中亚热带不同森林更新方式生态酶化学计量特征

Patterns of eco-enzymatic stoichiometry in mid-subtropical forest regeneration

了解土壤生态化学计量特征对预测不同生态系统养分变化、功能以及植物生产力具有重要意义。森林更新是维持中亚热带森林生态系统可持续发展的重要手段。选取福建省三明市陈大林业采育场3种不同森林更新方式进行研究,包括米槠次生林(SF)、米槠人工促进天然更新林(AR)和杉木人工林(CF),测定其土壤理化性质及土壤3种酶,计算酶化学计量。结果显示:1) AR的土壤总氮、全磷、铵态氮含量以及含水量最高(P<0.05),土壤有效磷的含量则是CF最高(P<0.05); 2)生态酶化学计量结果表明AR的土壤微生物处于氮限制状态,CF的土壤微生物处于磷限制状态; 3)冗余分析表明,土壤含水量和铵态氮是驱动不同森林更新方式土壤生态酶化学计量变异的重要环境因子。研究表明,人促更新方式更有利于土壤有效氮的积累,而人工林则有利于土壤有效磷积累,这可能与造林树种有关。土壤生态酶化学计量更易受到土壤含水量以及有效性养分的驱动,而与土壤化学计量未呈现良好的耦合性。

Understanding the characteristics of soil ecological stoichiometry is important for predicting nutrient changes, plant productivity, and ecosystem functions in different ecosystems. Forest regeneration is an important approach to accomplish sustainable development of mid-subtropical forest ecosystems. Therefore, in this thesis, three contrasting ways of forest regeneration were selected for study in the Chenda state-owned forestry farm in Fujian; namely, Castanopsis carlesii forest （SF）, human-assisted naturally regenerated Castanopsis carlesii forest （AR）, and Cunninghamia lanceolata plantation （CF）. Additionally, different physical and chemical soil properties were examined, along with three types of soil enzymes, and eco-enzymatic stoichiometry was calculated. Our results revealed the following： 1 ） the soil contents of total nitrogen, total phosphorus, ammonium nitrogen, and moisture were the most significant in the human-assisted naturally regenerated Castanopsis carlesii forest （P 〈 0. 05 ）, while soil content of available phosphorus was the highest in the Cunninghamia lanceolata plantation （P〈 0.05 ） ; 2） according to the eco-enzymatic stoichiometry calculation, the state of soil microorganisms were restricted by nitrogen availability in the human-assisted naturally regenerated Castanopsis carlesii forest, and by phosphorus availability in the Cunninghamia lanceolata plantation ; 3） as redundancy analysis showed, the content of soil moisture and ammonium nitrogen are important environmental factors that influence the eco-enzymatic stoichiometry of different forest regeneration methods. Generally, human-assisted natural regeneration is more beneficial to soil mineral nitrogen accumulation, while artificial forest regeneration is conducive to accumulation of available phosphorus in the soil, which may be related to the tree species selected for afforestation. Soil eco-enzymatic stoichiometry is more likely to be driven by soil moisture content and nutrient availability than by soil stoichiometry.