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  • 1
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    In:  Mededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht (2352-5754) vol.173 (1961) nr.1
    Publication Date: 2015-05-08
    Description: In the years 1954-1957 The Foundation for Biocenological Research (Stichting tot Onderzoek van Levensgemeenschappen, S.O.L.) carried out an extensive study on the vegetation of about 125 former river beds in the Netherlands. They were situated along the great rivers and their branches, viz. Meuse, Oude Maas (“Old Meuse”), Heusdense Maas (“Heusden Meuse”), Rhine, Lek, Merwede, Waal and IJsel. The work was made possible by a grant of the Netherlands Organisation for Pure Research (Nederlandse Organisatie voor Zuiver Wetenschappelijk Onderzoek, Z.W.O.). Dr. M. F. Mözer Bruijns proposed and supervised the investigation, and Dr. V. Westhoff took part in the interpretation of the results. The field work was carried out by A. J. Quené-Boterenbrood (1954-55), W. A. E. van Donselaar-ten Bokkel Huinink (1955-56), J. van Donselaar (1955— 57), Ir. L. G. Kop (1956-57), P. J. Schroevers (1954-55) and E. E. van der Voo (1954-57). Our study had several aims. The collected material had to contribute to our knowledge of a number of plant species and communities, especially of those playing a part in the hydrosere found in various kinds of water. With respect to the communities it should comprise their floristic composition as well as a definition of their habitat. Moreover, the former river beds should be classified according to their plant communities as well as to their abiotical properties. This classification should be useful as a basis for the choice of future naturereserves (see Gorter and Westhoff, 1952; Van Donselaar, 1956; Westhoff and Leentvaar, 1957).
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 2
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    In:  Mededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht (2352-5754) vol.309 (1968) nr.1 p.495
    Publication Date: 2015-05-08
    Description: In February and early March, 1961, the senior author spent three weeks on a small savanna in the approximate centre of Suriname, South of Tafelberg, (map 1). He was accompanied by Mr. W. H. A. Hekking. The time was spent in exploring the flora of the savanna and the adjacent forest. As a detailed study of the vegetation of the savannas of northern Suriname was then in progress, several extensive papers being in preparation (Heyligers, 1963; Van Donselaar, 1965; Van Donselaar-Ten Bokkel Huinink, 1966), it was felt that a more thorough inventory of the vegetation and the flora of the savanna might be rewarding. When a general impression of the plant-cover of the area had been obtained, eight representative sample-plots were selected, their vegetation was analyzed and described after the method of the French-Swiss school of phytosociology, and pits were dug in the soil down to bedrock, samples being taken in every distinctive-looking layer. This work was carried out jointly by the senior author and W. H. A. Hekking; part of the floristic exploration was also done by or with Dr. R. M. Tryon, Harvard Herbarium, Cambridge, Mass. The results are here presented. It was felt that in order to integrate them with those obtained elsewhere in Suriname, the collaboration of a specialist familiar with the Suriname savannas in general was required. This was the junior author’s task, who, after his prolonged work on the savannas of northern Suriname, later expanded his work to those of the southern part of the country. The preliminary results of the last-named study are in the press; more detailed field work is in progress as this paper goes to the press.
