Mechanical fragmentation of leaf litter by fine root growth contributes greatly to the early decomposition of leaf litter
Mechanical fragmentation of leaf litter by fine root growth contributes greatly to the early decomposition of leaf litter
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细根生长对落叶层的机械破碎对落叶层的早期分解有很大贡献
DOI：
10.1016/j.gecco.2021.e01456
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发表时间：
2021-04
影响因子：
4
通讯作者：
陶建平
中科院分区：
文献类型：
--
作者：
王微;胡凯;黄科;陶建平
在许多森林生态系统中，林下植物根系向凋落物层扩散，在凋落物分解的早期阶段显著加速凋落物分解和养分释放。细根对凋落叶的机械破碎作用可能是其主要原因之一，但其机制尚不清楚。为定量评价细根对凋落物分解早期机械破碎的影响，采用凋落物袋模拟试验，研究了多花黑麦草细根质量对中国中亚热带万年青阔叶林优势种四川山矾凋落物分解形态和物理特性的影响。结果表明，在凋落物分解过程中，细根的生长形式多种多样，包括叶表皮的穿透和撕裂，叶肉组织与叶脉之间的“行走或插入”。细根质量对凋落物分解过程中的质量损失有显著的正效应（F_（¼ 8）543，P < 0.01）。在170天的凋落叶孵化期内，无根和少根处理的质量剩余率显著高于多根处理。在根系较多的情况下，凋落物碎片的物理抗拉强度为0.156N/mm，显著低于根系较少和无根处理（P < 0.05）。进入凋落物层的细根数量增多，可通过改变凋落物的形态、结构和物理性质，显著促进机械破碎强度。凋落物层细根生物量与分解速率呈正相关，比根长和比根尖密度是与分解相关的两个重要指标。可见，细根进入凋落物后，通过增加根长、产生新根尖和主动调节凋落物性状，促进机械破碎强度的增加，从而提高了凋落物分解初期养分释放的利用效率。
Understory plant root proliferation into the litter layer occurs in many forest ecosystems.and dramatically accelerates litter decomposition and nutrient release in the early stages..Mechanical fragmentation of leaf litter by fine roots could be one main reason, but its.mechanism is poorly understood. To quantitatively assess the influence of fine roots on the.mechanical fragmentation of leaf litter in the early decomposition process, we examined.the effects of fine root mass of Lolium multiflorum on morphological and physical characteristics.of decomposing litters of Symplocos setchuensis, a dominant species in a midsubtropical.evergreen broad-leaved forest of China, via a litter bag simulation experiment..The results showed that there were various fine root growth forms in/on decomposing.litters, including the penetration and tearing of leaf epidermis, and the “walking or.inserting” between the mesophyll tissue and the leaf veins. Fine root mass had a significant.positive effect on the mass loss during litter decomposition (F ¼ 8.543, P < 0.01). In a.duration of 170-day leaf litter incubation, the mass remaining ration was significantly.higher in no roots treatments and fewer roots treatments than that in more roots treatments..In the case of more roots, the physical tensile strength of leaf litter fragments was.0.156 N/mm, which was significantly lower than that under the treatments with fewer.roots and no roots (P < 0.05). More fine roots penetrating the litter layer could significantly.promote the intensity of mechanical fragmentation by changing the morphology, structure,.and physical properties of the leaf litter. The fine root biomass in the litter layer was.positively correlated with the decomposition rate, and the specific root length and specific.root tip density were two important indicators related to decomposition. In conclusion,.fine roots growing into litter promoted the intensity of mechanical fragmentation by.increasing root length and producing new root tips and by actively regulating litter traits,.so as to improve the utilization efficiency of nutrient release in the early decomposition.process.
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