Severe effects of long-term drought on calcareous grassland seed banks

Abstract

Climate change models project shifts in precipitation patterns at regional and global scales. Increases in dry areas and the occurrence of drought predicted in future scenarios are likely to threaten grassland ecosystems. Calcareous grassland seed banks have proven to be resistant to short-term drought, but their responses to long-term drought are unknown. Here we show that 14 years of summer drought changed calcareous grassland seed bank composition, reducing its size and richness, and that these responses do not simply reflect patterns in the above-ground vegetation. Moreover, the effect of drought was larger on seed banks than on vegetation, and above-ground responses mediated by soil depth were less evident in the seed bank than in the vegetation. These results demonstrate that the severity of drought effects on calcareous grasslands is larger than previously thought, and show that this ecosystem is highly vulnerable and has low resilience to predicted decreases in soil moisture.

The soil seed bank can buffer long‐term compositional changes in annual plant communities

“…For example, the high drought sensitivity of the vegetation in Californian grasslands was attributed to a depleted seed bank (Harrison et al, 2018). Furthermore, it has been-shown that drought and nitrogen deposition deplete seed banks in several grasslands (Basto et al, 2015(Basto et al, , 2018. Conversely, the high stability of Middle-Eastern annual communities to grazing and rainfall changes was attributed to the high resistance of their seed bank to these environmental factors (Sternberg et al, 2003;Sternberg et al, 2017;Tielborger et al, 2014).…”

Buffering effects of soil seed banks on plant community composition in response to land use and climate

“…Depletion of seed banks has been observed in response to nitrogen deposition (Basto et al., 2015), land‐use change (due to e.g. cessation of management, Plue & Cousins, 2018), as well as climate change in the form of changing rainfall patterns (Basto et al., 2018) and increased temperatures (Ooi et al., 2009). This depletion occurs both directly via effects on seed production and seed bank replenishment, and indirectly via changes in soil chemistry, moisture and temperature regimes.…”

Precipitation and nitrogen addition enhance biomass allocation to aboveground in an alpine steppe

“…Human activity‐induced climate change, especially in part due to shifts in precipitation patterns, and enhanced emission of biological reactive nitrogen (N) to the atmosphere have had profound impacts on the global water and N cycle (Basto et al, ; Stevens, ; Yu et al, ). As water and N are the most important factors that determine the growth and survival of plant and limit the production of grassland ecosystems (Bobbink et al, ; Greaver et al, ), the altered Precip and enhanced N deposition affect grassland ecosystem functions and services that are essential for well‐being of humanity (Basto et al, ; Liu et al, ).…”

“…Human activity‐induced climate change, especially in part due to shifts in precipitation patterns, and enhanced emission of biological reactive nitrogen (N) to the atmosphere have had profound impacts on the global water and N cycle (Basto et al, ; Stevens, ; Yu et al, ). As water and N are the most important factors that determine the growth and survival of plant and limit the production of grassland ecosystems (Bobbink et al, ; Greaver et al, ), the altered Precip and enhanced N deposition affect grassland ecosystem functions and services that are essential for well‐being of humanity (Basto et al, ; Liu et al, ). Despite numerous reports on the effects of altered Precip and enhanced N deposition grassland ecosystems (Liu et al, ; Ma et al, ; Tian et al, ; Yang et al, ), less is known with respect to how altered Precip, enhanced N deposition, and their interaction in the alpine steppe will influence aboveground and belowground biomass allocation, especially at different soil layer (Liu et al, ).…”