Kull Olevi, Tulva Ingmar, Vapaavuori Elina
Institute of Botany and Ecology, University of Tartu, Lai 40, 51005 Tartu, Estonia.
Ann Bot. 2003 Apr;91(5):559-69. doi: 10.1093/aob/mcg052.
Elevated CO(2) and ozone effects were studied singly and in combination on the crown structure of two Betula pendula clones. Measurements were made at the end of the second fumigation period in an open-top-chamber experiment with 9-year-old trees. Shoot ramification (number of long and short daughter shoots), shoot length, and number of metamers, leaves and buds were measured at four positions in every tree. As a result of increased temperature, trees in chambers had longer shoots and more frequent shoot ramification than control trees not enclosed in chambers. Ozone treatment decreased shoot ramification significantly. Additionally, ozone treatment resulted in an increased number of metamers in one clone. There was no statistically significant interaction between ozone effect and crown position; however, there was a slight tendency for the lower crown to be more affected by ozone. Elevated CO(2) caused a significant increase in the number of long-shoot metamers. Therefore, 2x ambient CO(2) concentration partly ameliorated the negative effect of ozone because the increased number of leaves per shoot counteracted the decreased branching. Although the main effects of elevated ozone and CO(2) were similar in the two clones, slight, statistically insignificant, differences appeared in their responses when interactions with crown position were considered.
分别研究了高浓度二氧化碳（CO₂）和臭氧对两个垂枝桦无性系树冠结构的影响，并研究了二者的联合作用。在一个开顶式气室试验中，对9年生树木在第二个熏蒸期结束时进行了测量。在每棵树的四个位置测量了枝条分枝情况（长、短侧枝数量）、枝条长度、节数、叶片数和芽数。由于温度升高，气室内的树木比未置于气室内的对照树木枝条更长，枝条分枝更频繁。臭氧处理显著降低了枝条分枝。此外，臭氧处理导致一个无性系的节数增加。臭氧效应与树冠位置之间没有统计学上的显著相互作用；然而，树冠下部受臭氧影响的趋势略有增加。高浓度CO₂导致长枝节数显著增加。因此，两倍于环境浓度的CO₂部分缓解了臭氧的负面影响，因为每个枝条上叶片数量的增加抵消了分枝的减少。尽管在两个无性系中，高浓度臭氧和CO₂的主要影响相似，但在考虑与树冠位置的相互作用时，它们的反应出现了轻微的、无统计学意义的差异。
