Frank van der Meulen

Impact of grazing and atmospheric nitrogen deposition on the vegetation of dry coastal dune grasslands.

. A five-year experimental study was carried out to examine the combined effects of grazing and atmospheric nitrogen deposition on the vegetation of three dry dune grasslands: one short species-rich, one short species-poor, and one predominated by tall graminoids. Additional fertilization with nitrogen had no significant effect, neither in grazed nor in non-grazed plots. Exclusion of grazing by rabbits resulted in an increase in the frequency of perennial graminoids and a decrease in the frequency of annual graminoids and herbs. Nevertheless, species diversity remained the same in the species-rich grassland. During the experiment, the above-ground biomass increased in all nongrazed plots and the amount of bare soil and mosses decreased. The vegetation changes occurred mainly within one year after the exclusion of grazing. An exception is the grass-dominated site where the amount of Calamagrostis epigejos increased gradually from ca. 20 % in the first two years to about 50 % in the fourth and fifth year. Grazing by rabbits seems essential to prevent graminoids to become predominant in the dry dunes. If graminoids are dominant, grazing by horses can be an appropriate method to restore the original grassland vegetation. After six months of grazing by horses the grass-dominated site showed a decrease of the frequency of perennial graminoids, from 95 % to 80 %, and an increase of the frequency of perennial herbs, from 2.5 % to between 13 and 20 %.

Optimum-transformation of plant species cover-abundance values

Most of the methods used in the multivariate analysis of data on vegetation and environment, or transformations implied in such methods, put disproportionate emphasis on species with a relatively wide ecological amplitude occurring with relatively high cover-abundance values, and/or rare species. This problem can be overcome to some extent by reducing the cover-abundance values to presence-absence data, but this means a severe loss of information. A standardization of values by species maxima as is done automatically in some programs, may lead to an undesirable emphasis on species represented with low values only. In this paper a method is presented, by which relatively low cover-abundance values of species are upweighted to an arbitrarily chosen higher value, if these low values are considered to indicate an optimum response of that particular species. The method has been tested on a selection of 40 phytosociological relevés from dune slacks in the Voorne dunes, as well as on the Dune Meadow data set used in the textbook of Jongman et al. (1987). The cluster structure obtained with the optimum-transformation appears to be clearer and the contribution of typical dune slack species to the cluster structure increased significantly. Canonical correspondence analysis of the transformed data gave slightly more important main axes.

Reversible jump MCMC for nonparametric drift estimation for diffusion processes

In the context of nonparametric Bayesian estimation a Markov chain Monte Carlo algorithm is devised and implemented to sample from the posterior distribution of the drift function of a continuously or discretely observed one-dimensional diffusion. The drift is modeled by a scaled linear combination of basis functions with a Gaussian prior on the coefficients. The scaling parameter is equipped with a partially conjugate prior. The number of basis functions in the drift is equipped with a prior distribution as well. For continuous data, a reversible jump Markov chain algorithm enables the exploration of the posterior over models of varying dimension. Subsequently, it is explained how data-augmentation can be used to extend the algorithm to deal with diffusions observed discretely in time. Some examples illustrate that the method can give satisfactory results. In these examples a comparison is made with another existing method as well.

Estimating a concave distribution function from data corrupted with additive noise

We consider two nonparametric procedures for estimating a concave distribution function based on data corrupted with additive noise generated by a bounded decreasing density on (0, ?). For the maximum likelihood (ML) estimator and least squares (LS) estimator, we state qualitative properties, prove consistency and propose a computational algorithm. For the LS estimator and its derivative, we also derive the pointwise asymptotic distribution. Moreover, the rate n?2/5 achieved by the LS estimator is shown to be minimax for estimating the distribution function at a fixed point.

Development of new dunes in the Dutch Delta: nature compensation and ‘building with nature’

A new dune area was constructed by beach and foreshore nourishments along the Delfland Coast in the southwestern Netherlands. The new area is intended to be a compensation for losses of existing high quality dunes in nearby areas, due to the use/construction of Maasvlakte 2, the new harbour extension of Rotterdam opening in 2013. The target habitats for compensation include dry grey dunes and moist dune valley grassland. Due to the habitat type, the nourished material had to have a special character. The nourishment was carried out according to a special design and initial development of the new area had to follow certain pathways. In order to meet the compensation requirements in time. Careful monitoring is done to assess whether development of the new habitat is taking place in the direction of the desired target habitats. This paper reports on the construction of the new area and on the first years of development and monitoring. The monitoring mainly concerns development of the abiotic landscape elements, geomorphology, groundwater and soils. The lessons learned from this area are discussed in the light of the development of other recent young nature areas in the sandy Dutch delta coast. This gives new insights for coastal management in general in the context of building with nature.

The Journal of Coastal Conservation, 1995–2004

This paper concludes the publication of theJournal of Coastal Conservation from 1995–2004 after the European Coastal Union and the Publishers decided to terminate the production of the journal. We look back at the 206 research papers published in this period while concentrating on Geographical and ecological variation, Focuses and trends, and Progress in European coastal conservation and management.Three indices are added: (1) a list of the 206 papers; (2) an Author Index; and (3) a Subject Index based on the titles, keywords and some additional important subjects found in the tables and figures.Abstract This paper concludes the publication of the Journal of Coastal Conservation from 1995–2004 after the European Coastal Union and the Publishers decided to terminate the production of the journal. We look back at the 206 research papers published in this period while concentrating on Geographical and ecological variation, Focuses and trends, and Progress in European coastal conservation and management. Three indices are added: (1) a list of the 206 papers; (2) an Author Index; and (3) a Subject Index based on the titles, keywords and some additional important subjects found in the tables and figures.

A non-parametric Bayesian approach to decompounding from high frequency data

Given a sample from a discretely observed compound Poisson process, we consider non-parametric estimation of the density

Estimating the age of Risso’s dolphins (Grampus griseus) based on skin appearance

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