Preserving Tibet’s unique history and cultural heritage relies on the sustainability of the Tibetan croplands,which are characterized by highland barley,the only cereal crop cultivated over 4000 m above sea level.Yet...Preserving Tibet’s unique history and cultural heritage relies on the sustainability of the Tibetan croplands,which are characterized by highland barley,the only cereal crop cultivated over 4000 m above sea level.Yet it is unknown how these croplands will respond to climate change.Here,using yield statistics from 1985 to 2015,we found that the impact of temperature anomalies on the Tibetan crop yield shifted from nonsignificant(P>0.10)in the 1980s and 1990s to significantly negative(P<0.05)in recent years.Meanwhile,the apparent sensitivity of the crop yield to temperature anomalies almost doubled,from(–0.13±0.20)to(–0.22±0.14)t·ha^(-1)℃^(–1).The emerging negative impacts of higher temperatures suggest an increasing vulnerability of Tibetan croplands to warmer climate.With global warming scenarios of+1.5 or+2.0℃above the pre-industry level,the temperature sensitivities of crop yield may further increase to(–0.33±0.10)and(–0.51±0.18)t·ha^(-1)℃^(–1),respectively,making the crops 2–3 times more vulnerable to warmer temperatures than they are today.展开更多
Warming and grazing,and ltter quality jointly determine liter decomposition and nutrient releases in grazing ecosystems.However,their effects have previously been studied in isolation.We conducted a two factorial expe...Warming and grazing,and ltter quality jointly determine liter decomposition and nutrient releases in grazing ecosystems.However,their effects have previously been studied in isolation.We conducted a two factorial experiment with asymmetric warming using infrared heaters and moderate grazing in an alpine meadow.Litter samples were collected from all plots in each treatment,among which some subsamples were placed in their original plots and other samples were translocated to other treatment plots to test the relative effects of each treatment on litter decomposition and nutrient releases.We found that warming rather than grazing alone significantly increased total losses of litter mass,total organic carbon,total nitrogen(TN)and total phosphorus(TP)per unit area due to increases in both mass loss rates and ltter biomass.However,grazing with warming did not affect their total mass losses because increased mass loss was offset by decreased litter biomass compared with the control.Seasonal mean soil temperature better predicted litter decomposition than litter lignin content or carbon to nitrogen ratio.There were interactions between warming and grazing,but there were no interactions between them and litter quality on litter decomposition.The temperature sensitivity of TN loss was higher than that of TP loss per unit area.Our results suggest that increased temperature has a greater effect on litter decomposition and nutrient release than change in litter quality,and that more N release from litter could result in greater P deficiency in the alpine meadow.展开更多
Fine-root decomposition is a critical process regulating ecosystem carbon cycles and affecting nutrient cycling and soil fertility.However,whether interaction between warming and grazing affects fine-root decompositio...Fine-root decomposition is a critical process regulating ecosystem carbon cycles and affecting nutrient cycling and soil fertility.However,whether interaction between warming and grazing affects fine-root decomposition is still under-researched in natural grasslands.A two-factorial experiment with asymmetric warming(i.e.daytime vs.nighttime and growing season vs.nongrowing season)and moderate grazing(i.e.about average 50%forage utilization rate)was conducted to explore whether warming and grazing affect fine-root decomposition and loss of nutrients during a 2-year decomposition period in an alpine meadow on the Tibetan Plateau.Both warming and grazing facilitated carbon cycling through increase in fine-root decomposition,and influenced element cycling which varies among elements.The effects of warming and grazing on fine-root decomposition and loss of nutrients were additive.Both warming and grazing significantly increased cumulative percentage mass loss and total organic carbon loss of fine roots during the 2-year experiment.Only warming with grazing treatment reduced percentage nitrogen loss,whereas warming,regardless of grazing,decreased percentage phosphorus loss.Warming and grazing alone increased percentage loss of potassium,sodium,calcium and magnesium compared with control.There were no interactions between warming and grazing on fine-root decomposition and loss of nutrients.There was greater temperature sensitivity of decreased phosphorus loss than that of decreased nitrogen loss.Different temperature sensitivities of percentage loss of nutrients from fine-root decomposition would alter ratios of the available nutrients in soils,and may further affect ecosystem structure and functions in future warming.展开更多
基金the Second Tibetan Plateau Scien-tific Expedition and Research Program(2019QZKK0405)the National Natural Science Foundation of China project Basic Science Center for Tibetan Plateau Earth System(41988101).
