FG Bodenschutz und Rekultivierung
Refine
Document Type
- Conference publication not peer-reviewed (24) (remove)
Keywords
- Biological soil crusts (1)
- Hydroxides (1)
- Phosphorus (1)
- Sorption (1)
- biocrusts, photosynthesis, carbon (1)
- biological soil crusts (1)
- ecohydrology (1)
- ecosystem development (1)
- forests (1)
- metabolic activity (1)
Institute
BTU
Exploring hydrological and ecological processes plays a key role in understanding ecosystem development. In this respect, the constructed catchment, Chicken Creek (Hühnerwasser), has been established to promote fundamental and interdisciplinary scientific research. Since 2005, an on-going monitoring program has been established in this catchment to measure hydrological, biological, meteorological, and pedological parameters during the ecological development of the site. This comprehensive and multidisciplinary monitoring program has produced a large and diverse data set. Managing and exploring such a complex data set for research purposes can be a cumbersome task. As a consequence, we developed an online data portal https://www.b-tu.de/chicken-creek/apps/datenportal/ to efficiently handle the data from Chicken Creek catchment. The portal was constructed using R programming language, Shiny package, and the accompanying local Linux server. This platform allows for efficient data discovery, download, visualization, and analysis. Data visualizations are freely available, while data storage is limited to the authorized users. In comparison with the commonly used data base tools, R-Shiny offers several advantages. As an open source package, this platform allows for constructing a web data platform in an interactive way taking into account the complexity and diversity of the data. The flexibility of this routine enables to make an efficient user-demand data portal rather than relying on predetermined outputs. It also offers flexibility in data handling by using many different R packages, rendering versatile and extensive functionalities. R-Shiny is particularly powerful in terms of statistical analyses. Although the Chicken Creek online data portal is complete and available, new features, and extended capabilities are under active development. The Chicken Creek data portal provides a comprehensive and reliable database to give scientists a fast and easy access to all collected data.
Consequently, R-Shiny offers a great potential for future development of the web-based data portals to efficiently handle scientific data collected at different scales.
After completion of the construction in 2005 (Gerwin et al. 2009), a major challenge was to develop and install a cross-disciplinary long-term monitoring program for the 6 ha area to record major environmental parameters adapted to the development of the site (Schaaf et al. 2013).
During its first 15 years, Chicken Creek showed a very dynamic development (Elmer et al 2013). Whereas the abiotic geosystem of the first 2-3 years was characterized by heavy erosion and sediment transport, primary succession by invading vegetation and the unexpected formation of soil crusts within few years resulted in more biotic-abiotic feedbacks that controlled catchment hydrology. Our observations over a period of 15 years indicate that even minor variations in initial substrate characteristics (e.g. texture) can have lasting impacts on geomorphical, hydrological and biological development like erosion intensity, groundwater levels or establishment of vegetation patterns. The time-series of monitoring data combined with a structure model of the catchment (Gerke et al. 2013) allowed the closure of the water balance by relatively simple calculations of water storage volumes and the estimation of evapotranspiration (Schaaf et al. 2017). From these data three stages of ecosystem development were derived which are characterized by increasing influence of biota and increasing system complexity.
Due to disturbances of soils after open-cast lignite mining activities in the Lusatian mining district, Northeast Germany, large areas covered with excavated and dumped material. These initial soils are characterized by a lack of nutrients and organic matter which is why Robinia pseudoacacia was established during reclamation of those marginal sites. As a pioneer species, Robinia is well suitable for the establishment on reclaimed forest ecosystems due to the N fixation capability and its ability to grow on a nutrient-poor sandy substrate with low water holding capacity. Since the N requirement of the Robinia can be covered by symbiotic nodule bacteria, P is important as a growth-limiting nutrient. Even though the total and available P in soils increased with the age of the plantings (planted between 1995 and 2007), the ratio of available to total P decreased relative to younger plantings. Despite the accumulation of organic matter and the decomposition of organic bound P, the bioavailability is affected by ad- and desorption processes, especially on Fe- and Al-hydroxides. It was hypothesized that the P demand of young trees, initially provided by a one-time fertilizer application, exceeds the P supply by mineralization over time. As a first step, kinetics of P desorption from synthetic Fe- and Al-hydroxides were characterized by using humic acid as a model organic compound, to detect fast and slow releasable P over time. At the Robinia sites, soil samples were examined at different depth with regard to their C, N and P concentrations. From the first results, we can conclude that the P availability and its limitation influences the growth performance of Robinia as well as the N-fixing symbiotic bacteria and, thus, the C:N:P ratio as a long-term effect on an ecosystem scale.
