Albrecht Gnauck

Assessing resilience in long-term ecological data sets

In this paper the concept of resilience is discussed on the base of 13 case studies from the German branch of the International Long-Term Ecological Research Program. In the introduction the resilience approach is presented as one possibility to describe ecosystem dynamics. The relations with the concepts of adaptability and ecological integrity are discussed and the research questions are formulated. The focal research objectives are related to the conditions of resilient behaviour of ecosystems, the role of spatio-temporal scales, the differences between short- or long-term dynamics, the basic methodological requirements to exactly define resilience, the role of the reference state and indicators and the suitability of resilience as a management concept. The main part of the paper consists of 13 small case study descriptions, which demonstrate phase transitions and resilient dynamics of several terrestrial and aquatic ecosystems at different time scales. In the discussion, some problems arising from the interpretation of the time series are highlighted and discussed. The topics of discussion are the conceptual challenges of the resilience approach, methodological problems, the role of indicator selection, the complex interactions between different disturbances, the significance of time scales and a comparison of the case studies. The article ends with a conclusion which focuses on the demand to link resilience with adaptability, in order to support the long-term dynamics of ecosystem development.

Water salinity investigation in the Sundarbans rivers in Bangladesh

Bangladesh, through its complex network of river systems, drains an area of about 1.76 million km 2 of the catchments of the Ganges, the Brahmaputra and the Meghna, of which only 7.5% lies in Bangladesh. The Sundarbans is situated in the Ganges catchment area, which is known as the single largest mangrove forest and unique ecosystem in the world. It has an area 6017 km 2 and a natural shield that protects the coastal area from storm surges and cyclones. It also plays a potential role in the regional economy and ecosystems. Since the diversion of Ganges water at Farakka Barrage in India from early 1975, as a result the water and soil salinity has penetrated. Consequently, both siltation and increased salinity have degraded water quality in the Sundarbans rivers, and threats for mangrove ecosystems. At present, ground water use in the study area is less because of high salinity intrusion. For salinity investigation, time series data for four years (13 rivers) were used for water salinity modelling. The objectives of this paper are to investigate the water salinity approximation in the Sundarbans rivers, which will be considered as a tool for decision making. It will make a contribution to develop an interdisciplinary management plan and to ensure that fresh water is supplied to the Sundarbans by the Ganges for the protection of mangrove ecosystems.

Theoretical Demands for Long-Term Ecological Research and the Management of Long-Term Data Sets

Long-term ecological studies are required to understand ecosystem complexity, to develop integrated dynamic models, and to explore appropriate measures for the assessment and control of ecosystem behaviour. The knowledge derived from long-term ecological studies should be a prerequisite to formulate ecosystem management plans, i.e. with reference to recent environmental processes. Long-term problems are especially interesting elements of ecosystem theory. Many hypotheses only can be tested for validity from a long-term aspect, and many generalized ideas about ecosystem development could not be verified satisfactory up to now due to a lack of long-term data sets. In this introductory statement chapter, some theoretical aspects of ecosystem dynamics are sketched. These outlines are used to derive demands and questions from ecosystem theory towards long-term ecological studies. The queries are posed referring to six main objectives of long-term research: (i) understanding large-scale variabilities, (ii) understanding the interactions of short-term and long-term fluctuations, (iii) understanding self-organization, (iv) understanding rare events and disturbances, (v) better understanding the impacts of anthropogenic use of landscape resources on ecosystem functions, and (vi) generation of knowledge and data for the development and evaluation of new generations of ecosystem models for resource management. These items can be taken to demonstrate the enormous research demands referring to long-term environmental dynamics and to develop and apply techniques of ecological statistics, data management, and ecosystem modelling.

The Role of Statistics for Long-Term Ecological Research

Sustainable management of natural resources requires a good understanding of ecosystems components and their interrelationships. Statistics is essential for understanding the structure and behaviour of ecological processes and provides the basis of predictive modelling. Mostly, physical, chemical, and biological variables are recorded across time and space. They serve as indicators, giving information concerning the state and changes of ecosystems. Most of monitored ecological indicators are non-stationary in time structure. The classical static statistical methods revealed the presence of trends and long memories in these data sets. On the other hand, modern dynamic statistical methods indicate the presence of long-term cycling processes. The Fourier polynomial is a technique for approximating periodic functions by sums of cosine and sine periodic functions, shifted and scaled. Therefore, it may be suitable for approximating cycling processes with a fixed frequency as portrayed by some ecological indicators. Wavelet analysis can be used to investigate the timescale behaviour of ecological processes. This analysis reveals the long-term evolution of an ecological indicator at different resolutions, the dominant scale of variability in the data set, and its correlation and cross-correlation with other ecological indicators on a scale by scale basis.

A Concept of a Virtual Research Environment for Long-Term Ecological Projects with Free and Open Source Software

The management of data and data resources created by different research activities are heavily influenced by various research philosophies and sampling strategies. Within long-term environmental research (LTER) projects data on flows of individuals, chemical substances and other biotic and abiotic materials are collected by different project partners and institutions. This leads not only to different data bases, but also to incomparable data sets. Therefore, a virtual research environment (VRE) for research projects concerning environmental management should be worked out. The facilities of data sharing, interactive data collaboration and data storage as well as the communication within a project team by metadata are in the focus of a VRE which have to be optimised by WEB 2.0 and other collaboration tools. From this background the FOSS application “GeoNetwork – Opensource” (GNOS) is aimed to be used as a central component for data management in a VRE.

