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

Abstract:

Tropical forests are well known for their exceptional species richness ? high diversity of plant species constitute the basis for an equivalently rich fauna. An astonishing variety of plant life strategies has evolved, manifesting itself also in different compositions of life history traits in trees. This thesis investigates the role of tree life history traits (growth, mortality and recruitment) on different processes structuring species-rich forests. Our study system is a montane rainforest located in the Tropical Andes hotspot of biodiversity in southern Ecuador. Here, we find a mosaic of steep ridges and deeply incised valleys, covered with predominantly broadleaf forest. Forest structure and species composition differ considerably depending on altitude and topographic position. The forest cover is frequently interrupted by scars of landslides, which constitute an important type of natural disturbance in this ecosystem. We utilize ecological models as tools to gain deeper insights into key processes driving the maintenance of tree species richness and affecting forest recovery after landslides. The first part of this thesis concerns the question of species coexistence. We develop a theoretical model to analyze how different trade-offs between life history traits (tree growth, seed dispersal, tree mortality) affect tree species coexistence. We find that the considered trade-offs alone are not sufficient to explain long-term species coexistence. Additional ?stabilizing? mechanisms seem to be indispensable to facilitate coexistence in species-rich forests. Such mechanisms could result from biotic interactions, that alter the relation between inter- and intra-specific competition depending on (local) species abundances (e.g. density-dependent mortality). Other possible coexistence mechanisms likely to be relevant to our particular study system are driven by external, abiotic factors like a complex topography resulting in locally differing habitat types (each supporting a different set of species), or the character of a prevailing disturbance regime (e.g. shallow landslides). In the second part of the thesis, we investigate the growth dynamics of the ridge forest in our study system. To this end, we utilize the process-based forest growth model FORMIND. We show that after calibration, the model successfully reproduces forest dynamics on different levels of complexity (e.g. basal area and stem size distribution). We then use this forest model to investigate the influence of landslide disturbances on forest dynamics both on the local scale of a single landslide and on the landscape scale. On landslide sites, changes in environmental conditions might lead to changes in different tree life history traits. We analyze scenarios with changes in different traits (tree recruitment, tree growth, tree mortality) and find that while tree biomass can recover within the first hundred years after a landslide, the time until forest structure and species composition is restored is considerably longer (approximately 200 years). Changes in different traits result in differing spatial distributions of tree biomass: reduced tree growth leads to a more homogeneous distribution of biomass, whereas reduced recruitment and increased mortality yield a more heterogeneous biomass distribution (?patchy? vegetation). On the landscape level, overall forest biomass is substantially reduced by landslides (8 - I 14%), compared to only 2 -3% of the area marked by visible traces of landslides. Thus this particular type of disturbance considerably influences the total forest carbon balance. In a complementary investigation we study abiotic and biotic factors that potentially trigger landslide occurrence in our study system. For this, we develop an extension of a standard physically-based model of slope stability. We find that due to the predominantly shallow tree roots, some of the observed landslides might be triggered by the vegetation itself. This thesis demonstrates that ecological models are useful tools to gain deeper insights into important processes shaping forest communities. They can be applied for theoretical questions such as the question of species coexistence, as well as for more applied, management related questions like predicting forest recovery after disturbances.

Abstract:

The tropical mountain rain forests in Southern Ecuador belong to one of the five global hot spots of biodiversity. At the same time it is one of the most endangered ecosystems in the world due to the continuous and accelerated deforestation over the last 50 years. The aim of this study was to contribute to a sustainable use of natural resources as well as to ask for sustainable strategies of land use in the tropical mountain rain forest, analyzing the use and the management of natural resources (forest, soil and water) by the Saraguros and Mestizos in the watershed of Tambo Blanco. The study area (115 Km²) is located in the Eastern Andes between 1,680 - 3,400 m a.s.l., representing an example of a new colonized region in the 1960s, which is part of the protected forest area Corazón de Oro and the Biosphere Reserve Podocarpus - El Cóndor. The investigation focused on the following topics: land use change since the beginning of the agricultural colonization, the use and the management of natural resources, the practices and strategies for the conservation of natural resources by the local people, as well as the evaluation of the use of natural resources forest, soil, and water under the terms of sustainability. The qualitative and quantitative land use change was analyzed for the years 1976, 1987 and 2001, through the use of remote sensing and geographical information system (GIS). Use and management of natural resources by the local people was evaluated on the basis of further geographical methods like observations, interviews (100 half standardized interviews, 20 expert interviews) and land use mapping. The results of land use change showed, that the tropical mountain rain forest had been reduced about 22 % (1,695.597 ha) during 25 years, representing an average of 67.82 ha/year, mainly due to the transformation of natural forests into pasture land. Páramo areas over 3,000 m a.s.l. remained almost unchanged. That indicates that the land use change was concentrated in the tropical mountain forest between 1,600 and 2, 800 m a.s.l. Overall, between 1976 and 2001, the rate of deforestation (0.99 %) was very high. How-ever, the first period between 1976 and 1987 showed a higher deforestation rate (1,16 %) than the last period between 1987 and 2001 (0,86 %). The main reasons for a decreasing deforestation rate seemed to be the establishment of livestock farming as well as the concomitant reduction of forestry, as a result of a deficiency of precious wood and a price decline of timber. Despite a diminishing timber industry over the last years, the establishment of livestock farming as the new principal economic activity has lead to a continuing deforestation of tropical mountain forests. The concentration in only one economical activity, like livestock farming does not resolve the problems of poverty in the investigation area. In addition, the local people depend mainly on one single economic activity and on the prices dictated by external markets. For SUMMARY 186 these reasons there is a continuous loss of traditional practices such as the cultivation in chacras und huertas for the subsistence of the family and, not least, a loss of biodiversity in the tropical mountain forests of Southern Ecuador. Despite these negative scenarios, it must be recognized, that the local people have also development practices and strategies for the conservation of natural resources throughout the accumulated experience of many decades. This includes, for example, reforestation, planting of ?living fences?, conservation of particular forest areas, introduction of silvopastoral systems, weed control with the machete instead of burning, sowing of fast growing grasses, rotation of pastures, use of organic fertilizer, etc. For a sustainable development within the study area, the solution of ecological and economical problems like poverty, unemployment and lack of education will be required. Therefore the cooperation of governmental and non-governmental organizations, research institutions and local people is very important. Despite the problems for sustainable development in tropical mountain forests, practical measures to overcome the problems can be identified, including reforestation with native tree species, the implementation of appropriate grazing systems like silvopastoral systems, and the conservation of water resources, at least in the higher parts of the watershed of Tambo Blanco. An economical sustainability could be achieved by the diversification of employment and income through the establishment of local trades and business, ecotourism and educational tourism, etc. Not least, the responsibility of the local people to protect the tropical mountain forest and their resources, including the development of environmental principles, the setting of limits concerning the use of natural resources and an implementation of environmental education, can contribute to the development of a social sustainability. Institutional sustainability can be achieved by resolving institutional conflicts, the utilization of the potential synergy of all organizations and the collaborations for sustainable development in Southern Ecuador as a common goal. For a successful and sustainable management within the Podocarpus - El Cóndor biosphere reserve, the integration of local knowledge and practical experience represent the main trigger, which form a basis for the sustainable use of natural resources in the tropical mountain forests.

