FG Bodenschutz und Rekultivierung
The constructed catchment Chicken Creek was established in 2005 as an experimental landscape laboratory for ecosystem research. The 6 ha area with clearly defined horizontal as well as vertical boundary conditions was left for an unrestricted primary succession. The developing ecosystem offers the opportunity to study most processes occurring at the interface of bio-, pedo-, geo- and hydrosphere. Particularly interactions and feedbacks between different evolving compartments as well as the establishment of ecosystem functions and services can be investigated during the ongoing ecosystem development. The catchment is extensively instrumented since 2005 in order to detect transition stages of the ecosystem. Comprehensive data recorded with a high spatial and temporal resolution include hydrological, geomorphological, pedological, limnological as well as biological parameters.
This site offers the unique situation of an early stage ecosystem with highly dynamic system properties. The first years of development were characterized by a fast formation of geomorphological structures due to massive erosion processes at the initially non-vegetated surface. Hydrological processes led to the establishment of a local groundwater body within 5 years. In the following years the influence of biological structures like vegetation patterns gained an increasing importance. Feedbacks between developing vegetation and e.g. hydrological features became more and more dominant. As a result, different phases of ecosystem development could be distinguished until now.
This observatory offers manifold possibilities to identify and disentangle complex interactions between ecosystem compartments in situ under natural conditions. The originally low complexity of the system is growing with time facilitating the identification of influences of newly developing structures on ecosystem functions. Thus, it is possible to study effects of small-scale processes on the whole system at the landscape scale. In addition, the highly dynamic initial system properties allow the observation of multifaceted changes of ecosystem properties and functions within short periods of time.
The constructed catchment Chicken Creek was established in 2005 as an experimental landscape laboratory for ecosystem research. The 6 ha area with clearly defined horizontal as well as vertical boundary conditions was left for natural primary succession. All Critical Zone elements are represented at this site, which allows the study of most processes occurring at the interface of bio-, pedo-, geo- and hydrosphere. It provides outstanding opportunities for investigating interactions and feedbacks between different co-evolving compartments. The catchment has been extensively instrumented since 2005. Data are recorded with a high spatial and temporal resolution and include hydrological, geomorphological, pedological, limnological as well as biological parameters in order to detect transition states of the ecosystem. In contrast to other Critical Zone Observatories, this site offers the unique situation of an early stage ecosystem with highly dynamic properties. The first years of development were characterized by a fast formation of geomorphological structures due to massive erosion of the initially non-vegetated surface. Hydrological processes led to the establishment of a local groundwater body within 5 years. In the following years the influence of biological structures like vegetation patterns gained increasing importance. Feedbacks between developing vegetation and e.g. hydrological features became more and more apparent. As a result, different phases of ecosystem development have been distinguished.
Differences in soil P among silvopasture, grassland, and arable lands have been well established. Nevertheless, most of the reports compare soil properties under long-term sites. Thus, there exists little information on the effect of the conversion of silvopasture to arable or grassland use on soil P pools. The objective of the study was to determine the impact of converting silvopasture system (SP) into arable cropping and grassland system on the distribution of P pools and potential P bioavailability. We compared the following systems: SP system, SP converted to arable cropland (SP-AL), SP converted to grassland (SP-GL), and for comparative purposes, a long-term arable cropland (AL). The P fractionation was performed by a sequential extraction scheme, using acid and alkaline extractants on samples collected from the 0–10 and 10–20 cm soil layers. It was assumed that the large variations in soil-P fractionations are caused by the different management practices associated with land conversion. The results of P fractionation showed a dominance of calcium-bound P, HCl-extractable Pi constituted up to 36% of the soil total P (TP). However, the type of land use did not affect this P fraction. On the other hand, the reduction in labile-Pi and NaOH-Pi fractions observed at the SP-AL site may have led to the decline in readily available P. The soil total organic P (TPo) content was 8% and 17% lower at SP-AL compared to SP and SP-GL site, respectively. Labile organic-P (labile-Po) content was markedly higher at SP site compared to arable soils, and was ≈ 10% of TPo. The NaOH-Po constituted the highest fraction of the organic-P pool (55%–79% of TPo) across all the study systems, and was positively correlated with TPo (p < 0.01). The study indicates that conversion of SP system in temperate regions to arable cropping with conventional tillage seems to result in the reduction of P availability compared to SP, indicating SP as an important land-use practice.
Cross-linked polyacrylates in post-mining substrates: persistence and effects on plant growth
(2014)
Application of hydrophilic polymers composed of cross-linked polyacrylate can improve soil water-holding capacity and accelerate the restoration of post-mining substrates. In this work, we studied the persistence of a polyacrylate polymer incorporated into a soil and its impact on plant nutrients at a reclamation site of former lignite mining in Lusatia (Germany). In contrast to autumn application, the incorporation of the polymer enhanced the sequestration of plant-derived carbon in the soil, which was reflected by a significant increase in the concentration of a lignin marker. Attenuated total reflexion–Fourier transform infrared spectra (ATR-FTIR) and total elemental contents in the applied polymer suggested an intensive cation exchange between the polymer framework and the soil-forming substrate. In addition, there was an enrichment of carbonaceous material, which seems to reduce the swelling and thus the water-holding capacity of the cross-linked polyacrylate. Conversely, this process protected the polymer structure from rapid decomposition.
Ecosystems in transition: interactions and feedbacks with an amphasis on the initial development
(2014)
In this Special Issue of Biogeosciences on “Ecosystems in transition: Interactions and feedbacks with an emphasis on the initial development”, we bring together research on ecosystems undergoing state transitions, including artificially created and naturally formed sites, most of them in an initial
stage of development. State transitions of an ecosystem may occur either when a formerly stable system state is disturbed or when a developing system gradually achieves new functions during succession. This special issue presents a collection of observational and experimental studies that focus on processes occurring during state transitions in the development of ecosystems and provide insights into the feedback mechanisms controlling
them. These state transitions are studied at multiple scales, ranging from the pore scale to the catchment scale. The contributions
collected in this issue can be divided into two main groups: (i) studies dealing with state transition occurring in initial ecosystems without active human interference, and (ii) studies dealing with active restoration of ecosystems after severe disturbances.