365 research outputs found
Environmental filtering versus Natural variation and plant strategies: key components of plant trait modulation by nutrient supply
No full textAerts, M.A.P.A. [Promotor]Witte, J.P.M. [Promotor]Bodegom, P.M. van [Copromotor
Putting assembly rules to work: predicting vegetation distribution through plant traits
No full textAerts, M.A.P.A. [Promotor]Witte, J.P.M. [Promotor]Bodegom, P.M. van [Copromotor
Remote Sensing of Vegetation Characteristics in Support of Ecological Modelling
No full textWitte, J.P.M. [Promotor]Bodegom, P.M. van [Copromotor]Kooistra, L. [Copromotor
Evaporation from dry dune vegetation
No full textWitte, J.P.M. [Promotor]Zee, S.E.A.T.M. van der [Promotor]Bartholomeus, R.P. [Copromotor
National water management and the value of nature
No full textIn order to attune its water management to the demands of nature, the Dutch Government uses the ecohydrological DEMNAT for the analysis of scenarios. The input to this model consists of changes in hydrological variables that may be computed with present hydrological models. The output consists of changes in the botanical quality of various ecosystem types, and of resulting values for nature conservation. The applied ecosystem types are defined on the basis of abiotic factors that determine the plant species composition of a vegetation. In the Netherlands these are: salinity, moisture regime, nutrient availability, acidity. Water management measures may cause changes in these four factors and, as a result, change the species composition of a vegetation.Species of the Dutch flora are allotted to the ecosystem types. It is questioned whether the resulting ecological groups are appropriate for describing the plant cover of the Netherlands with the aid of FLORBASE. This national database contains data, per kilometer square, on the presence of indigenous plant species. To answer the question, a comparison is made with a division of species into phytosociological groups by the Dutch standard work of Westhoff & Den Held (1969). On the basis of a correlation analysis, it is concluded that the ecological groups are of better use for the analysis of the national plant cover than the phytosociological groups.The ecological species groups are used in combination with FLORBASE to make nation-wide maps of ecosystem types. On the basis of both the number and the indicative value of diagnostic species, the botanical quality of each kilometer square is assessed for each ecosystem map. The boundaries of the quality classes are obtained by expert judgement. It is possible, however, to compute class boundaries with a mathematical procedure, also for grid cells larger than 1 km 2. The maps are corrected for regional differences in the intensity of the plant inventories.It is argued that the conservation value of classification units - such as species and ecosystem types - is especially related to the criterion 'rarity'. The measuring of rarity is discussed and a mathematical formula is presented for the valuation of classification units. Eight methods for the botanical valuation of areas are compared. Those methods which are based on species richness and species conservation values yield results that experts find unsatisfactory. The most favored method, however, is based on the quality classes of the ecosystem maps in combination with the conservation values of the ecosystem types.</p
Climate-proof and process-based relationships between water, oxygen and vegetation
No full textWitte, J.P.M. [Promotor]Aerts, M.A.P.A. [Promotor]Bodegom, P.M. van [Copromotor]Dam, J.C. van [Copromotor
Keeping an eye on reliability: The organizational requirements of future renewable energy systems
No full textThe reliable operation of energy infrastructures is more than just a technical matter. It is also dependent upon the organizational structure that enables and constrains entities in their management of operations. Yet this lesson seems forgotten in our planning of future renewable energy systems. There, focus is on technical development, market deployment, and supporting government policies. Much less attention has been given to the broader organizational requirements necessary to ensure their reliable operation once they are put in place. This research proposes a framework to pinpoint the organizational structures required for the reliable operation of future renewable energy infrastructures. To this end it analyses the complex relationship between technology and organization in energy systems and seeks ways to express the technological characteristics of energy systems in terms of their organizational requirements in a simple yet effective manner. The result is a stepwise progression that moves from several critical technical functions and their control mechanisms to the responsibilities and roles that they imply for the entities involved in their operation (i.e. the who does what, when, and how, and the nature of coordination between them), and finally to the organizational structure that may facilitate the latter. The proposed framework is illustrated on the transition to the use of hydrogen as a motor fuel in the Netherlands as depicted by the European Union’s HyWays project. It shows how different technical characteristics of the hydrogen networks envisioned in 2020, 2035, and 2050 require different organizational structures to facilitate reliable operations. In addition, it discusses the implications of neglecting the organizational dimension of reliability in the development of renewable energy systems, such as organizational lock-ins and path dependencies.Economics of InfrastructuresTechnology, Policy and Managemen
Spectrum Trading in the United Kingdom: Considering Market-Based Liberalization from Two Perspectives
No full textThis thesis considers the policy of liberalization via spectrum trading in the U.K. through the lenses of two perspectives on markets. The central research question of this thesis is: How is the outcome of the policy of liberalization via spectrum trading in the U.K. considered through the lenses of two perspectives on markets: the MO and MT approach? The MO approach (Market as objective) is the first perspective considered and it implies that an efficient resource allocation in spectrum will result from the introduction of markets. In the second perspective the market is used to facilitate rather than replace spectrum administration. This perspective is referred to as the market as tool approach (the MT approach). The thesis explores the difference in these two approaches, the relationship between them and the implications of taking one approach over the other.Economics of InfrastructuresTechnology, Policy and Managemen
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