【摘要】 基于连续1年的兴安落叶松树干液流密度和环境因子(光照、空气温度、空气湿度、土壤温度和土壤湿度)的测定结果,探讨不同时间尺度下树干液流密度与环境因子的关系差异。在月时间尺度上,土壤温度和土壤湿度显著影响树干液流密度变化,土壤温度单位增加引起树干液流上升0.084～0.123L·cm-2month-1;在天时间尺度上,显著影响因子有土壤温度、光照和空气温度,其中土壤温度为最主要的影响因子,单位增加会导致树干液流上升1.9～2.7mL·cm-2d-1;在小时时间尺度上,主要影响因子在不同季节不同,但最主要因子多是直接影响地上叶片生理指标如光照和空气湿度,二者单位上升平均分别引起树干液流上升1.239mL·cm-2min-1和下降0.0566mL·cm-2min-1。随尺度由大到小,对树干液流影响最大的因子有从地下直接与根系水分吸收相关的土壤环境因子向地上直接影响叶片蒸腾的环境因子(光照和空气湿度)转变的趋势。同时,随着尺度增大,与树干液流显著相关的环境因子数明显下降,且相关系数R2显著提高,长期监测树木耗水可以采用监测环境因子反推的方法,而在小尺度上相同方法可能导致很大误差,最好采用直接测定法。更多还原

【Abstract】 Base on data of one-year continuous measurements of stem sap flow density for Larix gmelinii by a TDP method and environmental factors of solar radiation, air temperature, soil temperature, air humidity and soil humidity, variations in the relations between the sap flow and environmental factors were investigated at different temporal scales(month, day and hour) paper. Stepwise regression analysis showed the major environmental factors influencing the stem sap flow were different under the different temporal scales. At the temporal scale of a month, soil temperature and soil moisture markedly affected stem sap flow density and one unit increase in soil temperature could induce an increase of 0.084-0.123 L·cm-2 month-1. At the temporal scale of a day, soil temperature, solar radiation and air temperature markedly affected stem sap flow, and a unit increase of of soil temperature the most significant factor among the three, could induce an increase of 1.9-2.7 mL·cm-2 d-1 in sap flow. As temporal scale become smaller to an hour, general high impacts were from solar radiation and air humidity although much complex patterns were found according to different season. On average, one unit increase in the two parameters could induce an increase of 1.239 mL·cm-2 min-1 and a decline of 0.056 6 mL·cm-2 min-1 in stem sap flow, respectively. With time scale from large to small, in general, factors most affecting stem sap flow changed from below-ground root-water-absorption related parameters of soil temperature and moisture to above-ground leaf transpiration related parameters of light and air humidity. Moreover, much less parameters (2) with higher R2 (>89%) were found in the regression analysis at the large scale of month, while more parameters(≥4) with low R2(<0.76) were found at the small scale of hour. In the calculations of total tree or forests water consumption, accordingly, long-term monitoring of small amount of environmental parameters can be used to scaling-up with high precision, while such type of method may give large bias for short-term studies comparing with direct TDP method. Our findings would benefit the understanding stem sap flow features and its scale-up.更多还原