    Repository Name: National Museum of Natural History, Netherlands
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  • 3
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    In:  Mededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht (2352-5754) vol.326 (1969) nr.1 p.271
    Publication Date: 2015-05-08
    Description: The vegetation was studied of a number of savannas in northern and southern Surinam, and in French Guiana. The results are compared in particular with the vegetation classification proposed earlier for northern Surinam, and with some records from the northern Rupununi Savanna, Guyana (Van Donselaar 1965). The savannas studied near Brownsweg (northern Surinam) have vegetation types that correspond completely with those of some other savannas of the same geological-pedological type more to the North, as described before. New is the finding of a type of scrub bordering the savanna, being the scrub equivalent of a type of bushes described earlier as the Marlierea type. On the top and the slopes of the Blauwe Berg near Berg en Dal (northern Surinam) an anthropogenic savanna has developed. Two new vegetation types are recorded here that belong to the alliance Rhynchosporo-Trachypogonion. At the foot of the hill a flat savanna supports a vegetation that gives the impression of being of recent origin and unbalanced. It appears possible to apply the existing classification to the communities found on savannas near Cayenne (French Guiana). In this area the conspicuous Byrsonima verbascifolia (var. villosa fo. spathulata) occurs in several undescribed vegetation types that belong to various entities. A xerophilous and a hygrophilous community of Byrsonima verbascifolia are distinguished, belonging to the Rhynchosporo-Trachypogonion and the Bulbostylidion lanatae, respectively. On the Sipaliwini Savanna in southern Surinam most vegetation types do not fit into one of the existing alliances. However, if new alliances would be described, it should be possible to include them into the existing orders. There probably is an alliance, called here “communities of Trachypogon plumosus and Bulbostylis spadicea”, that might be regarded as the southern counterpart of the Rhynchosporo-Trachypogonion in the order Trachypogonetalia plumosi, and a supposed alliance with much Rhynchospora graminea and R. globosa might have the same position with regard to the Imperato-Mesosetion in the order Paspaletalia pulchelli. Among the communities that might be included in the alliance Axonopodion chrysitidis there is one occurring on sandy soil without a hog-wallow structure at the surface. Floristically it has connections with the Paspaletalia pulchelli but it also has many characteristic species of its own. Whether this community has to be placed in a distinct alliance will have to depend on the results of further investigations in this area. Anyhow, more data are needed for the drafting of a complete picture of the rich and interesting Sipaliwini Savanna. On a savanna south-west of the airstrip “Sipaliwini” (southern Surinam) the vegetation consists mainly of communities belonging to the Bulbostylidion lanatae. Summarizing the above-mentioned results, one may say that a number of communities not studied before are added to the picture of the savanna vegetation of the Guianas. It proved possible to integrate these communities without much difficulty in the classification presented earlier that so far has functioned as a practical framework.
    Repository Name: National Museum of Natural History, Netherlands
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  • 4
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    In:  Mededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht (2352-5754) vol.299 (1968) nr.1 p.183
    Publication Date: 2015-05-08
    Description: The Brokopondo Lake in the interior of Surinam began to form when on 1 February 1964 the dam in the Surinam River near Afobaka was closed. The lake was intended to cover an area of about 150.000 ha and to have a maximal depth of about 47 m. The basin, largely occupied by forest, was not cleared beforehand. During the initial stage the water in the flooded forest was characterised by a very high content of organic matter and the absence of oxygen. As the water level rose, differentiation between a hypolimnion and an epilimnion developed. The oxygen content of the epilimnion was high. During the first three years of its existence the lake attained an area of about 84.000 ha and a maximal depth of 38 m. Within this period eight aquatic plant species became numerous in the lake. Special attention was paid to Eichhornia crassipes and Ceratopteris pteridoides. In April 1966, when the lake covered about 78.000 ha, the former had colonized 53%, the latter 21 % of this area. Since September 1966 both diminished greatly, Eichhornia as a result of artificial control, Ceratopteris for unknown reasons. Floating pieces of decaying wood became overgrown by a variety of plant species, 27 of which were recorded. Mixed vegetations of water and marsh plants developed, free-floating mats ( Eichhornia being the matrix), patches attached to partly submerged tree tops, and belts along the shore. Twentytwo species were observed as constituents of these floating vegetations.
    Repository Name: National Museum of Natural History, Netherlands
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  • 5
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    In:  Mededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht (2352-5754) vol.328 (1969) nr.1 p.3
    Publication Date: 2015-05-08
    Description: In his preliminary revision of the genus Ceratopteris Benedict (1909) distinguished four species: C. thalictraides (L.) Brongn., C. pteridoides (Hook.) Hieron., C. deltoidea Benedict, and C. lockhartii (Hook. & Grev.) Kunze. Two more names were said to deserve further investigation: C. cornuta (Palisot) LePrieur and C. gaudichaudii Brongn. Since then the first four have not been in dispute, C. cornuta has become generally recognized, and C. gaudichaudii has remained doubtful (Fosberg, 1958). Most of the species of Ceratopteris are widely distributed. Ceratopteris thalictroides occurs in tropical Asia, Australia, and America (Benedict, 1909; Morton, 1967). Ceratopteris pteridoides is known from tropical America, subtropical South America, and continental tropical and subtropical eastern Asia (De Vol, 1957). Ceratopteris deltoidea is now known only from Florida, Central America, Jamaica, Porto Rico, Guyana, and Surinam. It has probably disappeared from Louisiana (Benedict, 1909; De Vol, 1956). Ceratopteris lockhartii is known from Trinidad, Guyana, and French Guiana (Benedict, 1909), C. cornuta from tropical and subtropical Africa, and C. gaudichaudii from Guam.
