The Chikugo Model is used to estimate radiative dryness indexes (RDI) and net primary productivity (NPP) of vegetation zones in China by calculating cli-matic parameters. That provides the water-heat equilibrium condi...The Chikugo Model is used to estimate radiative dryness indexes (RDI) and net primary productivity (NPP) of vegetation zones in China by calculating cli-matic parameters. That provides the water-heat equilibrium condition, potential primary production for natural vegetation in various vegetation zones, and their geographical distribution pattern. That could be used as the basis for study the effect of global climate change on ecosystems.展开更多
Understanding the relationship between the timing of N fertilizer applications and crop primary production is crucial for achieving high yield and N use efifciency in agriculture. This study investigated the effects o...Understanding the relationship between the timing of N fertilizer applications and crop primary production is crucial for achieving high yield and N use efifciency in agriculture. This study investigated the effects of starting-N plus topdressing N applications （as compared to the common practice of all basal application） on soybean photosynthetic capacity under different planting densities. A ifeld experiment was conducted in two growing seasons （2011 and 2012）, and the soybean （Glycine max L. Merrill） cultivar was Dongnong 52, three planting densities （20, 25 and 30 plants m-2）, and four N fertilizer application patterns （all N fertilizer of 6 g N m-2 as basal fertilizer, all N fertilizer as topdressing at beginning pod stage （R3）, 1.8 g N m-2 as basal fertilizer and 4.2 g N m-2 as topdressing at stage R3 and full pod stage （R4）, respectively）. The results indicated that under the same planting density, compared to applying all N as basal fertilizer, the application of starter-N plus topdressing N substantially reduced the rate of pod abscission, and enhanced leaf area index （LAI） signiifcantly at beginning seed stage （R5） （P〈0.05）, net assimilation rate （NAR） during stages R4-full seed stage （R6） （P〈0.05）, contribution rate of post-seed iflling assimilate to seed （CPA） （P〈0.05）, and yield （P〈0.05）. Applying topdressing N at stage R4 resulted in higher net primary production and yield than applying topdressing N at stage R3. When applying starter-N plus topdressing N at planting density of 25 plants m-2, LAI after stage R5 and NAR after stage R4 were increased by 5.92-16.3%（P〈0.05） and 13.7-26.6%（P〈0.05） with the planting density of 20 plants m-2, respectively, and yield was 8.46-14.0%（P〈0.05） higher than that under 20 plants m-2. When planting density increased to 30 plants m-2, only LAI during stages R4-R5 and NAR during stages R4-R5 increased by applying starter-N plus topdressing N, while the other indexes declined. Overall, results of this study demonstrated that applying starter-N plus topdressing N could signiifcantly enhance soybean photosynthetic capacity after stage R5 at planting density of 25 plants m-2.展开更多
Petri net language is a powerful tool for describing dynamic behaviors of physical systems. However, it is not easy to obtain the language expression for a given Petri net especially a structure-complex net. In this p...Petri net language is a powerful tool for describing dynamic behaviors of physical systems. However, it is not easy to obtain the language expression for a given Petri net especially a structure-complex net. In this paper, we first analyze the behaviors of S-nets, which are structure-simple. With the decomposition method based on a given index function on the place set, a given structure-complex Petri net can be decomposed into a set of structure-simple S-nets. With the language relationships between the original system and the decomposed subnets, an algorithm to obtain the language expression of a given structure-complex net system is presented, which benefits the analysis of physical systems based on the Petri net language.展开更多
The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are sti...The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are still controversial. We selected 717 grassland sites with ANPP and mean annual precipitation(MAP) data from 40 publications to characterize the relationships ANPP–MAP and PUE–MAP across different grassland types. The MAP and ANPP showed large variations across all grassland types, ranging from 69 to 2335 mm and 4.3 to 1706 g m^(-2), respectively. The global maximum PUE ranged from 0.19 to 1.49 g m^(-2) mm^(-1) with a unimodal pattern. Analysis using the sigmoid function explained the ANPP–MAP relationship best at the global scale. The gradient of the ANPP–MAP graph was small for arid and semi-arid sites(MAP <400 mm). This study improves our understanding of the relationship between ANPP and MAP across dry grassland ecosystems. It provides new perspectives on the prediction and modeling of variations in the ANPP for different grassland types along precipitation gradients.展开更多
Using " chain-based and constant-based" two-step method,this paper measured Paasche net barter terms of trade index for SinoAustralian agricultural products from 2001 to 2013,and further calculated contribut...Using " chain-based and constant-based" two-step method,this paper measured Paasche net barter terms of trade index for SinoAustralian agricultural products from 2001 to 2013,and further calculated contribution of each category of agricultural products to changes in overall net barter terms of trade. The results showed that since 2001,the overall net barter terms of trade for Sino-Australian agricultural products fluctuated between deterioration and improvement. In 2013,the net barter terms of trade index was 1. 02,and its improvement is not significant. From 2001 to 2013,the net barter terms of trade for Sino-Australian agricultural products improved about 16. 44%,which dominated by the category 0 agricultural products whose influence degree is 6 times and 28 times the degree of category 4 and category 1. In years when the net barter terms of trade for Sino-Australian agricultural products deteriorated,category 2 agricultural products were the root cause for the deterioration.展开更多
文摘The Chikugo Model is used to estimate radiative dryness indexes (RDI) and net primary productivity (NPP) of vegetation zones in China by calculating cli-matic parameters. That provides the water-heat equilibrium condition, potential primary production for natural vegetation in various vegetation zones, and their geographical distribution pattern. That could be used as the basis for study the effect of global climate change on ecosystems.
