雷竹氮素利用特性及其林地覆盖效应

发布时间：2018-09-03 12:09

【摘要】：雷竹(Phyllostachys violascens)隶属于禾本科竹亚科刚竹属,具有出笋早、笋期长、成林快、品质优良等特点,是一种优良的笋用竹种,广泛栽植于浙江、江苏、江西等地。上世纪90年代以来,雷竹主产区推广了大量施肥和冬季有机材料覆盖相结合的竹笋早出技术,明显提前了雷竹的出笋日期和提高了竹笋产量,带来显著的竹林经营经济。但不合理的施肥措施以及长期持续的林地覆盖导致雷竹林土壤退化,严重不利于竹林经营的可持续发展。为揭示雷竹的氮素养分利用特性及其林地覆盖效应,为雷竹林氮素科学补充提供理论参考,开展了氮素形态及配比对雷竹生理代谢及主要养分积累、覆盖经营对雷竹林土壤氮素赋存形态及硝化和反硝化作用、覆盖措施对雷竹林土壤硝化和反硝化作用及雷竹氮素传输的影响等研究。主要研究结果如下:1氮素形态及配比对雷竹光合特性及主要氮代谢酶的影响通过设置NO_3~--N/NH_4~+-N比例为1:0、2:1、1:1、1:2、0:1的5个控制实验处理,研究表明同一氮素含量供应水平下,随着氮素供应中NH_4~+-N比例的增加,雷竹叶片的Chla、Chlb、Car含量和P_n、G_s、T_r均呈先升高后降低的变化趋势,硝铵比1:2处理明显高于其他处理,而Ci出现相反的变化规律,在硝铵比1:2处理时明显低于其他处理;NR、GS活性随NH_4~+-N比例的增加也呈先升高后降低的变化趋势,NH_4~+-N/NO_3~--N混合营养的处理间则无显著差异,但高于单一氮素形态的营养处理。综合分析认为雷竹为弱喜铵植物,硝铵混合营养能促进雷竹光合作用和氮同化能力的提高。2氮素形态及配比对雷竹抗氧化系统的影响同一氮素含量供应水平下,相同的硝铵比例处理下,雷竹叶片的丙二醛、可溶性蛋白质含量和抗氧化酶活性均高于细根,即相比于细根,雷竹叶片抗氧化系统对氮素营养的响应更加敏感。混合氮素形态营养供应的雷竹叶片和细根的丙二醛含量较单一氮素形态供应低,而且可溶性蛋白质含量和抗氧化酶活性均能维持在较高水平,说明混合氮素形态营养处理下雷竹受到的膜脂过氧化程度较低,抗逆性较强。同一氮素含量供应水平下,不同形态氮素营养处理对雷竹叶片和细根的C含量没有显著影响,但显著影响N、P元素含量和C、N、P化学计量比及其异速生长关系。随着氮素供应中NH_4~+-N比例的增加,雷竹叶片和细根的C含量变化不明显,N、P含量均呈倒“V”型变化,在硝铵比为1:1、1:2时显著高于其他处理;叶片和细根的C:N、C:P、N:P总体上呈降低趋势,表明叶片和细根的生长速率提高;叶片和细根N与C、N与P的Ⅱ类回归斜率也呈先降低后升高的倒“V”型变化,且硝铵比为1:1、1:2时斜率显著增大,表明在相同N增量条件下,雷竹叶片和细根的C、P有更多的积累量。4覆盖经营年限对雷竹林土壤氮素赋存形态的影响通过对覆盖1年、3年、5年和不覆盖雷竹林土壤的NH_4~+-N、NO_3~--N含量及硝铵比研究表明,在时间尺度上,雷竹林土壤NH_4~+-N、NO_3~--N含量及硝铵比存在明显的季节性差异,其中土壤NH_4~+-N、NO_3~--N含量随着一年中时间的推移先降低后升高,土壤硝铵比则相反,随时间的推移呈先升高后降低的趋势。在空间尺度上,随着雷竹林土层深度的增加,雷竹林土壤NH_4~+-N含量呈降低趋势,具表聚性现象;NO_3~--N含量覆盖1年雷竹林表现为底层积聚,覆盖3年、5年雷竹林则具表聚性现象。与不覆盖雷竹林相比,覆盖1年雷竹林土壤硝铵比增大,NO_3~--N是土壤无机氮主要存在形式,而覆盖3年、5年雷竹林土壤NH_4~+-N比重增加,形成以铵态氮为主要无机态氮的“富营养生境”。5覆盖经营年限对雷竹林土壤硝化和反硝化作用的影响通过对覆盖1年、3年、5年和不覆盖雷竹林土壤硝化速率和反硝化速率的研究表明,覆盖经营年限和季节具有交互作用,均对雷竹林土壤硝化速率有显著影响。随着覆盖年限延长,各实验雷竹林不同季节的土壤硝化速率呈逐渐降低的趋势;雷竹林土壤硝化速率与氮源的相关性关系弱化,但与土壤有机质及其他物理性状因子的相关性关系呈增强趋势。不同覆盖经营年限雷竹林不同季节的土壤反硝化速率总体上变化并不明显,仅7月和9月覆盖5年雷竹林土壤反硝化速率显著高于其他覆盖经营年限雷竹林,说明长期覆盖经营会提高雷竹林土壤反硝化作用,造成林地氮素以氧化亚氮等气体形式损失。3氮素形态及配比对雷竹养分化学计量特征的影响6覆盖措施对雷竹林土壤硝化和反硝化作用的影响覆盖措施和覆盖时间对雷竹林土壤硝化和反硝化作用均有显著影响,而且两者存在明显的交互作用;覆盖能促进雷竹林土壤反硝化作用,但长时间覆盖会抑制雷竹林土壤硝化作用;覆盖总体上会降低雷竹林土壤硝化速率、反硝化速率与土壤理化性质的相关性程度,土壤环境影响因子具有多样和复杂的变化趋势;影响覆盖雷竹林土壤硝化速率的主要环境因子是土壤含水量、p H值、NH_4~+-N含量和总孔隙度,影响土壤反硝化速率的主要环境因子是土壤含水量、p H值和总孔隙度。7覆盖措施对雷竹氮素传输的影响覆盖措施能促进雷竹自身对氮素养分的吸收利用,一定程度上减少了氮素养分的传输,也即雷竹林养分生理整合功能减弱。实验雷竹林土壤氮素养分丰盈的背景及竹林强度经营导致的地下鞭系统克隆片段化可能对养分生理整合功能会产生明显的影响。
[Abstract]:Phyllostachys violascens belongs to the subfamily Phyllostachys of Gramineae. It has the characteristics of early shooting, long shooting period, fast planting and good quality. It is a good shoot bamboo species, widely planted in Zhejiang, Jiangsu, Jiangxi and other places. Since 1990s, a large number of fertilization and winter organic material mulching have been popularized in the main producing areas of Phyllostachys. The early emergence of bamboo shoots obviously advanced the date of bamboo shoot emergence and increased the yield of bamboo shoots, which brought about remarkable economic benefits for bamboo forest management. The effects of Mulching on soil nitrogen forms, nitrification and denitrification, and the effects of Mulching on soil nitrification and denitrification and nitrogen