Nonlinear response of the soil seed bank and its role in plant community regeneration with increased grazing disturbance

Abstract

The soil seed bank represents valuable rebuilding capital that may rescue an ecosystem from state transition once vegetation has crossed an apparent threshold from the desired to degraded state. However, almost no research has explored the response of transient and persistent seed banks and their role in plant community regeneration along a gradient of wetlands from intact to a seriously degraded state due to increased grazing disturbance. Seven grazing disturbance levels from nondisturbed to highly degraded alpine marsh ecosystems were selected on the eastern Tibetan Plateau. Akaike information criterion (AIC) was used to select the best‐fit model to predict the response of the plant community, soil seed bank and Bray–Curtis dissimilarity index to increased grazing disturbance. Both the plant community and seed bank showed a nonlinear change with increasing grazing disturbance. Species richness and seed density of the transient seed bank first decreased and then increased with increased disturbance, but the persistent seed bank showed a reverse trend, with an obvious threshold. Species composition of the persistent and transient seed banks exhibited little change compared to the plant community as disturbance increased. Similarities between both the persistent and transient seed banks and plant community also showed a nonlinear change with increased disturbance, while the persistent seed bank had a higher similarity with the plant community than the transient seed bank. Synthesis: At high grazing disturbance, persistent seed banks are more important than transient seed banks in plant community regeneration. Alpine wetland ecosystems have intrinsic resilience because the persistent seed bank has a pool of species above the threshold. However, ecosystem resilience declines if the species pool of the persistent seed bank is depleted below the threshold. The restoration potential of the seed bank has limits, and it will gradually be exhausted when species losses due to increased grazing intensity exceed the threshold of state transition.

A Before‐After Control‐Impact experiment reveals that culling reduces the impacts of invasive deer on endangered peatlands

“…A Control–Impact design could have mistakenly provided support for a beneficial treatment effect when none, in fact, occurred. Control–Impact designs are used for a posteriori comparison of management in applied ecology (An et al, 2022; Reed et al, 2022). Additionally, for half of the impacts that changed across all experimental units (i.e.…”

Light controls alpine meadow community assembly during succession by affecting species recruitment from the seed bank

“…The seedling emergence period was from May to October 2015, which is the growing season for the eastern part of the Tibetan Plateau. All trays were watered several times each day to keep the soil moist (An et al, 2022; Ma et al, 2009). In order to favor maximum germination, emerging seedlings were identified, recorded and removed to keep a low seedling density in each tray.…”

“…Germinating seedlings were monitored daily during the first 2 months of the study and weekly for the next 3 months. Seedlings that could not be identified were grown separately until they could be identified (An et al, 2022; Ma et al, 2020). The soil samples were stirred after 2 months following cessation of the initial flush of germinating seeds in order to expose the nongerminated seeds (Ma et al, 2009).…”

“…All soil samples were transported to the Gannan Grassland Ecosystem National Observation and Research Station‐Hezuo branch, where they were placed on a table in front of a north‐facing window for 15 days to allow them to dry (An et al, 2022; Ma et al, 2020). Then, each sample was sieved to remove root fragments and coarse debris, after which it was sieved through a coarse (0.4 mm mesh) and then through a fine (0.2 mm) sieve.…”

Seed Viability, Spikelet Dispersal, Seed Banks and Seed Storage Requirements for Native and Invasive Cordgrasses (Genus Spartina) in Southwest Iberian Peninsula

“…Soil seed banks play an important role in the establishment, maintenance, regeneration and restoration of vegetation in many plant communities (Bao et al 2021;An et al 2022). In salt marshes, seed dispersal and soil seed banks play an important role in determining the spatial and temporal distribution of halophytes (Egan and Ungar 2000;Rand 2000;Crain et al 2008), and the successional assembly of halophytic communities following disturbance or restoration actions (Dausse et al 2007;Kottler and Gedan 2019).…”