Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
Volume 10
Issue 4
Available Online: http://www.ejpau.media.pl/volume10/issue4/art-43.html


Tomasz Stosik
Department of Botany and Ecology, University of Technology and Life Sciences, Bydgoszcz, Poland



Russian Dock (Rumex confertus), an anthropophyte invading new locations in Poland, settles mainly in ruderal communities and hay-growing meadows. It alters penetrated phytocoenoses which leads to a decrease in biological diversity. Growing in meadows it reduces the fodder quality of hay. Studied populations of Russian Dock are patchily distributed. Ramet clusters covering ca. 1m2 are formed due to morphology of the species: its overground parts are joined with underground rhizomes. Spatial distribution of whole genets (clumps) is determined by habitat factors and varies among populations. Plants at earlier development stages inhabit different ecological niches, in a distance from generative genets. Spatial pattern depends also on sex of the individuals, which is clearly associated with different abundance of male and female specimens.

Key words: Russian Dock, Rumex confertus, spatial structure, population.


Rumex confertus is an anthropophyte vigorously spreading in Poland. It exhibits features that enable quick covering of new areas and settling in plant communities encountered. Seeds of the species are adopted to dispersal by the river current or by wind on valley bottom, and capable of long-distance movements.

In good habitat conditions seedlings of Russian Dock appear, and a local population develops. Going through subsequent development phases (juvenile and virginile stages), which can take a few years, specimens start to form generative shoots. Then sexual differentiation of the population manifests itself. Genets not producing fruit as well as shoots bearing fruit (with flowers functionally female mixed up with some bisexual ones) can be distinguished in the populations [20].

Perennial generative clumps prevail in age structure of Russian Dock. Plants at earlier development stages are rarely found [1,6].

Sex ratio depends on population density. According to Almazova and Rabotnov [1] varies from 1:1 for high-density populations immediately close to a river, to 1:3 or even 1:10 in more distant valley locations, where the population density is lower. Faliński [8] came to similar conclusions and reported that the ratio of functionally male specimens to those bearing fruit ranges from 1:3 to 1:1.

Statistical analysis of the material yields synthetic indices estimating distribution type and degree of spatial clustering, which are of special value when different objects are compared [18]. Spatial structure appraisal in accordance with classification proposed by Chessel [4] is often used in population studies. Clustered distribution was the most frequently ascertained type [5,21,23].

Therefore it can be assumed that Russian Dock forms clusters in its populations. The assumption is expected to be valid when all specimens are taken into account, as well as for some groups of individuals pre-selected according to some criteria.

The aim of this paper is analyzing the spatial structure of various Rumex confertus populations, determining the size of clusters formed, and describing spatial relations between specimens of different sex and at different development stage.


Rumex confertus prefers meadows and ruderal communities of different kind. In this work three populations of Russian Dock growing in different phytocoenoses were analyzed. One of the objects analyzed was an extensively used periodically flooded meadow (population A). Two other objects represent ruderal communities: the first one is developed close to the river-bed (population B), the second one occurs on a side-space of an unpaved road surrounded by plough-lands (population C). In these areas, in places where density of the species was high, permanent sample plots of the size 8/16 m were set up according to methodology suggested in the literature of the subject [9,10,15,16].

Because of specific morphology of Rumex confertus, ramets in the form of vegetative leaf rosettes or generative shoots were assumed to be research units. Following Gatsuk et al. [11], five development stages of genets sensu Harper [13] were distinguished: seedling, juvenile, virginile, reproductive (generative) and secondary vegetative phase.

In autumn 1999 for each permanent sample plot a cartogram showing distribution of ramets in a grid of size 0.5 x 0.5 m was made. The development stage of genet, number of vegetative rosettes, and the number and sex of generative shoots were reported during three subsequent growing seasons.

The above mentioned procedures enabled determination of density of ramets, their spatial distribution pattern, and the age and sex structure of populations. For statistical analysis of the species distribution pattern the dispersion index, known also as Lexis index [2,5,16,17], was used. In this method, the number of shoots per area unit (chosen individually for a given species) serves as the analyzed variable. Its deviation from 1 is assumed to be significant, if it exceeds two standard errors [16]:

where IL – Lexis index, s2 – variance and x – arithmetic mean.

Shoot spatial distribution pattern was determined using data gathered in a grid. Basic unit was a square of the side 0.5 m; subsequent blocks were created by multiplying the basic unit: 1x, 2x, 4x, 8x, 16x, 32x, 64x, 128x and 256x. Then the variance analysis was performed for the number of sample squares in the block. In the diagram showing the variance for blocks of different size, the subsequent spatial clustering patterns are marked as peaks corresponding to the average cluster size. This method can detect differences in population density which are not recognizable by sight [14].


The spatial structure of Rumex confertus populations is determined mainly by ramets that are parts of perennial genets at generative development stage, as influx of new specimens of generative origin is low. Because of the species features, changes noticed in subsequent years do not influence the spatial distribution pattern significantly.

The maximum density was reported for meadow population reaching there over 8 ramets per square meter. The density in ruderal communities was lower (Fig. 1).

Fig. 1. Density of ramets (n) and genets (N) of Rumex confertus populations (A, B and C) within three subsequent years

Values of Lexis index for each level and each population analyzed suggest clustered distribution. Deviation of Lexis index values from 1 is considerable; an even distribution pattern can be seen for large blocks only (Fig. 2).

