AimHigh temperatures during forest fires can cause significant damage to tropical dry forest areas and alter their ecological stability, particularly by affecting seed viability and seedling emergence. This study evaluates the seedling emergence response of 18 dry forest species to fire-simulated temperatures, aiming to assess their potential for restoration in fire-prone Colombian ecosystems.LocationThe seeds used in this study were obtained from three tropical dry forests in Colombia.MethodsA total of 9832 seeds from 18 dry forest species were collected directly from the soil seed bank in three tropical dry forests in Colombia. These seeds were then exposed to simulated forest fire temperatures (100 degrees C, 150 degrees C, and 200 degrees C) for 10 min. Seed viability was analyzed using the 2,3,5-triphenyl tetrazolium chloride reagent (tetrazolium test) and assessed using a generalized linear model. Seedling emergence and mean emergence time were evaluated using one-way analysis of variance (ANOVA) with temperature treatments as factors.ResultsThe study revealed that seedling emergence significantly decreased with higher heat shock temperatures. Notably, Hura crepitans and Parkinsonia aculeata tolerated temperatures up to 100 degrees C, while Caesalpinia pulcherrima and Enterolobium cyclocarpum showed increased emergence at that temperature. Based on their emergence responses, species were classified as stimulated, tolerant, sensitive, or vulnerable. Seed viability declined with rising temperatures, and the mean emergence time increased in species like Cordia alba, Crescentia cujete, and Lonchocarpus violaceus.ConclusionsThis study shows that heat shocks at 150 degrees C and 200 degrees C significantly reduced seed bank viability for most Colombian dry forest species. However, Caesalpinia pulcherrima and Enterolobium cyclocarpum were stimulated by 100 degrees C heat shocks, while Hura crepitans and Parkinsonia aculeata showed no adverse effects. Vulnerable species like Coccoloba acuminata and Pithecellobium dulce exhibited no viable seeds at higher temperatures, suggesting potential local extinctions. These results emphasize the need to focus on heat-tolerant species for restoration efforts in fire-prone ecosystems.

Global change can easily cause the wetland ecosystem structure and function to be damaged by alien species. Former studies on Spartina alterniiora invasion only focused on the effect of aboveground communities, ignoring the potential regeneration of soil seed banks. Therefore, the study aimed to find the key resources that limit the S. alterniiora invasion and the regulation mechanism for S. alterniiora regeneration. Through investigating the S. alterniiora communities with different invasion stages, we studied the structure and composition of the aboveground communities and the soil seed banks, in response to the soil properties and water and nitrogen addition. The dominant competitive advantage of S. alterniiora was mainly affected by the aboveground biomass, which was regulated by soil NH4+-N and moisture content. Although the richness was same in the soil seed banks under the S. alterniiora communities with different coverage, S. alterniiora seeds maintained its specific competitive dominance. The niche breadth of S. alterniiora and the niche overlap between S. alterniiora and Tripolium pannonicum was the highest under low aboveground coverage. The soil seed bank germination experiments showed that the S. alterniiora density decreased when the soil nitrogen concentration exceeded 1 g/ kg, while the density of native species E. crusgalli and T. pannonicum decreased when the water depth above the soil surface exceeded 2 cm. The successful naturalization of S. alterniiora invasion regulated by nitrogen-water coupling is a bet-hedging of the niche and fitness differences between invasive and native species in the coastal salt marsh of eastern China.

We tested the hypothesis that the number of seedlings from the soil seed bank (SSB) in forests polluted by heavy metals and disturbed by recent fires decreases. It was also assumed that the consequences of pollution and fires for the soil seed bank are additive. We estimated the number of seedlings from the SSB of pine forests located near the Karabash copper smelter (KCS) (contaminated by Cu, Zn, Pb, and Cd) and from uncontaminated forests of the Ilmen State Reserve (ISR). In both areas, samples of the forest litter and humus horizon were taken from forests recently exposed to ground fires and long-term unburned forests. Samples were exhibited from June to September, conducting seven rounds of counting seedlings. Small peculiarities of the emergence of seedlings on the samples of the forest litter and the humus horizon were established. However, the regularities of the reaction of SSB to pollution and fire disturbances did not depend on the soil horizon. The number of seedlings on substrates from contaminated forests was 5-8 times lower than the number of seedlings on substrates from background forests. A decrease in the number of seedlings on polluted substrates was accompanied by an increase in the share of dicots in the total number of seedlings. The relationship between the number of seedlings and the age of fires was not found. The additivity of the consequences of pollution and fires has also not been established. Of the two types of damage, pollution and fires, the pollution factor is of leading importance for SSBs. The results indicate a low recovery capacity of the herb-shrub layer of polluted forests.

Background and Aims Seed persistence in soil depends on environmental factors that affect seed dormancy and germination, such as temperature and water availability. In high-elevation ecosystems, rapid changes in these environmental factors because of climate change can impact future plant recruitment. To date, our knowledge on how soil seed banks from high-elevation environments will respond to climate change and extreme climate-related events is limited. Here, using the seedling emergence method, we investigated the effects of reduced snow cover, fire and drought on the density and diversity of germinants from soil seed banks of two high-elevation plant communities: a tall alpine herbfield and a treeline ecotone.Methods In Autumn 2020, we collected soil samples and characterized the standing vegetation of both communities at Kosciuszko National Park, Australia. Subsequently, we carried out a factorial experiment and subjected the soil samples to a series of manipulative treatments using greenhouse studies.Key Results The treeline had a larger and more diverse soil seed bank than the herbfield. A reduction in snow had a negative effect on the number of germinants in the herbfield and increased the dissimilarity with the standing vegetation, whereas the treeline responses were mainly neutral. Fire did not significantly affect the number of germinants but decreased the evenness values in both communities. The drought treatment reduced the number and richness of germinants and increased the dissimilarity with the standing vegetation in both communities. Plant functional forms explained some of the detected effects, but seed functional traits did not.Conclusions Our study suggests that simulated climate change will affect plant recruitment from soil seed banks in a variety of ways. Changes in snow cover and incidences of fire and drought might be key drivers of germination from the soil seed bank and therefore the future composition of alpine plant communities.