【作者】 李茜；

【导师】 陈伏生；

【作者基本信息】 南昌大学 ， 植物学， 2010， 硕士

【摘要】 土壤磷素(P)既是植物生长的关键限制性因子,也是环境污染的潜在来源。城市化作为全球变化的重要内容,如何影响森林生态系统P循环和土壤P含量还知之甚少。本研究以南昌城区-郊区-农村生态梯度的灌丛林、马尾松(Pinus massoniana)林、湿地松(Pinus elliottii)林、针阔混交林、常绿阔叶林、毛竹(Phyllostachys edulis)林为研究对象,采用改进Hedley的P连续浸提法分析了土壤不同功能P形态的时空规律,以及湿地松针叶P含量的季节动态和再吸收效率。结果表明：(1)位于南昌城区-郊区-农村梯度上的39块林地土壤全P及各功能P形态总体上表现城区含量较高,郊区居中,农村较低,说明城市化会导致森林土壤全P及不同功能形态P的积累。(2)位于南昌城乡梯度上的灌丛林、马尾松林、针阔混交林、常绿阔叶林、毛竹林林地土壤不同功能P形态的平均值表现为：HCl-P是城区土壤P功能形态的主要成分,达到36%,NaOH-P是郊区和农村的主体,分别为42%和50%；而位于城区、郊区和农村的湿地松林土壤不同功能P形态的年均值均表现为NaOH-P是主体,分别占52%、58%和53%。这说明城乡森林土壤P输入形态有别,且城区外源性P输入具有很高的空间异质性。(3)位于南昌城乡梯度上的5种中亚热带森林演替典型阶段的30块林地土壤不同功能P形态的平均值总体上表现为：人为活动较高频率的灌丛林和毛竹林显著高于人为活动较低的马尾松林、针阔混交林、常绿阔叶林,说明人为干扰是影响土壤P含量及其形态组成的关键因素,而森林的自然演替对P循环及土壤P有效性的增加影响缓慢。(4)通过对位于城区-郊区-农村梯度上9块湿地松人工林新鲜针叶和凋落针叶为期12个月的定位监测,结果表明：针叶P含量年均值为城区(0.94 g kg-1)和郊区(1.03 g kg-1)高于农村(0.78 g kg-1)；而P再吸收效率为城区(75%)和郊区(74%)低于农村(84%)。说明城市化影响树木P的吸收过程和利用效率。总之,城市化过程易导致城市森林土壤全P及不同功能P形态的积累,从而影响城区树木P吸收和利用,以及森林生态系统的P循环。建议控制人为干扰强度和频度,减少外源性P的输入,维持城市森林生态系统的健康。更多还原

【Abstract】 Soil phosporus (P) is not only one of the major limiting factors affecting plant growth, but also a potential source of environmental pollution. We know a little that P cycling and accumulation is influenced by the urbanization, a global problem. Soils in shrubs, Pinus massoniana, P. elliottii, conifer and broadleaf mixed, everygreen broadleaved, Phyllostachys edulis forests in the mid-subtropical region along an urban-rural gradient in Nanchang city, southern China, were analyzed for total P and P fractions using the modified Hedley P sequential fractionation method, while the seasonal variation of foliar P concentrations and resorption efficiency were studied in P. elliottii forests. The main results are as follows:(1) In general, soil total P and all P fractions concentration were highest in urban, lowest in rural under 39 sites in six forest types along an urban-rural gradient in Nanchang City, the result indicates that urbanization increase with the addition of P in urban soils.(2) Mean values of topsoil all P fractions in five typical forest successional stages(shrubs, Pinus massoniana, conifer and broadleaf mixed, everygreen broadleaved, Phyllostachys edulis forest) along an urban-rural gradient in Nanchang City were analyzed, our findings suggest that the relative abundance of HCl-P in urban forest soils (36%) was the highest among five P fractions, with NaOH-P as the dominant form in suburban (41%) and rural soils (50%); but the annual mean values of all fractions in P. elliottii forest show that NaOH-P is the dominant among five fractions in urban, suburban and rural (52%,58% and 53%, respectively). It can be seen that soil P fractions input is different among all the forests along urban-rural gradient, extraneous P input has spatial heterogeneity.(3) In five typical forest along urban-rural gradient in Nanchang City, mean values of soil all P fractions is higher in shrub and Ph. edulis forest than P. massoniana, conifer and broadleaf mixed, everygreen broadleaved forest, shrub and Ph. edulis forest are intensively anthropogenic disturbed. This means that anthropogenic disturbances can be an important factor for P accumulation, while increases in soil P pool and its availability were not significantly increased by the biological process of forest succession.(4) Leaves in 9 sites of P. elliottii forest an urban-rural gradient in Nanchang city, were analyzed for P concentration and its resorption efficiency and proficiency. The findings show mean values of leaf P concentration is higher in urban (0.94 g kg-1) and suburban (1.03 g kg-1) than rural (0.78 g kg-1), while PRE is lower in urban(75%) and suburban (74%) than rural (84%). These results suggest that urbanization affects plants P absorbability and availability.On the whole, urbanization would lead to soil total P and all P fractions accumulation which affect the cycle of P and plant absorbability in urban forest systems. Therefore, it is necessary to control anthropogenic disturbances and decrease extraneous P input in order to ensure the health of the forest ecological systems.更多还原