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| Maarel, E. van der. |
| A short history of Dutch dune vegetation research is presented as an introduction to the present research in the Delta region. Remarkably enough the main results of dune research were presented as dissertations. The classics F. Holkema, L. Vuyck, J. Jeswiet, J. Bijhouwer and W. van Dieren are mentioned. The broadening basis is marked by the outstanding thesis of V. Westhoff, the first all-round phytosociological and ecological study of Dutch dunes. New ideas from this work are mentioned. The work of some pupils and collaborators of Westhoff is discussed. The new approach consists of concentration of the research in the Delta region, development of new ideas and establishment of field stations in the dunes. The scientific value of the Delta dunes is... |
| Tipo: Article / Letter to the editor |
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| Ano: 1966 |
URL: http://www.repository.naturalis.nl/record/534894 |
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| Maarel, E. van der. |
| Dit boek is het derde tot nu toe verschenen overzicht van plantengemeenschappen in Nederland, maar het is bepaald niet de derde druk van het welbekende „Overzicht der Plantengemeenschappen in Nederland” waarvan de 2e druk uit 1946 zo vele jaren de toeverlaat van de Nederlandse (en ook van vele buitenlandse) vegetatieonderzoekers is geweest. Het is, zoals de auteurs zelf uitdrukkelijk stellen een geheel nieuw boek. Het nieuwe slaat vooral op het feit dat in de naoorlogse periode een groot aantal plantensociologische publicaties is verschenen, waarvan de meeste in het voor ons liggende werk zijn verwerkt. Alleen reeds door de nauwgezetheid waarmee dit is geschied steekt het boek verre uit boven de meeste plantensociologische overzichten die in Europa tot... |
| Tipo: Article / Letter to the editor |
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| Ano: 1970 |
URL: http://www.repository.naturalis.nl/record/527900 |
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| Maarel, E. van der. |
| In a previous paper (VAN DER MAAREL, 6) the results of an investigation of herbarium specimens of Cochlearia officinalis and C. anglica as to their distinguishing characters have been published. Now similar measurements of populations of these two species are described of which the results are shown in fig. 1, a-d and table I. It appears that the so obtained averages are very near those found in measurements of herbarium specimens. Table II gives the 1% confidential limits of those averages. Characters a, d and f seem to be the most useful ones. The occurrence of intermediate populations is considered by the author as a result of introgressive hybridization. The importance of the phenomenon for the study of some aspects of plant taxonomy, ecology and... |
| Tipo: Article / Letter to the editor |
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| Ano: 1962 |
URL: http://www.repository.naturalis.nl/record/527057 |
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| Maarel, E. van der. |
| Flora statistics as a contribution to the evaluation of nature areas Flora statistics of an area are defined as a quantitatively elaborated species list of that area. Important aspects are: the total number of species as compared with the average number on an area of equal size, a rarity index and a plant sociological spectrum of the flora. Quantitative evaluation of nature areas, i.e. areas comprising natural or/and semi-natural biotic communities, based on diversity studies by PRESTON (1962) and WILLIAMS (1964) as well as plant geographical and sociological studies by WESTHOFF (1956, 1958), is now being further developed at the Nijmegen Geobotany Section. Detailed data on the distribution of vascular plant species from 1900 onwards are available GOETHART... |
| Tipo: Article / Letter to the editor |
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| Ano: 1971 |
URL: http://www.repository.naturalis.nl/record/526955 |
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| Maarel, E. van der. |
| Of Cochlearia officinalis L. and C. anglica L. 160 herbarium specimens with well developed basal and cauline leaves, and with flowers or mature fruits, all collected in the Netherlands, have been investigated. Fig. 1, j shows a theoretical frequency distribution curve of a single character for two well distinguishable species in general. Fig. 1, a-g show the frequency distribution curves of the measured characters of the species under discussion: a. angle of attachment of the lamina to the petiole in the basal leaves (explained in fig. 1, h and i for C. officinalis and C. anglica respectively); b. length-breadth relation of basal leaves; c. id. of stem leaves; d. length of petals; e. length of style; f. length-breadth relation of septum, and g. length of... |
| Tipo: Article / Letter to the editor |
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| Ano: 1962 |
URL: http://www.repository.naturalis.nl/record/527893 |
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