Yin Xiao-Han, Hao Guang-You, Sterck Frank
Key Laboratory of Terrestrial Ecosystem Carbon Neutrality, Shengyang, Liaoning 110016, China.
CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shengyang, Liaoning 110016, China.
Tree Physiol. 2023 May 12;43(5):722-736. doi: 10.1093/treephys/tpad008.
In cold and humid temperate forests, low temperature, late frost and frequent freeze-thaw cycles are the main factors limiting tree growth and survival. Ring- and diffuse-porous tree species differing in xylem anatomy coexist in these forests, but their divergent adaptations to these factors have been poorly explored. To fill this knowledge gap, we compared four ring-porous and four diffuse-porous tree species from the same temperate forest in Northeast China by quantifying their leaf and stem functional traits, their stem growth rates using tree ring analysis and their resistance to cold represented by upper altitude species distribution borders from survey data. We found that the ring-porous trees were characterized by traits related to more rapid water transport, carbon gain and stem growth rates than those of the diffuse-porous species. Compared with the diffuse-porous species, the ring-porous species had a significantly higher shoot hydraulic conductance (Ks-shoot, 0.52 vs 1.03 kg m-1 s-1 MPa-1), leaf photosynthetic rate (An, 11.28 vs 15.83 μmol m-2 s-1), relative basal area increment (BAIr, 2.28 vs 0.72 cm year-1) and stem biomass increment (M, 0.34 vs 0.09 kg year-1 m-1). However, the observed upper elevational distribution limit of the diffuse-porous species was higher than that of the ring-porous species and was associated with higher values of conservative traits, such as longer leaf life span (R2 = 0.52). Correspondingly, BAIr and M showed significant positive correlations with acquisitive traits such as Ks-shoot (R2 = 0.77) and leaf photosynthetic rate (R2 = 0.73) across the eight species, with the ring-porous species occurring at the fast-acquisitive side of the spectrum and the diffuse-porous species located on the opposite side. The observed contrasts in functional traits between the two species groups improved our understanding of their differences in terms of growth strategies and adaptive capabilities in the cold, humid temperate forests.
在寒冷潮湿的温带森林中，低温、晚霜和频繁的冻融循环是限制树木生长和存活的主要因素。木质部解剖结构不同的环孔材和散孔材树种共存于这些森林中，但它们对这些因素的不同适应方式尚未得到充分研究。为了填补这一知识空白，我们通过量化来自中国东北同一温带森林的四种环孔材和四种散孔材树种的叶和茎功能性状、利用树木年轮分析测定其茎生长速率以及根据调查数据用海拔上限物种分布边界来表示其抗寒能力，对它们进行了比较。我们发现，与散孔材树种相比，环孔材树木具有与更快的水分运输、碳获取和茎生长速率相关的性状。与散孔材树种相比，环孔材树种的枝条水力导度（Ks-枝条，0.52对1.03 kg m-1 s-1 MPa-1）、叶片光合速率（An，11.28对15.83 μmol m-2 s-1）、相对断面积生长量（BAIr，2.28对0.72 cm 年-1）和茎生物量增量（M，0.34对0.09 kg 年-1 m-1）显著更高。然而，观察到的散孔材树种的海拔分布上限高于环孔材树种，并且与保守性状的较高值相关，例如较长的叶片寿命（R2 = 0.52）。相应地，在这八个树种中，BAIr和M与诸如Ks-枝条（R2 = 0.77）和叶片光合速率（R2 = 0.73）等获取性性状呈显著正相关，环孔材树种处于该谱的快速获取端，而散孔材树种位于相反一端。观察到的两个树种组在功能性状上的差异，增进了我们对它们在寒冷潮湿温带森林中的生长策略和适应能力差异的理解。