    Repository Name: National Museum of Natural History, Netherlands
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  • 6
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    In:  Mededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht (2352-5754) vol.336 (1970) nr.1 p.287
    Publication Date: 2015-05-08
    Description: Lianes, defined as woody climbers and (facultatively) straggling shrubs, were collected in an area of about 1900 square kilometres of the Brokopondo District, in the interior of Surinam. Ten different habitats were distinguished only one of which was intensively sampled, viz. the so-called “high forest”, the most luxuriant climax vegetation type in the area. A total of 132 species were distinguished, 80 of which could be determined with certainty and 15 nearly so. Among the identified species one was new (described since as Dicranostyles guianensis A. Mennega, Conv.), and 5 were new records for Surinam, viz. Sparattanthelium aruakorum Tutin (Hern.), Abuta obovata Diels, Abula splendida Kruk. et Mold., and Sciadotenia sagotiana (Eichl.) Diels (all Menisp.), and Mimosa micracantha Benth. (Mim.). The distribution of the species over the 10 habitat types is shown, and the ecology of some of them is discussed more in detail.
    Repository Name: National Museum of Natural History, Netherlands
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  • 7
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    In:  Mededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht (2352-5754) vol.211 (1965) nr.1 p.1
    Publication Date: 2015-05-08
    Description: Geology and soils in general Surinam is situated at the northern edge of the very old and stable Guiana shield. Six-sevenths of the country’s surface are occupied by formations belonging to the shield and designated together as the basal complex. However, the Roraima formation does not belong to the complex. It was deposited during the Mesozoic (probably the Cretaceous) as a thick layer mainly consisting of sandstone that covered the greater part of the shield. Later on the original sandstone plateau was dissected, a process accelerated by the uplifting of the shield, and finally it disappeared almost completely by erosion. The former surface is now only represented by the flat tops of some table-mountains one of which is found in the interior of Surinam: Tafelberg. See Schols & Cohen (1953). The surface of the northern seventh part of the country is occupied by deposits of Quaternary age. In general may be distinguished (from the south to the north): 1) The Zanderij formation, consisting mainly of sands of continental origin; 2) the Coropina formation, comprising the “old coastal plain”; the main parts are (a) the so-called “schols”, i.e. the remnants of an old sea-clay plain, separated by filled-up tidal gullies, and (b) the remnants of the offshore bars that formerly separated the plain from the sea; 3) the Demerara formation, comprising the “young coastal plain”. See Van der Eyk (1954, 1957). Geological-pedological classification of the savannas Savannas are found on the basal complex, the Roraima, the Zanderij and the Coropina formation. Cohen & Van der Eyk (1953) classify them as follows: I Savannas of the Coropina formation 1. Watamalejo-type – on the offshore bars 2. Welgelegen-type – on the “schols” II Savannas of the Zanderij formation a. Kasipora-type – on dry bleached sand soils b. Zanderij-type – on wet bleached sand soils c. Coesewijne-type – on non-bleached soils III Savannas of the Roraima formation: Tafelberg-type IV Savannas of the basal complex 1. Paroe-type – on granitic soils 2. Bosland-type – on schist hills 3. Saban-pasi-type – on subgraywacke hills Savanna soils The climate is characterized by the sequence of a long rainy season (April-July), a long dry season (August-November), a short rainy season (December-January) and a short dry season (February-March). In connection with this periodicity the water-table in many places fluctuates strongly in the course of the year. During the dry seasons the upper layers of the savanna soils are always completely dry, except just after a shower. A soil is called very dry if even during the rainy seasons the upper layers are not influenced by the ground water. A very wet soil, however, at this period is covered by some cm of water; in addition it is characterized by many small hummocks, in Surinam called “kawfoetoes”, which are built up by worms and in which these animals are able to keep their heads above the water. Certain soils occur that in spite of deep watertables are wet, because an impermeable layer in the subsoil impedes drainage of the topsoil. Of course there is a scala between the extremes “very dry” and “very wet”. The texture of the upper layers ranges from bleached and slightly red sand to sandy and silty clay. Object of the investigation The flora and the vegetation of the northern Surinam savannas are the object of this investigation. These savannas do not only represent the types of the Zanderijand the Coropina-formation, but also the Bosland- and the Saban-pasi-type, for these two types are present on the basal complex only near its northern border. The following savannas have been studied. Welgelegen-type: the