Vegetation Selection Affects Landscape Quality in Urban Environments.

Turfgrass areas have been perceived to contaminate surface and ground waters.  As resources for maintaining aesthetic landscapes diminish, municipalities in the United States have decided to replace turfgrasses with supposed lower maintenance vegetative selections without adequate information on overall effects to landscape quality.  A field study was initiated investigating the effects of multiple vegetation types on heat accumulation, leachate quantity and quality, and total water usage.  Plots consisted of metal lysimeters containing a leachate collection system and planted to St. Augustinegrass (Stenotaphrum secundatum [Walter] Kuntze), bermudagrass (Cynodon dactylon [L.] Pers.), big bluestem (Andropogon gerardii Vitman) and gulf coast muhly (Muhlenbergia capillaris [Lam.] Trin.), red oak tree (Quercus rubra L.), St. Augustinegrass plus red oak tree, or big bluestem and gulf coast muhly in combination with a red oak tree. Leachate collection included total volumes and analysis for nitrate and soluble phosphorus.  Thermocouples monitored soil temperatures every 15 minutes and six soil moisture probes within each lysimeter monitored actual evapotranspiration.  Mean leachate depths over the first year of study ranged from 40.0 to 113.1 mm.  Nitrate losses appear correlated to leachate volumes and ranged from 1.1 to 37.9 kg ha^-1.  Treatments containing St. Augustinegrass appeared to maintain lower soil temperatures during the summer months.  Urban vegetation selection impacts maximum daily temperature loading and groundwater characteristics and may be controlled to improve overall landscape sustainability.