2004—2008年落叶松人工林细根生产和死亡的季节动态

2004—2008年，采用微根管(minirhizotron)技术，对落叶松人工林细根生产和死亡进行连续动态观测，同时测定了温度(大气温度和土壤10 cm温度)和水分(降雨量和土壤10 cm深处含水量)的变化，研究细根生产、死亡的动态及其与温度和水分的关系.结果表明：落叶松细根年根长生产量在0.20～0.78 mm·cm^-2，死亡量在0.26～0.72 mm·cm^-2；2004—2006年细根年根长平均生产量(0.67 mm·cm^-2)和死亡量(0.59 mm·cm^-2)均高于2007—2008年细根年根长平均生产量和死亡量(0.37和0.39 mm·cm^-2)；在生长季内（5—10月），落叶松春末至夏季(6—7月) 的细根生产量占全年产量的51%～68%，秋末(10月)仅占全年的1%～4%；而夏末(8月)和秋季(9—10月)细根死亡量占全年的59%～70%，早春(5月)占全年的1%～5%.相关分析表明，大气温度变化可以解释细根生产量66%的变异，而土壤10 cm深处温度解释24%，降雨量解释27%.细根的死亡量与土壤10 cm深处温度呈指数正相关.

Seasonal variations of fine root production and mortality in Larix gmelinii plantation in 2004-2008.

Minirhizotron approach was employed to investigate the seasonal variations of fine root production and mortality in Larix gmelinii plantation in 2004-2008. At the same time, air temperature, precipitation, and soil temperatureand moisture at 10 cm depth were recorded. The overall aim of this study was todetermine the seasonal patterns of fine root production and mortality in the plantation, and their relationships with the four environmental factors. On an annual basis, the fine root length production ranged from 0.20 to 0.78 mm·cm^-2, while the mortality varied from 0.26 to 0.72 mm·cm^-2. The mean fine root production and mortality in 2004-2006 were 0.67 mm·cm^-2 and 0.59 mm·cm^-2, respectively, being greater than the corresponding values (0.37 mm·cm^-2 and 0.39mm·cm^-2) in 2007-2008. During growth season (from May to October), the fine root production in late spring and early summer (June and July) occupied 51%-68% of total, while that in late autumn (October) only occupied 1%-4%. The root mortality in late summer (August) and autumn (September and October) ranged from 59% to 70%, butthat in early spring (May) only ranged from 1% to 5%.Correlation analysis indicated that 66% of the variation in fine root production could be explained by air temperature, and only 24% and 27% could be explained by the soil temperature at 10 cm depth and precipitation, respectively. Fine root mortality only showed an exponential positive correlation with the soil temperature at 10 cm depth.