Aims We aim to construct a comprehensive global database of litter decomposition rate(k value)estimated by surface floor litterbags,and investigate the direct and indirect effects of impact factors such as geographic ...Aims We aim to construct a comprehensive global database of litter decomposition rate(k value)estimated by surface floor litterbags,and investigate the direct and indirect effects of impact factors such as geographic factors(latitude and altitude),climatic factors(mean annual tempePlrature,MAT;mean annual precipitation,MAP)and litter quality factors(the contents of N,P,K,Ca,Mg and C:N ratio,lignin:N ratio)on litter decomposition.Methods We compiled a large data set of litter decomposition rates(k values)from 110 research sites and conducted simple,multiple regression and path analyses to explore the relationship between the k values and impact factors at the global scale.Important findings The k values tended to decrease with latitude(LAT)and lignin content(LIGN)of litter but increased with temperature,precipitation and nutrient concentrations at the large spatial scale.Single factor such as climate,litter quality and geographic variable could not explain litter decomposition rates well.However,the combination of total nutrient(TN)elements and C:N accounted for 70.2%of the variation in the litter decomposition rates.The combination of LAT,MAT,C:N and TN accounted for 87.54%of the variation in the litter decomposition rates.These results indicate that litter quality is the most important direct regulator of litter decomposition at the global scale.This data synthesis revealed significant relationships between litter decomposition rates and the combination of climatic factor(MAT)and litter quality(C:N,TN).The global-scale empirical relationships developed here are useful for a better understanding and modeling of the effects of litter quality and climatic factors on litter decomposition rates.展开更多
The Qilian Mountains(QM)possess a delicate vegetation ecosystem,amplifying the evident response of vegetation phenology to climate change.The relationship between changes in vegetation growth and climate remains compl...The Qilian Mountains(QM)possess a delicate vegetation ecosystem,amplifying the evident response of vegetation phenology to climate change.The relationship between changes in vegetation growth and climate remains complex.To this end,we used MODIS NDVI data to extract the phenological parameters of the vegetation including meadow(MDW),grassland(GSD),and alpine vegetation(ALV))in the QM from 2002 to 2021.Then,we employed path analysis to reveal the direct and indirect impacts of seasonal climate change on vegetation phenology.Additionally,we decomposed the vegetation phenology in a time series using the trigonometric seasonality,Box-Cox transformation,ARMA errors,and Trend Seasonal components model(TBATS).The findings showed a distinct pattern in the vegetation phenology of the QM,characterized by a progressive shift towards an earlier start of the growing season(SOS),a delayed end of the growing season(EOS),and an extended length of the growing season(LOS).The growth cycle of MDW,GSD,and ALV in the QM species is clearly defined.The SOS for MDW and GSD occurred earlier,mainly between late April and August,while the SOS for ALVs occurred between mid-May and mid-August,a one-month delay compared to the other vegetation.The EOS in MDW and GSD were concentrated between late August and April and early September and early January,respectively.Vegetation phenology exhibits distinct responses to seasonal temperature and precipitation patterns.The advancement and delay of SOS were mainly influenced by the direct effect of spring temperatures and precipitation,which affected 19.59%and 22.17%of the study area,respectively.The advancement and delay of EOS were mainly influenced by the direct effect of fall temperatures and precipitation,which affected 30.18%and 21.17%of the area,respectively.On the contrary,the direct effects of temperature and precipitation in summer and winter on vegetation phenology seem less noticeable and were mainly influenced by indirect effects.The indirect effect of winter precipitation is the main fac展开更多
Aims litter decomposition is a critical pathway linking the above-and belowground processes.However,factors underlying the local spatial variations in forest litter decomposition are still not fully addressed.We inves...Aims litter decomposition is a critical pathway linking the above-and belowground processes.However,factors underlying the local spatial variations in forest litter decomposition are still not fully addressed.We investigated leaf litter decomposition across con-trasting forest stands in central China,with objective to determine the spatial variations and controlling factors in forest floor leaf lit-ter decomposition in relation to changes in forest stands in a tem-perate forest ecosystem.Methods leaf litter decomposition was studied by using litterbag method across several typical forest stand types in baotianman Nature reserve,central China,including pure stands of Quercus aliena var.acuteserrata,Q.glandulifera var.brevipetiolata and Q.vari-abilis,respectively,and mixed pine/oak stands dominated by Pinus armandii and Q.aliena var.acuteserrata,as well as stands of pure Q.aliena var.acuteserrata trees ranging in stand age from~40 to>160 years.measurements were made on litter mass remaining and changes in litter chemistry during decomposition over a 2-year period,along with data collections on selective biotic and environmental factors.a reciprocal transplant experiment involv-ing Q.aliena var.acuteserrata and Q.variabilis was concurrently carried out to test the occurrence of‘home-field advantage(HFa)’in local forests when only considering contrasting oak tree spe-cies.Correlation analyses and path analyses were performed to identify the dominant drivers and their relative contributions to variations in leaf litter decomposition.Important findingssignificant variations were found in the rate of leaf litter decomposi-tion among stands of different tree species but not among stand age classes.The values of decay constant,k,varied from 0.62 in Q.aliena var.acuteserrata stands to 0.56 in Q.variabilis stands.The reciprocal litter transplant experiment showed that the rate of leaf litter decom-position was on average 5%slower in home-fields than on recipro-cal sites.Path analysis identified litter acid-unhydrolyzabl展开更多
基金supported by the Chinese Ecosystem Research Net(CERN)NSFC(30570350,40730102,30725006)+1 种基金by the Office of Science(BER),U.S.Department of Energy,Grant No.DE-FG03-99ER62800through the South Central Regional Center of the National Institute for Global Environmental Change under Cooperative Agreement No.DE-FC03-90ER61010.
