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

Abstract:

In tropical agriculture, the vigorously growing Bracken fern causes severe problems by invading pastures and out-competing the common pasture grasses. Due to infestation by that weed, pastures are abandoned after a few years, and as a fatal consequence, the biodi- versity-rich tropical forest is progressively cleared for new grazing areas. Here we present a broad physiological comparison of the two plant species that are the main competitors on the pastures in the tropical Ecuadorian Andes, the planted forage grass Setaria sphacelata and the weed Bracken (Pteridium arachnoideum).With increasing elevation, the competitive power of Bracken increases as shown by satellite data of the study region. Using data obtained from field measurements, the annual biomass production of both plant species, as a measure of their competitive strength, was modeled over an elevational gradient from 1800 to 2800 m. The model shows that with increasing elevation, biomass production of the two species shifts in favor of Bracken which, above 1800 m, is capable of outgrowing the grass. In greenhouse experiments, the effects on plant growth of the presumed key vari- ables of the elevational gradient, temperature and UV radiation, were separately analyzed. Low temperature, as well as UV irradiation, inhibited carbon uptake of the C4-grass more than that of the C3-plant Bracken. The less temperature-sensitive photosynthesis of Bracken and its effective protection from UV radiation contribute to the success of the weed on the highland pastures. In field samples of Bracken but not of Setaria, the content of flavo- noids as UV-scavengers increased with the elevation. Combining modeling with measure- ments in greenhouse and field allowed to explain the invasive growth of a common weed in upland pastures. The performance of Setaria decreases with elevation due to suboptimal photosynthesis at lower temperatures and the inability to adapt its cellular UV screen.

Abstract:

A reliable estimation of Above Ground Biomass (AGB) in Tropical Mountain Forest (TMF) is still complicated, due to fast-changing climate and topographic conditions, which modifies the forest structure within fine scales. The variations in vertical and horizontal forest structure are hardly detectable by small field plots, especially in natural TMF due to the high tree diversity and the inaccessibility of remote areas. Therefore, the present approach used remotely sensed data from a Light Detection and Ranging (LiDAR) sensor in combination with field measurements to estimate AGB accurately for a catchment in the Andes of south-eastern Ecuador. From the LiDAR data, information about horizontal and vertical structure of the TMF could be derived and the vegetation at tree level classified, differentiated between the prevailing forest types (ravine forest, ridge forest and Elfin Forest). Furthermore, topographical variables (Topographic Position Index, TPI; Morphometric Protection Index, MPI) were calculated by means of the high-resolution LiDAR data to analyse the AGB distribution within the catchment. The field measurements included different tree parameters of the species present in the plots, which were used to determine the local mean Wood Density (WD) as well as the specific height-diameter relationship to calculate AGB, applying regional scale modelling at tree level. The results confirmed that field plot measurements alone cannot capture completely the forest structure in TMF but in combination with high resolution LiDAR data, applying a classification at tree level, the AGB amount (Mg ha??1) and its distribution in the entire catchment could be estimated adequately (model accuracy at tree level: R2 > 0.91). It was found that the AGB distribution is strongly related to ridges and depressions (TPI) and to the protection of the site (MPI), because high AGB was also detected at higher elevations (up to 196.6 Mg ha??1, above 2700 m), if the site is situated in depressions (ravine forest) and protected by the surrounding terrain. In general, highest AGB is stored in the protected ravine TMF parts, also at higher elevations, which could only be detected by means of the remote sensed data in high resolution, because most of these areas are inaccessible. Other vegetation units, present in the study catchment (pasture and subpáramo) do not contain large AGB stocks, which underlines the importance of intact natural forest stands.

Abstract:

Bio-economic modelling has become a useful tool for anticipating the outcomes of policies and technologies before their implementation. Advances in mathematical programming have made it possible to build more comprehensive models. In an overview of recent studies about bio-economic models applied to land-use problems in agriculture and forestry,we evaluated howaspects such as uncertainty,multiple objective functions, system dynamics and time have been incorporated into models. We found that single objective models were more frequently applied at the farm level, while multiple objective modelling has been applied to meet concerns at the landscape level. Among the objectives, social aspects are seldom represented in allmodels, when being compared to economic and environmental aspects. The integration of uncertainty is occasionally a topic, while stochastic approaches are more frequently applied than non-stochastic robust methods. Mostmultiple-objectivemodels do not integrate uncertainty or sequential decision making. Static approaches continue to be more recurrent than truly dynamic models. Even though integrating multiple aspects may enhance our understanding of a system; it involves a tradeoff between complexity and robustness of the results obtained. Land-use models have to address this balance between complexity and robustness in order to evolve towards robust multiple-objective spatial optimization as a prerequisite to achieve sustainability goals.

