【作者】 张凯；

【导师】 徐小牛；

【作者基本信息】 安徽农业大学 ， 园林植物与观赏园艺， 2007， 硕士

【摘要】 城市生态环境由于受到人为活动较大强度的干扰,其空气、水分、热量、土壤条件都具有不同于森林生态系统的特性,特别是绿地土壤的特性更是园林树木能否良好生长的重要影响因素。本研究通过选取生长于合肥市城市环境中的主要园林树木,通过分析其养分季节动态变化、养分利用效率、养分再吸收比例和氮磷比等指标以及园林树木树冠下土壤部分化学性质的研究,试图找出一些规律,从而为园林树木的养护管理提供可行的管理措施和理论依据。合肥市的城市绿地土壤受到较大的人为扰动,特别是建筑垃圾等的污染严重。土壤缺乏自然发育层次,紧实、容重高,大部数土壤偏碱性。土壤具有明显的缺氮、富磷特征。但是磷的分布极不规律,不同地点的差异极大。各个树木样株林冠下的表层0-10cm土壤,其pH（H₂O）的平均值为7.4,pH（KCl）的平均值为6.4,电导率（EC）的均值达到107μs/cm。全氮含量变动在0.07%-0.18%;全磷含量变动在86.89mg/kg-490.54mg/kg;速效磷含量在1.05 mg/kg-84.08 mg/kg。安农大校园内,重阳木落叶的全N浓度最高（1.57%）,最低的是枫香（0.57%）,全部树种的平均值为1.04%。落叶的全P含量最高的是银杏（3.29mg/g）,最低的是石楠（0.25mg/g）,全部树种的平均值为0.81mg/g。银杏的Ca含量最高（22.12mg/g）,最低的是乌桕（5.29mg/g）,全部树种的平均值为11.57mg/g。主要园林树木的氮素利用效率（NUE_N）变动范围为175.25g/g（银杏）-63.76g/g（重阳木）,全部树种的平均值为108.39 g/g。磷利用效率（NUE_p）最高的是安农大校园内石楠（4039.37g/g）,最低的是安农大校园内的银杏（303.76g/g）,全部树种的平均值为1869.19g/g。钙的利用效率(NUE_Ca)最高的是安农大校园内乌桕（189.02g/g）,最低的是银杏（45.20g/g）,全部树种的平均值为99.98g/g。紫荆鲜叶氮含量的平均值最高,达到2.91%,而石楠最低,仅为1.46%。树木鲜叶磷含量的平均值最高的是银杏,达到3.15mg/g,最低的是桂花和香樟,皆为0.95mg/g,前者为后者的3.3倍。银杏鲜叶钙含量的平均值,高达19.12mg/g,最低的是乌桕（5.19mg/g）,其含Ca量不足银杏的30%。所研究的大部分树种叶片中氮、磷含量的季节动态变化在落叶之前和生殖生长时期出现低值,而钙含量在大量落叶之前出现上升趋势。常绿阔叶树种、落叶阔叶树种和针叶树种三种不同的生活型之间无论是N、P、Ca含量还是NUE_N、NUE_p和NUE_Ca皆不存在显著差异。但是可以看出常绿树种比落叶树种具有更高的氮和磷的养分利用效率。树木的磷再吸收比例与土壤中的速效磷含量成显著的负线性相关关系R=-0.57（p=0.03）。这说明,在能被树木直接吸收的有效养分越缺乏的立地条件下,树木通过提高自身的养分再吸收比例来满足自身生长的需要能力越强。通过测定树木的N:P比发现生长在合肥市的树木表现出了不同的养分限制特征。重阳木、枫香、农大校园内香樟、合作化路乌桕、农大校园内石楠和银杏叶片的N:P比小于14,表明这些树种生长更大程度受到氮素有效性的限制作用;长江路石楠、农大校园内乌桕和紫荆叶片的N:P比介于14-16之间,表明这些树种受到氮磷元素的共同限制作用;而雪松、桂花、落羽杉、女贞和合作化路香樟叶片的N:P比大于16则反映这些树种的生长受磷素的限制更为强烈。所有树种的NUE_N和NUE_p线性相关性极显著R=0.82（p=0.0001）,说明对于所研究的树木来说在提高氮利用效率的同时,对磷的利用效率也相应的提高。更多还原

