4 research outputs found
An Investigation into the Poor Survival of an Endangered Coho Salmon Population
To investigate reasons for the decline of an endangered population of coho salmon (O. kisutch), 190 smolts were acoustically tagged during three consecutive years and their movements and survival were estimated using the Pacific Ocean Shelf Tracking project (POST) array. Median travel times of the Thompson River coho salmon smolts to the lower Fraser River sub-array were 16, 12 and 10 days during 2004, 2005 and 2006, respectively. Few smolts were recorded on marine arrays. Freshwater survival rates of the tagged smolts during their downstream migration were 0.0–5.6% (0.0–9.0% s.e.) in 2004, 7.0% (6.2% s.e.) in 2005, and 50.9% (18.6% s.e.) in 2006. Overall smolt-to-adult return rates exhibited a similar pattern, which suggests that low freshwater survival rates of out-migrating smolts may be a primary reason for the poor conservation status of this endangered coho salmon population
Evidence-based Kernels: Fundamental Units of Behavioral Influence
This paper describes evidence-based kernels, fundamental units of behavioral influence that appear to underlie effective prevention and treatment for children, adults, and families. A kernel is a behavior–influence procedure shown through experimental analysis to affect a specific behavior and that is indivisible in the sense that removing any of its components would render it inert. Existing evidence shows that a variety of kernels can influence behavior in context, and some evidence suggests that frequent use or sufficient use of some kernels may produce longer lasting behavioral shifts. The analysis of kernels could contribute to an empirically based theory of behavioral influence, augment existing prevention or treatment efforts, facilitate the dissemination of effective prevention and treatment practices, clarify the active ingredients in existing interventions, and contribute to efficiently developing interventions that are more effective. Kernels involve one or more of the following mechanisms of behavior influence: reinforcement, altering antecedents, changing verbal relational responding, or changing physiological states directly. The paper describes 52 of these kernels, and details practical, theoretical, and research implications, including calling for a national database of kernels that influence human behavior
Nitrogen fertilization has differential effects on N allocation and lignin in two Populus species with contrasting ecology
Black cottonwood (BC, Populus trichocarpa)
and hybrid aspen (HA, P. tremula 9 tremuloides) differ in
their ecology of being adapted to wet and drier conditions
as riparian and early successional forest species, respectively.
We tested the hypothesis that these ecological differences
were reflected in higher nitrogen (N) use
efficiency in HA than in BC and that HA would allocate
more resources belowground than BC in the presence of
high and low N availability. We expected that responses of
wood properties to elevated N would be more pronounced
in the species with higher wood formation in response to N
supply. HA showed higher belowground biomass partitioning
than BC in the presence of low (0.2 mM) and high
(2 mM) N supply, but in contrast to our expectation wholeplant
nitrogen use efficiency and the stem carbon-tonitrogen
balance were lower than in BC. In response to
elevated N, HA exhibited stronger stimulation of biomass
production than BC, especially of the stem, which showed
significant increases in biomass and volume but decreases
in density. Lignification, especially the production of
guaiacyl (G)-compared to syringyl (S)-lignin, was delayed
in HA compared with BC wood. Since G lignin leads to
stronger crosslinking than S lignin, its delayed formation
may have enabled stronger expansion and higher volume
increment of HA than of BC stems. Our results suggest that
BC, a poplar species adapted to fluctuating N supply, is less
responsive to differences in N availability than aspen that
occurs in low N environments.peerReviewe