In many ecosystems of the earth, biocrusts influence the successive development of vegetation through their influence on the soil formation. This change in soil structure, e.g. due to the accumulation of organic material and the ability of biological nitrogen fixation, results in significant feedback and controls of ecosystem processes, especially in arid regions. In Brandenburg, located in NE Germany, the dry grasslands on sand dunes and the post-mining landscapes, characterized by edaphic drought and lack of nutrients as well as disturbances, are ecologically interesting locations for investigations of the biocrusts. In recent years, the species composition, structure, N-fixation, C-fluxes, and accumulation as well as their soil hydrological properties of biocrusts have been characterized and ecophysiological measurements of biocrust activity and CO2 exchange of different biocrust types under standardized environmental conditions have been performed in the laboratory. These ecophysiological measurements were correlated for the first time with NDVI measurements using a modified consumer camera, thus enabling a spatial analysis of the photosynthesis hotspots and a transfer from the lab into the landscape. The development and physiological activity of biocrusts are significantly influenced by microclimatic boundary conditions and moisture-dry cycles. The duration of these moisture phases is decisive for their spatial and temporal development and for the differentiation of the developmental stages. The permanent recording of moisture in the biocrusts in the uppermost millimeters using a newly developed biocrust wetness sensor in combination with NDVI measurements enable detailed information about biocrust activities and carbon fluxes. These continuous measurements of NDVI and physiological activity with PRI sensors allows determining seasonal activity phases in relation to microclimatological site conditions. More recent technological developments in sensor technology make it possible to carry out detailed and cost-effective investigations of the biocrust activity over the course of the year.
Biological soil crusts (biocrusts) play an important role as pioneering organisms on initial soils and in open landscapes after natural and human disturbances. Even though they only cover the topsoil, biocrusts are key drivers for biogeochemical and ecological processes and influencing ecosystem development. Microclimatic conditions, texture, water holding capacity, and chemical soil properties lead to the formation of spatial patterns. Sandy nutrient-poor soils in pine forests in the open-cast lignite mining district in Brandenburg are covered by biocrust, dominated by different functional types and species (e.g. algae, mosses, lichens). The photosynthetic activity of these poikilohydric organisms, strongly depending on moisture, affects biocrust function and their impact on soil C pools and dynamics. Therefore, the evaluation of photosynthesis in relation to the spatial distribution pattern variation is fundamental. For this purpose, we combined different remote sensing techniques, spectral reflectance sensors, and chlorophyll fluorescence imaging to analyze the photosynthetic dynamics in relation to biocrust species composition and wetness. Desiccation of the biocrusts was detected with a miniature moisture sensor and related to their activity. A low-cost consumer grade camera was used to determine NDVI and to map the distribution and heterogeneity of chlorophyll for a comprehensive characterization of spatial photosynthetic activity pattern. Basic as well as maximum fluorescence, the maximum photochemical efficiency, and NDVI decreased during desiccation of the biocrusts, whereby moss and moss/lichen biocrusts showed higher water holding capacities relative to green algae biocrusts. The combination of different sensor technologies is a powerful tool for monitoring long-term biocrust development and their implication for soil C dynamics.
Ecosystems are characterized by high complexity and are dynamically changing by abiotic and biotic drivers such as climate, vegetation and soil fauna. Due to feedback processes between compartments, ecosystems show an inherent degree of locally heterogeneous properties and structures at multiple spatial and temporal scales.
