occurrence. After wettest conditions at the study site, probably triggering the landslide, humid conditions persisted until a time of drier conditions between A.D. 1900 and 1960. A subsequent return to wetter conditions was observed over the last decades. XRF analyses suggest an increase in deposition of atmospherically derived lead since the formation of the lake.

Abstract:

It is commonly presumed that plant respiratory CO2 release increases with increasing temperature. However, we report on very contrasting stem CO2 release (R S)?temperature relationships of trees in a species-rich tropical montane forest of southern Ecuador under dry and wet season conditions. Rates of R S were low and completely uncoupled from the dial temperature regime during the humid season. In contrast, during the dry season, R S was generally higher and temperature sensitivity of R S differed greatly in degree and even in the direction of response, indicating that temperature might not be the only determinant of R S. In order to explain the heterogeneity of R S, we related R S to vapour pressure deficit, wind speed and solar radiation as important abiotic drivers influencing transpiration and photosynthesis. Stepwise multiple regression analyses with these meteorological predictors either were biased by high collinearity of the independent variables or could not enhance the ability to explain the variability of R S. We assume maintenance respiration to dominate under humid conditions unfavourable for energy acquisition of the tree, thus explaining the pronounced uncoupling of R S from atmospheric parameters. In contrast, the drier and hotter climate of the dry season seems to favour R S via enhanced assimilatory substrate delivery and stem respiratory activity as well as elevated xylem sap CO2 imports with increased transpiration. In addition, tree individual differences in the temperature responses of R S may mirror diverging climatic adaptations of co-existing moist forest tree species which have their distribution centre either at higher or lower elevations.

Abstract:

Abstract We investigated controls on the water chemistry of a South Ecuadorian cloud forest catchment which is partly pristine, and partly converted to extensive pasture. From April 2007 to May 2008 water samples were taken weekly to biweekly at nine different subcatchments, and were screened for differences in electric conductivity, pH, anion, as well as element composition. A principal component analysis was conducted to reduce dimensionality of the data set and define major factors explaining variation in the data. Three main factors were isolated by a subset of 10 elements (Ca2?, Ce, Gd, K?, Mg2?, Na?, Nd, Rb, Sr, Y), explaining around 90% of the data variation. Land-use was the major factor controlling and changing water chemistry of the subcatchments. A second factor was associated with the concentration of rare earth elements in water, presumably highlighting other anthropogenic influences such as gravel excavation or road construction. Around 12% of the variation was explained by the third component, which was defined by the occurrence of Rb and K and represents the influence of vegetation dynamics on element accumulation and wash-out. Comparison of base- and fast flow concentrations led to the assumption that a significant portion of soil water from around 30 cm depth contributes to storm flow, as revealed by increased rare earth element concentrations in fast flow samples. Our findings demonstrate the utility of multi-tracer principal component analysis to study tropical headwater streams, and emphasize the need for effective land management in cloud forest catchments.

Abstract:

not available

Abstract:

This paper deals with natural disturbances and their impact on vascular plant enrichment at two climatically contrasting Andean ranges, i.e. the perhumid Cordillera Real in southern Ecuador and the arid Cordillera de Atacama in northern Chile. In the first case, main triggers for an additional input of pioneer species during succession stages initiated by perturbations are landslides, mudflows, and, to a lesser extent, cohort mortality, floods, and wildlife damages. Droughts and wind are stressors, which reduce plant growth but hardly plant diversity, in contrast to enhanced UV radiation with its mutagen effect. Though stress effects are similar in the Atacama, disturbance regimes differ considerably in this dry mountain environment. Here, most perturbations are of small dimension such as nitrogen inputs by feces of Lamoids and burrow activities of tuco-tuco mice, both of them fostering nitrophilous plant communities. Flooding, gelifluction, and other denudation processes such as sheet wash occur too, however, do not charge species enrichment in the dry Andes. Although the perhumid study site represents one of the world’s plant diversity “hotspots” and, by contrast, the arid one a comparatively “coldspot”, pioneer species during successive stages after natural disturbances contribute in a similar percentage to the total plant inventories (appr. 10% of the species numbers). Relatively seen, natural disturbances are most important for species enrichment in the Atacama (200–500 species per 10 000 km2), while most other ecological factors delimit plant survival. Instead, plant life at the Ecuadorian study area benefits from many climatic and edaphic site conditions, and consequently, disturbances are considered only one of many driving forces for its hotspot status (>5000 species per 10 000 km2).