【Abstract】 The air,moisture,heat quantity and soil in the urban area were significantly different from those in forest ecosystem because of long-term human disturbances.The characteristics of urban soils were the important controls determining the growth of urban trees.Nutrient seasonal dynamics,nutrient use efficiency,nutrient resorption and N:P ratio of major urban trees in Hefei and some soil chemical properties of different urban green-lands were studied in order to find some orderlinesses which were useful for urban tree management.The soils under urban green-lands in Hefei were badly disturbed by human activities, particularly the pollution from architectural garbage.Urban soil could trend to be alkaline. Urban soils were poor in N but rich in P which distribution was irregular.The mean pH （H₂O）in 0-10 cm soil was 7.4,and pH（KCl）was 6.4.The mean EC in 0-10 cm soil was 107μs/cm.Total nitrogen concentrations varied from 0.07%to 0.18%.Total phosphorus concentrations varied from 86.89 mg/kg to 490.54 mg/kg and available phosphorus varied from 1.05 mg/kg to 84.08 mg/kg.Bischofia polycarpa in the campus had the highest nitrogen concentration（1.57%）in leaf litter and Liquidamba formosana the lowest（0.57%）.The mean concentration of all tree species was 1.04%.The highest phosphorus concentration was found in leaf litter of Ginkgo biloba in the campus（3.29 mg/g）and the lowest in Photinia serrulata（0.25 mg/g）. The mean P concentration of all tree species was 0.81 mg/g.The highest calcium concentration in leaf litter was Ginkgo biloba in the campus（22.12 mg/g）and the lowest in Sapium sebiferum（5.29 mg/g）.The mean concentration of all tree species was 11.57 mg/g.The nitrogen use efficiency（NUE_N）in leaf litter was the highest for Liquidamba formosana in the campus（175.25g/g）while Bischofia polycarpa the lowest（63.76 g/g）. The mean value of NUE_N of all tree species was 108.39 g/g.The phosphorus use efficiency （NUE_p）was the highest in leaf litter of Photinia serrulata in the campus（4039.37 g/g）and the lowest was Ginkgo biloba（303.76 g/g）.The mean NUE_p was 1869.19 g/g for all tree species.The calcium use efficiency(NUE_Ca)in leaf litter was Sapium sebiferum（189.02 g/g）and the lowest was Ginkgo biloba（45.20g/g）.The mean NUE_Cawas 99.98 g/g for all tree species. The mean nitrogen concentration in fresh foliage of Cercis chinensis in the campus was 2.91%,which was 2 fold as high as in Photinia serrulata（1.46%）.The highest mean phosphorus concentration was found in the foliage of Ginkgo biloba（3.15 mg/g）,while the lowest in Osmanthuum fragrans and Cinnamomum camphora（0.95 mg/g）.The mean concentration of calcium in foliage of Ginkgo biloba was 19.12 mg/g which was 2.68 times greater than in Sapiurn sebiferum（5.19 mg/g）.The lower concentrations of nitrogen and phosphorus in the foliage appeared in the period of peak leaf fall and procreative stage.Calcium concentration was likely to increase before the peak fall.No significant differences were found in both N,P,Ca concentrations and NUE_N,NUE_p, NUE_Cafor different types,evergreen broad-leaved,deciduous broad-leaved and coniferous tree species.Evergreen broad-leaved trees had higher NUE_N and NUE_P than deciduous broad-leaved trees.Significantly negative correlation was found between P resorption and available P in urban soil R=-0.57（p=0.03）.It demonstrates that the trees growing on the site with lower P availability like to increase P resorption.Different characteristics of nutrient limitation were found in urban trees by determination of N:P ratio.The N:P ratios lower than 14 were found in Bischofia polycarpa,Liquidamba formosana,Cinnamomum camphora,Photinia serrulata and Ginkgo biloba in the campus,and Sapium sebiferum in Hezuohua Road,indicating an existence of nitrogen limitation.Photinia serrulata in Changjiang Road,and Sapium sebiferum and Cercis chinensis in the campus had a N:P ratio between 14 to 16,indicating limitation of both nitrogen and phosphorus.However,The N:P ratios in Cedrus deodara, Osmanthuum fragrans,Taxodium distichum,Ligustrum lucidum and Cinnamomum camphora in Hezuohua Road were greater than 16,which suggests that those trees were likely limited by phosphorus.Significantly positive correlations were found between NUE_N and NUE_P R =0.82（p= 0.0001）.This suggests that there exists an interaction between N and P in the urban trees.更多还原