نتایج جستجو برای: npp

تعداد نتایج: 2522  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2014
Jianwu Tang Sebastiaan Luyssaert Andrew D Richardson Werner Kutsch Ivan A Janssens

The traditional view of forest dynamics originated by Kira and Shidei [Kira T, Shidei T (1967) Jap J Ecol 17:70-87] and Odum [Odum EP (1969) Science 164(3877):262-270] suggests a decline in net primary productivity (NPP) in aging forests due to stabilized gross primary productivity (GPP) and continuously increased autotrophic respiration (Ra). The validity of these trends in GPP and Ra is, howe...

2007
Brian D. Kloeppel

T he measurement of net primary productivity (NPP) in forest ecosystems presents a variety of challenges because of the large and complex dimensions of trees and the difficulties of quantifying several components of NPP. As summarized by Clark et al. (2001a), these methodological challenges can be overcome, and more reliable spatial and temporal comparisons can be provided, only if greater conc...

2003
D. Scott Green John E. Erickson Eric L. Kruger

The net primary productivity (NPP) of a plant community is often positively and linearly related to the amount of photosynthetically active radiation absorbed by its canopy (APAR). The slope of this relationship is governed by the efficiency (ε) of APAR use in biomass production (NPP = APAR×ε). This intuitive model offers a promising means of generating large-scale NPP estimates, but its utilit...

Journal: :The Biochemical journal 2000
J M Ribeiro J López-Gómez J M Vergeles M J Costas M García-Díaz A Fernández A Flores J C Cameselle

Rat liver nucleotide pyrophosphatase/phosphodiesterase I (NPP/PDE) catalysed efficiently the transfer of adenylate from ATP to alcohols (methanol, ethanol, propanol, ethylene glycol, glycerol, 2, 2-dichloroethanol and glycerol 2-phosphate), which acted as adenylate acceptors competing with water with different efficiencies. NPP/PDE kinetics in alcohol/water mixtures were accounted for by rate e...

Journal: :Environmental management 2010
Dengsheng Lu Xiaofeng Xu Hanqin Tian Emilio Moran Maosheng Zhao Steven Running

Net primary productivity (NPP) is one of the major ecosystem products on which human societies rely heavily. However, rapid urban sprawl and its associated dense population and economic conditions have generated great pressure on natural resources, food security, and environments. It is valuable to understand how urban expansion and associated demographic and economic conditions affect ecosyste...

2009
F. Stuart Chapin Jack McFarland A. David McGuire Eugenie S. Euskirchen Roger W. Ruess Knut Kielland

1. Most current climate–carbon cycle models that include the terrestrial carbon (C) cycle are based on a model developed 40 years ago byWoodwell &Whittaker (1968) and omit advances in biogeochemical understanding since that time. Their model treats net C emissions from ecosystems as the balance between net primary production (NPP) and heterotrophic respiration (HR, i.e. primarily decomposition)...

2005
Don Garlington

The so-called New Perspective on Paul (NPP) has been likened to a Copernican revolution. Whether one is inclined to defend or assail it, the fact remains that Pauline studies will never be the same again. Some may try to ignore it, but apparently it is not going away, at least not anytime soon. And while many may wish that it would go away, it is my impression that much of the controversy that ...

2004
BEATRIZ MODENUTTI ROBERTO BERTONI

1. The photosynthetic efficiencies of the mixotrophic ciliate Ophrydium naumanni and the autotrophic dinoflagellate Gymnodinium paradoxum were investigated using laboratory and field experiments in Lake Moreno Oeste (41 5¢S and 71 33¢W, 758 m a.s.l.), in the Nahuel Huapi System (North Patagonia, Argentina). 2. The effect of different underwater light intensities on net primary production (NPP) ...

Journal: :American journal of physiology. Heart and circulatory physiology 2003
Yinghong Yu Andrew Kramer Julio Spinelli Jiang Ding Walter Hoersch Angelo Auricchio

We tested whether biventricular resynchronization explains contractile function changes with univentricular and biventricular pacing in heart failure patients with varying magnitudes of baseline biventricular asynchrony. Thirty patients (New York Hospital Association class > or = III, QRS duration > or =120 ms) were tested. Contractile function was measured by left ventricular maximum first der...

Journal: :Journal of morphology 1997
M J Myers K Steudel

For better understanding of the links between limb morphology and the metabolic cost of locomotion, we have characterized the relationships between limb length and shape and other functionally important variables in the straightened forelimbs and hindlimbs of a sample of 12 domestic dogs (Canis familiaris). Intra-animal comparisons show that forelimbs and hindlimbs are very similar (not signifi...

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