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  • 1
    Language: English
    Description: A growing interest in using forest biomass for bioenergy generation may stimulate intensive harvesting scenarios in Germany. We calculated and compared nutrient exports of conventional stem only (SO), whole tree without needles (WT excl. needles), and whole tree (WT) harvesting in two medium aged Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) stands differing in productivity, and related them to soil nutrient pools and fluxes at the study sites. We established allometric biomass functions for each aboveground tree compartment and analyzed their nutrient contents. We analyzed soil nutrient stocks, estimated weathering rates, and obtained deposition and seepage data from nearby Level II stations. WT (excl. needles) and WT treatments cause nutrient losses 1.5 to 3.6 times higher than SO, while the biomass gain is only 1.18 to 1.25 in case of WT (excl. needles) and 1.28 to 1.30 in case of WT in the pine and spruce stand, respectively. Within the investigated 25-year period, WT harvesting would cause exports of N, K+, Ca2+, and Mg2+ of 6.6, 8.8, 5.4, and 0.8 kg·ha−1 in the pine stand and 13.9, 7.0, 10.6, and 1.8 kg·ha−1 in the spruce stand annually. The relative impact of WT and WT (excl. needles) on the nutrient balance is similar in the pine and spruce stands, despite differences in stand productivities, and thus the absolute amount of nutrients removed. In addition to the impact of intensive harvesting, both sites are characterized by high seepage losses of base cations, further impairing the nutrient budget. While intensive biomass extraction causes detrimental effects on many key soil ecological properties, our calculations may serve to implement measures to improve the nutrient balance in forested ecosystems.
    Keywords: Info:Eu-Repo/Classification/Ddc/630 ; Ddc:630 ; Fichte ; Kiefer ; Ausdünnung ; Oberirdische Biomasse ; Energetische Nutzung ; Standwachstum ; Nährstoffgehalt ; Nährstoffansammlung ; Tu Dresden ; Publikationsfonds ; Spruce ; Pine ; Thinning ; Aboveground Biomass ; Energetic Use ; Stand Growth ; Nutrient Contents ; Nutrient Accumulation ; Tu Dresden ; Publishing Funds
    Source: Networked Digital Library of Theses and Dissertations
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  • 2
    Dissertation
    Dissertation
    Molecular Diversity Preservation International (MDPI)
    Language: English
    Description: The transport of nutrients in forest soils predominantly occurs along preferential flow pathways (PFP). This study investigated the composition of phosphorus (P) forms in PFPs and soil matrix in several temperate beech forests with contrasting soil P contents in Germany. The PFPs were visualized using dye tracer experiments. Stained and unstained soil was sampled from three profile cuts per plot and analyzed for P fractions. The results show that labile P concentrations were highest in the O-layer and had the same range of values at all sites (240–320 mg·kg−1), although total P (TP) differed considerably (530–2330 mg·kg−1). The ratio of labile P to TP was significantly lower in the P-rich soil compared to the medium and P-poor soils. By contrast, the ratio of moderately labile P to TP was highest at the P-rich site. The shifts in P fractions with soil depth were generally gradual in the P-rich soil, but more abrupt at the others. The contents of labile and moderately labile P clearly differed in PFPs compared to soil matrix, but not statistically significant. The studied soils are characterized by high stone contents with low potential for P sorption. However, indications were found that labile organically bound P accumulates in PFPs such as biopores.
    Keywords: Info:Eu-Repo/Classification/Ddc/630 ; Ddc:630 ; Phosphorfraktionen ; Waldboden ; Vorzugsstrom ; Pfp ; Tu Dresden ; Publikationsfonds ; Phosphorus Fractions ; Forest Soil ; Preferential Flow ; Pfp ; Tu Dresden ; Publishing Fund
    Source: Networked Digital Library of Theses and Dissertations
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  • 3
    Language: English
    Description: Phosphorus (P) export from forest soils is mainly driven by storm events, which induce rapid flow processes by preferential flow bypassing large parts of the soil matrix. However, little is known about the dynamics, magnitude, and driving processes of P exports into surface waters. In this paper, we present the results of a monitoring study in a small forested catchment (21 ha) situated in the low mountain ranges of Saxony, Germany. During the fixed schedule-sampling (weekly to bi-weekly sampling frequency for a three-year period), a mean total-P concentration of 8 μg·L−1 was measured. However, concentrations increased up to 203 μg·L−1 during individual storm flow events. Based on the analyzed concentrations and continuously measured discharge we calculated mean annual export rates of 19 to 44 g·ha−1·a−1 for the weekly sampling frequency with different load calculation methods. If events are included into the annual load calculation, the mean annual export fluxes can be up to 83 g·ha−1·a−1 based on the different load calculation methods. Predictions of total-P export rates based on a sampling strategy which does not consider short-term changes due to factors such as storms will substantially underestimate P exports.
