Driving forces of landscape change - current and new directions   总被引：1，自引：0，他引：1  

Bürgi  Matthias  Hersperger  Anna M.  Schneeberger  Nina 《Landscape Ecology》2004,19(8):857-868

The concept of driving forces is gaining increasing attention in landscape-change research. We summarize the state of the art of this field and present new conceptual and methodological directions for the study of driving forces of landscape changes. These new directions address four major challenges faced by landscape-change studies, i.e., studying processes and not merely spatial patterns, extrapolating results in space and time, linking data of different qualities, and considering culture as a driver of landscape change. The proposed research directions include: studying landscape change across borders and transects, focusing on persistence as well as change, investigating rates of change, considering attractors of landscape change, targeting correlation and causality, and searching for precursors of landscape change. Based on established knowledge and the new approaches we outline a standard procedure to study driving forces of landscape change. We anticipate that our analytical and systematic approach increases the relevance of studies of landscape change for science as well as for the solution of real world problems.  相似文献   

Effective retention of litter-derived dissolved organic carbon in organic layers     

Matthias Müller  Frank Hagedorn 《Soil biology & biochemistry》2009,41(6):1066-1074

This study aimed to gain insight into the generation and fate of dissolved organic carbon (DOC) in organic layers. In a Free Air CO₂ Enrichment Experiment at the alpine treeline, we estimated the contribution of ¹³C-depleted recent plant C to DOC of mor-type organic layers. In an additional laboratory soil column study with 40 leaching cycles, we traced the fate of ¹³C-labelled litter-DOC (22 and 45 mg l⁻¹) in intact Oa horizons at 2 and 15 °C. Results of the field study showed that DOC in the Oa horizon at 5 cm depth contained only 20 ± 3% of less than six-year-old C, indicating minor contributions of throughfall, root exudates, and fresh litter to leached DOC. In the soil column experiment, there was a sustained DOC leaching from native soil organic matter. Less than 10% of totally added litter-DOC was leached despite a rapid breakthrough of a bromide tracer (50 ± 7% within two days). Biodegradation contributed only partly to the DOC removal with 18-30% of added litter-DOC being mineralized in the Oa horizons at 2 and 15 °C, respectively. This was substantially less than the potential 70%-biodegradability of the litter-DOC itself, which indicates a stabilization of litter-DOC in the Oa horizon. In summary, our results give evidence on an apparent ‘exchange’ of DOC in thick organic layers with litter-DOC being retained and ‘replaced’ by ‘older’ DOC leached from the large pool of indigenous soil organic matter.  相似文献   

Soil–atmosphere greenhouse gas exchange in a cool,temperate Eucalyptus delegatensis forest in south-eastern Australia     

Benedikt J. Fest  Stephen J. Livesley  Matthias Drösler  Eva van Gorsel  Stefan K. Arndt 《Agricultural and Forest Meteorology》2009,149(3-4):393-406

