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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Environmental and biological controls on water and energy exchange in Florida scrub oak and pine flatwoods ecosystems
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Environmental and biological controls on water and energy exchange in Florida scrub oak and pine flatwoods ecosystems

机译：佛罗里达州水和能源交换的环境和生物控制措施擦洗了橡树和松木扁材生态系统

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Scrub oak and pine flatwoods are two contrasting ecosystems common to the humid subtropical climate of Florida. Scrub oak forests are short in stature (<2 m) and occur on well-drained sandy soils, and pine flatwoods are much taller and occur in areas with poorly drained soils. Eddy covariance measurements were made from January 2001 to February 2003 over a scrub oak forest and from January 2002 to February 2003 over an adjacent pine flatwoods located on in central Florida, USA, and exposed to similar atmospheric conditions to evaluate how the dynamics of latent heat (λE) and sensible heat (H) exchanges are affected by environmental and biological variables. Annual evapotranspiration (Et) for the scrub oak was 737 and 713 mm in 2001 and 2002, respectively. Et was comparatively higher, 812 mm, in 2002 at the pine flatwoods due to higher soil moisture and leaf area. In both ecosystems, springtime increases in λE coincided with increasing leaf area and evaporative demand. However, H was the main energy-dissipating component in the spring due to the seasonal decrease in soil water content in the upper soil profile. In the spring, mean weekly Bowen ratio (β, i.e. H/λE) values reached 1.6 and 1.2 in the scrub oak and pine flatwoods, respectively. With the onset of the summertime rainy season, λE became the dominant energy flux and β fells to < 0.4. In both ecosystems, β was strongly controlled by the interaction between leaf area and soil moisture. The lowest values of the decoupling coefficient (Ω, 0.2 and 0.25 scrub oak and pine flatwoods, respectively) also occurred during the dry springtime period indicating that surface conductance (g s ) was the mechanism controlling energy partitioning causing high β in both ecosystems. Et increases in the spring, when water in the upper soil profile was scarce and strongly retained by soil particles, indicated that plants in both ecosystems obtained water from deeper sources. The results from this research elucidate how energy partitioning differs and is regulated in contrasting ecosystems within the Florida landscape, which is important for refining regional hydrological and climate models.
机译：磨砂栎木和松木扁木是佛罗里达湿润的亚热带气候常见的两个相反的生态系统。灌木栎林的身材矮小（<2 m），多发生在排水良好的沙土上，而松木则高得多，多发生在排水不良的地区。 2001年1月至2003年2月在灌木橡树林上进行涡流协方差测量，2002年1月至2003年2月对位于美国佛罗里达州中部的相邻松木扁平木进行涡流协方差测量，并暴露于相似的大气条件下，以评估潜热动力学如何（λE）和显热（H）交换受环境和生物变量影响。磨砂橡木的年蒸散量（Et）在2001年和2002年分别为737和713 mm。由于较高的土壤水分和叶面积，2002年在松木平板上的Et相对较高，为812 mm。在这两个生态系统中，春季λE的增加与叶片面积的增加和蒸发需求的增加相吻合。然而，由于上部土壤剖面中土壤水分的季节性减少，H是春季的主要消能成分。在春季，磨砂栎木和松木扁木的平均每周鲍恩比（β，即H /λE）值分别达到1.6和1.2。随着夏季雨季的到来，λE成为主要的能量通量，β降至<0.4。在两个生态系统中，β都受到叶面积与土壤水分之间相互作用的强烈控制。去耦系数的最小值（分别为Ω橡木和松木的Ω，0.2和0.25）也发生在干旱的春季期间，这表明表面电导（g s）是控制能量分配的机制，导致两个生态系统中的β均较高。在春季，当上部土壤剖面中的水稀少并被土壤颗粒强烈保留时，Et增加，表明这两个生态系统中的植物都从更深的来源获得了水。这项研究的结果阐明了能源分配如何不同以及如何在佛罗里达景观内不同的生态系统中得到调节，这对于完善区域水文和气候模型非常重要。

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