savannas of Bersaba and Vierkinderen, the Bigi-olo savanna near Hanover and the Fransina savanna near Welgelegen; Kasipora- and Zanderij-type: the white-sandy part of the Lobin savanna near Zanderij; Coesewijne-type: the loamy part of the Lobin savanna, the savanna Mimili Okili near Powaka, the Doti savanna near Wisawini and the Coesewijne savanna near Bigipoika; Saban-pasi-type: the Gros savanna and the De Jong Noord savanna. Data of some other authors pertaining to these and the other types have also been taken into account, some published (Lanjouw, 1936; Maguire c.s., 1948; Heyligers, 1963), some unpublished. The savannas present a marked diversity, among other things with regard to the structure of their vegetation. However, nearly all satisfy this definition: “A savanna (or a campo) is an area with a xeromorphic vegetation comprising an ecologically dominant ground layer consisting mainly of grasses, sometimes together with sedges, and with or without trees and/or shrubs either forming a more or less continuous layer, or in groups, or isolated.” The species have been studied with respect to the relation with the habitat, the means of dispersal and the area of distribution, all in mutual correlation. Vegetationunits have been distinguished and classified; ecological and chorologic aspects have been taken into account. A combination of all data, obtained during this as well as former investigations by others, permits the drawing of a provisional and general picture of the flora and the vegetation of the northern Surinam savannas as far as the present aspects are concerned. The following statements all apply to N. Surinam only, unless mentioned otherwise. Flora Habitat in general. Nearly all plants occurring on the savannas are heliophilous and are able to survive repeated burning. The flora of the open vegetation types consists of about 270 species the majority of which (72 %) is restricted to the open savannas. However, there are species occurring either in other open situations too, partly as weeds (8 %), or on wet savannas and other wet places (3 %), or in savanna rivulets and in swamps (7 %), or in savanna bushes (8 %). Out of ca. 100 species of the savanna bushes only 15 % are restricted to this vegetation type. The other species occur either also in the open savanna (20 %), or along forest borders (8 %), or in savanna wood and forest (23 %) and/or even in rain forest (31 %). A group of 12 % belonging to the last category does not flower or even not grow high in the bushes. Quite apart from this division other groups may be distinguished among the species of the bushes in the following way: occurring also in secondary forest (31 %) in marsh forest (9 %), in swamps (3 %). The trees and shrubs of the savannas support only few epiphytes and (half-) parasites; these belong to 19 different species. In the field nearly all species show some (factual) range with regard to the degree of moistness and the texture of the soil. The texture itself is not necessarily the decisive factor as there is a relation between the texture and some other properties of the soil, e.g. the consistency and the mineral content. This has not been further investigated. The same holds for the species preferring slightly shaded localities. These spots have a microclimate that differs more from that of its surroundings than in light intensity only. The majority of the open-savanna species have diaspores that are not obviously adapted to any agent of dispersal (71 %). The remaining 29 % are distributed over 6 different categories. The diaspores of the species of the bushes belong partly to the non-adapted forms too (35 %), but 50 % of them are fleshy. Generally speaking, the savanna species have a wider geographic distribution than the spieces of the flora of Surinam as a whole. This is particularly true for the opensavanna species. On the basis of similar areas of distribution the species are classed under 6 geographic elements, viz. the Guianan (G), the northern South-American (N), the northern + eastern South-American (NE), the Middle- and northern + eastern South-American (MNE), the South-American (S) and the American element (A). The distribution of the species of the open-savanna vegetations and of the bushes, respectively, among the geographic elements is as follows (percentages): G 12 : 26; N 11: 18; NE 16 : 13; MNE 10 ; 3; S 9 : 18; A 42 : 22. It appears from a comparison of these figures too, that the species of the first group in general have a wider distribution. Apart from the geographic elements the Roraima element has been distinguished. It comprises all species collected on one or several of the table-mountains in the Guianan interior. The distribution of these species among the geographic elements does not differ considerably from the one of the savanna flora as a whole. It may have appeared already from the foregoing that the species of the bushes, though presenting a higher percentage of adapted diaspores, nevertheless do not have areas of distribution wider than those of the open-savanna species. The expected correlation is, however, apparent if the two groups are considered separately: the mean area of distribution of the species with adapted diaspores is wider than the one of those