Abstract:

We reconstructed the palaeoenvironmental conditions of the last ca. 8000 years in the Tres Lagunas region of the Quimsacocha volcanic basin (ca. 3800 m a.s.l.) in the southwestern Ecuadorian Andes. By means of a pollen and charcoal record, we analysed vegetation, fire, and climate history of this area, which is sensitive to climatic changes of both the Pacific as well as of the eastern Andes and Amazon region. Sediment deposits, pronounced increase of pollen and charcoal concentrations, and pollen taxa reflect warmer and drier conditions in the early to mid-Holocene (~8000 to 3900 cal B.P.). During the late Holocene (2250 to -57 cal B.P.), 5 warm and cold-phases occurred at Quimsacocha. The most prominent cold phase possibly corresponds to the globally recognized Little Ice-Age (LIA; ~600 to 100 cal B.P.). The cold phase signal at Quimsacocha was characterized by a higher abundance of Poaceae, Isoëtes and Gentianella, which favour cold and moist conditions. Frequent charcoal particles can be recorded since the early to mid-Holocene (~7600 B.P.). The high Andean tree species Polylepis underwent several phases of degradation and re-establishment in the basin, which can indicate the use of fire by pre-Columbian settlers to enhance the growth of preferred herb species. The Tres Lagunas record suggests that human populations have been influencing the environment around Quimsacocha since the last ca. 8,000 years.

Abstract:

The new structure of the planned research platform is visualized. For the first time scientists report about the income of small farms as well as about their plant and land use which were analyzed by thorough interviews. Members of the Research Unit show how the forest responds to elevated nitrogen deposition and display nitrogen, nitrous oxide and nitric oxide fluxes. They also explain climate-growth-relationships in trees, and describe the factors which are affecting the spatial distribution of trees. The data warehouse manager introduces how to filter and aggregate tabular values. Our partner NCI reports about a mayor breakthrough in the conservation of people and biodiversity in Perú. EDIT partners analyzed the distribution of ants and partners from the UTPL introduce a study that will be conducted to sample geo-information in South Ecuador.

Abstract:

