林地覆盖经营对雷竹叶片主要养分特征的影响

为揭示林地覆盖经营雷竹Phyllostachys violascens林退化机理,给退化雷竹林恢复提供参考,探讨了短期覆盖(覆盖1 a),休养式覆盖(覆盖3 a休养3 a),长期覆盖(覆盖6 a)和不覆盖雷竹林2年生和3年生立竹叶片主要养分含量及其相关性和养分再吸收的变化规律。结果表明:相同覆盖经营年限雷竹林立竹成熟叶主要养分含量和再吸收率总体上2年生立竹大于3年生立竹。林地覆盖经营对雷竹2年生和3年生立竹成熟叶、老化叶氮、磷、钾和镁质量分数均有较明显的影响(P<0.05),其中,短期和休养式覆盖经营雷竹林成熟叶氮、磷和钾质量分数升高,长期覆盖经营雷竹林成熟叶氮和钾质量分数显著下降(P<0.05),磷质量分数显著升高(P<0.05),而成熟叶镁质量分数不同覆盖年限雷竹林均有下降。短期和休养式覆盖经营能提高立竹叶片主要养分再吸收率(P<0.05),增强立竹叶片养分元素间相关性,而长期覆盖经营虽显著提高了叶片氮和磷再吸收率,但降低了钾和镁再吸收率,并使立竹叶片养分元素间相关性明显减弱。研究表明:林地覆盖经营不仅影响雷竹林立竹叶片的养分状况,而且会干扰叶片养分的再吸收性。长期林地覆盖经营对雷竹生长发育会产生负面影响,生产中应采用休养式林地覆盖经营方式。

Leaf nutrient degradation due to mulching in a Phyllostachys violascens stand

To determine degradation in a Phyllostachys violascens stand due to mulching and to provide theoretical guidance for regeneration of degraded bamboo stands. Treatments included stands with short-term （1 year）, respite （mulched 3 years and rested 3 years）, long-term mulching （6 years）, and with no mulching （ck） as a control. With 3 plots of each treatments, plots were chosen that had similar slope, aspect, area（each plot  not less than 0.1 hectares） etc. Bamboo leaves of 2-and 3-year-old culms was collected in each plots，and a total of 18 replications of each age bamboo. The leaves nutrients concent of bamboo were determined, and the significant analysis of nutrients concent, resorption efficiency along with leaf content, the correlation analysis of major leaf nutrients in 2- and 3-year-old culms with different mulch management durations was done with Office-Excel software and SPSS 10.0 software（P = 0.05）. Results showed that nutrient content of mature leaves and their resorption efficiency for 2-year-old culms was significantly higher（P＜0.05） than that of 3-year-old culms. Compared with the control, N, P, and K increased significantly（P＜0.05） in short-term and respite mulched stands; N declined significantly （P＜0.05）, but P was in adverse（P＜0.05） in long-term mulched stands; and Mg decreased significantly（P＜0.05） in all stands. Nutrient resorption efficiency and the correlation between different nutrient elements both increased significantly （P＜0.05） in short-term and respite mulched stands; whereas in long-term mulched stands, apart from an significant increase（P＜0.05） of N and P resorption efficiency, both declined significantly （P＜0.05）. Thus, mulch management affected nutrient content and resorption efficiency of leaves with long-term mulching causing negative impacts on growth and development of Ph. violascens stands; respite mulched treatments should be adopted in production.［Ch, 1 fig. 3 tab. 29 ref.］