Agriophyllum squarrosum is an annual desert plant widely distributed on mobile and semi-mobile dunes in all the sandy deserts of China. We studied the growth and physiological properties of A. squarrosum seedlings und...Agriophyllum squarrosum is an annual desert plant widely distributed on mobile and semi-mobile dunes in all the sandy deserts of China. We studied the growth and physiological properties of A. squarrosum seedlings under different sand burial depths in 2010 and 2011 at Horqin Sandy Land, Inner Mongolia to understand the ability and mechanism that A. squarrosum withstands sand burial. The results showed that A. squarrosum had a strong ability to withstand sand burial. Its survival rate, plant height and biomass increased significantly at a burial depth 25% of seedling height and decreased significantly only when the burial depth exceeded the height of the seedlings; some plants still survived even if the burial depth reached 266% of a seedling height. The malondialdehyde (MDA) content and membrane permeability of the plant did not change significantly as long as the burial depth was not greater than the seedling height; lipid peroxidation increased and cell membranes were damaged if the burial depth was increased further. When subjected to sand burial stress, superoxide dismutase (SOD) and peroxidase (POD) activities and free proline content increased in the seedlings, while the catalase (CAT) activity and soluble sugar content decreased. Sand burial did not lead to water stress. Reductions in photosynthetic area and cell membrane damage caused by sand burial may be the major mechanisms increasing mortality and inhibiting growth of the seedling. But the increases in SOD and POD activities and proline content must play a certain role in reducing sand burial damage.展开更多
Burial of different growth stages of plants (e.g., adult plants, seedlings and seeds) is frequent in dune ecosystems. The soil micro-environment, which differs from surface conditions, influences the survival and gr...Burial of different growth stages of plants (e.g., adult plants, seedlings and seeds) is frequent in dune ecosystems. The soil micro-environment, which differs from surface conditions, influences the survival and growth of dune plants. To sum up knowledge about the survival mechanisms of plants under sand burial and to promote practical rehabilitation of dune vegetation, we reviewed relevant published literature and concluded that: (1) Focus in recent years has been on impacts of sand burial on seed germination and seedling emergence. Generally, shallow burial increased seed germination and seedling emergence, but deeper burial was negative. Buried at the same depth, large seeds showed higher germination and seedling emergence rates, attributed to larger energy reserves. (2) Survival, growth and reproduction rates of dune plants show plasticity in response to sand burial. Long-term deep burial is fatal because it creates a physical barrier which overcomes the vertical growth of plants, reduces photosynthetic leaf area, and limits oxygen availability to roots. Modest burial, on the other hand, is advantageous for growth and reproduction of many dune plants, due to protection from excessive temperature and drought. (3) There are few reports concerning effects of sand burial on plant physiology, but a limited number of studies indicate that partial burial increases water use efficiency, chlorophyll content, transpiration rate and net photosynthetic rates. The antioxidant protective enzyme system and osmolyte balance were reported to be involved in the mechanisms of dune plant resistance to burial.展开更多
To understand the effects of grazing activities and climate change on sandy grassland ecosystems in northem China, a livestock field grazing and enclosure experiment was conducted from 1992 to 2006 in Horqin Sand Land...To understand the effects of grazing activities and climate change on sandy grassland ecosystems in northem China, a livestock field grazing and enclosure experiment was conducted from 1992 to 2006 in Horqin Sand Land, Inner Mongolia. The results showed that sustained heavy grazing resulted in serious degradation of the vegetation; moderate grazing can maintain vegetation stabilization; and light grazing can promote rapid restoration of degraded vegetation. The livestock productivity was the highest in the moderate grazing grassland, and sustained heavy grazing resulted in rapid decrease of the livestock productivity. Heavy grazing can cause a retrogressive succession of grassland vegetation, whereas moderate and light grazing may promote progressive succession of plant species. The effects of changing climate on succession processes were not significant in the short term; a warm-humid climate is favorable to restoration of degraded vegetation, whereas a sustained warm-drought climate may result in degradation of grassland vegetation. Heavy livestock grazing should be stopped for the sustainable use of grassland; the proper grazing intensity for sandy grassland is two to three sheep or sheep equivalents per hectare in Inner Mongolia.展开更多
Growth and physiological responses of wheat to sand burial were studied in Horqin Sandy Land, to determine the impact on productivity and survival as well as antioxidant enzymes responses. This study consisted of one ...Growth and physiological responses of wheat to sand burial were studied in Horqin Sandy Land, to determine the impact on productivity and survival as well as antioxidant enzymes responses. This study consisted of one control (no sand) and four sand burial treatments: 25%, 50%, 75% and 100% of seedling height, respectively. Minor burial (25%) had no effect on wheat growth and survival; deep burial (100%) was fatal, and the others had an intermediate effect. Thus, the survival limit to sand burial was equal to seedling height. Sand burial mainly decreased shoot biomass and crop yield, but had small effects on belowground biomass. Superoxide dismutase (SOD) activity increased with time after burial in all treatments with surviving plants. Peroxidase (POD) activity increased after six days under burial, and catalase (CAT) activity de- creased after burial, but recovered after 12 days. The concentration of malondialdehyde (MDA), a marker for oxidative stress, was low on the sixth day, but increased thereafter with burial depth. Thus, sand burial 〉25% should be avoided due to growth rate reduction leading to reduced crop yield, and even 25% burial showed physiological indicators of stress.展开更多
