长白山阔叶红松林中水曲柳根呼吸及影响因素

Root respiration of Fraxinus mandushurica and its controls in broadleaf-Korean pine mixed forest of Changbai mountains

采用离体根法于2007年5-10月测定了长白山阔叶红松林组成树种水曲柳4个龄级林木的根系呼吸,监测了林内空气温度、不同深度土壤温度、土壤含水量及根系氮含量,初步研究了水曲柳天然林根系呼吸季节变化及其影响因素。结果表明:4个龄级的根系呼吸速率均具有明显的季节动态,其中7月份最高,10月份最低,呈单峰曲线,生长季节的不同月份根系呼吸速率在1.69～9.74μmol/(g·s)之间;根系呼吸速率随温度的升高和根系氮含量增加而增强,而土壤水分含量在一定范围内的增加可使根系呼吸作用强度增加,但水分过多也会对根系呼吸产生抑制作用;不同龄级的根系呼吸对温度变化的响应并不相同,其温度系数Q10值在1.54～2.89之间变化,随林龄增加而变大。

To study the seasonal variation of root respiration of Fraxinus mandushurica and its controls in broadleaf-Korean pine mixed forest of Changbai mountains, monthly root respiration rate was measured using in vitro root method from May to October 2007, and air temperature, soil temperature, soil moisture and root N content were determined simultaneously. The results showed that the root respiration rate of four age classes had an obvious seasonal variation, with the maximum occurring in July and the minimum in October. The root respiration rate ranged between 1.69 and 9.74 umol/（ g· s） during the growing season. The root respiration rate increased with increasing air temperature, soil temperature and root N content. More soil water in a certain range improved root respiration rate, but excessive water in soil, on the contrary, restrained root respiration rate. The response of the root respiration to temperature differed with age class, and the Q10 value ranged from 1.54 to 2. 89, which increased with increasing forest age.