【作者】 张龙宁；

【导师】 贾黎明；

【作者基本信息】 北京林业大学 ， 森林培育， 2013， 硕士

【摘要】 本研究基于山东黄泛平原三倍体毛白杨纸浆林和北京沙地欧美108杨速生丰产林,采用根钻法分别对不同滴灌处理和不同水肥处理条件下两种杨树人工林林地0-30cm土层细根形态特征进行了研究,以探讨两种杨树人工林细根对不同处理的响应机制,进而从根系生长与分布角度揭示水肥管理措施促进林木生长的机制,为指导灌溉和施肥决策提供理论依据。主要研究结果及结论如下：1、基于山东黄泛平原三倍体毛白杨纸浆林的研究结果表明：垂直方向上,四种处理下的细根生物量、根长密度、表面积和体积均随土层深度的增加而显著减小,地下滴灌没有改变林木细根的垂直分布格局。地下滴灌显著提高了林地20-30cm土层细根生物量和体积。如在20-30cm土层,T2处理(以-50kPa的土壤水势为灌溉起始阈值)下的细根生物量和体积分别为0.29mg·cm-3和0.62mm3·cm-3较CK显著增加了112.31%和91.64%。地下滴灌显著降低了林地0-10cm和20-30cm土层细根比根长及10-20cm土层细根组织密度,并促使二者在各土层中分布趋于一致,以有利于各土层细根全部发挥其吸收和伸展功效。如T1处理下20-30cm土层的细根比根长和10-20cm土层的细根组织密度分别为2799.1cm·g-1和0.411g·cm-3,较CK显著减少了44.79%和17.28%。在各土层中,三种滴灌处理间各细根形态指标无显著差异。2、基于北京沙地欧美108杨速生丰产林的研究结果表明：垂直方向上,十种处理下的细根生物量、根长密度、表面积和体积均随土层深度的增加而显著减小,水肥处理没有改变林木细根的垂直分布格局。中肥(652g／株)和高肥(978g／株)条件下各水肥处理显著提高了林地三个土层细根生物量、根长密度、表面积和体积。同时两施肥水平下三个土层细根根长密度和表面积以及10-20cm和20-30cm土层细根生物量和体积均随滴灌水平的降低而显著减小。低肥(326g／株)条件下三个土层四个指标随滴灌水平的降低而无显著性变化。三种滴灌水平下三个土层细根生物量、根长密度、表面积和体积均随施肥水平的提高而显著增大。高水高肥处理(第3处理)促进细根生长的效果最明显,例如其10-20cm土层细根生物量、根长密度、表面积和体积分别为0.248mg·cm-3、0.526cm·cm-3、0.060cm2·cm-3和0.533mm3·cm-3,较CK显著增加了386.18%、176.49%、212.82%和234.53%。水肥处理对0-10cm土层细根比根长无显著影响。中水(-50kPa)和高水(-25kPa)条件下各水肥处理显著降低了林地10-20cm土层细根比根长。同时两滴灌水平下10-20cm和20-30cm土层细根比根长均随施肥水平的提高而无显著性变化。低水(-75kPa)条件下两个土层细根比根长均随施肥水平的提高而显著减小。三种滴灌水平下三个土层细根组织密度整体上均随施肥水平的提高而显著提高。三种施肥水平下10-20cm和20-30cm土层细根比根长均随滴灌水平的降低而显著增大,组织密度总体上均随滴灌水平的降低而显著降低,而0-10cm土层细根组织密度随滴灌水平的降低而无显著性变化。高水高肥处理(第3处理)促进细根比根长降低和组织密度提高的效果最明显,例如其20-30cm土层细根比根长和组织密度分别为2373.7cm·g-1和0.427g·cm-3,分别较CK显著降低和提高了45.69%和48.70%。综上,水肥管理措施能够提高林地土壤资源的有效性,从而促进林木细根的增生,进而增强林木细根对土壤水分和养分的吸收能力,这是细根形态响应不同处理的重要机制,也是水肥管理措施提高林地生产力的主要机制。同时,除低肥水平(326g/株)外,本研究中针对北京沙地欧美杨所设定的三种灌溉量及两种施肥量整体上均在适宜的范围内。因此水肥管理措施对于促进人工林林地吸收根系生长及合理分布具有重要意义,建议推广使用地下滴灌、地表滴灌和随水施肥。更多还原

