Nitrogen and Phosphorus Contents and Reabsorption Characteristics of Different Tree Species in A Subtropical Homogeneous Garden
Assessing the nitrogen(N)and phosphorus(P)contents,as well as the reabsorption characteristics of plants,proves to be a valuable approach for unveiling nutrient utilization strategies in forest trees.However,previous work on this topic is still very limited.To address this knowledge gap,we selected seven broad-leaved tree species plantations as research objects in a subtropical homogeneous garden,including Cinnamomum platyphyllum,C.longepaniculatum,C.camphora,Toona sinensis,T.ciliate,C.japonicum and Alnus cremastogyne.We collected samples of branches and leaves in green and senescent,to determine the N and P contents and calculated reabsorption efficiency.The results showed that:(1)The N and P contents in the green leaves and senescent leaves of T.ciliate,Toona sinensis,and Alnus cremastogyne were generally higher than those in other tree species.Conversely,the N content in the green branches and senescent branches of Alnus cremastogyne was significantly higher than that of other tree species,while its P content exhibited the opposite trend.All tree branches and leaves had ratios less than 14,indicating that N was the primary limiting nutrient for the species in this area.(2)The green leaf N-to-P allometric index was 0.744,following the 2/3 rule of N-P stoichiometry,while the green branches and senescent branches and leaves deviated from this pattern.Compared to green branches and leaves,N elements in senescent branches and leaves exhibited greater variability,while their P elements followed an opposing trend.(3)The N reabsorption efficiency in branches and leaves of Alnus cremastogyne,T.ciliate and Toona sinensis was significantly lower than that of other trees(with the exception of Toona sinensis branches).Conversely,the P reabsorption efficiency in branches and leaves was higher overall compared to other trees(except for Alnus cremastogyne branches).(4)The N-to-P stoichiometry in leaves was primarily influenced by a combination of tree characteristics and soil physicochemical properties,whereas branches were mainly affected by soil physicochemical properties.Our findings suggested that,in comparison to other native tree species,the deciduous varieties such as Alnus cremastogyne and T.ciliate be selected as reforestation species for mixed artificial forests to enhance the quality of subtropical artificial forests.
homogeneous gardenartificial forestsnative tree speciesnitrogen and phosphorus stoichiometrynutrient reabsorption efficiency
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