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- Kurzumtriebsplantage (2)
- ecosystem development (2)
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- Energieholzanbau (1)
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The objective of this paper is to present observations, results from monitoring measurements, and preliminary conclusions about the development of patterns and structures during the first 5 years of development of an artificial catchment starting from point zero. We discuss the high relevance of initial system traits and external events for the system development and draw conclusions for further research. These investigations as part of a Collaborative Research Center, aim to disentangle and understand the feedback mechanisms and interrelationships of processes and their co-development with spatial and temporal structures and patterns by studying an initial, probably less complex ecosystem. Therefore, intensive measurements were carried out in the catchment with regard to the development of surface structures, hydrological patterns, vegetation dynamics, water chemistry, and element budgets. During the first 5 years, considerable changes within the catchment were observed. Both internal and external factors could be identified as driving forces for the formation of structures and patterns in the artificial catchment. Initial structures formed by the construction process and initial substrate characteristics were decisive for the distribution and flow of water. External factors like episodic events triggered erosion and dissection during this initial phase, promoted by the low vegetation cover, and the unconsolidated sandy substrate. The transformation of the initial geosystem into areas with evolving terrestrial or aquatic characteristics and from a very episodic to a more permanent stream network and discharge, together with the observed vegetation dynamics increased site diversity and heterogeneity with respect to water and nutrient availability and transformation processes compared with the more homogenous conditions at point zero. The processes and feedback mechanisms in the initial development of a new landscape may deviate in rates, intensity, and dominance from those known from mature ecosystems. It is therefore crucial to understand these early phases of ecosystem development and to disentangle the increasingly complex interactions between the evolving terrestrial and aquatic, biotic, and abiotic compartments of the system. Long-term monitoring of initial ecosystems may provide important data and parameters on processes and the crucial role of spatial and temporal structures and patterns to solve these problems. Artificially created catchments could be a suitable tool to study these initial developments at the landscape scale under known, designed, and defined boundary conditions.
Iron-cyanide (Fe-CN) complexes have been detected at Manufactured Gas Plant sites (MGP) worldwide. The risk of groundwater contamination depends mainly on the dissolution of ferric ferrocyanide. In order to design effective reme- diation strategies, it is relevant to understand the contaminant’s fate and transport in soil, and to quantify and mathe- matically model a release rate. The release of iron-cyanide complexes from four contaminated soils, originating from the former MGP in Cottbus, has been studied by using a column experiment. Results indicated that long-term cyanide (CN) release is governed by two phases: one readily dissolved and one strongly fixed. Different isotherm and kinetic equations were used to investigate the driving mechanisms for the ferric ferrocyanide release. Applying the isotherm equations assumed an approach by which two phases were separate in time, whereas the multiple first order equation considered simultaneous occurrence of both cyanide pools. Results indicated varying CN release rates according to the phase and soil. According to isotherm and kinetic models, the long-term iron cyanide release from the MGP soils is a complex phenomenon driven by various mechanisms parallely involving desorption, diffusion and transport processes. Phase I (rapid release) is presumably mainly constrained by the transport process of readily dissolved iron-cyanide complexes combined with desorption of CN bound to reactive heterogeneous surfaces that are in direct contact with the aqueous phase (outer-sphere complexation). Phase II (limited rate) is presumably driven by the diffusion controlled processes involving dissolution of precipitated ferric ferrocyanide from the mineral or inner-sphere complexation of fer- ricyanides. CN release rates in phase I and II were mainly influenced by the pH, organic matter (OM) and the total CN content. The cyanide release rates increased with increasing pH, decreased with low initial CN concentration and were retarded by the increase in OM content.
Relationships between substrate, surface characteristics, and vegetation in an initial ecosystem
(2013)
We investigated surface and vegetation dynamics in the artificial initial ecosystem “Chicken Creek” (Lusatia, Germany) in the years 2006–2011 across a wide spectrum of empirical data. We scrutinized three overarching hypotheses concerning (1) the relations between initial geomorphological and substrate characteristics with surface structure and terrain properties, (2) the effects of the latter on the occurrence of grouped plant species, and (3) vegetation density effects on terrain surface change. Our data comprise and conflate annual vegetation monitoring results, biennial terrestrial laser scans (starting in 2008), annual groundwater levels, and initially measured soil characteristics. The empirical evidence mostly confirms the hypotheses,
revealing statistically significant relations for several goal variables: (1) the surface structure properties, local rill density, local relief energy and terrain surface height change; (2) the cover of different plant groups (annual, herbaceous, grass-like, woody, Fabaceae), and local vegetation
height; and (3) terrain surface height change showed significant time-dependent relations with a variable that proxies local plant biomass. Additionally, period specific effects (like a calendar-year optimum effect for the occurrence of Fabaceae) were proven. Further and beyond the hypotheses, our findings on the spatiotemporal dynamics during the system’s early development grasp processes which generally mark the transition from a geo-hydro-system towards a bio-geo-hydro system (weakening geomorphology effects on substrate surface dynamics, while vegetation effects intensify with time), where pure geomorphology or substrate feedbacks are changing into vegetation–substrate feedback processes.
