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研究杨树人工林1~5级根序细根内碳、氮及非结构性碳水化合物含量的季节动态,对比了杨树细根碳氮分配格局的代际差异,以期建立细根生长和功能变化与连作人工林生产力衰退的联系.结果表明:杨树细根非结构性碳水化合物(NSC)随根序显著增加,而氮含量显著减少.细根中全C和NSC含量与全N存在显著相关性.细根碳氮含量的变化在根序间的解释量占98.2%,而在代际间仅为1.7%.杨树不同根序细根均在生长季具有较高的碳含量和较低的氮含量,且碳、氮及NSC含量在代际间随季节差异显著,但C∶N差异不显著,根序与季节对细根碳氮含量存在显著交互效应.杨树低级细根C∶N约为20∶1,高级根则大于30∶1.细根C∶N在生长季(7和9月)显著低于其他季节,NSC含量在11月最高.连作人工林杨树细根的碳氮分配格局与细根根序具有较强的耦合性,NSC和C∶N在指示细根周转和调控细根季节性生长中具有重要生态学意义.
The seasonal dynamics of carbon, nitrogen and unstructured carbohydrate contents in the fine roots of the first to fifth order poplars of poplar plantations were studied. The inter-generational differences of carbon and nitrogen distribution pattern of poplar fine roots were compared to establish the root growth and functional changes The results showed that the fine root non-structural carbohydrates (NSC) of poplar trees increased significantly with the increase of root-mean-square while the content of nitrogen decreased significantly.The contents of total C and NSC in fine roots were significantly correlated with the total N content. The changes of root carbon and nitrogen contents accounted for 98.2% of the total root orders, but only 1.7% of the intergenerational ones. The fine roots of different roots of poplar had higher carbon content and lower nitrogen content during the growing season , And the contents of carbon, nitrogen and NSC were significantly different from seasons in the intergenerational period, but the difference of C: N was not significant, and there was a significant interaction effect between root order and seasons on the contents of carbon and nitrogen in fine roots. 20: 1, and higher roots were greater than 30: 1. The fine root C: N was significantly lower in the growing season (July and September) than in other seasons, with the highest NSC content in November. Roots of fine roots have strong coupling, NSC and C: N are indicative of fine root turnover and regulation of fine root seasonality Of great ecological significance in the long.