There is a great deal of literature on the effects of sand burial upon the survival and growth of desert plants, but the physiological adaption mechanisms of desert plants to sand burial have as yet rarely been studie...There is a great deal of literature on the effects of sand burial upon the survival and growth of desert plants, but the physiological adaption mechanisms of desert plants to sand burial have as yet rarely been studied. Artemisia halodendron is widely distributed in the semi-arid deserts of China and is a dominant species in semi-moving dune vegetation. The growth and physiological properties ofA. halodendron seedlings under different sand burial depths were studied in 2010 and 2011 in the Horqin Sand Land, Inner Mongolia, to better understand the ability and physiological mechanism by which desert plants withstand sand burial. The results showed that A. halodendron as a prammophyte species had a stronger ability to withstand sand burial compared to non-prammophytes, with some plants still surviving even if buried to a depth reaching 225% of seedling height. Although seedling growth was inhibited significantly once the depth of sand burial reached 50% of the seedling height, seedling survival did not decrease significantly until the burial depth exceeded 100% of the seedling height. Sand burial did not result in significant water stress or MDA (Malondialdehyde) accumulation in the seedlings, but membrane permeability increased significantly when the burial depth exceeded 100% of the seedling height. After being subjected to sand burial stress, POD (Peroxidase) activity and proline content increased significantly, but SOD (Superoxide Dismutase) and POD activities and soluble sugar content did not. The primary mechanism resulting in in- creased mortality and growth inhibition were that cell membranes were damaged and photosynthetic area decreased when subjected to the severe stress of sand burial, while proline and POD played key roles in osmotic adjustment and protecting cell membranes from damage, respectively.展开更多
The Pearl River Delta(PRD)region on the southeast coast of China has long been known as a highly productive fishing ground.Since the late 1980s,fishing pressure in the PRD has been intense,which warrants concerns of p...The Pearl River Delta(PRD)region on the southeast coast of China has long been known as a highly productive fishing ground.Since the late 1980s,fishing pressure in the PRD has been intense,which warrants concerns of potential fishery-related impacts on the food resources and foraging ecology of apex marine predators in this region,such as the Indo-Pacific humpback dolphin(Sousa chinensis).In this study,we examined 54 stomachs with food remains,collected from beached carcasses of humpback dolphins recovered during fifteen years between 2003 and 2017.The 6043 identified prey items represent 62 teleost taxa,primarily small estuarine fish,but also larger reef fish.The dolphins appear to be opportunistic foragers,hunting across the water-column,with preference for shoaling and meaty fishes(e.g.Collichthys lucidus IRI%=38.6%,Johnius belangerii IRI%=23.1%,Mugil cephalus IRI%=14.0%).Our findings suggest a dietary shift in recent years,from primarily demersal(as previously reported)to greater intake of neritic and pelagic fish.Dolphin foraging group size has decreased in recent years,which corresponds with declining size and numbers of prey items retrieved from dolphin stomachs.We suggest that these are indicators of declining food resources.Faced with a shortage of preferred prey,humpback dolphins may have broadened their dietary spectrum to maintain their daily energy intake,while their foraging group size decreased in response to the altered tradeoff between the costs and benefits of group foraging.展开更多
基金funded by the National Natural Science Foundation of China (31270752, 30972422)the National Key Technology R&D Program (2011BAC07B02-06)the Foundation for Excellent Youth Scholars of CAREERI, Chinese Academy of Sciences (Y451081001, Y451111001)
文摘Agriophyllum squarrosum is an annual desert plant widely distributed on mobile and semi-mobile dunes in all the sandy deserts of China. We studied the growth and physiological properties of A. squarrosum seedlings under different sand burial depths in 2010 and 2011 at Horqin Sandy Land, Inner Mongolia to understand the ability and mechanism that A. squarrosum withstands sand burial. The results showed that A. squarrosum had a strong ability to withstand sand burial. Its survival rate, plant height and biomass increased significantly at a burial depth 25% of seedling height and decreased significantly only when the burial depth exceeded the height of the seedlings; some plants still survived even if the burial depth reached 266% of a seedling height. The malondialdehyde (MDA) content and membrane permeability of the plant did not change significantly as long as the burial depth was not greater than the seedling height; lipid peroxidation increased and cell membranes were damaged if the burial depth was increased further. When subjected to sand burial stress, superoxide dismutase (SOD) and peroxidase (POD) activities and free proline content increased in the seedlings, while the catalase (CAT) activity and soluble sugar content decreased. Sand burial did not lead to water stress. Reductions in photosynthetic area and cell membrane damage caused by sand burial may be the major mechanisms increasing mortality and inhibiting growth of the seedling. But the increases in SOD and POD activities and proline content must play a certain role in reducing sand burial damage.