The montane and premontane rainforests of southern Ecuador constitute a hotspot of biodiversity (cf. Brehm et al. 2008; Barthlott et al. 2007, Neill 2007). The use of plant resources from these forest areas is a fundamental part of the portfolio of livelihood activities of the local population. Increasing human activity however results in biodiversity loss. The extension of pastures and fields, logging, mining and the construction of roads represent the main threats to biodiversity in southern Ecuador. In order to develop conservation strategies it is of utmost importance to understand the plant and forest-use patterns of the inhabitants of this region. In this way, it will be possible to develop alternatives that consider local claims while conserving biodiversity (cf. Pohle et al. 2010). In this study ethnoecological and agrogeographical research methods have been used to make a qualitative analysis of the ethnospecific plant knowledge and plant use of the three main ethnic groups of southern Ecuador, namely the Shuar, the Saraguros and the Mestizos. This is followed by a discussion of the feasibility in the study sites of four so-called instruments for biodiversity conservation: agroforestry, ecotourism, payments for environmental services, and bioprospecting. The resulting ethnobotanical inventory includes 644 useful species and 16 main use categories. Edible and medicinal plants are the most important use categories. Ten percent of the identified species (64) has not been mentioned in the Encyclopaedia of the useful plants of Ecuador (de la Torre et al. 2008) so far. Herbs and trees represent the most common life forms used by all studied ethnic groups. The Shuar are traditional forest dwellers and have a comprehensive knowledge of plants: 316 different plant species with a total of 493 uses have been recorded. They are traditionally engaged in a number of livelihood activities that include fishing, hunting, and the gathering of wild plants. They get more than 40% of the plant species they use from the forests. In addition, they cultivate plant species which cannot be sufficiently (e.g. edible plants) or promptly (e.g. medicinal plants, ritual and mythical plants, fish poisons) extracted from the forest. The high number and variety of uses (ranging from edible fruits to shampoos and insecticides) reflect their wide plant knowledge. Similar to other Amazonian cultures, the traditional subsistence system of the Shuar is based on a combination of home gardens, slash and burn cultivation in forest gardens and the extraction of resources from the forest. In recent times the Shuar have entered the market economy through the small-scale production of cash crops, cattle ranching, and logging. At present population levels, the traditional home and forest gardens represent sustainable production systems and places of great agrobiodiversity (Pohle et al. 2010; Pohle & Gerique 2008; 2006). Increased production of cash crops could however result in habitat destruction. In addition, cattle ranching and logging have a negative impact. Pasture land competes with forest for land and requires the clearing of large tracts of forest. Due to the logging commercial timber, species such as Terminalia amazonia, Platymiscium pinnatum or Cedrelinga cateniformes have been over-exploited. The Shuar have apparently over-exploited game species as well, a factor that may have consequences in plant diversity: The zoochory or dispersion of seeds and other diaspores by wild animals could have been negatively affected. The possible over-use of certain non-timber forest products such as palm hearts remains unclear. Without being ?ecologically noble savages? (cf. Alvard 1993) the Shuar are effective partners for biodiversity conservation. Their land use system can be considered sustainable (Pohle et al. 2010; Pohle & Gerique 2008; 2006; Rudel et al. 2002). The inventory of the Saraguros of El Tibio and El Cristal comprises 230 plant species with a total of 310 uses; among the Mestizo of Los Guabos, Sabanilla, El Retorno, and La Fragancia 312 useful species with a total of 409 uses has been recorded. The ethnobotanical knowledge of the Saraguro and the Mestizo settlers is generally similar. They make little use of forest plant resources; less than 10% of the species used by the Saraguros and 5% of the species used by the Mestizos are forest plants, mostly timber species. The forest is considered a reserve for new pasture and maize production. In contrast to the Shuar, who mainly use wild species collected in the forest, the Saraguros and the Mestizos make an extended use of wild species that grow in disturbed sites and pastures. Most relevant are cultivated species, which represent half of the plants used by both ethnic groups. Cultivated plants are used in cattle ranching (e.g. fodder species, shade trees, living fences), and secure and diversify food supplies and plant remedies. Both groups make an extended use of cultivated ornamental plants. In recent times some families have introduced new ornamental species and sell them outside the communities. The ethnobotanical survey suggests that ongoing acculturation processes result in the loss of plant knowledge. Their integration into the market economy has probably replaced traditional self-made products with goods acquired in market places, which results in a loss of plant knowledge among younger generations (Reyes García et al. 2005; Benz et al. 2000; Putsche 2000). Most Saraguros and Mestizos have arrived in the area of study over the past six decades; the first settlers were poor landless farmers searching for land. The removal of trees for grazing and agricultural lands was a basic requirement to prove possession of land in order to get property titles from the Ecuadorian State (Barsky 1988). As a result, large areas of montane forest were cleared by burning. In this way, both ethnic groups have transformed most of the pristine vegetation of their communities into pastures. The construction of the road between Loja and Zamora during the 1960s attracted more settlers; they worked as day laborers or, if they had enough capital, bought existing fincas (Pohle & Gerique 2006). The road also allowed the exploitation of timber, mainly of the romerillo species (Podocarpus oleifolius and Prumnopitys montana). While the basic food supply is guaranteed by cultivation in fields and home gardens, cattle raising is market oriented. Today it represents the main land use system among Saraguros and Mestizos and fulfills multiple objectives: the production of beef and dairy products provides households with a regular income, it awards a prestigious social status, and represents a way of accumulating wealth. However, the forest is basically considered to be a reserve for new land for pastures and agriculture. The Saraguros and the Mestizos jeopardize in this way the sustainability of their economic systems; the forest, which is its own resource base, is being reduced. On the basis of these findings, the implementation of the above mentioned instruments for biodiversity conservation is discussed. In the case of the Shuar, ways must be found to conserve their traditional ecological knowledge during their inevitable transition to modernity and the market economy. It is necessary to foster additional sources of income that improve human well being and the conservation of biodiversity, and that make non-traditional, non-sustainable practices such as cattle ranching unnecessary. Without sustainable income alternatives, market forces and the demographic pressure would lead to an intensification of logging, large scale agriculture, and mining activities. Community-based ecotourism appears, in the short term, to be the most promising sustainable source of alternative income, followed by the implementation of agroforestry systems in the medium term. Other options such as payments for environmental services (e.g. REDD programs) and bioprospecting ventures appear less attractive, as they are hostage to political interests, bad image and unclear legislation. In the case of the Saraguros and Mestizos, the actual land use system based on cattle ranching turns out to be incompatible with the conservation of forest resources and long term household prosperity. Its significance in local economies should thus be reduced through diversification. An agroforestry system that includes reforestation, restoration and connection of forest patches, and sustainable selective logging could be implemented in the medium term (cf. Günter et al. 2009; Knoke et al. 2009a; 2009b; Stimm et al. 2008; Weber et al. 2008; Aguirre et al. 2006; Cabrera et al. 2006). In the short term, improved pasture management (including leguminous trees and living fences with useful species), and the small-scale production of niche products in home gardens could be alternatives to cattle ranching (Pohle et al. 2010). Market surveys should be conducted to determine the niche products, and economic safety nets that secure the introduction and viability of alternative sustainable land use activities need to be put in place. Payments for environmental services (e.g. payments for watershed protection or the Ecuadorian Socio Bosque Program) are an example of a way of generating the seed money for such projects. A network of long-distance trails could represent another way of generating alternative income in the region through ecotourism. Finally, to reduce the high scepticism towards conservation, improved environmental education and a readjustment of the borders of disputed protective forest areas must be considered. The realignment needs to take into consideration the demands of long-term inhabitants to gain credence among the local population.

