Root and mycorrhizal strategies for nutrient acquisition in forests under nitrogen deposition: A meta-analysis
Root and mycorrhizal strategies for nutrient acquisition in forests under nitrogen deposition: A meta-analysis
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DOI：
10.1016/j.soilbio.2021.108418
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发表时间：
2021-12
影响因子：
9.7
通讯作者：
Xiaomin Ma;B. Zhu;Yanxia Nie;Yuan Liu;Y. Kuzyakov
中科院分区：
文献类型：
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作者：
Xiaomin Ma;B. Zhu;Yanxia Nie;Yuan Liu;Y. Kuzyakov
全球氮（N）沉降的增加影响植物光合产物的地下分配、根系和根际相关共生体的形成以及土壤养分的可用性，从而影响树木对养分的获取。树木主要通过细根生长或菌根共生获取营养。这两种机制具有拮抗关系，但氮沉积如何改变它们仍然未知。丛枝菌根（AM）和外生菌根（EM）是菌根真菌的两种主要类型，与大多数树木的根部形成共生。然而，与AM（AM树）或与EM（EM树）共生关系的树木响应氮沉降的不同适应机制和养分获取策略尚不清楚。为了阐明这些观点，我们对 116 项全球森林生态系统研究进行了荟萃分析。在长期（>2年）或高负荷（>140 kg ha−1y−1）氮添加后，AM和EM树都会减少分配给菌根共生体的能量，并越来越依赖细根来获取养分。在氮沉降下，AM 树比 EM 树生长更快，部分原因在于它们不同的养分获取策略：EM 树的细根生物量和长度显着下降（分别为 -13% 和 -17%），但 AM 树则不然。此外，AM 树的酸性磷酸酶活性比 EM 树增加更多（分别为 28% 和 4%），表明添加 N 后，AM 树比 EM 树的有效磷含量更高。因此，AM 树在根系形态和磷酸酶活性方面比 EM 树具有优势，表明它们更好地适应高氮沉降。
Global increase in nitrogen (N) deposition influences the belowground allocation of plant photosynthates and the formation of roots and rhizosphere-associated symbionts as well as soil nutrient availability, thereby affecting the nutrient acquisition by trees. Trees obtain nutrients primarily through fine root growth or mycorrhizal symbioses. These two mechanisms have an antagonistic relationship, but how they are modified by N deposition remains unknown. Arbuscular mycorrhizae (AM) and ectomycorrhizae (EM) are the two dominant types of mycorrhizal fungi that form symbioses with the roots of most trees. However, the divergent adaptive mechanisms and nutrient acquisition strategies of trees with a symbiotic relationship with AM (AM trees) or with EM (EM trees) in response to N deposition are unclear. To clarify these points, we conducted a meta-analysis of 116 studies on global forest ecosystems. Following prolonged (>2 years) or high-load (>140 kg ha−1y−1) N addition, both AM and EM trees decrease the amount of energy allocated to mycorrhizal symbioses and increasingly rely on fine roots to obtain nutrients. The faster growth of AM trees than of EM trees under N deposition is partly attributed to their divergent nutrient acquisition strategies: the fine root biomass and length decreased significantly in EM trees (−13% and −17%, respectively), but not in AM trees. Furthermore, the acid phosphatase activity increased more for the AM trees than for the EM trees (28% and 4%, respectively), indicative of a greater abundance of available P for the AM trees than for the EM trees after N addition. Consequently, AM trees have advantages in terms of root morphology and phosphatase activity over EM trees, suggesting they are better adapted to high N deposition.