黄土丘陵区人工刺槐林温湿度缓冲效应

Buffering Effect of Artificial Robinia pseudoacacia Forest on Temperature and Humidity in Loess Hilly Region

[目的]研究黄土丘陵区人工刺槐林对环境温湿度的缓冲效应,探究不同时间尺度林带对环境气候的缓冲特点以及森林小气候效应与环境因素之间的关系,为黄土丘陵区的群落构建和植被恢复提供参考依据。[方法]选取该区域同年建立的人工刺槐林和林外空旷地为研究对象,对气温、地表温度、土壤温度和空气相对湿度进行为期一年的连续监测,量化不同时间尺度人工刺槐林的温湿度缓冲效应。[结果]林内气温、地表温度、土壤温度和相对湿度年均值分别低于林外0.13℃,0.99℃,0.92℃和0.16%。在一天中的14:00—16:00时段,林内气温、地表温度和土壤温度分别低于林外1.08℃,4.17℃和1.88℃,相对湿度高于林外2.72%;在5:00—7:00时段,林内气温和地表温度分别高于林外0.45℃和0.58℃,相对湿度低于林外1.80%。最热月(7月)林内气温、地表温度和土壤温度分别低于林外0.76℃,2.17℃和3.29℃,相对湿度高于林外1.67%;最冷月(1月)林内气温和土壤温度分别高于林外0.28℃和0.87℃,地表温度低于林外0.20℃,相对湿度低于林外1.16%。人工刺槐林的缓冲效应随环境气候变化表现不同,当林外气温、地表温度、土壤温度分别高于16.70℃,9.89℃和1.43℃时,人工刺槐林表现为降温作用,低于该温度则表现为升温作用;温度和缓冲值之间为一元三次方程关系,随着温度升高或降低,缓冲值的绝对值增大速率加快。[结论]在人工刺槐林温湿度缓冲效应影响下,林内温湿度比林外更加稳定,形成了优于林外环境气候的独特小气候。

[Objective]The buffering effect of artificial R.pseudoacacia forest on environmental temperature and humidity in the loess hilly area was studied,and the buffering characteristics of forest belts on environmental climate at different time scales and the relationship between forest microclimate effect and environmental factors were explored,so as to provide reference for community construction and vegetation restoration in the loess hilly area.[Methods]The artificial R.pseudoacacia forest planted in the same year in this area was taken as an example,and air temperature(T a),near surface temperature(T ns),soil temperature(T s)and air relative humidity(RH)inside and outside of the forest continuously for a whole year were measured.The climate buffering effects of artificial R.pseudoacacia forests at different time scales were quantified.[Results]The annual average T a,T ns,T s and RH in the forest were lower by 0.13℃,0.99℃,0.92℃and 0.16%,respectively,than those outside of the forest.During 14:00 to 16:00 of a day,the T a,T ns and T s inside of the forest were 1.08℃,4.17℃and 1.88℃lower,respectively,than those outside of the forest,while the RH of air was 2.72%higher.During 5:00 to 7:00,the T a and T ns inside of forest were 0.45℃and 0.58℃higher than those outside of forest,respectively,and the RH was 1.80%lower than that outside of forest.The T a,T ns and T s inside of forest were lower by 0.76℃,2.17℃and 3.29℃than those outside of the forest in July,respectively,and the RH was higher by 1.67%,than that outside of the forest in July.In January,when extreme low temperature occurred,the T a and T s in the forest were 0.28℃and 0.87℃higher,T ns was 0.20℃lower than those outside the forest,respectively,and RH was 1.16%lower than that outside the forest.The buffering effect of artificial R.pseudoacacia forest varied with change of environmental climate.When the T a,T ns and T s outside the forest were higher than 16.70℃,9.89℃and 1.43℃respectively,the buffering value was positive(inside the forest was warmer than outside),while they were lower than those,the buffering value was negative.The relationship between temperature and buffering value was cubic.With the increase or decrease of temperature,the absolute value of buffering value increased at a faster rate.[Conclusion]The temperature and humidity in the forest were more stable than that those outside the forest with the buffering effect of artificial R.pseudoacacia forest,forming a unique microclimate superior to the environmental climate outside the forest.