Abstract:

Although fine root traits are crucially important for plants and ecosystems, little is known about the mechanisms driving their variation. According to the theory of the plant economics spectrum, plants have to adopt a consistent strategy for all organs on a one-dimensional axis from slow to fast nutrient acquisition. The different strategies are supposed to be reflected in fine root traits, and to vary with resource availability. This master’s thesis aimed to investigate the variation of tree fine root traits along a topographical gradient in southern Ecuador, and their coordination with aboveground traits, in order to find evidence for a plant economics spectrum. In a tropical montane forest near Loja, fine root systems (diameter < 2 mm) of 179 adult trees were sampled from 18 plots at different slope positions. The steep slopes in this megadiverse ecosystem are characterized by decreasing fertility from the lower to the upper slope, and a high turnover of tree species on small scales along the slopes. The traits root diameter, specific root length (SRL), root tissue density (RTD), root branching intensity (RBI) and nitrogen content (N root ) were measured on each root system. The root traits were tested for being correlated with a topography index, edaphic factors, and aboveground traits. These relationships were analyzed both on the level of plot means and individual trees. Moreover, functional dispersion of the root traits was calculated for each plot and related to the topographical gradient. Pagel’s ? was calculated as an indicator of phylogenetic signal for each root trait. Furthermore, mixed effect models and principal component analyses were calculated in order to better understand the complex relationships between environment, plant traits, and phylogeny. Fine roots tended to be thicker and less intensely branched, contain less nitrogen and have lower SRL with increasing distance from the lower slope. Functional dispersion decreased from lower to upper slope. Especially SRL and N root were closely linked to aboveground traits. Trees with high SRL and N root tended to have softer wood and leaves, higher specific leaf area and higher leaf N and P concentrations. These trends were also apparent when comparing plot means instead of data from tree individuals. This indicates that trees evolved consistent resource economic strategies that manifest in their fine roots, wood, and leaves. Species with a slow, conservative strategy are typical for the upper slopes, whereas acquisitive species assembled at the lower slopes. However, RTD was independent from the topographical gradient and most aboveground traits. SRL, N root and root diameter had strong phylogenetic signals. Rubiaceae and Moraceae were typical families with acquisitive traits growing at the lower slope, whereas the early-diverged Lauraceae occurred predominantly at the upper slope and had very thick roots of the conservative type. These findings provide valuable new insights into patterns of fine root trait variation. They confirm the hypothesis of a plant economics spectrum where root traits are integrated, and demonstrate that tree species in tropical montane forests assemble along topographical gradients according to their resource economics strategies and the associated trait combinations.

Abstract:

Montane ecosystems are known for their high numbers of endemic species, unique climate conditions, and wide variety of ecosystem services such as water supply and carbon storage. Although many ecohydrological and climatic studies of montane environments have been carried out in temperate and boreal regions, few have been done in Neotropical regions. Hence, the objective of this review is to synthesize the existing literature on the main factors (biotic and abiotic) that influence vegetation distribution, functional traits, and ecohydrological processes and feedbacks in tropical montane ecosystems and to identify key knowledge gaps. Most of the literature used includes work conducted in Neotropical montane rainforests, cloud forests, and grass/scrublands (e.g., páramos, punas, and campos de altitude/rupestres). Fog is a major cli- matic attribute in tropical montane habitats. We found that fog regimes (frequency and intensity of fog events) influence both water inputs (i.e., canopy interception and foliar water uptake) and outputs (evapotranspiration) and represent an important driver of local species composition, dominance of plant functional types, and ecological functioning. The stability and conservation of tropical montane ecosystems depends on such ecohydrological fluxes, which are sensitive to increases in air temperature and changing precipitation and fog regimes. Furthermore, to better inform effective conservation and restoration strategies, more work is needed to elucidate how key ecohydrological processes are affected by land use conversion to agriculture and pasture lands, as human activities influence the water budgets in Neotropical montane watersheds not only at regional?scales but also globally. KEYWORDS

