Aims Fire has important consequences on vegetation dynamics.In fire-prone areas,natural selection favors plant species,characterized by a large soil seed bank,and that their germination is stimu-lated by fire.Although...Aims Fire has important consequences on vegetation dynamics.In fire-prone areas,natural selection favors plant species,characterized by a large soil seed bank,and that their germination is stimu-lated by fire.Although seed germination stimulated by fire heat is common in the eastern Mediterranean Basin,only little is known about germination stimulation by smoke.We examined the inter-active effect of aerosol smoke and fire history on the germina-ble soil seed bank(GSSB)community in eastern Mediterranean woodlands.Methods We collected soil samples from sites that have been subjected to different fire frequencies during the last four decades and exposed them to aerosol smoke,with or without watering.By document-ing the seed germination patterns characterizing these samples,we could test for changes in the abundance and richness of the germi-nable seeds in the soil.Important Findings Total GSSB density was higher in sites that were burned more fre-quently during the last four decades.Exposure to aerosol smoke increased the GSSB density,and this pattern was more pronounced in samples originating from sites burned more frequently,as well as among annual species.Notably,exposing wet samples to aerosol smoke caused a significant reduction in GSSB density and richness.These results highlight the importance of exploring germination responses using intact soil samples,rather than synthetic seed com-munities.Moreover,our findings emphasize the important role smoke plays in shaping post-fire succession processes in the Mediterranean Basin,mainly by stimulating the germination of annual species.展开更多
We explored if and how seasonal fires interact with microhabitat type(i.e.under Pistacia shrub,under Cistus shrub or a canopy gap)to influence the composition of the germinable soil seed bank(GSSB)community in a typic...We explored if and how seasonal fires interact with microhabitat type(i.e.under Pistacia shrub,under Cistus shrub or a canopy gap)to influence the composition of the germinable soil seed bank(GSSB)community in a typical eastern Mediterranean woodland.We conducted a field experiment,involving prescribed spring and autumn burns,and thereafter quantified the seed germination patterns using soil samples collected from both burned and adjacent unburned control plots.Soil temperature was significantly higher during autumn burns,while being more variable during spring burns.Fire caused overall reductions in GSSB density,richness and diversity.The reductions in GSSB richness and diversity were significantly stronger under Pistacia and Cistus shrubs located within plots subjected to autumn burns,and these patterns were mainly evident among annuals.GSSB density of dwarf shrubs was higher in samples collected from burned plots,and this pattern was more pronounced in samples collected under Pistacia and Cistus shrubs.Together with the appearance of unique species,seasonal fires led to significant changes in the composition of the GSSB community.Our results illustrate that seasonal fires interact with spatial heterogeneity to influence the composition of the GSSB community mostly via differential effects on the germination densities of annuals and dwarf shrubs.These findings imply that the increase in the frequency of seasonal fires,which has occurred in the eastern Mediterranean basin during the last few decades,may translate into a shift in eco-evolutionary selection pressures,operating on plants inhabiting this unique ecosystem.展开更多
基金This research was co-supported by the United States-Israel Binational Science Foundation(BSF Grant 2012081).
文摘Aims Fire has important consequences on vegetation dynamics.In fire-prone areas,natural selection favors plant species,characterized by a large soil seed bank,and that their germination is stimu-lated by fire.Although seed germination stimulated by fire heat is common in the eastern Mediterranean Basin,only little is known about germination stimulation by smoke.We examined the inter-active effect of aerosol smoke and fire history on the germina-ble soil seed bank(GSSB)community in eastern Mediterranean woodlands.Methods We collected soil samples from sites that have been subjected to different fire frequencies during the last four decades and exposed them to aerosol smoke,with or without watering.By document-ing the seed germination patterns characterizing these samples,we could test for changes in the abundance and richness of the germi-nable seeds in the soil.Important Findings Total GSSB density was higher in sites that were burned more fre-quently during the last four decades.Exposure to aerosol smoke increased the GSSB density,and this pattern was more pronounced in samples originating from sites burned more frequently,as well as among annual species.Notably,exposing wet samples to aerosol smoke caused a significant reduction in GSSB density and richness.These results highlight the importance of exploring germination responses using intact soil samples,rather than synthetic seed com-munities.Moreover,our findings emphasize the important role smoke plays in shaping post-fire succession processes in the Mediterranean Basin,mainly by stimulating the germination of annual species.
基金supported by the United States-Israel Binational Science Foundation(BSF Grant 2012081).
文摘We explored if and how seasonal fires interact with microhabitat type(i.e.under Pistacia shrub,under Cistus shrub or a canopy gap)to influence the composition of the germinable soil seed bank(GSSB)community in a typical eastern Mediterranean woodland.We conducted a field experiment,involving prescribed spring and autumn burns,and thereafter quantified the seed germination patterns using soil samples collected from both burned and adjacent unburned control plots.Soil temperature was significantly higher during autumn burns,while being more variable during spring burns.Fire caused overall reductions in GSSB density,richness and diversity.The reductions in GSSB richness and diversity were significantly stronger under Pistacia and Cistus shrubs located within plots subjected to autumn burns,and these patterns were mainly evident among annuals.GSSB density of dwarf shrubs was higher in samples collected from burned plots,and this pattern was more pronounced in samples collected under Pistacia and Cistus shrubs.Together with the appearance of unique species,seasonal fires led to significant changes in the composition of the GSSB community.Our results illustrate that seasonal fires interact with spatial heterogeneity to influence the composition of the GSSB community mostly via differential effects on the germination densities of annuals and dwarf shrubs.These findings imply that the increase in the frequency of seasonal fires,which has occurred in the eastern Mediterranean basin during the last few decades,may translate into a shift in eco-evolutionary selection pressures,operating on plants inhabiting this unique ecosystem.