Abstract:

In this study, the Mean Transit Time and Mixing Model Analysis methods are combined to unravel the runoff generation process of the San Francisco River basin (73.5 km2) situated on the Amazonian side of the Cordillera Real in the southernmost Andes of Ecuador. The montane basin is covered with cloud forest, sub-páramo, pasture and ferns. Nested sampling was applied for the collection of streamwater samples and discharge measurements in the main tributaries and outlet of the basin, and for the collection of soil and rock water samples. Weekly to biweekly water grab samples were taken at all stations in the period April 2007–November 2008. Hydrometric data, Mean Transit Time and Mixing Model Analysis allowed preliminary evaluation of the processes controlling the runoff in the San Francisco River basin. Results suggest that flow during dry conditions mainly consists of lateral flow through the C-horizon and cracks in the top weathered bedrock layer, and that all subcatchments have an important contribution of this deep water to runoff, no matter whether pristine or deforested. During normal to low precipitation intensities, when antecedent soil moisture conditions favour water infiltration, vertical flow paths to deeper soil horizons with subsequent lateral subsurface flow contribute most to streamflow. Under wet conditions in forested catchments, streamflow is controlled by near surface lateral flow through the organic horizon. Exceptionally, saturation excess overland flow occurs. By absence of the litter layer in pasture, streamflow under wet conditions originates from the A horizon, and overland flow. Copyright © 2011 John Wiley & Sons, Ltd.

Abstract:

Research on biodiversity, its relation to ecosystem functioning and services, and the assessment of the impacts of environmental change on biodiversity needs an interdisciplinary perspective. This implies a great diversity of data and data formats gathered mostly in short- to mid-term collaborative research projects. It has been common practice that projects develop specific data management and communication solutions. We compare solutions of two major German collaborative research programs in functional biodiversity research to derive functional commonalities. This in-depth analysis follows five categories of the data life cycle: (i) data acquisition, (ii) metadata management, (iii) database, (iv) exploration, analysis and visualization, and (v) data curation and preservation. The results show that even though both systems were developed completely independently, they reveal comparable overall features and a similar state of implementation. Major focus areas lie in the implementation of comparable metadata schemas and their importance for storage and access strategies for tabular data on the value level. Basic analysis tools and similar management functions are considered. Intensive communication with the users and the orientation of ongoing developments based on user requirements is also important. Both systems are different mostly in specific details which, however, do not influence the overall comparable performance. It should be also emphasized that the same functionality is achieved with completely different software. The choice of software is based on the evaluation of available technologies. Thereby it might be influenced by individual experiences of the developers, but is mainly determined by the data diversity, which forces the usage of flexible technologies to develop adaptable systems. It is concluded that overall features for project databases of collaborative research projects must be supplemented by sophisticated data description, storage, and analysis structures to serve the requirements of integrative functional biodiversity research.

Abstract:

Areas with high landslide activity and diversity were encountered in the tropical Andes of Southern Ecuador under contrasting, semi-arid to perhumid climatic conditions. The objective of this study was to determine and compare geomorphic process rates of shallow landslides along this remarkable humidity gradient and subject to different types of human-made and natural environmental changes. Geomorphic work, geomorphic power and landslide mobilization rate (LMR) were therefore calculated for shallow landslides in two study areas with two separate geological or land use-related subareas each. While landslide ages were known in the perhumid Reserva Biológica San Francisco (RBSF) area, only an approximation of the frequency of critical landslide-triggering rainfall events was available for the semi-arid Masamanaca area. Landslide volumes were estimated by volume–area scaling. Generalized additive models (GAMs) were used as landslide susceptibility models in order to analyze the relative importance of topography, and to downscale LMR values to a fine spatial resolution. LMR in the perhumid RBSF area ranged from ˜2 mm yr-1 in the natural part of this area with tropical mountain rainforests to ˜5 mmyr-1 in the human-influenced part. The semi-arid Masamanaca area, though subject to greater estimation uncertainties, displayed LMR on the order of ˜0.4 to 4 mm yr-1 for shallow landslides. The results provide a basis for the spatially differentiated assessment of landscape evolution and degradation in an area with a close relation between landslide activity, natural vegetation succession and human land use.

