State Key Laboratory of Tree Genetics and Breeding, Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangdong 510520, China.
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangdong 510520, China.
Sci Total Environ. 2023 Aug 25;888:164176. doi: 10.1016/j.scitotenv.2023.164176. Epub 2023 May 16.
Hemiparasitic plants influence community composition by altering nutrient cycling. Although hemiparasites can deplete a host's nutrients via parasitism, their potentially positive effects on nutrient return to multispecies communities remain unclear. We used C/N-enriched leaf litter of the hemiparasite sandalwood (Santalum album, Sa) and two N-fixing hosts of acacia (Acacia confusa, Ac) and rosewood (Dalbergia odorifera, Do), either as a single-species or mixed-species litter, to elucidate nutrient return by litter decomposition in an acacia-rosewood-sandalwood mixed plantation. We determined litter decomposition rates, litter C and N release, and the resorption of C and N from seven litter types (Ac, Do, Sa, AcDo, AcSa, DoSa, and AcDoSa) at 90, 180, 270, and 360 days. We found that non-additive mixing effects were common during the decomposition of mixed litter and depended on litter type and decomposition timing. After rapidly increasing for around 180 days, both the decomposition rate and release of C and N from litter decomposition declined, but the resorption of litter-released N by the target tree species increased. There was a 90-day lag time between the release and resorption of litter N. Sandalwood litter consistently stimulated the litter mass loss of its mixed litter. Rosewood had the highest release rate of litter C or N from litter decomposition, but resorbed more litter N into its leaves than other tree species. In contrast, acacia had a lower decomposition rate and a higher N resorption in its roots. Initial litter quality was closely correlated with the release of litter N. Neither the release nor resorption of litter C significantly differed among sandalwood, rosewood, and acacia. Our study demonstrates that the fate of litter N, rather than litter C, mediates nutrient relationships in mixed sandalwood plantations and thus provides important silvicultural implications for planting sandalwood with other host species.
半寄生植物通过改变养分循环来影响群落组成。尽管半寄生植物可以通过寄生耗尽宿主的养分，但它们对多物种群落养分返回的潜在积极影响仍不清楚。我们使用半寄生檀香（Santalum album，Sa）和两种固氮豆科金合欢属植物（Acacia confusa，Ac）和紫檀属植物（Dalbergia odorifera，Do）的 C/N 富集叶凋落物，无论是作为单一物种还是混合物种凋落物，来阐明相思树-紫檀-檀香混交林凋落物分解过程中的养分归还。我们测定了凋落物分解速率、凋落物 C 和 N 释放以及七种凋落物类型（Ac、Do、Sa、AcDo、AcSa、DoSa 和 AcDoSa）从 90、180、270 和 360 天的 C 和 N 再吸收。我们发现，混合凋落物分解过程中普遍存在非加性混合效应，且取决于凋落物类型和分解时间。在快速增加约 180 天后，凋落物分解的分解速率和 C 和 N 的释放都下降，但目标树种对凋落物释放的 N 的再吸收增加。凋落物 N 的释放和再吸收之间有 90 天的滞后时间。檀香凋落物持续刺激其混合凋落物的质量损失。紫檀凋落物从凋落物分解中释放出的 C 或 N 的释放率最高，但与其他树种相比，其叶片再吸收更多的凋落物 N。相比之下，金合欢的分解速率较低，根系对 N 的再吸收较高。初始凋落物质量与凋落物 N 的释放密切相关。檀香、紫檀和金合欢的凋落物 C 或 N 的释放或再吸收均无显著差异。我们的研究表明，凋落物 N 的命运而不是凋落物 C 决定了混交檀香人工林的养分关系，因此为与其他宿主树种种植檀香提供了重要的造林意义。