【Abstract】 This study is based on triploid Populus tomentosa pulpwood on Shandong Yellow River flood plain and Populus xeuramericana fast growing and high yielding plantation at Beijing sandy land, where two field experiments were respectively conducted to investigate the fine root morphology of the two kinds of poplar plantation in0--30cm soil layers under different subsurface drip irrigation and surface drip irrigation and fertigation treatments by using soil cores method, aimed at inquiring into the mechanism how the fine root responded different treatments, revealing the mechanism how water and fertilizer management measures promoted woods growth from the angle of root distribution, and providing irrigation and fertigation decisions with theoretical basis. The main results and conclusions are as follows.1. Results based on triploid Populus tomentosa pulpwood on Shandong Yellow River flood plain showed that in the vertical direction, fine root biomass, length density, surface area and volume significantly decreased with more depth under the four treatments, subsurface drip irrigation did not change the vertical distribution pattern of fine root, subsurface drip irrigation significantly raised fine root biomass and volume in20-30cm soil layer, which was one of the main reasons why subsurface drip irrigation improved forest productivity. For example, in20～30cm soil layer, fine root biomass and volume under T2treatment were respectively0.29mg·cm-3and0.62mm3·cm-3, which were significantly112.31%and91.64%higher than CK treatment, subsurface drip irrigation significantly reduced fine specific root length in0～10cm and20～30cm soil layer and fine root tissue density in10～20cm soil layer, made both indices above in all soil layers roughly the same, in order to contribute to bringing into play the function of absorption and stretching of fine root in each soil layer. For example, under T1treatment, fine specific root length in20～30cm soil layer and fine root tissue density in10-20cm soil layer were respectively2799.1cm·g-1and0.411g·cm-3, which were significantly44.79%and17.28% lower than CK treatment. In each soil layer, the difference of each morphological index of fine root among the three subsurface drip irrigation treatments was not significant.2. Results based on Populus euramericana fast growing and high yielding plantation at Beijing sandy land showed that in the vertical direction, fine root biomass, length density, surface area and volume significantly decreased with more depth under the ten treatments, and the vertical distribution pattern of fine root has not been altered with the water and fertilizer treatments. For middle-(652g/plant) and high-(978g/plant) level of fertilizer, all treatments exerted an increase effect on fine root biomass, length density, surface area and volume. Meanwhile, fine root length density and surface area within the whole soil horizon, fine root biomass and volume in the soil layer of10-20cm and20-30cm among two levels of fertilizer decreased significantly with surface drip irrigation level. However, there was no significant change in all indices of the three soil layers for low-Ievel(326g/plant) of fertilizer. For three surface drip irrigation levels, all indices showed a significant increase with the progressive level of fertilizer. The treatment with high level of water and fertilizer(the third treatment) caused adistinct effect on the growth of fine root. The value of fine root biomass(0.248mg-cm’3), length density(0.526cm·cm-3), surface area(0.060cm2·cm-3) and volume(0.533mm3·cm-3) was386.18%,176.49%,212.82%and234.53%respectively higher relative to CK. Water and fertilizer treatments exerted no influence on fine specific root length in0～10cm soil layer. The specific root length in10-20cm soil layer significantly decreased under middle-(-50kPa) and high-(-25kPa) level of water and no significant change was found in10～20cm and20-30cm soil layer, however the specific root length in the two soil layers both declined with increasing level of fertilizer under low level(-75kPa) of water. Fine specific root length in10-20cm and20～30cm soil layer showed a significant increase with decreased surface drip irrigation level. Fine root tissue density in three soil layers appeared to increase in general with up-regulated fertilizer level but decrease in general with down-regulated water level and no significant change was found in0～10cm soil layer. An apparent decrease in specific root length and increase in root tissue density occurred with the treatment of high water and fertilizer. The fine specific root length and tissue density in20～30cm soil layer was2373.7cm·g-1and0.427g-cm-3, which was respectively45.69%lower and48.70%higher than CK.To sum up, water and fertilizer management measures can improve the effectiveness of soil resources of forest land, so as to promote fine root proliferation and enhance the absorption ability of soil water and nutrients, which is an important mechanism how the fine root morphology respond to different treatments, which is also the main mechanism how water and fertilizer management measures enhance the productivity of forest land. On the whole, except the low-level(326g/plant) of fertilizer, three kinds of irrigation level and two kinds of fertilizer level set for Beijing sand poplar were within the suitable range in this study. Therefore, water and fertilizer management measures, including subsurface drip irrigation, surface drip irrigation and fertigation, play an important role in promoting the plantation fine root growth and reasonable distribution.更多还原