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PROCEEDINGS OF THE LATVIAN ACADEMY OF SCIENCES. Section B, Vol. 72 (2018), No. 4 (715), pp. 244–251 DOI: 10.2478/prolas-2018-0023 THE INFLUENCE OF PLANT DOMINANTS ON THE ASSOCIATED SPECIES ABUNDANCE IN WET TALL-HERB MEADOW PLANT COMMUNITIES Vera Lebedeva#, Marina Tikhodeyeva, and Elena Koptseva Saint-Petersburg State University, 7/9, University emb., St. Petersburg, 199034, RUSSIA # Corresponding author, [email protected] Communicated by Isaak Rashal Plant interactions in wet tall-herb meadow plant communities were described through dominant and edificator species identification. Five dominant species were identified: Alopecurus pratensis, Filipendula ulmaria, Deschampsia cespitosa, Anthriscus sylvestris, and Angelica sylvestris. The effects of species were studied using ANOVA and correlation analyses. Not all dominants were recognised as edificators. Edificators (Alopecurus pratensis, Filipendula ulmaria, Deschampsia cespitosa, Angelica sylvestris) had a negative effect on the various abundance indicators of asso- ciated species: percent cover, number, phytomass, and height. The edificator effects differed sig- nificantly in their level and duration and depended on the biomorphs of dominants. The perennial species Alopecurus pratensis, Filipendula ulmaria, and Deschampsia cespitosa were strong con- stant edificators. Angelica sylvestris, a short-lived monocarpic from the Apiaceae, is a weak sea- sonal edificator, while Anthriscus sylvestris is not an edificator. Analysis of the life strategies of species showed that competitors are not always edificators (Anthriscus sylvestris), whereas stress-tolerant may show edificator properties (Deschampsia cespitosa). The associated plant species often show positive interactions. Most of the associated species are stress-tolerant and have not an edificator effect. Key words: plant interactions, dominants, edificators, competitors, stress-tolerants. INTRODUCTION Rabotnov, 1984; Loheide and Gorelick, 2006). A reduction of grassland area creates understanding of the need to exam- Grassland (meadows) describe vegetation with dominance ine mechanisms for sustainable development and the rea- of perennial herbs, mostly grasses and sedges, which form a sons of their degradation (Muller et al., 1998; McDonald, sod. This article discusses the problem of grasslands exist- 2001; Middleton et al., 2006; Prach, 2007; Van Auken, ing in the conditions of sufficient or excessive moisture that 2009). were actively exploited by man as hayfields and pastures. In the second half of the 20th century, reduction in the area oc- Among multiple elements of a particular plant community, cupied by grasslands occurred worldwide and especially in dominant species have a key interest. Dominant species are regions of active land use. In some regions of the UK the defined here as most abundant, i.e. producing high cover area of grassland decreased by six times (Treweek, 1996), and biomass, species that play a significant community role in Eastern Europe and Russia by three times (Prach, 1993). via strong influence, either positive or negative, on the state This trend also continued in the 21st century (Prach, 2007). and abundance of the associated species (Hulbert, 1971; The grassland area reduction as a result of re-forestation Grime, 1998). The mass ratio hypothesis (Grime, 1998) (Woody encroachment) is associated with the termination of suggests that the traits and functional diversity of dominant use of the land as agricultural and natural grazing land and species largely determines ecosystem function. These domi- associated with climate changes (Magee and Antos, 1992; nant species can constrain subordinate species success and Miller and Halpern, 1998; Griffiths et al., 2005; Devine et diversity (Baer et al., 2004; McCain et al., 2010). Subordi- al., 2017). Grassland plays an important role in the mainte- nate species are generally relatively smaller in stature, less nance of the biosphere, because it is a habitat and a forage abundant and occupy more restricted microhabitats (Grime, base for more than half of the vertebrate species of the for- 1998), but can contribute most to floristic diversity, particu- est zone (Murphy et al., 2004; Ratajczak et al., 2012; Schir- larly in grassland (Gibson, 2009). Basing on identification mel et al., 2017). In addition, meadows regulate the hydro- of dominant species, spatial and functional aspects of plant logical regime of the territories (Shennikov, 1941; community structure can be described (Ipatov et al., 2010). 