Abstract:

Die tropischen Regenwälder gehören zu den artenreichsten Lebensräumen der Erde (MITTERMEIER et al. 1999). Insbesondere geodiverse Lebensräume mit ihrer hohen Vielfalt an unterschiedlichen Umweltbedingungen, wie Gebirge und Regionen mit ausgeprägten klimatischen Gradienten, stellen Zentren hoher biologischer Vielfalt dar. So ist es nicht verwunderlich, dass der Übergangsbereich zwischen den tropischen Anden und der Amazonas region in Ecuador zu einem der weltweit fünf „megadiversen hot spots“ der Pflanzenvielfalt gezählt wird. Es handelt sich demnach um Lebensräume mit Diversitätsmaxima von mehr als 5.000 Gefäßpflanzenarten pro 10.000 km2 Fläche (Karte 1; MUTKE & BARTHLOTT 2005, BARTHLOTT et al. 2005). Die gesamten tropischen Anden beherbergen dabei ungefähr ein Sechstel aller bekannten Pflanzen auf weniger als 1 % der weltweiten Landfläche (MITTERMEIER et al. 1997). Auch das relativ kleine Land Ecuador verfügt mit seiner außerordentlichen Vielfalt an Habitaten mit ausgeprägten Höhenund Klimagradienten über eine enorme biologische Diversität. So werden beispielsweise von JØRGENSEN & LEÓN-YÁNEZ (1999) für das Land 15.901 Gefäßpflanzenarten aufgelistet. ULLOA ULLOA & NEILL (2005) ergänzen die Flora Ecuadors auf nunmehr 17.058 Gefäßpflanzenarten, was die Vielfalt von Deutschland (2.682), dessen Staatsgebiet um ca. 25 % größer ist, um mehr als das Sechsfache übertrifft (BREHM et al. 2008). Auf einem einzigen Baum Amazoniens können durchaus so viele Orchideen leben, wie in Mitteleuropa vorkommen (MUTKE & BARTHLOTT 2008).

Abstract:

The cheiridiid subfamily Pycnocheiridiinae is recorded for the first time from south America, Leptocheiridium gen. n. and its type species pfeiferae sp. n. are described and illustrated. The new genus shares with Pycnocheiridium Beier, 1964 (type genus of the Pycnocheiridiinae Beier, 1964) the same morphology of walking legs, eight trichobothria on the fixed chelal finger, only two on the movable finger, and the presence of strongly clavate vestitural setae. Leptocheiridium gen. n. is well characterized by the shape of its slender pedipalps, the presence of three sub-equal setae in the rallum, the presence of five setae on the cheliceral hand, the morphology of the female galea, and the presence of a well-developed transverse furrow on the carapace.

Abstract:

The spatial heterogeneity of tropical forest epiphytes has rarely been quantified in terms of biomass. In particular, the effect of topographic variation on epiphyte biomass is poorly known, although forests on ridges and ravines can differ drastically in stature and exposure. In an Ecuadorian lower montane forest we quantified epiphytic biomass along two gradients: (1) the twig-branch-trunk trajectory, and (2) the ridge-ravine gradient. Twenty-one trees were sampled in each of three forest types (ridge, slope, ravine positions). Their epiphytic biomass was extrapolated to stand level based on basal area?epiphyte load relationships, with tree basal areas taken from six plots of 400 m 2 each per forest type. Our results document the successional addition and partial replacement of lichens by bryophytes, angiosperms and finally dead organic matter along the twig-branch-trunk trajectory. Despite having the highest tree basal area, total epiphytic biomass (mean ± SD) of ravine forest was significantly lower (2.6 ± 0.7 Mg half 1) than in mid-slope forest (6.3 ± 1.1 Mg half 1) and ridge forest (4.4 ± 1.6 Mg half 1), whereas maximum bryophyte water storage capacity was significantly higher. We attribute this pattern to differences in forest dynamics, stand structure and microclimate. Although our study could not differentiate between direct effects of slope position (nutrient availability, mesoclimate) and indirect effects (stand structure and dynamics), it provides evidence that fine-scale topography needs to be taken into account when extrapolating epiphytic biomass and related matter fluxes from stand-level data to the regional scale.

Abstract:

Microbial oxidation in aerobic soils is the primary biotic sink for atmospheric methane (CH4), a powerful greenhouse gas. Although tropical forest soils are estimated to globally account for about 28% of annual soil CH4 consumption (6.2 Tg CH4 year−1), limited data are available on CH4 exchange from tropical montane forests. We present the results of an extensive study on CH4 exchange from tropical montane forest soils along an elevation gradient (1,000, 2,000, 3,000 m) at different topographic positions (lower slope, mid-slope, ridge position) in southern Ecuador. All soils were net atmospheric CH4 sinks, with decreasing annual uptake rates from 5.9 kg CH4?C ha−1 year−1 at 1,000 m to 0.6 kg CH4?C ha−1 year−1 at 3,000 m. Topography had no effect on soil atmospheric CH4 uptake. We detected some unexpected factors controlling net methane fluxes: positive correlations between CH4 uptake rates, mineral nitrogen content of the mineral soil and with CO2 emissions indicated that the largest CH4 uptake corresponded with favorable conditions for microbial activity. Furthermore, we found indications that CH4 uptake was N limited instead of inhibited by NH4 +. Finally, we showed that in contrast to temperate regions, substantial high affinity methane oxidation occurred in the thick organic layers which can influence the CH4 budget of these tropical montane forest soils. Inclusion of elevation as a co-variable will improve regional estimates of methane exchange in these tropical montane forests.

Abstract:

Tropical forests are important sources of the greenhouse gas nitrous oxide (N2O) and of nitric oxide (NO), a precursor of ozone. In tropical montane forests nitrogen limitation is common which affects both soil N2O and NO fluxes and forest productivity. Here we present evidence that forest productivity and N-oxide (N2O + NO) fluxes are linked through N availability along elevation and topographic gradients in tropical montane forests. We measured N-oxide fluxes, several indices of N availability, and forest productivity along an elevation gradient from 1000 m to 3000 m and along topographic gradients. Organic layer thickness of the soils increased and N availability decreased with increasing elevation and along the topographic gradient from the lower slope position to the ridges. Annual N2O fluxes ranged from -0.53 µg(N)m-2h-1 to 14.54 µg(N)m-2h-1 while NO fluxes ranged from -0.02 µg(N)m-2h-1 to 1.13 µg(N)m-2h-1. Both N-oxide fluxes and forest productivity increased with increasing N availability and showed close positive correlations with indices of N availability (C/N ratio and  15N signature of litterfall). We interpret the close correlations of N-oxide fluxes with total litterfall and tree basal area increment as evidence that N availability links N-oxide fluxes and forest productivity. This opens the possibility to include forest productivity as co-variable in predictions of N-oxide fluxes in nitrogen limited tropical montane forests. Especially increment of tree basal area was a promising proxy to predict soil N-oxide fluxes in these N limited ecosystems, possibly because it better reflects long-term forest productivity than total litterfall.

