87 research outputs found
The relationship between the perception of distributed leadership in secondary schools and teachers' and teacher leaders' job satisfaction and organizational commitment
This study investigates the relation between distributed leadership, the cohesion of the leadership team, participative decision-making, context variables, and the organizational commitment and job satisfaction of teachers and teacher leaders. A questionnaire was administered to teachers and teacher leaders (n=1770) from 46 large secondary schools. Multiple regression analyses and path analyses revealed that the study variables explained significant variance in organizational commitment. The degree of explained variance for job satisfaction was considerably lower compared to organizational commitment. Most striking was that the cohesion of the leadership team and the amount of leadership support was strongly related to organizational commitment, and indirectly to job satisfaction. Decentralization of leadership functions was weakly related to organizational commitment and job satisfaction
Are Standards and Regulations of Organic Farming Moving Away from Small Farmers' Knowledge?
River Influences on Shelf Ecosystems: Introduction and Synthesis
River Influences on Shelf Ecosystems (RISE) is the first comprehensive interdisciplinary study of the rates and dynamics governing the mixing of river and coastal waters in an eastern boundary current system, as well as the effects of the resultant plume on phytoplankton standing stocks, growth and grazing rates, and community structure. The RISE Special Volume presents results deduced from four field studies and two different numerical model applications, including an ecosystem model, on the buoyant plume originating from the Columbia River. This introductory paper provides background information on variability during RISE field efforts as well as a synthesis of results, with particular attention to the questions and hypotheses that motivated this research. RISE studies have shown that the maximum mixing of Columbia River and ocean water occurs primarily near plume liftoff inside the estuary and in the near field of the plume. Most plume nitrate originates from upwelled shelf water, and plume phytoplankton species are typically the same as those found in the adjacent coastal ocean. River-supplied nitrate can help maintain the ecosystem during periods of delayed upwelling. The plume inhibits iron limitation, but nitrate limitation is observed in aging plumes. The plume also has significant effects on rates of primary productivity and growth (higher in new plume water) and microzooplankton grazing (lower in the plume near field and north of the river mouth); macrozooplankton concentration (enhanced at plume fronts); offshelf chlorophyll export; as well as the development of a chlorophyll ?shadow zone? off northern Oregon
Habitat use at fine spatial scale: how does patch clustering criteria explain the use of meadows by red deer ?
Large mammalian herbivores are keystone species
in different ecosystems. To mediate the effects of large
mammalian herbivores on ecosystems, it is crucial to understand
their habitat selection pattern. At finer scales, herbivore
patch selection depends strongly on plant community
traits and therefore its understanding is constrained by patch
definition criteria. Our aim was to assess which criteria for
patch definition best explained use of meadows by wild,
free-ranging, red deer (Cervus elaphus) in a study area in
Northeast Portugal. We used two clustering criteria types
based on floristic composition and gross forage classes, respectively.
For the floristic criteria, phytosociological approach
was used to classify plant communities, and its
objectivity evaluated with a mathematical clustering of the
floristic relevés. Cover of dominant plant species was tested
as a proxy for the phytosociological method. For the gross
forage classes, the graminoids/forbs ratio and the percentage
cover of legumes were used. For assessing deer relative use of
meadows we used faecal accumulation rates. Patches clustered
according to floristic classification better explained selection of patches by deer. Plant community classifications based on
phytosociology, or proxies of this, used for characterizing
meadow patches resulted useful to understand herbivore selection
pattern at fine scales and thus potentially suitable to
assist wildlife management decisions
Organic Agriculture and Undernourishment in Developing Countries: Main Potentials and Challenges
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River influences on shelf ecosystems: Introduction and synthesis
River Influences on Shelf Ecosystems (RISE) is the first comprehensive
interdisciplinary study of the rates and dynamics governing the mixing of river and coastal
waters in an eastern boundary current system, as well as the effects of the resultant plume
on phytoplankton standing stocks, growth and grazing rates, and community structure.
The RISE Special Volume presents results deduced from four field studies and two
different numerical model applications, including an ecosystem model, on the buoyant
plume originating from the Columbia River. This introductory paper provides background
information on variability during RISE field efforts as well as a synthesis of results, with
particular attention to the questions and hypotheses that motivated this research. RISE
studies have shown that the maximum mixing of Columbia River and ocean water occurs
primarily near plume liftoff inside the estuary and in the near field of the plume. Most
plume nitrate originates from upwelled shelf water, and plume phytoplankton species are
typically the same as those found in the adjacent coastal ocean. River-supplied nitrate
can help maintain the ecosystem during periods of delayed upwelling. The plume inhibits
iron limitation, but nitrate limitation is observed in aging plumes. The plume also has
significant effects on rates of primary productivity and growth (higher in new plume
water) and microzooplankton grazing (lower in the plume near field and north of the
river mouth); macrozooplankton concentration (enhanced at plume fronts); offshelf
chlorophyll export; as well as the development of a chlorophyll “shadow zone” off
northern Oregon.Keywords: Columbia River plume, freshwater plume, RIS
The relationship between the perception of distributed leadership in secondary schools and teachers' and teacher leaders' job satisfaction and organizational commitment
From farm management to bacteriophage therapy: strategies to reduce antibiotic use in animal agriculture
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