Using a Commercial Optimisation Tool for Fine Tuning of Parameters of an Eutrophication Model

Simulation models are well-known informatic tools to manage environmental knowledge. Current approaches to ecosystems modelling are theoretically based on information theory, thermodynamics, topology, or systems theory. Water quality models are used for managing eutrophication problems. In the past, the Cottbus Eutrophication Simulator (CEUS) has been designed on the base of MATLAB and SIMULINK, which enables an user to couple the simulator with different software tools. To quantify these relations differential equations, some site constants and model specific parameters have to be specified. The fine tuning of parameters of an ecological model can be considered from the perspective of a suitable optimization procedure. Especially the commercial optimization software ISSOP realised different optimization algorithms which are traced back to one standard form of discrete optimization. In the paper, results of parameter optimisation will be presented for important water quality indicators. The results of parameter fine tuning and possibilities of parameter optimisation are discussed.

Fourier polynomial approximation of estuaries water salinity in the Sundarbans region of Bangladesh

The geographical location, characteristics of the coastal region and the monsoon climate render Bangladesh highly vulnerable to natural disasters. The reduction of upstream fresh water in the Ganges basin caused for high saline water penetration in the estuaries of the Sundarbans region. The five estuaries namely Baleswar, Bangra, Kunga, Malancha and Raimangal are highly affected by saline water intrusion and tidal inundation which is a new threat for estuaries ecosystems. The time series water salinity data were used for water salinity approximation. The estuaries water salinity modelling was done through Fourier polynomial approach using MATLAB software and GIS used for environmental data analysis and visualisation. Almost four estuaries water salinity has crossed the water salinity threshold line and the Baleswar estuary is in the marginal situation. The objective of this study is to understand the water salinity fluctuations and threatened ecosystems in the river estuaries of the Sundarbans mangrove region.

The Role of Ecosystem Modelling for Long-Term Ecological Research

Analysis, control, and management of ecosystems are complex tasks which have to cover broad ranges of operating environmental states and decision making. Current approaches to ecosystems modelling and simulation are mostly based on information theory, thermodynamics, topology, or balances of biological and chemical components. Ecosystems are considered from the point of view of information theory as complex dynamic communication networks with living and non-living components and their interrelationships. State space approaches are used for ecosystem management. But these models give no answer to structural ecosystem changes. The relational ecology approach covers more the structural problems of ecosystem modelling. The relationships are given qualitatively but cannot be quantified easily. The network approach seems to be the most appropriate approach to include behavioural and structural changes of ecosystems in models.

Invasive Species in the Sundarbans Coastal Zone (Bangladesh) in Times of Climate Change: Chances and Threats

The Sundarbans mangrove forests, wetlands and their native as well as invasive plant species are lying within the Bangladesh coastal region, which is gifted with vast natural resources, a delta, tidal flat, mangrove forests, marches, lagoons, bars, spilt, estuaries and coastal ecological environment. These habitats, biotopes and ecosystems also serve as habitat for especially four dominant tree species of the Sundarbans, the Sundri (Heritiera fomes), Gewa (Excoecaria agallocha), (Ceriops decandra) and (Sonneratia apetala). But the existence of these and many more native species is endangered. The Sundarbans species are threatened by various natural and anthropogenic pressures including climate change. So the native species are approximately decreasing significantly by the year 2100 due to sea level rise (88 cm) in the Sundarbans area compared to the year 2001.There 23 invasive species, which belong to 18 families and 23 genera. These species are highly invasive, six species are moderately invasive and the remaining are potentially invasive. From the 23 invasive species only four are exotic or alien. The disturbances may arrest succession at any stage and contribute to the biological invasion of invasive plants. The within these biodiversity hotspots and vast natural or coastal water resources lying potential for communities survival and 36.8 million dependent people are some of the strongly pending managing demands next to existing Natural World Heritage Sites’ already existing protective management support to be discussed in this chapter. As with the coastal natural resources drastically reduction due to unplanned use by community and stakeholders, also the Sundarbans mangrove forests, wetlands and their species are vastly affected through these developments and the most important observation for vulnerability aspects and maximum possible amplitudes is coming up, which has been investigated in within this research and chapter. Also the present situation stated that an integrated natural resource management plan is necessary for the protection of the mangrove coastal ecosystem.

Vulnerability of Mangrove Forests and Wetland Ecosystems in the Sundarbans Natural World Heritage Site (Bangladesh)

The Sundarbans Natural World Heritage Site is lying within the Bangladesh coastal region, which is gifted with vast natural resources, a delta, tidal flat, mangrove forests, marches, lagoons, bars, spilt, estuaries and coastal ecological environment. These habitats, biotopes and ecosystems also serve as potential resources for anthropogenic communities: 36.8 million people are living within the coastal region of Bangladesh and being dependent on coastal water resources, for which the Sundarbans Natural World Heritage Site is giving some protective management support. Nevertheless the natural coastal resources are drastically reducing due to unplanned use by the community and the stakeholders, although the Ganges-Brahmaputra-Meghna Rivers are carrying 6 million m3/s water. As a result, the Sundarbans mangrove forests and wetlands are vastly affected through these developments. The present situation demands that an integrated natural resource management plan is necessary for the protection of the mangrove coastal ecosystem. This chapter was prepared based on primary and secondary data sources, as the objectives were to analyze the present coastal mangrove natural resources management status. The study investigates the deltaic Sundarbans natural world heritage site with its mangrove forests and wetlands ecosystem development and management strategies to ensure less vulnerability and a sustainable development of coastal mangrove resources in the Ganges-Brahmaputra Rivers deltaic coastal floodplain region of Bangladesh.