Soil Temperature Regimes in the Lienhuachih Area of Central Taiwan

Soil temperature and its fluctuations, which affect the soil’s physical and chemical properties, biological activity, and vegetation growth, are considered to be important characteristics of soil. Historical soil temperature records of 3 observations at 09:00, 14:00, and 21:00 within a day from 1982 to 1991 in the Lienhuachih area were reorganized and analyzed to understand seasonal and daily temperature fluctuations in the study area. The results indicated that the yearly average temperatures for the air, and soil layers at 0, 5, 10, 20, and 30 cm from the soil surface were 21.4, 22.0, 22.7, 22.7, 23.1, and 22.8℃, respectively, and the maximum and minimum monthly average soil temperatures respectively occurred in July and January for air and all soil layers. The highest values of the monthly average soil temperature mostly occurred at 20-cm depth from the soil surface, which indicated that soil at this depth contained the maximum heat as a result of on energy balance from receiving and emitting solar radiation and the internal energy of the earth. Ranges of yearly temperature fluctuations were 14.3, 13.2, 13.0, 11.6, 11.1, and 10.5℃ for air and soil depths at 0, 5, 10, 20, and 30 cm below the soil surface, respectively. This indicates that the deeper the soil the smaller changes in temperature that were observed. The highest soil temperatures within a day were always the records observed at 14:00 for all depths, while the lowest were records observed at 09:00. The magnitude of daily soil temperature fluctuations exceeding 3℃ only occurred in soil layers at < 5 cm in depth. In addition, fluctuations within a day were insignificant in layers deeper than 5 cm from the soil surface in the Lienhuachih area.土壤温度及其波动会影响土壤的物理化学性质、生物活性与植被生长，被视为土壤的重要特征之一。本研究整理并分析了莲华池（Lienhuachih）区域1982至1991年间，每日09:00、14:00、21:00三个观测时刻的历史土壤温度记录，以探究研究区域的季节与昼夜温度波动规律。结果表明，空气及地表下0、5、10、20、30 cm土层的年平均温度分别为21.4℃、22.0℃、22.7℃、22.7℃、23.1℃、22.8℃；空气与所有土层的月平均最高、最低温分别出现在7月和1月。地表下20 cm土层的月平均土壤温度最高，这是由于该土层在接收与发射太阳辐射的能量平衡及地球内部热能的共同作用下，储存了最多的热量。空气及地表下0、5、10、20、30 cm土层的年温度波动范围分别为14.3℃、13.2℃、13.0℃、11.6℃、11.1℃、10.5℃，由此可见土层越深，温度变化幅度越小。所有土层的日最高温均出现在14:00，最低温则均出现在09:00。日土壤温度波动幅度超过3℃的情况仅见于地表下深度小于5 cm的土层；此外，莲华池区域地表下深度大于5 cm的土层，其昼夜温度波动极不显著。