Herbivory is one of the most globally distributed disturbances affecting carbon (C)-cycling in trees, yet our understanding of how it alters tree C-allocation to different functions such as storage, growth or rhizodeposition is still limited. Prioritized C-allocation to storage replenishment vs growth could explain the fast recovery of C-storage pools frequently observed in growth-reduced defoliated trees. We performed continuous 13C-labeling coupled to clipping to quantify the effects of simulated browsing on the growth, leaf morphology and relative allocation of stored vs recently assimilated C to the growth (bulk biomass) and non-structural carbohydrate (NSC) stores (soluble sugars and starch) of the different organs of two tree species: diffuse-porous (Betula pubescens Ehrh.) and ring-porous (Quercus petraea [Matt.] Liebl.). Carbon-transfers from plants to bulk and rhizosphere soil were also evaluated. Clipped birch and oak trees shifted their C-allocation patterns above-ground as a means to recover from defoliation. However, such increased allocation to current-year stems and leaves did not entail reductions in the allocation to the rhizosphere, which remained unchanged between clipped and control trees of both species. Betula pubescens and Q. petraea showed differences in their vulnerability and recovery strategies to clipping, the ring-porous species being less affected in terms of growth and architecture by clipping than the diffuse-porous. These contrasting patterns could be partly explained by differences in their C cycling after clipping. Defoliated oaks showed a faster recovery of their canopy biomass, which was supported by increased allocation of new C, but associated with large decreases in their fine root biomass. Following clipping, both species recovered NSC pools to a larger extent than growth, but the allocation of 13C-labeled photo-assimilates into storage compounds was not increased as compared with controls. Despite their different response to clipping, our results indicate no preventative allocation into storage occurred during the first year after clipping in either of the species.

中文翻译：

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在修剪的桦树和橡木树苗中，碳的储存比生长没有优惠。

食草是影响树木碳（C）循环的最广泛分布的干扰之一，但是我们对它如何将树木C分配改变为不同功能（例如存储，生长或根状茎沉积）的理解仍然有限。优先将C分配分配给存储补给与生长可以解释经常在生长减少的落叶树中观察到的C存储池的快速恢复。我们进行了连续的13C标记和剪裁，以量化模拟浏览对生长（叶片生物量）和非结构化碳水化合物（NSC）存储（可溶性糖）的生长，叶片形态以及相对于最近吸收的C的相对分配的影响。和淀粉）两种树种的不同器官：散孔性（Betula pubescens Ehrh。）和环孔性（Quercus petraea [Matt。] Liebl。）。还评估了从植物到块状土壤和根际土壤的碳转移。修剪过的桦树和橡树将其C分配模式从地面上移开，作为从落叶中恢复的一种方法。但是，对当年茎和叶的这种增加分配并不意味着对根际的分配减少，这在两种树的修剪树和对照树之间均保持不变。毛白桦和Q. petraea在剪草的脆弱性和恢复策略上表现出差异，通过打剪，环状多孔物种在生长和结构方面的影响要小于散在多孔的物种。这些对比模式可以部分地通过削波后的C循环差异来解释。落叶橡木显示出冠层生物量的恢复更快，这得益于新C的分配增加，但与它们细根生物量的大量减少有关。修剪后，两个物种恢复的NSC库都比生长恢复的程度大，但是与对照相比，13C标记的光同化物在存储化合物中的分配没有增加。尽管它们对修剪的反应不同，但我们的结果表明，在修剪任何一个物种后的第一年，都没有预防性分配到存储中。