    Keywords: Info:Eu-Repo/Classification/Ddc/630 ; Ddc:630 ; Bewaldete Einzugsgebiete ; Phosphorexporte ; Lastberechnungen ; Technische Universität Dresden ; Publikationsfond ; Forested Catchments ; Phosphorus Exports ; Load Calculations ; Technische Universität Dresden ; Publishung Fund
    Source: Networked Digital Library of Theses and Dissertations
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  • 4
    Language: English
    Description: A major argument for incorporating deciduous tree species in coniferous forest stands is their role in the amelioration and stabilisation of biogeochemical cycles. Current forest management strategies in central Europe aim to increase the area of mixed stands. In order to formulate statements about the ecological effects of mixtures, studies at the stand level are necessary. In a mixed stand of Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) in the Ore Mountains (Saxony, Germany), the effects of these two tree species on chemical and microbial parameters in the topsoil were studied at one site in the form of a case study. Samples were taken from the O layer and A horizon in areas of the stand influenced by either birch, spruce or a mixture of birch and spruce. The microbial biomass, basal respiration, metabolic quotient, pH-value and the C and N contents and stocks were analysed in the horizons Of, Oh and A. Significantly higher contents of microbial N were observed in the Of and Oh horizons in the birch and in the spruce-birch strata than in the stratum containing only spruce. The same was found with respect to pH-values in the Of horizon and basal respiration in the Oh horizon. Compared to the spruce stratum, in the birch and spruce-birch strata, significantly lower values were found for the contents of organic C and total N in the A horizon. The findings of the case study indicated that single birch trees have significant effects on the chemical and microbial topsoil properties in spruce-dominated stands. Therefore, the admixture of birch in spruce stands may distinctly affect nutrient cycling and may also be relevant for soil carbon sequestration. Further studies of these functional aspects are recommended.
    Keywords: Info:Eu-Repo/Classification/Ddc/630 ; Ddc:630 ; Info:Eu-Repo/Classification/Ddc/640 ; Ddc:640 ; Info:Eu-Repo/Classification/Ddc/690 ; Ddc:690 ; Birke ; Fichte ; Baumarten ; Ph-Wert ; Bodenatmung ; Humus ; Tu Dresden ; Publikationsfonds ; Birch ; Spruce ; Tree Species Effects ; Ph-Value ; Soil Respiration ; Humus ; Topsoil ; Technical University Dresden ; Publication Funds
    Source: Networked Digital Library of Theses and Dissertations
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  • 5
    Language: English
    Description: Land use change and climate variability are the main drivers of watershed hydrological processes. The main objective of this study was to assess the impact of land use change and climate variability on hydrology of the Mara River Basin in East Africa. Land use maps generated from satellite images were analyzed using the intensity analysis approach to determine the patterns, dynamics and intensity of land use change. Changes in measured streamflow caused separately by land use change and climate variability were separated using the catchment water-energy budget based approach of Budyko framework. The information on past impact of climate variability on streamflow was used to develop a runoff sensitivity equation which was then used to predict the future impact of climate change on streamflow. Finally, the impact of agroforestry on watershed water balance was predicted using SWAT (Soil and Water Assessment Tool) model. Deforestation and expansion of agriculture were found to be dominant and intensive land use changes in the watershed. The deforestation was attributed to illegal encroachment and excision of the forest reserve. The deforested land was mainly converted to small scale agriculture particularly in the headwaters of the watershed. There was intensive conversion of rangeland to largescale mechanized agriculture which accelerated with change of land tenure (privatization). The watershed has a very dynamic land use change as depicted by swap change (simultaneous equal loss and gains of a particular land use/cover) which accounted for more than half of the overall change. This implies that reporting only net change in land use (of MRB) underestimates the total land use change. The results show that streamflow of Nyangores River (a headwater tributary of the Mara River) significantly increased over the last 50 years. Land use change (particularly deforestation) contributed 97.5% of change in streamflow while the rest of the change (2.5%) was caused by climate variability. It was predicted that climate change would cause a moderate 15% increase in streamflow in the next 50 years. SWAT model simulations suggested that implementation of agroforestry in the watershed would reduce surface runoff, mainly due expected improvement of soil infiltration. Baseflow and total water yield would also decrease while evapotranspiration would increase. The changes in baseflow (reduction) and evapotranspiration (increase) were attributed to increased water extraction from the soil and groundwater by trees in agroforestry systems. The impact of agroforestry on water balance (surface runoff, baseflow, water yield and evapotranspiration) was proportional to increase in size of the watershed simulated with agroforestry. Modelling results also suggested that climate variability within the watershed has a profound effect on the change of water balance caused by implementation of agroforestry. It is recommended that authorities should pay more attention to land use change as the main driver of change in watershed hydrology of the basin. More effort should be focused on prevention of further deforestation and agroforestry may be considered as a practical management strategy to reverse/reduce degradation on the deforested parts of the watershed currently under intensive cultivation.