基金financially supported by the Special Fund for Agro-Scientific Research in the Public Interest, China (201103003)the Key Technologies R&D Program of China during the 12th Five-Year Plan period (2012BAD20B04)
文摘Understanding the relationship between the timing of N fertilizer applications and crop primary production is crucial for achieving high yield and N use efifciency in agriculture. This study investigated the effects of starting-N plus topdressing N applications （as compared to the common practice of all basal application） on soybean photosynthetic capacity under different planting densities. A ifeld experiment was conducted in two growing seasons （2011 and 2012）, and the soybean （Glycine max L. Merrill） cultivar was Dongnong 52, three planting densities （20, 25 and 30 plants m-2）, and four N fertilizer application patterns （all N fertilizer of 6 g N m-2 as basal fertilizer, all N fertilizer as topdressing at beginning pod stage （R3）, 1.8 g N m-2 as basal fertilizer and 4.2 g N m-2 as topdressing at stage R3 and full pod stage （R4）, respectively）. The results indicated that under the same planting density, compared to applying all N as basal fertilizer, the application of starter-N plus topdressing N substantially reduced the rate of pod abscission, and enhanced leaf area index （LAI） signiifcantly at beginning seed stage （R5） （P〈0.05）, net assimilation rate （NAR） during stages R4-full seed stage （R6） （P〈0.05）, contribution rate of post-seed iflling assimilate to seed （CPA） （P〈0.05）, and yield （P〈0.05）. Applying topdressing N at stage R4 resulted in higher net primary production and yield than applying topdressing N at stage R3. When applying starter-N plus topdressing N at planting density of 25 plants m-2, LAI after stage R5 and NAR after stage R4 were increased by 5.92-16.3%（P〈0.05） and 13.7-26.6%（P〈0.05） with the planting density of 20 plants m-2, respectively, and yield was 8.46-14.0%（P〈0.05） higher than that under 20 plants m-2. When planting density increased to 30 plants m-2, only LAI during stages R4-R5 and NAR during stages R4-R5 increased by applying starter-N plus topdressing N, while the other indexes declined. Overall, results of this study demonstrated that applying starter-N plus topdressing N could signiifcantly enhance soybean photosynthetic capacity after stage R5 at planting density of 25 plants m-2.
基金This work was supported by the National Natural Science Foundation of China(No.60173053&No.60274063)the Excellent Young Scientist Foundation of Shandong Province of China(No.02BS069).
文摘Petri net language is a powerful tool for describing dynamic behaviors of physical systems. However, it is not easy to obtain the language expression for a given Petri net especially a structure-complex net. In this paper, we first analyze the behaviors of S-nets, which are structure-simple. With the decomposition method based on a given index function on the place set, a given structure-complex Petri net can be decomposed into a set of structure-simple S-nets. With the language relationships between the original system and the decomposed subnets, an algorithm to obtain the language expression of a given structure-complex net system is presented, which benefits the analysis of physical systems based on the Petri net language.
基金jointly funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20020401)the Young Foundation of Institute of Mountain Hazard and Environment(SDS-QN-1702)National Natural Science Foundation of China(Grant No.41571205)
文摘The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are still controversial. We selected 717 grassland sites with ANPP and mean annual precipitation(MAP) data from 40 publications to characterize the relationships ANPP–MAP and PUE–MAP across different grassland types. The MAP and ANPP showed large variations across all grassland types, ranging from 69 to 2335 mm and 4.3 to 1706 g m^(-2), respectively. The global maximum PUE ranged from 0.19 to 1.49 g m^(-2) mm^(-1) with a unimodal pattern. Analysis using the sigmoid function explained the ANPP–MAP relationship best at the global scale. The gradient of the ANPP–MAP graph was small for arid and semi-arid sites(MAP <400 mm). This study improves our understanding of the relationship between ANPP and MAP across dry grassland ecosystems. It provides new perspectives on the prediction and modeling of variations in the ANPP for different grassland types along precipitation gradients.
基金Supported by"Industrial Economic Research of National Technology System for Wool Sheep and Cashmere Goat Industries"of the Ministry of Agriculture and the Ministry of Finance(CARS-40-20)Chinese Universities Scientific Fund(2015RW007)
文摘Using " chain-based and constant-based" two-step method,this paper measured Paasche net barter terms of trade index for SinoAustralian agricultural products from 2001 to 2013,and further calculated contribution of each category of agricultural products to changes in overall net barter terms of trade. The results showed that since 2001,the overall net barter terms of trade for Sino-Australian agricultural products fluctuated between deterioration and improvement. In 2013,the net barter terms of trade index was 1. 02,and its improvement is not significant. From 2001 to 2013,the net barter terms of trade for Sino-Australian agricultural products improved about 16. 44%,which dominated by the category 0 agricultural products whose influence degree is 6 times and 28 times the degree of category 4 and category 1. In years when the net barter terms of trade for Sino-Australian agricultural products deteriorated,category 2 agricultural products were the root cause for the deterioration.
