Aims and Methods Disturbance is supposed to play an important role for biodiversity and ecosystem stability as described by the intermediate disturbance hypoth-esis(IDH),which predicts highest species richness at inte...Aims and Methods Disturbance is supposed to play an important role for biodiversity and ecosystem stability as described by the intermediate disturbance hypoth-esis(IDH),which predicts highest species richness at intermediate levels of disturbances.In this study,we tested the effects of artificial soil distur-bances on diversity of annual and perennial vascular plants and bryo-phytes in a field experiment in 86 agricultural grasslands differing in land use in two regions of Germany.On each grassland,we implemented four treatments:three treatments differing in application time of soil dis-turbances and one control.One year after experimental disturbance,we recorded vegetation and measured biomass productivity and bare ground.We analysed the disturbance response taking effects of region and land-use-accompanied disturbance regimes into account.Important Findings Region and land-use type strongly determined plant species rich-ness.Experimental disturbances had small positive effects on the species richness of annuals,but none on perennials or bryophytes.Bare ground was positively related to species richness of bryophytes.However,exceeding the creation of 12%bare ground further distur-bance had a detrimental effect on bryophyte species richness,which corresponds to the IDH.As biomass productivity was unaffected by disturbance our results indicate that the disturbance effect on spe-cies richness of annuals was not due to decreased overall produc-tivity,but rather due to short-term lowered inter-and intraspecific competition at the newly created microsites.Generally,our results highlight the importance of soil disturbances for species richness of annual plants and bryophytes in agricultural grasslands.However,most grasslands were disturbed naturally or by land-use practices and our additional experimental soil dis-turbances only had a small short-term effect.Overall,total plant diversity in grasslands seemed to be more limited by the availabil-ity of propagules rather than by suitable microsites for germination.Thus,nature conservation efforts to increase grassland diversity should focus on overcoming propagule limitation,for instance by additional sowing of seeds,while the creation of additional open patches by disturbance might only be appropriate where natural disturbances are scarce.展开更多
Aims The relationship between biodiversity and ecosystem functioning is among the most active areas of ecological research.Furthermore,enhancing the diversity of degraded ecosystems is a major goal in applied restorat...Aims The relationship between biodiversity and ecosystem functioning is among the most active areas of ecological research.Furthermore,enhancing the diversity of degraded ecosystems is a major goal in applied restoration ecology.In grasslands,many species may be locally absent due to dispersal or microsite limitation and may therefore profit from mechanical disturbance of the resident vegeta-tion.We established a seed addition and disturbance experiment across several grassland sites of different land use to test whether plant diversity can be increased in these grasslands.Additionally,the experiment will allow us testing the consequences of increased plant diversity for ecosystem processes and for the diversity of other taxa in real-world ecosystems.Here,we present details of the experimen-tal design and report results from the first vegetation survey 1 year after disturbance and seed addition.Moreover,we tested whether the effects of seed addition and disturbance varied among grassland depending on their land use or pre-disturbance plant diversity.Methods A full-factorial experiment was installed in 73 grasslands in three regions across Germany.Grasslands were under regular agricul-tural use,but varied in the type and the intensity of management,thereby representing the range of management typical for large parts of Central Europe.The disturbance treatment consisted of disturbing the top 10 cm of the sward using a rotavator or rotary harrow.Seed addition consisted of sowing a high-diversity seed mixture of regional plant species.These species were all regionally present,but often locally absent,depending on the resident vegetation composi-tion and richness of each grassland.Important Findings Seven months after sward disturbance,respective plots had significantly increased in bare soil,seedling species richness and number of seed-lings.Seed addition had increased plant species richness,but only in combination with sward disturbance.The increase in species richness,when both seed addition and disturbance was applied,was higher at high land-use intensity and low resident diversity.Thus,we show that at least the early recruitment of many species is possible also at high land-use intensity,indicating the potential to restore and enhance bio-diversity of species-poor agricultural grasslands.Our newly established experiment provides a unique platform for broad-scale research on the land-use dependence of future trajectories of vegetation diversity and composition and their effects on ecosystem functioning.展开更多
基金The DFG Priority Program 1374“Infrastructure-Biodiversity-Exploratories”(FI 1246/6-1,FI 1246/9-1,HO 3830/2-1)of the German Research Foundationthe Potsdam Graduate School of University Potsdam.
