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  • 1
    Language: English
    In: Environmental management, December 2010, Vol.46(6), pp.878-93
    Description: This article presents several case studies in southwest Germany, which aimed to support land use management decisions by a process-oriented statistical upscaling of point-related environmental monitoring data to the landscape scale. When techniques of data subsetting were used in a sensible way and corresponding to the appropriate scale for the evaluation envisaged, multiple linear regression offered a data mining technique which was able to spatially predict relatively complex environmental patterns with parsimonious, interpretable and accurate models, whereby different evaluation scales were best represented by different DTM resolutions. Scenario models based upon the regression formulas were a valuable tool for visualizing management options and evaluating management impacts (tree species selection) on soil functions (carbon storage), which qualifies the presented methodology as a useful aid in decision making. Such upscaling techniques may be used for forecasting long-term effects of ecosystem management, but they provided no information on temporal dynamics. Therefore, time trends of point information on soil solution data were scaled by linking them to soil chemical data which was available in higher spatial resolution, using both statistical and process-oriented methods.
    Keywords: Conservation of Natural Resources ; Decision Support Techniques ; Environmental Monitoring -- Methods
    ISSN: 0364152X
    E-ISSN: 1432-1009
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  • 2
    Language: English
    In: Forest Ecology and Management, March 1, 2014, Vol.315, p.12(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.foreco.2013.12.015 Byline: Simon Boden, Hans-Peter Kahle, Klaus von Wilpert, Heinrich Spiecker Abstract: acents We described the temporal and spatial variation of Norway spruce tree-ring width. acents We assessed the response of tree-ring width to changes in moisture availability. acents Results indicated no short-term adaptive capacity to changing climate conditions. acents Results showed an enhancement of growth synchronicity among trees. acents Indicatives of a loss in growth resilience were found. Article History: Received 5 August 2013; Revised 9 December 2013; Accepted 14 December 2013
    ISSN: 0378-1127
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Ecological Modelling, 10 October 2016, Vol.337, pp.48-62
    Description: Accurate and reliable predictions of the future development of forest site productivity are crucial for the effective management of forest stands. Static models which simply extrapolate productivity into the future are inappropriate under conditions of environmental change since they lack a close link between fundamental environmental drivers and forest growth processes. Here we present a dynamic environment-sensitive site index model formulated in the framework of a nonlinear state space approach based on longitudinal data from long-term experimental plots. Estimation of the model parameters was carried out using the prediction error minimization method. Our aim was to identify dynamic relationships between site index and environmental variables and to make conditional predictions of the future development of site index under climate change scenarios. Nonlinear, interactive, as well as accumulative effects of environmental factors (climate/weather and nitrogen influx) on the growth response were considered in the model. In the study, we estimated the dynamic environment-sensitive site index model using data from 604 Norway spruce ( [L.] Karst.) long-term experimental plots in southwest Germany with measurement data covering a period of more than 100 years from the end of the 19th century until today. We used the calibrated model to project future site index changes under increasing growing season temperature scenarios. Conventional climate change impact studies usually utilize a gradient approach and apply space-for-time substitution for the parameterization of models that are calibrated using spatial variability in the data. In contrast, the approach presented here utilizes the longitudinal data structure of multiple real growth time series to simultaneously exploit spatial and temporal variation in the data to provide more reliable and robust projections. Limitations of the space-for-time substitution approach in forest growth modelling are discussed.
