Soil erosion is among the critical environmental constraint for crop production in southern Mali. Contour ridge tillage (CRT), a water conservation technique had been locally applied since 1990. The objective of this ...Soil erosion is among the critical environmental constraint for crop production in southern Mali. Contour ridge tillage (CRT), a water conservation technique had been locally applied since 1990. The objective of this study was to determine the effects of CRT compared with farmer conventional agriculture practice (NoCRT) on runoff, soil loss, nutrient loss, moisture conservation and cereals yields under rainfed conditions in two Southern Mali sites, in 2016 and 2017 in farmer fields. Measurements were performed on erosion plots composed of CRT and NoCRT plots from which water samples were collected to determine sedimentation levels, concentration and nutrients losses using pairwise comparison. Average runoff coefficient in NoCRT plots was 35.62% compared to 19.25% for the CRT plots explaining a runoff reduction of 46%. Mean soil losses of 12,095 t·ha-1 and 4970 t·ha-1 were respectively measured in NoCRT and CRT plots. Losses in calcium, magnesium and potassium nutrients in the NoCRT plots were 80%, 66%, 75% higher compared to CRT ones, respectively. Sorghum grain yield was at least two folds higher in CRT plots compared to the NoCRT plots. Maize average grain yield was 87% higher in CRT plots than in the NoCRT. For sustained soil productivity, CRT is advocated as a better soil and water management technique than the NoCRT one.展开更多
Background:Many fire-dependent forests have experienced significant declines in species,structural,and functional diversity.These changes are attributed in part to traditional management approaches that were dominated...Background:Many fire-dependent forests have experienced significant declines in species,structural,and functional diversity.These changes are attributed in part to traditional management approaches that were dominated by even-aged regeneration methods such as clearcutting.Variable retention harvesting(VRH)is an ecologically based forestry practice that involves retention of some mature overstory trees and other biological structures in the postharvest stand to emulate the effects of natural disturbance events.In this study,we examined the effect of a VRH treatment on recruitment of historically dominant pine species and understory vegetation twoand six years after its implementation in a naturally regenerated mixed pine forest in the Upper Peninsula of Michigan,USA.Results:We found greater regeneration of red pine(Pinus resinosa L.)and eastern white pine(Pinus strobus L.)in VRH stands compared to the unharvested controls.Although red pine recruitment was very low during the first 2 years,both species increased significantly from year two to year six.Recruitment responses for the two species did not differ significantly between the aggregated and dispersed retention treatments.We also found high recruitment of deciduous tree species,consisting primarily of sprouts,and red pine exhibited a negative correlation with these sprouts.Treatment,time,and the interaction of treatment and time were significant factors in red pine recruitment.Time had a strong effect on the understory vegetation,with significant decreases in shrubs and ferns over time.Conclusions:The results suggest that VRH enhanced recruitment of red pine and eastern white pine and that this recruitment increased with time.We identify competition from sprouts and unfavorable seedbed conditions as the main factors that limited recruitment of red pine during the first 2 years.To reduce competing vegetation and improve seedbed conditions,we suggest following the VRH with a prescribed fire,mechanically removing sprouts,and implementing herbicide treatments.At a time when changes in global climate exacerbates the effects of traditional drivers of forest degradation,and with the need to maintain biodiversity,new ecologically based forest practices such VRH have the potential to facilitate regeneration of native trees and enhance the resilience of many fire-dependent forests.展开更多
文摘Soil erosion is among the critical environmental constraint for crop production in southern Mali. Contour ridge tillage (CRT), a water conservation technique had been locally applied since 1990. The objective of this study was to determine the effects of CRT compared with farmer conventional agriculture practice (NoCRT) on runoff, soil loss, nutrient loss, moisture conservation and cereals yields under rainfed conditions in two Southern Mali sites, in 2016 and 2017 in farmer fields. Measurements were performed on erosion plots composed of CRT and NoCRT plots from which water samples were collected to determine sedimentation levels, concentration and nutrients losses using pairwise comparison. Average runoff coefficient in NoCRT plots was 35.62% compared to 19.25% for the CRT plots explaining a runoff reduction of 46%. Mean soil losses of 12,095 t·ha-1 and 4970 t·ha-1 were respectively measured in NoCRT and CRT plots. Losses in calcium, magnesium and potassium nutrients in the NoCRT plots were 80%, 66%, 75% higher compared to CRT ones, respectively. Sorghum grain yield was at least two folds higher in CRT plots compared to the NoCRT plots. Maize average grain yield was 87% higher in CRT plots than in the NoCRT. For sustained soil productivity, CRT is advocated as a better soil and water management technique than the NoCRT one.
基金the Joint Fire Science Program(JFSP),The Ohio State University,Seney National Wildlife Refuge(SNWR)Seney Natural History Association.
文摘Background:Many fire-dependent forests have experienced significant declines in species,structural,and functional diversity.These changes are attributed in part to traditional management approaches that were dominated by even-aged regeneration methods such as clearcutting.Variable retention harvesting(VRH)is an ecologically based forestry practice that involves retention of some mature overstory trees and other biological structures in the postharvest stand to emulate the effects of natural disturbance events.In this study,we examined the effect of a VRH treatment on recruitment of historically dominant pine species and understory vegetation twoand six years after its implementation in a naturally regenerated mixed pine forest in the Upper Peninsula of Michigan,USA.Results:We found greater regeneration of red pine(Pinus resinosa L.)and eastern white pine(Pinus strobus L.)in VRH stands compared to the unharvested controls.Although red pine recruitment was very low during the first 2 years,both species increased significantly from year two to year six.Recruitment responses for the two species did not differ significantly between the aggregated and dispersed retention treatments.We also found high recruitment of deciduous tree species,consisting primarily of sprouts,and red pine exhibited a negative correlation with these sprouts.Treatment,time,and the interaction of treatment and time were significant factors in red pine recruitment.Time had a strong effect on the understory vegetation,with significant decreases in shrubs and ferns over time.Conclusions:The results suggest that VRH enhanced recruitment of red pine and eastern white pine and that this recruitment increased with time.We identify competition from sprouts and unfavorable seedbed conditions as the main factors that limited recruitment of red pine during the first 2 years.To reduce competing vegetation and improve seedbed conditions,we suggest following the VRH with a prescribed fire,mechanically removing sprouts,and implementing herbicide treatments.At a time when changes in global climate exacerbates the effects of traditional drivers of forest degradation,and with the need to maintain biodiversity,new ecologically based forest practices such VRH have the potential to facilitate regeneration of native trees and enhance the resilience of many fire-dependent forests.
