Purpose

The lack of synchronous studies on fine roots and fungal hyphae makes it difficult to gain insight into changes in how mycorrhizal trees search for nutrients under reduced precipitation and increased nitrogen deposition.

Methods

We applied a modified version of the ingrowth bag approach to estimate the community-level responses of fine roots and fungal hyphae to long-term changes in nitrogen and water availability in a mixed mature forest.

Results

Water reduction, nitrogen addition and the two treatments applied in combination decreased root length density, root biomass and fungal hyphal length density, with the lowest values occurring in the combined treatment. Compared with fine roots in the control treatment, fine roots in the water reduction treatment had a thinner diameter, lower branching intensity and a greater specific root length. Fungal hyphae in the combined treatment had significantly greater diameters than in the control treatment at 0–10 cm soil depths. Root length density, root biomass, root branching intensity and hyphal length density significantly decreased with increasing soil depth. In contrast, hyphal diameter increased with increasing soil depth. Fungal hyphal length density was positively related to root length density but negatively related to hyphal diameter.

Conclusion

Forest fine roots and fungal hyphae respond plastically to soil water and nitrogen availability. An integrative and simultaneous understanding of both root and hyphal trait plasticity can provide better insights into the resource acquisition strategies of trees experiencing environmental changes.

中文翻译：

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长期减水增氮对红松混交林细根和真菌菌丝的影响

目的

由于缺乏对细根和真菌菌丝的同步研究，因此很难深入了解菌根树在降水减少和氮沉积增加的情况下如何寻找养分的变化。

方法

我们应用了改进版的向内生长袋方法来估计细根和真菌菌丝对混合成熟林中氮和水可用性的长期变化的社区水平响应。

结果

减水、加氮和联合应用的两种处理降低了根长密度、根生物量和真菌菌丝长密度，联合处理中的值最低。与对照处理细根相比，减水处理细根直径更细，分枝强度更低，比根长更大。在 0-10 cm 土壤深度，联合处理中的真菌菌丝直径明显大于对照处理。根长密度、根生物量、根分枝强度和菌丝长密度随着土壤深度的增加而显着降低。相反，菌丝直径随着土壤深度的增加而增加。真菌菌丝长度密度与根长密度呈正相关，与菌丝直径呈负相关。

结论

森林细根和真菌菌丝对土壤水和氮的有效性做出可塑性反应。对根和菌丝性状可塑性的综合和同时理解可以更好地了解经历环境变化的树木的资源获取策略。