Seed survival for three decades under thick tephra

Abstract

Seed longevity in situ is a prerequisite for understanding the life histories and community dynamics of species, although long-term longevity under thick tephra has not been documented because of a lack of opportunity and/or awareness. The seed bank for this study was estimated by both germination and flotation tests. Seeds of 17 species have survived with high density, having been buried under thick tephra for 30 years, since the 1977 -1978 eruptions on Mount Usu, Hokkaido Island, northern Japan. The total seed density was . 1000/m 2 . Rumex obtusifolius was the most common seed-bank species for 30 years, but decreased in density between 20 and 30 years. More seeds of Hypericum erectum occurred in deeper soil. The total seed density decreased gradually for 30 years, but H. erectum and Juncus effusus did not decline. Native seeds tended to be viable longer than exotic seeds. These results suggest that small, native seeds tend to survive longer with deep burial, while the more numerous weedy, exotic seeds located at the soil surface declined faster. The seed bank provides longterm monitoring of seed survival under natural conditions, and could be used to detect genetic changes.

Production, size, and germination of broad‐leaved dock seeds collected from mother plants grown under different nitrogen, phosphorus, and potassium supplies

“…2010). The main reason for its worldwide distribution is the high production of well‐germinable seeds that can survive in the soil seed bank for decades (Toole & Brown 1946; Tsuyuzaki 2010). According to Cavers and Harper (1964), the maximal annual seed production could be 60 000 seeds per plant.…”

Storage on Maternal Plants Affects Temperature Requirements during Germination in Rumex obtusifolius

“…Possible reasons for this longevity include that there were few predators, that seed removal by erosion or animal vector was rare, and that there was minimal competing vegetation. A later study 20 years after the eruption found a seed bank of at least 25 species with 2000 seeds per square meter, in which the dominant species was the non-native R. obtusifolius [29]. The study found a significantly positive correlation between R. obtusifolius seed viability and burial depth, suggesting that seed burial was protective over this time scale.…”

“…From 20 to 30 years after the eruptions, species richness decreased based on the count model but increased according to the zero-hurdle model. The total seed number decreased over time, and R. obtusifolius seed density decreased, but seed frequency did not change [29]. Seedling emergence of R. obtusifolius requires burial at 8 cm or above, and seed dormancy is broken when the seed is exposed to temperatures above 20 • C for a few days [29].…”

Vegetation changes from 1984 to 2008 on Mount Usu, northern Japan, after the 1977–1978 eruptions

“…The origins of plants were classified into two, as either seedbank or nonseedbank because the seedbank greatly contributed the revegetation in the early stages. Seedbank species were determined by the extraction of seeds from the former topsoil and seed germination using the former topsoil (Tsuyuzaki ; Ishikawa‐Goto & Tsuyuzaki, ). All the analyses were conducted by the software package R (version 3.5.0) (R Foundation for Statistical Computing, Vienna, Austria).…”

“…Stochastic events can limit the convergence of vegetation, as demonstrated on Mount St. Helens (del Moral, 2007, 2010, and deterministic assembly rules were not prominent (del Moral and Titus, 2018).…”