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Synopsis: Agricultural intensification and expansion are major present and future causes of global ecosystem disruption. Natural and semi-natural reserve areas in agroecosystems are thought to be important for preservation of essential ecosystem services such as pollination, but data about land use patterns and pollinator abundance are lacking. We assessed wild bee populations in canola fields in an agriculturally intense area where virtually all land was either tilled agricultural fields or semi-natural grazed pasturelands, with the expectation that mosaics of land use types may better support ecosystem services than homogenous crop areas. Fields were chosen in two categories, five with little or no pastureland...
Conclusions:Loss of wetland cover over a 40 year period resulted in increased peak flows, increased sediment, phosphorus and nitrogen flows, and decreased waterfowl populations.Thresholds/Learnings:
Conclusions:Chemical concentrations, turbidity, changes in microclimate, and sediment production were affected to varying degrees by forest harvesting. No significant differences were found between pre-harvest and post-harvest concentrations except for calcium which was 5 times higher and sodium which was 20 times higher in the harvested watersheds. Concentrations declined over the 3 year post-harvest span.Turbidity and suspended sediment increased with road construction but declined rapidly to nearly background levels after 2 years. Air temperature increased after harvesting in all of the smaller watersheds but stream temperature was not affected.Thresholds/Learnings:
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Synopsis: Researchers analyzed variation in crop pollination services provided by native, unmanaged, bee communities on organic and conventional farms situated along a gradient of isolation from natural habitat. Pollination services from native bees were significantly, positively related to the proportion of upland natural habitat in the vicinity of farm sites, but not to any other factor studied, including farm type, insecticide usage, field size and honeybee abundance. The scale of this relationship matched bee foraging ranges. Stability and predictability of pollination services also increased with increasing natural habitat area. This strong relationship between natural habitat area and pollination services...
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Synopsis: The individual species and aggregate community contributions of native bees to crop pollination are documented, on farms that varied both in their proximity to natural habitat and management type (organic versus conventional). On organic farms near natural habitat, we found that native bee communities could provide full pollination services even for a crop with heavy pollination requirements (e.g., watermelon, Citrullus lanatus), without the intervention of managed honey bees. Agricultural intensification diminished these pollination services by roughly 3- to 6-fold. The decline of native bee pollination services with agricultural intensification resulted in significant reductions in both diversity and...
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Synopsis: Natural habitats are considered inherently indispensable to the global economy by conservationists, but few natural ecosystems afford direct and quantifiable economic benefits. Quantification of natural land value can provide compelling evidence favoring preservation over development. Wild bees are important pollinators of many crop plants, and natural patches in agroecosystems enhance pollinator services and crop yield. Bee abundance was greatest in canola fields that had more uncultivated land within 750 m of field edges and seed set was greater in fields with higher bee abundance. A cost–benefit model that estimates profit in canola agroecosystems with different proportions of uncultivated land is presented....
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Synopsis: Wildfires can negatively affect water quality by altering watershed hydrology and increasing sediment and nutrient delivery to surface waters. The Angora Fire (summer of 2007) was the largest and most severe wildfire in recent history within the Lake Tahoe basin of the Sierra Nevada. The fire burned 839 ha within the watershed (56% of the total watershed area), with 22% of the watershed affected by a high severity burn. To determine the watershed response to fire and assess the potential for downstream impacts of nutrient and sediment delivery to Lake Tahoe, the post-fire hydrology and stream water chemistry was monitored for 2 years at four locations along the length of Angora Creek, a perennial stream...
Conclusions:Concentrations of refractory compounds (tannins and lignins) increased by a factor of about 4 after clear-cutting and persisted at the higher concentration for several years. Humic substances also increased but the effect only lasted about 2 years.Thresholds/Learnings:
    map background search result map search result map Water quality response to the Angora Fire, Lake Tahoe, California Crop pollination from native bees at risk from agricultural intensification The area requirements for an ecosystem serivce: crop pollination by native bee communities in California Pollinators provide economic incentive to preserve natural land in agroecosystems Can pastureland increase wild bee abundance in agriculturally intense areas? Water quality response to the Angora Fire, Lake Tahoe, California Can pastureland increase wild bee abundance in agriculturally intense areas? Crop pollination from native bees at risk from agricultural intensification The area requirements for an ecosystem serivce: crop pollination by native bee communities in California Pollinators provide economic incentive to preserve natural land in agroecosystems