不同集约栽培年限下雷竹林土壤化学性质与生理毒性铝的分布

Chemical properties and distribution of phytotoxic Al species in intensively cultivated soils of Phyllostachys praecox stands

通过研究集约经营条件下,雷竹Phyllostachys praecox栽培时间对土壤化学性质,尤其是对土壤酸度和土壤生理毒性铝形态分布的影响,为评估酸化雷竹林地土壤铝毒胁迫强度及其在雷竹林土壤退化过程中的贡献提供理论支持。设对照(水稻田和红豆杉Taxus chinensis幼林地)和栽植年限分别为2,6(2009年冬天第1次覆盖),8,11,16和20 a(退化林地)的雷竹林地共8种/类样地(处理),每种(类)样地设3个采样样方,取样剖面分别为0～10,10～20和20～40 cm。结果表明:改植雷竹后,随着竹林栽培时间的延长,表层和亚表层土壤(0～10 cm和10～20 cm)酸碱度从对照的pH 6.53(水稻土)和pH 5.57(红豆杉幼林地)下降到pH 3.55(栽培20 a雷竹林地),土壤有机质和阳离子交换量在覆盖后逐渐上升,土壤腐殖质稳定性不断下降,而土壤电导率随竹林经营强度和施肥量的变化而呈前期上升后期下降的趋势。雷竹林表层和亚表层土壤(0～10 cm和10～20 cm)中8-羟基喹啉提取态铝质量分数随竹林栽培时间的延长和土壤酸度值的下降而增加,相比较于对照水稻田和红豆杉幼林地(10.08 mg.kg-1和22.94 mg.kg-1),栽培16 a后雷竹林土壤中8-羟基喹啉提取态铝质量分数高达108.01 mg.kg-1,分别高出对照(水稻土和红豆杉幼林地)10倍和5倍;雷竹林土壤中乙酸提取态铝与8-羟基喹啉提取态铝的变化趋势基本一致。相关分析表明:两者呈极显著正相关关系(r=0.911 7,P<0.000 1,校正后的R2=0.828 7)。以上结果说明:随着雷竹林集约经营时间的增加和土壤持续酸化,雷竹林地遭受铝毒胁迫的风险逐渐增加。

The influence of intensively cultivated Phyllostachys praecox on soil chemical properties such as soil acidity,the distribution of phytotoxic aluminum（Al） species that theoretically contribute to Al toxicity,and the contribution of Al toxicity to Ph.praecox bamboo forest damage and soil degradation were determined using a correlation analysis.We set eight stands：rice paddy field（Os） and juvenile Taxus chinensis foresty field（Tw） as controls,Ph.praecox stands that has been planted for 2,6,8,11,16 and 20 a in the town of Taihu headstream,Lin＇an,China.Results indicated that due to Ph.praecox cultivation,soil pH declined from 6.53（Os） and 5.57（Tw） to 3.55（Pp20） in the surface（0-10 cm） and subsurface（10-20 cm） layers,soil organic matters and cation exchange capacity（CEC） increased after organic matter mulching,and soil humus quality decreased;however,soil electrical conductivity rose in the earlier cultivation period and droped in the final phrase due to the intensity of cultivation and fertilization.The concentration of 8-hydroxyquinoline（HQN） extractable Al in the 0-10 and 10-20 cm soil layers also increased over time.The concentration of HQN extractable Al in forest soils of 16 a was 108.01 mg·kg-1,which compared to the controls,was 5 times higher than Os（22.94 mg·kg-1） and 10 times higher than Tw（10.08 mg·kg-1）.The concentration of acetic acid extractable Al had a consistent trend with the concentration of HQN extractable Al showing a highly significant positive correlation（r = 0.831 7,P 0.000 1,adjusted R2 = 0.687 4）.These results suggested that Al toxicity risk in soils of intensively cultivated P.praecox stands was increasing as a result of sustained acidification.