We study the effects of plants and root-associated fungi on wind erosion within the alpine environment of Tibet. China is one of the countries most affected by desertification processes and Tibet, in particular, a key region in desertification combat. The presented project focuses on the Barkha Plain surrounded by Mount Kailash and the Lake of Manasarovar (Ngari Prefecture). This Western Tibet region experienced little scientific attention but, nowadays, faces rapidly increasing touristic activities and expanding local settlements associated with socio-economic changes that are serious threats to the delicate ecological balance and potential triggers of desertification. It exists almost unanimous agreement that revegetation is the most efficient and promising strategy to combat wind erosion and desertification in the long term. However, re-colonising success is often poor, mainly under extreme environmental conditions. Compared to conventional practices, the approach of the presented project attains better accordance with natural succession processes and promises acceleration of both plant and soil development and, conclusively, more efficient desertification control. The project assesses the potential of native plants and symbiotic fungi to control wind erosion and desertification processes. It aims to identify key plants and fungi that increase soil aggregate stability and efficiently drive succession into a natural and self-maintaining cycle of the ecosystem. Furthermore, it provides crucial information for implementing environmentally compatible and cost-effective measures to protect high-elevation ecosystems against desertification. Within three successional stages (early, intermediate, late), field investigations are performed on the basis of Modified-Whittaker plots. Classic methods of vegetation analysis and myco-sociology are combined with analysis of distribution patterns at different scales (patchiness, connectivity). Comprehensive soil analysis is performed comprising grain size distribution, aggregate stability, pH as well as water and nutrient contents. Additionally, important parameters of wind erosion are measured concurrently and continuously to assess their magnitude and variability with respect to vegetation and soil at different levels of development. The parameters addressed, include sediment transport, air temperature, radiation, precipitation, relative humidity as well as speed and direction of wind. Surface moisture is recorded periodically and roughness described. Species and environmental parameters are checked for spatial correlation. Cutting edge technologies are applied in laboratory work, comprising molecular methods for fungal species identification and micro-tomography to analyse soil structure. Furthermore, successfully cultivated fungi and plants are subject of synthesis experiments and industrial propagation in view of practical implementation in restoration measures.
Laminierte Seesedimente sind unschätzbare Informationsquellen zur Geschichte der Umwelt und des Klimas direkt aus der Lebenssphäre des Menschen. Ein exzellentes Beispiel dafür ist der Sihailongwan-Maarsee aus NE-China. In einem immer noch dicht bewaldeten Vulkangebiet gelegen, bieten seine Sedimente ein ungestörtes Abbild der Monsunvariationen über zehntausende von Jahren. Nur die letzten ca. 200 Jahre zeigen einen deutlichen lokalen anthropogenen Einfluss. Das Monsunklima der Region mit Hauptniederschlägen während des Sommers und extrem kalten Wintern unter dem Einfluss des Sibirischen Hochdrucksystems bildet die Voraussetzung für die Bildung von saisonal deutlich geschichteten Sedimenten (Warven), die in dem tiefen Maarsee dann auch überwiegend ungestört erhalten bleiben. Insbesondere die Auftauphase im Frühjahr bringt einen regelmässigen Sedimenteintrag in den See, der das Gerüst für eine derzeit bis 65.000 Jahre vor heute zurückreichende Warvenchronologie bildet. Für das letzte Glazial zeigen Pollenspektren aus dem Sihailongwan-Profil Vegetationsvariationen im Gleichklang mit bekannten klimatischen Variationen des zirkum-nordatlantischen Raumes (Dansgaard-Oeschger-Zyklen) zu dieser Zeit. Der Einfluss dieser Warmphasen auf das Ökosystem See war jedoch sehr unterschiedlich. So sind die Warven aus den Dansgaard-Oeschger (D/O) Zyklen 14 bis 17 mit extrem dicken Diatomeenlagen (hauptsächlich Stephanodiscus parvus/minutulus) denen vom Beginn der spätglazialen Erwärmung zum Verwechseln ähnlich, während Warven aus dem D/O-Zyklus 8 kaum Unterschiede zu überwiegend klastischen Warven aus kalten Interstadialen aufweisen. Gradierte Ereignislagen mit umgelagertem Bodenmaterial sind deutliche Hinweise auf ein Permafrost-Regime während der Kaltphasen. Auch während des Spätglazials treten deutliche klimatische Schwankungen auf, die der in europäischen Sedimentarchiven definierten Gerzensee-Oszillation und der Jüngeren Dryas zeitlich exakt entsprechen. Das frühe Holozän ist von einer Vielzahl Chinesischer Paläoklima-Archive als Phase mit intensiverem Sommermonsun bekannt. Überraschenderweise sind die minerogenen Fluxraten im Sihailongwan-See während des frühen Holozäns trotz dichter Bewaldung des Einzugsgebietes sehr hoch. Sowohl Mikrofaziesanalysen der Sedimente als auch geochemische Untersuchungen deuten auf remoten Staub als Ursache dieses verstärkten klastischen Eintrags hin. Der insbesondere in den letzten Jahrzehnten zunehmende Einfluss des Menschen zeigt sich in den Sedimenten des Sihailongwan-Maarsees vor allem in einem wiederum zunehmenden Staubeintrag und einer Versauerung im Einzugsgebiet. Der anthropogene Einflusss auf die lokale Vegetation ist immer noch gering.
In recent years science has taken an increased interest in mineralization processes in tropical soils in particular under minimal tillage operations. Plant litter quality and management strongly affect mineralization-nitrification processes in soil and hence the fate of nitrogen in ecosystems and the environment. Plant secondary metabolites like lignin and polyphenols are poorly degradable and interact with proteins (protein binding capacity) and hence protect them from microbial attack. Nitrification, a microbiological process, directly and indirectly influences the efficiency of recovery of N in the vegetation as well as the loss of N (through denitrification and leaching) causing environmental pollution to water bodies and contributes to global warming (e.g. the greenhouse gas N2O is emitted as a by-product of nitrification and denitrification). Nitrifiers comprise a relatively narrow species diversity (at least as known to date) and are generally thought to be sensitive to low soil pH and stress. Despite these properties nitrification occurs in acid tropical soils with high levels of aluminium and manganese. Thus the main objective of the project will be the identification of micro-organisms and mechanisms responsible for mineralization-nitrification processes in acid tropical soils and the influence of long-term litter input of different chemical qualities and minimal tillage options. The project will include the use of stable isotopes (15N, 13C), mass spectrometry, gas chromatography (CO2, N2O), biochemical methods (PLFA) and molecular biology (16s rRNA., PCR, DGGE)
Most soils develop distinct soil architecture during pedogenesis and soil organic carbon (SOC) is sequestered within a hierarchical system of mineral-organic associations and aggregates. Permafrost soils store large amounts of carbon due to their permanently frozen subsoil and a lack of oxygen in the active layer, but they lack complex soil structure. With permafrost thaw more oxidative conditions and increasing soil temperature presumably enhance the build-up of more complex units of soil architecture and may counterbalance, at least partly, SOC mineralization. We aim to explore the development of mineral-organic associations and aggregates under different permafrost impact with respect to SOC stabilization. This information will be linked to environmental control factors relevant for SOC turnover at the pedon and stand scale to bridge processes occurring at the aggregate scale to larger spatial dimensions. We will combine in situ spectroscopic techniques with fractionation approaches and identify mechanisms relevant for SOC turnover at different scales by multivariate statistics and variogram analyses. From this we expect a deeper knowledge about soil architecture formation in the transition of permafrost soils to terrestrial soils and a scale-spanning mechanistic understanding of SOC cycling in permafrost regions.
