2017 ◽  
Vol 51 (1) ◽  
pp. 37-54 ◽  
Author(s):  
MJ Murdoch ◽  
MD Fairchild

The colour rendition characteristics of light sources are quantified with measures based on CIE standard observers, which are reasonable representations of population averages. However, even among people with normal colour vision, the natural range of variation in colour sensitivity means any individual may see something different than the standard observer. Modelling results quantify the effects of these inter-observer differences on colour rendition measures defined by IES TM-30-15. In general, inter-observer differences tend to be smaller for light sources with high colour fidelity values, and they are affected by spectral characteristics of different lighting technologies. The magnitude of variation in colour rendition measures, up to 5–10 units in IES TM-30-15 ( Rf, Rg), measures is compared with other sources of variability and ambiguity.


AMBIO ◽  
2021 ◽  
Author(s):  
Håkan Berglund ◽  
Timo Kuuluvainen

AbstractThe natural range of variation of ecosystems provides reference conditions for sustainable management and biodiversity conservation. We review how the understanding of natural reference conditions of boreal forests in northern Europe has changed from earlier perceptions of even-aged dynamics driven by stand-replacing disturbances towards current understanding highlighting the role of non-stand-replacing disturbances and the resultant complex forest dynamics and structures. We show how earlier views and conceptual models of forest disturbance dynamics, including the influential ASIO model, provide estimates of reference conditions that are outside the natural range of variation. Based on a research synthesis, we present a revised forest reference model incorporating the observed complexity of ecosystem dynamics and the prevalence of old forests. Finally, we outline a management model and demonstrate its use in forest ecosystem management and show how regional conservation area needs can be estimated. We conclude that attaining favourable conservation status in northern Europe’s boreal forests requires increasing emphasis on ecosystem management and conservation for old forest characteristics.


1996 ◽  
Vol 17 (2) ◽  
pp. 149-158 ◽  
Author(s):  
Theodore L. Taigen ◽  
Jennifer A. O'Brien ◽  
Kentwood D. Wells

AbstractOxygen consumption of calling male spring peepers (Pseudacris crucifer) was measured at five temperatures (7, 10, 15, 19, and 23°C) encompassing the natural range of variation encountered during the breeding season. Oxygen consumption increased as a linear function of calling rate, which in turn was a linear function of temperature. Hence, nearly all the increased cost of calling at warmer temperatures was accounted for by increases in calling rate; temperature did not appear to have any independent effect on activity metabolism. During one breeding season, ambient temperature increased throughout the season, resulting in an hourly cost of calling at the end of the season that was double the cost at the beginning. Periodic warm spells also resulted in major increases in the cost of calling.


Koedoe ◽  
1999 ◽  
Vol 42 (2) ◽  
Author(s):  
C.L. Parr ◽  
B.H. Brockett

The shift in ecological thinking, from equilibrium to non-equilibrium processes has been accompanied by a move to encourage heterogeneity rather than homogeneity in landscapes. Spatial and temporal heterogeneity is thought to be a major source of biotic diversity, and disturbances such as fire, producing heterogeneity are now recognised as being important. A patch-mosaic system of burning is based on the premise that fire pattern is a surrogate for diversity, and produces a range of patches in the landscape with unique patch characteristics and fire histories. A patch-mosaic system of burning is supported historically and empirically through field studies. However, there is a need for more research into the effects of various aspects of patch and fire variables on biotic diversity, especially in savannas where our understanding is particularly poor. Landscape-scale experiments, like those to be established in the Kruger National Park, South Africa are necessary to test different burning regimes. Challenges to patch- mosaic burning include determining the 'natural' range of variation for fire parameters, implementing random ignitions, and cost-effective fire scar mapping at the appropriate resolution. An adaptive management approach should be adopted to deal with the ignorance and uncertainties that characterise the management of savanna ecosystems. This should be applied with both modelling and monitoring as key elements in this process.


2008 ◽  
Vol 56 (9) ◽  
pp. 3057-3067 ◽  
Author(s):  
K. C. Cheng ◽  
J. Beaulieu ◽  
E. Iquira ◽  
F. J. Belzile ◽  
M. G. Fortin ◽  
...  

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