The constructed catchment “Chicken Creek” represents a unique and outstanding site to study an ecosystem at the initial stage of development. The catchment is located about 20 km south of the city of Cottbus (Germany). The 6-ha catchment area was built in 2005 of coarse-textured quaternary sediments from the adjacent lignite mine and forms a back- and foot-slope that flattens out to a pond. A clay liner of 2-3 m thickness seals the catchment at the bottom, allowing for the formation of a local water body fed by precipitation. After construction the site was left to an unrestricted and unmanaged succession to elucidate the role of structures und processes during the initial establishment of an ecosystem. To study processes of ecosystem development and newly emerging structures the Chicken Creek catchment is equipped with a comprehensive ecological monitoring network. A network of more than 40 wells and two weirs allow for recording groundwater levels, surface runoff and discharge. Meteorological parameters are recorded at three weather stations. Annual aerial photos and vegetation monitoring reveal the floral colonisation of the area. Here, we present the 12 years of diverse and extensive monitoring program which has been launched to measure hydrological, biological, meteorological, and pedological parameters during the ecological development of the catchment area.
Top soils in temperate climates are regularly covered by cryptogames. Depending on the climatic and environmental conditions and their development stage, these biocrusts are built up by different species of cyanobacteria, bacteria, green algae, mosses, liverworts, lichens and fungi, which crosslink the uppermost soil particles. Biocrusts create a thin surface layer of high biotic activity, with high C and nutrient pools and fluxes to deeper soil layers, where the soil tends to be biotically and biogeochemically less active. Changes in soil structure, e.g. due to the accumulation of organic material and the ability of biological nitrogen fixation, result in significant feedback and control of biogeochemical processes. We analysed the response of photosynthesis and respiration to changing temperature and light in two moss-and lichen-dominated soil crusts from a dry acid grassland in the vicinity of a pine forest in Brandenburg, Germany. For the estimation of carbon fluxes, we combined lab-based CO2 gas exchange measurements and continuous determination of biocrust drying and rewetting cycles under field conditions. These experiments facilitated the development of an empirical photosynthesis model that allows for an estimation of the carbon dynamics of biological soil crusts based on their ecophysiological performance.
The Huehnerwasser catchment was constructed 2004-2005 in a post-mining landscape in Eastern Germany and was left for an unmanaged primary ecosystem succession. At the same time a comprehensive monitoring program was launched for observing the expected dynamic development of this 6 ha site. During the following years this artificially created system was subject to a series of fast changes with regard to morphology, hydrology or vegetation cover. In summary, these processes resulted in significant alterations of the original, initial system within a short period of time. This development can be divided up into single phases with dominating processes or groups of processes. A first phase was mainly characterized by interactions between abiotic system components such as water and substrate. However, already in this very early developmental phase biotic components in the form of microorganisms were a crucial system forming factor by means of biological soil crusts. This period was quickly replaced by a second phase with dominating hydrological processes. During this phase the local groundwater body of the system developed to its full extent. With the beginning of the present phase biota gained control of the system behavior. Particularly plants and related processes such as water uptake and evapotranspiration are now responsible for new modifications of the system. The Huehnerwasser site offers an example of young and highly dynamic ecological systems. This transitional development of a very young ecosystem contrasts with the behavior of mature ecosystems with slow and less pronounced changes unless the system is disturbed. In this paper we present insights into a unique landscape observatory which illustrates the dynamic nature of natural systems in fast motion.
ln 2005, a 7-ha artificial watershed (Hühnerwasser) was built an a post mined Iandscape in Lusatia, Germany from sandy Substrates of Pleistocene origin, commonly used in reclamation. The watershed was developed to investigate the initial phase of soil and ecosystem development under natural conditions. At this early stage, nutrients in young sandy soils are limited and pioneer plants become key components of natural succession. Local abundant pioneering legumes Lotus corniculatus and Trifolium arvense and one pioneer grass species Calamagrostis epigeios were investigated 5 years after watershed construction. ln the present study, we investigated the influence of spatial root distribution of these species an soil nitrogen accumulation and on nutrient redistribution. Soil, including roots, was sampled from field monoliths covered with the aforementioned plant species. Root systems of both legumes were mainly restricted to the upper 20 cm of soil, whereas roots of C. epigeios also developed strongly at greater depths. A positive relationship was found, with higher plant densities associated with higher root densities, which were related with higher nodule densities for legumes and which were all associated with significantly higher soil nitrogen concentration relative to non-vegetated areas.
This research provides rare information on the role root systems of pioneer legumes play in soil nitrogen input and development of nutrient patterns in the early stage of soil and ecosystem development during revegetation by natural succession.