    Keywords: 333.91
    Source: The British Library
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  • 6
    Language: English
    Description: The objective of this study was to analyze patterns, dynamics and processes of land-use/cover changes in the transboundary Mara River Basin in East Africa. We specifically focused on deforestation and expansion of agriculture in the watershed. The intensity analysis approach was used to analyze data from satellite imagery-derived land-use/cover maps. Results indicate that swap change accounted for more than 50% of the overall change, which shows a very dynamic landscape transformation. Transition from closed forest to open forest was found to be a dominant landscape change, as opposed to a random change. Similarly, transition from open forest to small-scale agriculture was also found to be a dominant transition. This suggests a trend (pathway) of deforestation from closed forest to small-scale agriculture, with open forest as a transitional land cover. The observed deforestation may be attributed to continuous encroachment and a series of excisions of the forest reserve. Transition from rangeland to mechanized agriculture was found to be a dominant land-use change, which was attributed to change in land tenure. These findings are crucial for designing strategies and integrated watershed management policies to arrest further deforestation in the forest reserves as well as to sustainably control expansion of agriculture.
    Keywords: Info:Eu-Repo/Classification/Ddc/630 ; Ddc:630 ; Landnutzungsänderung ; Intensitätsanalyse ; Systematischer Übergang ; Entwaldung ; Tu Dresden ; Publikationsfond ; Land-Use Change ; Intensity Analysis ; Systematic Transition ; Deforestation ; Tu Dresden ; Publishing Fund
    Source: Networked Digital Library of Theses and Dissertations
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  • 7
    Language: English
    Description: Study region Nyangores River watershed, headwater catchment of Mara River basin in Kenya. Study focus Climate variability and human activities are the main drivers of change of watershed hydrology. The contribution of climate variability and land use change to change in streamflow of Nyangores River, was investigated. Mann Kendall and sequential Mann Kendall tests were used to investigate the presence and breakpoint of a trend in discharge data (1965–2007) respectively. The Budyko framework was used to separate the respective contribution of drivers to change in discharge. Future response of the watershed to climate change was predicted using the runoff sensitivity equation developed. New hydrological insights for the region There was a significant increasing trend in the discharge with a breakpoint in 1977. Land use change was found to be the main driver of change in discharge accounting for 97.5% of the change. Climate variability only caused a net increase of the remaining 2.5% of the change; which was caused by counter impacts on discharge of increase in rainfall (increased discharge by 24%) and increase in potential evapotranspiration (decreased discharge by 21.5%). Climate change was predicted to cause a moderate 16% and 15% increase in streamflow in the next 20 and 50 years respectively. Change in discharge was specifically attributed to deforestation at the headwaters of the watershed.
