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Abstract
The overwintering of evergreens without irrigation in plastic structures was best accomplished in a house oriented in a north-south direction and covered with milky polyethylene. Dehydration of evergreens in a structure covered with clear polyethylene and oriented in an east-west direction was attributed to high vapor pressure gradients that occurred in clear days. Evergreens overwintered in structures covered with clear polyethylene should be inspected periodically and irrigated as necessary to prevent desiccation.
Abstract
Seedlings of European birch (Betula pendula Roth.) grew rapidly (3.4 cm/week) in long days (8 hours of natural light plus 2 hours of supplemental light in the middle of the dark period). Two weeks of short days (8 hours of natural light) inhibited shoot growth and promoted the onset of dormancy. Daylength did not effect the rate of root growth. Root pruning suppressed the rate of root growth for 2 weeks, but once active tips were formed the rate of growth was similar to unpruned roots. Complete defoliation or covering of the foliage on short day dormant plants terminated root growth.
Abstract
Plants have a great impact upon the urban microclimate in contrast to dry structural materials. Infrared surface temp can be substantially modified by evaporative cooling and the interception of radiant energy by plants to reduce the heat island characteristic of the summer urban microclimate.
High temp characteristic of surfaces such as artificial turf can be reduced by irrigation. Outdoor athletic areas covered with artificial turf should be either irrigated to permit evaporative cooling or shaded to intercept solar radiant energy.
Coniferous trees appear capable of providing a small amount of attenuation for environmental noises that are either predominantly low or high frequency in composition. However, dense wide plantings are necessary to achieve effective environmental noise attenuation from vegetation alone in urban areas and the practical value of plants as an urban “sound barrier” appears questionable.