Fire is a natural disturbance occurring every few years in many grasslands ecosystems. However, since European colonization, fire has been highly reduced or even suppressed in Argentinean grasslands, fostering ignitab...Fire is a natural disturbance occurring every few years in many grasslands ecosystems. However, since European colonization, fire has been highly reduced or even suppressed in Argentinean grasslands, fostering ignitable material accumulation. This has led to occasional catastrophic controldemanding fire events, extended for larger areas. The aims of this work are to study vegetation recovery and change after a non-natural fire event in mountain grasslands. The study area is located in the Ventania mountain system, mid-eastern Argentina. We studied vegetation recovery after fire(January 2014) in two different communities: grass-steppes(grasslands) and shrub-steppes(open low shrublands). We measured vegetation cover, species richness and bare ground percentage in burned and unburned areas 1, 4, 8, 11 and 23 months after fire. Vegetation surveys were also performed at the end of the growing season(December) 11 and 23 months after fire. Data were analyzed using regression analysis, ANOVA and multivariate analysis(NMS, PERMANOVA). Both communities increased their vegetation cover at the same rate, without differences between burned and unburned areas after two years. Species richness was higher in shrublands and their recovery was alsofaster than in grasslands. Considering functional composition, besides transient changes during the first year after fire, there were no differences in abundance of different functional vegetation groups two years after fire. At the same time, shrublands showed no differences in species composition, while grasslands had a different species composition in burned and unburned plots. Also, burned grassland showed a higher species richness than unburned grassland. Data shown mountain vegetation in Pampas grassland is adapted to fire, recovering cover and richness rapidly after fire and thus reducing soil erosion risks. Vegetation in mountain Pampas seems to be well adapted to fire, but in grasslands species composition has changed due to fire. Nonetheless, these changes seem to be not permanent since prefire species are still present in the area.展开更多
Aims We aimed to improve the understanding of the carbon and nutri-ent physiological responses and adaptation of semi-arid grassland plants to environmental changes.Methods We investigated plant leaf non-structural ca...Aims We aimed to improve the understanding of the carbon and nutri-ent physiological responses and adaptation of semi-arid grassland plants to environmental changes.Methods We investigated plant leaf non-structural carbohydrate(NSC=solu-ble sugars+starch),nitrogen(N)and phosphorus(P)levels in an Inner Mongolian semi-arid grassland community treated with water,N and P additions for 8 years.Two dominant grasses(Agropyron cris-tatum(L.)Gaertn.,Stipa krylovii Roshev.)and two forbs(Artemisia frigida Willd.,Potentilla bifurca L.)were analyzed.Important Findings Water addition decreased plant leaf N and P concentrations,whereas N and P addition increased them,indicating that the semi-arid grassland studied suffers from a shortage of N and P sup-ply.Both N and P addition decreased the levels of soluble sugars,starch and thus also NSC in plant leaves,which may be attributed to(i)increased carbohydrate consumption associated with a higher growth rate,and(ii)a dilution effect of greater plant size under N and P addition.Water addition tended to increase the leaf NSC levels both in the grasses(+9.2%)and forbs(+0.6%only),which may be a result of increased photosynthesis of plants with increased water availability.Under conditions of ambient and increased water supply in the present study,N addition resulted in an N/P ratio of>16 in the grasses but a significantly lower N/P ratio of<11 in the forb species.This finding implies that growth of the two grass spe-cies will be limited mainly by P availability but the forbs will still be mainly limited by N supply if N deposition,alone or in combination with summer precipitation,continues to increase as predicted in Inner Mongolia.展开更多
Aims and Methods Mostly due to land use changes,European heathlands have become increasingly rare.In addition,the increasing amount of atmospheric nitrogen deposition has resulted in an encroachment of grasses and a l...Aims and Methods Mostly due to land use changes,European heathlands have become increasingly rare.In addition,the increasing amount of atmospheric nitrogen deposition has resulted in an encroachment of grasses and a loss in species diversity.Despite many investigations,information about the precise environmental parameters that determine the development and maintenance of heathland vegetation is still insufficient.In order to determine the environmental factors that control heath succession and grass encroachment,and to develop appropriate management schemes,we studied the influence of several soil and microclimate parameters on species composition and vegetation characteristics in five successional stages in a coastal heathland on the island of Hiddensee,north-east Germany,where the encroachment of Carex arenaria has become a major problem.Important Findings We recorded the highest plant species richness in grey dune and birch forest plots,while the encroachment of C.arenaria let to a significant decline in plant species richness.The most important environmental factors influencing species richness and distribution of single species were microclimate,soil moisture,soil pH and the C/N ratio.While many studies reported the importance of differences in nutrient availability,we found no significant correlations between soil nutrient availability and vegetation pattern.Environmental conditions in dense C.arenaria stands,especially soil properties(e.g.soil pH),showed great differences in comparison to the other successional stages.However,no correlations between the encroachment of C.arenaria and single environmental factors were found.Our results show that not only soil nutrients are important abiotic factors in heaths but that also microclimate and soil moisture play an important role and that many factors are involved in heath succession and in the promotion of grass encroachment.Management plans for the conservation and restoration of heathlands should therefore focus on the specific site conditions and should take several abiotic and biotic factors into account.展开更多