Der asiatische Sommermonsun ist charakterisiert durch hohe Konvektion über Südasien, die mit der asiatischen Monsun-Antizyklone (AMA) zusammenhängt, der sich von der oberen Troposphäre bis in die untere Stratosphäre (UTLS) erstreckt. Diese Antizyclone ist das ausgeprägteste Zirkulationsmuster in diesen Höhen während des borealen Sommer. Es ist bekannt, dass der Export von Monsunluft quasi-isentropisch aus der AMA sowohl im Osten als auch im Westen, einen großen Einfluss auf die Zusammensetzung der außertropischen unteren Stratosphäre hat. Jedoch sind die relative Stärken der beiden Wege bisher unbekannt. Der Transport von Luftmassen aus der AMA in die nördliche außertropische UTLS wirkt sich entscheidend auf die Chemie der Stratosphäre und ihrenStrahlungshaushalt (z.B. durch Transport von H2O, Aerosol oder ozonschädigende Stoffe) aus. Im Rahmen dieses Projekts AirExam wird der quasi-isentropischer Luftmassenexport aus der AMA durch verschiedene Wegen und seine Auswirkungen auf Chemie und Strahlung der außertropische UTLS quantifiziert durch u.a. HALO-Flugzeugmessungen (insbesondere aus die für Sommer 2023 geplanten PHILEAS-Kampagne), Simulationen mit dem Chemischen Transportmodell CLaMS und Strahlungsberechnungen. Unser Projekt AirExam wird sich mit den folgenden offenen Schlüsselfragen befassen:1) Welchen relativen Beitrag leisten die beiden quasi-horizontalen Transportwege (nach Westen und Osten) aus dem asiatischen Monsun-Antizyklon zur Zusammensetzung der außertropischen unteren Stratosphäre?2) Wie groß ist die jährliche Variabilität des Transports aus der asiatischen Monsun-Antizyklone in die außertropische untere Stratosphäre und was sind die Hauptquellenregionen auf der Erde Oberfläche?3) Was ist die Auswirkung des Wasserdampftransports aus der asiatischen Monsun-Antizyklone zum H2O-Budget der außertropischen UTLS und seine Strahlungswirkung?In unserem Projekt werden wir HALO-Messungen (insbesondere H2O) mit globalen 3-dimensionalen CLaMS-Simulationen kombinieren, die von neuen hochaufgelösten ERA-5-Reanalyse des ECMWF angetrieben werden. CLaMS-Simulationen auf der Grundlage von ERA-5 sind ein neues Instrument zur zuverlässigen Beschreibung von Transportprozessen in der Region des asiatischen Monsuns und seiner globalen Auswirkungen. Die Strahlungswirkung des durch den asiatischen Monsun verursachten H2O-Anstiegs im Sommer und Herbst wird mit Hilfe des Strahlungs-Transfercodes Edwards und Slingo berechnet. H2O ist das wichtigste Treibhausgas, und die Befeuchtung der Stratosphäre ist eine wichtige Triebkraft des Klimawandels. Unser Projekt AirExam wird die Auswirkungen des verstärkten H2O-Transports in die untere Stratosphäre quantifizieren und kann daher dazu beitragen, die potenziellen Risiken des Luftmassentransports aus der asiatischen Monsunregion auf die globale Stratosphäre zu bewerten.
Irrigation in the Yanqi Basin, Sinkiang, China has led to water table rise and soil salination. A model is used to assess management options. These include more irrigation with groundwater, water saving irrigation techniques and others. The model relies on input data from remote sensing.The Yanqi Basin is located in the north-western Chinese province of Xinjiang.This agriculturally highly productive region is heavily irrigated with water drawn from the Kaidu River. The Kaidu River itself is mainly fed by snow and glacier melt from the Tian Mountain surrounding the basin. A very poor drainage system and an overexploitation of surface water have lead to a series of environmental problems: 1. Seepage water under irrigated fields has raised the groundwater table during the last years, causing strongly increased groundwater evaporation. The salt dissolved in the groundwater accumulates at the soil surface as the groundwater evaporates. This soil salinization leads to degradation of vegetation as well as to a loss of arable farmland. 2. The runoff from the Bostan Lake to the downstream Corridor is limited since large amount of water is used for irrigation in the Yanqi Basin. Nowadays, the runoff is maintained by pumping water from the lake to the river. The environmental and ecological system is facing a serious threat.In order to improve the situation in the Yanqi Basin, a jointly funded cooperation has been set up by the Institute of Environmental Engineering, Swiss Federal Institute of Technology (ETH) , China Institute of Geological and Environmental Monitoring (CIGEM) and Xinjiang Agricultural University. The situation could in principle be improved by using groundwater for irrigation, thus lowering the groundwater table and saving unproductive evaporation. However, this is associated with higher cost as groundwater has to be pumped. The major decision variable to steer the system into a desirable state is thus the ratio of irrigation water pumped from the aquifer and irrigation water drawn from the river. The basis to evaluate the ideal ratio between river and groundwater - applied to irrigation - will be a groundwater model combined with models describing the processes of the unsaturated zone. The project will focus on the following aspects of research: (...)
