Institute for Forest Resources and Environment Research Center of Guizhou Province, Plateau Mountain Forest Cultivation Key Laboratory of Guizhou Province, College of Forestry, Guizhou University, Guiyang 550025, China; Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2E3, Canada.
Institute for Forest Resources and Environment Research Center of Guizhou Province, Plateau Mountain Forest Cultivation Key Laboratory of Guizhou Province, College of Forestry, Guizhou University, Guiyang 550025, China.
Sci Total Environ. 2022 Sep 10;838(Pt 3):156143. doi: 10.1016/j.scitotenv.2022.156143. Epub 2022 May 21.
Planting broadleaf trees in coniferous forests has been shown to promote biogeochemical cycling in plantations; however, how species mixing influences litter decomposition and release of metallic elements from mixed coniferous-broadleaf litter remains unclear. An in situ litter decomposition experiment was conducted to examine the effect of 1) a mixture from coniferous litter (Pinus massoniana) with different individual broadleaved litter (Bretschneidera sinensis, Manglietia chingii, Cercidiphyllum japonicum, Michelia maudiae, Camellia oleifera) and 2) their mixing ratio (mass ratios of coniferous and broadleaf litter of 5:5, 6:4 and 7:3) on the release of metallic elements [calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), manganese (Mn), iron (Fe), copper (Cu) and zinc (Zn)] during litter decomposition. We found that the identity of the broadleaf tree species in the mixed litter and the mixing ratio affected the release rates of metallic elements (p < 0.05). After one year of decomposition, K, Mg, Mn and Zn were released, while Na, Ca, Fe and Cu accumulated in the mixed litter. Mixing increased the release of K, Ca, Na, Mg, Fe, Mn, Cu and Zn in more than one-third of the samples, but inhibited the release of K, Fe and Mn in less than 14% of the samples. Increasing the mixing ratio of coniferous to broadleaf litter enhanced the release of Na, Fe, Mn and Zn but decreased the release of Ca and Mg. Overall, these results highlight that mixed litter, particularly tree species identity and mixing ratio, can alter the release and enrichment of metallic elements during litter decomposition, thereby affecting the cycling of metallic elements in plantations with different species compositions.
阔叶树种在针叶林中的种植已被证明能促进人工林的生物地球化学循环；然而，种间混合如何影响混合针叶-阔叶凋落物的分解以及金属元素的释放仍不清楚。本研究采用原地凋落物分解实验，研究了 1）不同个体阔叶凋落物（中华楠、伯乐树、连香树、醉香含笑、油茶）与针叶凋落物（马尾松）的混合物，以及 2）它们的混合比例（针叶和阔叶凋落物的质量比为 5:5、6:4 和 7:3）对凋落物分解过程中金属元素（钙（Ca）、镁（Mg）、钠（Na）、钾（K）、锰（Mn）、铁（Fe）、铜（Cu）和锌（Zn））释放的影响。结果表明，混合凋落物中阔叶树种的种类和混合比例影响金属元素的释放率（p < 0.05）。经过一年的分解，K、Mg、Mn 和 Zn 被释放出来，而 Na、Ca、Fe 和 Cu 在混合凋落物中积累。混合增加了超过三分之一样本中 K、Ca、Na、Mg、Fe、Mn、Cu 和 Zn 的释放，但抑制了不到 14%样本中 K、Fe 和 Mn 的释放。增加针叶到阔叶凋落物的混合比例增强了 Na、Fe、Mn 和 Zn 的释放，但降低了 Ca 和 Mg 的释放。总的来说，这些结果强调了混合凋落物，特别是树种的种类和混合比例，可以改变凋落物分解过程中金属元素的释放和富集，从而影响不同物种组成的人工林金属元素的循环。
