干旱会减少近期植物光合产物融入土壤食物网的程度，无论其营养复杂性如何,Global Change Biology

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干旱会减少近期植物光合产物融入土壤食物网的程度，无论其营养复杂性如何
Global Change Biology ( IF 10.8 ) Pub Date : 2019-08-10 , DOI: 10.1111/gcb.14754
Mathilde Chomel ₁ , Jocelyn M Lavallee _{1,

2} , Nil Alvarez-Segura ₃ , Francisco de Castro ₄ , Jennifer M Rhymes _{1,

5} , Tancredi Caruso ₆ , Franciska T de Vries ₇ , Elizabeth M Baggs ₈ , Mark C Emmerson ₆ , Richard D Bardgett ₁ , David Johnson ₁

Affiliation

理论表明，更复杂的食物网可以促进稳定性，并可以缓冲干旱等扰动对土壤生物和生态系统功能的影响。在这里，我们通过实验测试了土壤食物网营养复杂性如何调节与碳循环相关的土壤功能对干旱的响应以及植物近期光合产物的捕获和转移到地下。我们构建了由具有一级、二级或三级营养级（微生物、食腐动物和捕食者）的土壤群落组成的实验系统，并使它们遭受干旱。我们研究了食物网营养复杂性与干旱相互作用如何影响凋落物分解、土壤CO ₂流出、菌根定植、真菌生产、微生物群落和土壤动物生物量。干旱后用¹³ C-CO ₂对植物进行脉冲标记，以量化近期光合产物的捕获及其地下转移。总体而言，我们的结果表明，干旱和土壤食物网营养复杂性不会相互作用影响土壤功能和微生物群落组成，而是独立作用，总体上干旱的影响更强。^{干旱后，植物对13} C的净吸收减少，植物生物量中的 13 C 保留量增加，导致地下碳转移大幅减少。尽管食物网营养复杂性影响跳虫的生物量和真菌菌丝长度，但¹³ C富集和碳从植物芽到微生物的净转移以及土壤CO ₂流出并未因营养群数量的变化而受到显着影响。我们的结果表明，干旱通过减少近期光合产物的流动，对地上与地下的联系产生强烈影响。我们的结果强调了近期光合产物从植物转移到土壤生物的关键途径对干旱扰动的敏感性，并表明这些影响可能不会因土壤群落的营养复杂性而减轻，至少在本实验中操纵的水平上是如此。

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Drought decreases incorporation of recent plant photosynthate into soil food webs regardless of their trophic complexity

Theory suggests that more complex food webs promote stability and can buffer the effects of perturbations, such as drought, on soil organisms and ecosystem functions. Here, we tested experimentally how soil food web trophic complexity modulates the response to drought of soil functions related to carbon cycling and the capture and transfer below‐ground of recent photosynthate by plants. We constructed experimental systems comprising soil communities with one, two or three trophic levels (microorganisms, detritivores and predators) and subjected them to drought. We investigated how food web trophic complexity in interaction with drought influenced litter decomposition, soil CO₂ efflux, mycorrhizal colonization, fungal production, microbial communities and soil fauna biomass. Plants were pulse‐labelled after the drought with ¹³C‐CO₂ to quantify the capture of recent photosynthate and its transfer below‐ground. Overall, our results show that drought and soil food web trophic complexity do not interact to affect soil functions and microbial community composition, but act independently, with an overall stronger effect of drought. After drought, the net uptake of ¹³C by plants was reduced and its retention in plant biomass was greater, leading to a strong decrease in carbon transfer below‐ground. Although food web trophic complexity influenced the biomass of Collembola and fungal hyphal length, ¹³C enrichment and the net transfer of carbon from plant shoots to microbes and soil CO₂ efflux were not affected significantly by varying the number of trophic groups. Our results indicate that drought has a strong effect on above‐ground–below‐ground linkages by reducing the flow of recent photosynthate. Our results emphasize the sensitivity of the critical pathway of recent photosynthate transfer from plants to soil organisms to a drought perturbation, and show that these effects may not be mitigated by the trophic complexity of soil communities, at least at the level manipulated in this experiment.

更新日期：2019-08-10

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