Forests are the largest C sink (vegetation and soil) in the terrestrial biosphere and may additionally provide an important soil methane (CH₄) sink, whilst producing little nitrous oxide (N₂O) when nutrients are tightly cycled. In this study, we determine the magnitude and spatial variation of soil–atmosphere N₂O, CH₄ and CO₂ exchange in a Eucalyptus delegatensis forest in New South Wales, Australia, and investigate how the magnitude of the fluxes depends on the presence of N₂-fixing tree species (Acacia dealbata), the proximity of creeks, and changing environmental conditions. Soil trace gas exchange was measured along replicated transects and in forest plots with and without presence of A. dealbata using static manual chambers and an automated trace gas measurement system for 2 weeks next to an eddy covariance tower measuring net ecosystem CO₂ exchange. CH₄ was taken up by the forest soil (?51.8 μg CH₄-C m^?2 h^?1) and was significantly correlated with relative saturation (S_r) of the soil. The soil within creek lines was a net CH₄ source (up to 33.5 μg CH₄-C m^?2 h^?1), whereas the wider forest soil was a CH₄ sink regardless of distance from the creek line. Soil N₂O emissions were small (<3.3 μg N₂O-N m^?2 h^?1) throughout the 2-week period, despite major rain and snowfall. Soil N₂O emissions only correlated with soil and air temperature. The presence of A. dealbata in the understorey had no influence on the magnitude of CH₄ uptake, N₂O emission or soil N parameters. N₂O production increased with increasing soil moisture (up to 50% S_r) in laboratory incubations and gross nitrification was negative or negligible as measured through ¹⁵N isotope pool dilution.The small N₂O emissions are probably due to the limited capacity for nitrification in this late successional forest soil with C:N ratios >20. Soil–atmosphere exchange of CO₂ was several orders of magnitude greater (88.8 mg CO₂-C m^?2 h^?1) than CH₄ and N₂O, and represented 43% of total ecosystem respiration. The forest was a net greenhouse gas sink (126.22 kg CO₂-equivalents ha^?1 d^?1) during the 2-week measurement period, of which soil CH₄ uptake contributed only 0.3% and N₂O emissions offset only 0.3%.  相似文献   

Spatiotemporal variations of soil surface roughness from in-situ laser scanning   总被引：1，自引：0，他引：1  

Sören-Nils Haubrock  Matthias Kuhnert  Sabine Chabrillat  Andreas Güntner  Hermann Kaufmann 《CATENA》2009

Microtopography and roughness are highly dynamic properties of the soil surface and important factors governing surface runoff and erosion processes. While various remote sensing technologies were successfully applied for topography measurements at different spatial scales, there is a lack of field studies that collected systematically microtopography data over long observation periods. In this paper an approach to measure and quantify surface roughness in the field based on laser scanning technologies is presented. Between June 2004 and November 2005 97 in-situ measurements were conducted in a test site with two different sandy substrates in vegetation-free conditions. Two-dimensional high-resolution (1 mm) datasets where generated for eight micro erosion plots of 0.25 to 2.9 m² in size. Dynamics and pattern formation were quantified for surface roughness and surface height changes. Roughness patterns at different scales were analyzed by local roughness indices using sliding windows of 3 to 55 mm in size. Results show strong spatial and temporal dynamics in surface roughness as well as substrate-specific variations. Temporal roughness variations could be detected and were linked to precipitation patterns. The methods presented in this paper are considered suitable to generate high-resolution datasets on spatiotemporal and multi-scale microtopography patterns and to advance the understanding of surface processes at small scales in natural environments.  相似文献   

Insignificant acute toxicity of TiO2 nanoparticles to willow trees     

Eva Mareike Seeger  Anders Baun  Matthias Kästner  Stefan Trapp 《Journal of Soils and Sediments》2009,9(1):46-53

Background, aim, and scope  

Manufactured nanoparticles (MNP) are expected to increase in production in near future. In response, their environmental fate and effects are intensively studied. Phytotoxicity of some types of nanoparticles has been observed for annual species in the seed germination and root elongation test. Yet, no results of toxicity tests with trees have been reported. Woody species, dominant in many ecosystems, may be vulnerable in particular due to the large porous wood compartment.  相似文献   

Maize root‐derived C in soil and the role of physical protection on its relative stability over shoot‐derived C     

Hui Xu  Bart Vandecasteele  Laura Zavattaro  Dario Sacco  Matthias Wendland  Pascal Boeckx  Geert Haesaert  Steven Sleutel 《European Journal of Soil Science》2019,70(5):935-946

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Immunolocalization of (1,4)-beta-galactan in tension wood fibers of poplar     