    Keywords: Norway Spruce ; Space-for-Time Substitution ; Nonlinear State Space Approach ; Longitudinal Data Structure ; Prediction Error Minimization Method ; Environmental Sciences ; Ecology
    ISSN: 0304-3800
    E-ISSN: 1872-7026
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  • 4
    Language: English
    In: Canadian journal of forest research =, 2013, Vol.44(1), pp.71-81
    Description: Fine-root distributions (FRDs) of forest stands are hypothesized to be a reflection of the influence of site properties on the intrinsic rooting strategies of trees. Based on forest soil survey data, we present a multivariate approach to identify the main parameters of FRD patterns of Central European forests, compare them with the FRD model according to Gale and Grigal (1987), and aim to detect the decisive site and soil properties. Two main parameters for the description of FRDs were found: one describes “shallowness” and the other additionally characterizes “divergence” from an evenly decreasing FRD with depth. With these two parameters, distinct FRD patterns could be described better than with absolute values of depth-dependent fine-root densities or with the compared FRD model. Comparing all sites, no significant differences occurred regarding stand types for most of the analysed fine-root parameters. Specific site and soil properties were seemingly more responsible for the expression of FRD. Results of multivariate analyses suggest that the shape of FRDs is mainly a reflection of the trees’ strategy to optimally adapt to the local soil physical and hydrological conditions. Soil chemical properties were of increased relevance when sites with either spruce or beech were analysed and for the prediction of uneven FRDs. The applied soil survey design enabled us to identify parameters, which can describe FRD patterns and how they are influenced by several soil and site properties in general. These multivariate relationships should be considered and discussed in the context of ecological forest models in further research. ; p. 71-81.
    Keywords: Forest Soils ; Forests ; Hydrology ; Rooting ; Fine Roots ; Fagus ; Prediction ; Models ; Soil Chemical Properties ; Multivariate Analysis ; Picea ; Soil Surveys ; Forest Stands ; Trees
    ISSN: 1208-6037
    ISSN: 00455067
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  • 5
    Language: English
    In: Journal of Plant Nutrition and Soil Science, April 2012, Vol.175(2), pp.221-235
    Description: The hydraulic properties of soils, their ability to store and conduct water, mainly govern the availability of soil water for plants. Information on the hydraulic properties is needed, for the quantification of drought risk at a given site. Furthermore, knowledge of the water transport is the precondition for the estimation of element fluxes in the soil, when predicting element leaching from the root zone to the groundwater. For forest soils, only few systematic investigations of their hydraulic properties exist. Within the 2nd forest‐soil survey of Germany, soil samples were taken along a regular 8 km × 8 km grid in the forests of the State of Baden‐Württemberg and the hydraulic properties were estimated in the laboratory by multistep outflow experiments. Besides the soil‐hydraulic measurements, numerous additional soil chemical and physical analyses were carried out and comprehensive profile descriptions were compiled and integrated in a hydraulic database. Based on this database, multiple‐linear‐regression techniques were used to develop pedotransfer functions for the water‐retention curve and the unsaturated‐hydraulic‐conductivity curve using the parametric models of Mualem/van‐Genuchten. Our work fills a gap since to our knowledge, no pedotransfer functions for the unsaturated hydraulic conductivity for forest soils exist so far. The predictive accuracy of the established pedotransfer functions, both for the water‐retention curve and the hydraulic‐conductivity curve, is in the range of (and in some cases better than) other published pedotransfer functions that were mostly derived for agricultural soils.