with non-adapted diaspores. A comparison of the ecological and the chorologic aspects brings to the fore two focal points within the savanna flora: The elements with a small distribution (G and N) are most numerously represented on wet to very wet sandy (in particular white-sandy) soils, whereas the elements with a wide distribution (MNE, S and A) are concentrated on dry and moist non-bleached sands and loams and on very wet soils and present a preference-top on dry and moist loamy sand. The Roraima species are by far the most numerous on the wet white sand, in general they are more numerous on wet than on dry soils. Vegetation Vegetation-units have been distinguished and classified according to the BraunBlanquel school. It has been attempted to make the groups of so-called characteristic and differential species correspond with ecological groups in the sense of Duvigneaud (1946, 1949). The latter consist of species with clear, sociological affinities between them because of similar habitat requirements. The open-savanna (and orchard-savanna) vegetation-types have been united into a single class which is defined and divided as follows: Class Leptocoryphio-Trachypogonetea. Principal species; Trachypogon plumosus, Leptocoryphium lanatum, Axonopus pulcher and Rhynchospora barbata. It seems likely that this class and its subdivision up to and including the alliances may be applied to the whole of Guiana. 1. Order Trachypogonetalia plumosi. Principal species: Trachypogon plumosus, Axonopus pulcher and Bulbostylis junciformis. On very dry to moist soils. 1.1. Alliance Cassio (ramosae)-Trachypogonion. Principal species: Axonopus pulcher Trachypogon plumosus, and Bulbostylis conifera. On white sands. There are 3 or 4 associations two of which occur on open patches between so-called muri-bushes (see B1). Distribution: Kasipora-type; Guiana and adjoining parts of Brazil. 1.2. Alliance Curatello-Trachypogonion. Among the many tens of species the most common ones are Trachypogon plumosus, Axonopus pulcher, Schizachyrium riedelii and Heliconia psitlacorum. Usually there is a thin layer of trees mainly consisting of Curalella americana, giving the vegetation the aspect of a type of so-called orchard savanna. A rather large part of the species occurs outside the savannas on other open spots too. The alliance occurs on pure reddish and on loamy sands. On the savannas of the Coesewijne- and the Welgelegen-type 5 associations are present. Similar vegetation types are found throughout Guiana, on the central Venezuelan llanos and far into E. Brazil. 1.3. Alliance Rhynchosporo (barbatae) – Trachvpogonion. Principal species: Axonopus pulcher, Leptocoryphium lanatum, Mesosetum cayennense, Bulbostylis conifera and Rhynchospora barbata var. barbata. On sandy (clay) loam. Two associations on savannas of the Coesewijne-type; they are related to vegetation types in French Guiana and in regions farther to the west, up to the Venezuelan llanos and some of the West Indian Islands. 2. Order Paspaletalia pulchelli. Leptocoryphium lanatum is the only species which is common in all communities of this order. In general the vegetations are not closed. On wet (or even very wet) soils. 2.1. Alliance Syngonantho-Xyridion. Principal species: Paspalum pulchellum, Panicum micranthum, Rhynchospora barbata var. glabra, R. graminea, Xyris guianensis and Abolboda americana. On white sands, wet and very wet. Three associations are found on the savannas of the Zanderij- and the Watamalejo-type. Distribution: Guiana and adjoining parts of Brazil, also on the table-mountains of the Guianan highlands. 2.2. Alliance Bulbostylidion lanatae. Principal species: Trachvpogon plumosus, Paspalum pulchellum, Panicum micranthum, Mesosetum tenuifolium, Rhynchospora barbata var. barbata and R. rhizomatosa. On loamy sand and sandy loam; wet. In northern Surinam 5 associations occur on savannas of the Saban-pasi- and the Watamalejo-type. Distribution: Guiana, probably also on the table-mountains. 2.3. Alliance Imperato (brasiliensis)-Mesosetion (cayennensis). Principal species: Leptocoryphium lanatum, Mesosetum cayennense, Imperata brasiliensis, Rhynchospora barbata var. barbata and R. globosa. On wet sandy loam and heavier soil types. Four associations on savannas of the Coesewijne-, Welgelegen- and Saban-pasi-type. Related vegetation types occur, as far as known, only in regions more to the west, up to the llanos and Guatemala. 3. Order Panicelalia stenodis. Principal species: Leptocoryphium lanatum, Panicum nervosum, Hvpogynium virgatum, Heliconia psittacorum and Tibouchina aspera. On very wet soils, in savanna rivulets and small depressions. There are 2 alliances, both showing relationship with vegetation types occurring in regions more to the west, up to the llanos and some West Indian Islands. 3.1. Alliance Axonopodion chrysitis. Principal species: Leptocorvphium lanatum, Panicum nervosum, Rhynchospora globosa and Tibouchina aspera. On very wet soils of sandy loam and heavier. In N. Surinam 3 associations are found on savannas of the same types as alliance 2.3. 