Cambial Growth Season of Brevi-Deciduous Brachystegia spiciformis Trees from South Central Africa Restricted to Less than Four Months
Cambial Growth Season of Brevi-Deciduous Brachystegia spiciformis Trees from South Central Africa Restricted to Less than Four Months
复制标题
中南部非洲落叶短柄树的形成层生长季节限制在四个月以内
作者：
V. Trouet;M. Mukelabai;A. Verheyden;H. Beeckman
我们调查形成层的生长周期在Brachystegia spiciformis，在南部非洲的季节性干燥的miombo林地的优势树种。为了更好地了解如何短落叶（经历一个短暂的，干旱引起的落叶期）这个物种的叶物候可以连接到一个独特的时期的形成层活动，我们采用了双周钉在赞比亚西部的6棵树在一年的过程中。结果表明，形成层生长的开始和结束在树木之间是同步的，但与雨季的开始和结束并不同步。相对较短（3至4个月最大）形成层生长季节对应的核心雨季，当75%的年降水量下降，并在此期间，树木处于充分的光合能力。该物种的年轮研究发现，一个显着的关系，每年的树木生长和降水量，但我们没有观察到这样的相关性在本研究中的年内分辨率。此外，形成层生长季节结束后发生的大量降雨事件并没有诱导木质部的启动或假环的形成。在解释本研究结果时应考虑低样本复制，但我们的研究结果可用于改进基于过程的陆地生态系统模型的碳分配组件，从而有助于更详细地估计miombo林地在陆地碳循环中的作用。为利用穗状短冠草树轮记录进行古气候研究提供了生理基础。
We investigate cambial growth periodicity in Brachystegia spiciformis, a dominant tree species in the seasonally dry miombo woodland of southern Africa. To better understand how the brevi-deciduous (experiencing a short, drought-induced leaf fall period) leaf phenology of this species can be linked to a distinct period of cambial activity, we applied a bi-weekly pinning to six trees in western Zambia over the course of one year. Our results show that the onset and end of cambial growth was synchronous between trees, but was not concurrent with the onset and end of the rainy season. The relatively short (three to four months maximum) cambial growth season corresponded to the core of the rainy season, when 75% of the annual precipitation fell, and to the period when the trees were at full photosynthetic capacity. Tree-ring studies of this species have found a significant relationship between annual tree growth and precipitation, but we did not observe such a correlation at intra-annual resolution in this study. Furthermore, a substantial rainfall event occurring after the end of the cambial growth season did not induce xylem initiation or false ring formation. Low sample replication should be taken into account when interpreting the results of this study, but our findings can be used to refine the carbon allocation component of process-based terrestrial ecosystem models and can thus contribute to a more detailed estimation of the role of the miombo woodland in the terrestrial carbon cycle. Furthermore, we provide a physiological foundation for the use of Brachystegia spiciformis tree-ring records in paleoclimate research.