Fig. 2. Values of Lexis index vs. sample plot area; A, B, C – sample plots, BS – area of statistically insignificant deviation

Analysis of cluster hierarchy enables not only revealing the spatial structure of a population, but also determining the size of patches. The scale of clustered distribution varies from population to population. There are differences between particular plots due to different density. High variability in the number of shoots results in differences between growing seasons (Fig. 3).

Fig. 3. Morphological and habitat distribution patterns of Rumex confertus genets on permanent plots within subsequent years

In population A, probably due to high density, variance values ranging from 55 to 93 can be observed for 64 and 128 sample units. Such clusters of size 16 and 32 m2 represent habitat-related clustered distribution (so called habitat patterns) [14].

Distribution patterns of genets in populations B and C differ from the described above mainly in much lower variance. The highest variance in the permanent plot B was recorded in 2002 for the block of size 8 m2. Therefore the clusters are habitat-related, though in this case the patches are smaller. Similarly to the previous case, morphological pattern manifests itself with shoot clusters in blocks of size1 m2. The effect of variance increasing with the size of sample plots is quite unusual and suggests large differences in shoot number. Variance for the sample plot C is similar to that of the sample plot B. It points to the blocks of the size 16 m2. The morphological pattern exhibits itself in blocks of size 2 m2 which means that ramet clusters are slightly bigger here.

Comparison of spatial distribution of specimens at generative development stage and younger reveals that so called morphological pattern in both cases points to clusters in blocks of size 1 m2. It is justifiable in the case of older genets that form distinct clumps. On the other hand, juvenile and more expanded virginile genets form similarly sized clusters of distinct ecological units.

As it was mentioned above, generative genets form clusters of size ranging from 16 to 32 m2, whereas specimens at younger development stages are clustered in smaller areas (4-8 m2) that are not taken up by big aggregations of genets at generative phase (Fig. 4).

Fig. 4. Distribution patterns of older and younger individuals in the sample plot in meadow population (A) in 2002 year

Comparison of spatial structure of different populations with regard to female and male genets reveals mainly two patterns of genet spatial distribution. Similarly to the analysis for the total number of genets, so called morphological pattern at small size of blocks is also manifested here. In populations A and B the cluster size is mainly 1 m2, in population C the clusters are usually as big as 2 m2. At this level the patterns are identical for both sexes. However, the cluster size usually varies in the case of habitat pattern. It is noteworthy that due to low number of genets, variance reaches considerably lower values, especially in ruderal populations (Fig. 5).

In accordance with expectations, clusters of Rumex confertus ramets present in its population spatial structure correspond with spatial distribution of particular genets. Statistical appraisal of the spatial distribution shows a considerable deviation of Lexis index value from 1. Therefore the shoots are significantly clustered in spatial distribution.

The scale of clustered distribution differs from case to case. Most distinct differences were noticed between populations; fluctuations within three years were minute, so were the quantitative changes. In different phytocoenoses clumps of ramets which are 1 m (or more) in diameter and differently sized clusters of genets could be seen.

Fig. 5. Distribution patterns of Rumex confertus Willd. genets vs. sex of specimens in 2002 year

Therefore, clusters determined by the species morphology and those associated with the habitat factors are not constant in size. Clusters of ramets are a consequence of the Russian Dock biology: its overground parts are joined with underground rhizomes. The clusters of expanding single ramets are usually 1 m2 in size, but sometimes, as in population C, they are as big as 2 m2. This is supported by Rabotnov and Bylova [20] who report that clusters of ramets in many years’ clumps of the species grow up top 100 cm and then split into descendant units. In turn, distribution of whole genets is determined by the habitat factors. This might be brought about by soil surface structure of which in turn influences water movement, and physical/chemical soil features [3]. These factors are of special importance when seedlings appear. According to Wang et al. [22], they start to grow in clusters, but in the course of time as a result of elimination of some new individuals, their distribution becomes nearly random. This hypothesis probably holds true for annual plants. In case of perennials like Rumex confertus, the clusters of genets are permanent. In a meadow they merge into larger units (16-32 m2) than in ruderal populations. This may be ascribed to anthropogenic influence. Grazing an hay-making stimulates the sleeping buds, and the temporary restriction on between-species competition additionally contributes to the expansion of the clusters.

Specimens at early development stages can gather around parental individuals, as is reported for population of Cytisus scoparius [18], or, because of unfavorable interactions, move to more distant places. It is well known fact that specimens at early and mature development stages coexisting in a population have different ecological niches [12,18,19,22]. Among Rumex confertus populations analyzed, seedlings and their further development were observed only in meadow. As it could be easily noticed, the clusters of seedlings grew at a certain distance from mature individuals. Additional statistical analysis revealed in both cases clusters of area 1 m2 that reflect distribution structure of generative specimens and clusters of genets at earlier development.

Spatial patterns of both sexes are different, which can be clearly ascribed to the uneven participation of male and female specimens in population.


  1. The Russian Dock populations analyzed show a spatial cluster structure.

  2. Clusters of ramets of the area of about 1m2 are connected with the species biology.

  3. In respective populations genets create clusters of different size.

  4. Younger developmental stages occupy other ecological niches than genets at the generative stage.

  5. The spatial model of individuals of different genders is different and it is connected with their different share in the population.


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Accepted for print: 26.10.2007

Tomasz Stosik
Department of Botany and Ecology,
University of Technology and Life Sciences, Bydgoszcz, Poland
7 Prof. S. Kaliski St., 85-796 Bydgoszcz, Poland
Phone: +48 052 3408154
email: stosik@utp.edu.pl

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.