Blattaelchen (Aphelenchoides fragariae, A. ritzemabosi) und Viren koennen in befallenen Erdbeerbestaenden erhebliche Ernteverluste verursachen. Mit Hilfe der Waermetherapie ist unter bestimmten Voraussetzungen moeglich, von virusverseuchten Erdbeersorten wieder gesunde fuer die Vermehrung geeignete Pflanzen zu gewinnen. Bisher wurden hierfuer eine Warmluftbehandlung durchgefuehrt. Es soll nun geklaert werden, ob fuer diesen Zweck auch eine Warmwasserbehandlung geeignet ist. Dieses Verfahren kann ebenfalls zur Bekaempfung der Blattaelchen angewandt werden. Bei einer Wirksamkeit der Warmwasserbehandlung gegen beide Schadenursachen koennte ausser einer Einsparung von Pflanzenschutzmitteln auch ein erheblicher wirtschaftlicher Vorteil erzielt werden.
Nutrient and water supply for organisms in soil is strongly affected by the physical and physico-chemical properties of the microenvironment, i.e. pore space topology (pore size, tortuosity, connectivity) and pore surface properties (surface charge, surface energy). Spatial decoupling of biological processes through the physical (spatial) separation of SOM, microorganisms and extracellular enzyme activity is apparently one of the most important factors leading to the protection and stabilization of soil organic matter (SOM) in subsoils. However, it is largely unknown, if physical constraints can explain the very low turnover rates of organic carbon in subsoils. Hence, the objective of P4 is to combine the information from the physical structure of the soil (local bulk density, macropore structure, aggregation, texture gradients) with surface properties of particles or aggregate surfaces to obtain a comprehensive set of physical important parameters. It is the goal to determine how relevant these physical factors in the subsoil are to enforce the hydraulic heterogeneity of the subsoil flow system during wetting and drying. Our hypothesis is that increasing water repellency enforces the moisture pattern heterogeneity caused already by geometrical factors. Pore space heterogeneity will be assessed by the bulk density patterns via x-ray radiography. Local pattern of soil moisture is evaluated by the difference of X-ray signals of dry and wet soil (project partner H.J. Vogel, UFZ Halle). With the innovative combination of three methods (high resolution X-ray radiography, small scale contact angle mapping, both applied to a flow cell shaped sample with undisturbed soil) it will be determined if the impact of water repellency leads to an increase in the hydraulic flow field heterogeneity of the unsaturated sample, i.e. during infiltration events and the following redistribution phase. An interdisciplinary cooperation within the research program is the important link which is realized by using the same flow cell samples to match the spatial patterns of physical, chemical, and biological factors in undisturbed subsoil. This cooperation with respect to spatial pattern analysis will include the analysis of enzyme activities within and outside of flow paths and the spatial distribution of key soil properties (texture, organic carbon, iron oxide content) evaluated by IR mapping. To study dissolved organic matter (DOM) sorption in soils of varying mineral composition and the selective association of DOM with mineral surfaces in context with recognized flow field pattern, we will conduct a central DOM leaching experiment and the coating of iron oxides which are placed inside the flow cell during percolation with marked DOM solution. Overall objective is to elucidate if spatial separation of degrading organisms and enzymes from the substrates may be interconnected with defined physical features of the soil matrix thus explaining subsoil SOM stability and -dynami
Background: Ghanas transition forests, neighbouring savannahs and timber plantations in the Ashanti region face a constant degradation due to the increased occurrence of fires. In most cases the fires are deliberately set by rural people for hunting purposes. Main target is a cane rat, here called grasscutter (Thryonomys swinderianus), whose bushmeat is highly esteemed throughout the country. The animal is a wild herbivorous rodent of subhumid areas in Africa south of the Sahara. The grasscutter meat is an important source of animal protein. Existing high-value timber plantations (mainly Teak, Tectona grandis) are affected by fires for hunting purposes. Thus resulting in growth reduction, loss of biomass or even complete destruction of the forest stands. It became obvious that solutions had to be sought for