Ecosystem of eastern Eurasian steppe is facing more and more challenges of global issues such as climate change, food and ecological security and human excessive utilization since the 21st century. Facing on the incre...Ecosystem of eastern Eurasian steppe is facing more and more challenges of global issues such as climate change, food and ecological security and human excessive utilization since the 21st century. Facing on the increasingly prominent international issues, it is very essential for relevant countries, international organizations and domestic counterparts to enhance systematic and mutual cooperation and exchanges to carry out scientific research and develop protection practice on the Eurasian steppe.展开更多
Shrub species are used in restoration projects on dryland for their facilitation effects,which include environmental improvements and protection from herbivore feeding.Facilitation effects on forage grasses are potent...Shrub species are used in restoration projects on dryland for their facilitation effects,which include environmental improvements and protection from herbivore feeding.Facilitation effects on forage grasses are potentially important in improving grazing capacity on rangelands.However,the morphology-dependent performance of benefactor plants in facilitating forage species growth and supplementation under moderate grazing intensity remains unclear.Here,our main purpose was to measure facilitation performance in terms of the survival of a native forage grass,Agropyron cristatum(L.)Gaertn.(Gramineae).,in accordance with the growth conditions of a sand-fixing benefactor shrub,Caragana microphylla Lam.,in the Hulun Buir Grassland,northern China.Six study sites with patches of A.cristatum and C.microphylla were established at the foot of fixed sand dunes.At each site,five quadrats were set in places where C.microphylla coverage was 100%and A.cristatum grew among the shrubs(shrub quadrats),and another five were set where A.cristatum grew alone without C.microphylla(grass quadrats).We measured the morphological traits of C.microphylla and A.cristatum in all 60 quadrats,along with the soil water content and soil temperature.The data were compared between the shrub and grass quadrats by generalized linear mixed-effect models to assess the shrub's facilitation effects.We also used such models to elucidate the relationship between the average height of C.microphylla and the morphological traits of A.cristatum in the shrub quadrats.The maximum height,average grazed height,and the number of seed heads of A.cristatum were greater in the shrub quadrats than in the grass quadrats.The soil surface temperature was lower in the shrub quadrats.The maximum height and seed head number of A.cristatum were positively associated with the average height of C.microphylla.These results suggest that the grazing impact and heat stress were smaller in shrub quadrats than in grass quadrats,and that the degree of this protective effect depended on the shrub height.The shrub canopy seemed to reduce the increase in soil temperature and keep the grass vigorous.Livestock likely avoided grazing grasses in the C.microphylla patches because of the shrub's spiny leaves;only the upper parts of the grass stems(including the seed heads)protruding from the shrub canopy were grazed.The sand-fixing shrub thus moderates the grazing impact and soil temperature,and contributes to vegetation restoration and grazing system sustainability.展开更多
Rodents play an important role in rangelands through the engineering of extensive burrow systems,which provides key habitats for many animal and plant species.We have analyzed the long-term variation in the abun...Rodents play an important role in rangelands through the engineering of extensive burrow systems,which provides key habitats for many animal and plant species.We have analyzed the long-term variation in the abundance and distribution of rodent burrows in grazing ecosystems of southern Russia(Kalmykia)under the landscape change from desert to steppe caused by the drastic reduction of livestock after the collapse of the USSR in the early 1990s.We conducted burrow surveys in the“desert”(1980)and“steppe”(2017)periods on 193-km transects.We found considerable changes in burrow abundance and distribution,as well as evidence of desert habitat fragmentation and isolation caused by the expansion of tall-grass communities.Burrows of the open-dwelling diurnal ground squirrel(Spermophilus pygmaeus),the dominant and the keystone species during the“desert”period,almost completely disappeared from the rodent burrow network by 2017,indicating significant habitat loss.In contrast,the burrows of the folivorous social vole(Microtus socialis)which was rare in the 1980s,became abundant and ubiquitously distributed.The burrow density of the desert-dwelling psammophilous midday gerbil(Meriones meridianus)decreased,while the distances between occupied patches increased,indicating desert habitat fragmentation and loss of population connectivity.Burrows of the folivorous tamarisk gerbils(M.tamariscinus)were recorded only sporadically in both 1980 and 2017.The observed changes in the rodent burrow network,the key component of grazing ecosystems,correlate with rodent species ecology and can have long-term and important consequences for ecosystem functioning.展开更多
文摘Ecosystem of eastern Eurasian steppe is facing more and more challenges of global issues such as climate change, food and ecological security and human excessive utilization since the 21st century. Facing on the increasingly prominent international issues, it is very essential for relevant countries, international organizations and domestic counterparts to enhance systematic and mutual cooperation and exchanges to carry out scientific research and develop protection practice on the Eurasian steppe.
