Background： Forest biodiversity is the foundation of many ecosystem services, and the effect of biodiversity on ecosystem functioning and processes （BEF） has been a central issue in biodiversity studies. Although m...Background： Forest biodiversity is the foundation of many ecosystem services, and the effect of biodiversity on ecosystem functioning and processes （BEF） has been a central issue in biodiversity studies. Although many hypotheses have been developed to interpret global gradients of biodiversity, there has not been complete agreement on mechanisms controlling biodiversity patterns and distributions. Differences may be due to limited observation data and inconsistencies of spatial scales in analysis. Methods： In this study, we take advantage of USDA Forest Service forest inventory and analysis （FIA） data for exploring regional forest biodiversity and BEF in New England forests. The FIA data provide detailed information of sampled plots and trees for the region, including 6000 FIA plots and more than 33,000 individual trees. Biodiversity models were used to analyze the data. Results： Tree species diversity increases from the north to the south at a rate about 2-3 species per latitudinal degree. Tree species diversity is better predicted by tree height than forest age or biomass. Very different distribution patterns of two common maple species, sugar maple （Acer sdcchorum） and red maple （Acer rubrum）, highlight the vulnerability of sugar maple and its potential replacement by red maple on New England landscapes. Red maple generally already outperforms sugar maple, and will likely and continuously benefit from a changing climate in New England. Conclusions： We conclude that forest structure （height） and resources （biomass） are more likely foundational characteristics supporting biodiversity rather than biodiversity determining forest productivity and/or biomass. The potential replacement of red maple for sugar maple in the New England areas could affect biodiversity and stability of forest ecosystem functioning because sugar maple plays important ecological roles distinct from red maple that are beneficial to other tree species in northern hardwood forests. Such a change may not affect f展开更多
美利坚独立革命的烽火首先从乡镇(波士顿、康科德、莱克星顿)点燃,并在乡镇联合行动中逐步形成燎原之势。1780年,在麻萨诸塞,新的邦宪条款的制定可以说是参加制宪大会(convention)的代表与他们各自所代表的乡镇民众不断讨论斟酌的结果,...美利坚独立革命的烽火首先从乡镇(波士顿、康科德、莱克星顿)点燃,并在乡镇联合行动中逐步形成燎原之势。1780年,在麻萨诸塞,新的邦宪条款的制定可以说是参加制宪大会(convention)的代表与他们各自所代表的乡镇民众不断讨论斟酌的结果,其中大、小乡镇之间围绕邦议会代表权、行政职位的设置、司法权的地位、邦与各乡镇之关系等现实议题的争论正是七年后费城合众国立宪大会的现实依据和学理基础。在丹尼尔.谢斯(Daniel Shays)及其率领的自耕农(Regulators)看来,麻萨诸塞政府已经成为东部商业利益集团谋取私利的工具,设在波士顿的新政府日趋脱离人民,走向专制,为此人民有责任揭竿而起,驱逐波士顿的权力精英,捍卫《独立宣言》的基本原则;同样,在南、北战争前夕的南部种植园主看来,联邦政府已被以林肯及其共和党代表的东北部利益集团所操控,美利坚国家的立国原则遭到破坏,而南部"美利坚联众国"(the Confederate States of America)的使命正是意在捍卫美利坚国父们的立国精神。为此,对乡镇的历史考察和现实观照无疑是推进我们理解当代美国政治和美利坚政治文化的关键环节,本文正是这一努力的初步尝试。展开更多
基金the project NRS-6“Climate,Fire,and Carbon Cycle Sciences”supported by the USDA Forest ServiceBeijing Forestry University for covering the trip to the conference and generous conference venue facilitating this study
文摘Background： Forest biodiversity is the foundation of many ecosystem services, and the effect of biodiversity on ecosystem functioning and processes （BEF） has been a central issue in biodiversity studies. Although many hypotheses have been developed to interpret global gradients of biodiversity, there has not been complete agreement on mechanisms controlling biodiversity patterns and distributions. Differences may be due to limited observation data and inconsistencies of spatial scales in analysis. Methods： In this study, we take advantage of USDA Forest Service forest inventory and analysis （FIA） data for exploring regional forest biodiversity and BEF in New England forests. The FIA data provide detailed information of sampled plots and trees for the region, including 6000 FIA plots and more than 33,000 individual trees. Biodiversity models were used to analyze the data. Results： Tree species diversity increases from the north to the south at a rate about 2-3 species per latitudinal degree. Tree species diversity is better predicted by tree height than forest age or biomass. Very different distribution patterns of two common maple species, sugar maple （Acer sdcchorum） and red maple （Acer rubrum）, highlight the vulnerability of sugar maple and its potential replacement by red maple on New England landscapes. Red maple generally already outperforms sugar maple, and will likely and continuously benefit from a changing climate in New England. Conclusions： We conclude that forest structure （height） and resources （biomass） are more likely foundational characteristics supporting biodiversity rather than biodiversity determining forest productivity and/or biomass. The potential replacement of red maple for sugar maple in the New England areas could affect biodiversity and stability of forest ecosystem functioning because sugar maple plays important ecological roles distinct from red maple that are beneficial to other tree species in northern hardwood forests. Such a change may not affect f
文摘美利坚独立革命的烽火首先从乡镇(波士顿、康科德、莱克星顿)点燃,并在乡镇联合行动中逐步形成燎原之势。1780年,在麻萨诸塞,新的邦宪条款的制定可以说是参加制宪大会(convention)的代表与他们各自所代表的乡镇民众不断讨论斟酌的结果,其中大、小乡镇之间围绕邦议会代表权、行政职位的设置、司法权的地位、邦与各乡镇之关系等现实议题的争论正是七年后费城合众国立宪大会的现实依据和学理基础。在丹尼尔.谢斯(Daniel Shays)及其率领的自耕农(Regulators)看来,麻萨诸塞政府已经成为东部商业利益集团谋取私利的工具,设在波士顿的新政府日趋脱离人民,走向专制,为此人民有责任揭竿而起,驱逐波士顿的权力精英,捍卫《独立宣言》的基本原则;同样,在南、北战争前夕的南部种植园主看来,联邦政府已被以林肯及其共和党代表的东北部利益集团所操控,美利坚国家的立国原则遭到破坏,而南部"美利坚联众国"(the Confederate States of America)的使命正是意在捍卫美利坚国父们的立国精神。为此,对乡镇的历史考察和现实观照无疑是推进我们理解当代美国政治和美利坚政治文化的关键环节,本文正是这一努力的初步尝试。