3.2. Alliance Mauritio-Hypogynion (virgati). Principal species: Hypogynium virgatum, Leptocoryphium lanatum, Panicum nervosum, Rhynchospora glauca, Heliconia psittacorum and Tibouchina aspera. Typical are the tall palms of Mauritia flexuosa. The alliance has rather many species in common with the communities of swamps, e.g. Blechnum indicum and Rhynchospora cyperoides. There are 3 associations, found in rivulets and depressions on savannas of all types. The different types of savanna-bushes are merely described. A classification on floristic grounds would be justified only if the savanna woods and forests were included in it too. B1. Ternstroemia-Matayba bushes. See Heyligers (1963). Principal species: Ternstroemia punctata, Clusia fockeana, Licania incana, Humiria balsamifera var. guianensis (“muri”), Pagamea capitata, Matayba opaca and Conomorpha magnoliifolia. On dry white sand. B2. Rapanea bushes. Principal species: Rapanea guianensis, Davilla aspera, Tapirira guianensis, Symplocos guianensis, Miconia rubiginosa, Byrsonima crassifolia, B. coccolobifolia and Curatella americana. On dry loamy sand and dry sandy loam. B3. Cupania bushes. Principal species: Cupania scrobiculata var. frondosa. Byrsonima crassifolia, Davilla aspera, Miconia ciliata, Maprounea guianensis, Symplocos guianensis Protium heptaphyllum, and Curatella americana. On moist loamy sand and moist sandy loam. B4. Clusia-Scleria bushes. See Heyligers (1963). Principal species: Licania incana, Clusia fockeana, Bactris campestris and Scleria pyramidalis. On wet white sand. B5. Marlierea bushes. Principal species: Marlierea montana, Bactris campestris and Licania incana. On wet loamy sand. B6. Roupala-Antonia bushes. Principal species: Roupala montana, Antonia ovata, Davilla aspera, Miconia ciliata, Bactris campestris, Licania incana, Humiria balsamifera div. var., Pagamea guianensis and Marlierea montana. On knolls of pebbles embedded in sandy loam; wet. Existence, origin and maintenance of the savannas There is no type of climate that accounts for a savanna vegetation irrespective of other conditions. However, a climate that permits the existence of savanna vegetations may be called a “savanna climate”. The latter is characterized by a certain difference between the precipitation in dry and wet seasons, independent of absolute values. The climate of northern Surinam is a savanna climate in this sense. A savanna vegetation is natural, i.e. determined edaphically, if the upper layer of the soil is alternately desiccated and saturated with water, thus in general in wet and very wet localities and in rivulets. As far as known the following savanna types and vegetation types are involved in this situation (the rivulets left out of consideration): Watamalejo (2.1) Welgelegen, partly (2.2), Zanderij (2.1 and B4), Saban-pasi (2.1 and B5, 2.2. and B6) and Bosland (?). A savanna vegetation occurs in dry localities only if fires prevent the formation of a closed layer of trees or shrubs. This is found among the following types: Welgelegen, partly (1.2 and 1.3), Coesewijne (1.2 and B2, 1.3 and B3) and Kasipora (1.1 and B1). Parts of the savannas of the Welgelegen-, Coesewijne- and Saban-pasi-type occupied now by vegetations of the Imperato-Mesosetion (2.3) and the Axonopodion chrysitis (3.1) would probably be overgrown very slowly by the surrounding forest and only starting from its edges if the fires were stopped. It might be easily assumed that savannas owing their maintenance at present only to deliberate burning, originated from forests as a result of human interference as well. However, the possibility may not be excluded that they came into existence very long ago, either caused by natural fires or in consequence of a water economy of the soil differing from the present one. Final conclusions All available data concerning the flora and the vegetation of the northern Surinam savannas justify the following theories: The wet white-sand savannas of the Zanderij-type have vegetation types (2.1) consisting of species that mainly stem from formerly or still existing savannas on the basal complex and on the Roraima formation, probably chiefly on the latter. These species may have reached the Zanderij formation either directly by means of series of savannas in the interior that still may have been present during the break-down of the Roraima plateau, or indirectly by the way of other sandy regions bordering the edges of the Guiana shield. The vegetations of the savannas belonging to the Saban-pasi-type on wet loamy sand and sandy loam (2.2) consist of species which already for a long time were common to the basal complex and the Roraima plateau or/and which originated from the plateau, and besides of species that developed on the basal complex or migrated from elsewhere to the subgraywacke-area. The savannas of the Watamalejo-type and of the Welgelegen-type N. of the Wane-creek have a flora that may be regarded as a selection from that of the two preceding types. The vegetation types on dry and moist, red, pure and loamy sands belonging to the Coesewijne- and the Welgelegen-type (1.2) have a high percentage of their species in common with the campos of central and eastern Brazil. It seems possible that these species came to N. Surinam from the campos. The species combination of the savanna vegetations from other habitats does not permit a conclusion with regard to their possible origin.