基金supported by the ANPCyT under grant PICT 2014-0865CONICET and Universidad Nacional del Sur from Argentina
文摘Fire is a natural disturbance occurring every few years in many grasslands ecosystems. However, since European colonization, fire has been highly reduced or even suppressed in Argentinean grasslands, fostering ignitable material accumulation. This has led to occasional catastrophic controldemanding fire events, extended for larger areas. The aims of this work are to study vegetation recovery and change after a non-natural fire event in mountain grasslands. The study area is located in the Ventania mountain system, mid-eastern Argentina. We studied vegetation recovery after fire(January 2014) in two different communities: grass-steppes(grasslands) and shrub-steppes(open low shrublands). We measured vegetation cover, species richness and bare ground percentage in burned and unburned areas 1, 4, 8, 11 and 23 months after fire. Vegetation surveys were also performed at the end of the growing season(December) 11 and 23 months after fire. Data were analyzed using regression analysis, ANOVA and multivariate analysis(NMS, PERMANOVA). Both communities increased their vegetation cover at the same rate, without differences between burned and unburned areas after two years. Species richness was higher in shrublands and their recovery was alsofaster than in grasslands. Considering functional composition, besides transient changes during the first year after fire, there were no differences in abundance of different functional vegetation groups two years after fire. At the same time, shrublands showed no differences in species composition, while grasslands had a different species composition in burned and unburned plots. Also, burned grassland showed a higher species richness than unburned grassland. Data shown mountain vegetation in Pampas grassland is adapted to fire, recovering cover and richness rapidly after fire and thus reducing soil erosion risks. Vegetation in mountain Pampas seems to be well adapted to fire, but in grasslands species composition has changed due to fire. Nonetheless, these changes seem to be not permanent since prefire species are still present in the area.
基金The National Natural Science Foundation of China(41371076,31370009)the National Key Basic Research Program of China(2011CB403204)the State Key Laboratory of Forest and Soil Ecology(LFSE2013-01).
文摘Aims We aimed to improve the understanding of the carbon and nutri-ent physiological responses and adaptation of semi-arid grassland plants to environmental changes.Methods We investigated plant leaf non-structural carbohydrate(NSC=solu-ble sugars+starch),nitrogen(N)and phosphorus(P)levels in an Inner Mongolian semi-arid grassland community treated with water,N and P additions for 8 years.Two dominant grasses(Agropyron cris-tatum(L.)Gaertn.,Stipa krylovii Roshev.)and two forbs(Artemisia frigida Willd.,Potentilla bifurca L.)were analyzed.Important Findings Water addition decreased plant leaf N and P concentrations,whereas N and P addition increased them,indicating that the semi-arid grassland studied suffers from a shortage of N and P sup-ply.Both N and P addition decreased the levels of soluble sugars,starch and thus also NSC in plant leaves,which may be attributed to(i)increased carbohydrate consumption associated with a higher growth rate,and(ii)a dilution effect of greater plant size under N and P addition.Water addition tended to increase the leaf NSC levels both in the grasses(+9.2%)and forbs(+0.6%only),which may be a result of increased photosynthesis of plants with increased water availability.Under conditions of ambient and increased water supply in the present study,N addition resulted in an N/P ratio of>16 in the grasses but a significantly lower N/P ratio of<11 in the forb species.This finding implies that growth of the two grass spe-cies will be limited mainly by P availability but the forbs will still be mainly limited by N supply if N deposition,alone or in combination with summer precipitation,continues to increase as predicted in Inner Mongolia.
基金Bauer-Hollmann Foundation within the Stifterverband fu¨r die Deutsche Wissenschaft.
文摘Aims and Methods Mostly due to land use changes,European heathlands have become increasingly rare.In addition,the increasing amount of atmospheric nitrogen deposition has resulted in an encroachment of grasses and a loss in species diversity.Despite many investigations,information about the precise environmental parameters that determine the development and maintenance of heathland vegetation is still insufficient.In order to determine the environmental factors that control heath succession and grass encroachment,and to develop appropriate management schemes,we studied the influence of several soil and microclimate parameters on species composition and vegetation characteristics in five successional stages in a coastal heathland on the island of Hiddensee,north-east Germany,where the encroachment of Carex arenaria has become a major problem.Important Findings We recorded the highest plant species richness in grey dune and birch forest plots,while the encroachment of C.arenaria let to a significant decline in plant species richness.The most important environmental factors influencing species richness and distribution of single species were microclimate,soil moisture,soil pH and the C/N ratio.While many studies reported the importance of differences in nutrient availability,we found no significant correlations between soil nutrient availability and vegetation pattern.Environmental conditions in dense C.arenaria stands,especially soil properties(e.g.soil pH),showed great differences in comparison to the other successional stages.However,no correlations between the encroachment of C.arenaria and single environmental factors were found.Our results show that not only soil nutrients are important abiotic factors in heaths but that also microclimate and soil moisture play an important role and that many factors are involved in heath succession and in the promotion of grass encroachment.Management plans for the conservation and restoration of heathlands should therefore focus on the specific site conditions and should take several abiotic and biotic factors into account.