基金funded by Foundation for Excellent Youth Scholars of CAREERI, CAS (Y451081001)Chinese National Support Projects of Science and Technology (2011BAC07B02)funded by the Chinese Academy of Sciences "Professorship for Senior International Scientists" (Grant No. Y229D91001)
文摘Burial of different growth stages of plants (e.g., adult plants, seedlings and seeds) is frequent in dune ecosystems. The soil micro-environment, which differs from surface conditions, influences the survival and growth of dune plants. To sum up knowledge about the survival mechanisms of plants under sand burial and to promote practical rehabilitation of dune vegetation, we reviewed relevant published literature and concluded that: (1) Focus in recent years has been on impacts of sand burial on seed germination and seedling emergence. Generally, shallow burial increased seed germination and seedling emergence, but deeper burial was negative. Buried at the same depth, large seeds showed higher germination and seedling emergence rates, attributed to larger energy reserves. (2) Survival, growth and reproduction rates of dune plants show plasticity in response to sand burial. Long-term deep burial is fatal because it creates a physical barrier which overcomes the vertical growth of plants, reduces photosynthetic leaf area, and limits oxygen availability to roots. Modest burial, on the other hand, is advantageous for growth and reproduction of many dune plants, due to protection from excessive temperature and drought. (3) There are few reports concerning effects of sand burial on plant physiology, but a limited number of studies indicate that partial burial increases water use efficiency, chlorophyll content, transpiration rate and net photosynthetic rates. The antioxidant protective enzyme system and osmolyte balance were reported to be involved in the mechanisms of dune plant resistance to burial.
基金funded by a Chinese National Key Project for Basic Scientific Research (2009CB421303)a Chinese National Fund Project (30972422)
文摘To understand the effects of grazing activities and climate change on sandy grassland ecosystems in northem China, a livestock field grazing and enclosure experiment was conducted from 1992 to 2006 in Horqin Sand Land, Inner Mongolia. The results showed that sustained heavy grazing resulted in serious degradation of the vegetation; moderate grazing can maintain vegetation stabilization; and light grazing can promote rapid restoration of degraded vegetation. The livestock productivity was the highest in the moderate grazing grassland, and sustained heavy grazing resulted in rapid decrease of the livestock productivity. Heavy grazing can cause a retrogressive succession of grassland vegetation, whereas moderate and light grazing may promote progressive succession of plant species. The effects of changing climate on succession processes were not significant in the short term; a warm-humid climate is favorable to restoration of degraded vegetation, whereas a sustained warm-drought climate may result in degradation of grassland vegetation. Heavy livestock grazing should be stopped for the sustainable use of grassland; the proper grazing intensity for sandy grassland is two to three sheep or sheep equivalents per hectare in Inner Mongolia.
基金funded by Foundation for Excellent Youth Scholars of CAREERI,CAS (Y451081001)National Natural Science Foundation of China (41401620,41201249)The Chinese Academy of Sciences has kindly granted Prof.O. Andrén a 'Professorship for Senior International Scientists' (Grant No.Y229D91001)
文摘Growth and physiological responses of wheat to sand burial were studied in Horqin Sandy Land, to determine the impact on productivity and survival as well as antioxidant enzymes responses. This study consisted of one control (no sand) and four sand burial treatments: 25%, 50%, 75% and 100% of seedling height, respectively. Minor burial (25%) had no effect on wheat growth and survival; deep burial (100%) was fatal, and the others had an intermediate effect. Thus, the survival limit to sand burial was equal to seedling height. Sand burial mainly decreased shoot biomass and crop yield, but had small effects on belowground biomass. Superoxide dismutase (SOD) activity increased with time after burial in all treatments with surviving plants. Peroxidase (POD) activity increased after six days under burial, and catalase (CAT) activity de- creased after burial, but recovered after 12 days. The concentration of malondialdehyde (MDA), a marker for oxidative stress, was low on the sixth day, but increased thereafter with burial depth. Thus, sand burial 〉25% should be avoided due to growth rate reduction leading to reduced crop yield, and even 25% burial showed physiological indicators of stress.