transport were studied. The main results are as follows: 1. The effects of nitrogen forms and ratios on Photosynthetic Characteristics and main nitrogen metabolic enzymes of Phyllostachys praecox were studied by five controlled experimental treatments with the ratio of NO_3~--N/NH_4~+-N of 1:0,2:1,1:1,1:2,0:1. The results showed that under the same nitrogen supply level, with the increase of the ratio of NH_4~+-N in the leaf of Phyllostachys praecox. The content of la, Chlb, Car and P_n, G_s and T_r increased first and then decreased. The ratio of ammonium nitrate to ammonium nitrate 1:2 was significantly higher than that of other treatments, but Ci showed the opposite change rule, which was obviously lower than that of other treatments when the ratio of ammonium nitrate to ammonium nitrate was 1:2. The activity of NR and GS increased first and then decreased with the ratio of NH_4~+-N/NO_3~--N. There was no significant difference among the treatments, but it was higher than the nutrient treatments with a single nitrogen form. Comprehensive analysis showed that Phyllostachys thunbergii was a weak ammonium-like plant. Mixed nutrition of ammonium nitrate could promote photosynthesis and nitrogen assimilation of Phyllostachys thunbergii. 2 Nitrogen forms and ratios affected the antioxidant system of Phyllostachys thunbergii at the same nitrogen supply level. The MDA content, soluble protein content and antioxidant enzyme activity in leaves of Phyllostachys praecox were higher than those in fine roots, that is to say, the antioxidant system in leaves of Phyllostachys praecox was more sensitive to nitrogen nutrition than that in fine roots. Both soluble protein content and antioxidant enzyme activity could be maintained at a higher level, indicating that the membrane lipid peroxidation and stress resistance of Phyllostachys praecox were lower under mixed nitrogen form nutrition treatment. The contents of N, P and C, N, P in leaves and roots of Phyllostachys thunbergii showed an inverted V-shaped change with the increase of NH_4~+-N ratio in nitrogen supply, which was significantly higher than that of other treatments when the ratio of nitrate to ammonium was 1:1, 1:2, and the contents of C: N, C: P, N: P in leaves and roots decreased as a whole. The results showed that the growth rate of leaves and fine roots increased, and the regression slopes of N and C, N and P in leaves and fine roots decreased first and then increased, and the slopes increased significantly when the ratio of ammonium nitrate to ammonium nitrate was 1:1,1:2, indicating that under the same N increment conditions, the accumulation of C and P in leaves and fine roots increased. Effects of nitrogen forms on NH_4~+-N, NO_3~-N contents and NH_4~+-N, NO_3~-N ratios in soils covered with 1, 3, 5 and uncovered thunder bamboo forests were studied. The results showed that there were significant seasonal differences in NH_4~+-N, NO_3~-N contents and NH_4~+-N ratios in the soil of thunder bamboo forests on the time scale. On the spatial