不同生境中鬼针草(Bidens pilosa)碳氮磷化学计量特征及其营养利用策略

Carbon, nitrogen and phosphorus stoichiometric characteristics of alien species Bidens pilosa from different habitats and strategy on their nutrient utilization

关键词:  鬼针草, 化学计量特征, 营养利用策略, 生长速率, 入侵性

Key words:  Bidens pilosa, stoichiometric characteristics, nutrient utilization strategy, growth rate, invasion

摘要:

该研究通过野外采样和实验室测定的方法,研究了三种生境中鬼针草叶和根碳(C)、氮(N)、磷(P)化学计量特征及其与土壤养分的相关性。结果表明:(1)鬼针草的生境具有不同的资源水平。三种生境的土壤全氮(TN)和速效氮贫乏,有机碳(C)和全磷(TP)较充裕; 生境Ⅰ土壤TN含量显著低于其它两个生境,生境II土壤TP含量显著低于其它两个生境,生境III土壤TN、TP含量均大于其它两个生境。(2)不同生境的鬼针草对磷(P)分配策略不同。低N生境的鬼针草叶片P含量>根P含量, P较多地分配到植物体地上部分; N、P含量较高的生境中鬼针草根P含量>叶P含量,P更多地分配到地下部分。(3)不同生境的鬼针草其地上部分和根的生长速率不同。低N生境的鬼针草叶片N/P和C/P值小,植物体具有较高的相对生长速率,具有地上生长竞争优势; 低P生境的植物叶片N/P和C/P值大,植物体具有较慢的相对生长速率; 高N、高P生境中根N/P和C/P值小,根具有较高的生长速率,保证了鬼针草的地下生长竞争优势。(4)鬼针草叶片N/P和根N/P之间呈现不显著的负相关关系,植物地上部分和地下部分为异速生长。不同生境的鬼针草具有不同的营养利用和分配策略,保证了植物强大的竞争力和入侵性。

Abstract:

In order to reveal the nutrient utilization strategy of the alien species under different habitats, carbon(C), nitrogen(N)and phosphorus(P)stoichiometric characteristics of leaf and root of Bidens pilosa from three habitats and their relations with soil nutrients were analyzed through field sampling and laboratory measuring. Furthermore, the relative growth rate and nutrient utilization strategy under these habitats were also analyzed. The results were as follows:(1)Total nitrogen(TN)and available nitrogen(AN)contents in soils under all three habitats were low, while organic carbon(C)and total phosphorus(TP)were abundant. TN and TP contents of soil, in habitat I and Ⅱ were significantly less than those of the other two habitats, respectively, and both TN and TP in soil of habitat Ⅲ were significantly more than those of the other two habitats.(2)P content of leaf in low-N habitat was more than that of root, which implied that P was more distributed to aboveground of plants. P content of root in habitat with rich-N and -P was more than that of leaf, which showed that more P distributed in the root of plants.(3)There were different growth rates for aboveground part and root of B. pilosa under three habitats. The N/P and C/P values of leaves in low-N habitat were less than that of other two habitats, indicating that B. pilosa in low-N habitats had higher growth rates and more competitive advantage for aboveground part. The N/P and C/P values of leaves in low-P habitat were more than those of other habitats, showing that B. pilosa in low-P habitats has slower relative growth rates. The N/P and C/P of root in both rich-N and rich-P habitat were less than that of two habitats, implying that the root of B. pilosa in these habitats has higher growth rates, and further enables plants to increase competition for belowground part.(4)There was insignificantly negative correlation between leaf N/P and root N/P of B. pilosa, therefore, between aboveground and the underground part of plant were allometry. There are different nutrient utilization and allocation strategies for B. pilosa under different habitats to ensure plants more competitive and invasive.