Decoupling the direct and indirect effects of climate on plant litter decomposition: Accounting for stress‐induced modifications in plant chemistry
Decoupling the direct and indirect effects of climate on plant litter decomposition: Accounting for stress‐induced modifications in plant chemistry
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DOI：
10.1111/gcb.13923
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发表时间：
2018-04
影响因子：
11.6
通讯作者：
V. Suseela;N. Tharayil
中科院分区：
文献类型：
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作者：
V. Suseela;N. Tharayil
植物凋落物的分解是一个基本的生态系统过程，可以作为气候变化的反馈，同时影响生态系统的生产力和土壤中二氧化碳的通量。从衰老后的角度来看，气候对分解的影响是相对众所周知的;特别是，气候是已知的调节凋落物分解的速率，通过其直接影响的反应动力学和微生物生理学的过程下游的组织衰老。气候可以改变植物组织形成阶段的新陈代谢，并可以形成可用于分解的植物凋落物的最终化学成分，从而间接影响分解;然而，这些间接影响相对知之甚少。气候胁迫破坏植物细胞内稳态，导致初级和次级代谢途径的重新编程，这导致植物组织基质内小分子和不饱和杂聚物（包括木质素、单宁、木栓质和角质层）的数量、组成和组织的变化。此外，通过调节组织衰老期间的代谢，气候影响衰老组织对营养物质的再吸收。因此，形成分解基质的植物凋落物的最终化学组成是通过代谢物的产生和再吸收的衰老生理过程的组合产物。凋落物分子结构的数量、组成和定位的变化可以通过各种络合反应改变木质纤维素基质的可降解性、微生物群落的组成和微生物胞外酶的活性，从而促进或阻碍组织分解和土壤养分循环。此外，气候引起的凋落物分子组成的变化可能会对凋落物分解和土壤养分循环产生不同的影响。与温带生态系统相比，气候对热带凋落物分解的间接影响还没有得到很好的理解，这突出了在热带生物群落中进行更多研究的必要性。我们还强调需要关注气候胁迫如何影响根系化学，因为根系对土壤地球化学循环有重要贡献，并利用更强大的分析方法来捕获组织基质的分子组成，为微生物代谢提供燃料。
Decomposition of plant litter is a fundamental ecosystem process that can act as a feedback to climate change by simultaneously influencing both the productivity of ecosystems and the flux of carbon dioxide from the soil. The influence of climate on decomposition from a postsenescence perspective is relatively well known; in particular, climate is known to regulate the rate of litter decomposition via its direct influence on the reaction kinetics and microbial physiology on processes downstream of tissue senescence. Climate can alter plant metabolism during the formative stage of tissues and could shape the final chemical composition of plant litter that is available for decomposition, and thus indirectly influence decomposition; however, these indirect effects are relatively poorly understood. Climatic stress disrupts cellular homeostasis in plants and results in the reprogramming of primary and secondary metabolic pathways, which leads to changes in the quantity, composition, and organization of small molecules and recalcitrant heteropolymers, including lignins, tannins, suberins, and cuticle within the plant tissue matrix. Furthermore, by regulating metabolism during tissue senescence, climate influences the resorption of nutrients from senescing tissues. Thus, the final chemical composition of plant litter that forms the substrate of decomposition is a combined product of presenescence physiological processes through the production and resorption of metabolites. The changes in quantity, composition, and localization of the molecular construct of the litter could enhance or hinder tissue decomposition and soil nutrient cycling by altering the recalcitrance of the lignocellulose matrix, the composition of microbial communities, and the activity of microbial exo‐enzymes via various complexation reactions. Also, the climate‐induced changes in the molecular composition of litter could differentially influence litter decomposition and soil nutrient cycling. Compared with temperate ecosystems, the indirect effects of climate on litter decomposition in the tropics are not well understood, which underscores the need to conduct additional studies in tropical biomes. We also emphasize the need to focus on how climatic stress affects the root chemistry as roots contribute significantly to biogeochemical cycling, and on utilizing more robust analytical approaches to capture the molecular composition of tissue matrix that fuel microbial metabolism.