RELATIVE IMPORTANCE OF PHOTOSYNTHETIC TRAITS AND ALLOCATION PATTERNS AS CORRELATES OF SEEDLING SHADE TOLERANCE OF 13 TROPICAL TREES
RELATIVE IMPORTANCE OF PHOTOSYNTHETIC TRAITS AND ALLOCATION PATTERNS AS CORRELATES OF SEEDLING SHADE TOLERANCE OF 13 TROPICAL TREES
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DOI：
10.1007/bf00324232
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发表时间：
1994-08-01
期刊：
影响因子：
2.7
通讯作者：
KITAJIMA, K
中科院分区：
文献类型：
--
作者：
KITAJIMA, K
在巴罗科罗拉多岛的13个热带树种中，树苗在阴凉处的第一年死亡率高的树种，在日照(23%满光)和阴凉处[2%，红远红(R：FR)比值降低的情况下]从萌发到2个月的相对生长率(RGR)都高于耐荫树种。光照下相对生长率较高的树种，在阴凉处也有较高的相对生长率。这些种间趋势可以通过物种间形态特征和分配模式的差异来解释。在每种光照条件下，耐荫树种幼苗的根冠比低于耐荫树种，单位面积叶质量高于耐荫树种，叶面积比高于耐荫树种。相反，叶片气体交换特性或这些特性中的驯化潜力与遮荫下的幼苗死亡率没有关系。在耐荫和耐荫树种中，日照幼苗的光饱和光合作用速率、暗呼吸和光补偿点均高于远遮荫幼苗。遮荫下R/FR比值的差异不影响任何树种的气体交换、分配方式或生长速率。幼树幼苗在遮荫下的存活并不依赖于较高的净光合作用或遮荫下的生物量积累速率。相反，相对生长率较高的树种在阴凉处死亡的速度比相对生长率较低的树种快。如果生存依赖于可能增强对草食动物和病原体防御的形态特征，如密集而坚韧的叶子、发达的根系和高木材密度，则可以解释这种趋势。这些特性的高建造成本，以及这些特性所导致的低LAR，应该会导致耐荫物种在遮荫和阳光下比不耐荫物种获得更低的全株碳增量和RGR。
Among 13 tropical tree species on Barro Colorado Island, species with high seedling mortality rates during the first year in shade had higher relative growth rates (RGR) from germination to 2 months in both sun (23% full sun) and shade [2%, with and without lowered red: far red (R:FR) ratio] than shade tolerant species. Species with higher RGR in sun also had higher RGR in shade. These interspecific trends could be explained by differences in morphological traits and allocation patterns among species. Within each light regime, seedlings of shade-intolerant species had lower root: shoot ratios, higher leaf mass per unit area, and higher leaf area ratios (LAR) than shade tolerant species. In contrast, leaf gas exchange characteristics, or acclimation potential in these traits, had no relationship with seedling mortality rates in shade. In both shade tolerant and intolerant species, light saturated photosynthesis rates, dark respiration, and light compensation points were higher for sun-grown seedlings than far shade-grown seedlings. Differences in R:FR ratio in shade did not affect gas exchange, allocation patterns, or growth rates of any species. Survival of young tree seedlings in shade did not depend on higher net photosynthesis or biomass accumulation rates in shade. Rather, species with higher RGR died faster in shade than species with lower RGR. This trend could be explained if survival depends on morphological charac teristics likely to enhance defense against herbivores and pathogens, such as dense and tough leaves, a well-established root system, and high wood density. High construction costs for these traits, and low LAR as a consequence of these traits, should result in lower rates of whole-plant carbon gain and RGR for shade tolerant species than shade-intolerant species in shade as well as in sun.