Kalevi Kull

Classifying clonal growth forms based on vegetative mobility and ramet longevity: a whole community analysis

We measured rhizome branching, clonal mobility, and ramet longevity of 98 meadow plant species. A cluster analysis applied to this dataset revealed nine clonal growth types that differ mainly by the ramet lifespan and vegetative mobility. Then we compared the abundance of these groups of clonal species between the three following plant communities: (1) open, (2) restored and (3) overgrown wooded meadows in the Laelatu-Nehatu-Puhtu Nature Reserve, Estonia. This is the first study where the quantitative values of belowground clonal traits have been measured for all species of a species-rich community. We show that species with annual ramets and with a low vegetative mobility were most abundant in open grasslands. The relative abundance of perennial species with annual ramets was positively correlated with shoot density and species diversity, indicating that high ramet turnover rates combined with a high genet longevity can positively affect species coexistence in meadow communities. Hence, this study provides evidence for the fact that the average values of clonal life-history parameters differ between these communities. Herb communities under forest canopy consist, in average, of species with ramets that live longer and are clonally more mobile than in the communities of open sites.

Competition intensity and its importance: results of field experiments with Anthoxanthum odoratum

Abstract The effect of community productivity on competition was studied in 82 permanent plots using two removal experiments with the rhizomatous perennial grass Anthoxanthum odoratum. The removal of neighbouring plants had a positive effect on the number of shoots and total above-ground biomass of Anthoxanthum but no significant effect on mean shoot biomass. The relative competition intensity coefficient (RCI) calculated from these data showed that competition intensity increased with increasing community productivity. Similarly, the importance of competition and the difference between local maximum and local average population density increased with increasing community productivity. We concluded that for Anthoxanthum the impact of competition is greater in high-productivity areas and that competition reduces population density. No evidence was found supporting the importance of positive interactions between plants in tundra areas.

Clonal growth in a species-rich grassland: Results of a 20-year fertilization experiment

We investigated the influence of fertilization on the abundance of species with different clonal growth characteristics using the data from a 20-year fertilization experiment from the Laelatu wooded meadow, in Estonia. The experiment comprised four different fertilization treatments and created a gradient of nitrogen availability. The vegetation composition was recorded every year by measuring the proportions of aboveground biomass for all species. For each species, four parameters of vegetative propagation were measured: speed of ramet vegetative mobility (annual increment of rhizome length), frequency of rhizome branching, placement of branches, and ramet life span. The weighted average of each parameter was calculated for each plot both at the beginning and at the end of the experiment using the relative abundances of the species in the plot as weights. The community changes resulting from the fertilization are reflected in the significant changes of the average values of all studied clonal growth parameters. Increased levels of phosphorus and potassium led to a community with an increased average vegetative mobility and rhizome branching. Both of these traits, however, declined with the increasing availability of nitrogen. The proportion of species with long-living ramets in the community decreased with the increase in the productivity irrespective of the fertilizer used. There was a strong positive correlation between the average ramet life span of the community and the number of species on the plot. We concluded that fertilization increased the ramet turnover rate in this meadow community and reduced species richness. Thus, our results contradict the prediction of a higher ramet turnover rate in species-rich compared to the species-poor grasslands.

A comparison of plant communities on the basis of their clonal growth patterns

This study was performed to analyse how a vegetative propagation pattern of plants affects the coexistence of species and subsequent species richness of the community. We compared community average clonal growth in the herbal communities of forests, wooded meadows, and open meadows in Laelatu, Estonia. The parameters used for the calculation of the community averages and measured for each species were ramet life span, rhizome branching, and clonal mobility. We also examined the intrinsic (i.e. independent of the environment) relationship between community clonal growth and plant species density. We found strong correlations between the environmental factors (productivity, light availability, and mowing regime) and community averages of clonal growth parameters, while species density was (negatively) correlated only with community average of rhizome increment. The community average of ramet life span decreased with the increasing biomass of the herb layer. No evidence was found to support the hypothesis that species-rich communities may consist of species with more contrasting mobility compared with species-poor communities. Independent of the effect of the environmental factors, species density was positively correlated with ramet density. There was intrinsic positive relationship between species density and community average of ramet life span at open meadow sites and intrinsic negative relationship between species density and community average of rhizome increment at wooded meadow sites. We conclude that in forest communities the capability of clonal plants to forage for light is favoured, while in unmown meadows a competitively strong phalanx growth form is advantageous. We established that ramet turnover increases and vegetative mobility decreases with increasing species diversity, although these two relationships depend strongly on the type of the studied community.