文摘Preserving Tibet’s unique history and cultural heritage relies on the sustainability of the Tibetan croplands,which are characterized by highland barley,the only cereal crop cultivated over 4000 m above sea level.Yet it is unknown how these croplands will respond to climate change.Here,using yield statistics from 1985 to 2015,we found that the impact of temperature anomalies on the Tibetan crop yield shifted from nonsignificant(P>0.10)in the 1980s and 1990s to significantly negative(P<0.05)in recent years.Meanwhile,the apparent sensitivity of the crop yield to temperature anomalies almost doubled,from(–0.13±0.20)to(–0.22±0.14)t·ha^(-1)℃^(–1).The emerging negative impacts of higher temperatures suggest an increasing vulnerability of Tibetan croplands to warmer climate.With global warming scenarios of+1.5 or+2.0℃above the pre-industry level,the temperature sensitivities of crop yield may further increase to(–0.33±0.10)and(–0.51±0.18)t·ha^(-1)℃^(–1),respectively,making the crops 2–3 times more vulnerable to warmer temperatures than they are today.
基金supported by grants from the National Natural Science Foundation of China(41731175 and 41988101)the Strategic Priority Research Program A of the Chinese Academy of Sciences(XDA20050101)+1 种基金the Joint Key Research Fund under a cooperative agreement between the National Natural Science Foundation of China(NSFC)and Tibet Autonomous Region(TAR)(U20A2005)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0608 and 2019QZKK0302).
基金the Joint Key Research Fund under a cooperative agreement between the National Natural Science Foundation of China(NSFC)and Tibet Autonomous Region(TAR)(U20A2005)the National Natural Science Foundation of China(41731175,31872994_and 31770524)+1 种基金the Strategic Priority Research Program A of theChineseAcademyof Sciences(XDA20050101)the Second Tibetan Plateau Scientific Expedition and Research(STEP) program(2019QZKK0608 and 2019QZKK0302)。
文摘Warming and grazing,and ltter quality jointly determine liter decomposition and nutrient releases in grazing ecosystems.However,their effects have previously been studied in isolation.We conducted a two factorial experiment with asymmetric warming using infrared heaters and moderate grazing in an alpine meadow.Litter samples were collected from all plots in each treatment,among which some subsamples were placed in their original plots and other samples were translocated to other treatment plots to test the relative effects of each treatment on litter decomposition and nutrient releases.We found that warming rather than grazing alone significantly increased total losses of litter mass,total organic carbon,total nitrogen(TN)and total phosphorus(TP)per unit area due to increases in both mass loss rates and ltter biomass.However,grazing with warming did not affect their total mass losses because increased mass loss was offset by decreased litter biomass compared with the control.Seasonal mean soil temperature better predicted litter decomposition than litter lignin content or carbon to nitrogen ratio.There were interactions between warming and grazing,but there were no interactions between them and litter quality on litter decomposition.The temperature sensitivity of TN loss was higher than that of TP loss per unit area.Our results suggest that increased temperature has a greater effect on litter decomposition and nutrient release than change in litter quality,and that more N release from litter could result in greater P deficiency in the alpine meadow.
基金This research was supported by grants from the National Natural Science Foundation of China(41731175,31770524 and 31872994)the Strategic Priority Research Program A of the Chinese Academy of Sciences(XDA20050101)+1 种基金the Joint Key Research Fund(U20A2005)under cooperative agreement between the National Natural Science Foundation of China(NSFC)and Tibet Autonomous Region(TAR)he Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0302 and 2019QZKK0608).
文摘Fine-root decomposition is a critical process regulating ecosystem carbon cycles and affecting nutrient cycling and soil fertility.However,whether interaction between warming and grazing affects fine-root decomposition is still under-researched in natural grasslands.A two-factorial experiment with asymmetric warming(i.e.daytime vs.nighttime and growing season vs.nongrowing season)and moderate grazing(i.e.about average 50%forage utilization rate)was conducted to explore whether warming and grazing affect fine-root decomposition and loss of nutrients during a 2-year decomposition period in an alpine meadow on the Tibetan Plateau.Both warming and grazing facilitated carbon cycling through increase in fine-root decomposition,and influenced element cycling which varies among elements.The effects of warming and grazing on fine-root decomposition and loss of nutrients were additive.Both warming and grazing significantly increased cumulative percentage mass loss and total organic carbon loss of fine roots during the 2-year experiment.Only warming with grazing treatment reduced percentage nitrogen loss,whereas warming,regardless of grazing,decreased percentage phosphorus loss.Warming and grazing alone increased percentage loss of potassium,sodium,calcium and magnesium compared with control.There were no interactions between warming and grazing on fine-root decomposition and loss of nutrients.There was greater temperature sensitivity of decreased phosphorus loss than that of decreased nitrogen loss.Different temperature sensitivities of percentage loss of nutrients from fine-root decomposition would alter ratios of the available nutrients in soils,and may further affect ecosystem structure and functions in future warming.
