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间伐保留密度对杉木人工林凋落物与土壤持水特性的影响
Effects of thinning retention density on litter and soil water retention characteristics of Chinese fir plantation
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摘要: 以粤北地区11年生间伐保留密度为
1200 、1800 、2500 株/hm2的杉木人工林为研究对象,探究间伐2年后不同杉木人工林凋落物和土壤持水特性的差异以及影响因素,分析不同间伐保留密度林分的持水性能。结果表明:较高的保留密度有利于凋落物量的积累,其中2500 株/hm2杉木林的凋落物现存量和厚度相较于其他2种密度林分依次增加了7.96%~30.87%和4.90%~24.92%。在不同保留密度杉木林中,1800 株/hm2林分的土壤最大持水量和土壤有效拦蓄量最大,且显著大于1200 株/hm2林分。在3种保留密度杉木林中,1800 株/hm2林分的土壤饱和持水量和土壤毛管持水量最大,相较于其他2种保留密度林分增加了6.50%~24.95%。土壤非毛管持水量随着保留密度的增大而增大,表现为2500 株/hm2(45.50 t/hm2) >1800 株/hm2(32.21 t/hm2) >1200 株/hm2(23.76 t/hm2)。相关性分析结果显示,凋落物持水量指标与凋落物厚度和现存量、土壤pH、有机碳含量、非毛管孔隙度、非毛管持水量呈显著相关,土壤持水量指标与土壤总孔隙度、毛管孔隙度和非毛管孔隙度、土壤容重、土壤有机质含量以及郁闭度和叶面积指数显著相关。坐标综合评定法结果显示,在不同保留密度林分中,凋落物和土壤综合持水能力表现为1800 株/hm2 >2500 株/hm2 >1200 株/hm2。因此,在3种不同保留密度林分中,1800 株/hm2林分的凋落物和土壤持水能力最好。Abstract: Taking Chinese fir plantation with 11−year thinning retention density of1200 ,1800 and2500 trees·hm−2 in northern Guangdong as the research object, the differences of litter and soil water retention characteristics of different Chinese fir plantation after thinning for 2 years and the influencing factors were analyzed, and the water retention performance of stands with different thinning retention density was explored. The results show that: Higher retention density was conducive to litter accumulation, and the litter inventory and thickness of2500 ·trees/hm2 Chinese fir forest increased by 7.96%~30.87% and 4.90%~24.92% compared with the other two density stands. The soil maximum water holding capacity and effective storage capacity of1800 trees/hm2 stands were the largest in different retention densities of Chinese fir forests, and were significantly greater than1200 trees/hm2 stands. The soil saturation water holding capacity and capillary water holding capacity of1800 /hm2 stands were the largest in the 3 kinds of preserved density Chinese fir forests, which increased by 6.5% to 24.95% compared with the other 2 kinds of preserved density stands. The soil non−capillary water capacity increased with the increase of retention density, which was2500 trees·hm−2(45.50 t/hm2) >1800 ·hm−2(32.21 t/hm2) > trees/hm2(23.76 t/hm2). The results of correlation analysis showed that litter water capacity was significantly correlated with litter thickness and existing stock, soil pH value, organic carbon content, non−capillary porosity, and non−capillary water capacity. The soil moisture content is significantly correlated with total porosity, capillary porosity, and non−capillary porosity, soil bulk density, soil organic matter content, canopy density and leaf area index. The results of coordinate comprehensive evaluation showed that the comprehensive water holding capacity of litter and soil was1800 trees/hm2 >2500 trees/hm2 >1200 trees/hm2 in the stands with different retention densities. In conclusion,1800 trees/hm2 stands had the best litter and soil water retention capacity among the 3 different retention density stands.