Abstract:

High geomorphic process rates often coincide with the sensitivity of (tropical) mountain eco-systems towards both man-made and naturally controlled environmental changes. Especially the pastured tertiary sediments of the semiarid western Andean slope in Southern Ecuador are characterized by a higher occurrence of gravitational mass movements, reaching the point where the landscape is about to change into "badlands". Based on the analysis of the landslide inventory of a representative study area near Masanamaca the present work dealt with the reasons for these increased geomorphic process rates. The study area stretches over 10 km² and is built up by tertiary sediments in the west and by metamorphic rock in the east. A se-cond aim was the comparison with the study area Reserva Biológica San Francisco (RBSF) on the perhumid, metamorphic slope of the Andes because of major differences regarding precipitation, land use and types of movements. Both study areas are located within a distance of about 35 km. First of all 900 landslides in the study area Masanamaca were mapped and classified with respect to type of movement, material, activity and causing factors. Five different major types of movement were found (438 translational and 25 rotational slides, 63 flow ~, 162 complex ~, 156 composite ~ and 56 fall movements). The slope angle and discontinuities in the bed-rock formed the main preparatory factors which predisposed the slope to failure. In this re-spect the lithology exerted a special influence as well as the biggest landslide density was observed in the tertiary sediments (conglomerate and sand-/siltstone). Precipitation represent-ed the most common triggering factor, a fact which was closely related to the predominant occuerrenc of shallow movements (slides, flows and some complex movements) in the study area which, as widely acknowledged, are mostly rainfall-induced. Especially the initation of large-scale and deep-seated movements such as composite landslides must have required an array of triggering factors. They might also represent an advanced stage of ongoing surface lowering activity which could have had its origin in a small slide scar. The calculation of the denudation rate caused by shallow sliding demanded in the first place the estimation of the displaced landslide volume for both study areas. This was achieved by using area-volume scaling. Secondly, for the study area Masanamaca it was necessary to es-timate the time needed for the regeneration of the observed shallow landslide population. For this purpose thresholds proposed in the literature were used to assess roughly the frequency of landslide triggering rain events in the study area. The literature review in combination with the analysis of the precipitation in the study area resulted in an estimated time span between 10 to 100 years, which corresponded to an annual denudation rate between 0.5 to 5 mm. By con-trast, the analysis of time-lapse airborne imagery for the study area RBSF for six different years made estimations of recurrence intervals unnecessary. For a 38-year period (1962-2000) a denudation rate of 2 mm/y caused by naturally induced landslides and one of 12 mm/y caused by man-made triggered landslides were calculated. All landslides of the study area RBSF were classified as shallow movements. In the study area Masanamaca however much more types of movements were identified. Nevertheless a great number of them were disregarded in the calculation of the denudation rate as neither volume nor recurrence time could be estimated for them. Since these unconsidered movements were both large-scale and deep-seated, it can be assumed that their consideration would have led to a denudation rate potentially higher than the naturally constituted one of the perhumid Andean slope. Presented results can be the basis of further investigations which might focus on the analysis of susceptibility towards shallow landsliding and associated hazards. For this purpose a more suitable denudation rate for the study area Masanamaca would be preferable. This could be achieved by implementing empircal or physical modeling. ²denudation rate = displaced volume/(3-D area of the study area * time)

Abstract:

Soil-vegetation-atmosphere transfer (SVAT) is to be predicted for 2050/2100 for a study area in the southern Ecuadorian Andes. SVAT models require information on land use/ land cover (LUC) as lower boundary conditions. Since the study area suffers from high deforestation rates, LUC cannot be assumed as staying constant with time. A spatially explicit land use/land cover change (LUCC) model is therefore needed for future SVAT prediction. The numbers of approaches of LUCC modelling are numerous. Difficulties are due to complex interactions of social and biophysical drivers of change. In this study a model of LUCC was built using information of past changes derived by remotely sensed data. Special focus was on forest development patterns. A training period of 14 years between 1987 and 2001 was chosen. Two LUC classifications were accomplished to Landsat data of the start and end date of this period. A change detection of the training period provided the basis for predictive LUCC modelling. Potential drivers for LUCC were applied to the model as GIS layers. The modelling procedure consisted of a combination of Markov chain analysis (MCA) for quantitative modelling and multi-layer perceptron (MLP) for revealing potential locations of change. A multi-objective land allocation (MOLA) served as final integration step. 14 LUC transitions were considered in the modelling procedure. Unconsidered LUC classes were assumed to stay constant in the future. The model results were maps of LUC for 2006, 2010 and afterwards for every 10 years up to 2100. An internal validation was performed with the training data. The results of the prediction were validated by comparing the model output of 2006 to an ASTER LUC classification of the same time. The validation methodology comprised crisp and fuzzy map comparison using Kappa statistics. The study area featured a deforestation of 13.61% in the training period. The model was able to explain deforestation in the training period 51% better than just by chance. The location of predicted deforestation reached a better than chance agreement of 30%. Predicted quantities of deforestation were 59% conforming with the reference. The validation of the prediction indicated the difficulty of modelling human impact on the ecosystem. Prospects and limitations of the model were identified with suggestions for future research tasks. The results of this study are assumed to present a good groundwork for future SVAT models.

