Native trees play important roles in urban forestry, such as a deep cultural background, a strong ecological adaptability, a high performance-cost ratio and a convenient management. But now there are some difficulties...Native trees play important roles in urban forestry, such as a deep cultural background, a strong ecological adaptability, a high performance-cost ratio and a convenient management. But now there are some difficulties in native trees’ utilization and popularization dueto few study on landscape plant. In order to seek an abnormal and artificial landscaping and to produce an effective resultas soon as possible, native and foreign plants can be properly used as an available resource by improving their technological level and emphasizing natural balance. Then Chinese classic culture and green economics can be combined with beautiful forestry by implementing urban sustainable development.展开更多
Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions.Annual herbs are pioneers adapted to these areas;however,little is known about the resp...Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions.Annual herbs are pioneers adapted to these areas;however,little is known about the responses of their seeds and infructescence,and the germination of their offspring to these limited water and soil resources.In this study,we investigated how the seed and fruiting phenology plasticity and offspring seed germination rates of two annual Asteraceae herbs(Xanthium sibiricum and Bidens pilosa)respond to the harsh karst soil environment,by assessing the seed number,seed biomass and offspring seed germination rate.X.sibiricum and B.pilosa were grown under three soil thicknesses and three water availability levels in a full two-way randomized block design.The key results were as follows:(1)The number and biomass of progenies(infructescence and seeds)of X.sibiricum decreased with the decline of soil thickness and/or water availability(P<0.05).The infructescence and seed biomass of B.pilosa increased with the decline of water availability.(2)Seed quantity and seed biomass of X.sibiricum showed no correlation after their parents experienced resource reductions.A significant positive relationship between seed number and seed biomass was observed in B.pilosa(P<0.05).(3)The offspring seed germination rate of X.sibiricum did not change with the decrease of soil thickness under three levels of water treatment.However,the offspring seed germination rate of B.pilosa decreased significantly with the decrease of soil thickness under the control water level(P<0.05).The results show that X.sibiricum tends to improve its competitiveness by ensuring the quantity and quality of offspring in order to adapt to the shallow karst soils and dry karst habitats.In contrast,B.pilosa adapts to the unfavorable karst habitats by a risk-sharing strategy.B.pilosa produces more and bigger seeds to in an attempt to expand its survival range and escape from the unfavorable living environment,but this results in a lower seed number and germination rate of its progeny under the karst soil resource reduction.展开更多
The land fallow policy was adopted by central and local governments to encourage the abandonment of water-intensive crops, such as winter wheat, in groundwater over-exploited areas. At the same time, since the 1990s, ...The land fallow policy was adopted by central and local governments to encourage the abandonment of water-intensive crops, such as winter wheat, in groundwater over-exploited areas. At the same time, since the 1990s, many households in the North China Plain （NCP） have chosen to replace the winter wheat and summer maize double-cropping system with the spring maize single-cropping system. Therefore, it is crucial to identify target land parcels for winter wheat abandonment and to design reasonable and proper standards for ecological compensation prior to the implementation of the land fallow policy in the NCP. In this study, multi-level Iogit models were used with household survey data in order to detect determinants across land parcel, household and village levels on household cropping system decisions; the opportunity costs for winter wheat abandonment were also calculated using cost-benefit analysis. The results show that： （1） land quality and irrigation condition at parcel level are two essential elements influencing household cropping system decisions. Nearly 70% of the total area of poor land and more than 90% of the total area of unirrigated land has suffered winter wheat abandonment. Target land parcels for the land fallow policy should be those that are irrigated and of high quality. （2） There were no significant differences between net profits from spring maize and summer maize under similar farming conditions, and the opportunity cost for winter wheat abandonment should be equal to the net profit of winter wheat. （3） The primary purpose of the land fallow policy is to induce groundwater recovery and restoration as a preliminary stage. A higher level of 350 yuan/mu is recommended as subsidy for ecological compensation at this stage. Later, the primary purpose of the policy should be a transition to a balance between exploitation and supplementation of water resources, and a lower level of 280 yuan/mu is recommended as a subsidy at this stage.展开更多
文摘Native trees play important roles in urban forestry, such as a deep cultural background, a strong ecological adaptability, a high performance-cost ratio and a convenient management. But now there are some difficulties in native trees’ utilization and popularization dueto few study on landscape plant. In order to seek an abnormal and artificial landscaping and to produce an effective resultas soon as possible, native and foreign plants can be properly used as an available resource by improving their technological level and emphasizing natural balance. Then Chinese classic culture and green economics can be combined with beautiful forestry by implementing urban sustainable development.