244 Proc. Latvian Acad. Sci., Section B, Vol. 72 (2018), No. 4. In analysis of plant community structure, the main attention Study of functional structure employs different features that is usually paid to spatial aspects, while functional aspects are often based on an experimental model of the environ- remain poorly studied (Keddy et al., 2002; Grime, 2006). ment and plant communities (Louault et al., 2005; Kraft et This is especially typical for wet meadow plant communi- al., 2015). For example, the effect of dominants on species ties under homogeneous environmental conditions, where invasion was examined in experimental grass crops (Emery community heterogeneity can arise from local functional and Gross, 2006; Souza et al., 2011). However, the role of traits due to wide number of species, and multiplicity of dominant species in communities, especially aspects of the dominant species (Keddy, 2010; Houseman and Gross, exclusion of subordinate species, is not well understood yet 2011). (Gibson et al., 2012). Our research was conducted in a meadow without any anthropogenic activity for more than The structure of grassland plant communities is usually an 50 years. It should be noted also that comparative analysis example of collective dominance. Their components can be of all dominants within the same grassland has not previ- the complexes of edificator sinusia, which become a single ously been conducted. In our work we used three basic con- whole in the development, creating a special microenviron- cepts: the dominant (the indicator of high abundance of the ment. The concept of “edificators” as the creators or build- species), the edificator (the indicator of strong influence on ers of plant communities was developed in the beginning of the surrounding vegetation), and the competitor (the type of 20th century (Brawn-Blanquet and Pavillard, 1922). By the life strategy for Grime). Are these concepts identical? Are way, this term is widely distributed in the Russian-language dominants or competitors always edificators, or not? The literature. Later on, in the works of L. G. Ramensky (1935) aim of this work was to determine the relationship of these and later J. P. Grime (1979), the concept of “strategy of characteristics in different meadow species. For this we de- life” based on biological abilities of species to occupy and fined the community role of all species, identification of hold a space was an important step in understanding the be- dominants and their edificator strategy and features of their haviour and interactions of species in plant communities. influence on vegetation. Our study of plant relationships The strategy of dominant species can be described as vio- was based on the use of abundance indicators like percent lent (Ramensky, 1935) or competitive (Grime, 1979). cover, species saturation (number of species per plot) and phytomass. The main indicator for assessing the edificator effect was the associated species abundance changes in a Fluctuating change of dominants in grassland plant commu- gradient of edificator abundance variation in plots 0.1 m2, nities is often observed (Rabotnov, 1967; 1996). This hap- comparable to the edificator sizes. The composition of asso- pens when the autecological optima of plant species are dif- ciated species was studied by analysis of morphological ferent and benefit is given to those or other species on the groups of species and types of life strategies for Grime. This background of seasonal, inter-annual and multi-annual cy- study will be useful in studying the spatial and functional clical climatic changes. Thus, spatial and functional diver- structure of the grassland community and to develop criteria sity of the dominants not only determines the heterogeneity of its sustainability. of meadow vegetation but it is also very important for main- taining stability, resistance, and restoration of such ecosys- tems under external influence. MATERIALS AND METHODS Generally, grassland edificators (or their sinusia), creating Study area. The present study was carried out in wet mead- and defining the microenvironment conditions depend at the ows of Nizhne-Svirsky Nature Reserve, Leningrad Region, first on the mode of local environment (i.e. not dependent Russia (border of southern and middle taiga). The investi- on plant communities) factors. In contrast to the edificators gated extensive meadow is located on the ancient the development of the associated plant species (their abun- lake-glacial terrace of Ladoga Lake. These meadows were dance and composition) in the grasslands is controlled by initially formed at the expense of coniferous forests; before the microenvironment that was generated by the edificators 1980, when the Reserve was established, they were used for (Kurkin, 1976; 1998). Peach and Zedler (2006) in the study hay collection and grazing. Since the protected regime, dur- of wet flooded sedge grassland showed that tussocks of ing the 50-year period, the meadow has not been subject to Carex stricta

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