Mit dieser Arbeit wurde der Einfluss von biologischen Bodenkrusten auf die Benetzungshemmung / Hydrophobizität auf sandigen, anthropogen geschütteten, rekultivierten Böden der Tagebaufolgelandschaft und auf sandigen, sich mehr oder weniger natürlich entwickelnden Böden in Flugsandarealen und Dünengebieten Südbrandenburgs untersucht. Gezeigt wurde, dass sich in der Bergbaufolgelandschaft auf dem sandigen anthropogen geschütteten Substrat andere Krustenarten auf der Substratoberfläche ansiedeln als auf der Substratoberfläche von Flugsandgebieten und Dünen. Der Effekt der Benetzungshemmung ist bei den Krustenarten der rekultivierten Bergbauflächen stärker ausgeprägt als bei den natürlichen Flugsandgebieten und Dünen, wo die Benetzungshemmung im Krustentstadium mit Einfluss von Moosen wieder zurückgeht. Gerade Flechten haben in Bergbaufolgelandschaften negativen Einfluss auf die Infiltration von Niederschlag. Auch die Bindungskräfte zwischen den Partikeln spielen bei der Betrachtung des Einflusses der Benetzungshemmung / Hydrophobizität eine Rolle, denn es zeigt sich bei Betrachtung der Korngrößenverteilung, dass das Substrat in den Rekultivierungsgebieten der Bergbaufolgelandschaft unsortiert ist und hohe Anteile an Feinmaterial (Schluff und Ton) aufweisen kann. Auf den Flugsandgebieten findet eine natürliche
Sortierung der Partikel durch Wind und Wasser statt, wobei das Substrat meist locker lagernd vorkommt und lediglich im Lee von höheren Pflanzen zur Ruhe kommen kann. Dort übernehmen dann biologische Bodenkrusten und andere Mikroorganismen die Bindung und Festigung der Partikel z. B. durch extrazelluläre polymere Substanzen. Es wurde deutlich, dass die Akkumulation organischer Substanz bei Bewuchs mit Laubgehölzen in größerem Maße stattfindet als bei Bewuchs mit Nadelgehölzen. Jedoch weisen die Chlorophyll a-Gehalte auf mehr Biomasse durch biologische Bodenkrusten bei den Nadelgehölzen hin. Insgesamt ist festzuhalten, dass jeder untersuchte Standort separat für sich betrachtet werden muss und nicht von einer Chronosequenz im Sinne einer eindeutig zeitlichen Abfolge bei Betrachtung der Alter der Standorte ausgegangen werden kann. Lediglich die Standorte in der Bergbaufolgelandschaftfür sich sowie die Standorte in den relativ natürlich entwickelten Flugsand- und Dünengebieten können gemeinsam betrachtet werden. Wie gezeigt wurde, beeinflussen biologische Bodenkrusten gerade schon in der Initialphase der Bodenbildung den Wasserhaushalt durch Porenverschluss, durch hydrophob wirkende Exsudate,
aber auch durch Rhizoide der Moose, insbesondere im brandenburgischen Übergangsklima vom maritimen zum kontinentalen Klima. Durch die Regulierung des Wasserhaushalts des Bodens durch die biologischen Bodenkrusten wird die Bodenentwicklung in bestimmte Richtungen gelenkt. Hierfür sind allerdings Langzeitbeobachtungen und eine möglichst gewissenhafte Auswahl an Chronosequenzen notwendig.
Der Agrarholzanbau stellt allgemein eine sehr extensive Form der landwirtschaftlichen Flächennutzung dar. So können beispielsweise die Winderosion
oder der Stoffaustrag in das Grundwasser durch den Anbau von Bäumen auf ackerbaulich genutzten Standorten deutlich reduziert werden. Durch die Kombination von Bäumen und konventionellen Ackerfrüchten (Agroforstwirtschaft) können auch angrenzende Feldfruchtbereiche und somit der gesamte Ackerschlag von diesen positiven Effekten des Agrarholzanbaus profitieren. Im Rahmen dieser Studie wurde beispielhaft untersucht, ob und inwieweit der streifenförmige Anbau (Alley-Cropping) von im Kurzumtrieb bewirtschaftetem Agrarholz einerseits zu einer Verbesserung des Windschutzes und andererseits zu einer Erhöhung der Grundwasserqualität beitragen kann.