Abstract:

Caterpillar communities were studied on 16 shrub species from the family Asteraceae and the genus Piper (Piperaceae) in the Andean montane rainforest zone of southern Ecuador. The applied sampling methodology was evaluated and found well suited for sampling of caterpillars, especially with focus on resampling. During standardized sampling, a total of 18890 specimens were collected in 11 field surveys between August 2007 and June 2009. Overall, samples were dominated by gregarious early instars and egg clutches of Altinote dicaeus albofasciata (Nymphalidae) on Erato polymnioides (Asteraceae). Those and all other such groups and egg clutches were downweighted for analyses to their cubic root to balance against their overrepresentation in the data set. Trophic associations of caterpillars were confirmed by feeding trials. A substantial fraction of more than 22% of the encountered caterpillars (and up to 80% on individual shrub species) was found not to be trophically linked to the living biomass of the shrubs themselves (“non-herbivores”), but rather feed on dead leaves and epiphylls. Abundance of nonherbivores differed strongly between the two studied plant families, but was very similar on different shrub species within these families. Abundance of herbivorous caterpillars, to the contrary, differed hardly between plant families, but varied strongly between individual plant species. Herbivores were almost entirely comprised of ectophagous folivores, while florivores (2.3%) and semi-endophagous folivores (leaf rollers and tiers; 6.0%) were unexpectedly rare. Absolute species richness of herbivorous caterpillars was high, with a total of 191 Lepidoptera species on the studied 16 shrub species, but varied up to 40fold between individual plant species. Rarefied species numbers were more similar among plant species, but still showed a 15fold difference between the most species rich and most species poor community. Communities on Piper species were characterized by low effective species numbers (measured as exponential Shannon entropy) and high dominance of one or two species of the Geometridae genus Eois. E. polymnioides featured a similar structure dominated by A. dicaeus albofasciata. Communities on the other two Asteraceae (Ageratina dendroides and Baccharis latifolia), to the contrary, were found to have high effective species numbers and low dominance. In conclusion, while Piper species and E. polymnioides feature caterpillar communities defined by small, predictable sets of core herbivores, these defining sets do not exist for the other two of the studied Asteraceae species. Communities on Piper were also more specialized, with 62.8% of the caterpillar species considered monophagous at plant species level, than on Asteraceae with only 11.6% monophagous species. The observed diversity patterns point mainly to shaping by (chemical) plant-herbivore-defense, while geographic range and local abundance of host plants appear to have only limited and varying influence on the associated caterpillar communities.

Abstract:

The genus Eois comprises an important part of megadiverse assemblages of geometrid moths in mountain rainforests of southern Ecuador. In this study we report: (i) on the construction of a DNA barcode library of Eois for identification purposes; and (ii) the exploration of species diversity through species delimitation by pair-wise distance thresholds. COI barcode sequences were generated from 408 individuals (at least 105 species) collected on a narrow geographic scale (∼40 km2) in the Reserva Biol´ogica San Francisco. Analyses of barcode sequence divergence showed that species delimitations based solely on external morphology result in broad overlap of intra- and interspecific distances. Species delimitation at a 2% pair-wise distance threshold reveals a clear barcoding gap. Fifty-two previously unrecognized species were identified, 31 of which could only be distinguished by an integrative taxonomy approach. Twelve additional putative species could only be recognized by threshold-based delimitation. Most splits resulted in two or three newly perceived cryptic taxa. The present study increased the number of Eois species recorded from that small area of Andean mountain forest from 102 to 154 (morphology- plus integrative taxonomy-based) or even 166 (sequence-based), leaving the species accumulation curve still far from reaching an asymptote. Notably, in no case did two or more previously distinguished morphospecies have to be lumped. This barcode inventory can be used to match larvae to known adult samples without rearing, and will therefore be of vital help to extend the currently limited knowledge about food plant relationships and host specialization.

Abstract:

We analyzed the stocks of Ca, Mg, P, and S in tree rings of Cedrela montana Moritz ex Turcz in order to evaluate the dynamics of element input to a lower montane rain forest in South Ecuador. Samples were taken by a Pressler drill from the living tree (n=5). Afterwards tree rings were separated and digested with concentrated HNO3 under pressure (Heinrichs et al.,1986). Concentrations of Ca and Mg were determined by atomic absorption spectroscopy (AAS), concentrations of P and S by inductively coupled plasma optical emission spectrometry (ICP-OES), respectively. Mean element concentrations in tree rings between 1957 and 2005 were 2.2 g kg-1 for Ca, 1.1 g kg-1 for P and S and 0.4 g kg-1 for Mg. Radial distribution of element concentrations was heterogeneous with exception of the tree rings close to the phloem, where concentrations were generally higher. The pattern of annual radial increment showed significant growth peaks related to strong La Niña events. Also concentrations of P and S peaked during the La Niña events of 1989, 1996, and 2000. For Ca and Mg a similar effect was observed with a time shift of one year. Highest Ca peaks during the monitored period were associated with the 1974 La Niña event, which was also the strongest event on the record. We conclude that tree rings are a suitable tool for recording element inputs of Ca, Mg, P, and S at lower montane rain forests of South Ecuador. Furthermore we found element inputs and growth signals linked to the ENSO cycle.