Abstract:

Ecuadorian mountain rainforests are declining dramatically due to deforestation. Exploitation of remaining forests has led to low abundances of native, valuable timber species. Enrichment planting of selected native tree species into forest gaps is a strategy that may increase their abundance and maintain biodiversity. However, the development of successful planting strategies requires knowledge of environmental demands on, and ecological requirements of, native species during their establishment. This knowledge is currently lacking for midand latesuccessional species in Central American forests. Two deciduous, mid-successional (Cedrela montana, Tabebuia chrysantha) and two evergreen, late-successional native tree species (Nectandra membranacea, Podocarpus sprucei) were planted into felling gaps. Photosynthetic performance and growth in height of these species were assessed along light gradients during seedling establishment to test whether species-specific light responses were related to plant successional traits. Both mid-successional species benefited from higher light levels in gaps up to 30% canopy openness60. In larger gaps, C. montana exhibited a significant decline in growth. As expected, growth of the latesuccessional species was only marginally increased at higher light levels. Nevertheless, the photosynthetic apparatus of N. membranacea displayed rapid acclimation to higher light conditions in gaps. Plant response to felling gaps may not always be predicted based on successional status. Our results suggest that the four investigated species may coexist in the same gap by occupying different niches along light gradients. This arrangement may offer an ecological basis to increase the abundance of valuable timber species through enrichment planting in Ecuador mountain rainforests.

Abstract:

Aneura pinguis (Aneuraceae) is a cosmopolitan thalloid liverwort that shows a specific mycorrhiza-like interaction with basidiomycetes. To date, tropical specimens have not been studied in great depth. Samples of A. pinguis were collected from 48 individuals in one plot in South Ecuador and 54 individuals in five European countries. Light and transmission electron microscopy and molecular analyses based on nuclear rDNA coding for the ribosomal large subunit (nucLSU) and from the 5.8s-ITS2 regions were carried out to identify the associated mycobionts and to study their phylogenetic relationships. Microscopic and ultrastructural investigations of the fungal colonisation showed a high congruence between the European and the Ecuadorian sites and confirmed previous results. Tulasnellales are the only mycobionts that could be detected from ultrastructural characters with certainty. Molecular phylogenetic analysis indicated the presence of tulasnelloid fungi from at least 13 distinct clades. The composition of the communities of tulasnelloid fungi in A. pinguis differs between Ecuador and Europe. The diversity of tulasnelloid fungal partners was much higher at the Ecuadorian site.

Abstract:

Tropical regions are currently undergoing remarkable rates of land use change accompanied by altered litter inputs to soil. In vast areas of Southern Ecuador forests are clear cut and converted for use as cattle pastures. Frequently these pasture sites are invaded by bracken fern, when bracken becomes dominant pasture productivity decreases and the sites are abandoned. In the present study implications of invasive bracken on soil biogeochemical properties were investigated. Soil samples (0–5 cm) were taken from an active pasture with Setaria sphacelata as predominant grass and from an abandoned pasture overgrown by bracken. Grass (C4 plant) and bracken (C3 plant) litter, differing in C:N ratio (33 and 77, respectively) and lignin content (Klason-lignin: 18% and 45%, respectively), were incubated in soils of their corresponding sites and vice versa for 28 days at 22 C. Unamended microcosms containing only the respective soil or litter were taken as controls. During incubation the amount of CO2 and its d13C-signature were determined at different time intervals. Additionally, the soil microbial community structure (PLFA-analysis) aswell as the concentrations of KCl-extractable C and N were monitored. The comparison between the control soils of active and abandoned pasture sites showed that the massive displacement of Setaria-grass by bracken after pasture abandonment was characterized by decreased pH values accompanied by decreased amounts of readily available organic carbon and nitrogen, a lower microbial biomass and decreased activity as well as a higher relative abundance of actinomycetes. The d13C-signature of CO2 indicated a preferential mineralization of grass-derived organic carbon in pasture control soils. In soils amended with grass litter the mineralization of soil organic matter was retarded (negative priming effect) and also a preferential utilization of easily available organic substances derived from the grass litter was evident. Compared to the other treatments, the pasture soil amended with grass litter showed an opposite shift in the microbial community structure towards a lower relative abundance of fungi. After addition of bracken litter to the abandoned pasture soil a positive priming effect seemed to be supported by an N limitation at the end of incubation. This was accompanied by an increase in the ratio of Gram-positive to Gram-negative bacterial PLFA marker. The differences in litter quality between grass and bracken are important triggers of changes in soil biogeochemical and soil microbial properties after land use conversion.