基金The Chongqing Natural Science Foundation(cstc2020jcyj-msxmX0244)The Special Funds for Basic Scientific Research in Central Universities(XDJK2020B037)The National Natural Science Foundation of China(31500399)。
文摘Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions.Annual herbs are pioneers adapted to these areas;however,little is known about the responses of their seeds and infructescence,and the germination of their offspring to these limited water and soil resources.In this study,we investigated how the seed and fruiting phenology plasticity and offspring seed germination rates of two annual Asteraceae herbs(Xanthium sibiricum and Bidens pilosa)respond to the harsh karst soil environment,by assessing the seed number,seed biomass and offspring seed germination rate.X.sibiricum and B.pilosa were grown under three soil thicknesses and three water availability levels in a full two-way randomized block design.The key results were as follows:(1)The number and biomass of progenies(infructescence and seeds)of X.sibiricum decreased with the decline of soil thickness and/or water availability(P<0.05).The infructescence and seed biomass of B.pilosa increased with the decline of water availability.(2)Seed quantity and seed biomass of X.sibiricum showed no correlation after their parents experienced resource reductions.A significant positive relationship between seed number and seed biomass was observed in B.pilosa(P<0.05).(3)The offspring seed germination rate of X.sibiricum did not change with the decrease of soil thickness under three levels of water treatment.However,the offspring seed germination rate of B.pilosa decreased significantly with the decrease of soil thickness under the control water level(P<0.05).The results show that X.sibiricum tends to improve its competitiveness by ensuring the quantity and quality of offspring in order to adapt to the shallow karst soils and dry karst habitats.In contrast,B.pilosa adapts to the unfavorable karst habitats by a risk-sharing strategy.B.pilosa produces more and bigger seeds to in an attempt to expand its survival range and escape from the unfavorable living environment,but this results in a lower seed number and germination rate of its progeny under the karst soil resource reduction.
基金National Natural Science Foundation of China,No.41571095,No.41271119
文摘The land fallow policy was adopted by central and local governments to encourage the abandonment of water-intensive crops, such as winter wheat, in groundwater over-exploited areas. At the same time, since the 1990s, many households in the North China Plain （NCP） have chosen to replace the winter wheat and summer maize double-cropping system with the spring maize single-cropping system. Therefore, it is crucial to identify target land parcels for winter wheat abandonment and to design reasonable and proper standards for ecological compensation prior to the implementation of the land fallow policy in the NCP. In this study, multi-level Iogit models were used with household survey data in order to detect determinants across land parcel, household and village levels on household cropping system decisions; the opportunity costs for winter wheat abandonment were also calculated using cost-benefit analysis. The results show that： （1） land quality and irrigation condition at parcel level are two essential elements influencing household cropping system decisions. Nearly 70% of the total area of poor land and more than 90% of the total area of unirrigated land has suffered winter wheat abandonment. Target land parcels for the land fallow policy should be those that are irrigated and of high quality. （2） There were no significant differences between net profits from spring maize and summer maize under similar farming conditions, and the opportunity cost for winter wheat abandonment should be equal to the net profit of winter wheat. （3） The primary purpose of the land fallow policy is to induce groundwater recovery and restoration as a preliminary stage. A higher level of 350 yuan/mu is recommended as subsidy for ecological compensation at this stage. Later, the primary purpose of the policy should be a transition to a balance between exploitation and supplementation of water resources, and a lower level of 280 yuan/mu is recommended as a subsidy at this stage.
