The loess plains cover approximately 2000.00 km2 of the northern Negev Desert,accounting for about 9%of Israel's total land area.As elsewhere,the loess in the Negev Desert is composed of wind-transported dust and ...The loess plains cover approximately 2000.00 km2 of the northern Negev Desert,accounting for about 9%of Israel's total land area.As elsewhere,the loess in the Negev Desert is composed of wind-transported dust and sand particles that have been deposited in sink sites.The loess deposits are characteristically covered by biocrusts,which constitute a substantial share of the region's primary productivity.The biocrusts regulate the vascular vegetation communities,including herbaceous and woody plants,many of which are endemic and/or endangered plant species.Throughout history,the region's main land-uses have been based on extensive livestock grazing and runoff-harvesting agriculture,which both still exist to some extent.These land-uses did not challenge the sustainability of the geo-ecosystems over centuries and millennia.At present,predominant land-uses include intensive rangelands(1016.81 km2,encompassing 51%of the loess plains'area),croplands(encompassing both rainfed and irrigated cropping systems:930.92 km2,47%of the loess plains'area),and afforestation lands(158.75 km2).These current land-uses impose substantial challenges to the functioning of the loess plains.Further,urban and rural settlements have expanded considerably in the last decades(158.45 km2),accompanied by mass construction of infrastructures.Altogether,these new land-uses have caused widespread soil erosion,soil structure deformation,depletion of soil organic carbon,environmental contamination,native vegetation removal,invasion of plant species,and habitat fragmentation.Recent climate change has intensified these stressors,exacerbating adverse impacts and forming feedback loops that intensify land degradation and desertification.The declining ecosystem functioning over recent decades emphasizes the urgent need for passive and active restoration schemes.While some of these efforts have proven to be successful,other have failed.Therefore,proactive policy making and environmental legislation are needed to plan and develop schemes aimed at halting land degradation,while simultaneously maximizing nature conservation and restoration of degraded lands across the loess plains.Such actions are expected to increase the regions'capacity for climate change mitigation and adaptation.展开更多
In drylands,biocrusts play crucial roles in regulating ecosystem functions.The study was conducted in the hilly rangelands of the semi-arid northern Negev of Israel,where we assessed the visual,morphological,spectral,...In drylands,biocrusts play crucial roles in regulating ecosystem functions.The study was conducted in the hilly rangelands of the semi-arid northern Negev of Israel,where we assessed the visual,morphological,spectral,and soil properties of livestock trampling routes and inter-route spaces in northern and southern facing hillslopes.Overall,both hillslope aspects were visually similar,whereas the ground surface of the routes was brighter(74.4%were characterized as having a'light'color)than the inter-route spaces(86.8%were characterized as having a'dark'color).These observations were supported by morphological identification of biocrust composition,which was dominated by cyanobacteria(67%)in the routes,and by mixed cyanobacteria/moss(56%)in the inter-routes.Mean Normalized Difference Vegetation Index(NDVI)was 24%higher in the inter-routes,while the mean Brightness Index(BI)was 12%higher in the routes.At the same time,the mean Crust Index(CI)was identical in the two microhabitats.Soil quality index(SQI),calculated based on the(pedoderm)soil properties of the two microhabitats,was 6%greater in the inter-routes than in the routes.This study suggests that recurrent trampling exacerbates soil compaction and shearing along the routes,thus preventing the successional development of complex biocrust compositions.展开更多
Land degradation affects extensive drylands around the world.Due to long-term misuse,the Israeli Sde Zin dryland site has faced severe degradation.The study objective was to assess the feasibility of passive restorati...Land degradation affects extensive drylands around the world.Due to long-term misuse,the Israeli Sde Zin dryland site has faced severe degradation.The study objective was to assess the feasibility of passive restoration in recovering the site.The study was conducted in four land-units along a preservation-degradation continuum:(1)an area that has not faced anthropogenic disturbances(Ecological land);(2)an area that was proclaimed as a national park in the 1970s(Rehabilitation);(3)an area that was prone,until recently,to moderate anthropogenic