Abstract:

Tropical forests harbor diverse ecological communities of plants and animals that are organized in complex interaction networks. The diversity and structure of plant–animal interaction networks may change along elevational gradients and in response to human-induced habitat fragmentation. While previous studies have analyzed the effects of elevation and forest fragmentation on species interaction networks in isolation, to our knowledge no study has investigated whether the effects of forest fragmentation on species interactions may differ along elevational gradients. In this study, we analyzed main and interaction effects of elevation and forest fragmentation on plant–frugivore interaction networks at plant and bird species level. Over a period spanning two years, we recorded plant–frugivore interactions at three elevations (1000, 2000 and 3000 m a.s.l.) and in two habitat types (continuous and fragmented forest) in tropical montane forests in southern Ecuador. We found a consistent effect of elevation on the structure of plant–frugivore networks. We observed a decrease in the number of effective bird partners of plants and, thus, a decline in the redundancy of bird species with increasing elevation. Furthermore, bird specialization on specific plant partners increased towards high elevations. Fragmentation had a relatively weak effect on the interaction networks for both plant and bird species, but resulted in a significant increase in bird specialization in fragmented forests at high elevations. Our results indicate that forest fragmentation may have stronger effects on plant–frugivore interaction networks at high compared to low elevations because bird species richness declined more steeply towards high elevations than plant species richness. We conclude that conservation efforts should prioritize the maintenance of consumer diversity, for instance by maintaining stretches of continuous forest. This applies in particular to species-poor communities, such as those at high elevations, as the ecological processes in these communities seem most sensitive towards forest fragmentation.

Abstract:

Recent studies raise the hypothesis that Na shortage restricts decomposition and affects the carbon cycle in tropical forests. When Na concentrations in soils are low and the stands are far off-coast, they do not receive substantial Na inputs from the atmosphere. Since terrestrial plants have low concentrations of Na, which is not considered as an essential element, the demand of soil fauna may not be covered. Yet, in contrast to animals, little is known on Na demands of phyllosphere microorganisms. This thesis presents results from a study on Na limitation in a montane forest ecosystem in South Ecuador, which is located on the Eastern cordillera of the Andes, in a microcatchment under an undisturbed lower montane rainforest. The study area is characterized by low Na concentrations because of low deposition rates with incident precipitation and by low Na stocks in in the soils and in the organic layer. Sodium fluxes in rainfall, throughfall, stemflow, litter leachate, litterfall and organic layer have been monitored since 1998. Results reveal overall low Na concentrations in the ecosystem fluxes. Higher Na fluxes with incident rainfall than with throughfall suggest that Na is retained in the canopy. Therefore, this study aims at testing the hypothesis that Na is retained in the canopy because of Na limitation of microorganisms in phyllosphere. To explore the role of the phyllosphere in Na retention, I sampled leaves covered by phyllosphere microorganisms and leaves without phyllosphere cover from 12 tree species belonging to 7 plant families frequently occurring in the study area. The fresh leaves were sprayed with a NaCl solution containing 1 mg L-1 Na, corresponding to the Na concentration in incident rainfall in the study area during La Niña events. Comparison with a control treatment excluded effects by abiotic Na fixation on the surface of the leaves. The results show that increasing phyllosphere cover leads to a significantly enhanced Na retention, which is much higher on understory tree leaves than on leaves of the upper canopy. Leaching of K, Ca and Mg was higher with increasing degree of phyllosphere cover, which can be attributed to increasing element exchange between foliage and phyllosphere with leaf age. These results suggest that Na availability possibly plays a regulating role in the study ecosystem which might even grow in importance if Na deposition from the atmosphere continues to decrease or stabilizes at the current low level.

