Chris Bergweiler

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Ground-level ozone continues to be a cause for concern in terrestrial ecosystems in the northeastern United States and Canada. Spreading dogbane (Apocynum androsaemifolium L.) is one of many indigenous herbaceous plant species exhibiting foliar injury that are commonly monitored in ecosystem assessment programs. Details about possible effects of ambient(More)
Stomatal conductance and net photosynthesis of common milkweed (Asclepias syriaca L.) plants in two different soil moisture regimes were directly quantified and subsequently modeled over an entire growing season. Direct measurements captured the dynamic response of stomatal conductance to changing environmental conditions throughout the day, as well as(More)
Females of the apple maggot fly,Rhagoletis pomonella, were allowed for 3 days to alight upon and oviposit in green or red 18- to 20-mm hawthorn host fruit (Crategus mollis) or green or red 45- to 55-mm apple host fruit (Malus pumila) hung from branches of potted host trees in field enclosures. Subsequently, when females were released individually on potted(More)
In Argentina no historical or present programs exist specifically assessing ecosystem health with respect to photochemical air pollution, although phytotoxic concentrations of near-ground ozone have been documented in recent years. Here we report our preliminary findings on field observations of ozone-like injury found in natural plant populations and(More)
Open-top chambers (OTCs) and corresponding ambient air plots (AA) were used to assess the impact of ambient ozone on growth of newly planted apple trees at the Montague Field research center in Amherst, MA. Two-year-old apple trees (Malus domestica Borkh 'Rogers Red McIntosh') were planted in the ground in circular plots. Four of the plots were enclosed(More)
Ambient ozone (O(3)) was measured in two Class I wilderness areas, one within the White Mountain National Forest in north central New Hampshire (NH) and one within the Green Mountain National Forest in southwestern Vermont (VT), for six weeks between 5 July and 16 August 1994, using Ogawa passive nitrite-coated filter samplers and a one week exposure period(More)
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