Extrait de : Vu, n°170, p. 882-884
Résumé : Article et photographies 3 p.
Siècle(s) traité(s) : 20
Droits : Domaine public
Provenance : ORkidé|Fonds privé Pierre Rostan
Permalien : http://www.manioc.org/patrimon/ORK12159
ORK12159

Éditeur(s) : HAL CCSD American Association for the Advancement of Science
Résumé : The biodiversity-productivity relationship (BPR) is foundational to our understanding of the global extinction crisis and its impacts on ecosystem functioning. Understanding BPR is critical for the accurate valuation and effective conservation of biodiversity. Using ground-sourced data from 777,126 permanent plots, spanning 44 countries and most terrestrial biomes, we reveal a globally consistent positive concave-down BPR, showing that continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The value of biodiversity in maintaining commercial forest productivity alone-US$166 billion to 490 billion per year according to our estimation-is more than twice what it would cost to implement effective global conservation. This highlights the need for a worldwide reassessment of biodiversity values, forest management strategies, and conservation priorities.
ISSN: 0036-8075

hal-01607784
https://hal.archives-ouvertes.fr/hal-01607784
DOI : 10.1126/science.aaf8957
PRODINRA : 389856

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This study compared the conventional parameters of anaerobic cycling power in physically active non-cyclists using the Pro-Race® system and a traditional chainring. The force--velocity test was chosen for this purpose because it is the shortest validated cycling laboratory test in which each parameter of maximal anaerobic power can be estimated. The power output (Wmax) and the force at whichWmax is produced (Fopt) were significantly improved with the eccentric chainring (1100±227W versus 1006±197W and 1.39±0.15 N/kg body mass versus 1.13±0.16 N/kg body mass with the eccentric and round designs, respectively; P < 0.006 and P < 0.0004, respectively). The power gained (delta power) was significantly correlated with the eccentric chainring Fopt (r = 0.649; P < 0.05), the mid-thigh circumference (r = 0.685; P < 0.05), the estimated lean thigh volume (r = 0.765; P < 0.01) and the estimated lean lower limb volume (r = 0.665; P < 0.05). We concluded that the eccentric chainring significantly improved the estimated anaerobic power output during a force--velocity test by increasing the force component, Fopt. Cautious interpretation of our results suggests that the subjects with physical attributes that contribute to developing high forces may have a significant advantage in performing with the eccentric chainring.
ISSN: 1440-2440

hal-00703458
https://hal.univ-antilles.fr/hal-00703458
DOI : 10.1016/j.jsams.2007.06.004

Résumé : 3° éd.
Siècle(s) traité(s) : 18
Provenance : Archives départementales de Guadeloupe
Permalien : http://www.manioc.org/patrimon/ADG18242
ADG18242