the reduction of the fire risk. Objectives: Since 2004 the Institute for World Forestry of the Federal Research Centre for Forestry and Forest Products, Hamburg, Germany is cooperating with a Ghanaian timber plantation company (DuPaul Wood Treatment Ltd.) the German Foundation for Forest Conservation in Africa (Stiftung Walderhaltung in Afrika) and the Center for International Migration with the purpose to improve the livelihood of the rural population in the surroundings of the forest plantation sites and simultaneously to safeguard and improve the timber plantations. The introduction of grasscutter rearing systems to local farmers accompanied by permanent agricultural and agroforestry practices appeared to be a promising approach for the prevention of fires in the susceptible areas. Additionally a functioning grasscutter breeding system could contribute to the improvement of food security, development of income sources and the alleviation of poverty. The following measures are implemented: - Identification of farmers interested in grasscutter captive breeding, - Implementation of training courses for farmers on grasscutter rearing, - Delivery of breeding animals, - Supervision of rearing conditions by project staff, - Development of a local extension service for monitoring activities, - Evaluation of structures for grasscutter meat marketing. Results: After identification of key persons for animal rearing training courses were successfully passed and animals were delivered subsequently. Further investigations will evaluate the effects of the grasscutter rearing in the project region. This will be assessed through the - Acceptance of grasscutter rearing by farmers, - Success of the animal caging, - Reproduction rate, - Meat quality, - Marketing success of meat, - Reduction of fire in the vicinity of the timber plantations, - Improvement of peoples livelihood.
Background: An increasing frequency of massive flooding along the lower Yangtse River in China ended in a disastrous catastrophe in summer 1998 leaving several thousand people homeless, more than 3.600 dead and causing enormous economic damage. Inappropriate land-use techniques and large scale timber felling in the water catchment of the upper Yangtse and its feeder streams were stated to be the main causes. Immediate timber cutting bans were imposed and investigations on land use patterns were initiated by the Chinese Government. The Institute for World Forestry of the Federal Research Centre for Forestry and Forest Products was approached by the Yunnan Academy of Forestry in Kunming to exchange experiences and to cooperate scientifically in the design and application of appropriate afforestation and silvicultural management techniques in the water catchment area of the Yangtse. This cooperation was initiated in 1999 and is based on formal agreements in the fields of agrarian research between the German and Chinese Governments. Objectives: The cooperation was in the first step focussing on the identification of factors which caused the enormous floodings. After their identification measures of prevention were determined and put into practice. In this context experiences made in past centuries in the alpine region of central Europe served as an incentive and example for similar environmental problems and solutions under comparable conditions. Relevant key questions of the cooperation project were: - Analysis of forest related factors influencing the recent floodings of the Yangtse, - Analysis and evaluation of silvicultural management experiences from central Europe for know-how transfer, - Evaluation of rehabilitation measures for successful application in Yunnan, - Dissemination of knowledge through vocational training. Results: - Frequent wild grazing of husbandry is a key factor for forest degeneration beyond unsustainable timber harvests, forest fires and insect calamities leading to increased water run-off in the mountainous region of Yunnan; - Browsing of cattle interrupts succession thus avoiding natural regeneration and leaving a logging ban ineffective; - Mountain pasture in the Alps had similar effects in the past in central Europe. The introduction of controlled grazing has led to an ecologically compatible coexistence of pasture and ecology. Close-to-nature forestry can have positive effects in this sensitive environment. - Afforestation with site adopted broadleaves and coniferous tree species was implemented on demonstration level using advanced techniques in Yunnan.
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