黄土丘陵区阴坡和阳坡优势木本植物叶功能性状比较

Comparison of Leaf Functional Traits of Dominant Woody Plants on Shady Slope and Sunny Slope in the Loessial Hilly Region

通过比较阴坡和阳坡优势种(阴坡:山杨、油松、辽东栎和刺槐;阳坡:荆条、山桃、狼牙刺和黄刺玫)叶功能性状(比叶质量、膨压损失点对应的叶水势、叶碳同位素组成δ13 C及叶N、P和K含量)的差异,探讨了植物对不同坡向的生存和适应机制。结果表明:(1)阳坡优势种较阴坡优势种具有高的叶δ13 C,且在旱季具有较高的K含量,表明高水分利用效率和K素累积是阳坡植物适应其生境的重要手段。(2)阳坡优势种间叶性状差异小于阴坡优势种,阳坡植物叶性状表现出明显的趋同性。(3)8种优势植物中,刺槐的比叶质量最小,叶N和P含量最高,叶δ13 C相对较高,反映了其高光合和高水分利用效率的特性,表明刺槐采取竞争性生存策略。相比之下,油松的比叶质量最大,其叶δ13 C、N、P和K含量最低,表明油松采取防御性生存策略,其他6种植物介于中间。

The differences of leaf functional traits （leaf mass per area, leaf water potential at turgor loss point, leaf carbon isotope composition δ^13 C and leaf N, P and K contents） of dominant woody plants on shady slope and sunny slope （Populus davidiana , Pinus tabulaeformis , Quercus liaotungensis and Robinia pseudoacacia growing on the shady slope, Vitex negundo, Prunus davidiana, Sorphora viciifolia and Rosa xanthina growing on the sunny slope） were compared in order to probe into the mechanism that plants adapt to differ- ent slope aspects. The results showed that： 1） the dominant species on the sunny slope had higher leaf δ^13 C and K content in the dry season, indicating that higher water use efficiency and K accumulation are the major mechanisms of plant adaptation to the habitat on the sunny slope; 2） the variation of leaf functional traits of dominant woody species growing on the sunny slope was slighter compared to those growing on the shady slope, demonstrating the convergence of leaf functional traits of dominant woody species growing on the sunny slope; 3） Robinia pseudoacacia had the least leaf mass per area, the highest N, P and K contents and relatively higher leaf δ^13 C among eight species, reflecting its high photosynthetic capacity and water use effi- ciency, and the competitive strategy to survive. On the contrary, Pinus tabulaeformis had the highest leaf mass per area, the lowest δ^13 C, N, P and K contents, suggesting that it uses the defensive strategy to survive. The survival strategies of other six species are among the competitive and defensive spectrum.