Arend M 《Tree physiology》2008,28(8):1263-1267

The occurrence and distribution of (1,4)-beta-galactan in wood cells of poplar (Populus trichocarpa Torr. & A. Gray x P. koreana Rehder) were studied by immunolabeling with a monoclonal antibody (LM5) specific to this carbohydrate epitope. Immunofluorescence microscopy revealed exclusive binding of the LM5 antibody to tension wood fibers, indicating the specific presence of (1,4)-beta-galactan in cell walls of this wood cell type. Higher magnifications achieved with the fluorescence microscope and additional immunogold electron microscopy showed that the binding of the LM5 antibody was mainly restricted to a narrow cell wall area between the gelatinous G-layer and the secondary cell wall. This labeling pattern strongly suggests a role of (1,4)-beta-galactan in cross-linking the G-layer and secondary cell wall. Furthermore, the exclusive localization of (1,4)-beta-galactan in tension wood strengthens the view that this carbohydrate epitope can be considered a highly specific marker of reaction wood formation in mechanically stressed trees.  相似文献   

Competitiveness in the global forest industry sector: an empirical study with special emphasis on Germany     

Matthias Dieter  Hermann Englert 《European Journal of Forest Research》2007,126(3):401-412

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Salicylatreiche Weiden für die Arzneimittelherstellung     

Nadja Förster  Christian Ulrichs  Matthias Zander  Ralf Kätzel  Inga Mewis 《Gesunde Pflanzen》2009,61(3-4):129-134

The use of salicylate rich willow bark is necessary for the economic fabrication of herbal drugs in the pharmaceutical industry. Natural derived salicylates can be used to medicate fever, rheumatic disturbances or headache. Clones from three willow species Salix daphnoides, Salix pentandra, and Salix purpurea were analysed for their salicylate content. All species showed a distinct salicylate profile. The major salicylate of S.?daphnoides and S.?purpurea was salicortin, whereas the main compound of S.?pentandra was 2′-O-acetylsalicortin. Clones of S.?daphnoides showed the highest mean salicylate content, followed by S.?purpurea and S.?pentandra. The variability within salicylates among species was higher than the clone variability. Also the seasonality of salicylates in willow bark was studied. The analysis revealed that after a peak concentration of salicylates in spring the content decreased during the vegatative season from March to August 2007. The lowest concentration was found August 2007. An increase of the salicylate concentration could be observed from August to October 2007. Specific clone selections and the determination of the optimal harvest time to gain highest salicylate contents are important for the economic fabrication of herbal drugs.  相似文献   

Does long-term farmyard manure fertilization affect short-term nitrogen mineralization from farmyard manure?   总被引：2，自引：0，他引：2  

Leif Nett  Sven Averesch  Silke Ruppel  Jörg Rühlmann  Carmen Feller  Eckhard George  Matthias Fink 《Biology and Fertility of Soils》2010,46(2):159-167

One of the challenges in organic farming systems is to match nitrogen (N) mineralization from organic fertilizers and crop demand for N. The mineralization rate of organic N is mainly determined by the chemical composition of the organic matter being decomposed and the activity of the soil microflora. It has been shown that long-term organic fertilization can affect soil microbial biomass (MB), the microbial community structure, and the activity of enzymes involved in the decomposition of organic matter, but whether this has an impact on short-term N mineralization from recently applied organic substances is not yet clear. Here, we sampled soils from a long-term field experiment, which had either not been fertilized, or fertilized with 30 or 60 t ha⁻¹ year⁻¹ of farmyard manure (FYM) since 1989. These soil samples were used in a 10-week pot experiment with or without addition of FYM before starting (recent fertilization). At the start and end of this experiment, soil MB, microbial basal respiration, total plant N, and mineral soil N content were measured, and a simplified N balance was calculated. Although the different treatments used in the long-term experiment induced significant differences in soil MB, as well as total soil C and N contents, the total N mineralization from FYM was not significantly affected by soil fertilization history. The amount of N released from FYM and not immobilized by soil microflora was about twice as high in the soil that had been fertilized with 60 t ha⁻¹ year⁻¹ of FYM as compared with the non-fertilized soil (p < 0.05).  相似文献