Jörg Bendix

Gradients in a Tropical Mountain Ecosystem of Ecuador

Part I Introduction 1 The Ecosystem (Reserva Biologica San Francisco) E. Beck, F. Makeschin, F. Haubrich, M. Richter, J. Bendix, C. Valerezo 2 Mountain rain forests in southern Ecuador as a hotspot of biodiversity - Limited knowledge and diverging patterns G. Brehm, J. Homeier, K. Fiedler, I. Kottke, J. Illig, N.M. Noske, F. Werner, S-W. Breckle 3 The people settled around Podocarpus National Park P. Pohle 4 Ecuador suffers the highest deforestation rate in South America R. Mosandl, S. Gunter, B. Stimm, M. Weber 5 Methodological challenges of a megadiverse ecosystem G. Brehm, K. Fiedler, Ch. Hauser, H. Dalitz Part II Gradients in ecosystem analysis 6 Why investigating gradients in ecosystem analysis K. Fiedler, E. Beck 7 The investigated gradients E. Beck, R. Mosandl, M. Richter, I. Kottke Part III The altitudinal gradient Part III.1 Gradual changes along the altitudinal gradient 8 Climate J. Bendix, R. Rollenbeck, M. Richter, P. Fabian, P. Emck 9 Soils along the altitudinal transect and in catchments W. Wilcke, S. Yasin, A Schmitt, C. Valarezo, W. Zech 10 Flora: Composition and function 10.1 Potential vegetation and floristic composition of Andean forests in South Ecuador, with a focus on the RBSF J. Homeier, F. A. Werner, S. R. Gradstein, S -W. Breckle, M. Richter 10.2 Past vegetation and fire dynamics H. Niemann & H. Behling 10.3 Forest structure along an altitudinal gradient in southern Ecuador A. Paulsch, D. Piechowski, K. Muller-Hohenstein 10.4 Vegetation structures and ecological features of the upper timberline ecotone M. Richter, K.-H. Diertl, Th. Peters, R. W. Bussman 10.5 Mycorrhizal state and new and special features of mycorrhizae of trees, ericads, orchids, ferns andliverworts I. Kottke, A. Beck, I. Haug, S. Setaro, V. Jeske, J.P. Suarez, L. Paxmino, M. Preussing, M, Nebel, F. Oberwinkler 11 Fauna: Composition and function 11.1 Bird species distribution along an altitudinal gradient in southern Ecuador and its functional relationships with vegetation structure D. Paulsch and K. Muller-Hohenstein 11.2 Seed dispersal by birds, bats and wind F. Matt, K. Almeida, A. Arguero, C. Reudenbach 11.3 Variation of diversity patterns across moth families along a tropical elevational gradient K. Fiedler, G. Brehm, N. Hilt, D. Sussenbach, and C.L. Hauser 11.4 Soil fauna M. Maraun, J. Illig , D. Sandman,V. Krashevskaya, R.A. Norton, S. Scheu Part III.2 Processes along and within the gradient 12 Water relations W. Wilcke, S. Yasin, K. Fleischbein, R. Goller, J. Boy, J. Knuth, C. Valarezo, W. Zech 13 Nutrient status and fluxes at the field and catchment scale W. Wilcke, S.Yasin, K. Fleischbein, R. Goller, J. Boy, J. Knuth, C. Valarezo, W. Zech 14 Biotic soil activities S. Iost, F. Makeschin, M. Abiy, F. Haubrich 15 Elevational changes in stand structure and biomass allocation of tropical mountain forests in relation to microclimate and soil chemistry G. Moser, M. Roderstein, N. Soethe, D. Hertel, C. Leuschner 16 Stand structure, transpiration responses in trees and vines and stand transpiration of different forest types within the mountain rainforest M. Kuppers, T. Motzer,D. Schmitt., C. Ohlemacher, R. Zimmermann, V. Horna, B.I.L. Kuppers, T. Mette 17 Plant growth along the altitudinal gradient-role of plant nutritional status, fine root activity, and soil properties N. Soethe, W. Wilcke, J. Homeier, J. Lehmann, C. Engels Part III.3 Gradient heterogeneities Part III.3.A Spatial heterogeneities 18 Spatial

A satellite-based climatology of fog and low-level stratus in Germany and adjacent areas

A 10-year fog climatology of Germany and adjacent areas, based on NOAA-Advanced Very High-Resolution Radiometer (AVHRR) data, is presented. Maximum fog frequency is obtained for the Lake Constance area; minimum fog occurrence, accounting for basins and river valleys, is located in the Lower Rhine area. This is a transition zone between coastal advection fog and the more continental radiation fog of the lower mountain range. Fog persistence is estimated by a comparison of night and day maps. Using the bispectral approach of Nakajima and Nakajima [J. Atmos. Sci. 52, (1995) 4043], the potential of weather satellite data for climatologies of fogs optical and microphysical properties is examined. Maps of fog optical depth, effective radius and liquid water path (LWP) are computed from well-illuminated noon images and the resulting data set is statistically evaluated. Typical features of advection fog are obtained for the coastal areas of the North and Baltic Seas, while the fog of the pre-Alpine basins reveals characteristics of continental radiation fog. The results are in general accordance with field observations of various sources.

