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  • 1
    Language: English
    In: Journal of Hydrology, 12 November 2012, Vol.470-471, pp.184-192
    Description: ► A novel dye tracer experiment for root channelization of stemflow was designed. ► Stemflow concentrates water over localized circular areas at the tree base. ► Infiltrating stemflow water was funneled belowground along the roots. ► Stemflow and root induced preferential flow triggers a fast response to rainstorms. The aim of this study was to determine how the crown and root architecture of beech trees control stemflow formation, stemflow infiltration, and the subsurface transport of stemflow through the soil with a novel dye tracer experiment. With this approach, it is possible to apply the dye solution directly to the stem, enabling a more advanced technique to represent the flow processes than has been used in previous studies. Stemflow concentrates and channels water over localized circular areas at the tree base, as shown in this study. Tracing stemflow using dye demonstrated that infiltrating stemflow water was preferentially funneled belowground along heart and sinker roots, laterally oriented coarse roots, and congregations of fine roots grown into decayed root channels of felled trees. The results presented in this study reveal that stemflow and root induced preferential flow triggers fast lateral subsurface flow bypassing large parts of the soil matrix at least during rainstorm events. Based on our measurements, we hypothesize that the formation of stemflow and the channeling of infiltrating stemflow water along the roots of beech trees might be an important mechanism of runoff generation in forested catchments.
    Keywords: Preferential Flow ; Stemflow ; Ecohydrology ; Runoff Generation ; Root Network ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 2
    Language: English
    In: Journal of Hydrology, 07 June 2013, Vol.492, pp.176-189
    Description: Numerical water balance models are widely used in ecological and hydro sciences. However, their application is related to specific problems and uncertainties. The reliability of model prediction depends on (i) model concept, (ii) parameters, (iii) uncertainty of input data, and (iv) uncertainty of reference data. How model concept (i) and parameters (ii) effect the model’s performance is an often treated problem. However, the effects of (iii) and (iv) are typically ignored or only barely treated in context of regionalisation and generalisation. In this study, the actual measurement uncertainties of input and reference data are the main focus. Furthermore, the evaluation of model results is analysed with regard to uncertainties of reference data. A special feature is the use of evapotranspiration (measured via the eddy covariance) instead of runoff for evaluation of simulation results. It is shown that seemingly small uncertainties of measurements can create significant uncertainties in simulation results depending on the temporal scale of investigation. As an example, the uncertainty of measurements of daily global radiation sum up to an uncertainty of 250 MJ (equivalent to 100 mm) on an annual scale, which causes an uncertainty of 40 mm in simulated grass-reverence evapotranspiration. Summarised and generalised, the measurement uncertainties of all input data create an uncertainty on average of around 5% in the simulated annual evapotranspiration and of around 10% in the simulated annual seepage. However, the effects can be significantly higher in years with extreme events and can reach up to 15%. It is demonstrated that uncertainties of individual variables are not simply superposed but interact in a complex way. Thereby, it has become apparent that the effects of measurement uncertainties on model results are similar for complex and for simple models.
    Keywords: Eddy Covariance ; Brook90 ; Model Complexity ; Monte Carlo Simulation ; Observation Uncertainty ; Parameter Uncertainty ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 3
    Language: English
    In: Sustainability, 01 December 2017, Vol.9(12), p.2362
    Description: Pressing issues such as water and food security, health, peace, and poverty are deeply linked to land degradation. We use China’s major land restoration programs as a case offering perspective on the existing problems in China’s major policies for improving degraded land and maintaining land resources in three dimensions. The shortcomings and outcomes in terms of biophysical consequences, socioeconomic benefits, and political goals are addressed, namely (i) non-integrated land resources management creates new problems while solving existing problems, (ii) non-participatory processes and “one-size-fits-all” measures compromise socioeconomic benefits, and (iii) implementation outcomes conflict with policy targets for sustainable land management and development. Based on discussions for more sustainable land management, we conclude that China needs to create a new mode of ‘economy and environment’ in plans and actions of restoring degraded land resources. Establishing multifunctional land-use systems based on formulating and balancing multiple benefits/services across socio-ecological sectors can be an option to achieve such a mode. At the end, recommendations are given for research and implementation that are not only vital for China but also relevant for other regions since the challenges of afforestation and sustainable land development faced in China are not unique.
