Mueller Erin C, Day Thomas A
School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501, USA.
Int J Biometeorol. 2005 Mar;49(4):244-55. doi: 10.1007/s00484-004-0235-1. Epub 2004 Nov 18.
We assessed how small patches of contrasting urban ground cover [mesiscape (turf), xeriscape (gravel), concrete, and asphalt] altered the microclimate and performance of adjacent oleander (Nerium oleander L.) plants in Phoenix, Arizona during fall/winter (September-February) and spring/summer (March-September). Ground-cover and oleander canopy surface temperatures, canopy air temperatures and pot soil temperatures tended to be lowest in the mesiscape and highest in the asphalt and concrete. Canopy air vapor pressure deficits were lowest in the mesiscape and highest in the asphalt plot. Rates of net photosynthesis of all oleander plants were highest in October and May, and declined through mid-summer (June-July), when rates tended to be highest in the cooler mesiscape, particularly when water was limiting. During fall/winter, oleanders in the mesiscape produced 20% less biomass, 13% less leaf area, and had 12% lower relative growth rates (R(G)) than those in the other ground covers. Lower nighttime temperatures in the mesiscape in December led to oleander frost damage. During spring/summer, oleanders in the mesiscape produced 11% more biomass, 16% more leaf area, and had 3% higher R(G) than those in the other cover types. The effects of urban ground cover on oleander performance were season-specific; while oleander growth was greatest in the mesiscape during spring/summer, it was lowest during fall/winter and these plants experienced frost damage. Because all oleander plants produced >10 times as much biomass during the spring/summer, on an annual basis oleanders in the mesiscape produced 5-11% more biomass than plants in the warmer ground covers.
我们评估了亚利桑那州凤凰城秋冬（9月至2月）和春夏（3月至9月）期间，小块对比鲜明的城市地面覆盖物[中型景观（草皮）、旱生景观（砾石）、混凝土和沥青]如何改变相邻夹竹桃（Nerium oleander L.）植株的微气候和生长表现。地面覆盖物和夹竹桃冠层表面温度、冠层气温和盆栽土壤温度在中型景观中往往最低，在沥青和混凝土中最高。冠层空气水汽压亏缺在中型景观中最低，在沥青地块中最高。所有夹竹桃植株的净光合速率在10月和5月最高，并在仲夏（6月至7月）下降，此时在较凉爽的中型景观中光合速率往往最高，尤其是在水分受限的时候。在秋冬期间，中型景观中的夹竹桃生物量减少20%，叶面积减少13%，相对生长率（R(G)）比其他地面覆盖物中的夹竹桃低12%。12月中型景观中较低的夜间温度导致夹竹桃受冻害。在春夏期间，中型景观中的夹竹桃生物量增加11%，叶面积增加16%，R(G)比其他覆盖类型中的夹竹桃高3%。城市地面覆盖物对夹竹桃生长表现的影响具有季节特异性；虽然夹竹桃在春夏期间在中型景观中生长最好，但在秋冬期间生长最差，且这些植株遭受了冻害。由于所有夹竹桃植株在春夏期间产生的生物量是其他时期的10倍以上，因此全年来看，中型景观中的夹竹桃比温暖地面覆盖物中的夹竹桃生物量多5 - 11%。