scale, with the increase of soil depth, the soil NH_4~ + - N content in the Phyllostachys praecox forest showed a decreasing trend and a surface accumulation phenomenon; the soil NH_3~ - N content in the Phyllostachys praecox forest covered for one year showed a bottom accumulation, covering for three years, covering for five years showed a bottom accumulation. Compared with non-mulched Phyllostachys praecox forest, the ratio of soil ammonium nitrate to ammonium nitrate increased in one year mulched Phyllostachys praecox forest, and NO_3~--N was the main form of soil inorganic nitrogen, while the proportion of soil NH_4~ + - N increased in three and five years mulched Phyllostachys praecox forest, forming "eutrophic habitat" in which ammonium nitrogen was the main inorganic nitrogen. Nitrification and denitrification rates of soils covered with 1,3,5-year mulch and uncovered bamboo forests were studied. The results showed that mulching years and seasons had interactive effects on soil nitrification rates of bamboo forests. The correlation between soil nitrification rate and nitrogen source was weakened, but the correlation with soil organic matter and other physical properties was strengthened. The soil denitrification rate did not change significantly in different seasons under different mulching years, except in July and September, when the soil was covered for 5 years. Soil denitrification rate was significantly higher than that of other mulching years of Phyllostachys thunbergii forest, indicating that long-term mulching would increase soil denitrification, resulting in nitrogen loss in the form of nitrogen oxides and other gases. 3 Nitrogen forms and ratios of Phyllostachys thunbergii nutrient differentiation stoichiometric characteristics of the impact of 6 Mulching Measures on soil nitrification and denitrification of Phyllostachys thunbergii forest The effects of mulching measures and mulching time on soil nitrification and denitrification of Phyllostachys praecox plantation were significant, and there was a significant interaction between them; mulching could promote soil denitrification of Phyllostachys praecox plantation, but long-term mulching could inhibit soil nitrification of Phyllostachys praecox plantation; mulching could reduce soil nitrification rate and denitrification of Phyllostachys praecox plantation The correlation degree between soil physical and chemical properties and soil environmental impact factors are various and complex. The main environmental factors affecting soil nitrification rate of mulched Phyllostachys praecox forest are soil water content, P H value, NH_4~+-N content and total porosity. The main environmental factors affecting soil denitrification rate are soil water content, P H value. Effects of Mulching Measures on nitrogen transport in Phyllostachys praecox Fragmentation of the flagellum system may have a significant effect on the physiological integration function of nutrients.
【学位授予单位】：中国林业科学研究院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S795

【相似文献】