نتایج جستجو برای: visitation
تعداد نتایج: 2007 فیلتر نتایج به سال:
Pollinator-plant relationships are found to be particularly vulnerable to land use change. Yet despite extensive research in agricultural and natural systems, less attention has focused on these interactions in neighboring urban areas and its impact on pollination services. We investigated pollinator-plant interactions in a peri-urban landscape on the outskirts of the San Francisco Bay Area, Ca...
Abundance and visitation of pollinator assemblages tend to decrease with altitude, leading to an increase in pollen limitation. Thus increased competition for pollinators may generate stronger selection on attractive traits of flowers at high elevations and cause floral adaptive evolution. Few studies have related geographically variable selection from pollinators and intraspecific floral diffe...
There is growing concern that current pollinator decline will affect the reproduction of plant species, potentially driving a decline in plant population densities. We experimentally tested whether a reduction in flower visitation caused a reduction in fertilization rate in several species, and whether any reduction in fecundity of species depends on their degree of reproductive dependence on p...
Sustainable agricultural landscapes by definition provide high magnitude and stability of ecosystem services, biodiversity and crop productivity. However, few studies have considered landscape effects on the stability of ecosystem services. We tested whether isolation from florally diverse natural and semi-natural areas reduces the spatial and temporal stability of flower-visitor richness and p...
EXECUTIVE SUMMARY Evaluating the effectiveness of maternal and child home visitation programs can be challenging. The complexity of program models, coupled with considerations of real-world program implementation, requires thoughtful and flexible evaluation strategies. Yet, meaningful evaluations of home visitation programs are not only feasible, but are essential as policymakers demand stronge...
Pollinators serve critical roles for the functioning of terrestrial ecosystems, and have an estimated annual value of over $150 billion for global agriculture. Mounting evidence from agricultural systems reveals that pollinators are declining in many regions of the world, and with a lack of information on whether pollinator communities in natural systems are following similar trends, identifyin...
Modeling pollination ecosystem services requires a spatially explicit, process-based approach because they depend on both the behavioral responses of pollinators to the amount and spatial arrangement of habitat and on the within- and between-season dynamics of pollinator populations in response to land use. We describe a novel pollinator model predicting flower visitation rates by wild central-...
Pollen limitation of plant reproduction occurs in many plant species, particularly those in fragmented habitat; however, causes of pollen limitation are often unknown. We investigated the relationship between pollen limitation and pollinator visitation in the purple coneflower, Echinacea angustifolia (Asteraceae), which grows in the extremely fragmented tall grass prairie of North America. Prev...
BACKGROUND Population ageing fosters new models of care delivery for older people that are increasingly integrated into existing care systems. In the Netherlands, a primary-care based preventive home visitation programme has been developed for potentially frail community-dwelling older people (aged ≥75 years), consisting of a comprehensive geriatric assessment during a home visit by a practice ...
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