Legacy Effects of Extreme Drought on the Belowground Bud Bank of Bunchgrass and Rhizomatous Steppe Communities in Inner Mongolia

Belowground bud banks play a crucial role in plant population regeneration, community dynamics and ecosystem functions in response to environmental change and disturbance. In mesic grasslands, belowground bud banks are largely resistant to short-term drought. The sensitivity of belowground bud banks to long-term extreme drought in semiarid steppes is less understood. Here, we investigated the legacy effects of a 4-year experimental drought (i.e., 66% reduction in growing season precipitation) on belowground bud density, aboveground shoot density and their relationship (represented by the meristem limitation index-MLI) in two temperate semiarid steppes with different dominated plant growth forms (i.e., bunchgrass vs. rhizomatous grass). Measurements were made during the first recovery year following drought; thus, we reported the legacy effects of drought on belowground bud bank. Results showed that at community level the densities of both belowground buds and aboveground shoots decreased while there was no change in MLI. However, drought had no significant influences on belowground buds, aboveground shoots and MLI of the dominant plant growth form. The legacy effects of drought were largely dependent on plant community type and growth form. Specifically, due to their cluster/phalanx clonal growth, bunchgrasses and communities they dominated were characterized by greater meristem limitation compared with rhizomatous grasses. Our study implies that integrating belowground bud bank demography into the predictive model of community dynamics and ecosystem functions in response to climate change should be considered to understand the differing responses among community type and dominant plant groups.

A floristic assessment of grassland diversity loss in South Africa

Background: Land-use effects on grassland flora are difficult to predict due to poor understanding of species losses caused by transformation.Objectives: To determine changes in species diversity and composition by comparing transformed with untransformed grassland.Methods: Floristics of paired plots were sampled within 18 transformed sites (representing agricultural and urban land-uses) and neighbouring untransformed grassland.Results: Endemic and threatened species were negatively affected by transformation, particularly species with belowground bud-banks and storage organs. Species composition, with clear shifts in dominant families, was changed by over 90% on average by transformation.Conclusion: Land-use transformation leads to the loss of native species and increased alien invasive species.

Responses of Plant Bud Bank Characteristics to the Enclosure in Different Desertified Grasslands on the Tibetan Plateau

Asexual reproduction is the main mode of alpine plant reproduction, and buds play an important role in plant community succession. The purpose of this study is to explore whether the desertified grassland can recover itself through the existing bud bank. The bud bank composition, distribution and size of different desertified grasslands were studied using unit volume excavation on the Tibetan Plateau. The bud bank consisted of tiller, long and short rhizome buds, and more than 40% of buds were distributed in the 0–10 cm soil layer. Enclosure changed the bud density, distribution and composition. The bud densities were 4327 and 2681 No./m2 in light and middle desertified grasslands before enclosure, while that decreased to 3833 and 2567 No./m2 after enclosure. Tiller bud density and proportion of middle desertified grassland were the highest, increased from 2765 (31.26%, before enclosure) to 5556 No./m3 (62.67%, after enclosure). There were new grasses growing out in the extreme desertified grassland after enclosure. The meristem limitation index of moderate desertified grassland was the lowest (0.37), indicating that plant renewal was limited by bud bank. Plants constantly adjust the bud bank composition, distribution, and asexual reproduction strategy, and desertified grasslands can recover naturally, relying on their bud banks through an enclosure.

The ecology and significance of below-ground bud banks in plants

BackgroundBelow-ground bud banks have experienced much recent interest due to discoveries that they (1) account for the majority of seasonal population renewal in many communities, (2) are crucial to regeneration following disturbance, and (3) have important consequences for plant population dynamics and plant and ecosystem function across a number of habitats.ScopeThis review presents an overview of the role of bud banks in plant population renewal, examines bud bank life history, summarizes bud bank traits and their potential ecological implications, synthesizes the response of bud banks to disturbance, and highlights gaps to guide future research. The characteristics and life history of buds, including their natality, dormancy, protection and longevity, provide a useful framework for advancing our understanding of bud banks. The fate of buds depends on their age, size, type, location, and biotic and abiotic factors that collectively regulate bud bank dynamics. A bud bank can provide a demographic storage effect stabilizing population dynamics, and also confer resistance to disturbance and invasion. Regeneration capacity following disturbance is determined by interactions among the rates of bud natality, depletion and dormancy (meristem limitation), and the resources available to support the regeneration process. The resulting response of plants and their bud banks to disturbances such as fire, herbivory and anthropogenic sources determines the community’s regenerative capacity.ConclusionsVegetation responses to environmental change may be mediated through changes in bud bank dynamics and phenology. Environmental change that depletes the bud bank or prohibits its formation likely results in a loss of vegetation resilience and plant species diversity. Standardization of bud sampling, examination of bud banks in more ecosystems and their response to environmental variation and disturbance regimes, employment of stage-structured bud bank modelling and evaluation of the cost of bud bank construction and maintenance will benefit this expanding field of research.

Comparison of biomass removal, nutrient manipulation and native seed addition to restore the ground layer of a degraded grassy woodland

This study reports on a trial of methods to overcome barriers to restoration of degraded Cumberland Plain woodland. Soil scalping was compared with fire or slashing to remove existing canopy. Fire and slashing were combined with soil carbon addition at two levels, to reduce soil nitrate. Native seed was added to overcome a lack of native propagules. Treatments, applied to 2 × 2 m plots, consisted of a control; scalped; fire and slash treatments without carbon addition; fire and slash treatments at the low and the high carbon addition levels; and a further fire and a slash treatment at the low carbon level with no native seed added, to give 10 treatments in total. Scalping eliminated the existing canopy and reduced weed seed and bud banks allowing native species (and some colonising exotics) to establish by 33 months. Rapid re-growth in the fire treatment resulted in plant canopy abundance returning to control levels by 12 months, and native species richness on burnt plots remained similar to the control. Canopy abundance in the slash treatment remained lower than in the controls for 20 months, and native species richness increased by then. Carbon addition reduced canopy re-growth in both fire and slash treatments: in the fire-low carbon plots with added native seed, native species richness was double that of the controls by 20 months. This increase did not occur on slash-low carbon plots. The highest level of carbon addition had negative effects on plant growth and survival, resulting in the lowest native species richness. The non-scalping treatments had little effect on exotic species richness in the absence of carbon or small negative effects if combined with carbon.