Abstract:

The genus Eois (Larentiinae) comprises an important part of a megadiverse assemblage of geometrid moths in the mountain rainforests of southern Ecuador. Owing to the diversity of morphotypes found in this genus, the abundance of many of its component species, and the close relationships with larval food plants in the genus Piper, the genus Eois has been chosen as a target for a more detailed investigation of local species diversity, species delimitations, and ecological segregation. COI barcode sequences (676 bp) were generated from approximately 350 individuals to establish an inventory of DNA barcodes from one study area (Reserva Biológica San Francisco). This inventory will be used to match larvae to known adult samples and will be of vital help to extend the currently very limited knowledge about food plant relationships and host specialization. Analyses of barcoding sequence divergence show that when a conservative morphology-based approach in species delimitation is used a few cases arise were maximum within-species distances exceed minimum betweenspecies distances. However, there is a varying degree of evidence for the presence of cryptic species in all of these critical cases, as gained from analyses of elongation factor 1-alpha sequences, phylogenetic analysis and morphological reexamination. Up to 33 previously unrecognized species could be identified with the help of COI barcodes and morphological evidence in addition to at least 10 entirely new species, thereby increasing the number of Eois morphospecies in that small area of Andean mountain forests from 99 to 142. Notably there are no cases where two or more previously known morphospecies had to be lumped (i.e. there was no cryptic polymorphism). Morphospecies were either confirmed or evidence for cryptic species was found. We acquired elongation factor 1-alpha sequences and extended COI sequences of approximately 100 individuals representing at least 70 Eois species amounting to a combined sequence dataset of ~2200 bp. Maximum parsimony and Bayesian inference of phylogeny have been employed to estimate relationships within Eois. Phylogenetic trees reveal that all included wing-pattern types except for one evolved only once. The exception to this rule occurs in the most basal clade whose species closely resemble those in a clade higher up in the tree. This may represent an ancestral character state or the result of convergent evolution. Additionally it could be determined that species known to feed on Piper are spread over most of the major clades within Eois, indicating that the host plant relationship with Piper is indeed a trait found all over the neotropical members of the genus and not just certain subclades. Within the Larentiinae Eois has traditionally been placed close to the Eupitheciini, but there is presently no support for such a placement in our phylogenetic analyses.

Abstract:

During four months of field surveys at the Reserva Biológica San Francisco in the south Ecuadorian Andes, caterpillars of 59 Geometridae species were collected in a montane rainforest between 1800 and 2800m altitude and reared to adults. The resulting data on host plant affiliations of these species was collated. The preimaginal stages of 58 and adult stages of all 59 species are depicted in colour plates. Observations on morphology and behaviour are briefly described. Five species, documented for the first time in the study area by means of larval collections, had not been previously collected by intensive light-trap surveys. Together with published literature records, life-history data covers 8.6% of the 1271 geometrid species observed so far in the study area. For 50 species these are the first records of their early stages, and for another 7 the data significantly extend known host plant ranges. Most larvae were collected on shrubs or trees, but more unusual host plant affiliations, such as ferns (6 geometrid species) and lichens (3 geometrid species), were also recorded. Thirty-four percent of the caterpillars were infested by wasp or tachinid parasitoids.