文摘Aims and Methods Disturbance is supposed to play an important role for biodiversity and ecosystem stability as described by the intermediate disturbance hypoth-esis(IDH),which predicts highest species richness at intermediate levels of disturbances.In this study,we tested the effects of artificial soil distur-bances on diversity of annual and perennial vascular plants and bryo-phytes in a field experiment in 86 agricultural grasslands differing in land use in two regions of Germany.On each grassland,we implemented four treatments:three treatments differing in application time of soil dis-turbances and one control.One year after experimental disturbance,we recorded vegetation and measured biomass productivity and bare ground.We analysed the disturbance response taking effects of region and land-use-accompanied disturbance regimes into account.Important Findings Region and land-use type strongly determined plant species rich-ness.Experimental disturbances had small positive effects on the species richness of annuals,but none on perennials or bryophytes.Bare ground was positively related to species richness of bryophytes.However,exceeding the creation of 12%bare ground further distur-bance had a detrimental effect on bryophyte species richness,which corresponds to the IDH.As biomass productivity was unaffected by disturbance our results indicate that the disturbance effect on spe-cies richness of annuals was not due to decreased overall produc-tivity,but rather due to short-term lowered inter-and intraspecific competition at the newly created microsites.Generally,our results highlight the importance of soil disturbances for species richness of annual plants and bryophytes in agricultural grasslands.However,most grasslands were disturbed naturally or by land-use practices and our additional experimental soil dis-turbances only had a small short-term effect.Overall,total plant diversity in grasslands seemed to be more limited by the availabil-ity of propagules rather than by suitable microsites for germination.Thus,nature conservation efforts to increase grassland diversity should focus on overcoming propagule limitation,for instance by additional sowing of seeds,while the creation of additional open patches by disturbance might only be appropriate where natural disturbances are scarce.
基金German Research Foundation(DFG)Priority Program 1374‘Infrastructure-Biodiversity-Exploratories’(HO 3830/2-3FI 1246/15-2).
文摘Aims The relationship between biodiversity and ecosystem functioning is among the most active areas of ecological research.Furthermore,enhancing the diversity of degraded ecosystems is a major goal in applied restoration ecology.In grasslands,many species may be locally absent due to dispersal or microsite limitation and may therefore profit from mechanical disturbance of the resident vegeta-tion.We established a seed addition and disturbance experiment across several grassland sites of different land use to test whether plant diversity can be increased in these grasslands.Additionally,the experiment will allow us testing the consequences of increased plant diversity for ecosystem processes and for the diversity of other taxa in real-world ecosystems.Here,we present details of the experimen-tal design and report results from the first vegetation survey 1 year after disturbance and seed addition.Moreover,we tested whether the effects of seed addition and disturbance varied among grassland depending on their land use or pre-disturbance plant diversity.Methods A full-factorial experiment was installed in 73 grasslands in three regions across Germany.Grasslands were under regular agricul-tural use,but varied in the type and the intensity of management,thereby representing the range of management typical for large parts of Central Europe.The disturbance treatment consisted of disturbing the top 10 cm of the sward using a rotavator or rotary harrow.Seed addition consisted of sowing a high-diversity seed mixture of regional plant species.These species were all regionally present,but often locally absent,depending on the resident vegetation composi-tion and richness of each grassland.Important Findings Seven months after sward disturbance,respective plots had significantly increased in bare soil,seedling species richness and number of seed-lings.Seed addition had increased plant species richness,but only in combination with sward disturbance.The increase in species richness,when both seed addition and disturbance was applied,was higher at high land-use intensity and low resident diversity.Thus,we show that at least the early recruitment of many species is possible also at high land-use intensity,indicating the potential to restore and enhance bio-diversity of species-poor agricultural grasslands.Our newly established experiment provides a unique platform for broad-scale research on the land-use dependence of future trajectories of vegetation diversity and composition and their effects on ecosystem functioning.