    Keywords: Land Degradation ; Sustainable Land Management ; Afforestation ; Multifunctional Land Use ; Ecosystem Functions and Services ; Environmental Sciences ; Economics
    E-ISSN: 2071-1050
    Source: Directory of Open Access Journals (DOAJ)
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  • 4
    Language: English
    In: Soil Science Society of America Journal, 2013, Vol.77(6), p.2157
    Description: The thermal regime of a large field lysimeter should be the same as of the surrounding soil. It is assumed that lysimeters with a construction depth larger than the expected root zone meet this condition. However, the installation of such large lysimeters is costly and not always feasible. Thus, a new method for the control of soil temperature at the lower boundary of large field lysimeters was developed. Our method enables for easy and prompt control of the soil temperature at the bottom of lysimeters. Differences in soil temperature between the lysimeter and surrounding soil increased to 1.6°C when the temperature control was switched off. The significance of the automated soil temperature control is twofold. First, the reliability of lysimeter measurements can be improved. Second, shallower lysimeters can be constructed. This significantly reduces the installation costs of field lysimeters. [PUBLICATION ]
    Keywords: Vegetables ; Automation ; Studies ; Heat Conductivity ; Soils ; Temperature;
    ISSN: Soil Science Society of America Journal
    E-ISSN: 0361-5995
    E-ISSN: 14350661
    Source: CrossRef
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  • 5
    Language: English
    In: 한국토양비료학회 학술발표회 초록집, 2014, Vol.2014(6), pp.225-225
    Keywords: Soil Pore-Space Changes ; Soil Hydraulic Properties ; Land Use ; Soil Management ; Temporal Variability
    Source: DBpia - 디비피아 (Nurimedia)
    Source: DBpia (Nurimedia)
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  • 6
    Language: English
    In: Forests, 01 April 2018, Vol.9(4), p.201
    Description: Black locust (Robinia pseudoacacia L.) is a major tree species in China’s large-scale afforestation. Despite its significance, black locust is underrepresented in sap flow literature; moreover, the published water consumption data might be biased. We applied two field methods to estimate water consumption of black locust during the growing seasons in 2012 and 2013. The application of Granier’s original sap flow method produced a very low transpiration rate (0.08 mm d−1) while the soil water balance method yielded a much higher rate (1.4 mm d−1). A dye experiment to determine the active sapwood area showed that only the outermost annual ring is responsible for conducting water, which was not considered in many previous studies. Moreover, an in situ calibration experiment was conducted to improve the reliability of Granier’s method. Validation showed a good agreement in estimates of the transpiration rate between the different methods. It is known from many studies that black locust plantations contribute to the significant decline of discharge in the Yellow River basin. Our estimate of tree transpiration at stand scale confirms these results. This study provides a basis for and advances the argument for the development of more sustainable forest management strategies, which better balance forest-related ecosystem services such as soil conservation and water supply.
    Keywords: Afforestation ; Heat Dissipation Probes ; in Situ Calibration ; Soil Water Balance ; Transpiration ; Dye Tests ; Ring-Porous Trees ; Forestry
    E-ISSN: 1999-4907
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  • 7
    Language: English
    In: European Journal of Forest Research, 2011, Vol.130(5), pp.695-706
    Description: The aim of this study was to investigate transpiration and its main driving factors on the example of a hybrid poplar plantation with the clone Populus maximowiczii × P. nigra , cv. Max 1 on a site in the hilly loess region of Saxony (Germany). Transpiration was measured using sap flow techniques during the 2007 and 2008 growing season. At the same time, throughfall, soil moisture dynamics and soil physical properties were also measured. Total transpiration rates amounted to 486 mm and 463 mm, respectively, during the 2 years. Maximum daily transpiration rates reached 6.7 mm/day, while an average of 2.2 mm/day for the entire growing season was recorded. The main controlling factors for stand transpiration included the evaporative demand, water availability and soil temperature. The information was implemented into a simple empirical model for the prediction of transpiration. It can be concluded that large-scale establishment of poplar plantations will result in a distinct reduction in groundwater recharge. On the other hand, surface run-off and soil erosion may decrease. Due to limited water availability in the late growing season, the growth potential of the tested clone cannot fully be exploited at many sites in Germany.
    Keywords: Evapotranspiration ; Soil water ; Poplar ; Plantation ; Sap flow
    ISSN: 1612-4669
    E-ISSN: 1612-4677
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  • 8
    Language: English
    In: Journal of Arid Environments, September 2015, Vol.120, pp.42-50
    Description: Large-scale vegetation restoration and climate change triggered a significant decline in runoff in the middle reaches of the Yellow River and its tributaries. This runoff decline intensifies inherent water shortage and results in more severe water use conflicts that are threatening sustainable development in the Loess Plateau. Innovative strategies for more water-efficient land management are essential. To this end, the factors controlling runoff were investigated using the upstream area of the Jing River as an example. Runoff was found to be mainly controlled by evaporative demand, precipitation, and land cover type. Budyko's frameworks were applied to predict the annual and long-term runoff; however, the effect of changes in land management ( , afforestation) on runoff cannot be assessed due to lack of vegetation factors. Therefore, an empirical analysis tool was derived based on an existing relationship for runoff estimation. This method was found to be more effective in reproducing the annual and long-term runoff than others. The incorporation of temporal changes in land cover and form in approach enables the estimation of the possible impact of soil conservation measures ( , afforestation or terracing). Our study highlights the importance of adaptive land management strategies for mitigating water shortage on the Loess Plateau.