Abstract:

Seasonally dry forests in the neotropics are heavily threatened by a combination of human disturbances and climate change; however, the severity of these threats is seldom contrasted. This study aims to quantify and compare the effects of deforestation and climate change on the natural spatial ranges of 17 characteristic tree species of southern Ecuador dry deciduous forests, which are heavily fragmented and support high levels of endemism as part of the Tumbesian ecoregion. We used 660 plant records to generate species distribution models and land-cover data to project species ranges for two time frames: a simulated deforestation scenario from 2008 to 2014 with native forest to anthropogenic land-use conversion, and an extreme climate change scenario (CCSM4.0, RCP 8.5) for 2050, which assumed zero change from human activities. To assess both potential threats, we compared the estimated annual rates of species loss (i.e., range shifts) affecting each species. Deforestation loss for all species averaged approximately 71 km2/year, while potential climate-attributed loss was almost 21 km2/year. Moreover, annual area loss rates due to deforestation were significantly higher than those attributed to climate-change (P < 0.01). However, projections into the future scenario show evidence of diverging displacement patterns, indicating the potential formation of novel ecosystems, which is consistent with other species assemblage predictions as result of climate change. Furthermore, we provide recommendations for management and conservation, prioritizing the most threatened species such as Albizia multiflora, Ceiba trichistandra, and Cochlospermum vitifolium.

Abstract:

Soils of Páramo ecosystems regulate the water supply to many Andean populations. In spite of being a necessary input to distributed hydrological models, regionalized soil water retention data from these areas are currently not available. The investigated catchment of the Quinuas River has a size of about 90 km2 and comprises parts of the Cajas National Park in southern Ecuador. It is dominated by soils with high organic carbon contents, which display characteristics of volcanic influence. Besides providing spatial predictions of soil water retention at the catchment scale, the study presents a detailed methodological insight to model setup and validation of the underlying machine learning approach with random forest. The developed models performed well predicting volumetric water contents between 0.55 and 0.9 cm3 cm? 3. Among the predictors derived from a digital elevation model and a Landsat image, altitude and several vegetation indices provided the most information content. The regionalized maps show particularly low water retention values in the lower Quinuas valley, which go along with high prediction uncertainties. Due to the small size of the dataset, mineral soils could not be separated from organic soils, leading to a high prediction uncertainty in the lower part of the valley, where the soils are influenced by anthropogenic land use.

Abstract:

Forest site classification adapted to the respective site conditions is one prerequisite for sustainable silviculture. This work aims to initiate the forest site classification for pine plantations in the southern Andean region of Ecuador. Forest productivity, estimated by the dominant height of 20-year-old trees (DH20), was related to data from climate, topography, and soil using 23 plots installed in pine plantations in the province of Loja. Forest site productivity was classified as: low (class C: 13.4 m), middle (class B: 16.6 m), and high (Class A: 22.3 m). Strong determinants to differentiate the forest site classes were: the short to medium term available Ca and K stocks (organic layer + mineral soil standardized to a depth of 60 cm), soil acidity, the C:N ratio, clay and sand content, forest floor thickness, altitude, and slope. The lowest forest productivity (Class C) is mainly associated with the lowest short to medium term available K and Ca stocks. Whereas, in site classes with the highest forest productivity, pines could benefit from a more active microbial community releasing N and P, since the soil pH was about 1 unit less acidic. This is supported by the lowest forest floor thickness and the narrowest C:N ratio.

Abstract:

Tropical ecosystems offer a unique setting for understanding ecohydrological processes, but to date, such investigations have been limited. The purpose of this paper is to highlight the impor- tance of studying these processes—specifically, how they are being affected by the transforma- tive changes taking place in the tropics—and to offer an agenda for future research. At present, the ongoing loss of native ecosystems is largely due to agricultural expansion, but parallel pro- cesses of afforestation are also taking place, leading to shifts in ecohydrological fluxes. Similarly, shifts in water availability due to climate change will affect both water and carbon fluxes in trop- ical ecosystems. A number of methods exist that can help us better understand how changes in land use and climate affect ecohydrological processes; these include stable isotopes, remote sens- ing, and process?based models. Still, our knowledge of the underlying physical mechanisms, espe- cially those that determine the effects of scale on ecosystem processes, remains incomplete.We assert that development of a knowledge base concerning the effects of transformative change on ecological, hydrological, and biogeochemical processes at different spatio?temporal scales is an urgent need for tropical regions and should serve as a compass for emerging ecohydrologists. To reach this goal, we advocate a research agenda that expands the number and diversity of eco- systems targeted for ecohydrological investigations and connects researchers across the tropics. We believe that the use of big data and open source software—already an important integrative tool/skill for the young ecohydrologist—will be key in expanding research capabilities.