Abstract:

Abstract. Available proxy records witnessing palaeoclimate of the tropical Andes are comparably scarce. Major implications of palaeoclimate development in the humid and arid parts of the Andes are briefly summarized. The long-term behaviour of ENSO has general significance for the climatic history of the Andes due to its impact on regional circulation patterns and precipitation regimes, therefore ENSO history derived from non-Andean palaeo-records is highlighted. Methodological constraints of the chronological precision and the palaeoclimatic interpretation of records derived from different natural archives, such as glacier sediments and ice cores, lake sediments and palaeo-wetlands, pollen profiles and tree rings are addressed and complementary results concerning former climatic conditions are discussed in terms of possible implications of former atmospheric circulation patterns and main climatic forcing factors. During the last years, increasing tree-ring information is getting available from the tropical Andes, providing high-resolution climate-sensitive records covering the past centuries for the study of climate variability.

Abstract:

Abstract Mountain pastures dominated by the pasture grass Setaria sphacelata in the Andes of southern Ecuador are heavily infested by southern bracken (Pteridium arachnoideum), a major problem for pasture management. Field observations suggest that bracken might outcompete the grass due to its competitive strength with regard to the absorption of photosynthetically active radiation (PAR). To understand the PAR absorption potential of both species, the main aim of the current paper is to (i) parameterize a radiation scheme of a two-big leaf model by deriving structural (LAI, leaf angle parameter) and optical(leaf albedo, transmittance) plant traits for average individuals from field surveys, (ii) to initialise the properly parameterized radiation scheme with realistic global irradiation conditions of the Rio San Francisco Valley in the Andes of southern Ecuador, and (iii) to compare the PAR absorption capabilities of both species under typical local weather conditions. Field data show that bracken reveals a slightly higher average leaf area index (LAI) and more horizontally oriented leaves in comparison to Setaria. Spectrometer measurements reveal that bracken and Setaria are characterised by a similar average leaf absorptance. Simulations with the average diurnal course of incoming solar radiation (1998-2005) and the mean leaf-sun geometry reveal that PAR absorption is fairly equal for both species. However, the comparison of typical clear and overcast days show that two parameters, (i) the relation of incoming diffuse and direct irradiance, and (ii) the leaf-sun geometry play a major role for PAR absorption in the two-big leaf approach: Under cloudy sky conditions (mainly diffuse irradiance), PAR absorption is slightly higher for Setaria while under clear sky conditions (mainly direct irradiance), the average bracken individual is characterized by a higher PAR absorption potential. (~74 MJ m-2 a-1) . The latter situation which occurs if the maximum daily irradiance exceeds 615 W m-2 is mainly due to the nearly orthogonal incidence of the direct solar beam onto the horizontally oriented frond area which implies a high amount of direct PAR absorption during the noon maximum of direct irradiance. Such situations of solar irradiance favouring a higher PAR absorptance of bracken occur in ~36% of the observation period (1998-2005). By considering the annual course of PAR irradiance in the San Francisco Valley, the clear advantage of bracken on clear days (36% of all days) is completely compensated by the slight but more frequent advantage of Setaria under overcast conditions (64% of all days). This means that neither bracken nor Setaria show a distinct advantage in PAR absorption capability under the current climatic conditions of the study area.

Abstract:

The drivers of spatial throughfall heterogeneity are still not fully understood. At an undisturbed forest site in the Ecuadorian Andes with ca. 2600 mm of annual rainfall we determined the accuracy of throughfall measurements by comparing Hellmann-type funnel gauges with troughs. At the same undisturbed and a managed, selectively-logged forest site we determined spatial variability of throughfall, temporal stability of spatial variability and the controls of spatial throughfall variability using a 4-year dataset in weekly resolution. There were no systematic differences between the collected volumes of funnel gauges and troughs. Based on the statistical distribution of annual throughfall volumes, a high number of 27 funnel-type rainfall collectors were required in the undisturbed forest and 20 in the managed forest to estimate throughfall with an error of 10% and a confidence interval of 95%. Spatial throughfall variability in the studied forests was high, markedly stable during 4 years and similar in six selected rain events suggesting that a stable canopy structure controlled throughfall variability. After mathematically eliminating the canopy influence, no meteorological variable had a significant effect on throughfall variability. We conclude that the high spatial variability of throughfall in the study forest, mainly controlled by a long-term stable canopy structure, contributes to the creation of different ecological niches which are a prerequisite for the enormous biological diversity of the north Andean forests.