摘要:农田生态系统是陆地生态系统的重要组成部分，在维系生命的生长发育和环境的动态平衡等方面起着至关重要的作用，在其生长发育和环境演变的过程中储存大量的环境变化信息，能够反映古农业的发展变迁。植硅体是一种长期稳定存在于土壤中的非晶质二氧化硅颗粒物，它可以指示气候变化。近年来，植硅体分析主要应用在农业考古、古气候重建、生物地球化学循环和全球碳汇潜力估算的研究中。世界上作物分布广泛，作物栽培历史悠久，研究作物植硅体与植硅体碳，对探讨农业起源与发展，估算农田生态系统植硅体碳汇潜力，应对全球气候变化具有重要意义。本文在查阅国内外与作物植硅体研究相关文献的基础上，综述了作物植硅体的形态研究、植硅体在考古学中的应用、作物植硅体碳含量与分布、碳汇潜力以及植硅体碳汇在全球碳汇中的贡献，阐明了作物植硅体未来的研究方向。1）不同作物产生的植硅体形态不同，而且对作物植硅体形态的研究较多处于优势的禾本科中，其他作物的研究较少；2）作物植硅体碳含量与其本身的固碳能力和效率有关，不完全由植硅体含量的多少决定，此外，植硅体碳含量的多少也可能受生长环境和植物基因型的影响；3）不同生态系统中气候、地表植被、土壤环境等诸多因素直接或间接地影响区域植硅体的碳汇潜力；4）农田生态系统不同作物植硅体碳汇存在显著差异，施加硅肥或硅-磷复合肥、种植高植硅体含量和高植硅体碳含量的作物等均可显著提高农田生态系统碳汇潜力。今后应进一步研究不同作物植硅体碳汇，以帮助识别过去的农业碳汇，评估当前农业碳汇潜力；加强植物、根系、土壤迁移规律的探讨，进一步分析不同作物植硅体积累与碳汇效应；阐明不同植物吸硅机制、植物根系硅化过程与其植硅体含量、植硅体碳含量间的关系；了解西南喀斯特生态脆弱区农业碳汇潜力，以期为作物科学种植、农田生态系统碳汇估算等提供参考。
关键词:作物/
植硅体/
植硅体碳/
碳汇/
农田生态系统
Abstract:Farmland ecosystems are important for maintaining terrestrial ecosystems and environmental homeostasis. As farmland ecosystems develop and evolve, change information is stored in the environment such as in phytoliths, which are stable, non-crystalline minerals in the soil that can indicate climate change. Phytolith analysis has been used for agricultural archaeology, paleoclimate reconstruction, and for estimating biogeochemical cycles and global carbon sequestration potential. Crop cultivation has a long history, and crops are globally distributed. Therefore, studying crop phytoliths and phytolith-occluded carbon is useful for exploring the origin and development of agriculture, estimating farmland ecosystem carbon sequestration, and responding to global climate change. The content and distribution of phytolith-occluded carbon, the phytolith carbon sequestration potential, and the contribution to global carbon sequestrations were analyzed (by literature review and phytolith morphological and archaeological information) to determine future crop phytolith research directions. The results showed that crops had differing phytolith characteristics, and most crop phytolith research had been completed in the family Gramineae. The crop phytolith carbon content was correlated to crop's carbon sequestration capacity and efficiency, and the phytolith-occluded carbon content may also be affected by the growth environment and plant genotypes. The climate, surface vegetation, and soil environment of the ecosystem had direct and indirect effects on the regional phytolith carbon sequestration potential. Significant differences in carbon sequestration between farmland crops were observed. Applying a silicon fertilizer or a silicon-phosphorus compound fertilizer and planting crops with high silicon content can significantly improve the carbon sequestration potential. Future studies should investigate the phytolith carbon sequestration of specific crops to identify past carbon sequestration levels and compare them with the current potential. The plant migration law, root systems, and soil should be improved, and crop silicon levels should be analyzed to determine the effect on accumulation volume and carbon sequestration. Future studies should investigate the silicon absorption mechanism, root silicification process, and phytolith-occluded carbon content of crops and the agricultural carbon sequestration potential of the ecologically fragile karst area in Southwest China to improve farmland ecosystem crop planting and carbon sink estimation.
Key words:Crops/
Phytoliths/
Phytolith-occluded carbon (PhytOC)/
Carbon sequestration/
Farmland ecosystem
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