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51.
Dr Uwe Schindler Joerg Steidl Lothar Mueller 《Archives of Agronomy and Soil Science》2013,59(1):63-73
Abstract The influence of regional soil distribution and land use on discharge formation in the “Stettiner Haff” catchment (8,456 km2) was investigated. The model ABIMO was used to calculate mean discharge for a long period (1961 – 1990) in consideration of regional differences in hydrological site conditions and soil heterogeneity. The highest discharge was found on settlement areas (276 mm a?1), on devastated plots (319 mm a?1) and on the non-hydromorphic agriculturally used sandy soils (214 mm a?1). Due to their small size these sub-areas were found to influence regional discharge for a limited extent only. On loam and clay soils only about 100 mm a?1 of discharge was formed. However, this share proved to be most important for the height of regional discharge because of the high area proportion in the region. Mineral soils of comparable parent material produce lower discharge under hydromorphic conditions than under non-hydromorphic conditions. With increasing clay content of the soils these differences decreased. The agriculturally used areas were found to be most important for the region's water discharge. They accounted for 83% of the discharge, i.e. they originated 119 mm a?1 on average. At forest sites, the discharge height was about 52 mm a?1. Sites close to groundwater table (groundwater level <1 m) proved to act as depletive areas. 相似文献
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Impact of land‐use intensity on the relationships between vegetation indices,photosynthesis and biomass of intensively and extensively managed grassland fens 下载免费PDF全文
C. M. H. Metzger J. Heinichen T. Eickenscheidt M. Drösler 《Grass and Forage Science》2017,72(1):50-63
Vegetation indices are widely used as model inputs and for non‐destructive estimation of biomass and photosynthesis, but there have been few validation studies of the underlying relationships. To test their applicability on temperate fens and the impact of management intensity, we investigated the relationships between normalized difference vegetation index (NDVI), leaf area index (LAI), brown and green above‐ground biomass and photosynthesis potential (PP). Only the linear relationship between NDVI and PP was management independent (R2 = 0·53). LAI to PP was described by a site‐specific and negative logarithmic function (R2 = 0·07–0·68). The hyperbolic relationship of LAI versus NDVI showed a high residual standard error (s.e.) of 1·71–1·84 and differed between extensive and intensive meadows. Biomass and LAI correlated poorly (R2 = 0·30), with high species‐specific variability. Intensive meadows had a higher ratio of LAI to biomass than extensive grasslands. The fraction of green to total biomass versus NDVI showed considerable noise (s.e. = 0·13). These relationships were relatively weak compared with results from other ecosystems. A likely explanation could be the high amount of standing litter, which was unevenly distributed within the vegetation canopy depending on the season and on the timing of cutting events. Our results show there is high uncertainty in the application of the relationships on temperate fen meadows. For reliable estimations, management intensity needs to be taken into account and several direct measurements throughout the year are required for site‐specific correction of the relationships, especially under extensive management. Using NDVI instead of LAI could reduce uncertainty in photosynthesis models. 相似文献
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Bon Dr. Jul Rekler 《European Journal of Forest Research》1861,5(1):41-53
Ohne Zusammenfassung 相似文献
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Casparus J. BRINK Anneke POSTMA Etienne SLABBERT Ferdinand POSTMA A. Muthama MUASYA Karin JACOBS 《土壤圈》2020,30(6):778-790
Aspalathus linearis is a commercially important plant species endemic to the Cape Floristic Region of South Africa and is used to produce a herbal tea known as rooibos tea. Symbiotic interactions between A. linearis and soil bacteria play an important role in the survival of Aspalathus plants in the highly nutrient-poor, acidic fynbos soil. The aim of this study was to characterize and compare rhizosphere and bulk soil bacterial communities associated with natural and commercially grown A. linearis, as well as the effect of seasonal changes on these communities. Bacterial communities were characterized using high throughput amplicon sequencing, and their correlations with soil chemical properties were investigated. The N-fixing bacterial community was characterized using terminal restriction fragment length polymorphism and real time quantitative polymerase chain reaction. Actinobacteria, Proteobacteria, and Acidobacteria were the most dominant bacterial phyla detected in this study. Highly similar bacterial communities were associated with natural and commercially grown plants. Significant differences in the bacterial community were observed between rhizosphere and bulk soils collected in the dry season, while no significant differences were detected in the wet season. This study provides insights into bacterial community structure and potential factors shaping bacterial community structure with commercially important A. linearis. 相似文献
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Köhler H Gyra H Zimmer K Dräger KG Burkert B Lemser B Hausleithner D Cubler K Klawonn W Hess RG 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2001,48(3):185-195
After immunization of four calves with a live modified Mycobacterium paratuberculosis vaccine the course of the humoral and cell mediated immune reactions was studied during a 2-year clinical investigation. Furthermore, the possibility of shedding of the vaccine strain and the influence of the vaccination on the tuberculin skin test was determined. In addition to standard procedures recently developed diagnostic methods (antibody enzyme-linked immunosorbent assay, interferon-gamma test, polymerase chain reaction) were used. A cell-mediated immune reaction, reflected in an increased, specifically induced, interferon-gamma production developed much earlier (1-2 weeks post-immunization) than humoral immunity (8-16 weeks post-gamma immunization). While the increase in antibody titres was transient, declining to extremely low levels 48-60 weeks post-immunization, cell-mediated immunity remained detectable until the end of the investigation. Spread of the vaccine strain into the body and shedding were never detected during the whole course of the study except for one colon site in one calf. As late as 2 years after vaccine application positive or doubtful skin reactions against M. bovis purified protein derivative were measured, reflecting possible interference of the immunization with the diagnosis of bovine tuberculosis. At the end of the investigation, a positive cell-mediated immune reaction was detected the control animal although clinical, pathological and bacteriological examinations gave no indication for a mycobacterial infection. 相似文献