物种多样性地理分布格局及其成因是生物地理学和宏观生态学研究的核心问题之一。为了解释物种多样性的分布格局,人们提出了多种假说,其中讨论最多的是能量假说。该假说认为,物种多样性的变化受能量控制。根据能量的不同形式及其对物种...物种多样性地理分布格局及其成因是生物地理学和宏观生态学研究的核心问题之一。为了解释物种多样性的分布格局,人们提出了多种假说,其中讨论最多的是能量假说。该假说认为,物种多样性的变化受能量控制。根据能量的不同形式及其对物种多样性的影响机制,能量假说包括以下几种形式:生产力假说(productivity hypothesis)、水分—能量动态假说(water-energy dynamic hypothesis)、环境能量假说(ambientenergy hypothesis)、寒冷忍耐假说(freezing tolerance hypothesis)以及生态学代谢假说(metabolic theory of ecology,MTE)。本文系统介绍了每种能量假说的含义、所使用的能量形式及表征变量,以及对物种多样性的影响机制,并对不同形式的能量假说进行了比较,在此基础上,分析了每种能量假说的优点和缺点以及各自面临的问题。展开更多
Understanding large-scale patterns of biodiversity and their drivers remains central in ecology.Many hypotheses have been proposed,including hydrothermal dynamic hypothesis,tropical niche conservatism hypothesis,Janze...Understanding large-scale patterns of biodiversity and their drivers remains central in ecology.Many hypotheses have been proposed,including hydrothermal dynamic hypothesis,tropical niche conservatism hypothesis,Janzen’s hypothesis and a combination model containing energy,water,seasonality and habitat heterogeneity.Yet,their relative contributions to groups with different lifeforms and range sizes remain controversial,which have limited our ability to understand the general mechanisms underlying species richness patterns.Here we evaluated how lifeforms and species range sizes influenced the relative contributions of these three hypotheses to species richness patterns of a tropical family Moraceae.The distribution data of Moraceae species at a spatial resolution of 50 km×50 km and their lifeforms(i.e.shrubs,small trees and large trees)were compiled.The species richness patterns were estimated for the entire family,different life forms and species with different range sizes separately.The effects of environmental variables on species richness were analyzed,and relative contributions of different hypotheses were evaluated across life forms and species range size groups.The species richness patterns were consistent across different species groups and the species richness was the highest in Sichuan,Guangzhou and Hainan provinces,making these provinces the hotspots of this family.Climate seasonality is the primary factor in determining richness variation of Moraceae.The best combination model gave the largest explanatory power for Moraceae species richness across each group of range size and life forms followed by the hydrothermal dynamic hypothesis,Janzen’s hypothesis and tropical niche conservatism hypothesis.All these models has a large shared effects but a low independent effect(<5%),except rare species.These findings suggest unique patterns and mechanisms underlying rare species richness and provide a theoretical basis for protection of the Moraceae species in China.展开更多
Quantifying stoichiometry of crop N and P acquisition(i.e.removal from farmland)under different agronomic practices is essential for understanding nutrient budgets and optimizing N and P fertilizer application in agro...Quantifying stoichiometry of crop N and P acquisition(i.e.removal from farmland)under different agronomic practices is essential for understanding nutrient budgets and optimizing N and P fertilizer application in agroecosystems.It is not clear how plant N and P uptake and N:P stoichiometry vary between monoculture and intercropping throughout an entire growing season under different N fertilization and mulching practices.Here,we addressed how plant interspecific competition for nutrients have affected the temporal dynamics of crop N and P uptake(and N:P ratios)in five cropping systems(wheat,maize and barley monocultures,and wheat/maize and barley/maize intercropping),under two N levels(0 and 225 kg N ha^(−1))and two maize mulching treatments(with and without).Wheat and barley had greater N and P competitive ability than maize,leading to an increase in N and P uptake of wheat and barley and a decrease in N and P uptake of maize during co-growth stages in intercropping.N:P ratios of three crop species decreased with plant growth.Crop-level N:P ratios were either not affected by intercropping or did not change consistently with N fertilization while film mulching decreased maize N:P ratios.Community-level N:P ratios of the two intercrops were different from those of the corresponding monoculture at maturity.Because(i)the proportion of N and P removal from intercropping differs from monocultures,and(ii)N and P uptake by crops is decoupled under N fertilization and mulching,these findings may have practical implications for the nutrient budget of intercropping systems.展开更多
文摘物种多样性地理分布格局及其成因是生物地理学和宏观生态学研究的核心问题之一。为了解释物种多样性的分布格局,人们提出了多种假说,其中讨论最多的是能量假说。该假说认为,物种多样性的变化受能量控制。根据能量的不同形式及其对物种多样性的影响机制,能量假说包括以下几种形式:生产力假说(productivity hypothesis)、水分—能量动态假说(water-energy dynamic hypothesis)、环境能量假说(ambientenergy hypothesis)、寒冷忍耐假说(freezing tolerance hypothesis)以及生态学代谢假说(metabolic theory of ecology,MTE)。本文系统介绍了每种能量假说的含义、所使用的能量形式及表征变量,以及对物种多样性的影响机制,并对不同形式的能量假说进行了比较,在此基础上,分析了每种能量假说的优点和缺点以及各自面临的问题。
基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31000000)National Key Research Development Program of China(2017YFA0605101,2017YFC0505203)National Natural Science Foundation of China(32C125026,31988102,31770566).
