[ Objective] This study aimed to explore the morphological characteristics and nutrient content of f＇me roots of 2-year-old and 3-year-old Euca/yptus grand/s plantation and investigate the correlation. [ Method] Fine...[ Objective] This study aimed to explore the morphological characteristics and nutrient content of f＇me roots of 2-year-old and 3-year-old Euca/yptus grand/s plantation and investigate the correlation. [ Method] Fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation were collected as experimental materials, to determine the root diameter （D）, root length （L）, specific root length （SRL） and contents of major nutrient elements N, P, K, Ca, Mg and C of fine roots （level 1 -5）, study the morphological characteristics and major nutrient element content and investigate the correlation. [ Result] The results showed that morphological differences of fine roots （ level 1 - 5 ） of Eucalyptus grandis plantation were great with the increase of root order, to be specific, D and L increased and SRL decreased with the increasing root order; SRL, L and D of 3-year-old Eucalyptus grauclis plantation were greater than those of 2-year-old Euca/yptus grand/s plantation. Contents of N, Ca, Mg and C of fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation showed consistent orders with the increase of root order： N and Mg contents were reduced, while Ca and C contents were enhanced; P and K contents varied with different forest ages; both 2-year-old and 3-year- old Eucalyptus grandis showed an order of C 〉 K 〉 Ca （Mg） 〉 N. Major nutrient element content and morphological characteristics of Eucalyptus grand/s fine roots （level 1 -5 ） were extremely significantly correlated （P 〈0.01 ）, SRL, L and D could be adopted as reference indices to evaluate nutrient status of Eucalyptus grand/s. Required nutrients and fine root morphology of Eucalyptus grandis plantation changed with the increase of forest age, and the nutrient cycling and energy flow patterns also changed; major nutrient dements in fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation transferred in a different order from the growth order, therefore N fertilizer could be applied to improve the growth of fine roots. [ Condusion] This study laid the foundation for understanding the fine root morphology and nutrient variation pattern of Eucalyptus grandis plantation and enriching the response and adaptation mechanism theory of roots to environment, pos- sessing important reference significance for the sustainable development of Eucalyptus grand/s plantation.展开更多
Underground natural gas storage(UNGS)is an important part of the natural gas supply system to ensure a balanced energy supply.The surface system,as an important part of the gas storage,undertakes the functions of gas ...Underground natural gas storage(UNGS)is an important part of the natural gas supply system to ensure a balanced energy supply.The surface system,as an important part of the gas storage,undertakes the functions of gas injection and gas production of the gas storage,and its investment economy is of vital importance.In fact,the UNGS surface pipeline network has two-way injection and production characteristics,which is different from the one-way production characteristics of conventional oil&gas gathering and transportation systems.This paper takes the minimum investment of the pipeline network as the objective function,considers the gas injection and gas withdrawal flow conditions and esablishes a mixed integer non-linear programming model(MINLP)for the surface pipeline network of the UNGS to optimize its pipeline layout and diameter parameters.Constraints including the well affiliation,the number of stations,the gathering radius,the processing capacity and the flow/pressure equilibrium equations,are also taken into consideration.Taking an UNGS in China as an example,the results of the optimal structure and diameter of the pipeline network,as well as the pipe flow,node pressure,and maximum/minimum flowrate during gas injection and gas withdrawal are obtained.Finally,the effects of constraints such as processing capacity and radius on the structure layout and investment of the UNGS are analyzed,verifying the reliability and effectiveness of the model.展开更多
基金Supported by Key Project of the Education Department of Sichuan Province(09ZA079)College-level Fund of Sichuan Agricultural University(64070113)+3 种基金National Science and Technology Support Program of China(2011BAC09B05)Science and Technology Support Program of Sichuan Province(2010NZ0049)National Natural Science Foundation of China(30771717)Fund for Forest Tree Germplasm Resources in the Upper Reaches of the Yangtze River and Breeding Technology Innovation Team(00370503)
文摘[ Objective] This study aimed to explore the morphological characteristics and nutrient content of f＇me roots of 2-year-old and 3-year-old Euca/yptus grand/s plantation and investigate the correlation. [ Method] Fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation were collected as experimental materials, to determine the root diameter （D）, root length （L）, specific root length （SRL） and contents of major nutrient elements N, P, K, Ca, Mg and C of fine roots （level 1 -5）, study the morphological characteristics and major nutrient element content and investigate the correlation. [ Result] The results showed that morphological differences of fine roots （ level 1 - 5 ） of Eucalyptus grandis plantation were great with the increase of root order, to be specific, D and L increased and SRL decreased with the increasing root order; SRL, L and D of 3-year-old Eucalyptus grauclis plantation were greater than those of 2-year-old Euca/yptus grand/s plantation. Contents of N, Ca, Mg and C of fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation showed consistent orders with the increase of root order： N and Mg contents were reduced, while Ca and C contents were enhanced; P and K contents varied with different forest ages; both 2-year-old and 3-year- old Eucalyptus grandis showed an order of C 〉 K 〉 Ca （Mg） 〉 N. Major nutrient element content and morphological characteristics of Eucalyptus grand/s fine roots （level 1 -5 ） were extremely significantly correlated （P 〈0.01 ）, SRL, L and D could be adopted as reference indices to evaluate nutrient status of Eucalyptus grand/s. Required nutrients and fine root morphology of Eucalyptus grandis plantation changed with the increase of forest age, and the nutrient cycling and energy flow patterns also changed; major nutrient dements in fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation transferred in a different order from the growth order, therefore N fertilizer could be applied to improve the growth of fine roots. [ Condusion] This study laid the foundation for understanding the fine root morphology and nutrient variation pattern of Eucalyptus grandis plantation and enriching the response and adaptation mechanism theory of roots to environment, pos- sessing important reference significance for the sustainable development of Eucalyptus grand/s plantation.
基金This work was part of the program“Study on the optimization method and architecture of oil and gas pipeline network design in discrete space and network space”,funded by the National Natural Science Foundation of China,grant number 51704253.The authors are grateful to all study participants.
文摘Underground natural gas storage(UNGS)is an important part of the natural gas supply system to ensure a balanced energy supply.The surface system,as an important part of the gas storage,undertakes the functions of gas injection and gas production of the gas storage,and its investment economy is of vital importance.In fact,the UNGS surface pipeline network has two-way injection and production characteristics,which is different from the one-way production characteristics of conventional oil&gas gathering and transportation systems.This paper takes the minimum investment of the pipeline network as the objective function,considers the gas injection and gas withdrawal flow conditions and esablishes a mixed integer non-linear programming model(MINLP)for the surface pipeline network of the UNGS to optimize its pipeline layout and diameter parameters.Constraints including the well affiliation,the number of stations,the gathering radius,the processing capacity and the flow/pressure equilibrium equations,are also taken into consideration.Taking an UNGS in China as an example,the results of the optimal structure and diameter of the pipeline network,as well as the pipe flow,node pressure,and maximum/minimum flowrate during gas injection and gas withdrawal are obtained.Finally,the effects of constraints such as processing capacity and radius on the structure layout and investment of the UNGS are analyzed,verifying the reliability and effectiveness of the model.
