尾巨桉萌芽林与混交改造林径流水质变化特征

Characteristics of runoff water quality change in the sprout forest and mixed reconstruction forest of Eucalyptus urophylla

【目的】探讨桉树纯林及桉树混交林坡面径流水质变化特征,揭示水质变化的客观规律,为正确回答和解决桉树人工林水质问题,实现桉树人工林可持续发展提供重要科学依据。【方法】以桉树纯林、桉树×灰木莲混交林(带状混交、行间混交、株间混交)、灰木莲纯林为研究对象,选取对森林水质有关键影响作用的因子,采用连续监测与实验室分析相结合的方法,对比不同栽培模式条件下径流水质变化差异。【结果】1)试验样地坡面径流水pH值、COD、BOD5均达到我国农田灌溉水质标准(GB 5084—2021)对pH值(5.5~8.5)、COD(<150.00 mg·L^(-1))、BOD5(<60.00 mg·L^(-1))浓度的要求;2)桉树纯林坡面径流水中单宁含量(7.77 mg·L^(-1))显著高于其他样地,达到空白对照样地(1.22 mg·L^(-1))的6.4倍,桉树×灰木莲混交后可以有效降低坡面径流水中单宁含量,其中桉树×灰木莲行间混交模式效果最明显;3)桉树和灰木莲纯林坡面径流水中腐殖酸含量均高于混交林,其中桉树×灰木莲带状混交模式更有利于其坡面径流水中腐殖酸含量的降低。【结论】桉树混交模式的营建在保证坡面径流水质主要指标达标的同时能有效降低坡面径流水中单宁及腐殖酸含量,桉树混交栽培模式进一步缓解了桉树纯林对土壤酸碱性及微生物的影响。

【Objective】To explore the change characteristics of runoff quality on the slope of pure forest and mingled forest of Eucalyptus,reveal the objective laws of water quality changes,and provide an important scientific basis for correctly answering and solving the water quality problem of Eucalyptus plantation and realizing the sustainable development of Eucalyptus plantation.【Method】Eucalyptus,Eucalyptus×Manglietia glauce(ribbon mixing,interrow mixing and interplant mixing)and M.glauce were selected as the research objects,and the key factors affecting forest water quality were selected.The changes of runoff quality under different cultivation modes were compared by using the method continuous monitoring and laboratory analysis.【Result】1)The pH,COD,and BOD5 of the runoff on the slope of each experimental plot met the requirements of standard for irrigation water quality(GB 5084-2021)for pH(5.5-8.5),COD(<150.00 mg·L^(-1))and BOD5(<60.00 mg·L^(-1))concentrations.2)The tannin content(7.77 mg·L^(-1))in the runoff of Eucalyptus plantation slope was significantly higher than that of other plots,which was 6.4 times higher than the blank control plot(1.22 mg·L^(-1)).Eucalyptus×M.glauce can effectively reduce the tannin content in slope runoff,with interrow mixing mode is the most effective.3)The humic acid content in the slope runoff of Eucalyptus plantation and M.glauce were higher than that of mixed forests,meanwhile Eucalyptus plantation and M.glauce ribbon mixing mode was more conducive to the reduction of humic acid content in the slope runoff.【Conclusion】Eucalyptus mixed planting mode can effectively reduce the content of tannins and humic acids in slope runoff while ensuring the main indicators of water quality meet the standards,and alleviate its further impact on soil acidity,alkalinity and microorganisms.