文摘Understanding large-scale patterns of biodiversity and their drivers remains central in ecology.Many hypotheses have been proposed,including hydrothermal dynamic hypothesis,tropical niche conservatism hypothesis,Janzen’s hypothesis and a combination model containing energy,water,seasonality and habitat heterogeneity.Yet,their relative contributions to groups with different lifeforms and range sizes remain controversial,which have limited our ability to understand the general mechanisms underlying species richness patterns.Here we evaluated how lifeforms and species range sizes influenced the relative contributions of these three hypotheses to species richness patterns of a tropical family Moraceae.The distribution data of Moraceae species at a spatial resolution of 50 km×50 km and their lifeforms(i.e.shrubs,small trees and large trees)were compiled.The species richness patterns were estimated for the entire family,different life forms and species with different range sizes separately.The effects of environmental variables on species richness were analyzed,and relative contributions of different hypotheses were evaluated across life forms and species range size groups.The species richness patterns were consistent across different species groups and the species richness was the highest in Sichuan,Guangzhou and Hainan provinces,making these provinces the hotspots of this family.Climate seasonality is the primary factor in determining richness variation of Moraceae.The best combination model gave the largest explanatory power for Moraceae species richness across each group of range size and life forms followed by the hydrothermal dynamic hypothesis,Janzen’s hypothesis and tropical niche conservatism hypothesis.All these models has a large shared effects but a low independent effect(<5%),except rare species.These findings suggest unique patterns and mechanisms underlying rare species richness and provide a theoretical basis for protection of the Moraceae species in China.
基金funded by the National Key Research and Development Program of China(2016YFD0300202)the Natural Science Foundation of China(31971450,31500348,31430014)Chinese Universities Scientific Fund(2020TC051)and the European Research Council Synergy grant(ERC-SyG-2013-610028,IMBALANCE-P).
文摘Quantifying stoichiometry of crop N and P acquisition(i.e.removal from farmland)under different agronomic practices is essential for understanding nutrient budgets and optimizing N and P fertilizer application in agroecosystems.It is not clear how plant N and P uptake and N:P stoichiometry vary between monoculture and intercropping throughout an entire growing season under different N fertilization and mulching practices.Here,we addressed how plant interspecific competition for nutrients have affected the temporal dynamics of crop N and P uptake(and N:P ratios)in five cropping systems(wheat,maize and barley monocultures,and wheat/maize and barley/maize intercropping),under two N levels(0 and 225 kg N ha^(−1))and two maize mulching treatments(with and without).Wheat and barley had greater N and P competitive ability than maize,leading to an increase in N and P uptake of wheat and barley and a decrease in N and P uptake of maize during co-growth stages in intercropping.N:P ratios of three crop species decreased with plant growth.Crop-level N:P ratios were either not affected by intercropping or did not change consistently with N fertilization while film mulching decreased maize N:P ratios.Community-level N:P ratios of the two intercrops were different from those of the corresponding monoculture at maturity.Because(i)the proportion of N and P removal from intercropping differs from monocultures,and(ii)N and P uptake by crops is decoupled under N fertilization and mulching,these findings may have practical implications for the nutrient budget of intercropping systems.