基金funded by the Chinese National Fund Projects (Nos.31270752 and 30972422)by a Chinese National Support Project of Science and Technology (No.2011BAC07B02-06)
文摘There is a great deal of literature on the effects of sand burial upon the survival and growth of desert plants, but the physiological adaption mechanisms of desert plants to sand burial have as yet rarely been studied. Artemisia halodendron is widely distributed in the semi-arid deserts of China and is a dominant species in semi-moving dune vegetation. The growth and physiological properties ofA. halodendron seedlings under different sand burial depths were studied in 2010 and 2011 in the Horqin Sand Land, Inner Mongolia, to better understand the ability and physiological mechanism by which desert plants withstand sand burial. The results showed that A. halodendron as a prammophyte species had a stronger ability to withstand sand burial compared to non-prammophytes, with some plants still surviving even if buried to a depth reaching 225% of seedling height. Although seedling growth was inhibited significantly once the depth of sand burial reached 50% of the seedling height, seedling survival did not decrease significantly until the burial depth exceeded 100% of the seedling height. Sand burial did not result in significant water stress or MDA (Malondialdehyde) accumulation in the seedlings, but membrane permeability increased significantly when the burial depth exceeded 100% of the seedling height. After being subjected to sand burial stress, POD (Peroxidase) activity and proline content increased significantly, but SOD (Superoxide Dismutase) and POD activities and soluble sugar content did not. The primary mechanism resulting in in- creased mortality and growth inhibition were that cell membranes were damaged and photosynthetic area decreased when subjected to the severe stress of sand burial, while proline and POD played key roles in osmotic adjustment and protecting cell membranes from damage, respectively.
基金supported by the National Basic Research Program of China (2009CB421303)the Knowledge Innovation Programs of the Chinese Academy of Sciences (KZCX2-YW-431)+1 种基金the National Nature Science Foundation of China (40601008)National Key Technologies Support Program of China (2006BAC01A12, 2006BAD26B02)
基金This study was funded by the National Natural Science Foundation of China(41576128)the Natural Science Foundation of Guangdong Province(2017A030308005)in China+3 种基金the Ocean Park Conservation Foundation Hong Kong(MM01.1920)Alashan Society of Entrepreneurs and Ecology(SEE)the General Research Fund of the Research Grants Council(RGC)of Hong Kong(HKU_17100015 to LK and CityU_160613 to TCW)Field-based observations were facilitated by ongoing photo-ID study supported primarily with LK’s Marine Ecology Enhancement Fund grants MEEF2017015,MEEF2017015A and MEEF2017015B.
文摘The Pearl River Delta(PRD)region on the southeast coast of China has long been known as a highly productive fishing ground.Since the late 1980s,fishing pressure in the PRD has been intense,which warrants concerns of potential fishery-related impacts on the food resources and foraging ecology of apex marine predators in this region,such as the Indo-Pacific humpback dolphin(Sousa chinensis).In this study,we examined 54 stomachs with food remains,collected from beached carcasses of humpback dolphins recovered during fifteen years between 2003 and 2017.The 6043 identified prey items represent 62 teleost taxa,primarily small estuarine fish,but also larger reef fish.The dolphins appear to be opportunistic foragers,hunting across the water-column,with preference for shoaling and meaty fishes(e.g.Collichthys lucidus IRI%=38.6%,Johnius belangerii IRI%=23.1%,Mugil cephalus IRI%=14.0%).Our findings suggest a dietary shift in recent years,from primarily demersal(as previously reported)to greater intake of neritic and pelagic fish.Dolphin foraging group size has decreased in recent years,which corresponds with declining size and numbers of prey items retrieved from dolphin stomachs.We suggest that these are indicators of declining food resources.Faced with a shortage of preferred prey,humpback dolphins may have broadened their dietary spectrum to maintain their daily energy intake,while their foraging group size decreased in response to the altered tradeoff between the costs and benefits of group foraging.