Abstract:

Global changes in nutrient deposition rates are likely to have profound effects on plant communities, particularly in the nutrient-limited systems of the tropics. We studied the effects of increased nutrient availability on the seedlings of six tree species in montane forests of southern Ecuador in situ. After five years of continued N, P, or N+P addition, naturally grown seedlings of each of the two most common species at each elevation (1000, 2000, and 3000 m asl) were harvested for analyses of leaf morphology, nutrient content, herbivory, and tissue biomass allocation. Most species showed increased foliar N and P concentrations after addition of each respective element. Leaf tissue N:P ratios of >20 in the control plants of all species suggest that P is more growth-limiting in these forests than N. Leaf morphological responses to nutrient addition were species and nutrient specific, with some species (Hedyosmum purparescens, Graffenrieda emarginata) exhibiting increased specific leaf area (SLA), and others (Graffenrieda harlingii) increased leaf area ratios (LAR). Pouteria torta (1000 m) had lower SLA and LAR after P addition. Increased herbivory was only evident in G. emarginata (after N and N+P addition). Only the species from 3000 m asl modified biomass allocation after nutrient addition. In general, N and N+P addition more strongly affected the species studied at the upper elevations, whereas P addition had a similar range of effects on the species at all elevations. We conclude that the responses of the studied tropical montane forest tree seedlings to chronic N and P addition are highly species-specific and that successful adaptation to increased nutrient availability will depend on species-specific morphological and physiological plasticity.

Abstract:

To assess the susceptibility of the base metal budget of a remote tropical montane forest in Ecuador to environmental change, we determined the extent of biological control of base metal fluxes and explored the impact of atmospheric inputs and precipitation considered as potential drivers of ecosystem change on the base metal fluxes. We quantified all major base metal fluxes in a ca. 9.1 ha forested catchment from 1998 to 2013. Mean (±s.d.) annual flux to the soil via throughfall+ stemflow+litterfall was 13800±1500 mg m-2 Ca, 19000±1510 mg m-2 K, 4690±619 mg m-2 Mg and 846±592 mg m-2 Na of which 22±6%, 45±16%, 39±10% and 84±33%, respectively, were leached to below the organic layer. The mineral soil retained 79-94% of this Ca, K and Mg, while Na was released. Weathering rates estimated with three different approaches ranged from not detected (ND) to 504 mg m-2 yr-1 Ca, ND-1769 mg m-2 yr-1 K, 287-597 mg m-2 yr-1 Mg and 403-540 mg m-2 yr-1 Na. The size of mainly biologically controlled aboveground fluxes of Ca, K and Mg was 1-2 orders of magnitude larger than that of mainly geochemically controlled fluxes (sorption to soil and weathering). The elemental catchment budgets (total deposition-streamflow) were positive for Ca (574±893 mg m-2) and K (1330±773 mg m-2), negative for Na (-370±1300 mg m-2) and neutral for Mg (1.89±304 mg m-2). Our results demonstrate that biological processes controlled element retention for Ca, K and Mg in the biological part of the ecosystem. This was different for Na, which was mainly released by weathering from the study catchment, while the biological part of the ecosystem was Na-poor. The deposition of base metals was the strongest driver of their budgets suggesting that the base metal cycling of the study ecosystem is susceptible to changing deposition.

Abstract:

