Growth and photosynthetic response to light and nutrients of Flindersia brayleyana F. Muell., a rainforest tree with broad tolerance to sun and shade.
Growth and photosynthetic response to light and nutrients of Flindersia brayleyana F. Muell., a rainforest tree with broad tolerance to sun and shade.
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DOI：
10.1071/pp9880299
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
W. Thompson;G. Stocker;P. Kriedemann
中科院分区：
文献类型：
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作者：
W. Thompson;G. Stocker;P. Kriedemann
在北昆士兰赫伯顿山脉成熟森林中的干扰间隙中，播种了四种雨林树木的种子，这些树木的生长和发育对阳光的需求差异很大。对金合欢、澳大利亚香椿、Flindersia brayleyana 和 Darlingia darlingiana（根据从全日照到深荫的适应程度进行排序的物种）幼苗持久性和比较生长的观察证实，Flindersia 在所有条件下，从宽间隙到窄间隙（最低 0.6% 全日照当量），对阳光具有广泛的耐受性。随后，通过单叶气体交换以及对树苗的氮、磷和叶绿素的叶面分析推断出构成如此广泛耐受性的光合属性，这些树苗在两种养分×三种辐照度水平下保持180天，调整为代表森林地面（低）、树冠中部（中）和挺出树冠（高辐照度处理）的自然辐照度。事实证明，中等辐照度加上高营养物质对于空气中的叶子扩张、叶绿素含量和光合作用是最佳的。低辐照度下生长的特点是叶片栅栏组织变薄，暗呼吸率降低，单位氮叶绿素含量增加，光合作用的光补偿点降低。尽管具有这些其他遮荫叶属性，此类叶子仍保留相对较高的光合作用能力。事实证明，高辐照度加上低营养物质对于叶片扩张和光合活性的表达来说是超优的。由于表观量子产率降低，而基于氮的光合作用过程显着受损，因此慢性光抑制似乎盛行。根据叶片叶绿素含量推断的氮利用效率、光饱和CO2同化率、电子传输率和基于氮的羧化率随着生长辐照度的增加而下降。讨论了这些雨林树种在干扰间隙中建立和生长的一些生态影响。
Seed from four species of rainforest trees with widely contrasting sunlight requirements for growth and development were sown within disturbance gaps amidst mature forest on the Herberton Range in North Queensland. Observations on seedling persistence plus comparative growth of young trees of Acacia aulacocarpa, Toona australis, Flindersia brayleyana and Darlingia darlingiana (species ranked according to adaptation from full sun to deep shade) confirmed a broad tolerance of Flindersia to sunlight under all conditions, from wide to narrow gaps (minimum 0.6% full sun equivalent). Photosynthetic attributes which underlie such broad tolerance were subsequently inferred from single leaf gas exchange, plus foliar analyses of nitrogen, phosphorus and chlorophyll on tree seedlings held for 180 days under two nutrient × three irradiance levels adjusted to represent natural irradiance incident upon the forest floor (low), mid-canopy (medium) and emergent crowns (high irradiance treatment). Medium irradiance plus high nutrients proved optimal for leaf expansion, chlorophyll content and photosynthesis in air. Growth under low irradiance was characterised by thinner leaf palisade tissue, lower rates of dark respiration, increased leaf chlorophyll per unit nitrogen and lower light compensation point for photosynthesis. Such leaves retained a relatively high photosynthetic capacity despite these other shade-leaf attributes. High irradiance plus low nutrients proved supraoptimal for leaf expansion and expression of photosynthetic activity. Chronic photoinhibition appeared to prevail because apparent quantum yield was reduced, while photosynthetic processes on a nitrogen basis were substantially impaired. Nitrogen use efficiency, as inferred from leaf chlorophyll content, light saturated CO2 assimilation rate, electron transport rate and carboxylation rate on a nitrogen basis declined with increasing growth irradiance. Some ecological implications for the establishment and growth of these rainforest tree species in disturbance gaps are discussed.