黄河三角洲刺槐人工林内空气负离子的变化特征

The Variation of Negative Air Ions of Robinia pseudoacacia Plantation in the Yellow River Delta

以黄河三角洲30年生人工刺槐纯林和混交林为研究对象,2015年3月至翌年2月对其林内空气负离子和相关气象因子进行了同步观测,以了解人工林内空气负离子浓度的变化规律。结果表明,不同模式下空气负离子(NAI)浓度呈明显的季节变化,夏季>秋季>春季>冬季;空气离子评议系数(CI)表明,夏季(1.04)空气质量最佳,秋春(0.92、0.70)次之,冬季(0.64)最低;日变化呈双峰曲线,峰值分别出现在10∶00-11∶00和16∶00左右,12∶00-14∶00左右出现谷值。不同模式人工林年均空气负离子浓度和离子评议系数大小依次为刺槐+白蜡混交林(RF)>刺槐+榆树混交林(RU)>刺槐+臭椿混交林(RA)>刺槐纯林(R),其NAI浓度和CI值分别为705个/cm^3、656个/cm^3、623个/cm^3、585个/cm^3和0.93、0.84、0.78、0.75。对空气负离子浓度与林分因子和气象因子的相关分析显示,空气负离子浓度与郁闭度呈极显著正相关(P<0.01),与胸径呈显著正相关(P<0.05),与树高和枝下高呈负相关;与林内温度呈显著正相关(P<0.05),与林内湿度、风速无显著相关性。

Taking the 30-year-old Robinia pseudoacacia plantations and mixed forests as test objects,a synchronous observation was conducted on the air negative ion concentration and related meteorological factors from March 2015 to February 2016. The concentration of air negative ion( NAI) of different afforestation mode showed a trend of obvious seasonal variation,summer>autumn>spring>winter. The coefficient of air ion( CI) showed that the air quality of summer( 1. 04) was the best,autumn( 0. 92) and spring( 0. 70) were better,and winter( 0. 64)was the last one. The curve of daily variation of concentration of negative air ions showed two single peak,and the peak value were at 10∶00-11∶00 and 16∶00,the valley value were at 12∶00 to 16∶00. The mean annual air negative ion and the coefficient of air ion( CI) of different afforestation mode were in the order of mingled forest of Robinia pseudoacacia Linn. and Fraxinus velutina Torr.( RF) >mingled forest of Robinia pseudoacacia Linn. and Ulmus pumila L.( RU) > mingled forest of Robinia pseudoacacia Linn. and Ailanthus altissima( Mill.) Swingle( RA) > Robinia pseudoacacia Linn.( R),and the NAI and CI of them were 705 ions/cm^3,656 ions/cm^3,623 ions/cm^3,585 ions/cm^3 and 0. 93,0. 84,0. 78,0. 75 respectively. The correlation analysis of air negative ion,forest factors and meteorological factors showed that the NAI had very significant positive correlation with crown density( P<0. 01),significant positive correlation with DBH( P<0. 05),and negative correlation with the height of tree and clear bole height; and the NAI had significant positive correlation with forest temperature( P <0. 05),no significant correlation with humidity and wind speed.