Root-shoot relationships of Fraxinus mandchurica

In this paper, root-shoot relationships of seedlings of Manchurican ash (Fraxinus mandchurica) in pots is studied in green house. The results show that roots and shoots have the co-ordination of growth and roots and shoots of ash have the same growth dynamics. There are very close relationships between toall root mass and total shoot mass, between fine root mass and leaf mass in this experiments. At the end growing season, ash root-shoot mass ratio and fine root-leaf mass ratio are 1 .85 and 2.01 respectively. These ratios are difference during growth season. There are larger roots than shoots on seedling stage. Low nitrogen and phosphorus produce higher root-shoot ratio, and high nutrient concentrations decrease the ratios.

磷胁迫对水曲柳幼苗叶绿素合成、光合作用和生物量分配格局的影响

采用沙培试验对水曲柳幼苗磷胁迫与叶绿素合成、光合作用和生物量分配的关系进行了研究 .结果表明 ,在磷胁迫下 ,水曲柳幼苗叶片内 5 氨基乙酰丙酸 (ALA)合成速率和胆色素原 (PBG)合成酶活性下降 ,但叶片中叶绿素a、叶绿素b、总叶绿素以及类胡萝卜素含量没有显著变化 ;水曲柳幼苗叶片和根中N浓度下降 ,P在各个部位的浓度也相应减少 ,表明N和P在苗木生理过程中具有协同作用 .叶片中N浓度下降引起光系统Ⅱ (PSⅡ )最大光量子效率 (Fv/Fm)、PSⅡ的光化学效率 (ΦPSⅡ)、电子传递速率 (ETR)以及最大光合速率 (Amax)下降 .磷胁迫对叶绿素合成的影响与Amax下降无关 .在磷胁迫下 ,水曲柳幼苗总生物量下降 ,且生物量分配倾向于地下部分 ,而在P充足或过剩条件下 。

水曲柳人工纯林及针阔混交林枯落物储量和持水特性

对帽儿山实验林场4种林分类型(水曲柳纯林、水曲柳落叶松混交林、水曲柳红松混交林、水曲柳云杉混交林)的林下枯落物储量和持水性能进行了研究。结果表明:水曲柳红松混交林的枯落物储量最大(11.2 t/hm2),其后依次为水曲柳纯林(9.7 t/hm2)、水曲柳落叶松混交林(9.3 t/hm2)、水曲柳云杉混交林(7.6 t/hm2);4种林分的枯落物最大持水量依次是水曲柳纯林(21.7 mm)、水曲柳红松混交林(21.6 mm)、水曲柳云杉混交林(16.4 mm)、水曲柳落叶松混交林(16.1 mm)。总体来看,水曲柳纯林和水曲柳红松混交林枯落物持水能力好于水曲柳云杉混交林和水曲柳落叶松混交林。