摘要:

SUMMARYThe author gives a discussion on the occurrence and distribution ofCerastium pumilumin the Netherlands. Two subspecies have been collected in this country, viz. subsp.pallens(F. W. Schultz) Schinz&Thell., and subsp.pumilum. Often the plants grow on sea‐dikes, though both subspecies have also been found further inlan

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01239.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYThe finds of micro‐ and macro‐subfossils of the walnut (Juglans regiaL.) in southeastern Europe strongly suggest that this tree was introduced by man. The appearance ofJuglansin Greece is connected with that ofCastaneaandPlatanus. The time of arrival of this species and a way in which it was possibly introduced on the southern mainland of Greece will be discussed in this article with reference to a pollen diagram from Lake Trikhonis. A relation of the walnut with the Mycenaean culture is suggested, linked in time with the Santorini erupt

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01240.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYIn the Kuinderbos forestry (1100 ha) planted 26–31 years ago in the N.E. Polder an ecological investigation of the ferns was carried out in 1979. The 23 species found represent nearly the complete Dutch fern flora; two species are new to The Netherlands. The establishment of so many species reflects the great dispersal capacity of the group and seems to be evoked by the presence of a great length of ditches (240 km), opening various types of soil under different tree species.The ditch environment markedly differs from the known habitat of many of the species in NW Europe. Correlations between species and environmental factors (e.g. pH, organic matter, lime content and light intensity) were in good agreement with literature data; their ecological amplitude seems to be widened in this young fores

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01241.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYTheCarexfloras of five inland landscapes in The Netherlands (fig. 1) are compared to each other, with emphasis on phytogeographical, syntaxonomical and ecological aspects (table 1). Moreover, changes in the distribution frequencies of theCarexspecies have been analysed by comparing two sets of frequency data to each other (census periods 1900–1949 and 1950–1975; cf.table 3). A strong decrease is noticed in many species: both in species occurring in The Netherlands at the margin of their phytogeographical range and in species occurring near the central parts of their range (table 4). In relation to habitat (table 5) little decrease is found in the species groups of dynamical and eutrophic environments; on the contrary, a dramatic decline can be observed in many species associated to complex, stable (semi‐) natural habitats (e.g.Carex dioica: fig. 2). It is argued, that the real decrease of manyCarexspecies is much more severe than is indicated by the current census methods. At least 20 out of the 59 species of the NetherlandsCarexflora are threatened to such an extent, that probably they will only survive in a (very) few fitting Nature Reserves. The impoverishment of theCarexflora significantly reflects the recent changes in the Dutch flora as a whole. The high indicator value ofCarexspecies makes their disappearance the more regrettable from a scientific point of

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01242.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYBy comparing a recent inventory ofViscum albumL. (DeGraaf1980) with older data, it appeared that the number of provenances in The Netherlands has decreased drastically in recent years. However, the methods usually applied by Dutch botanists to determine the degree of this decline appears to be inadequate. This follows from a comparison of distribution maps based on different grid widths.Analysis of the habitats ofViscumsupports the surmise that the phytogeographical Chalk and Loess Districts cf. VanSoest(1929, 1977) should be rejoined into one Centreuropean District (cf. VanSoest1925).

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01243.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYThe literature on the geographic distribution and the habitat ofCotula coronopifoliaL. andRanunculus sceleratusL. is reviewed, and observations on the population development of these species during their colonization of Zuid Flevoland, a new polder in The Netherlands, are reported. A discussion is also given of some ecological characteristics indicating thatC. coronopifolia, a neophyte in Europe and introduced from southern Africa, is less adapted to its habitat thanR. sceleratus, which explains the ephemeral behaviour of the former species.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01244.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYDifferent flowering times ofPedicularis palustrisssp.palustris(May‐July) andP. palustrisssp.opsiantha(Ekm.) Almquist (July ‐ September) are related to variation of the life cycle: ssp.palustrisis a biennial, ssp.opsianthais a summer annual. Growth experiments confirmed the genetic basis of the difference. The biennial has rosette leaves in the first year, and forms a winter bud with scale‐like leaves. These leaves or their scars are visible in the flowering plant; they are missing from the annuals. Germination requirements are similar; fresh seeds germinate at rather high temperatures (25–30 C) only, but stratification widens this range. The adaptive nature of the life form is discussed in relation with the different habitats in which the taxa ar

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01245.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYShoots of couch (Elytrigia repens(L.) Desv.) were collected from several grasslands and arable fields from a sand‐and a clay area in The Netherlands and grown to adult plants on one experimental field. After three months these plants showed considerable variability which partly appeared to be related to the land use and locality of the sampled fields. However, land use and locality never accounted for more than 10 % of the total variation of the observed plant characteristics. This variability could not be attributed to characteristics of the planted shoots and therefore seemed to be genetically determined and consequently the result of selection of couch types by the environment. The ways in which the land use (grassland versus arable land) might have caused the selection of the couch types are discusse

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01246.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYThe perennial speciesSenecio erucifoliusL. is rare in the northern parts of The Netherlands. Its very local occurrence can hardly be explained by special environmental conditions.Ripe achenes are not formed until the middle of September. The achenes show no dormancy, but the initial temperature requirements for germination are relatively high. According to germination experiments, germination may take place during the whole winter half of the year, but the seedlings are very susceptible to frost, which reduces establishment from seeds. The apparent absence of seedlings in the field confirms these conclusions.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01247.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYIn the vascular flora of the main rock‐soil system known as serpentine south of Mt. Stuart of the Wenatchee Mountains of the Cascade Range (Washington, USA), leguminous species, such as members of the genusLupinus, are rare.Populations ofLupinus laxiflorus, L. lepidusvar.lobbii, andL. polyphylluswere investigated. These species occur also on non‐serpentine soils. The serpentine and non‐serpentine populations therefore may be regarded as edaphic ecotypes. One of the main questions is whether the effect of serpentine soil is reflected in the physiology of N‐fixingRhizobium lupini.The root systems of the three species are nodulated. There are no indications that serpentine populations have fewer root nodules than non‐serpentine populations. Bacteroïds ofR. lupiniare present in all the nodules.The strains ofR. lupiniall fix atmospheric nitrogen, but as compared to commercially available strains, their effectiveness is variable and in general low. Serpentine and non‐serpentine strains do not differ materially. The available evidence indicates that strains ofR. lupinidiffer physiologically, presumably in consonance with their edaphically differentiated host species, as far as nickel and magnesium are concerned.It is therefore unlikely that the rarity ofLupinus‐species on serpentine soil types is determined by the growth peculiarities ofR. lupiniunder the prevailing habi

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb01248.x

年代:1980

数据来源: WILEY