In 201 3, the “Platform for Biodiversity and Ecosystem Monitoring and Research in South Ecuador” (www.TropicalMountainForest.org) was launched as a knowledge transfer program in the biodiversity hotspot of the southern Ecuadorian Andes, jointly funded by the German Research Foundation (DFG) and Ecuadorian non-university partners. One of the overall aims of the transdisciplinary program is to design science-directed recommendations for an ecologically sustainable, economically profitable and socially compatible use of the mainly rural land. The second major goal of the program is the development of functional indicators that are crucial for the monitoring of impacts of environmental change on the ecosystem and its functions. They encompass abiotic, abiotic-biotic and biotic-biotic interrelations, and are sensitive - though to different extent - to subtle changes in the environment. Therefore, it is not only the interaction per se, which has to be examined. In addition to that the quantification of the response to certain environmental stressors is needed. Representing the fundament of ecosystem functioning, biodiversity as such or certain functional taxa can be monitored for an assessment of the ecosystem’s state. Important further criteria for the selection of an indicator are general applicability, easiness of handling and stability against pitfalls. This book “Landscape Restoration, Sustainable Use and Cross-scale Monitoring of Biodiversity and Ecosystem Functions: A Science-directed Approach for South Ecuador” presents in its first part a compilation of sustainable land use concepts that have been proven for application in the Provinces Loja and Zamora Chinchipe and beyond, given comparable environmental conditions. The second part describes functional indicators as well as their development, monitoring and application. Both parts start with introductory chapters on the major aims of the respective transdisciplinary program, followed by contributions showing how land use concepts can be used to achieve sustainable management and ecosystem services, as well as how functional indicators can be used to assess and monitor the stability of biodiversity and ecosystem functions. It should be stressed that this book has not the aim to present only a scientific summary of the developed systems. Instead, it targets on stakeholders as our non-university partners and beyond which are in charge of environmental planning and ecosystem function surveillance in Ecuador. In the manner of a technical handbook, it gives a comprehensible introduction to the land use option or the indicator, followed by hints how to apply, implement and assess the developed systems. The book is and was complementing our three pillars of capacity building which also includes stakeholder workshops on the developed land use options and indicators, and demonstration plots in the field. With this book the authors highly acknowledge the generous funding of the research by the German Science Foundation (DFG) and the logistic, administrative and practical support by the foundation Naturaleza y Cultura Internacional (Loja and Del Mar). Such research requires also fruitful collaboration with local academic institutions, the Universidad Tecnica Particular de Loja, the Universidad Nacional de Loja, the Universidad de Cuenca, the Universidad de Azuay, and the local weather service INAMHI. These partnerships were a great experience in capacity building on both sides, as evidenced by a number of academic degrees obtained and by numerous joint publications. The authors are also grateful for the support of our nonuniversity research partners beyond NCI, namely ETAPA EP (Empresa Pública Municipal de Telecomunicaciones, Agua potable, lcantarillado y Saneamiento de Cuenca- Ecuador), the Gobierno Municipal de Zamora and the regional water fund FORAGUA (Fondo Regional del Agua). Further, sincere thanks are owed to the Ecuadorian Ministry of the Environment (MAE) for permission to conduct research in South Ecuador. The Editors

Abstract:

Economic approaches based on the probabilistic framework were applied to support land use management in Ecuador. Compensations to prevent further land conversion resulted lower when a concave utility function was used. Diversification applied to risky conventional farming showed that sustainable options are suited for portfolios if correlation between returns is kept low; in every case at least two options constituted the optimal combinations. Thus, despite limitations of bio-economic models, they constitute a reliable tool for normative orientations at the farm level.

Abstract:

Recent studies raise the hypothesis that Na shortage restricts decomposition and affects the carbon cycle in tropical forests. When Na concentrations in soils are low and the stands are far off-coast, they do not receive substantial Na inputs from the atmosphere. Since terrestrial plants have low concentrations of Na, which is not considered as an essential element, the demand of soil fauna may not be covered. Yet, in contrast to animals, little is known of Na demands of fungi and phyllosphere microorganisms. We present results from a study on Na limitation in a montane forest ecosystem in South Ecuador, which is located on the eastern cordillera of the Andes. We tested the hypotheses that (1) the study area is characterized by low Na concentrations because of low deposition rates with incident precipitation (wind directions mainly from the Amazonian Basin), (2) decomposition processes are limited by fauna and fungal Na restrictions and (3) Na is retained in the canopy because of Na limitation of microorganisms in phyllosphere. Since 1998, we measure Na fluxes in rainfall, throughfall, stemflow, litter leachate, litterfall and organic layer in a microcatchment under an undisturbed lower montane rainforest. Results reveal comparatively low Na concentrations in the ecosystem and similar Na concentrations in throughfall and stemflow. Since Na fluxes are lower with throughfall than with incident rainfall, we conclude that Na is retained in the canopy. To explore the role of the phyllosphere in Na retention we sampled leaves covered by phyllosphere microorganisms and leaves without phyllosphere cover from several tree species, which were sprayed with a NaCl solution containing 0.5 mg L-1 Na, corresponding to the Na concentration in incident rainfall in our study area. Additionally, responses of litter decomposition to Na additions and the involved interaction of soil fungi and fauna were tested in a litterbag experiment at two sites (1000 and 2000 m a.s.l.). Results revealed enhanced decomposition rates following Na additions, though only in the presence of soil fauna. These results might have future ecosystem implications, since our time series showed that total Na deposition decreased within the past 15 years from ca. 40 kg ha-1 a-1 to 10 kg ha-1 a-1, suggesting a potential role of Na in regulating ecosystem processes.