pressures(Triangle);and(4)a dirt road that was subjected to long-term off-road traffic(Dirtroad).Soil was sampled and analyzed for its properties.The soil physical quality followed the trend of Ecological land>Rehabilitation>Triangle>Dirtroad.Specifically,high soil salinity in the latter three land-units is attributed to long-term erosional processes that exposed the underlying salic horizons.Herbaceous and shrubby vegetation cover was also monitored.The herbaceous vegetation cover followed the trend of Ecological land(86.4%)>Rehabilitation(40.3%)>Triangle(26.2%)>Dirtroad(2.1%),while the shrubby cover was 2.8%in the Ecological land-unit,and practically zero in the other land-units.It seems that despite the effectiveness of passive restoration in recovering the soil’s physical properties,the recovery of vegetation is limited by the severe soil salinity.展开更多
A long-term drought has led to the mass mortality of shrubs in the semi-arid Israeli Negev.The most impacted shrub species is the Noaea mucronata(Forssk.)Asch.and Schweinf.In a four-year study,we found that herbaceous...A long-term drought has led to the mass mortality of shrubs in the semi-arid Israeli Negev.The most impacted shrub species is the Noaea mucronata(Forssk.)Asch.and Schweinf.In a four-year study,we found that herbaceous vegetation growth was greater in the dead shrub patches than in the surrounding inter-patch biocrusted spaces,suggesting that the dead shrub patches encompass improved micro-habitats.However,unexpectedly,the soil moisture in the dead shrub patches was consistently lower than that of the inter-patch biocrusted spaces.At the same time,soil quality in the dead shrub patches was higher than that in the inter-patch spaces.Therefore,it seems that the overall better soil conditions in the dead patches overcome the scarcity of soil-water,supporting increased herbaceous productivity.For explaining the discrepancy between herbaceous vegetation and soil-water,we formulated a conceptual framework,which highlights the key factors that regulate soil-water dynamics in this dryland ecosystem.We demonstrate that herbaceous vegetation is facilitated in the dead shrub patches by a legacy effect that takes place long after the shrubs have died.The dead shrub patches encompass a unique form of ecosystem engineering.The study highlights the complex and unpredicted impacts of prolonged droughts on dryland ecosystems.展开更多
基金supported by the Ministry of Science and Technologfunded by the Deshe Institute(Order Number 17-7480430).
文摘The loess plains cover approximately 2000.00 km2 of the northern Negev Desert,accounting for about 9%of Israel's total land area.As elsewhere,the loess in the Negev Desert is composed of wind-transported dust and sand particles that have been deposited in sink sites.The loess deposits are characteristically covered by biocrusts,which constitute a substantial share of the region's primary productivity.The biocrusts regulate the vascular vegetation communities,including herbaceous and woody plants,many of which are endemic and/or endangered plant species.Throughout history,the region's main land-uses have been based on extensive livestock grazing and runoff-harvesting agriculture,which both still exist to some extent.These land-uses did not challenge the sustainability of the geo-ecosystems over centuries and millennia.At present,predominant land-uses include intensive rangelands(1016.81 km2,encompassing 51%of the loess plains'area),croplands(encompassing both rainfed and irrigated cropping systems:930.92 km2,47%of the loess plains'area),and afforestation lands(158.75 km2).These current land-uses impose substantial challenges to the functioning of the loess plains.Further,urban and rural settlements have expanded considerably in the last decades(158.45 km2),accompanied by mass construction of infrastructures.Altogether,these new land-uses have caused widespread soil erosion,soil structure deformation,depletion of soil organic carbon,environmental contamination,native vegetation removal,invasion of plant species,and habitat fragmentation.Recent climate change has intensified these stressors,exacerbating adverse impacts and forming feedback loops that intensify land degradation and desertification.The declining ecosystem functioning over recent decades emphasizes the urgent need for passive and active restoration schemes.While some of these efforts have proven to be successful,other have failed.Therefore,proactive policy making and environmental legislation are needed to plan and develop schemes aimed at halting land degradation,while simultaneously maximizing nature conservation and restoration of degraded lands across the loess plains.Such actions are expected to increase the regions'capacity for climate change mitigation and adaptation.
