| 摘要: |
| 【目的】 研究陕西关中地区一些常见树种落叶前的养分回流规律，为养分循环利用机制及树木施肥提供理论依据。【方法】 选择6个坡地造林树种、5个平地果园树种和10个园林绿化树种的生活叶和凋落叶，称其干质量，对其N、P、K养分含量进行大样本采样测定，计算树叶干质量减少率Rw和养分回流（顺流）率Rn。【结果】 （1）具有高含N（>10.0 g/kg）落叶的树种有刺槐、杜仲、桃树、核桃、樱桃、杏树、苹果、苦皮藤、香果树、鹅耳枥和梾木，具有高含P（>1.0 g/kg）落叶的树种有泡桐、元宝枫、樱桃、核桃、桃树、香果树和苦皮藤，具有高含K（>5.0 g/kg）落叶的树种有泡桐、杜仲、桃树、杏树、苹果和鹅耳枥。（2）在落叶前，所有选测树种的树叶干质量均发生了不同程度减少，其中，核桃和苦皮藤树叶干质量发生强度减少（Rw>40%），香果树树叶干质量发生次强度减少（Rw=30%～40%），泡桐、樱桃、苹果和丁香树叶干质量发生中度减少（Rw=20%～30%）。（3）在落叶前，所有树种的树叶均发生了N、P回流，其中，发生次强度N回流（Rn=60%～80%）的树种有：油松、刺槐、侧柏、苹果、荷花玉兰、苦皮藤、女贞和香果树；发生次强度P回流（Rn=60%～80%）的树种有：刺槐、油松、侧柏、杏树、苹果、苦皮藤、女贞和丁香。（4）在落叶前，大部分树种的树叶发生了K回流，其中，发生强度K回流（Rn>80%）的树种有：刺槐、油松、侧柏、银杏和荷花玉兰；发生次强度K回流（Rn=60%～80%）的树种有：女贞、苦皮藤和香果树；少部分树种却发生了K顺流（Rn＜0），其中，发生次强度（ARn=60%～80%，指Rn的绝对值，下同）和中度（ARn=40%～60%）K顺流的树种分别为丁香和核桃，发生弱度（ARn=20%～40%）和微弱（ARn＜20%）K顺流的树种分别为杏树和紫玉兰。【结论】 不同树种的不同养分元素回流规律存在很大差异，在树体内K是一个较N、P 更为活跃、流动性更大的养分元素。 |
| 关键词: 陕西关中地区 林木养分 生物化学循环 养分回流 |
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| 基金项目:陕西省自然科学基础研究计划项目（2009JM3014）；国家自然科学基金项目(30471376)；西北农林科技大学人才计划项目(2005) |
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| Nutrient（N，P，K）back flowing before leaves withering in many common tree species in Guanzhong area of Shaanxi |
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XUE Shao ping YAN Xiao li ZHU Rui xiang YAO Wan sheng Han Si ming
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| Abstract: |
| 【Objective】 Study was done on nutrient back flowing before leaves withering of many common tree species in Guanzhong area of Shaanxi to provide theoretic basis for revealing the principle of trees to self-conserve,biochemical recycle and reuse nutrients and directing fertilization.【Method】 The dry weight and nutrient contents of tree leaves before or after its withering were determined with big samples for 6 tree species of slope forest,5 tree species of orchard and 10 tree species of garden greening respectively.【Result】 （1）The species with a high N content（>10.0 g/kg） in fallen leaves included Robinia pseudoacacia,Cortex eucommiae,Prunus persica,Juglans regia,Prunus speciescherry,Prunus armeniaca,Malus pumila,Celastrus angulatus,Emmenopterys henryi,Carpinus fargesiana and Cornus macrophylla.The trees with high P content（>1.0 g/kg） in fallen leaves included Paulownia fortunei,Acer truncatum,Prunus speciescherry,Juglans regia,Prunus persica,Emmenopterys henryiand Celastrus angulatus.The plants with high K content（>5.0 g/kg） in fallen leaves included Paulownia fortunei,Cortex eucommiae,Prunus persica,Prunus armeniaca,Malus pumila and Carpinus fargesiana.（2）During the process of leaves withering,the leaves dry weight of total tree species decreased with different extents,that is,for leaves dry weight Juglans regiaand Celastrus angulatusdecreased strongly（Rw>40%），Emmenopterys henryi was the next one（Rw=30%-40%）,Paulownia fortunei,Prunus speciescherry,Malus pumila and Eugenia caryophyllata were the last ones (Rw=20%-30%）.（3） Before leaves withering,N and P in leaves of all the tree species back flowed.Among them,trees with 60%-80% of back flowed N in leaves included Pinus tabulaeformis,Robinia pseudoacacia,Platycladus orientalis,Malus pumila,Magnolia denudate,Celastrus angulatus,Ligustrum lucidumand Emmenopterys henryi.The tree species with 60%-80% of back flowed P in leaves included Robinia pseudoacacia,Pinus tabulaeformis,Platycladus orientalis,Prunus armeniaca,Malus pumila,Celastrus angulatus,Ligustrum lucidumand Eugenia caryophyllata.（4） K in leaves of most species back flowed before leaf withering,in which,the tree species whose K in leaves back flowed most strongly（Rn>80%）included Robinia pseudoacacia,Pinus tabulaeformis,Platycladus orientalis,Ginkgo bilobaand Magnolia denudate.The tree species whose K in leaves back flowed strongly（Rn=60%-80%）included Ligustrum lucidum,Celastrus angulatusand Emmenopterys henryi.In reverse,K in leaves of a few tree species down flowed before its withering（Rn＜0）,in which,the tree species whose K in leaves down flowed strongly（ARn=60%-80%,ARn means absolute value of Rn,the same with following）and moderately（ARn=40%-60%） were Eugenia caryophyllataand Juglans regia,respectively.The tree species whose K in leaves down flowed slightly（ARn=20%-40%） and less slightly （ARn＜20%） were Prunus armeniacaand Magnolia liliflora,respectively.【Conclusion】 There is great difference of nutrient back following between different tree species.K is a more active and fluxional nutrient than N and P in trees.So,the effects of fertilizing vary with tree species and nutrients. |
| Key words: Guanzhong area of Shaanxi trees nutrient biochemical recycling nutrient back-flowing |
