Species-Specific Growth Responses to Climate Variations in Understory Trees of a Central African Rain Forest
Species-Specific Growth Responses to Climate Variations in Understory Trees of a Central African Rain Forest
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DOI：
10.1111/j.1744-7429.2009.00613.x
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发表时间：
2010-07-01
期刊：
影响因子：
2.1
通讯作者：
Beeckman, Hans
中科院分区：
文献类型：
--
作者：
Couralet, Camille;Sterck, Frank J.;Beeckman, Hans
树木生长与环境变量之间关系的基本知识对于理解森林动态和预测植被对气候变化的响应至关重要。生长在降雨季节性明显的热带地区的树木通常形成年轮。然而，在林下，树木的生长被认为主要受到对光照和其他资源的干扰。在刚果民主共和国的半落叶木林中，常绿树种Aidia ochroleuca、Corynanthe paniculata和Xylopia wilwerthii在林下占主导地位。我们研究了它们的木材，以确定它们是否会在气候条件变化的情况下形成年轮。不同的生长年轮被证明是一年生的，并由一个共同的外部因素触发。因此，从交叉年代的个体生长环序列中构建了物种特异性位点年表。与气候变量的相关分析表明，茎径向年生长量在雨季与降水量呈显著正相关，但在不同月份间呈显著正相关。发现Aidia在雨季早期与降水有关，而Corynanthe和Xylopia在雨季结束时与降水有关。我们的研究结果表明，树木年代学方法可以理解热带森林的气候-生长关系，不仅适用于冠层树木，也适用于常绿林下物种，因此可以说适用于整个树木群落。全球气候变化影响热带森林地区的气候季节性，这可能导致不同物种之间的不同反应，并可能随着时间的推移对森林组成产生影响。
Basic knowledge of the relationships between tree growth and environmental variables is crucial for understanding forest dynamics and predicting vegetation responses to climate variations. Trees growing in tropical areas with a clear seasonality in rainfall often form annual growth rings. In the understory, however, tree growth is supposed to be mainly affected by interference for access to light and other resources. In the semi-deciduous Mayombe forest of the Democratic Republic of Congo, the evergreen species Aidia ochroleuca, Corynanthe paniculata and Xylopia wilwerthii dominate the understory. We studied their wood to determine whether they form annual growth rings in response to changing climate conditions. Distinct growth rings were proved to be annual and triggered by a common external factor for the three species. Species-specific site chronologies were thus constructed from the cross-dated individual growth-ring series. Correlation analysis with climatic variables revealed that annual radial stem growth is positively related to precipitation during the rainy season but at different months. The growth was found to associate with precipitation during the early rainy season for Aidia but at the end of the rainy season for Corynanthe and Xylopia. Our results suggest that a dendrochronological approach allows the understanding of climate-growth relationships in tropical forests, not only for canopy trees but also for evergreen understory species and thus arguably for the whole tree community. Global climate change influences climatic seasonality in tropical forest areas, which is likely to result in differential responses across species with a possible effect on forest composition over time.