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 8
    Publication Date: 2015-05-08
    Description: Dans la végétation des dunes du Languedoc J. BRAUN-BLANQUET (1952) distingue trois associations, à savoir; 1) l’Agropyretum mediterraneum parmi et sur les premières dunes basses; 2) l’Ammophiletum arundinaceae sur les dunes plus hautes; et 3) le Crucianelletum maritimae dans les dépressions et en arrière des dunes. Or, il est établi que le développement de la première association et le passage de celle-ci à la deuxième sont accompagnés d’une édification de dunes, et que la troisième provient de la dégénérescence de la deuxième. KÜHNHOLTZ-LORDAT (1923) a le premier attiré l’attention sur le rôle essentiel joué par la végétation dans l’édification des dunes du Languedoc. Les résultats de ses recherches ont été confirmés par VAN DIEREN (1934) aux Pays-Bas. Les deux auteurs ont étudié le pouvoir accumulateur du sable par les parties aériennes des plantes; mais le premier seul donne aussi quelques indications sur le rôle édificateur des parties souterraines.
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 9
    Publication Date: 2015-05-08
    Description: Une évaluation des plantes d’après leur pouvoir édificateur de dunes doit être précédée d’une description de leur structure a côté de l’étendue et de la densité des organes aériens il faut considérer d’importance capitale et décisive la structure des organes souterrains, tel que KÜHNHOLTZLORDAT (1923) et VAN DIEREN (1934) l’ont suggeré. Les organes souterrains peuvent être: des rhizomes, des racines, ou des tiges ensevelies par le sable meuble. Une comparaison des différentes qualités mène à la distinction de groupements et à la création d’un système.
    Repository Name: National Museum of Natural History, Netherlands
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  • 10
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    In:  Mededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht (2352-5754) vol.112 (1952) nr.1 p.259
    Publication Date: 2015-05-08
    Description: Up till now the lower deposits of peat (in Dutch: veen-op-groterediepte = peat at greater depth) have been investigated in the Netherlands mainly in the Western part of the country, viz. in the provinces of Noord-Holland, Zuid-Holland and Zeeland. The analyses have shown that the development of this, now comparatively well known peat layer must have begun either in the second half of the boreal period or else in the beginning of the atlantic one, and that it must have come to an end in the first half of the latter. Among the earlier investigators the botanist Mrs VERNEER-LOUMAN and some geologists had arrived at the conclusion that the sudden transgression of the North sea which made an end to the formation of peat, took place in the boreal period, and hat the whole lower deposit of peat, therefore, was of boreal age (lit. 7). This opinion, however, was sufficiently disproved by FLORSCHÜTZ, and all subsequent analyses have confirmed the view that the peat formation must have stopped early in the atlantic period (lit. 2, 3, 4). The same conclusion was arrived at by GODWIN as a result of his investigations of the lower peat found in SE England (lit. 5, 6) and by several German investigators as a result of their analyses of the lower peat, found in NW Germany. Only one analyses of the lower peat in the province of Friesland, in the Northern part of the Netherlands, has sofar been published. The geologist VAN ANDEL found near Kiesterzijl, at a depth of only 3.50 m a thin layer of peat. He identified it with the lower peat from the W part of the Netherlands which occurs several meters deeper. His two diagrams show a boreal age for the basal layers and an atlantic age for the top ones and they confirm therefore the conclusions,obtained in the W part of the country (lit. 1).
    Repository Name: National Museum of Natural History, Netherlands
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