Abstract:

Catchment-scale runoff generation involves a complex interaction of physical and chemical processes operating over a wide distribution of spatial and temporal scales. Understanding runoff generation is challenged by this inherent complexity ? the more uncertain step of predicting the hydrologic response of catchments is that much more challenging. Many different hypotheses have been implemented in hydrological models to capture runoff generation processes and provide hydrologic predictions. These concepts have been developed based on extended field observations. Here we propose inferring water flux understanding and catchment exploring through the application of a variety of available hydrological models as a mechanism to build upon and extend models that have been developed to capture particular hydrological processes. We view this ensemble modeling strategy as particularly appropriate in ungauged catchments. The study is carried out in a tropical montane rainforest catchment in Southern Ecuador. The catchment is 75 km2 and is covered by forest in the south, while the northern slopes have been partly deforested for grazing. Annual rainfall is highly variable, reaching up to 5700 mm per year in the upper parts of the catchment. To explore the dominating runoff processes, an ensemble of 6 hydrological models with different structures applied over different levels of both spatial and temporal detail was developed. The ensemble includes spatially lumped (HBV-light), semi-distributed (HEC-HMS, CHIMP, SWAT, LASCAM) and a fully distributed model (HBV-N-D). The hydro-statistical toolkit WETSPRO was used to characterize simulated and observed hydrographs. Estimated baseflow indices, flow minima and maxima, flow duration curves and cumulative errors were generated and compared among the ensemble of models. This process facilitated the exploration of processes controlling runoff generation, enabled an evaluation of the applicability of the screened models to tropical montane rainforests, and provided the capacity to evaluate and explain where different models failed.

Abstract:

The understanding of the hydrological functioning of a tropical ecosystem allows to evaluate the consequences of a changed land use. On the east-facing slope of the Andes in Ecuador between 1900 and 2150 m a.s.l. I studied the above- and belowground driving variables of the water budget. The objectives were to determine the elements of the water budget experimentally and with an optimized model and to elucidate the hydraulically relevant processes along five 20 m-long transects in three 8-13 ha-large microcatchments under montane rain forest. Water fluxes were weekly measured between April 1998 and April 2001, the mean annual evapotranspiration was calculated with a budget approach. For the canopy, I determined the water storage capacity and assessed the influence of the vegetation density and epiphyte coverage on interception and canopy evaporation of the precipitation. The vegetation density was approximated by the leaf area index [LAI] and the fraction of the precipitation falling through gaps of the canopy. In addition, I modeled throughfall and stemflow by adapting the analytical canopy model of Gash. In the soil, I determined the saturated hydraulic conductivity and the water contents. To calculate the reaction of surface flow on precipitation events and to identify the soil processes controlling the surface flow, I compared a ?black box? (NAMOD) with a ?semi-empirical? (TOPMODEL) model approach. The mean water storage capacity of the dry leaves is 1.91±1.94 mm and that of the trunks 0.041±0.02 mm. The LAI ranges from 5.2 to 9.3. Epiphytes - mainly mosses - cover up to 80% of the trunk and branch surfaces. The fraction of precipitation falling through gaps of the canopy correlates significantly with the interception loss (r = -0.77, n = 40). During dry periods the mosses and lichens tend to decrease the water storage capacity of the trunks. The saturated hydraulic conductivity decreases drastically at the border between organic layer and mineral soil where it was highly variable. The high stone content of, on average, 40Vol.% has a substantial effect of the flow regime. Based on the results of the precipitation-surface flow modeling the hydraulically effective soil layer can be separated into two water reservoirs (organic layer and mineral soil). The water flow in the soil occurres rapidly in lateral direction in the organic layer and/or much slower, mainly vertically in the deeper mineral soil layers. Water flow in the latter soil layers during strong rain events is little likely, because the organic layer is rapidly saturated favoring interflow. The weekly surface flow measurements result in an overestimation of the annual water output from the catchments because high flow events were overrepresented. The mean annual surface flow in the three catchments, calculated on the basis of daily modeled flow rates, ranges between 27 and 46% of the precipitation. The annual evaporation, calculated on the basis of daily surface flow rates, ranges between 1281 and 1889 mm, i.e. 54-73% of the precipitation. My results demonstrate that rapid lateral water flow in the organic layer of the soil dominates the flow regime. The destruction of the forest and removal of the organic layer would result in soil erosion and increased intensity of high-flow events.

Abstract:

Tropical mountain regions are characterized by strong spatial climate gradients which together with the limited amount of data and knowledge of the underlying processes hinder the management of the water resources. Especially for regional-scale prediction it is important to identify the dominant factors controlling the rainfall?runoff response and link those to known spatial patterns of climate, soils, and vegetation. This study analyzes the rainfall?runoff relation of 13 intensively monitored micro-catchments in the Andes of southern Ecuador. The results of this study show that streamflow in the southern cordillera of the Ecuadorian Andes, above 2500 m a.s.l., primarily consists of subsurface flow. The yearly amount of streamflow is controlled by the annual rainfall depth, whereas the temporal distribution is mainly governed by the lateral saturated hydraulic conductivity, the soil water retention and the antecedent soil moisture content. Anthropogenic effects were found insignificant, with the exception in one of the studied micro-catchment. Effect of land use changes in most of the micro-catchments did not reflect in the shape of the flow duration curve because either the spatial extent of human impact was small and/or the overall basin slope was less than 20%.