Robinia pseudoacacia L. is a pioneer tree species native from North America. Its original range is a climatic region classified as humid to sub-humid, with a mean annual precipitation of 1020 to 1830 mm. However, it grows under a wide range of edaphic and climatic conditions and the species has proven to be relatively drought tolerant. In central Europe, with a continental climate, the species has been successfully cropped for biomass production also on marginal land, even in post-‐mining areas characterized by water limitation and harsh edaphic conditions. Due its drought tolerance, fast resprouting rate and its ability to live in symbiosis with Rhizobia and thus fix atmospheric nitrogen, black locust could become a key species for short-‐rotation plantation on marginal land. Several studies have been already carried out to quantify the black locust above ground production and its water use efficiency. However, the relation between the black locust biomass allocation, root system development and plant water use has still to be examined. In our study we evaluated the drought stress effect on black locust below ground biomass production, root distribution, and the root and rhizobial association. Different irrigation regimes were chosen to test the plant’s performance in a lysimeter experiment, under semi-‐controlled environmental conditions, for the duration of two vegetation periods. From the results obtained we determined the root biomass allocation under different irrigation regimes and identified the close relation between the soil water condition and the rhizobial association.
There is a growing global need to produce more energy and reducing greenhouse gas emissions. One possible source of renewable energy in parts of Europe is the use of crop for bioenergy production. Currently, maize dominates the biogas production. For a diversified production of substrates alternative crops needs to be evaluated for their sustainable utilization and ecological integration into agro-systems. The new bioenergy plants IGNISCUM Candy and IGNISCUM Basic are cultivars of the Sakhalin Knotweed (Fallopia sachalinensis, Fam. Polygonaceae), which are characterized by a high annual biomass production. Information on the crop production of this species is rare. Hence, understanding plant response to the combinations of water and nutrients availability is crucial for the development of sustainable plant production. In greenhouse experiments we investigate the interrelations between nutrient supply, biomass production, and plant ecophysiology. For the determination of yield-transpiration relations at whole plant level we used a wick lysimeter system, which allows us to study plant growth under controlled water regimes and to calculate the plant transpiration. The irrigation is supplied by an automatic drip irrigation system and computer-controlled in relation to the volumetric soil water content. Four different water treatments associated to the SWC range from well-watered to drought stressed plants. The influence of plant sizes on plant water use was investigated under different nitrogen supply. The fertilizer applied is calcium ammonium nitrate (N) and the rates for the four treatments are 0, 50, 100, 150 kg N/ha at the beginning of the growing season. Plant transpiration is calculated on the basis of water input, storage and drainage in weekly intervals. The cumulative transpiration of the plants during the growing season is between 49 L (drought stressed) and 141 L (well-watered) per plant, respectively. We calculated a transpiration coefficient of 525 Liters per kg dry biomass.
The dynamics of dissolved organic carbon (DOC) have been intensively studied in mature ecosystems, but little is known about DOC dynamics and the significance of DOC as a substrate for microbial activity in early-successional catchments. We determined the concentration, chemical composition, radiocarbon age, and bioavailability of DOC along the hydrological flow path from soil solution to a downstream pond in a recently constructed catchment (Chicken Creek Catchment, Germany). Soil solution, upwelling ground water, subsurface water in an alluvial fan, and pond water all had high DOC concentrations (averaged 6.0 – 11.6 mg DOC L‐1), despite small carbon stocks in either vegetation or soil of the catchment. The mean 14C age of DOC in upwelling ground water was 2600 to 2800 years. Solid-state CPMAS 13C NMR revealed a higher proportion of aromatic compounds (32%) and a lower proportion of carbohydrates (33%) in upwelling ground water compared to pond water (18% and 45%, respectively). 14C age and 13C NMR spectra suggest that DOC was partly mobilized from charred organic matter inherent in the Quaternary substrate. In a 70-days incubation experiment, 20% of the total DOC was found to be bioavailable, irrespective of the water type. Origin of the microbial communities within the catchment (enriched from soil, stream sediment or pond water) had only marginal effects on overall DOC utilization. Overall, our data suggest that both recent and old DOC support microbial activity during early ecosystem succession, although a large fraction of the DOC is recalcitrant and eventually exported from the catchment once it has been mobilized.