Evidence for a fungal loop in shrublands
Evidence for a fungal loop in shrublands
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DOI：
10.1111/1365-2745.13610
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发表时间：
2021-02
影响因子：
5.5
通讯作者：
Niko Carvajal Janke;K. Coe
中科院分区：
文献类型：
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作者：
Niko Carvajal Janke;K. Coe
旱地群落可以通过地下真菌连接（称为真菌循环）交换养分，从而减轻有限资源的损失。在干旱草原中，真菌循环可以影响群落组成和初级生产力，但它们在整个旱地系统中的生态意义仍有待探索。我们研究了北美灌木丛生态系统中真菌循环在养分转运中的功能作用。我们追踪了 15N 从苔藓为主的生物结皮到主要的旱生灌木 Larrea tridentata 的移动，以及 13C 从 L. tridentata 到索诺兰沙漠原位建立的生物结皮的移动。测量在模拟 2.5 毫米降雨事件后 1 周内的三个时间点进行，测量距离示踪剂应用最远 1 m。我们还使用 ITS 测序来研究 1 周内土壤中真菌群落组成的变化。我们发现 15N 从生物结皮移动到 L. tridentata 叶子，以及 15N 移动到其他空间隔离的苔藓为主的生物结皮斑块，但这种移动直到降雨后 4-6 天才发生，此时与前几天相比，在 L. tridentata 和生物结皮中观察到明显更高的 δ15N。我们没有观察到从 L. tridentata 到邻近灌木或生物结皮的 13C 移动的一致模式，这表明该系统中碳移动的环境驱动因素不同。在研究的最后一天，真菌群落表现出阿尔法多样性的下降，表明群落对降雨的反应延迟并伴随养分转移。内生真菌目 Pleosporales 和 Pezizales 在所有样地土壤中占主导地位，并且 Pleosporales 目在 15N 富集的样地中显着更丰富，表明深色有隔内生真菌参与氮转运。养分转运的延迟可能反映了干旱后降雨引发的群落成员之间菌丝网络的重建。合成。我们的结果指出了以前未调查的植被类型（灌木丛）中真菌介导的养分交换途径，其中养分在苔藓为主的生物结皮和附近的灌木之间转移。我们提供了第一个证据，表明降雨后养分转移可能会延迟长达 6 天，这与旱地的脉冲动态响应一致，并且以苔藓为主的生物结皮在真菌循环中发挥着作用。
Dryland communities may mitigate the loss of limited resources by exchanging nutrients through subterranean fungal connections, termed fungal loops. In arid grasslands, fungal loops can influence community composition and primary productivity, yet their ecological significance across dryland systems remains unexplored. We investigated the functional role of fungal loops in nutrient translocation in a North American shrubland ecosystem. We traced the movement of 15N from moss‐dominated biocrusts to the dominant xeric shrub Larrea tridentata, and the movement of 13C from L. tridentata to biocrusts in plots established in situ in the Sonoran Desert. Measurements occurred at three time points spanning 1 week following a simulated 2.5 mm rainfall event, and at distances up to 1 m from tracer application. We also used ITS sequencing to investigate changes in fungal community composition in soils over the 1‐week period. We discovered movement of 15N from biocrusts into L. tridentata foliage as well as 15N movement to other spatially isolated moss‐dominated biocrust patches, yet this movement did not occur until 4–6 days post‐rainfall, when significantly higher δ15N was observed in L. tridentata and biocrusts compared to previous days. We did not observe consistent patterns of 13C movement from L. tridentata into neighbouring shrubs or biocrusts, suggesting differential environmental drivers for carbon movement in this system. Fungal communities exhibited a decrease in alpha diversity on the last day of the study, indicative of a delayed community response to rainfall concomitant with nutrient translocation. Fungal endophyte orders Pleosporales and Pezizales dominated all plot soils, and order Pleosporales was significantly more abundant in 15N enriched plots, suggesting that dark septate endophytic fungi were involved in nitrogen translocation. The delay in nutrient translocation may reflect a rainfall‐triggered rebuilding of mycelial networks between community members following drought. Synthesis. Our results point to fungal‐mediated nutrient exchange pathways in a previously uninvestigated vegetation type, shrublands, where nutrients are translocated between moss‐dominated biocrusts and nearby shrubs. We provide the first evidence that nutrient transfer may be delayed up to 6 days following rainfall, consistent with pulse‐dynamic responses in drylands, and that moss‐dominated biocrusts play a role in fungal loops.