| 摘要: |
| 【目的】研究添加外源养分对麻栎细根生长特征、形态特征和养分特征的影响，探讨细根在不同富养斑块的觅养特征，为研究细根养分捕获策略提供理论支撑。【方法】以林龄约30年的麻栎为研究对象，采用原位根系生长袋法，设置对照（CK）、氮添加（N）、磷添加（P）、多养分添加（NPK）、凋落物添加（F）共5个处理，探究细根生长特征（细根生物量、总根长）和形态特征（平均直径、比根长、组织密度、比表面积、分枝比、分枝强度）以及细根中N、P含量对养分添加的响应规律。【结果】（1）与CK相比，NPK处理麻栎1~3级细根的总根长及生物量均显著增加(P<0.05)；而N处理总根长和生物量均表现出降低趋势，但差异并未达到显著水平（P>0.05）。（2）不同外源养分对麻栎细根形态特征的影响并不一致。与CK相比，P、NPK、F处理总体使麻栎细根直径减小，而N处理使3级根直径显著增加（P<0.05），细根的组织密度、比根长和比表面积对4种养分添加处理响应并不敏感。与CK相比，P、NPK和F处理对细根分枝比和分枝强度无显著影响（P>0.05），但N处理使2~3级细根的分枝比和分枝强度显著增加（P<0.05）。（3）N、P、NPK、F 4个处理细根的N含量均高于CK，其中N、NPK处理与CK之间均存在显著差异（P<0.05），较CK增幅分别为102.3%和77.0%；N及F处理细根P含量与CK之间无显著差异（P>0.05），但NPK和P处理细根的P含量均较CK显著增加（P<0.05），其中以NPK处理最高，较CK的增幅为128.8%。【结论】同时增加土壤N、P养分时，麻栎通过增殖根长和细根生物量来获取更多的养分，而将N、P肥单独作为外源养分添加时，麻栎则通过改变细根形态特征来提高对土壤养分的吸收能力，添加凋落物对麻栎细根生长形态特征无明显影响，可知麻栎对不同类型外源养分具有不同的吸收策略。 |
| 关键词: 麻栎 细根生长 外源养分 根系形态特征 森林生态 |
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| 基金项目:国家自然科学基金项目（31270489,31700555） |
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| Effects of different exogenous nutrients on fine roots growth,morphology and N and P contents of Quercus acutissima |
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HAO Qianwei,YU Shuiqiang,CAO Yuting,et al
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| Abstract: |
| 【Objective】To provide theoretical support for understanding fine roots nutrients capture strategies,the effects of different exogenous nutrients on growth, morphological and nutrient characteristics of Quercus acutissima fine roots were studied and the foraging characteristics of fine roots in different nutrient rich patches were discussed.【Method】Q. acutissima with a stand age of about 30 years was planted using in situ root bag method with five treatments of control (CK),nitrogen additions (N),phosphorus additions (P),multi nutrient additions (NPK) and litter additions (F).Fine roots growth indicators (fine root biomass and total root length),morphological indicators (average diameter,specific root length,root tissue density,specific surface area,branching ratio and branching intensity) as well as the contents of N and P in fine roots were determined.【Result】(1) Compared with CK,NPK treatments significantly increased the total root length and biomass of levels 1－3 Q. acutissima fine roots (P<0.05).The total root length and biomass of N treatment showed a decreasing trend without significant differences (P>0.05).(2) Effects of different nutrient addition treatments on morphological characteristics of Q. acutissima fine roots were not consistent.Compared with the CK,treatments of P,NPK and F reduced the average diameter of fine roots in general,while N treatments significantly increased the average diameter of level 3 fine roots (P<0.05).The root tissue density,specific root length and specific surface area of fine roots were not sensitive to the nutrient addition treatments.Compared with CK,P,NPK and F treatments did not significantly affect the branching ratio and branching intensity of fine roots (P>0.05),while N treatment significantly increased the branching ratio and branching intensity of levels 2－3 fine roots (P<0.05).(3)The N contents in fine roots of N,P,NPK and F treatments were higher than those of the CK.There were significant differences between N and NPK treatments and CK,with increases of 102.3% and 77.0%,respectively.There was no significant difference in P contents in fine roots between N and F treatments and CK (P>0.05).The NPK and P treatments significantly increased P contents (P<0.05),with the highest increase of 128.8% in the NPK treatment compared with CK.【Conclusion】The fine roots of Q. acutissima invested more root length and biomass to obtain nutrients when soil N and P availability were increased at the same time.When N fertilizer and P fertilizer were added separately as exogenous nutrients,the fine roots improved the absorption capacity of soil nutrients by changing root morphological characteristics.Adding litters had no significant effect on Q. acutissima fine root growth and morphological characteristics.In conclusion,Q. acutissima had different nutrient absorption strategies for different types of nutrient additions. |
| Key words: Quercus acutissima fine root growth exogenous nutrients root morphological characteristics forest ecology |