    Keywords: Water Retention ; Hydraulic Conductivity ; Forest Soils ; Pedotransfer Functions
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 6
    Language: English
    In: Journal of Plant Nutrition and Soil Science, June 2010, Vol.173(3), pp.380-390
    Description: One main problem with current research on spatio‐temporal modeling of ion fluxes in forest soils is the separation of space and time effects in the soil‐monitoring concept. This article describes an approach to overcome this weakness. Time trends of point information on soil‐solution data (base‐cation concentrations and fluxes) are scaled by linking them to soil‐chemical data which is available in higher spatial resolution and can be upscaled to an area base. This approach is based on a combined evaluation of bulk soil and soil‐solution data using both statistical and process‐oriented methods. Multiple‐linear‐regression analyses coupled with geostatistics were developed to predict spatial patterns of exchangeable cation percentages. In a second step, empirical ion‐distribution coefficients were adapted according to Gapon using data of suction‐cup plots and bulk‐soil samples. Seasonally adjusted time‐series data of soil‐solution chemistry were then connected with the maps of the predicted exchangeable‐cation percentages by means of the Gapon equations. This evaluation step provided both time‐ and space‐dependent maps of cation concentrations in the soil solution. Finally, using the results of a water‐budget model it was possible to derive spatio‐temporal patterns of soil cation fluxes. Methodological limitations and the results of verification processes are discussed. The methods described can only be used in acidic soils and should not be used in soil layers rich in humus, since adsorption to C compounds differs from adsorption to clay minerals. The time increments of the models should be not shorter than yearly in order to suppress annual periodicity. Although the Gapon equations were not based on laboratory‐determined exchange solutions at quasi‐equilibrium, but rather on field data from the suction‐cup technique, the exchangeable‐cation percentages showed steady functions of selectivity coefficients. The methods tested at a watershed scale may be flexible enough to be applied at other scales as well.
    Keywords: Regionalization ; Upscaling ; Gapon Equation ; Exchange Coefficient ; Forest Soils
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 7
    Language: English
    In: Environmental Monitoring and Assessment, 2011, Vol.174(1), pp.65-89
    Description: This study evaluates the acidification status and trends in streams of forested mountain ranges in Germany in consequence of reduced anthropogenic deposition since the mid 1980s. The analysis is based on water quality data for 86 long-term monitored streams in the Ore Mountains, the Bavarian Forest, the Fichtelgebirge, the Harz Mountains, the Spessart, the Black Forest, the Thuringian Forest, and the Rheinisches Schiefergebirge of Germany and the Vosges of France. Within the observation period, which starts for the individual streams between 1980 and 2001 and ends between 1990 and 2009, trends in chemical water quality were calculated with the Seasonal Mann Kendall Test. About 87% of the streams show significant ( p 〈 0.05) negative trends in sulfate. The general reduction in acid deposition resulted in increased pH values (significant for 66% of the streams) and subsequently decreased base cation concentrations in the stream water (for calcium significant in 58% and magnesium 49% of the streams). Reaction products of acidification such as aluminum (significant for 50%) or manganese (significant for 69%) also decreased. Nitrate (52% with significant decrease) and chloride (38% with significant increase) have less pronounced trends and more variable spatial patterns. For the quotient of acidification, which is the ratio of the sum of base cations and the sum of acid anions, no clear trend is observed: in 44% of the monitored streams values significantly decreased and in 23% values significantly increased. A notable observation is the increasing DOC concentration, which is significant for 55% of the observed streams.
    Keywords: Water quality ; Acidification ; Forested catchments ; Deposition ; Germany
    ISSN: 0167-6369
    E-ISSN: 1573-2959
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  • 8
    Language: English
    In: Journal of Plant Nutrition and Soil Science, February 2012, Vol.175(1), pp.24-33
    Description: Acidification and eutrophication of soils had been the main activators for the implementation of forest soil monitoring in Central Europe. Thus, field and lab studies focused on gathering information that is essential for the evaluation of the chemical status and its trend. A systematic assessment of soil physical threats caused by machine use in forests has not been integrated yet into the soil‐monitoring systems. In this study, a first approach to get a deeper insight into structure damages of forest topsoils was derived for 302 systematically distributed grid points in the Federal State of Baden‐Württemberg (SW Germany) during the nation‐wide soil survey performed from 2006 to 2008. We derived an approach to assess structure damage based on a key system using field information on structural and hydromorphic topsoil properties. It covers eight satellites surrounding the central monitoring soil pit at each grid point. Our survey focused on the mere stand area excluding visible damage and systematic skid trails. Analysis of structure‐damage intensity and spatial distribution leads to the conclusion that damage caused by vehicle traffic off the skid trails is a wide‐spread phenomena in Baden‐Württemberg forests, where wheeling is not restricted by steepness of terrain. Although regulations to control machine use recommending vehicle traffic to skid trails and fortified roads have been in place since the early 1980s, soil‐structure damages off these trails have reached significant levels. In the future, it will thus be indispensable to put more emphasis on the importance of soil‐protection aims in the ranking of the economic objectives of forest organizations and forest owners.
