Altered leaf litter quality exacerbates the negative impact of climate change on decomposition
Altered leaf litter quality exacerbates the negative impact of climate change on decomposition
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DOI：
10.1111/1365-2745.13168
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发表时间：
2019-04
影响因子：
5.5
通讯作者：
I. Prieto;M. Almagro;F. Bastida;J. Querejeta
中科院分区：
文献类型：
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作者：
I. Prieto;M. Almagro;F. Bastida;J. Querejeta
凋落物分解是全球生态地球化学循环的重要组成部分，影响着土壤碳储量、养分有效性和植物生产力。持续的气候变化将导致许多干旱地区出现更温暖和更干燥的状况，可能影响到凋落物的分解和养分动态。气候变化的影响可以是直接和/或间接的，例如通过改变凋落物质量，但其对凋落物分解的相对重要性仍不清楚。我们在半干旱灌丛中进行了一项操作研究，以评估落叶质量的影响，预测气候变化，即+2.5 ° C变暖（W），30%降雨量减少（RR）以及它们的相互作用（W + RR），以阐明它们对落叶分解的相对影响。单独的气候效应减少了分解的均匀控制落叶从Heliodiumsquamatum灌木生长在未经处理的地块分别由23.4%，18.1%和29.8%，在W，RR和W + RR治疗。落叶质量较低的灌木，一直在温暖的地块（W和W + RR），因为他们有较低的营养物质浓度（P，Fe）和较高的C：N和C：P比落叶在环境（对照）条件下产生的。木质素浓度显着降低凋落物从W + RR地块，但同时考虑气候和凋落物质量，分解率分别为32.0%，26.3%和39.9%，降低在W，RR和W + RR地块相比，控制。此外，我们发现更大的微生物N固定在落叶温育（W和W + RR）比非温暖的地块（对照和RR）。结构方程模型表明，较高的凋落物水分和微生物生物量含量刺激分解。模拟气候变化（W，RR和W + RR）减少分解间接的凋落物水分含量和凋落物微生物生物量的负面影响。微生物氮固定的刺激质量较低（即高C：N比）的落叶收集灌木温暖的地块（W和W + RR）。合成.我们的研究结果表明，预测的气候变化条件减缓了旱地生态系统中的C和N循环，气候变化引起的凋落物质量下降以及凋落物中细菌和真菌生物量的相关减少进一步加剧了这种影响。
Leaf litter decomposition is a key component of global biogeochemical cycles that influence soil carbon storage, nutrient availability and plant productivity. Ongoing climate change will lead to warmer and drier conditions in many dryland regions, potentially affecting litter decomposition and nutrient dynamics. Climate change effects can be direct and/or indirect, for example, through changes in litter quality, yet their relative importance on litter decomposition remains unclear. We conducted a manipulative study in a semi‐arid shrubland to assess the effects of leaf litter quality, forecasted climate change, that is, +2.5°C warming (W), 30% rainfall reduction (RR) as well as their interaction (W + RR) to elucidate their relative effects on litter decomposition. Climatic effects alone reduced decomposition of a homogeneous Control leaf litter collected from Helianthemum squamatum shrubs growing in unmanipulated plots by 23.4%, 18.1% and 29.8% in the W, RR and W + RR treatments respectively. Leaf litter quality was lower in shrubs that had been growing in warmed plots (W and W + RR), as they had lower nutrient concentrations (P, Fe) and higher C:N and C:P ratios than leaf litter produced under ambient (Control) conditions. Lignin concentration was significantly lower in litter from W + RR plots, yet when both climate and litter quality were considered simultaneously, decomposition rates were 32.0%, 26.3% and 39.9% lower in W, RR and W + RR plots compared to Controls. In addition, we found greater microbial N immobilization in leaf litter incubated within warmed (W and W + RR) than within non‐warmed plots (Control and RR). Structural equation modelling showed that higher litter moisture and microbial biomass contents stimulated decomposition. Simulated climate change (W, RR and W + RR) reduced decomposition indirectly by negatively affecting litter moisture contents and litter microbial biomass. Microbial nitrogen immobilization was stimulated by the lower quality (i.e. high C:N ratios) of the leaf litter collected in shrubs from warmed plots (W and W + RR). Synthesis. Our findings indicate that forecasted climate change conditions slow down C and N cycling in a dryland ecosystem, an effect that is further exacerbated by climate change‐induced reductions in litter quality and related reductions in bacterial and fungal biomass in litter.