Plant dispersal strategies in primary succession on the Tolbachinsky Dol volcanic Plateau (Russia)

By Anton Korablev, Vadim Smirnov, Valentina Neshataeva, Igor Kuzmin & Timofey Nekrasov

Pioneer plants establishing in volcanic ash and scoria fields disturbed by the eruption in 1975, Tolbachinskii Dol Volcanic Plateau, Kamchatka, Russia. (A historical remark: this place could be a point of the field excursion to Kamchatka during 63rd IAVS Symposium in Vladivostok, that has been cancelled due to the COVID-19 pandemic.) Photo credit: Anton Korablev.

The role of volcanic activity on the Globe is hard to exaggerate. Volcanic eruptions affect many processes on our Planet – from a long-term impact on global climate to local changes in edaphic conditions of surrounding habitats. In volcanic regions, eruptions can strongly drive ecosystem functioning, destroying previous habitats and creating completely new sites without any organic matter. To occupy new habitats, plants demonstrate a variety of mechanisms that help them pass through different barriers, distribute their seeds (or spores), and establish in a hostile environment. The patterns of colonization of a recently formed tephra (rough igneous substance) plain by vascular plants were investigated in the poorly studied region on the Kamchatka Peninsula (Russia).

The climate of the district is moderately continental. The surrounding vegetation at altitudes up to 900 m above sea level is formed mainly by larch forests (Larix gmelinii), and at altitudes up to 1900 m by mountain tundra. In 1975–1976, the Tolbachinsky Dol Plateau was the site of the Great Tolbachik Fissure Eruption, which destroyed the vegetation cover on an area of about 170 km2. Soon community assembly processes began in the newly formed habitat. By July 2019, the vegetation cover was unequally developed in different sites, from bare tephra fields (closer to the centre of the plateau) with a scarce plant cover up to dense plant communities near the border of the surviving forest.

The main constraints of the rapid development of vegetation in the devastated area were the instability of tephra, the deficit of nutrients, and the lack of seeds of species that could survive in such extreme conditions. To uncover the patterns of plant community assembly in these unfavourable habitats, we used data from our vegetation studies conducted in 2006–2010. Pioneer vegetation communities in the devastated area at the altitude range of 384–945 m were chosen for the study (54 sample plots in total). To determine the species pool of the surrounding forests, 63 relevés from plant communities that survived the eruption were included in the analysis.

Papaver microcarpum, one of the pioneer species colonizing barren volcanic substrates after the eruption of 1975. Photo credit: Anton Korablev.

The main plant traits that have great importance to overcome the environmental constraints in this area were analyzed. As a dispersal trait, plant dispersal syndrome (the way that plants use to disperse their seeds) was assessed. As establishment traits that help species to survive, plant life-form, root type, the presence of rhizome, and the density of above-ground shoots were analyzed.

As a result, we have shown that on the tephra plain, species without special adaptations to wind dispersal with fairly heavy (>0.05 mg) seeds benefited through the colonization of newly formed habitats, while wind dispersal seeds were blown into natural traps due to strong winds blowing on the smooth surface of tephra deposits. The aerodynamic characteristics of seeds and the turbulent features of habitats (microrelief and the presence of natural seed traps) were important in primary succession, as well as biotic facilitation and environmental conditions. Our results showed that both dispersal and environmental filters interactively shaped the community structure in early succession.

This is a plain language summary for the paper of Korablev et al. published in the Journal of Vegetation Science ( Post prepared by Anton Korablev and Valentina Neshataeva.