Lange Markus, Eisenhauer Nico, Chen Hongmei, Gleixner Gerd
Max Planck Institute for Biogeochemistry, Jena, Germany.
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
Glob Chang Biol. 2023 May;29(9):2627-2639. doi: 10.1111/gcb.16641. Epub 2023 Mar 1.
Soils are important for ecosystem functioning and service provisioning. Soil communities and their functions, in turn, are strongly promoted by plant diversity, and such positive effects strengthen with time. However, plant diversity effects on soil organic matter have mostly been investigated in the topsoil, and there are only very few long-term studies. Thus, it remains unclear if plant diversity effects strengthen with time and to which depth these effects extend. Here, we repeatedly sampled soil to 1 m depth in a long-term grassland biodiversity experiment. We investigated how plant diversity impacted soil organic carbon and nitrogen concentrations and stocks and their stable isotopes C and N, as well as how these effects changed after 5, 10, and 14 years. We found that higher plant diversity increased carbon and nitrogen storage in the topsoil since the establishment of the experiment. Stable isotopes revealed that these increases were associated with new plant-derived inputs, resulting in less processed and less decomposed soil organic matter. In subsoils, mainly the presence of specific plant functional groups drove organic matter dynamics. For example, the presence of deep-rooting tall herbs decreased carbon concentrations, most probably through stimulating soil organic matter decomposition. Moreover, plant diversity effects on soil organic matter became stronger in topsoil over time and reached subsoil layers, while the effects of specific plant functional groups in subsoil progressively diminished over time. Our results indicate that after changing the soil system the pathways of organic matter transfer to the subsoil need time to establish. In our grassland system, organic matter storage in subsoils was driven by the redistribution of already stored soil organic matter from the topsoil to deeper soil layers, for example, via bioturbation or dissolved organic matter. Therefore, managing plant diversity may, thus, have significant implications for subsoil carbon storage and other critical ecosystem services.
土壤对于生态系统功能和服务的提供至关重要。反过来，植物多样性有力地促进了土壤群落及其功能，并且这种积极影响会随着时间的推移而增强。然而，植物多样性对土壤有机质的影响大多是在表层土壤中进行研究的，长期研究非常少。因此，尚不清楚植物多样性的影响是否会随着时间增强，以及这些影响会延伸到多深的土层。在这里，我们在一个长期的草地生物多样性实验中，对1米深度的土壤进行了反复采样。我们研究了植物多样性如何影响土壤有机碳和氮的浓度及储量以及它们的稳定同位素碳和氮，以及这些影响在5年、10年和14年后如何变化。我们发现，自实验建立以来，较高的植物多样性增加了表层土壤中的碳和氮储量。稳定同位素表明，这些增加与新的植物源输入有关，导致土壤有机质的加工和分解减少。在底土中，主要是特定植物功能群的存在驱动了有机质动态。例如，深根高草的存在降低了碳浓度，很可能是通过刺激土壤有机质分解。此外，随着时间的推移，植物多样性对表层土壤有机质的影响变得更强，并延伸到底土层，而底土中特定植物功能群的影响则随着时间逐渐减弱。我们的结果表明，改变土壤系统后，有机质向底土转移的途径需要时间来建立。在我们的草地系统中，底土中的有机质储存是由表层土壤中已储存的土壤有机质重新分配到更深土层驱动的，例如通过生物扰动或溶解有机质。因此，管理植物多样性可能对底土碳储存和其他关键生态系统服务具有重要意义。