Ecosystems are Made of Semiosic Bonds: Consortia, Umwelten, Biophony and Ecological Codes

The paper focuses on the semiotic principles of the organisation of ecosystems, attempting to find concepts that point to relations and not to elements. (1) Consortium (the term introduced by Johannes Reinke around 1873) can be defined as a group of organisms connected via (sign) relations, or groups of interspecific semiosic links in biocoenosis. The consortial relations include trophic and topic relations, both implying a recognition (identification) of the object by an organism involved (these, i.e., are sign relations). These relations are ecologically inheritable. (2) Umwelt (the term introduced by Jakob von Uexküll around 1909) can be defined as a set of relations an organism has in an ecosystem (as in a semiosphere). The formation of an umwelt is dependent on the modelling system of the organism. (3) Biophony (the term introduced by Bernie Krause around 2000) denotes the coordination of inter- and intra-species relations in a soundscape of a biological community. This can be seen as a special case of Komposition as defined by Jakob and Thure von Uexküll. (4) Ecological code (as introduced, e.g. by Alexander Levich around 1977) can be defined as the set of (sign) relations (regular irreducible correspondences) characteristic to an entire ecosystem. We also mention the concepts of ecomones and coactones (introduced by Marcel Florkin in 1965) as the substances which are responsible for mediation of ecological inter-individual relations. All the relations as sign-relations evidently imply both a static or structuralist description (in terms of codes), and a processual description (in terms of semiosis carried on by interpretation). We conclude that all the above mentioned concepts can be viewed as conceptually connected and are suitable for semiotic description of biological communities.

Distribution trends of rare vascular plant species in Estonia

On the basis of quantitative analysis of the vascular plant distribution maps for Estonia, we specified the list of rare species which occur in less than 5% of grid quadrangles, and studied the possible correlations between their rarity and habitat preference, distribution, and sensitivity to human impact. Rare species occur statistically more often among species that are at the limit of their geographical range. The proportion of rare species was significantly higher among arctomontane and disjunct circumpolar taxa. Among apophytes, there were less rare taxa than would be expected according to the common native flora, but among hemerophobes, there were significantly more rare species than would be expected. The number of rare species was in strong positive correlation with the species richness of the region. Besides the western part of Estonia, where the greatest number of rare species occur, some small areas rich in rare species also lie in East and North Estonia.

ECOSEMIOTICS: MAIN PRINCIPLES AND CURRENT DEVELOPMENTS

Abstract Ecosemiotics studies the role of environmental perception and conceptual categorization in the design, construction, and transformation of environmental structures. This article provides a brief review of the history of ecosemiotics, and formulates eight core principles of the ecosemiotic approach. The ecosemiotic view understands humans as capable of both prelinguistic (biosemiotic) and linguistic (cultural) modelling of their environment. Accordingly, the diversity of structures is, to a certain extent, resultant of the types of semioses partaking in their formation. Ecosemiotics could provide geography with conceptual tools to describe the role of signs and communication in the dynamics of physical environments.

A more developed sign: interpreting the work of Jesper Hoffmeyer

Hoffmeyer’s work is so rich that it is difficult to comment on bits in isolation. I believe, however, that I have a few words that might help to illuminate the quote above. Hoffmeyer (2008) takes a distinctly Peircean approach to semiotics both for exosemiotics and endosemiotics, so one must assume that he thinks that the basic principles are much the same. Indeed, he points out that the distinction between exo and endo in biology is not clear-cut (2008: 213ff). His view is in contrast to well-known arguments by Barbieri that the two differ significantly, with endosemiotics satisfied by codes. Codes do not have, in any obvious way, a requirement for a Peircean interpretant (Collier 2008a: 778ff). I believe that Hoffmeyer has it right.

Semiosis stems from logical incompatibility in organic nature: Why biophysics does not see meaning, while biosemiotics does

We suggest here a model of the origin of the phenomenal world via the naturalization of logical conflict or incompatibility (which is broader than, but includes logical contradiction). Physics rules out the reality of meaning because of the method of formalization, which requires that logical conflicts cannot be part of the model. We argue that (a) meaning-making requires a logical conflict; (b) logical conflict assumes a phenomenal present; (c) phenomenological specious present occurs in living systems as widely as meaning-making; (d) it is possible to provide a physiological description of a system in which the phenomenal present appears and choices are made; (e) logical conflict, or incompatibility itself, is the mechanism of intentionality; (f) meaning-making is assured by scaffolding, which is a product of earlier choices, or decision-making, or interpretation. This model can be seen as a model of semiosis. It also allows putting physiology and phenomenology (or physics and semiotics) into a natural connection.

A biosemiotic conversation: Between physics and semiotics

In this dialogue, we discuss the contrast between inexorable physical laws and the semiotic freedom of life. We agree that material and symbolic structures require complementary descriptions, as do the many hierarchical levels of their organizations. We try to clarify our concepts of laws, constraints, rules, symbols, memory, interpreters, and semiotic control. We briefly describe our different personal backgrounds that led us to a biosemiotic approach, and we speculate on the future directions of biosemiotics.