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
INTRODUCTION.Dung middens(also dung hills,dung latrines,stud piles,or fecal piles)are spatially fixed points where animals regularly deposit urine and feces.Most of the animals that are known to construct dung middens...INTRODUCTION.Dung middens(also dung hills,dung latrines,stud piles,or fecal piles)are spatially fixed points where animals regularly deposit urine and feces.Most of the animals that are known to construct dung middens are odd-and even-toed ungulates(Walther et al.1983).They range in size from the Kirk’s dik-dik,Madoqua kirkii(Ono et al.1988),to the white rhinoceros,Ceratotherium simum(Marneweck et al.2018).Yet,this behavior has also been observed in carnivores(Darden et al.2008;Rodgers et al.2015),as well as primates(Eppley et al.2016).In antelopes,middens are constructed mostly by males(in dik-dik and klipspringer,Oreotragus oreotragus,both sexes deposit in the midden,Macdonald 1984).A communal form of social depositing was found in several species;for example,in the European badger,Meles meles,and the whitefooted sportive lemur,Lepilemur leucopus(Charpentier et al.2008).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
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.
文摘INTRODUCTION.Dung middens(also dung hills,dung latrines,stud piles,or fecal piles)are spatially fixed points where animals regularly deposit urine and feces.Most of the animals that are known to construct dung middens are odd-and even-toed ungulates(Walther et al.1983).They range in size from the Kirk’s dik-dik,Madoqua kirkii(Ono et al.1988),to the white rhinoceros,Ceratotherium simum(Marneweck et al.2018).Yet,this behavior has also been observed in carnivores(Darden et al.2008;Rodgers et al.2015),as well as primates(Eppley et al.2016).In antelopes,middens are constructed mostly by males(in dik-dik and klipspringer,Oreotragus oreotragus,both sexes deposit in the midden,Macdonald 1984).A communal form of social depositing was found in several species;for example,in the European badger,Meles meles,and the whitefooted sportive lemur,Lepilemur leucopus(Charpentier et al.2008).
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.
