火烧对油松天然林林下植被及土壤的影响

Effect of Fire on Understory Vegetation and Soil in Pinus tabulaeformis Plantation

利用山西省国有林场火烧后油松天然林林下植被的样方调查资料,并通过室内分析,对2a后不同强度火干扰下的林下植被草本层和灌木层的植被物种组成及生物多样性和土壤的理化性质进行研究.结果表明（1）所有调查样地中林下植被的物种的组成及重要值和生物多样性随着火烧强度增加而上升,表现出重度火烧〉中轻度火烧〉未火烧的趋势,其中火烧后林下植被物种多样性的增加明显高于未受林火干扰的林下植被物种的多样性.（2）林火使土壤pH 升高,表现中轻度火烧〉重度火烧〉未火烧的趋势;与对照相比,中轻度火烧对油松林地土壤容重与全氮的变化趋势一样,土壤A层〈10cm 提高了5%、58.3%,10-20cm 却降低了9.2%、17.6%;重度火烧对林地土壤总孔隙度、全磷呈上升趋势,土壤A 层（10-20cm）与B层（10-20cm）分别上升了（8%、2%）、（20%、42%）,其中土壤全磷呈现显著差异水平.在自然更新的条件下,不同强度的火烧在一定程度上直接改变了油松天然林土壤养分的含量,也间接改变了林下植被的生物多样性.

Using state-owned forest farm of Shanxi Province after the fire of Pinus tabulaeformis forest undergrowth quadrat survey data,and through laboratory analysis,composition ,biodiversity and the soil physical and chemical properties vegetation species in herb and shrub layer understory vegetation under the fire interference with different strengths after 2 a were studied.Result shows that:1)Species composition in the undergrowth ,important value and biodiversity increase with the rise of fire intensity among all the survey sample area,which shows that serious fire> low-medium fire > unburned.The increase of species diversity understory vegetation are obviously higher than that without fire interference after the fire.2)The Ph value of the soil was increased by forest fires,and shows that low-medium fire > serious fire > unburned;compared to CK,the change trend of low-medium fire is the same with soil bulk density and total nitrogen of P .tabulaeformis .A layer of soil (< 10 cm)increase by 5% & 58.3%;A layer of soil (10-20 cm)decrease by 9.2% & 1 7.6%;the effect of serious burn on soil total porosity & total phosphorus of woodland appears the increasing trend;A layer of soil (10-20 cm)and B layer of soil (10-20 cm)in-crease by (8%,2%)& (20%,42%)respectively;total phosphorus of soil show levels with significant differ-ences.It shows that under the condition of natural regeneration,fire with different intensities not only change di-rectly soil nutrient content of P .tabulaeformis plantation,but also change indirectly the undergrowth biodiversity.