马占相思人工林温湿效应的时空动态

TEMPORAL AND SPATIAL DYNAMICS OF TEMPERATURE AND MOISTURE IN AN ACACIA MANGIUM PLANTATION

摘要:

对马占相思人工林温湿两方面11年定位观测资料进行了总结。分析了马占相思人工林空气及土壤温湿度在空间（水平的和垂直的）和时间尺度（年、季、日）上的动态变化。从功能上来看，可把马占相思人工林的温湿效应简要地概括为调温（湿季降温、干季保温0、滞缓温变以及增温3个方面，具体体现在：①约7龄的马占相思人工林即可表现出较为明显而稳定的温湿效应。林内11年的平均气温（21.7℃）比林外低0.5℃，表层土壤（0－20 cm）的平均温度（21.3℃）比林外低2.0℃。马占相思林内极端最高温小于林外，极端最低温则高于林外。林分的降温效应湿季比干季明显，保温效应主要体现在湿季的深夜和干季气温较低的时候。②林内白天各垂直层的气温随距地高度的增加而降低，诳晚出现随高度增加气温升高的逆温现象。干季各层气温间的分异要比湿季明显。在湿季，土壤温度从地表层开始向下逐渐递减；干季0－5 cm处的地温呈递减趋势，深于5 cm则土温随浓度的增加而增加。一般林内的气温变化要滞后于林外1－2 h。③马占相思林内的平均相对湿度为82％，比林外高4％。在晴天，林内相对湿度的变化呈“U”型，林内空气湿度随高度增加而下降，但在湿季，接近林冠约7 m处的湿度要大于近地表和林冠上层。土壤湿度在0－40 cm处随土层浓度的增加而增加，40－120 cm处则随土层浓度的增加而逐渐减少。

Abstract:

Based on the data investigated from l988 to 1998 for air and soil temperature and moisture in a 15-year-old artificial forest of A cacia mangium in Guangdong, China，the temporal and spatial dynamics of the forest was analyzed． The results showed that even 7-year-old A．mangium forest was able to have function of regulating air and soil temperatures, to delay temperature variation, and to increase moisture in the forest Mean air temperature within 11 years inside forest was 21.7℃ which was 1ower than that outside forest by O.5℃．Mean soil temperature at 0—20cm depths under forest was 21.3℃ which was lower than that outside forest by 2℃, the effeet of forest on lowering temperature was more obvious in wet season than in dry season Air temperature inside forest decreased vertically with height increase at daytime，but to the contrary at night. The differences in temperature at the four vertical layers (forest height at 0.5, 2, 7 and 16 m) were more distinctive in dry season than in wet season. Air relative humidity inside forest averaged 82％ which was higher than that outside forest by 4％.