杉木和米槠人工林细根形态对短期氮和磷添加的可塑性响应

Plasticity Response of Fine Root Morphological Traits to Short-term Nitrogen and Phosphorus Addition in Subtropical Cunninghamia lanceolata and Castanopsis carleisii Plantations

摘要:

以福建三明地区林龄相似的丛枝菌根树种杉木(Cunninghamia lanceolata)人工林和外生菌根树种米槠(Castanopsis carleisii)人工林为研究对象，采用短期氮添加与根袋法探讨氮和磷添加对不同菌根类型树种细根形态性状的影响。结果表明, 杉木细根的直径与组织密度表现出显著正的氮和磷可塑性响应，比根长和比表面积表现出负的氮和磷可塑性响应，而米槠细根的各形态性状均表现出与杉木相反的氮和磷可塑性响应方向；杉木细根形态性状的磷可塑性响应更强，米槠细根形态性状的氮和磷可塑性响应间无显著差异。细根同一形态性状对氮和磷添加的可塑性响应间的方向相同，且具有正相关关系；细根不同形态性状的养分塑性响应间存在着协同与权衡关系。因此，丛枝菌根树种杉木采取了延长细根寿命的资源保守型策略，而外生菌根树种米槠采取快速占有资源的资源获取型策略。此外，杉木和米槠细根对氮和磷添加可能均具有相同的觅食趋向，且杉木细根形态性状对磷添加更敏感。

Abstract:

Taking similar age arbuscular mycorrhiza (AM) species Cunninghamia lanceolata and ectotrophic mycorrhiza (EM) species Castanopsis carlesii in Sanming, Fujian Province as the research objects, the effects of nitrogen and phosphorus addition on morphological characteristics of fine roots of different mycorrhizal species were studied. The results showed that the diameter and root tissue density of fine roots of Cunninghamia lanceolata had significantly positive N and P plasticity response, and the specific root length and specific surface area had negative plasticity response, while the morphological traits of fine roots of Castanopsis carlesii showed opposite plasticity response. The P plasticity response of fine root morphological traits of Cunninghamia lanceolata was stronger than that of Castanopsis carlesii, but there was no significant difference between N and P plastic responses of fine root morphological traits of Castanopsis carlesii. The direction of plasticity response of the same morphological trait of fine root to N and P was the same, and there was a positive correlation. There was synergistic and tradeoff relationship between nutrient plasticity responses of different morphological characters in fine roots. Therefore, AM species Cunninghamia lanceolata adopted the resource conservation strategy to prolong the fine rootlife, while the EM species Castanopsis carlesii adopted the resource acquisition strategy to occupy resources quickly. In addition, the fine roots of AM species Cunninghamia lanceolata and the EM species Castanopsis carlesii might have the same foraging trend to N and P addition, and morphological traits of AM species Cunninghamia lanceolata fine roots were more sensitive to P addition than EM species Castanopsis carlesii.