    Keywords: Runoff Reduction ; Climate Change ; Land-Use Pattern ; Soil Erosion ; Water Resources Management ; Empirical Method ; Environmental Sciences ; Geography ; Ecology
    ISSN: 0140-1963
    E-ISSN: 1095-922X
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  • 9
    Language: English
    In: Agricultural and Forest Meteorology, 2011, Vol.151(8), pp.1023-1034
    Description: ► Events explained residual inter-annual variation of stand transpiration of spruce. ► Ec from June to July and Ec were good predictors of annual stand water uptake. ► Relative canopy precipitation used for transpiration remained stable during years. ► Frequency of precipitation was negatively correlated with monthly Ec. At the study site Tharandt Anchor Station in Saxony/Germany sap flow measurements are conducted in an old Norway spruce ( [L.] KARST.) stand. During the study period from 2001 to 2007 several events like thinning, long and short drought periods and a winter storm significantly affected the amount of canopy water use. We show that intra-annual variation of Ec is strongly related to VPD and PPFD. While there is a non-linear relationship between daily Ec and VPD, daily Ec is limited by daily integrated PPFD indicating stomatal control of Ec through photosynthesis. On a monthly or seasonal basis, reduction of Ec is not only related to high VPD and non-saturating PPFD, but also to higher frequencies of precipitation. In comparison to this, nearly 55% of canopy precipitation and 20% of available energy were used for transpiration during the growing season. Intensive seasonal soil water measurements at the site revealed that on average about 74% of soil water removal within the rooting zone can be related to tree water uptake. A good correlation was found between annual Ec and Ec , usually occurring in June or July. Further, the monthly sums of June plus July were good predictors of annual Ec. Within the study period, the extreme drought in 2003 revealed a clear threshold of soil water content by 9.5 vol% and had the most pronounced effect on annual Ec followed by a stand thinning. The winter storm “Kyrill” in January 2007 had caused loss of green needles and twigs. It is assumed that the observed reduction in Ec during spring was related to the reduced leaf biomass and potentially to root damage of bended trees. Excluding the effect of extreme drought and forest management, a mean inter-annual variation in Ec of ±15% and in Ec/VPD of ±8% remained. It is concluded that lag-effects of drought and the winter storm add lacking explanation to the inter-annual variability of canopy transpiration besides the typical variation of atmospheric conditions.
    Keywords: Picea Abies ; Inter-Annual Variability ; Extreme Events ; Thinning ; Plant Available Water ; Canopy Precipitation ; Agriculture ; Meteorology & Climatology
    ISSN: 0168-1923
    E-ISSN: 1873-2240
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  • 10
    Language: English
    In: Environmental Earth Sciences, 2012, Vol.65(5), pp.1501-1510
    Description: Integrated watershed models require spatially differentiated soil information. However, in many regions of the world the limited availability of soil data hinders an appropriate simulation of hydro-ecological processes. Such circumstances lead to unsupported statements, poor statistics, misrepresentations, and, ultimately, to bad resource management. The Western Bug catchment in west Ukraine is an example of such a region. In the former Soviet Union, soil classification primarily focused on soils of agricultural importance, whereas, forested, urban, industrial, and shallow soil territories were left underrepresented in the classification and soil maps. Spatially differentiated soil texture data are required to predict soil hydraulic properties using pedotransfer functions (PTFs), along with soil maps. Furthermore, the Ukrainian soil texture scheme does not match the particle size classes commonly used with PTFs. To overcome these shortcomings, a fuzzy logic methodology was applied, based on terrain and vegetation/land use analysis and soil sampling, to close the information gaps. For the application of PTFs, a procedure was tested to estimate missing values of soil texture distribution. Applied methods were evaluated using recent soil surveys, measured soil texture, and water retention properties, while having in consideration the limitations brought by scarce soil data for integrated watershed modelling purposes.
    Keywords: Watershed modelling ; Soil mapping ; Fuzzy logic ; SoLIM ; Pedotransfer function ; Particle size distributions
    ISSN: 1866-6280
    E-ISSN: 1866-6299
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