Precipitation dynamics in Ecuador and northern Peru during the 1991/92 El Niño : a remote sensing perspective

The formation, dynamics and spatial distribution of heavy precipitation during the 1991/92 El Nino in Ecuador and northern Peru were examined by means of Meteosat-3 imagery, NOAA-AVHRR-based multichannel sea surface temperatures (MCSST) and additional meteorological observations. The Convective and Stratiform Technique (CST) was used for rain retrieval by means of Meteosat IR data and a cross-correlation approach was applied to Meteosat image sequences to derive cloud motion winds (CMW) which are essential for the analysis of circulation patterns leading to severe precipitation. From an analysis of 45 days with severe precipitation it is proven that three mechanisms were responsible for the formation of heavy rains. Each mechanism reveals a specific localized impact. (1) The most frequent mechanism (frequency of ∼61%) represents an extended land-sea breeze system. During such weather conditions, predominantly locally confined precipitation patterns occured. Areas affected by the sea wind front during the day were the coastal plains up to the 1000 m contour line on the western Andean slope. Local maxima in the frequency of cloudiness leading to precipitation could be found at isolated peaks of a lower coastal cordillera. At night the highest frequency of precipitation was found over the warm water surface of the Gulf of Guayaquil, mainly due to its coastal shape which significantly favours convergence of the nocturnal land breeze. (2) Convection, initiated in the coastal plain and on the western Andean slopes during the afternoon, was significantly intensified by an entrainment of remainders of cirrus shields from the Amazon basin. These cloud fragments spilled over the Andes with well-developed trades in the mid/upper troposphere which blew in the opposite direction to the daily sea/up-slope breeze. The spill over points were characterized by areas of deep convection on the western Andean slopes and were frequently valley axes perpendicular to the mountain chain as well as the Andean depression in southern Ecuador. (3) During the main El Nino phase (March-April), heavy and persistent precipitation was extended over wide areas of the coastal plain showing neither a distinct diurnal cycle nor preferential areas. Deep convection was frequently organized in mesoscale convective complexes (MCC) and was spatially correlated with MCSST > 27 . The extensive instability of the troposphere during these weather conditions was marked by convective cloud streets and an intensification of the meridional Hadley circulation off the coast of southern Ecuador and Peru.

Land-cover classification in the Andes of southern Ecuador using Landsat ETM+ data as a basis for SVAT modelling

A land‐cover classification is needed to deduce surface boundary conditions for a soil–vegetation–atmosphere transfer (SVAT) scheme that is operated by a geoecological research unit working in the Andes of southern Ecuador. Landsat Enhanced Thematic Mapper Plus (ETM+) data are used to classify distinct vegetation types in the tropical mountain forest. Besides a hard classification, a soft classification technique is applied. Dempster–Shafer evidence theory is used to analyse the quality of the spectral training sites and a modified linear spectral unmixing technique is selected to produce abundancies of the spectral endmembers. The hard classification provides very good results, with a Kappa value of 0.86. The Dempster–Shafer ambiguity underlines the good quality of the training sites and the probability guided spectral unmixing is chosen for the determination of plant functional types for the land model. A similar model run with a spatial distribution of land cover from both the hard and the soft classification processes clearly points to more realistic model results by using the land surface based on the probability guided spectral unmixing technique.

Ground Fog Detection from Space Based on MODIS Daytime Data—A Feasibility Study

Abstract The distinction made by satellite data between ground fog and low stratus is still an open problem. A proper detection scheme would need to make a determination between low stratus thickness and top height. Based on this information, stratus base height can be computed and compared with terrain height at a specific picture element. In the current paper, a procedure for making the distinction between ground fog and low-level stratus is proposed based on Moderate Resolution Imaging Spectroradiometer (MODIS, flying on board the NASA Terra and Aqua satellites) daytime data for Germany. Stratus thickness is alternatively derived from either empirical relationships or a newly developed retrieval scheme (lookup table approach), which relies on multiband albedo and radiative transfer calculations. A trispectral visible–near-infrared (VIS–NIR) approach has been proven to give the best results for the calculation of geometrical thickness. The comparison of horizontal visibility data from synoptic observing...

