Between-branch nitrogen competition is expected to be important during spring in temperate deciduous trees as nitrogen allocation would be higher in branches from earlier budburst than in those from later budburst. Such phenology-induced branch interaction would influence plant photosynthesis, but this has not been evaluated. Warming experiments were conducted on whole crowns (warmed trees; trunks and all branches of the same tree were warmed) or parts of the crowns (warmed branches with unwarmed control branches in the same tree), with unwarmed control trees, in saplings of the deciduous species Fraxinus lanuginosa. Spring leaf phenology and leaf photosynthetic traits were investigated to determine how the difference in temperature affects leaf phenology and photosynthetic traits. The timing of budburst was influenced by temperature—budburst was earlier in warmed trees and warmed branches than in control trees and control branches, but budburst timing did not differ between control trees and control branches or between warmed trees and warmed branches. In contrast, leaf traits were affected by the variation in phenology within crowns—nitrogen content and photosynthetic capacity were greater in the leaves of the warmed branches than in the control branches, but they did not differ between the leaves of warmed trees and control trees. Thus, branch warming altered the distribution of nitrogen between warmed and unwarmed branches as warmed branches developed faster, resulting in intracrown variation in leaf photosynthetic traits.

在春季，在温带落叶树中，分支之间的氮竞争预计将很重要，因为较早芽的分支中的氮分配将高于较早芽的分支中的氮分配。这种物候诱导的分支相互作用将影响植物的光合作用，但尚未对此进行评估。对整个树冠（温暖的树；树干和同一棵树的所有分支都进行了加热）或树冠的一部分（温暖的分支，其中未受控制的树枝在同一棵树中）进行了变暖实验，在落叶树的幼树中进行了加热物种Fraxinus lanuginosa。研究了春季叶片物候和叶片光合特性，以确定温度的差异如何影响叶片物候和光合特性。发芽的时机受温度的影响-暖树和暖枝中的爆发时间比对照树和对照枝中的早，但是在对照树和对照枝之间，或在暖树和暖枝之间，芽发时机没有差异。相反，叶片性状受树冠内部物候变化的影响-暖枝叶片的氮含量和光合能力大于对照枝，但在暖树和对照树的叶片之间氮含量和光合能力没有差异。因此，