Castro-Díez Pilar, Navarro Javier, Pintado Ana, Sancho Leopoldo G, Maestro Melchor
Departamento Interuniversitario de Ecología, Sección de Alcalá, Facultad de Ciencias, Universidad de Alcalá. E28871 Alcalá de Henares, Madrid, Spain.
Tree Physiol. 2006 Mar;26(3):389-400. doi: 10.1093/treephys/26.3.389.
Shade and irrigation are frequently used to increase the success of Mediterranean Quercus spp. plantations. However, there is controversy about the combined effects of these treatments on plant performance. We assessed the effects of two irradiances (full sunlight and moderate shade) and two summer watering regimes (high (daily) and low (alternate days)) on leaf and whole-plant traits of 1-year-old seedlings of Quercus coccifera, Q. ilex subsp. ballota and Q. faginea grown outdoors for 8.5 months. Leaf traits included measures of morphology, nitrogen concentration, gas exchange and photochemical efficiency, and measures of whole-plant traits included biomass allocation patterns, growth phenology, across-summer leaf area change and relative growth rate (RGR). Moderate shade reduced leaf mass per area, increased photochemical efficiency, maximum carbon assimilation rate (Amax) and allocation to leaves, and prolonged the growing period in one or more of the species. Daily watering in summer increased Amax of Q. ilex and prolonged the growing period of Q. ilex and Q. faginea. Both treatments tended to increase RGR. The effect of shade was greater in the low-watering regime than in the high-watering regime for two of the 15 studied traits, with treatment effects being independent for the remaining 13 traits. Leaf nitrogen and the ability to maintain leaf area after the arid period, rather than biomass allocation traits, explained the variation in seedling RGR. Trait responsiveness to the treatments was low and similar among species and between study scales, being unexpectedly low in Q. faginea leaves. This may be because selective pressures on leaf plasticity act differently in deciduous and evergreen species. We conclude that moderate shade and daily summer watering enhance the performance of Mediterranean Quercus seedlings through species-specific mechanisms.
遮荫和灌溉经常被用于提高地中海栎属植物人工林的成活率。然而，这些处理措施对植物生长的综合影响存在争议。我们评估了两种光照强度（全日照和适度遮荫）以及两种夏季浇水方式（高频率（每日）和低频率（隔日））对生长在户外8.5个月的1年生胭脂虫栎、冬青栎亚种巴洛塔栎和欧洲水青冈栎幼苗叶片及整株植物性状的影响。叶片性状包括形态指标、氮浓度、气体交换和光化学效率，整株植物性状指标包括生物量分配模式、生长物候、整个夏季的叶面积变化和相对生长速率（RGR）。适度遮荫降低了单位面积叶质量，提高了光化学效率、最大碳同化率（Amax）以及对叶片的分配比例，并延长了一个或多个物种的生长期。夏季每日浇水提高了冬青栎的Amax，并延长了冬青栎和欧洲水青冈栎的生长期。两种处理措施都倾向于提高相对生长速率。在15个研究性状中的2个性状上，低浇水处理方式下遮荫的效果比高浇水处理方式下的效果更显著，其余13个性状的处理效果相互独立。叶片氮含量以及干旱期后维持叶面积的能力，而非生物量分配性状，解释了幼苗相对生长速率的变化。各物种间以及不同研究尺度下，性状对处理措施的响应程度较低且相似，欧洲水青冈栎叶片的响应程度出乎意料地低。这可能是因为落叶和常绿物种中，叶片可塑性所面临的选择压力作用方式不同。我们得出结论，适度遮荫和夏季每日浇水通过特定物种机制提高了地中海栎属幼苗的生长表现。