文摘Aims We aim to construct a comprehensive global database of litter decomposition rate(k value)estimated by surface floor litterbags,and investigate the direct and indirect effects of impact factors such as geographic factors(latitude and altitude),climatic factors(mean annual tempePlrature,MAT;mean annual precipitation,MAP)and litter quality factors(the contents of N,P,K,Ca,Mg and C:N ratio,lignin:N ratio)on litter decomposition.Methods We compiled a large data set of litter decomposition rates(k values)from 110 research sites and conducted simple,multiple regression and path analyses to explore the relationship between the k values and impact factors at the global scale.Important findings The k values tended to decrease with latitude(LAT)and lignin content(LIGN)of litter but increased with temperature,precipitation and nutrient concentrations at the large spatial scale.Single factor such as climate,litter quality and geographic variable could not explain litter decomposition rates well.However,the combination of total nutrient(TN)elements and C:N accounted for 70.2%of the variation in the litter decomposition rates.The combination of LAT,MAT,C:N and TN accounted for 87.54%of the variation in the litter decomposition rates.These results indicate that litter quality is the most important direct regulator of litter decomposition at the global scale.This data synthesis revealed significant relationships between litter decomposition rates and the combination of climatic factor(MAT)and litter quality(C:N,TN).The global-scale empirical relationships developed here are useful for a better understanding and modeling of the effects of litter quality and climatic factors on litter decomposition rates.
基金financially supported by the National Natural Sciences Foundation of China(42261026,41971094,and 42161025)Gansu Science and Technology Research Project(22ZD6FA005)+1 种基金Higher Education Innovation Foundation of Education Department of Gansu Province(2022A-041)the open foundation of Xinjiang Key Laboratory of Water Cycle and Utilization in Arid Zone(XJYS0907-2023-01).
文摘The Qilian Mountains(QM)possess a delicate vegetation ecosystem,amplifying the evident response of vegetation phenology to climate change.The relationship between changes in vegetation growth and climate remains complex.To this end,we used MODIS NDVI data to extract the phenological parameters of the vegetation including meadow(MDW),grassland(GSD),and alpine vegetation(ALV))in the QM from 2002 to 2021.Then,we employed path analysis to reveal the direct and indirect impacts of seasonal climate change on vegetation phenology.Additionally,we decomposed the vegetation phenology in a time series using the trigonometric seasonality,Box-Cox transformation,ARMA errors,and Trend Seasonal components model(TBATS).The findings showed a distinct pattern in the vegetation phenology of the QM,characterized by a progressive shift towards an earlier start of the growing season(SOS),a delayed end of the growing season(EOS),and an extended length of the growing season(LOS).The growth cycle of MDW,GSD,and ALV in the QM species is clearly defined.The SOS for MDW and GSD occurred earlier,mainly between late April and August,while the SOS for ALVs occurred between mid-May and mid-August,a one-month delay compared to the other vegetation.The EOS in MDW and GSD were concentrated between late August and April and early September and early January,respectively.Vegetation phenology exhibits distinct responses to seasonal temperature and precipitation patterns.The advancement and delay of SOS were mainly influenced by the direct effect of spring temperatures and precipitation,which affected 19.59%and 22.17%of the study area,respectively.The advancement and delay of EOS were mainly influenced by the direct effect of fall temperatures and precipitation,which affected 30.18%and 21.17%of the area,respectively.On the contrary,the direct effects of temperature and precipitation in summer and winter on vegetation phenology seem less noticeable and were mainly influenced by indirect effects.The indirect effect of winter precipitation is the main fac
文摘Aims litter decomposition is a critical pathway linking the above-and belowground processes.However,factors underlying the local spatial variations in forest litter decomposition are still not fully addressed.We investigated leaf litter decomposition across con-trasting forest stands in central China,with objective to determine the spatial variations and controlling factors in forest floor leaf lit-ter decomposition in relation to changes in forest stands in a tem-perate forest ecosystem.Methods leaf litter decomposition was studied by using litterbag method across several typical forest stand types in baotianman Nature reserve,central China,including pure stands of Quercus aliena var.acuteserrata,Q.glandulifera var.brevipetiolata and Q.vari-abilis,respectively,and mixed pine/oak stands dominated by Pinus armandii and Q.aliena var.acuteserrata,as well as stands of pure Q.aliena var.acuteserrata trees ranging in stand age from~40 to>160 years.measurements were made on litter mass remaining and changes in litter chemistry during decomposition over a 2-year period,along with data collections on selective biotic and environmental factors.a reciprocal transplant experiment involv-ing Q.aliena var.acuteserrata and Q.variabilis was concurrently carried out to test the occurrence of‘home-field advantage(HFa)’in local forests when only considering contrasting oak tree spe-cies.Correlation analyses and path analyses were performed to identify the dominant drivers and their relative contributions to variations in leaf litter decomposition.Important findingssignificant variations were found in the rate of leaf litter decomposi-tion among stands of different tree species but not among stand age classes.The values of decay constant,k,varied from 0.62 in Q.aliena var.acuteserrata stands to 0.56 in Q.variabilis stands.The reciprocal litter transplant experiment showed that the rate of leaf litter decom-position was on average 5%slower in home-fields than on recipro-cal sites.Path analysis identified litter acid-unhydrolyzabl
