نتایج جستجو برای: terrestrial ecosystems

تعداد نتایج: 76121  

Journal: :Global Biogeochemical Cycles 1999

2010
Daniel J. Hayes A. David McGuire David W. Kicklighter Todd J. Burnside Jerry M. Melillo

Recent changes in climate, disturbance regimes and land use and management systems in Northern Eurasia have the potential to disrupt the terrestrial sink of atmospheric CO2 in a way that accelerates global climate change. To determine the recent trends in the carbon balance of the arctic and boreal ecosystems of this region, we performed a retrospective analysis of terrestrial carbon dynamics a...

2013
Corey L. Pray Weston H. Nowlin Michael J. Vanni

Many freshwater ecosystems receive allochthonous resource subsidies from adjacent terrestrial environments. In eastern North American forests, geographic broods of periodical cicadas emerge every 13 to 17 y to breed, and local abundances can sometimes be .300 individuals/m. Most individuals avoid predation, senesce after breeding, and become a resource pulse for forest ecosystems; some cicada c...

Journal: :Marine environmental research 2007
Samuli Helama Bernd R Schöne Andreas J Kirchhefer Jan K Nielsen David L Rodland Ronald Janssen

Annual growth increments were examined from shells of the ocean quahog (Arctica islandica L.) from northwest Norway and from tree-ring samples of the Scots pine (Pinus sylvestris L.) from nearby coastal areas. The reconstructed annual growth increments were used to compare growth variability in marine and terrestrial ecosystems. Spatiotemporal comparison of the growth records showed statistical...

2013
Chengcheng Gang Wei Zhou Jianlong Li Yizhao Chen Shaojie Mu Jizhou Ren Jingming Chen Pavel Ya. Groisman

To assess the variation in distribution, extent, and NPP of global natural vegetation in response to climate change in the period 1911-2000 and to provide a feasible method for climate change research in regions where historical data is difficult to obtain. In this research, variations in spatiotemporal distributions of global potential natural vegetation (PNV) from 1911 to 2000 were analyzed w...

Journal: :Global change biology 2015
Yiqi Luo Trevor F Keenan Matthew Smith

Terrestrial ecosystems sequester roughly 30% of anthropogenic carbon emission. However this estimate has not been directly deduced from studies of terrestrial ecosystems themselves, but inferred from atmospheric and oceanic data. This raises a question: to what extent is the terrestrial carbon cycle intrinsically predictable? In this paper, we investigated fundamental properties of the terrestr...

Journal: :Ambio 2002
Peter M Vitousek Stephan Hättenschwiler Lydia Olander Steven Allison

Anthropogenic changes to the global N cycle are important in part because added N alters the composition, productivity, and other properties of many natural ecosystems substantially. Why does added N have such a large impact? Why is N in short supply in so many natural ecosystems? Processes that slow the cycling of N relative to other elements and processes that control ecosystem-level inputs a...

2013
Deron E. Burkepile D. E. Burkepile

‘Grazing ecosystem’ is typically used to describe terrestrial ecosystems with high densities of mammalian herbivores such as the Serengeti in East Africa or the Greater Yellowstone Ecosystem in North America. These abundant, large herbivores determine plant community dynamics and ecosystem processes. The general concepts that define grazing ecosystems also aptly describe many aquatic ecosystems...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2007
Helmut Hillebrand Daniel S Gruner Elizabeth T Borer Matthew E S Bracken Elsa E Cleland James J Elser W Stanley Harpole Jacqueline T Ngai Eric W Seabloom Jonathan B Shurin Jennifer E Smith

Consumer and resource control of diversity in plant communities have long been treated as alternative hypotheses. However, experimental and theoretical evidence suggests that herbivores and nutrient resources interactively regulate the number and relative abundance of coexisting plant species. Experiments have yielded divergent and often contradictory responses within and among ecosystems, and ...

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