A study of soil seed banks across one complete chronosequence of secondary succession in a karst landscape

Abstract

Anthropogenic disturbance and distinctive geochemistry have resulted in rocky desertification in many karst regions of the world. Seed banks are crucial to vegetation regeneration in degraded karst ecosystems characterized by a discontinuous distribution of soil and seasonal drought stress. However, the dynamics of seed banks across one complete series of secondary succession and the underlying mechanisms remain unclear. We selected eight typical stages during secondary succession, conducted aboveground vegetation survey and collected 960 soil samples in the Guiyang karst landscape of China. Seed density, species richness and plant life forms in seed banks were determined via the germination method. The results indicated that the seed density in seed banks before and after field seed germination was significantly different among most succession stages. Community succession had impacts on the seed density of seed banks before and after field seed germination. Seed density ranged from 1,042 seedlings.m−2 in evergreen broadleaf forests to 3,755 seedlings.m−2 in the herb community, which was a relatively high density. The seed density and similar species composition between the seed banks and vegetation declined with succession from early to later stages. Species richness in seed banks was highest in middle succession stages and increased with increasing species richness of aboveground vegetation. The species richness of the five life forms in the seed banks showed different variations across these succession stages. The conservation of diverse aboveground vegetation can maintain the diversity of seed banks for restoration.

Invasive species in the soil seed bank of two limestone hills in Bogor, West Java, Indonesia

“…The presence of species in the soil seed banks is affected not only by the aboveground vegetation but also by dispersal mechanism (Rungrojtrakool 2021), which explains why the seed bank in the two study sites was not reflected in the aboveground vegetation. This finding is in line with experiments conducted by He et al (2020) on seed bank in a karst landscape in central Guizhou Province, China.…”

“…Species richness represented by the number of species present in the seed bank of the two sites was relatively high. The number was relatively similar to the results of He et al (2020) obtained in Guiyang karst landscape in China which had approximately 89 species. The number of species in Nyungcung is higher than Kapur hills.…”

“…All of these species were present in the seed bank but not all of the species in the seed bank were present in the aboveground vegetation. The composition dissimilarity of the aboveground vegetation and the seed bank found in many studies indicates that certain number of seed bank diversity is not represented in the aboveground; therefore seed bank species pools did not closely resemble the standing vegetation (Grewell et al 2019;He et al 2020). The high abundance of "new species" which is not yet widespread in the aboveground, often occurs because the "new species" seeds were already present in the seed bank, and become a source of recruitment under favorable conditions (Vandvik et al 2016).…”

Seed germination traits and dormancy classification of 27 species from a degraded karst mountain in central Yunnan–Guizhou Plateau: seed mass and moisture content correlate with germination capacity

“…The different stages of secondary succession are mainly herbaceous community, vine shrubland and a forest-shrubland transition (Fig. 1; He et al 2020).…”

“…Based on our results, nondormant seeds of F. esculentum, O. opipara, P. fortuneana and S. salicifolia had low seed mass (TSM <2.6 g) and moisture content (SMC <5.7%) and high germination capacity. Moreover, most of the studied seeds were pioneer herbs/shrubs in early stages of positive succession, and thus can be used to accelerate succession from bare land to herbaceous community or shrubland, which is the first and crucial step for natural vegetation recovery (Liu et al 2011;He et al 2020). When introducing such wellperformed species into a rocky barren karst area by direct seeding, it is best to sow seeds at beginning of the rainy season, which will stimulate germination and offer the germinated seedlings the maximum amount of time for growth before the dry season starts.…”