German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany.
Systematic Botany and Functional Biodiversity, Institute of Biology, Leipzig University, Johannisallee 21-23, 04103, Leipzig, Germany.
Sci Rep. 2019 Dec 11;9(1):18784. doi: 10.1038/s41598-019-55256-x.
Seedlings in moist tropical forests must cope with deep shade and seasonal drought. However, the interspecific relationship between seedling performance in shade and drought remains unsettled. We quantified spatiotemporal variation in shade and drought in the seasonal moist tropical forest on Barro Colorado Island (BCI), Panama, and estimated responses of naturally regenerating seedlings as the slope of the relationship between performance and shade or drought intensity. Our performance metrics were relative height growth and first-year survival. We investigated the relationship between shade and drought responses for up to 63 species. There was an interspecific trade-off in species responses to shade versus species responses to dry season intensity; species that performed worse in the shade did not suffer during severe dry seasons and vice versa. This trade-off emerged in part from the absence of species that performed particularly well or poorly in both drought and shade. If drought stress in tropical forests increases with climate change and as solar radiation is higher during droughts, the trade-off may reinforce a shift towards species that resist drought but perform poorly in the shade by releasing them from deep shade.
在湿润的热带森林中，幼苗必须应对深荫和季节性干旱。然而，幼苗在荫蔽和干旱条件下的种间关系仍未得到解决。我们量化了巴拿马巴罗科罗拉多岛（BCI）季节性湿润热带森林中荫蔽和干旱的时空变化，并估计了自然再生幼苗的反应，方法是将性能与荫蔽或干旱强度之间的关系的斜率作为性能的度量。我们的性能指标是相对高度生长和第一年的存活率。我们研究了多达 63 个物种的荫蔽和干旱响应之间的关系。物种对荫蔽的反应与物种对旱季强度的反应之间存在种间权衡；在荫蔽条件下表现较差的物种在旱季不会遭受严重影响，反之亦然。这种权衡部分源于没有哪种物种在干旱和荫蔽条件下表现特别好或特别差。如果热带森林的干旱压力随着气候变化而增加，并且在干旱期间太阳辐射更高，那么这种权衡可能会通过将那些能够抵抗干旱但在荫蔽条件下表现不佳的物种从深荫中释放出来，从而加强向这些物种的转移。