文摘In drylands,biocrusts play crucial roles in regulating ecosystem functions.The study was conducted in the hilly rangelands of the semi-arid northern Negev of Israel,where we assessed the visual,morphological,spectral,and soil properties of livestock trampling routes and inter-route spaces in northern and southern facing hillslopes.Overall,both hillslope aspects were visually similar,whereas the ground surface of the routes was brighter(74.4%were characterized as having a'light'color)than the inter-route spaces(86.8%were characterized as having a'dark'color).These observations were supported by morphological identification of biocrust composition,which was dominated by cyanobacteria(67%)in the routes,and by mixed cyanobacteria/moss(56%)in the inter-routes.Mean Normalized Difference Vegetation Index(NDVI)was 24%higher in the inter-routes,while the mean Brightness Index(BI)was 12%higher in the routes.At the same time,the mean Crust Index(CI)was identical in the two microhabitats.Soil quality index(SQI),calculated based on the(pedoderm)soil properties of the two microhabitats,was 6%greater in the inter-routes than in the routes.This study suggests that recurrent trampling exacerbates soil compaction and shearing along the routes,thus preventing the successional development of complex biocrust compositions.
基金funded by the Nature and Parks Authority,and laboratory works was funded by the Israel Science Foundation(ISF)Grant No.602/21The Dead Sea and Arava Science Center is supported by the Ministry of Science and Technology。
文摘Land degradation affects extensive drylands around the world.Due to long-term misuse,the Israeli Sde Zin dryland site has faced severe degradation.The study objective was to assess the feasibility of passive restoration in recovering the site.The study was conducted in four land-units along a preservation-degradation continuum:(1)an area that has not faced anthropogenic disturbances(Ecological land);(2)an area that was proclaimed as a national park in the 1970s(Rehabilitation);(3)an area that was prone,until recently,to moderate anthropogenic pressures(Triangle);and(4)a dirt road that was subjected to long-term off-road traffic(Dirtroad).Soil was sampled and analyzed for its properties.The soil physical quality followed the trend of Ecological land>Rehabilitation>Triangle>Dirtroad.Specifically,high soil salinity in the latter three land-units is attributed to long-term erosional processes that exposed the underlying salic horizons.Herbaceous and shrubby vegetation cover was also monitored.The herbaceous vegetation cover followed the trend of Ecological land(86.4%)>Rehabilitation(40.3%)>Triangle(26.2%)>Dirtroad(2.1%),while the shrubby cover was 2.8%in the Ecological land-unit,and practically zero in the other land-units.It seems that despite the effectiveness of passive restoration in recovering the soil’s physical properties,the recovery of vegetation is limited by the severe soil salinity.
基金funded by the Israel Science Foundation(ISF),grant number 1260/15。
文摘A long-term drought has led to the mass mortality of shrubs in the semi-arid Israeli Negev.The most impacted shrub species is the Noaea mucronata(Forssk.)Asch.and Schweinf.In a four-year study,we found that herbaceous vegetation growth was greater in the dead shrub patches than in the surrounding inter-patch biocrusted spaces,suggesting that the dead shrub patches encompass improved micro-habitats.However,unexpectedly,the soil moisture in the dead shrub patches was consistently lower than that of the inter-patch biocrusted spaces.At the same time,soil quality in the dead shrub patches was higher than that in the inter-patch spaces.Therefore,it seems that the overall better soil conditions in the dead patches overcome the scarcity of soil-water,supporting increased herbaceous productivity.For explaining the discrepancy between herbaceous vegetation and soil-water,we formulated a conceptual framework,which highlights the key factors that regulate soil-water dynamics in this dryland ecosystem.We demonstrate that herbaceous vegetation is facilitated in the dead shrub patches by a legacy effect that takes place long after the shrubs have died.The dead shrub patches encompass a unique form of ecosystem engineering.The study highlights the complex and unpredicted impacts of prolonged droughts on dryland ecosystems.