    Keywords: Forest Soil Monitoring ; Soil Structure ; Soil Deformation ; Mechanized Forest Operations
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 9
    Language: English
    In: Forest Ecology and Management, 2001, Vol.143(1), pp.27-37
    Description: In the Convent Forest case study, the measuring plots were stratified by the following first- and second-order structure units. First-order structures were classified as treefall gaps, regeneration areas, and closed stand areas, whereas second-order structures were defined by tree species and the density of the crown layer. The measurements were taken in an experimental watershed (9.3 ha) in a mixed-species stand consisting of European beech ( Fagus sylvatica L.), silver fir ( Abies alba Mill.) and Norway spruce ( Picea abies (L.) Karst.). Water fluxes were simulated by the one-dimensional Darcy model WHNSIM. The output was composed by the area-weighted sum of fluxes referring to the structural units. By this ‘structural approach’, we were able to demonstrate the spatial heterogeneity of canopy structures and tree species that cause a fine-scale patchwork of differing water and nutrient budgets. The different flux rates in the selected structural units were proved by statistical tools. The data generated with WHNSIM provided good estimates of soil-water fluxes that could then be linked with lysimeter concentration data. Evapotranspiration (ET) levels were within the range of values expected for this specific forest type. Crown density related ET differences appeared well-characterized. The simulation of the ecosystem output and its temporal structure can be improved by the following ‘structured’ modeling method: (1) dividing the ecosystem into representative structural units, (2) modeling these strata separately, and (3) putting the results together like a puzzle at the output end. Averaging the primary measured data resulted in a less sensitive shape of simulated streamflows. The results emphasize the importance of structural information for the recognition and prognostication of processes on the ecosystem level in forest stands.
    Keywords: Modeling ; Spatial Variability ; Mixed-Species Stand ; Nitrogen ; Water Yield ; Watershed ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 10
    Language: English
    In: Ecological Processes, 2014, Vol.3(1), pp.1-17
    Description: Abstract Introduction Conceptual hydrological models are useful tools to support catchment water management. However, the identifiability of parameters and structural uncertainties in conceptual rainfall-runoff modeling prove to be a difficult task. Here, we aim to evaluate the performance of a conceptual semi-distributed rainfall-runoff model, HBV-light, with emphasis on parameter identifiability, uncertainty, and model structural validity. Results The results of a regional sensitivity analysis (RSA) show that most of the model parameters are highly sensitive when runoff signatures or combinations of different objective functions are used. Results based on the generalized likelihood uncertainty estimation (GLUE) method further show that most of the model parameters are well constrained, showing higher parameter identifiability and lower model uncertainty when runoff signatures or combined objective functions are used. Finally, the dynamic identifiability analysis (DYNIA) shows different types of parameter behavior and reveals that model parameters have a higher identifiability in periods where they play a crucial role in representing the predicted runoff. Conclusions The HBV-light model is generally able to simulate the runoff in the Pailugou catchment with an acceptable accuracy. Model parameter sensitivity is largely dependent upon the objective function used for the model evaluation in the sensitivity analysis. More frequent runoff observations would substantially increase the knowledge on the rainfall-runoff transformation in the catchment and, specifically, improve the distinction of fast surface-near runoff and interflow components in their contribution to the total catchment runoff. Our results highlight the importance of identifying the periods when intensive monitoring is critical for deriving parameter values of reduced uncertainty.
    Keywords: Dynamic identifiability analysis ; HBV-light model ; Hydrological modeling ; Sensitivity analysis ; Uncertainty analysis
    E-ISSN: 2192-1709
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