Abstract:

Trait response-effects are critical to forecast community structure and biomass production in highly diverse tropical forests. Ecological theory and few observation studies indicate that trees with acquisitive functional traits would respond more strongly to higher resource availability than those with conservative traits. We assessed how long-term tree growth in experimental nutrient addition plots (N, P and N+P) varied as a function of morphological traits, tree size and species identity. We also evaluated how trait-based responses affected stand scale biomass production considering the community structure. We found that tree growth depended on interactions between functional traits and the type or combination of nutrients added. Common species with acquisitive functional traits responded more strongly to nutrient addition, mainly to N+P. Phosphorous enhanced the growth rates of species with acquisitive and conservative traits, had mostly positive effects on common species and neutral or negative effects in rare species. Moreover, trees receiving N+P grew faster irrespective of their initial size relative to control or to other treatment plots. Finally, species responses were highly idiosyncratic suggesting that community processes including competition and niche dimensionality may be altered under increased resource availability. We found no statistically significant effects of nutrient additions on aboveground biomass productivity because acquisitive species had a limited potential to increase their biomass, possibly due to their generally lower wood density. In contrast, P addition increased the growth rates of species characterized by more conservative resource strategies (with higher wood density) that were poorly represented in the plant community. We provide the first long-term experimental evidence that trait-based responses, community structure, and community processes modulate the effects of increased nutrient availability on biomass productivity in a tropical forest.

Abstract:

The relative importance of catchment's water provenance and flow paths varies in space and time, complicating the conceptualization of the rainfall-runoff responses. We assessed the temporal dynamics in source areas, flow paths, and age by End Member Mixing Analysis (EMMA), hydrograph separation, and Inverse Transit Time Proxies (ITTPs) estimation within a headwater catchment in the Ecuadorian Andes. Twenty-two solutes, stable isotopes, pH, and electrical conductivity from a stream and 12 potential sources were analyzed. Four end-members were required to satisfactorily represent the hydrological system, i.e., rainfall, spring water, and water from the bottom layers of Histosols and Andosols. Water from Histosols in and near the riparian zone was the highest source contributor to runoff throughout the year (39% for the drier season, 45% for the wetter season), highlighting the importance of the water that is stored in the riparian zone. Spring water contributions to streamflow tripled during the drier season, as evidenced by geochemical signatures that are consistent with deeper flow paths rather than shallow interflow through Andosols. Rainfall exhibited low seasonal variation in this contribution. Hydrograph separation revealed that 94% and 84% is preevent water in the drier and wetter seasons, respectively. From low-flow to high-flow conditions, all the sources increased their contribution except spring water. The relative age of stream water decreased during wetter periods, when the contributing area of the riparian zone expands. The multimethod and multitracer approach enabled to closely study the interchanging importance of flow processes and water source dynamics from an interannual perspective.

Abstract:

Deforestation and land use change have led to a strong reduction of tropical forest cover during the last decades. Climate change will amplify the pressure to the remaining refuges in the next years. In addition, tropical regions are facing increasing atmospheric inputs of nutrients, which will have unknown consequences for the structure and functioning of these systems, no matter if they are within protected areas or not. Even remote areas are expected to receive rising amounts of nutrients. The effects of higher rates of atmospheric nutrient deposition on the biological diversity and ecosystem functioning of tropical ecosystems are poorly understood and our knowledge of nutrient fluxes and nutrient limitation in tropical forest ecosystems is still limited. Yet, it will be of paramount importance to know the effects of increased nutrient availability to conserve these ecosystems with their biological and functional diversity. During the last years, research efforts have more and more focused on the understanding of the role of nutrients in tropical ecosystems and several coordinated projects have been established that study the effects of experimental nutrient addition. This Research Topic combines results from experiments and from observational studies with the aim to review and conclude on our current knowledge on the role of additional nutrients in ecosystems.

Abstract:

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

Abstract:

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

Abstract:

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

Abstract:

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

Abstract:

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

Abstract:

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

Abstract:

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

Abstract:

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