    Keywords: Info:Eu-Repo/Classification/Ddc/690 ; Ddc:690 ; Klimavariabilität ; Landnutzungsänderung ; Hydrologie ; Streamflow ; Wassersicherheit ; Budyko Rahmen ; Technische Universität Dresden ; Publikationsfonds ; Climate Variability ; Land Use Change ; Hydrology ; Streamflow ; Water Security ; Budyko Framework ; Technische Universität Dresden ; Publishing Fund
    Source: Networked Digital Library of Theses and Dissertations
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  • 8
    Language: English
    Description: A major argument for incorporating deciduous tree species in coniferous forest stands is their role in the amelioration and stabilisation of biogeochemical cycles. Current forest management strategies in central Europe aim to increase the area of mixed stands. In order to formulate statements about the ecological effects of mixtures, studies at the stand level are necessary. In a mixed stand of Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) in the Ore Mountains (Saxony, Germany), the effects of these two tree species on chemical and microbial parameters in the topsoil were studied at one site in the form of a case study. Samples were taken from the O layer and A horizon in areas of the stand influenced by either birch, spruce or a mixture of birch and spruce. The microbial biomass, basal respiration, metabolic quotient, pH-value and the C and N contents and stocks were analysed in the horizons Of, Oh and A. Significantly higher contents of microbial N were observed in the Of and Oh horizons in the birch and in the spruce-birch strata than in the stratum containing only spruce. The same was found with respect to pH-values in the Of horizon and basal respiration in the Oh horizon. Compared to the spruce stratum, in the birch and spruce-birch strata, significantly lower values were found for the contents of organic C and total N in the A horizon. The findings of the case study indicated that single birch trees have significant effects on the chemical and microbial topsoil properties in spruce-dominated stands. Therefore, the admixture of birch in spruce stands may distinctly affect nutrient cycling and may also be relevant for soil carbon sequestration. Further studies of these functional aspects are recommended.
    Keywords: Birke ; Fichte ; Baumarten Effekte ; Ph Wert ; Bodenatmung ; Humus ; Mutterboden ; Tu Dresden ; Publikationsfonds ; Birch ; Spruce ; Tree Species Effects ; Ph-Value ; Soil Respiration ; Humus ; Topsoil ; Technical University Dresden ; Publication Funds
    Source: Networked Digital Library of Theses and Dissertations
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  • 9
    Dissertation
    Dissertation
    Freiburg i.Br.: Inst. f. Bodenkunde u. Waldernährungslehre, Univ.
    Language: German
    Description: Mit engl. u. frz. Zsfassung ; Thesis (doctoral)--Albert-Ludwigs-Universität Freiburg im Breisgau, 1986 ; 253 S.,10 S. Anh
    Source: Center for Research Libraries
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  • 10
    Language: English
    Description: A growing interest in using forest biomass for bioenergy generation may stimulate intensive harvesting scenarios in Germany. We calculated and compared nutrient exports of conventional stem only (SO), whole tree without needles (WT excl. needles), and whole tree (WT) harvesting in two medium aged Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) stands differing in productivity, and related them to soil nutrient pools and fluxes at the study sites. We established allometric biomass functions for each aboveground tree compartment and analyzed their nutrient contents. We analyzed soil nutrient stocks, estimated weathering rates, and obtained deposition and seepage data from nearby Level II stations. WT (excl. needles) and WT treatments cause nutrient losses 1.5 to 3.6 times higher than SO, while the biomass gain is only 1.18 to 1.25 in case of WT (excl. needles) and 1.28 to 1.30 in case of WT in the pine and spruce stand, respectively. Within the investigated 25-year period, WT harvesting would cause exports of N, K+, Ca2+, and Mg2+ of 6.6, 8.8, 5.4, and 0.8 kg·ha−1 in the pine stand and 13.9, 7.0, 10.6, and 1.8 kg·ha−1 in the spruce stand annually. The relative impact of WT and WT (excl. needles) on the nutrient balance is similar in the pine and spruce stands, despite differences in stand productivities, and thus the absolute amount of nutrients removed. In addition to the impact of intensive harvesting, both sites are characterized by high seepage losses of base cations, further impairing the nutrient budget. While intensive biomass extraction causes detrimental effects on many key soil ecological properties, our calculations may serve to implement measures to improve the nutrient balance in forested ecosystems.
    Keywords: Fichte ; Kiefer ; Ausdünnung ; Oberirdische Biomasse ; Energetische Nutzung ; Standwachstum ; Nährstoffgehalt ; Nährstoffansammlung ; Tu Dresden ; Publikationsfonds ; Spruce ; Pine ; Thinning ; Aboveground Biomass ; Energetic Use ; Stand Growth ; Nutrient Contents ; Nutrient Accumulation ; Tu Dresden ; Publishing Funds ; Ddc:630 ; Rvk:Za 16000
    Source: Networked Digital Library of Theses and Dissertations
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