基金supported by the Tripartite Environment Ministers Meeting(TEMM)JSPS KAKENHI(JP19H04316).We thank the staff of the Chinese Research Academy of Environmental Sciences(CRAES)the Overseas Environmental Cooperation Center(OECC),Japan for their support during the field survey.
文摘Shrub species are used in restoration projects on dryland for their facilitation effects,which include environmental improvements and protection from herbivore feeding.Facilitation effects on forage grasses are potentially important in improving grazing capacity on rangelands.However,the morphology-dependent performance of benefactor plants in facilitating forage species growth and supplementation under moderate grazing intensity remains unclear.Here,our main purpose was to measure facilitation performance in terms of the survival of a native forage grass,Agropyron cristatum(L.)Gaertn.(Gramineae).,in accordance with the growth conditions of a sand-fixing benefactor shrub,Caragana microphylla Lam.,in the Hulun Buir Grassland,northern China.Six study sites with patches of A.cristatum and C.microphylla were established at the foot of fixed sand dunes.At each site,five quadrats were set in places where C.microphylla coverage was 100%and A.cristatum grew among the shrubs(shrub quadrats),and another five were set where A.cristatum grew alone without C.microphylla(grass quadrats).We measured the morphological traits of C.microphylla and A.cristatum in all 60 quadrats,along with the soil water content and soil temperature.The data were compared between the shrub and grass quadrats by generalized linear mixed-effect models to assess the shrub's facilitation effects.We also used such models to elucidate the relationship between the average height of C.microphylla and the morphological traits of A.cristatum in the shrub quadrats.The maximum height,average grazed height,and the number of seed heads of A.cristatum were greater in the shrub quadrats than in the grass quadrats.The soil surface temperature was lower in the shrub quadrats.The maximum height and seed head number of A.cristatum were positively associated with the average height of C.microphylla.These results suggest that the grazing impact and heat stress were smaller in shrub quadrats than in grass quadrats,and that the degree of this protective effect depended on the shrub height.The shrub canopy seemed to reduce the increase in soil temperature and keep the grass vigorous.Livestock likely avoided grazing grasses in the C.microphylla patches because of the shrub's spiny leaves;only the upper parts of the grass stems(including the seed heads)protruding from the shrub canopy were grazed.The sand-fixing shrub thus moderates the grazing impact and soil temperature,and contributes to vegetation restoration and grazing system sustainability.
基金the Russian Foundation for Basic Research(grants 16-04-00739 for AT and 18-34-00155 for ES).
文摘Rodents play an important role in rangelands through the engineering of extensive burrow systems,which provides key habitats for many animal and plant species.We have analyzed the long-term variation in the abundance and distribution of rodent burrows in grazing ecosystems of southern Russia(Kalmykia)under the landscape change from desert to steppe caused by the drastic reduction of livestock after the collapse of the USSR in the early 1990s.We conducted burrow surveys in the“desert”(1980)and“steppe”(2017)periods on 193-km transects.We found considerable changes in burrow abundance and distribution,as well as evidence of desert habitat fragmentation and isolation caused by the expansion of tall-grass communities.Burrows of the open-dwelling diurnal ground squirrel(Spermophilus pygmaeus),the dominant and the keystone species during the“desert”period,almost completely disappeared from the rodent burrow network by 2017,indicating significant habitat loss.In contrast,the burrows of the folivorous social vole(Microtus socialis)which was rare in the 1980s,became abundant and ubiquitously distributed.The burrow density of the desert-dwelling psammophilous midday gerbil(Meriones meridianus)decreased,while the distances between occupied patches increased,indicating desert habitat fragmentation and loss of population connectivity.Burrows of the folivorous tamarisk gerbils(M.tamariscinus)were recorded only sporadically in both 1980 and 2017.The observed changes in the rodent burrow network,the key component of grazing ecosystems,correlate with rodent species ecology and can have long-term and important consequences for ecosystem functioning.