A feasibility study of daytime fog and low stratus detection with TERRA/AQUA‐MODIS over land

A scheme for the detection of fog and low stratus over land during daytime based on data of the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument is presented. The method is based on an initial threshold test procedure in the MODIS solar bands 1–7 (0.62–2.155µm). Fog and low stratus detection generally relies on the definition of minimum and maximum fog and low stratus properties, which are converted to spectral thresholds by means of radiative transfer calculations (RTC). Extended sensitivity studies reveal that thresholds mainly depend on the solar zenith angle and, hence, illumination-dependent threshold functions are developed. Areas covered by snow, ice and mid-/high-level clouds as well as bright/hazy land surfaces are omitted from the initial classification result by means of a subsequent cloud-top height test based on MODIS IR band 31 (at 12 µm) and a NIR/VIS ratio test. The validation of the final fog and low stratus mask generally shows a satisfactory performance of the scheme. Validation problems occur due to the late overpass time of the TERRA platform and the time lag between SYNOP and satellite observations. Apparent misclassifications are mainly found at the edge of the fog layers, probably due to over- or underestimation of fog and low stratus cover in the transition zone from fog to haze. Copyright

Detecting ground fog from space-a microphysics-based approach

The detection of ground fog from satellite data is of interest in operational nowcasting applications, as well as in studies of the climate system. A discrimination between fog at the ground and other low-stratus situations from satellite data requires information on cloud vertical geometry to establish whether the cloud touches the ground. This article introduces a technique that allows for the discrimination between low stratus and (ground) fog on the basis of geostationary satellite imagery. The cloud-base height is derived using a subadiabatic model of cloud microphysics. In this model, the cloud base is varied until model liquid–water path matches that retrieved from satellite data. The performance of this technique is shown to be good in a comparison with METeorological Aerodrome Report data comprising 1030 satellite scenes. With a hit rate of 81% and a threat score of 0.62, the skill is satisfactory.

Growth of Tropical Bracken (Pteridium arachnoideum): Response to Weather Variations and Burning

Abstract The ecology of tropical bracken, which occurs in tropical regions, is not well known. We studied its response to weather variations and burning in the south Ecuadorian Andes, where this weed had already overgrown 40% of the pastureland. In field observations, a constant 1 : 1 ratio of emerging and dying leaves suggested limitation of frond density by nutrient shortage. Short-term deviations from that ratio could be related to weather variations. Spells of dry weather temporarily increased mortality but stimulated emergence of new fronds. Lifespan of the fronds produced immediately after a fire was longer than of those produced during unaffected bracken growth. A burst of frond development during the initial 2 to 3 mo was observed after a fire followed by self-thinning to a stable level. To analyze the effect of fire on bracken, rhizomes were treated with heat pulses. Rhizomes were heat tolerant up to 70 C, and frond production from short shoots was enhanced by elevated temperature. Burning apparently releases apical dominance of developed fronds, as does cutting, and stimulates bud break. The local practice of pasture maintenance in Ecuador of repeated burning favors growth of the fern. Nomenclature: Bracken, Pteridium aquilinum agg. (L.) Kuhn; tropical bracken (bracken of the southern hemisphere), e.g., neotropical Pteridium arachnoideum (Kaulf.) Maxon and Pteridium caudatum (L.) Maxon

DEWFALL AS A WATER SOURCE FREQUENTLY ACTIVATES THE ENDOLITHIC CYANOBACTERIAL COMMUNITIES IN THE GRANITES OF TAYLOR VALLEY, ANTARCTICA1

Endolithic photosynthetic microorganisms like cyanobacteria and algae are well known from savannas and deserts of the world, the high Arctic, and also Antarctic habitats like the Dry Valleys in the Ross Dependency. These endolithic microbial communities are thought to be at the limits of life with reported ages in the order of thousands of years. Here we report on an extensive chasmoendolithic cyanobacterial community inside granite rocks of Mt. Falconer in the lower Taylor Valley, Dry Valleys. On average, the cyanobacterial community was 4.49 ± 0.95 mm below the rock surface, where it formed a blue‐green layer. The community was composed mainly of the cyanobacterium Chroococcidiopsis sp., with occasional Cyanothece cf. aeruginosa (Nägeli) Komárek and Nostoc sp. Mean biomass was 168 ± 44 g carbon · m−2, and the mean chl a content was 24.3 ± 34.2 mg · m−2. In situ chl fluorescence measurements—a relative measure of photosynthetic activity—showed that they were active over long periods each day and also showed activity the next day in the absence of any moisture. Radiocarbon dating gave a relatively young age (175–280 years) for the community. Calculations from microclimate data demonstrated that formation of dew or rime was possible and could frequently activate the cyanobacteria and may explain the younger age of microbial communities at Mt. Falconer compared to older and less active endolithic microorganisms reported earlier from Linnaeus Terrace, a higher altitude region that experiences colder, drier conditions.

Comparison of Different Techniques for the Measurement of Precipitation in Tropical Montane Rain Forest Regions

Abstract Characteristics of different precipitation measurements in a tropical mountain valley in southern Ecuador are compared in this study to determine potential errors. The instruments are used for different ecological purposes like erosion studies, through fall measurements, investigation of atmospheric chemistry, and modeling of area rainfall distribution. Five recording devices (two precipitation radars, an electro-optical present weather sensor, and two tipping buckets) and three totaling gauges were operated in parallel at a designated site. Data were taken between 1998 and 2003 with different temporal resolution and different operational periods. The general agreement between the instruments is rather good; deviations are in the expected range of 10%–20% of the annual total of about 2200 mm. The remote sensing devices are superior in registering the frequent occurrence of light rain but are not capable of detecting the full range of rain intensities observed. The tipping buckets and the totaling...